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coreboot-libre-fam15h-rdimm/3rdparty/chromeec/extra/i2c_pseudo/i2c-pseudo.c

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2024-03-04 11:14:53 +01:00
// SPDX-License-Identifier: GPL-2.0
/*
* This Linux kernel module implements pseudo I2C adapters that can be backed
* by userspace programs. This allows for implementing an I2C bus from
* userspace, which can tunnel the I2C commands through another communication
* channel to a remote I2C bus.
*/
#include <linux/build_bug.h>
#include <linux/cdev.h>
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/time64.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/wait.h>
#include "anprintf.h"
/* Minimum i2cp_limit module parameter value. */
#define I2CP_ADAPTERS_MIN 0
/* Maximum i2cp_limit module parameter value. */
#define I2CP_ADAPTERS_MAX 256
/* Default i2cp_limit module parameter value. */
#define I2CP_DEFAULT_LIMIT 8
/* Value for alloc_chrdev_region() baseminor arg. */
#define I2CP_CDEV_BASEMINOR 0
#define I2CP_TIMEOUT_MS_MIN 0
#define I2CP_TIMEOUT_MS_MAX (60 * MSEC_PER_SEC)
#define I2CP_DEFAULT_TIMEOUT_MS (3 * MSEC_PER_SEC)
/* Used in struct device.kobj.name field. */
#define I2CP_DEVICE_NAME "i2c-pseudo-controller"
/* Value for alloc_chrdev_region() name arg. */
#define I2CP_CHRDEV_NAME "i2c_pseudo"
/* Value for class_create() name arg. */
#define I2CP_CLASS_NAME "i2c-pseudo"
/* Value for alloc_chrdev_region() count arg. Should always be 1. */
#define I2CP_CDEV_COUNT 1
#define I2CP_ADAP_START_CMD "ADAPTER_START"
#define I2CP_ADAP_SHUTDOWN_CMD "ADAPTER_SHUTDOWN"
#define I2CP_GET_NUMBER_CMD "GET_ADAPTER_NUM"
#define I2CP_NUMBER_REPLY_CMD "I2C_ADAPTER_NUM"
#define I2CP_GET_PSEUDO_ID_CMD "GET_PSEUDO_ID"
#define I2CP_PSEUDO_ID_REPLY_CMD "I2C_PSEUDO_ID"
#define I2CP_SET_NAME_SUFFIX_CMD "SET_ADAPTER_NAME_SUFFIX"
#define I2CP_SET_TIMEOUT_CMD "SET_ADAPTER_TIMEOUT_MS"
#define I2CP_BEGIN_MXFER_REQ_CMD "I2C_BEGIN_XFER"
#define I2CP_COMMIT_MXFER_REQ_CMD "I2C_COMMIT_XFER"
#define I2CP_MXFER_REQ_CMD "I2C_XFER_REQ"
#define I2CP_MXFER_REPLY_CMD "I2C_XFER_REPLY"
/* Maximum size of a controller command. */
#define I2CP_CTRLR_CMD_LIMIT 255
/* Maximum number of controller read responses to allow enqueued at once. */
#define I2CP_CTRLR_RSP_QUEUE_LIMIT 256
/* The maximum size of a single controller read response. */
#define I2CP_MAX_MSG_BUF_SIZE 16384
/* Maximum length (not size!) of i2cp_cmds static array. */
#define I2CP_CMDS_SANITY_LIMIT 64
/* Maximum size of a controller read or write. */
#define I2CP_RW_SIZE_LIMIT 1048576
/*
* Marks the end of a controller command or read response.
*
* Fundamentally, controller commands and read responses could use different end
* marker characters, but for sanity they should be the same.
*
* This must be a variable, not a macro, because it is passed to copy_to_user()
* by address. Taking the address of a character literal causes a compiler
* error. Making these C strings instead of characters would allow for that
* (with other implications), but then copy_to_user() itself refuses to compile,
* because of an assertion that the copy size (1) must match the size of the
* string literal (2 with its trailing null).
*/
static const char i2cp_ctrlr_end_char = '\n';
/* Separator between I2C message header fields in the controller bytestream. */
static const char i2cp_ctrlr_header_sep_char = ' ';
/* Separator between I2C message data bytes in the controller bytestream. */
static const char i2cp_ctrlr_data_sep_char = ':';
/*
* This used instead of strcmp(in_str, other_str) because in_str may have null
* characters within its in_size boundaries, which could cause an unintended
* match.
*/
#define STRING_NEQ(in_str, in_size, other_str) \
(in_size != strlen(other_str) || memcmp(other_str, in_str, in_size))
#define STR_HELPER(x) #x
#define STR(x) STR_HELPER(x)
/*
* The number of pseudo I2C adapters permitted. This default value can be
* overridden at module load time. Must be in the range
* [I2CP_ADAPTERS_MIN, I2CP_ADAPTERS_MAX].
*
* As currently used, this MUST NOT be changed during or after module
* initialization. If the ability to change this at runtime is desired, an
* audit of the uses of this variable will be necessary.
*/
static unsigned int i2cp_limit = I2CP_DEFAULT_LIMIT;
module_param(i2cp_limit, uint, 0444);
/*
* The default I2C pseudo adapter timeout, in milliseconds.
* 0 means use Linux I2C adapter default.
* Can be changed per adapter by the controller.
*/
static unsigned int i2cp_default_timeout_ms = I2CP_DEFAULT_TIMEOUT_MS;
module_param(i2cp_default_timeout_ms, uint, 0444);
struct i2cp_controller;
/* This tracks all I2C pseudo adapters. */
struct i2cp_counters {
/* This must be held while accessing any fields. */
struct mutex lock;
unsigned int count;
/*
* This is used to make a strong attempt at avoiding ID reuse,
* especially during the lifetime of a userspace i2c-dev client. This
* can wrap by design, and thus makes no perfect guarantees.
*/
/* Same type as struct i2cp_controller.id field. */
unsigned int next_ctrlr_id;
struct i2cp_controller **all_controllers;
};
static struct class *i2cp_class;
static dev_t i2cp_dev_num;
struct i2cp_device {
struct i2cp_counters counters;
struct cdev cdev;
struct device device;
};
static struct i2cp_device *i2cp_device;
/*
* An instance of this struct in i2cp_cmds[] array defines a command that a
* controller process may write to the I2C pseudo character device, hereafter a
* "write command."
*
* A write command consists of one or more header fields, followed optionally by
* data. Each header field is fully buffered before being sent to
* header_receiver(). Data is not fully buffered, it is chunked in fixed
* increments set by the return value of the final header_receiver() call.
*
* Every write command begins with its name. The name is used both to map the
* command to an instance of this struct, and as the first header field.
*
* A header field ends at either i2cp_ctrlr_end_char or
* i2cp_ctrlr_header_sep_char, neither of which is ever included in header field
* values passed to a callback.
*
* A command always ends at i2cp_ctrlr_end_char. Anything written after that by
* the controller is treated as a new command.
*
* After i2cp_ctrlr_header_sep_char the return value of header_receiver() from
* the previous header field is used to determine whether subsequent input is
* another header field, or data.
*
* Once header_receiver() has indicated that data is expected, all input until
* i2cp_ctrlr_end_char will be handled as data, and header_receiver() will not
* be called again for the command.
*
* For a given I2C pseudo controller instance there will never be more than one
* write command in flight at once, and there will never be more than one of
* these callbacks executing at once. These callbacks need not do any
* cross-thread synchronization among themselves.
*
* Note: Data may contain i2cp_ctrlr_header_sep_char.
*
* Note: There are no restrictions on the use of the null char ('\0') in either
* header fields or data. (If either i2cp_ctrlr_header_sep_char or
* i2cp_ctrlr_end_char is null then the respective restrictions around those
* characters apply as usual, of course.) Write command implementations need
* not use or expect null, but they must at least handle it gracefully and fail
* without bad side effects, same as with any unexpected input.
*/
struct i2cp_cmd {
/*
* Set these to the command name.
*
* The command name must not contain i2cp_ctrlr_header_sep_char or
* i2cp_ctrlr_end_char. The behavior otherwise is undefined; such a
* command would be uncallable, and could become either a build-time or
* runtime error.
*
* The command name must be unique in the i2cp_cmds[] array. The
* behavior with duplicate command names is undefined, subject to
* change, and subject to become either a build-time or runtime error.
*/
char *cmd_string; /* Must be non-NULL. */
size_t cmd_size; /* Must be non-zero. */
/*
* This is called once for each I2C pseudo controller to initialize
* *data, prior to that pointer being passed to any other callbacks.
*
* This will only be called before the I2C adapter device is added.
*
* *data will be set to NULL before this is called.
*
* This callback may be NULL, in which case *data will remain NULL upon
* initialization.
*
* This should return -errno upon failure, 0 upon success. All
* non-negative return values are currently treated as success but
* positive values are reserved for potential future use.
*
* Initialization failure will cause the whole I2C pseudo controller to
* fail to initialize or function, thus *data will not be passed to any
* other callbacks.
*/
int (*data_creator)(void **data);
/*
* This is called once when shutdown of an I2C pseudo controller is
* imminent, and no further I2C replies can be processed.
*
* This callback may be NULL.
*/
void (*data_shutdown)(void *data);
/*
* This is called once upon termination of each I2C pseudo controller to
* free any resources held by @data.
*
* This will never be called while the I2C adapter device is active.
* Normally that means this is called after the I2C adapter device has
* been deleted, but it is also possible for this to be called during
* I2C pseudo controller initialization if a subsequent initialization
* step failed, as part of failure handling cleanup.
*
* This will only be called after a successful return value from
* data_creator().
*
* This will be passed the same *data pointer that data_creator() placed
* in its **data output arg.
*
* The *data pointer will not be used again by the write command system
* after the start of this function call.
*
* This callback may be NULL.
*/
void (*data_destroyer)(void *data);
/*
* This is called to process write command header fields, including the
* command name itself as the first header field in every command.
*
* This is called once for each header field, in order, including the
* initial command name.
*
* @data is the value of *data from data_creator(). (Thus NULL if
* data_creator field is NULL.)
*
* @in and @in_size are the header value. It will never contain
* i2cp_ctrlr_header_sep_char or i2cp_ctrlr_end_char.
*
* in[in_size] is guaranteed to be null. There may be null characters
* inside the buffer boundary indicated by @in_size as well though!
*
* @non_blocking indicates whether O_NONBLOCK is set on the controller
* file descriptor. This is not expected to be relevant to most write
* command callback implementations, however it should be respected if
* relevant. In other words, if this is true do not block indefinitely,
* instead return EAGAIN or EWOULDBLOCK. If this is false never return
* EAGAIN or EWOULDBLOCK.
*
* Return -errno to indicate a failure. After a failure the next and
* final callback invocation for the command will be cmd_completer().
*
* Return 0 to indicate success _and_ that another header field is
* expected next. The next header field will be fully buffered before
* being sent to this callback, just as the current one was.
*
* Return a positive value to indicate success _and_ that data is
* expected next. The exact positive value sets the chunk size used to
* buffer the data and pass it to data_receiver. All invocations of
* data_receiver are guaranteed to receive data in a _multiple_ of the
* chunk size, except the final invocation, because
* i2cp_ctrlr_end_char could be received on a non-chunk-size boundary.
* The return value should be less than I2CP_CTRLR_CMD_LIMIT, as that
* minus one is the maximum that will ever be buffered at once, and thus
* the maximum that will ever be sent to a single invocation of
* data_receiver.
*
* If the command is expected to end after a header field without any
* data, it is encouraged to return 1 here and have data_receiver
* indicate a failure if it is called. That avoids having the
* unexpected input buffered unnecessarily.
*
* This callback MUST NOT be NULL.
*/
int (*header_receiver)(void *data, char *in, size_t in_size,
bool non_blocking);
/*
* This is called to process write command data, when requested by the
* header_receiver() return value.
*
* This may be invoked multiple times for each data field, with the data
* broken up into sequential non-overlapping chunks.
*
* @in and @in_size are data. The data will never contain
* i2cp_ctrlr_end_char.
*
* in[in_size] is guaranteed to be null. There may be null characters
* inside the buffer boundary indicated by @in_size as well though!
*
* @in_size is guaranteed to be a multiple of the chunk size as
* specified by the last return value from header_receiver(), unless
* either the chunk size is >= I2CP_CTRLR_CMD_LIMIT, or
* i2cp_ctrlr_end_char was reached on a non-chunk-sized boundary.
*
* @in_size is guaranteed to be greater than zero, and less than
* I2CP_CTRLR_CMD_LIMIT.
*
* @non_blocking indicates whether O_NONBLOCK is set on the controller
* file descriptor. This is not expected to be relevant to most write
* command callback implementations, however it should be respected if
* relevant. In other words, if this is true do not block indefinitely,
* instead return EAGAIN or EWOULDBLOCK. If this is false never return
* EAGAIN or EWOULDBLOCK.
*
* This should return -errno upon failure, 0 upon success. All
* non-negative return values are currently treated as success but
* positive values are reserved for potential future use. After a
* failure the next and final callback invocation for the command will
* be cmd_completer().
*
* If header_receiver() never returns a positive number, this callback
* should be NULL. Otherwise, this callback MUST NOT be NULL.
*/
int (*data_receiver)(void *data, char *in, size_t in_size,
bool non_blocking);
/*
* This is called to complete processing of a command, after it has been
* received in its entirety.
*
* If @receive_status is positive, it is an error code from the invoking
* routines themselves, e.g. if the controller process wrote a header
* field >= I2CP_CTRLR_CMD_LIMIT.
*
* If @receive_status is zero, it means all invocations of
* header_receiver and data_receiver returned successful values and the
* entire write command was received successfully.
*
* If @receive_status is negative, it is the value returned by the last
* header_receiver or data_receiver invocation.
*
* @non_blocking indicates whether O_NONBLOCK is set on the controller
* file descriptor. This is not expected to be relevant to most write
* command callback implementations, however it should be respected if
* relevant. In other words, if this is true do not block indefinitely,
* instead return EAGAIN or EWOULDBLOCK. If this is false never return
* EAGAIN or EWOULDBLOCK.
*
* This is called exactly once for each write command. This is true
* regardless of the value of @non_blocking and regardless of the return
* value of this function, so it is imperative that this function
* perform any necessary cleanup tasks related to @data, even if
* non_blocking=true and blocking is required!
*
* Thus, even with non_blocking=true, it would only ever make sense to
* return -EAGAIN from this function if the struct i2cp_cmd
* implementation is able to perform the would-be blocked cmd_completer
* operation later, e.g. upon invocation of a callback for the next
* write command, or by way of a background thread.
*
* This should return -errno upon failure, 0 upon success. All
* non-negative return values are currently treated as success but
* positive values are reserved for potential future use.
*
* An error should be returned only to indicate a new error that
* happened during the execution of this callback. Any error from
* @receive_status should *not* be copied to the return value of this
* callback.
*
* This callback may be NULL.
*/
int (*cmd_completer)(void *data, struct i2cp_controller *pdata,
int receive_status, bool non_blocking);
};
/*
* These are indexes of i2cp_cmds[]. Every element in that array should have a
* corresponding value in this enum, and the enum value should be used in the
* i2cp_cmds[] initializer.
*
* Command names are matched in this order, so sort by expected frequency.
*/
enum {
I2CP_CMD_MXFER_REPLY_IDX = 0,
I2CP_CMD_ADAP_START_IDX,
I2CP_CMD_ADAP_SHUTDOWN_IDX,
I2CP_CMD_GET_NUMBER_IDX,
I2CP_CMD_GET_PSEUDO_ID_IDX,
I2CP_CMD_SET_NAME_SUFFIX_IDX,
I2CP_CMD_SET_TIMEOUT_IDX,
/* Keep this at the end! This must equal ARRAY_SIZE(i2cp_cmds). */
I2CP_NUM_WRITE_CMDS,
};
/*
* All values must be >= 0. This should not contain any error values.
*
* The state for a new controller must have a zero value, so that
* zero-initialized memory results in the correct default value.
*/
enum i2cp_ctrlr_state {
/*
* i2c_add_adapter() has not been called yet, or has only returned
* failure.
*/
I2CP_CTRLR_STATE_NEW = 0,
/*
* i2c_add_adapter() has return success, and the controller has not
* requested shutdown yet.
*/
I2CP_CTRLR_STATE_RUNNING,
/*
* i2c_add_adapter() has returned success, and the controller has
* requested shutdown.
*
* Note that it is perfectly acceptable for a pseudo controller fd to be
* closed and released without shutdown having been requested
* beforehand. Thus, this state is purely optional in the lifetime of a
* controller.
*/
I2CP_CTRLR_STATE_SHUTDN_REQ,
};
/*
* Avoid allocating this struct on the stack, it contains a large buffer as a
* direct member.
*
* To avoid deadlocks, never attempt to hold more than one of the locks in this
* structure at once, with the following exceptions:
* - It is permissible to acquire read_rsp_queue_lock while holding cmd_lock.
* - It is permissible to acquire read_rsp_queue_lock while holding rsp_lock.
*/
struct i2cp_controller {
unsigned int index;
/*
* Never modify the ID after initialization.
*
* This should be an unsigned integer type large enough to hold
* I2CP_ADAPTERS_MAX.
*/
unsigned int id;
/*
* Only i2cp_cdev_open() and i2cp_cdev_release() may access this field.
* Other functions called by them, or called by the I2C subsystem, may
* of course take a reference to this same struct i2c_adapter. However
* no other functions besides the aforementioned two may access the
* i2c_adapter field of struct i2cp_controller.
*/
struct i2c_adapter i2c_adapter;
struct mutex startstop_lock;
enum i2cp_ctrlr_state startstop_state;
wait_queue_head_t poll_wait_queue;
/* This must be held while read or writing cmd_* fields. */
struct mutex cmd_lock;
/*
* This becomes the @receive_status arg to struct i2cp_cmd.cmd_completer
* callback.
*
* A negative value is an error number from
* struct i2cp_cmd.header_receiver or struct i2cp_cmd.data_receiver.
*
* A zero value means no error has occurred so far in processing the
* current write reply command.
*
* A positive value is an error number from a non-command-specific part
* of write command processing, e.g. from the
* struct file_operations.write callback itself, or function further up
* its call stack that is not specific to any particular write command.
*/
int cmd_receive_status;
/*
* Index of i2cp_cmds[] and .cmd_data[] plus one, i.e. value of 1 means
* 0 index. Value of 0 (zero) means the controller is waiting for a new
* command.
*/
int cmd_idx_plus_one;
int cmd_data_increment;
size_t cmd_size;
/* Add one for trailing null character. */
char cmd_buf[I2CP_CTRLR_CMD_LIMIT + 1];
void *cmd_data[I2CP_NUM_WRITE_CMDS];
struct completion read_rsp_queued;
/* This must be held while read or writing read_rsp_queue_* fields. */
struct mutex read_rsp_queue_lock;
/*
* This is a FIFO queue of struct i2cp_rsp.queue .
*
* This MUST be strictly used as FIFO. Only consume or pop the first
* item. Only append to the end. Users of this queue assume this FIFO
* behavior is strictly followed, and their uses of read_rsp_queue_lock
* would not be safe otherwise.
*/
struct list_head read_rsp_queue_head;
unsigned int read_rsp_queue_length;
/* This must be held while reading or writing rsp_* fields. */
struct mutex rsp_lock;
bool rsp_invalidated;
/*
* Holds formatted string from most recently popped item of
* read_rsp_queue_head if it was not wholly consumed by the last
* controller read.
*/
char *rsp_buf_start;
char *rsp_buf_pos;
ssize_t rsp_buf_remaining;
};
struct i2cp_cmd_mxfer_reply {
/*
* This lock MUST be held while reading or modifying any part of this
* struct i2cp_cmd_mxfer_reply, unless you can guarantee that nothing
* else can access this struct concurrently, such as during
* initialization.
*
* The struct i2cp_cmd_mxfer_reply_data.reply_queue_lock of the
* struct i2cp_cmd_mxfer_reply_data.reply_queue_head list which contains
* this struct i2cp_cmd_mxfer_reply.reply_queue_item MUST be held when
* attempting to acquire this lock.
*
* It is NOT required to keep
* struct i2cp_cmd_mxfer_reply_data.reply_queue_lock held after
* acquisition of this lock (unless also manipulating
* struct i2cp_cmd_mxfer_reply_data.reply_queue_* of course).
*/
struct mutex lock;
/*
* Never modify the ID after initialization.
*
* This should be an unsigned integer type large enough to hold
* I2CP_CTRLR_RSP_QUEUE_LIMIT. If changing this type, audit for printf
* format strings that need updating!
*/
unsigned int id;
/* Number of I2C messages successfully processed, or negative error. */
int ret;
/* Same type as struct i2c_algorithm.master_xfer @num arg. */
int num_msgs;
/* Same type as struct i2c_algorithm.master_xfer @msgs arg. */
struct i2c_msg *msgs;
/* Same length (not size) as *msgs array. */
bool *completed;
/* Number of completed[] array entries with true value. */
int num_completed_true;
/*
* This is for use in struct i2cp_cmd_mxfer_reply_data.reply_queue_head
* FIFO queue.
*
* Any time this is deleted from its containing
* struct i2cp_cmd_mxfer_reply_data.reply_queue_head list, either
* list_del_init() MUST be used (not list_del()), OR this whole
* struct i2cp_cmd_mxfer_reply MUST be freed.
*
* That way, if this struct is not immediately freed, the code which
* eventually frees it can test whether it still needs to be deleted
* from struct i2cp_cmd_mxfer_reply_data.reply_queue_head by using
* list_empty() on reply_queue_item. (Calling list_del() on an
* already-deleted list item is unsafe.)
*/
struct list_head reply_queue_item;
struct completion data_filled;
};
/*
* The state for receiving the first field must have a zero value, so that
* zero-initialized memory results in the correct default value.
*/
enum i2cp_cmd_mxfer_reply_state {
I2CP_CMD_MXFER_REPLY_STATE_CMD_NEXT = 0,
I2CP_CMD_MXFER_REPLY_STATE_ID_NEXT,
I2CP_CMD_MXFER_REPLY_STATE_INDEX_NEXT,
I2CP_CMD_MXFER_REPLY_STATE_ADDR_NEXT,
I2CP_CMD_MXFER_REPLY_STATE_FLAGS_NEXT,
I2CP_CMD_MXFER_REPLY_STATE_ERRNO_NEXT,
I2CP_CMD_MXFER_REPLY_STATE_DATA_NEXT,
/*
* This is used to tell subsequent callback invocations that the write
* command currently being received is invalid, when the receiver wants
* to quietly discard the write command instead of loudly returning an
* error.
*/
I2CP_CMD_MXFER_REPLY_STATE_INVALID,
};
struct i2cp_cmd_mxfer_reply_data {
/* This must be held while read or writing reply_queue_* fields. */
struct mutex reply_queue_lock;
/*
* This is used to make a strong attempt at avoiding ID reuse,
* especially for overlapping master_xfer() calls.
*
* This can wrap by design, and thus makes no perfect guarantees over
* the lifetime of an I2C pseudo adapter.
*
* No code should assume uniqueness, not even for master_xfer() calls of
* overlapping lifetimes. When the controller writes a master_xfer()
* reply command, assume that it is for the oldest outstanding instance
* of the ID number specified.
*/
/* Same type as struct i2cp_cmd_mxfer_reply.id field. */
unsigned int next_mxfer_id;
/*
* This is a FIFO queue of struct i2cp_cmd_mxfer_reply.reply_queue_item.
*
* This MUST be strictly used as FIFO. Only consume or pop the first
* item. Only append to the end. Users of this queue assume this FIFO
* behavior is strictly followed, and their uses of reply_queue_lock may
* not be safe otherwise.
*/
struct list_head reply_queue_head;
unsigned int reply_queue_length;
struct i2cp_cmd_mxfer_reply *reply_queue_current_item;
enum i2cp_cmd_mxfer_reply_state state;
/* Same type as struct i2cp_cmd_mxfer_reply.id field. */
unsigned int current_id;
/* Same type as struct i2c_msg.addr field. */
u16 current_addr;
/* Same type as struct i2c_msg.flags field. */
u16 current_flags;
/* Same type as struct i2c_algorithm.master_xfer @num arg. */
int current_msg_idx;
/* Same type as struct i2c_msg.len field. */
u16 current_buf_idx;
};
struct i2cp_cmd_set_name_suffix_data {
char name_suffix[FIELD_SIZEOF(struct i2c_adapter, name)];
size_t name_suffix_len;
};
struct i2cp_cmd_set_timeout_data {
int field_pos;
unsigned int timeout_ms;
};
struct i2cp_rsp {
/*
* This callback is invoked to format its associated data for passing to
* the userspace controller process when it read()s the I2C pseudo
* controller character device.
*
* @data will be the data pointer from this struct instance.
*
* @out is an output argument. Upon positive return value, *out must be
* set to a buffer which the caller will take ownership of, and which
* can be freed with kfree().
*
* Upon positive return value, @data must NOT be freed.
*
* The formatter will be called repeatedly for the same data until it
* returns non-positive.
*
* Upon non-positive return value, *out should not be modified.
*
* Upon non-positive return value, the formatter should have freed data
* with kfree(). Implicitly this means any allocations owned by *data
* should have been freed by the formatter as well.
*
* A negative return value indicates an error occurred and the data
* cannot be formatted successfully. The error code may or may not
* eventually be propagated back to the I2C pseudo adapter controller.
*
* A positive return value is the number of characters/bytes to use from
* the *out buffer, always starting from index 0. It should NOT include
* a trailing NULL character unless that character should be propagated
* to the I2C pseudo adapter controller! It therefore does NOT need to
* be the full size of the allocated *out buffer, instead it can be
* less. (The size is not needed by kfree().)
*
* The formatter owns the memory pointed to by data. The invoking code
* will never mutate or free data. Thus, upon non-positive return value
* from the formatter, the formatter must have already performed any
* reference counting decrement or memory freeing necessary to ensure
* data does not live beyond its final use.
*
* There will never be more than one formatter callback in flight at
* once for a given I2C pseudo controller. This is true even in the
* face of concurrent reads by the controller.
*
* The formatter must NOT use i2cp_ctrlr_end_char in anywhere in *out
* (within the size range indicated by the return value; past that does
* not matter). The i2cp_ctrlr_end_char will be added automatically by
* the caller after a zero return value (successful completion) from the
* formatter.
*
* The formatter must never create or return a buffer larger than
* I2CP_MAX_MSG_BUF_SIZE. The formatter is encouraged to avoid that by
* generating and returning the output in chunks, taking advantage of
* the guarantee that it will be called repeatedly until exhaustion
* (zero return value) or failure (negative return value). If the
* formatter expects its formatted output or natural subsets of it to
* always fit within I2CP_MAX_MSG_BUF_SIZE, and it is called with input
* data not meeting that expectation, the formatter should return
* -ERANGE to indicate this condition.
*/
ssize_t (*formatter)(void *data, char **out);
void *data;
struct list_head queue;
};
struct i2cp_rsp_buffer {
char *buf;
ssize_t size;
};
struct i2cp_rsp_master_xfer {
/* Never modify the ID after initialization. */
/* Same type as struct i2cp_cmd_mxfer_reply.id field. */
unsigned int id;
/* These types match those of struct i2c_algorithm.master_xfer args. */
struct i2c_msg *msgs;
int num;
/*
* Always initialize fields below here to zero. They are for internal
* use by i2cp_rsp_master_xfer_formatter().
*/
int num_msgs_done; /* type of @num field */
size_t buf_start_plus_one;
};
static ssize_t i2cp_rsp_buffer_formatter(void *data, char **out)
{
struct i2cp_rsp_buffer *rsp_buf;
rsp_buf = data;
if (rsp_buf->buf) {
if (rsp_buf->size > 0) {
*out = rsp_buf->buf;
rsp_buf->buf = NULL;
return rsp_buf->size;
}
kfree(rsp_buf->buf);
}
kfree(rsp_buf);
return 0;
}
static ssize_t i2cp_rsp_master_xfer_formatter(void *data, char **out)
{
ssize_t ret;
size_t i, buf_size, byte_start, byte_limit;
char *buf_start, *buf_pos;
struct i2cp_rsp_master_xfer *mxfer_rsp;
struct i2c_msg *i2c_msg;
mxfer_rsp = data;
/*
* This condition is set by a previous call to this function with the
* same data, when it returned an error but was not consuming the final
* i2c_msg.
*/
if (!mxfer_rsp->msgs) {
++mxfer_rsp->num_msgs_done;
ret = 0;
goto maybe_free;
}
i2c_msg = &mxfer_rsp->msgs[mxfer_rsp->num_msgs_done];
/*
* If this is a read, or if this is a write and we've finished writing
* the data buffer, we are done with this i2c_msg.
*/
if (mxfer_rsp->buf_start_plus_one >= 1 &&
(i2c_msg->flags & I2C_M_RD ||
mxfer_rsp->buf_start_plus_one >= (size_t)i2c_msg->len + 1)) {
++mxfer_rsp->num_msgs_done;
mxfer_rsp->buf_start_plus_one = 0;
ret = 0;
goto maybe_free;
}
if (mxfer_rsp->buf_start_plus_one <= 0) {
/*
* The length is not strictly necessary with the explicit
* end-of-message marker (i2cp_ctrlr_end_char), however it
* serves as a useful sanity check for controllers to verify
* that no bytes were lost in kernel->userspace transmission.
*/
ret = anprintf(&buf_start, I2CP_MAX_MSG_BUF_SIZE, GFP_KERNEL,
"%*s%c%u%c%d%c0x%04X%c0x%04X%c%u",
(int)strlen(I2CP_MXFER_REQ_CMD), I2CP_MXFER_REQ_CMD,
i2cp_ctrlr_header_sep_char, mxfer_rsp->id,
i2cp_ctrlr_header_sep_char, mxfer_rsp->num_msgs_done,
i2cp_ctrlr_header_sep_char, i2c_msg->addr,
i2cp_ctrlr_header_sep_char, i2c_msg->flags,
i2cp_ctrlr_header_sep_char, i2c_msg->len);
if (ret > 0) {
*out = buf_start;
mxfer_rsp->buf_start_plus_one = 1;
/*
* If we have a zero return value, it means the output buffer
* was allocated as size one, containing only a terminating null
* character. This would be a bug given the requested format
* string above. Also, formatter functions must not mutate *out
* when returning zero. So if this matches, free the useless
* buffer and return an error.
*/
} else if (ret == 0) {
ret = -EINVAL;
kfree(buf_start);
}
goto maybe_free;
}
byte_start = mxfer_rsp->buf_start_plus_one - 1;
byte_limit = min_t(size_t, i2c_msg->len - byte_start,
I2CP_MAX_MSG_BUF_SIZE / 3);
/* 3 chars per byte == 2 chars for hex + 1 char for separator */
buf_size = byte_limit * 3;
buf_start = kzalloc(buf_size, GFP_KERNEL);
if (!buf_start) {
ret = -ENOMEM;
goto maybe_free;
}
for (buf_pos = buf_start, i = 0; i < byte_limit; ++i) {
*buf_pos++ = (i || byte_start) ?
i2cp_ctrlr_data_sep_char : i2cp_ctrlr_header_sep_char;
buf_pos = hex_byte_pack_upper(
buf_pos, i2c_msg->buf[byte_start + i]);
}
*out = buf_start;
ret = buf_size;
mxfer_rsp->buf_start_plus_one += i;
maybe_free:
if (ret <= 0) {
if (mxfer_rsp->num_msgs_done >= mxfer_rsp->num) {
kfree(mxfer_rsp->msgs);
kfree(mxfer_rsp);
/*
* If we are returning an error but have not consumed all of
* mxfer_rsp yet, we must not attempt to output any more I2C
* messages from the same mxfer_rsp. Setting mxfer_rsp->msgs to
* NULL tells the remaining invocations with this mxfer_rsp to
* output nothing.
*
* There can be more invocations with the same mxfer_rsp even
* after returning an error here because
* i2cp_adapter_master_xfer() reuses a single
* struct i2cp_rsp_master_xfer (mxfer_rsp) across multiple
* struct i2cp_rsp (rsp_wrappers), one for each struct i2c_msg
* within the mxfer_rsp.
*/
} else if (ret < 0) {
kfree(mxfer_rsp->msgs);
mxfer_rsp->msgs = NULL;
}
}
return ret;
}
static ssize_t i2cp_id_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
int ret;
struct i2c_adapter *adap;
struct i2cp_controller *pdata;
adap = container_of(dev, struct i2c_adapter, dev);
pdata = container_of(adap, struct i2cp_controller, i2c_adapter);
ret = snprintf(buf, PAGE_SIZE, "%u\n", pdata->id);
if (ret >= PAGE_SIZE)
return -ERANGE;
return ret;
}
static const struct device_attribute i2cp_id_dev_attr = {
.attr = {
.name = "i2c-pseudo-id",
.mode = 0444,
},
.show = i2cp_id_show,
};
static enum i2cp_ctrlr_state i2cp_adap_get_state(struct i2cp_controller *pdata)
{
enum i2cp_ctrlr_state ret;
mutex_lock(&pdata->startstop_lock);
ret = pdata->startstop_state;
mutex_unlock(&pdata->startstop_lock);
return ret;
}
static int i2cp_cmd_mxfer_reply_data_creator(void **data)
{
struct i2cp_cmd_mxfer_reply_data *cmd_data;
cmd_data = kzalloc(sizeof(*cmd_data), GFP_KERNEL);
if (!cmd_data)
return -ENOMEM;
mutex_init(&cmd_data->reply_queue_lock);
INIT_LIST_HEAD(&cmd_data->reply_queue_head);
*data = cmd_data;
return 0;
}
/*
* Notify pending I2C requests of the shutdown. There is no possibility of
* further I2C replies at this point. This stops the I2C requests from waiting
* for the adapter timeout, which could have been set arbitrarily long by the
* userspace controller.
*/
static void i2cp_cmd_mxfer_reply_data_shutdown(void *data)
{
struct list_head *list_ptr;
struct i2cp_cmd_mxfer_reply_data *cmd_data;
struct i2cp_cmd_mxfer_reply *mxfer_reply;
cmd_data = data;
mutex_lock(&cmd_data->reply_queue_lock);
list_for_each(list_ptr, &cmd_data->reply_queue_head) {
mxfer_reply = list_entry(list_ptr, struct i2cp_cmd_mxfer_reply,
reply_queue_item);
mutex_lock(&mxfer_reply->lock);
complete_all(&mxfer_reply->data_filled);
mutex_unlock(&mxfer_reply->lock);
}
mutex_unlock(&cmd_data->reply_queue_lock);
}
static void i2cp_cmd_mxfer_reply_data_destroyer(void *data)
{
/*
* We do not have to worry about racing with in-flight I2C messages
* because data_destroyer callbacks are guaranteed to never be called
* while the I2C adapter device is active.
*/
kfree(data);
}
static inline bool i2cp_mxfer_reply_is_current(
struct i2cp_cmd_mxfer_reply_data *cmd_data,
struct i2cp_cmd_mxfer_reply *mxfer_reply)
{
int i;
i = cmd_data->current_msg_idx;
return cmd_data->current_id == mxfer_reply->id &&
i >= 0 && i < mxfer_reply->num_msgs &&
cmd_data->current_addr == mxfer_reply->msgs[i].addr &&
cmd_data->current_flags == mxfer_reply->msgs[i].flags;
}
/* cmd_data->reply_queue_lock must be held. */
static inline struct i2cp_cmd_mxfer_reply *i2cp_mxfer_reply_find_current(
struct i2cp_cmd_mxfer_reply_data *cmd_data)
{
struct list_head *list_ptr;
struct i2cp_cmd_mxfer_reply *mxfer_reply;
list_for_each(list_ptr, &cmd_data->reply_queue_head) {
mxfer_reply = list_entry(list_ptr, struct i2cp_cmd_mxfer_reply,
reply_queue_item);
if (i2cp_mxfer_reply_is_current(cmd_data, mxfer_reply))
return mxfer_reply;
}
return NULL;
}
/* cmd_data->reply_queue_lock must NOT already be held. */
static inline void i2cp_mxfer_reply_update_current(
struct i2cp_cmd_mxfer_reply_data *cmd_data)
{
mutex_lock(&cmd_data->reply_queue_lock);
cmd_data->reply_queue_current_item = i2cp_mxfer_reply_find_current(
cmd_data);
mutex_unlock(&cmd_data->reply_queue_lock);
}
static int i2cp_cmd_mxfer_reply_header_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
int ret, reply_errno = 0;
struct i2cp_cmd_mxfer_reply_data *cmd_data;
cmd_data = data;
switch (cmd_data->state) {
case I2CP_CMD_MXFER_REPLY_STATE_CMD_NEXT:
/* Expect the msg/reply ID header field next. */
cmd_data->state = I2CP_CMD_MXFER_REPLY_STATE_ID_NEXT;
return 0;
case I2CP_CMD_MXFER_REPLY_STATE_ID_NEXT:
case I2CP_CMD_MXFER_REPLY_STATE_INDEX_NEXT:
case I2CP_CMD_MXFER_REPLY_STATE_ADDR_NEXT:
case I2CP_CMD_MXFER_REPLY_STATE_FLAGS_NEXT:
case I2CP_CMD_MXFER_REPLY_STATE_ERRNO_NEXT:
break;
default:
/* Reaching here is a bug. */
/*
* Testing this before checking for null characters ensures the
* correct error is indicated.
*/
return -EINVAL;
}
/*
* The command name is logically outside the control of this function,
* and may contain null characters, even if that would be nonsensical.
* Thus it is handled above, followed by this check, and below here
* the rest of the header fields are handled. Some of them use
* functions that could mishandle input which contains nulls. An actual
* error would be okay, however if the input were consumed incorrectly
* without an error, that could lead to subtle bugs.
*/
if (memchr(in, '\0', in_size))
return -EPROTO;
switch (cmd_data->state) {
case I2CP_CMD_MXFER_REPLY_STATE_ID_NEXT:
ret = kstrtouint(in, 0, &cmd_data->current_id);
if (ret < 0)
return ret;
cmd_data->state = I2CP_CMD_MXFER_REPLY_STATE_INDEX_NEXT;
return 0;
case I2CP_CMD_MXFER_REPLY_STATE_INDEX_NEXT:
ret = kstrtoint(in, 0, &cmd_data->current_msg_idx);
if (ret < 0)
return ret;
cmd_data->state = I2CP_CMD_MXFER_REPLY_STATE_ADDR_NEXT;
return 0;
case I2CP_CMD_MXFER_REPLY_STATE_ADDR_NEXT:
ret = kstrtou16(in, 0, &cmd_data->current_addr);
if (ret < 0)
return ret;
cmd_data->state = I2CP_CMD_MXFER_REPLY_STATE_FLAGS_NEXT;
return 0;
case I2CP_CMD_MXFER_REPLY_STATE_FLAGS_NEXT:
ret = kstrtou16(in, 0, &cmd_data->current_flags);
if (ret < 0)
return ret;
cmd_data->state = I2CP_CMD_MXFER_REPLY_STATE_ERRNO_NEXT;
return 0;
case I2CP_CMD_MXFER_REPLY_STATE_ERRNO_NEXT:
ret = kstrtoint(in, 0, &reply_errno);
if (ret < 0)
return ret;
break;
default:
/* Reaching here is a bug. */
return -EINVAL;
}
/*
* Only I2CP_CMD_MXFER_REPLY_STATE_ERRNO_NEXT can reach this point.
* Now that we've received all of the headers, find the matching
* mxfer_reply.
*/
i2cp_mxfer_reply_update_current(cmd_data);
if (reply_errno || !cmd_data->reply_queue_current_item) {
/*
* reply_errno:
* Drop the specific errno for now. The Linux I2C API
* does not provide a way to return an errno for a
* specific message within a master_xfer() call. The
* cmd_completer callback will indicate this
* controller-reported failure by not incrementing
* mxfer_reply->ret for this I2C msg reply.
*
* cmd_data->reply_queue_current_item == NULL:
* No matching mxfer_reply was found. Discard any
* further input in this command. The cmd_completer
* callback will indicate this failure to the
* controller.
*/
cmd_data->state = I2CP_CMD_MXFER_REPLY_STATE_INVALID;
/*
* Ask for data bytes in multiples of 1, i.e. no
* boundary requirements, because the we're just going
* to discard it. The next field could even be a header
* instead of data, but it doesn't matter, we're going
* to continue discarding the write input until the end
* of this write command.
*/
return 1;
}
cmd_data->state = I2CP_CMD_MXFER_REPLY_STATE_DATA_NEXT;
/*
* Ask for data bytes in multiples of 3. Expected format is
* hexadecimal NN:NN:... e.g. "3C:05:F1:01" is a possible 4 byte
* data value.
*/
return 3;
}
static int i2cp_cmd_mxfer_reply_data_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
int ret;
char u8_hex[3] = {0};
struct i2cp_cmd_mxfer_reply_data *cmd_data;
struct i2cp_cmd_mxfer_reply *mxfer_reply;
struct i2c_msg *i2c_msg;
cmd_data = data;
if (cmd_data->state == I2CP_CMD_MXFER_REPLY_STATE_INVALID)
return 0;
if (cmd_data->state != I2CP_CMD_MXFER_REPLY_STATE_DATA_NEXT)
/* Reaching here is a bug. */
return -EINVAL;
mutex_lock(&cmd_data->reply_queue_lock);
mxfer_reply = cmd_data->reply_queue_current_item;
if (!mxfer_reply) {
/* Reaching here is a bug. */
mutex_unlock(&cmd_data->reply_queue_lock);
return -EINVAL;
}
mutex_lock(&mxfer_reply->lock);
mutex_unlock(&cmd_data->reply_queue_lock);
if (cmd_data->current_msg_idx < 0 ||
cmd_data->current_msg_idx >= mxfer_reply->num_msgs) {
/* Reaching here is a bug. */
ret = -EINVAL;
goto unlock;
}
i2c_msg = &mxfer_reply->msgs[cmd_data->current_msg_idx];
if (!(i2c_msg->flags & I2C_M_RD)) {
/* The controller responded to a write with data. */
ret = -EIO;
goto unlock;
}
if (i2c_msg->flags & I2C_M_RECV_LEN) {
/*
* When I2C_M_RECV_LEN is set, struct i2c_algorithm.master_xfer
* is expected to increment struct i2c_msg.len by the actual
* amount of bytes read.
*
* Given the above, an initial struct i2c_msg.len value of 0
* would be reasonable, since it will be incremented for each
* byte read.
*
* An initial value of 1 representing the expected size byte
* also makes sense, and appears to be common practice.
*
* We consider a larger initial value to indicate a bug in the
* I2C/SMBus client, because it's difficult to reconcile such a
* value with the documented requirement that struct i2c_msg.len
* be "incremented by the number of block data bytes received."
* Besides returning an error, our only options would be to
* ignore and blow away a value that was potentially meaningful
* to the client (e.g. if it indicates the maximum buffer size),
* assume the value is the buffer size or expected read size
* (which would conflict with the documentation), or just
* blindly increment it, leaving it at a value greater than the
* actual number of bytes we wrote to the buffer, and likely
* indicating a size larger than the actual buffer allocation.
*/
if (cmd_data->current_buf_idx == 0) {
if (i2c_msg->len > 1) {
ret = -EPROTO;
goto unlock;
}
/*
* Subtract the read size byte because the in_size
* increment in the loop below will re-add it.
*/
i2c_msg->len = 0;
}
}
while (in_size > 0 && cmd_data->current_buf_idx < i2c_msg->len) {
if (in_size < 2 ||
(in_size > 2 && in[2] != i2cp_ctrlr_data_sep_char) ||
memchr(in, '\0', 2)) {
/*
* Reaching here is a bug in the userspace I2C pseudo
* adapter controller. (Or possibly a bug in this
* module itself, of course.)
*/
ret = -EIO;
goto unlock;
}
/*
* When using I2C_M_RECV_LEN, the buffer is required to be able
* to hold:
*
* I2C_SMBUS_BLOCK_MAX
* +1 byte for the read size (first byte)
* +1 byte for the optional PEC byte (last byte if present).
*
* If reading the next byte would exceed that, return EPROTO
* error per Documentation/i2c/fault-codes .
*/
if (i2c_msg->flags & I2C_M_RECV_LEN &&
i2c_msg->len >= I2C_SMBUS_BLOCK_MAX + 2) {
ret = -EPROTO;
goto unlock;
}
/* Use u8_hex to get a terminating null byte for kstrtou8(). */
memcpy(u8_hex, in, 2);
/*
* TODO: Do we need to do anything different based on the
* I2C_M_DMA_SAFE bit? Do we ever need to use copy_to_user()?
*/
ret = kstrtou8(u8_hex, 16,
&i2c_msg->buf[cmd_data->current_buf_idx]);
if (ret < 0)
goto unlock;
if (i2c_msg->flags & I2C_M_RECV_LEN)
++i2c_msg->len;
++cmd_data->current_buf_idx;
in += min_t(size_t, 3, in_size);
in_size -= min_t(size_t, 3, in_size);
}
/* Quietly ignore any bytes beyond the buffer size. */
ret = 0;
unlock:
mutex_unlock(&mxfer_reply->lock);
return ret;
}
static int i2cp_cmd_mxfer_reply_cmd_completer(void *data,
struct i2cp_controller *pdata, int receive_status, bool non_blocking)
{
int ret;
struct i2cp_cmd_mxfer_reply_data *cmd_data;
struct i2cp_cmd_mxfer_reply *mxfer_reply;
struct i2c_msg *i2c_msg;
cmd_data = data;
mutex_lock(&cmd_data->reply_queue_lock);
mxfer_reply = cmd_data->reply_queue_current_item;
if (!mxfer_reply) {
mutex_unlock(&cmd_data->reply_queue_lock);
ret = -EIO;
goto reset_cmd_data;
}
mutex_lock(&mxfer_reply->lock);
if (mxfer_reply->completed[cmd_data->current_msg_idx]) {
/* We already received a reply for this msg. */
mutex_unlock(&cmd_data->reply_queue_lock);
mutex_unlock(&mxfer_reply->lock);
ret = -EIO;
goto reset_cmd_data;
}
mxfer_reply->completed[cmd_data->current_msg_idx] = true;
if (++mxfer_reply->num_completed_true >= mxfer_reply->num_msgs) {
list_del_init(&mxfer_reply->reply_queue_item);
--cmd_data->reply_queue_length;
cmd_data->reply_queue_current_item = NULL;
complete_all(&mxfer_reply->data_filled);
}
mutex_unlock(&cmd_data->reply_queue_lock);
i2c_msg = &mxfer_reply->msgs[cmd_data->current_msg_idx];
if (!receive_status &&
cmd_data->state == I2CP_CMD_MXFER_REPLY_STATE_DATA_NEXT &&
(!(i2c_msg->flags & I2C_M_RD) ||
cmd_data->current_buf_idx >= i2c_msg->len))
++mxfer_reply->ret;
mutex_unlock(&mxfer_reply->lock);
ret = 0;
reset_cmd_data:
cmd_data->state = I2CP_CMD_MXFER_REPLY_STATE_CMD_NEXT;
cmd_data->current_id = 0;
cmd_data->current_addr = 0;
cmd_data->current_flags = 0;
cmd_data->current_msg_idx = 0;
cmd_data->current_buf_idx = 0;
return ret;
}
static int i2cp_cmd_adap_start_header_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
/*
* No more header fields or data are expected. This directs any further
* input in this command to the data_receiver, which for this write
* command will unconditionally indicate a controller error.
*/
return 1;
}
static int i2cp_cmd_adap_start_data_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
/*
* Reaching here means the controller wrote extra data in the command
* line after the initial command name. That is unexpected and
* indicates a controller bug.
*/
return -EPROTO;
}
static int i2cp_cmd_adap_start_cmd_completer(void *data,
struct i2cp_controller *pdata, int receive_status, bool non_blocking)
{
int ret;
/* Refuse to start if there were errors processing this command. */
if (receive_status)
return 0;
/*
* Acquire pdata->startstop_lock manually instead of using
* i2cp_adap_get_state() in order to keep the lock while calling
* i2c_add_adapter().
*/
mutex_lock(&pdata->startstop_lock);
if (pdata->startstop_state != I2CP_CTRLR_STATE_NEW) {
ret = -EISCONN;
goto unlock;
}
/* Add the I2C adapter. */
ret = i2c_add_adapter(&pdata->i2c_adapter);
if (ret < 0)
goto unlock;
pdata->startstop_state = I2CP_CTRLR_STATE_RUNNING;
/* Add the I2C pseudo controller ID sysfs file. */
ret = device_create_file(&pdata->i2c_adapter.dev, &i2cp_id_dev_attr);
if (ret < 0)
goto unlock;
ret = 0;
unlock:
mutex_unlock(&pdata->startstop_lock);
return ret;
}
static int i2cp_cmd_adap_shutdown_header_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
/*
* No more header fields or data are expected. This directs any further
* input in this command to the data_receiver, which for this write
* command will unconditionally indicate a controller error.
*/
return 1;
}
static int i2cp_cmd_adap_shutdown_data_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
/*
* Reaching here means the controller wrote extra data in the command
* line after the initial command name. That is unexpected and
* indicates a controller bug.
*/
return -EPROTO;
}
static int i2cp_cmd_adap_shutdown_cmd_completer(void *data,
struct i2cp_controller *pdata, int receive_status, bool non_blocking)
{
/* Refuse to shutdown if there were errors processing this command. */
if (receive_status)
return 0;
mutex_lock(&pdata->startstop_lock);
pdata->startstop_state = I2CP_CTRLR_STATE_SHUTDN_REQ;
mutex_unlock(&pdata->startstop_lock);
/* Wake up blocked controller readers. */
complete_all(&pdata->read_rsp_queued);
/* Wake up blocked controller pollers. */
wake_up_interruptible_all(&pdata->poll_wait_queue);
return 0;
}
static int i2cp_cmd_get_number_header_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
/*
* No more header fields or data are expected. This directs any further
* input in this command to the data_receiver, which for this write
* command will unconditionally indicate a controller error.
*/
return 1;
}
static int i2cp_cmd_get_number_data_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
/*
* Reaching here means the controller wrote extra data in the command
* line after the initial command name. That is unexpected and
* indicates a controller bug.
*/
return -EPROTO;
}
static int i2cp_cmd_get_number_cmd_completer(void *data,
struct i2cp_controller *pdata, int receive_status, bool non_blocking)
{
ssize_t ret;
int i2c_adap_nr;
struct i2cp_rsp_buffer *rsp_buf;
struct i2cp_rsp *rsp_wrapper;
/* Abort if there were errors processing this command. */
if (receive_status)
return 0;
/*
* Check the pseudo controller startstop_state. If it's running, get
* the I2C adapter number.
*
* Acquire pdata->startstop_lock manually instead of using
* i2cp_adap_get_state() in order to keep the lock while retrieving the
* I2C adapter number.
*/
mutex_lock(&pdata->startstop_lock);
if (pdata->startstop_state != I2CP_CTRLR_STATE_RUNNING) {
mutex_unlock(&pdata->startstop_lock);
return -ENOTCONN;
}
i2c_adap_nr = pdata->i2c_adapter.nr;
mutex_unlock(&pdata->startstop_lock);
rsp_wrapper = kzalloc(sizeof(*rsp_wrapper), GFP_KERNEL);
if (!rsp_wrapper)
return -ENOMEM;
rsp_buf = kzalloc(sizeof(*rsp_buf), GFP_KERNEL);
if (!rsp_buf) {
ret = -ENOMEM;
goto fail_after_rsp_wrapper_alloc;
}
ret = anprintf(&rsp_buf->buf, I2CP_MAX_MSG_BUF_SIZE, GFP_KERNEL,
"%*s%c%d",
(int)strlen(I2CP_NUMBER_REPLY_CMD), I2CP_NUMBER_REPLY_CMD,
i2cp_ctrlr_header_sep_char, i2c_adap_nr);
if (ret < 0) {
goto fail_after_rsp_buf_alloc;
} else if (ret == 0) {
ret = -EINVAL;
goto fail_after_buf_alloc;
}
rsp_buf->size = ret;
rsp_wrapper->data = rsp_buf;
rsp_wrapper->formatter = i2cp_rsp_buffer_formatter;
mutex_lock(&pdata->read_rsp_queue_lock);
if (pdata->read_rsp_queue_length >= I2CP_CTRLR_RSP_QUEUE_LIMIT) {
ret = -ENOBUFS;
mutex_unlock(&pdata->read_rsp_queue_lock);
goto fail_after_buf_alloc;
}
list_add_tail(&rsp_wrapper->queue, &pdata->read_rsp_queue_head);
++pdata->read_rsp_queue_length;
complete(&pdata->read_rsp_queued);
mutex_unlock(&pdata->read_rsp_queue_lock);
return 0;
fail_after_buf_alloc:
kfree(rsp_buf->buf);
fail_after_rsp_buf_alloc:
kfree(rsp_buf);
fail_after_rsp_wrapper_alloc:
kfree(rsp_wrapper);
return ret;
}
static int i2cp_cmd_get_pseudo_id_header_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
/*
* No more header fields or data are expected. This directs any further
* input in this command to the data_receiver, which for this write
* command will unconditionally indicate a controller error.
*/
return 1;
}
static int i2cp_cmd_get_pseudo_id_data_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
/*
* Reaching here means the controller wrote extra data in the command
* line after the initial command name. That is unexpected and
* indicates a controller bug.
*/
return -EPROTO;
}
static int i2cp_cmd_get_pseudo_id_cmd_completer(void *data,
struct i2cp_controller *pdata, int receive_status, bool non_blocking)
{
ssize_t ret;
struct i2cp_rsp_buffer *rsp_buf;
struct i2cp_rsp *rsp_wrapper;
/* Abort if there were errors processing this command. */
if (receive_status)
return 0;
rsp_wrapper = kzalloc(sizeof(*rsp_wrapper), GFP_KERNEL);
if (!rsp_wrapper)
return -ENOMEM;
rsp_buf = kzalloc(sizeof(*rsp_buf), GFP_KERNEL);
if (!rsp_buf) {
ret = -ENOMEM;
goto fail_after_rsp_wrapper_alloc;
}
ret = anprintf(&rsp_buf->buf, I2CP_MAX_MSG_BUF_SIZE, GFP_KERNEL,
"%*s%c%u",
(int)strlen(I2CP_PSEUDO_ID_REPLY_CMD), I2CP_PSEUDO_ID_REPLY_CMD,
i2cp_ctrlr_header_sep_char, pdata->id);
if (ret < 0) {
goto fail_after_rsp_buf_alloc;
} else if (ret == 0) {
ret = -EINVAL;
goto fail_after_buf_alloc;
}
rsp_buf->size = ret;
rsp_wrapper->data = rsp_buf;
rsp_wrapper->formatter = i2cp_rsp_buffer_formatter;
mutex_lock(&pdata->read_rsp_queue_lock);
if (pdata->read_rsp_queue_length >= I2CP_CTRLR_RSP_QUEUE_LIMIT) {
ret = -ENOBUFS;
mutex_unlock(&pdata->read_rsp_queue_lock);
goto fail_after_buf_alloc;
}
list_add_tail(&rsp_wrapper->queue, &pdata->read_rsp_queue_head);
++pdata->read_rsp_queue_length;
complete(&pdata->read_rsp_queued);
mutex_unlock(&pdata->read_rsp_queue_lock);
return 0;
fail_after_buf_alloc:
kfree(rsp_buf->buf);
fail_after_rsp_buf_alloc:
kfree(rsp_buf);
fail_after_rsp_wrapper_alloc:
kfree(rsp_wrapper);
return ret;
}
static int i2cp_cmd_set_name_suffix_data_creator(void **data)
{
struct i2cp_cmd_set_name_suffix_data *cmd_data;
cmd_data = kzalloc(sizeof(*cmd_data), GFP_KERNEL);
if (!cmd_data)
return -ENOMEM;
*data = cmd_data;
return 0;
}
static void i2cp_cmd_set_name_suffix_data_destroyer(void *data)
{
kfree(data);
}
static int i2cp_cmd_set_name_suffix_header_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
return 1;
}
static int i2cp_cmd_set_name_suffix_data_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
size_t remaining;
struct i2cp_cmd_set_name_suffix_data *cmd_data;
cmd_data = data;
remaining = sizeof(cmd_data->name_suffix) - cmd_data->name_suffix_len;
/* Quietly truncate the suffix if necessary. */
/* The suffix may need to be further truncated later. */
if (in_size > remaining)
in_size = remaining;
memcpy(&cmd_data->name_suffix[cmd_data->name_suffix_len], in, in_size);
cmd_data->name_suffix_len += in_size;
return 0;
}
static int i2cp_cmd_set_name_suffix_cmd_completer(void *data,
struct i2cp_controller *pdata, int receive_status, bool non_blocking)
{
int ret;
struct i2cp_cmd_set_name_suffix_data *cmd_data;
/* Abort if there were errors processing this command. */
if (receive_status)
return 0;
/*
* Acquire pdata->startstop_lock manually instead of using
* i2cp_adap_get_state() in order to keep the lock while
* setting the I2C adapter name.
*/
mutex_lock(&pdata->startstop_lock);
if (pdata->startstop_state != I2CP_CTRLR_STATE_NEW) {
ret = -EISCONN;
goto unlock;
}
cmd_data = data;
ret = snprintf(pdata->i2c_adapter.name, sizeof(pdata->i2c_adapter.name),
"I2C pseudo ID %u %*s", pdata->id,
(int)cmd_data->name_suffix_len, cmd_data->name_suffix);
if (ret < 0)
goto unlock;
ret = 0;
unlock:
mutex_unlock(&pdata->startstop_lock);
return ret;
}
static int i2cp_cmd_set_timeout_data_creator(void **data)
{
struct i2cp_cmd_set_timeout_data *cmd_data;
cmd_data = kzalloc(sizeof(*cmd_data), GFP_KERNEL);
if (!cmd_data)
return -ENOMEM;
*data = cmd_data;
return 0;
}
static void i2cp_cmd_set_timeout_data_destroyer(void *data)
{
kfree(data);
}
static int i2cp_cmd_set_timeout_header_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
int ret;
struct i2cp_cmd_set_timeout_data *cmd_data;
cmd_data = data;
switch (cmd_data->field_pos++) {
case 0:
return 0;
case 1:
ret = kstrtouint(in, 0, &cmd_data->timeout_ms);
if (ret < 0)
return ret;
return 1;
}
/* Reaching here is a bug. */
return -EINVAL;
}
static int i2cp_cmd_set_timeout_data_receiver(void *data, char *in,
size_t in_size, bool non_blocking)
{
/*
* Reaching here means the controller wrote extra data in the command
* line. That is unexpected and indicates a controller bug.
*/
return -EPROTO;
}
static int i2cp_cmd_set_timeout_cmd_completer(void *data,
struct i2cp_controller *pdata, int receive_status, bool non_blocking)
{
int ret;
struct i2cp_cmd_set_timeout_data *cmd_data;
/* Abort if there were errors processing this command. */
if (receive_status)
return 0;
/*
* Acquire pdata->startstop_lock manually instead of using
* i2cp_adap_get_state() in order to keep the lock while setting the
* I2C adapter name.
*/
mutex_lock(&pdata->startstop_lock);
if (pdata->startstop_state != I2CP_CTRLR_STATE_NEW) {
ret = -EISCONN;
goto unlock;
}
cmd_data = data;
if (cmd_data->timeout_ms < I2CP_TIMEOUT_MS_MIN ||
cmd_data->timeout_ms > I2CP_TIMEOUT_MS_MAX) {
ret = -ERANGE;
goto unlock;
}
pdata->i2c_adapter.timeout = msecs_to_jiffies(cmd_data->timeout_ms);
ret = 0;
unlock:
mutex_unlock(&pdata->startstop_lock);
return ret;
}
/* Command names are matched in this order, so sort by expected frequency. */
/* All elements should be initialized in their I2CP_CMD_*_IDX position. */
static const struct i2cp_cmd i2cp_cmds[] = {
[I2CP_CMD_MXFER_REPLY_IDX] = {
.cmd_string = I2CP_MXFER_REPLY_CMD,
.cmd_size = strlen(I2CP_MXFER_REPLY_CMD),
.data_creator = i2cp_cmd_mxfer_reply_data_creator,
.data_shutdown = i2cp_cmd_mxfer_reply_data_shutdown,
.data_destroyer = i2cp_cmd_mxfer_reply_data_destroyer,
.header_receiver = i2cp_cmd_mxfer_reply_header_receiver,
.data_receiver = i2cp_cmd_mxfer_reply_data_receiver,
.cmd_completer = i2cp_cmd_mxfer_reply_cmd_completer,
},
[I2CP_CMD_ADAP_START_IDX] = {
.cmd_string = I2CP_ADAP_START_CMD,
.cmd_size = strlen(I2CP_ADAP_START_CMD),
.header_receiver = i2cp_cmd_adap_start_header_receiver,
.data_receiver = i2cp_cmd_adap_start_data_receiver,
.cmd_completer = i2cp_cmd_adap_start_cmd_completer,
},
[I2CP_CMD_ADAP_SHUTDOWN_IDX] = {
.cmd_string = I2CP_ADAP_SHUTDOWN_CMD,
.cmd_size = strlen(I2CP_ADAP_SHUTDOWN_CMD),
.header_receiver = i2cp_cmd_adap_shutdown_header_receiver,
.data_receiver = i2cp_cmd_adap_shutdown_data_receiver,
.cmd_completer = i2cp_cmd_adap_shutdown_cmd_completer,
},
[I2CP_CMD_GET_NUMBER_IDX] = {
.cmd_string = I2CP_GET_NUMBER_CMD,
.cmd_size = strlen(I2CP_GET_NUMBER_CMD),
.header_receiver = i2cp_cmd_get_number_header_receiver,
.data_receiver = i2cp_cmd_get_number_data_receiver,
.cmd_completer = i2cp_cmd_get_number_cmd_completer,
},
[I2CP_CMD_GET_PSEUDO_ID_IDX] = {
.cmd_string = I2CP_GET_PSEUDO_ID_CMD,
.cmd_size = strlen(I2CP_GET_PSEUDO_ID_CMD),
.header_receiver = i2cp_cmd_get_pseudo_id_header_receiver,
.data_receiver = i2cp_cmd_get_pseudo_id_data_receiver,
.cmd_completer = i2cp_cmd_get_pseudo_id_cmd_completer,
},
[I2CP_CMD_SET_NAME_SUFFIX_IDX] = {
.cmd_string = I2CP_SET_NAME_SUFFIX_CMD,
.cmd_size = strlen(I2CP_SET_NAME_SUFFIX_CMD),
.data_creator = i2cp_cmd_set_name_suffix_data_creator,
.data_destroyer = i2cp_cmd_set_name_suffix_data_destroyer,
.header_receiver = i2cp_cmd_set_name_suffix_header_receiver,
.data_receiver = i2cp_cmd_set_name_suffix_data_receiver,
.cmd_completer = i2cp_cmd_set_name_suffix_cmd_completer,
},
[I2CP_CMD_SET_TIMEOUT_IDX] = {
.cmd_string = I2CP_SET_TIMEOUT_CMD,
.cmd_size = strlen(I2CP_SET_TIMEOUT_CMD),
.data_creator = i2cp_cmd_set_timeout_data_creator,
.data_destroyer = i2cp_cmd_set_timeout_data_destroyer,
.header_receiver = i2cp_cmd_set_timeout_header_receiver,
.data_receiver = i2cp_cmd_set_timeout_data_receiver,
.cmd_completer = i2cp_cmd_set_timeout_cmd_completer,
},
};
/* Returns whether or not there is response queue data to read. */
/* Must be called with pdata->rsp_lock held. */
static inline bool i2cp_poll_in(struct i2cp_controller *pdata)
{
return pdata->rsp_invalidated || pdata->rsp_buf_remaining != 0 ||
!list_empty(&pdata->read_rsp_queue_head);
}
static inline int i2cp_fill_rsp_buf(struct i2cp_rsp *rsp_wrapper,
struct i2cp_rsp_buffer *rsp_buf, char *contents, size_t size)
{
rsp_buf->buf = kmemdup(contents, size, GFP_KERNEL);
if (!rsp_buf->buf)
return -ENOMEM;
rsp_buf->size = size;
rsp_wrapper->data = rsp_buf;
rsp_wrapper->formatter = i2cp_rsp_buffer_formatter;
return 0;
}
#define I2CP_FILL_RSP_BUF_WITH_LITERAL(rsp_wrapper, rsp_buf, str_literal)\
i2cp_fill_rsp_buf(\
rsp_wrapper, rsp_buf, str_literal, strlen(str_literal))
static int i2cp_adapter_master_xfer(struct i2c_adapter *adap,
struct i2c_msg *msgs, int num)
{
int i, ret = 0;
long wait_ret;
size_t wrappers_length, wrapper_idx = 0, rsp_bufs_idx = 0;
struct i2cp_controller *pdata;
struct i2cp_rsp **rsp_wrappers;
struct i2cp_rsp_buffer *rsp_bufs[2] = {0};
struct i2cp_rsp_master_xfer *mxfer_rsp;
struct i2cp_cmd_mxfer_reply_data *cmd_data;
struct i2cp_cmd_mxfer_reply *mxfer_reply;
if (num <= 0) {
if (num < 0)
return -EINVAL;
return ret;
}
pdata = adap->algo_data;
cmd_data = pdata->cmd_data[I2CP_CMD_MXFER_REPLY_IDX];
switch (i2cp_adap_get_state(pdata)) {
case I2CP_CTRLR_STATE_RUNNING:
break;
case I2CP_CTRLR_STATE_SHUTDN_REQ:
return ret;
default:
/* Reaching here is a bug, even with a valid enum value. */
return -EINVAL;
}
wrappers_length = (size_t)num + ARRAY_SIZE(rsp_bufs);
rsp_wrappers = kcalloc(wrappers_length, sizeof(*rsp_wrappers),
GFP_KERNEL);
if (!rsp_wrappers)
return -ENOMEM;
mxfer_reply = kzalloc(sizeof(*mxfer_reply), GFP_KERNEL);
if (!mxfer_reply) {
ret = -ENOMEM;
goto return_after_rsp_wrappers_ptrs_alloc;
}
mxfer_reply->num_msgs = num;
init_completion(&mxfer_reply->data_filled);
mutex_init(&mxfer_reply->lock);
mxfer_reply->msgs = kcalloc(num, sizeof(*mxfer_reply->msgs),
GFP_KERNEL);
if (!mxfer_reply->msgs) {
ret = -ENOMEM;
goto return_after_mxfer_reply_alloc;
}
mxfer_reply->completed = kcalloc(num, sizeof(*mxfer_reply->completed),
GFP_KERNEL);
if (!mxfer_reply->completed) {
ret = -ENOMEM;
goto return_after_reply_msgs_alloc;
}
for (i = 0; i < num; ++i) {
mxfer_reply->msgs[i].addr = msgs[i].addr;
mxfer_reply->msgs[i].flags = msgs[i].flags;
mxfer_reply->msgs[i].len = msgs[i].len;
if (msgs[i].flags & I2C_M_RD)
/* Copy the address, not the data. */
mxfer_reply->msgs[i].buf = msgs[i].buf;
}
for (i = 0; i < ARRAY_SIZE(rsp_bufs); ++i) {
rsp_bufs[i] = kzalloc(sizeof(*rsp_bufs[i]), GFP_KERNEL);
if (!rsp_bufs[i]) {
ret = -ENOMEM;
goto return_after_reply_completed_alloc;
}
}
mxfer_rsp = kzalloc(sizeof(*mxfer_rsp), GFP_KERNEL);
if (!mxfer_rsp) {
ret = -ENOMEM;
goto fail_after_individual_rsp_bufs_alloc;
}
mxfer_rsp->id = cmd_data->next_mxfer_id++;
mxfer_rsp->num = num;
mxfer_rsp->msgs = kcalloc(num, sizeof(*mxfer_rsp->msgs), GFP_KERNEL);
if (!mxfer_rsp->msgs) {
ret = -ENOMEM;
goto fail_after_mxfer_rsp_alloc;
}
for (i = 0; i < num; ++i) {
mxfer_rsp->msgs[i].addr = msgs[i].addr;
mxfer_rsp->msgs[i].flags = msgs[i].flags;
mxfer_rsp->msgs[i].len = msgs[i].len;
if (msgs[i].flags & I2C_M_RD)
continue;
/* Copy the data, not the address. */
mxfer_rsp->msgs[i].buf = kmemdup(msgs[i].buf, msgs[i].len,
GFP_KERNEL);
if (!mxfer_rsp->msgs[i].buf) {
ret = -ENOMEM;
goto fail_after_rsp_msgs_alloc;
}
}
for (i = 0; i < wrappers_length; ++i) {
rsp_wrappers[i] = kzalloc(sizeof(*rsp_wrappers[i]), GFP_KERNEL);
if (!rsp_wrappers[i]) {
ret = -ENOMEM;
goto fail_after_individual_rsp_wrappers_alloc;
}
}
ret = I2CP_FILL_RSP_BUF_WITH_LITERAL(rsp_wrappers[wrapper_idx++],
rsp_bufs[rsp_bufs_idx++], I2CP_BEGIN_MXFER_REQ_CMD);
if (ret < 0)
goto fail_after_individual_rsp_wrappers_alloc;
for (i = 0; i < num; ++i) {
rsp_wrappers[wrapper_idx]->data = mxfer_rsp;
rsp_wrappers[wrapper_idx++]->formatter =
i2cp_rsp_master_xfer_formatter;
}
ret = I2CP_FILL_RSP_BUF_WITH_LITERAL(rsp_wrappers[wrapper_idx++],
rsp_bufs[rsp_bufs_idx++], I2CP_COMMIT_MXFER_REQ_CMD);
if (ret < 0)
goto fail_after_individual_rsp_wrappers_alloc;
BUILD_BUG_ON(rsp_bufs_idx != ARRAY_SIZE(rsp_bufs));
mutex_lock(&pdata->read_rsp_queue_lock);
if (pdata->read_rsp_queue_length >= I2CP_CTRLR_RSP_QUEUE_LIMIT) {
ret = -ENOBUFS;
goto fail_with_read_rsp_queue_lock;
}
mutex_lock(&cmd_data->reply_queue_lock);
if (cmd_data->reply_queue_length >= I2CP_CTRLR_RSP_QUEUE_LIMIT) {
ret = -ENOBUFS;
goto fail_with_reply_queue_lock;
}
mxfer_reply->id = mxfer_rsp->id;
list_add_tail(&mxfer_reply->reply_queue_item,
&cmd_data->reply_queue_head);
++cmd_data->reply_queue_length;
for (i = 0; i < wrappers_length; ++i) {
list_add_tail(&rsp_wrappers[i]->queue,
&pdata->read_rsp_queue_head);
complete(&pdata->read_rsp_queued);
}
pdata->read_rsp_queue_length += wrappers_length;
mutex_unlock(&cmd_data->reply_queue_lock);
mutex_unlock(&pdata->read_rsp_queue_lock);
/* Wake up the userspace controller if it was polling. */
wake_up_interruptible(&pdata->poll_wait_queue);
/* Wait for a response from the userspace controller. */
wait_ret = wait_for_completion_killable_timeout(
&mxfer_reply->data_filled, adap->timeout);
mutex_lock(&cmd_data->reply_queue_lock);
/*
* Ensure mxfer_reply is not in use before dequeuing and freeing it.
* This depends on the requirement that mxfer_reply->lock only be
* acquired while holding cmd_data->reply_queue_lock.
*/
mutex_lock(&mxfer_reply->lock);
if (wait_ret == -ERESTARTSYS)
ret = -EINTR;
else if (wait_ret < 0)
ret = wait_ret;
else
ret = mxfer_reply->ret;
/*
* This depends on other functions that might delete
* mxfer_reply->reply_queue_item from cmd_data->reply_queue_head using
* list_del_init(), never list_del().
*/
if (!list_empty(&mxfer_reply->reply_queue_item)) {
list_del(&mxfer_reply->reply_queue_item);
--cmd_data->reply_queue_length;
if (mxfer_reply == cmd_data->reply_queue_current_item)
cmd_data->reply_queue_current_item = NULL;
}
mutex_unlock(&mxfer_reply->lock);
mutex_unlock(&cmd_data->reply_queue_lock);
goto return_after_reply_msgs_alloc;
fail_with_reply_queue_lock:
mutex_unlock(&cmd_data->reply_queue_lock);
fail_with_read_rsp_queue_lock:
mutex_unlock(&pdata->read_rsp_queue_lock);
fail_after_individual_rsp_wrappers_alloc:
for (i = 0; i < wrappers_length; ++i)
kfree(rsp_wrappers[i]);
fail_after_rsp_msgs_alloc:
for (i = 0; i < num; ++i)
kfree(mxfer_rsp->msgs[i].buf);
kfree(mxfer_rsp->msgs);
fail_after_mxfer_rsp_alloc:
kfree(mxfer_rsp);
fail_after_individual_rsp_bufs_alloc:
for (i = 0; i < ARRAY_SIZE(rsp_bufs); ++i) {
kfree(rsp_bufs[i]->buf);
kfree(rsp_bufs[i]);
}
return_after_reply_completed_alloc:
kfree(mxfer_reply->completed);
return_after_reply_msgs_alloc:
kfree(mxfer_reply->msgs);
return_after_mxfer_reply_alloc:
kfree(mxfer_reply);
return_after_rsp_wrappers_ptrs_alloc:
kfree(rsp_wrappers);
return ret;
}
/*
* If more functionality than this needs to be supported, add a write command
* for the controller to specify its additional functionality prior to
* ADAPTER_START. Basic I2C functionality should remain implied and required.
*
* These functionalities in particular could be worth supporting:
* I2C_FUNC_10BIT_ADDR
* I2C_FUNC_NOSTART
* I2C_FUNC_PROTOCOL_MANGLING
*/
static u32 i2cp_adapter_functionality(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static const struct i2c_algorithm i2cp_algorithm = {
.master_xfer = i2cp_adapter_master_xfer,
.functionality = i2cp_adapter_functionality,
};
/* this_pseudo->counters.lock must _not_ be held when calling this. */
static void i2cp_remove_from_counters(struct i2cp_controller *pdata,
struct i2cp_device *this_pseudo)
{
mutex_lock(&this_pseudo->counters.lock);
this_pseudo->counters.all_controllers[pdata->index] = NULL;
--this_pseudo->counters.count;
mutex_unlock(&this_pseudo->counters.lock);
}
static int i2cp_cdev_open(struct inode *inodep, struct file *filep)
{
int ret = 0;
unsigned int i, num_cmd_data_created = 0;
unsigned int ctrlr_id;
struct i2cp_controller *pdata;
struct i2cp_device *this_pseudo;
/* Is there any way to find this through @inodep? */
this_pseudo = i2cp_device;
/* I2C pseudo adapter controllers are not seekable. */
nonseekable_open(inodep, filep);
/* Refuse fsnotify events. Modeled after /dev/ptmx implementation. */
filep->f_mode |= FMODE_NONOTIFY;
/* Allocate the I2C adapter. */
pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
if (!pdata)
return -ENOMEM;
INIT_LIST_HEAD(&pdata->read_rsp_queue_head);
init_waitqueue_head(&pdata->poll_wait_queue);
init_completion(&pdata->read_rsp_queued);
mutex_init(&pdata->startstop_lock);
mutex_init(&pdata->cmd_lock);
mutex_init(&pdata->rsp_lock);
mutex_init(&pdata->read_rsp_queue_lock);
for (i = 0; i < ARRAY_SIZE(i2cp_cmds); ++i) {
if (!i2cp_cmds[i].data_creator)
continue;
ret = i2cp_cmds[i].data_creator(&pdata->cmd_data[i]);
if (ret < 0)
break;
}
num_cmd_data_created = i;
if (ret < 0)
goto fail_after_cmd_data_created;
mutex_lock(&this_pseudo->counters.lock);
for (i = 0; i < i2cp_limit; ++i)
if (!this_pseudo->counters.all_controllers[i])
break;
if (i >= i2cp_limit) {
mutex_unlock(&this_pseudo->counters.lock);
ret = -ENOSPC;
goto fail_after_cmd_data_created;
}
pdata->index = i;
for (ctrlr_id = this_pseudo->counters.next_ctrlr_id;;) {
/* Determine whether ctrlr_id is already in use. */
for (i = 0; i < i2cp_limit; ++i) {
if (this_pseudo->counters.all_controllers[i] &&
(this_pseudo->counters.all_controllers[i]->id ==
ctrlr_id))
break;
}
/* If ctrlr_id is available, use it. */
if (i >= i2cp_limit) {
pdata->id = ctrlr_id;
this_pseudo->counters.next_ctrlr_id = ctrlr_id + 1;
++this_pseudo->counters.count;
this_pseudo->counters.all_controllers[pdata->index] =
pdata;
break;
}
/* Increment ctrlr_id, and check for wrapping. */
if (++ctrlr_id == this_pseudo->counters.next_ctrlr_id) {
mutex_unlock(&this_pseudo->counters.lock);
ret = -ENOSPC;
goto fail_after_cmd_data_created;
}
}
mutex_unlock(&this_pseudo->counters.lock);
/* Initialize the I2C adapter. */
pdata->i2c_adapter.owner = THIS_MODULE;
pdata->i2c_adapter.class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
pdata->i2c_adapter.algo = &i2cp_algorithm;
pdata->i2c_adapter.algo_data = pdata;
pdata->i2c_adapter.timeout = msecs_to_jiffies(i2cp_default_timeout_ms);
pdata->i2c_adapter.dev.parent = &this_pseudo->device;
ret = snprintf(pdata->i2c_adapter.name, sizeof(pdata->i2c_adapter.name),
"I2C pseudo ID %u", pdata->id);
if (ret < 0)
goto fail_after_counters_update;
/* Return success. */
filep->private_data = pdata;
return 0;
fail_after_counters_update:
i2cp_remove_from_counters(pdata, this_pseudo);
fail_after_cmd_data_created:
for (i = 0; i < num_cmd_data_created; ++i)
if (i2cp_cmds[i].data_destroyer)
i2cp_cmds[i].data_destroyer(pdata->cmd_data[i]);
kfree(pdata);
return ret;
}
static int i2cp_cdev_release(struct inode *inodep, struct file *filep)
{
int i;
bool adapter_was_added = false;
struct i2cp_controller *pdata;
struct i2cp_device *this_pseudo;
pdata = filep->private_data;
this_pseudo = container_of(pdata->i2c_adapter.dev.parent,
struct i2cp_device, device);
/*
* The select(2) man page makes it clear that the behavior of pending
* select()/poll()/epoll_wait() on a fd that gets closed while waiting
* is undefined and should never be relied on. However since we are
* about to free pdata and therefore free pdata->poll_wait_queue, safest
* to wake up anyone waiting on it in an attempt to not leave them in a
* completely undefined state.
*/
wake_up_interruptible_all(&pdata->poll_wait_queue);
/*
* Linux guarantees there are no outstanding reads or writes when a
* struct file is released, so no further synchronization with the other
* struct file_operations callbacks should be needed.
*/
filep->private_data = NULL;
mutex_lock(&pdata->startstop_lock);
if (pdata->startstop_state != I2CP_CTRLR_STATE_NEW) {
/*
* Defer deleting the adapter until after releasing
* pdata->startstop_state. This avoids deadlocking with any
* overlapping i2cp_adapter_master_xfer() calls, which also
* acquire the lock in order to check the state.
*/
adapter_was_added = true;
/*
* Instruct any overlapping i2cp_adapter_master_xfer() calls to
* return immediately.
*/
pdata->startstop_state = I2CP_CTRLR_STATE_SHUTDN_REQ;
}
mutex_unlock(&pdata->startstop_lock);
/*
* Wake up blocked I2C requests. This is an optimization so that they
* don't need to wait for the I2C adapter timeout, since there is no
* possibility of any further I2C replies.
*/
for (i = 0; i < ARRAY_SIZE(i2cp_cmds); ++i)
if (i2cp_cmds[i].data_shutdown)
i2cp_cmds[i].data_shutdown(pdata->cmd_data[i]);
if (adapter_was_added)
i2c_del_adapter(&pdata->i2c_adapter);
for (i = 0; i < ARRAY_SIZE(i2cp_cmds); ++i) {
if (i2cp_cmds[i].data_destroyer)
i2cp_cmds[i].data_destroyer(pdata->cmd_data[i]);
pdata->cmd_data[i] = NULL;
}
i2cp_remove_from_counters(pdata, this_pseudo);
kfree(pdata);
return 0;
}
/* The caller must hold pdata->rsp_lock. */
/* Return value is whether or not to continue in calling loop. */
static bool i2cp_cdev_read_iteration(char __user **buf, size_t *count,
ssize_t *ret, bool non_blocking, struct i2cp_controller *pdata)
{
long wait_ret;
ssize_t copy_size;
unsigned long copy_ret;
struct i2cp_rsp *rsp_wrapper = NULL;
/*
* If a previous read response buffer has been exhausted, free
* it.
*
* This is done at the beginning of the while(count>0) loop
* because...?
*/
if (pdata->rsp_buf_start && !pdata->rsp_buf_remaining) {
kfree(pdata->rsp_buf_start);
pdata->rsp_buf_start = NULL;
pdata->rsp_buf_pos = NULL;
}
/*
* If we have no formatter callback output queued (neither
* successful output nor error), go through the FIFO queue of
* read responses until a formatter returns non-zero (successful
* output or failure).
*/
while (pdata->rsp_buf_remaining == 0) {
/*
* If pdata->rsp_invalidated is true, it means the
* previous read() returned an error. Now that the
* error has already been propagated to userspace, we
* can write the end character for the invalidated read
* response.
*/
if (pdata->rsp_invalidated) {
pdata->rsp_invalidated = false;
goto write_end_char;
}
/* If we have already read some bytes successfully, even
* if less than requested, we should return as much as
* we can without blocking further. Same if we have an
* error to return.
*/
if (non_blocking || *ret != 0) {
if (!try_wait_for_completion(&pdata->read_rsp_queued)) {
if (*ret == 0)
*ret = -EAGAIN;
/*
* If we are out of read responses,
* return whatever we have written to
* the userspace buffer so far, even if
* it's nothing.
*/
return false;
}
} else {
wait_ret = wait_for_completion_killable(
&pdata->read_rsp_queued);
if (wait_ret == -ERESTARTSYS) {
if (*ret == 0)
*ret = -EINTR;
return false;
} else if (wait_ret < 0) {
if (*ret == 0)
*ret = wait_ret;
return false;
}
}
mutex_lock(&pdata->read_rsp_queue_lock);
if (!list_empty(&pdata->read_rsp_queue_head))
rsp_wrapper = list_first_entry(
&pdata->read_rsp_queue_head,
struct i2cp_rsp, queue);
/*
* Avoid holding pdata->read_rsp_queue_lock while
* executing a formatter, allocating memory, or doing
* anything else that might block or take non-trivial
* time. This avoids blocking the enqueuing of new read
* responses for any significant time, even during large
* controller reads.
*/
mutex_unlock(&pdata->read_rsp_queue_lock);
if (!rsp_wrapper) {
/* This should only happen if shutdown was requested. */
if (i2cp_adap_get_state(pdata) !=
I2CP_CTRLR_STATE_SHUTDN_REQ)
*ret = -EINVAL;
return false;
}
pdata->rsp_buf_remaining = rsp_wrapper->formatter(
rsp_wrapper->data, &pdata->rsp_buf_start);
if (pdata->rsp_buf_remaining > 0) {
pdata->rsp_buf_pos = pdata->rsp_buf_start;
/*
* We consumed a completion for this rsp_wrapper
* but we are leaving it in
* pdata->read_rsp_queue_head. Re-add a
* completion for it.
*
* Since overlapping reads are effectively
* serialized via use of pdata->rsp_lock, we
* could take shortcuts in how
* pdata->read_rsp_queued is used to avoid the
* need for re-incrementing it here. However by
* maintaining the invariant of consuming a
* completion each time an item from
* pdata->read_rsp_queue_head is consumed
* (whether or not it ends up being removed from
* the queue in that iteration), the completion
* logic is simpler to follow, and more easily
* lends itself to a future refactor of this
* read operation to not hold pdata->rsp_lock
* continuously.
*/
complete(&pdata->read_rsp_queued);
break;
}
/*
* The formatter should not mutate pdata->rsp_buf_start
* if it returned non-positive. Just in case, we handle
* such a bug gracefully here.
*/
kfree(pdata->rsp_buf_start);
pdata->rsp_buf_start = NULL;
mutex_lock(&pdata->read_rsp_queue_lock);
list_del(&rsp_wrapper->queue);
--pdata->read_rsp_queue_length;
mutex_unlock(&pdata->read_rsp_queue_lock);
kfree(rsp_wrapper);
rsp_wrapper = NULL;
/* Check if the formatter callback returned an error.
*
* If we have _not_ written any bytes to the userspace
* buffer yet, return now with the error code from the
* formatter.
*
* If we _have_ written bytes already, return now with
* the number of bytes written, and leave the error code
* from the formatter in pdata->rsp_buf_remaining so it
* can be returned on the next read, before any bytes
* are written.
*
* In either case, we deliberately return the error
* before writing the end character for the invalidated
* read response, so that the userspace controller knows
* to discard the response.
*/
if (pdata->rsp_buf_remaining < 0) {
if (*ret == 0) {
*ret = pdata->rsp_buf_remaining;
pdata->rsp_buf_remaining = 0;
}
pdata->rsp_invalidated = true;
return false;
}
write_end_char:
copy_size = sizeof(i2cp_ctrlr_end_char);
/*
* This assertion is just in case someone changes
* i2cp_ctrlr_end_char to a string. Such a change would require
* handling it like a read response buffer, including ensuring
* that we not write more than *count. So long as it's a single
* character, we can avoid an extra check of *count in this code
* block, we already know it's greater than zero.
*/
BUILD_BUG_ON(copy_size != 1);
copy_ret = copy_to_user(*buf, &i2cp_ctrlr_end_char,
copy_size);
copy_size -= copy_ret;
/*
* After writing to the userspace buffer, we need to
* update various counters including the return value,
* then continue from the start of the outer while loop
* because it's possible *count has reached zero.
*
* Those exact same steps must be done after copying
* from a read response buffer to the userspace buffer,
* so jump to that code instead of duplicating it.
*/
goto after_copy_to_user;
}
copy_size = max_t(ssize_t, 0,
min_t(ssize_t, *count, pdata->rsp_buf_remaining));
copy_ret = copy_to_user(*buf, pdata->rsp_buf_pos, copy_size);
copy_size -= copy_ret;
pdata->rsp_buf_remaining -= copy_size;
if (pdata->rsp_buf_remaining > 0) {
pdata->rsp_buf_pos += copy_size;
} else {
kfree(pdata->rsp_buf_start);
pdata->rsp_buf_start = NULL;
pdata->rsp_buf_pos = NULL;
}
/*
* When jumping here, the following variables should be set:
* copy_ret: Return value from copy_to_user() (bytes not copied).
* copy_size: The number of bytes successfully copied by copy_to_user(). In
* other words, this should be the size arg to copy_to_user() minus its
* return value (bytes not copied).
*/
after_copy_to_user:
*ret += copy_size;
*count -= copy_size;
*buf += copy_size;
return !copy_ret;
}
static ssize_t i2cp_cdev_read(struct file *filep, char __user *buf,
size_t count, loff_t *f_ps)
{
ssize_t ret = 0;
bool non_blocking;
struct i2cp_controller *pdata;
/*
* Just in case this could change out from under us, best to keep a
* consistent view for the duration of this syscall.
*/
non_blocking = !!(filep->f_flags & O_NONBLOCK);
pdata = filep->private_data;
if (count > (size_t)I2CP_RW_SIZE_LIMIT)
count = I2CP_RW_SIZE_LIMIT;
/*
* Since read() calls are effectively serialized by way of
* pdata->rsp_lock, we MUST NOT block on obtaining that lock if in
* non-blocking mode, because it might be held by a blocking read().
*/
if (!non_blocking)
mutex_lock(&pdata->rsp_lock);
else if (!mutex_trylock(&pdata->rsp_lock))
return -EAGAIN;
/*
* Check if a formatter callback returned an error that hasn't yet been
* returned to the controller. Do this before the while(count>0) loop
* because read(2) with zero count is allowed to report errors.
*/
if (pdata->rsp_buf_remaining < 0) {
BUILD_BUG_ON(ret != 0);
ret = pdata->rsp_buf_remaining;
pdata->rsp_buf_remaining = 0;
goto unlock;
}
while (count > 0 && i2cp_cdev_read_iteration(
&buf, &count, &ret, non_blocking, pdata))
;
unlock:
mutex_unlock(&pdata->rsp_lock);
return ret;
}
/* Must be called with pdata->cmd_lock held. */
/* Must never consume past first i2cp_ctrlr_end_char in @start. */
static ssize_t i2cp_receive_ctrlr_cmd_header(
struct i2cp_controller *pdata, char *start, size_t remaining,
bool non_blocking)
{
int found_deliminator_char = 0;
int i, cmd_idx;
ssize_t copy_size, ret = 0, stop, buf_remaining;
buf_remaining = I2CP_CTRLR_CMD_LIMIT - pdata->cmd_size;
stop = min_t(ssize_t, remaining, buf_remaining + 1);
for (i = 0; i < stop; ++i)
if (start[i] == i2cp_ctrlr_end_char ||
start[i] == i2cp_ctrlr_header_sep_char) {
found_deliminator_char = 1;
break;
}
if (i <= buf_remaining) {
copy_size = i;
} else {
copy_size = buf_remaining;
if (!pdata->cmd_receive_status)
/*
* Exceeded max size of I2C pseudo controller command
* buffer. The command currently being written will be
* ignored.
*
* Positive error number is deliberate here.
*/
pdata->cmd_receive_status = ENOBUFS;
}
memcpy(&pdata->cmd_buf[pdata->cmd_size], start, copy_size);
pdata->cmd_size += copy_size;
if (!found_deliminator_char || pdata->cmd_size <= 0)
return copy_size + found_deliminator_char;
/* This may be negative. */
cmd_idx = pdata->cmd_idx_plus_one - 1;
if (cmd_idx < 0) {
for (i = 0; i < ARRAY_SIZE(i2cp_cmds); ++i)
if (i2cp_cmds[i].cmd_size == pdata->cmd_size &&
!memcmp(i2cp_cmds[i].cmd_string, pdata->cmd_buf,
pdata->cmd_size))
break;
if (i >= ARRAY_SIZE(i2cp_cmds)) {
/* unrecognized command */
ret = -EIO;
goto clear_buffer;
}
cmd_idx = i;
pdata->cmd_idx_plus_one = cmd_idx + 1;
}
/*
* If we have write bytes queued and we encountered i2cp_ctrlr_end_char
* or i2cp_ctrlr_header_sep_char, invoke the header_receiver callback.
*/
if (!pdata->cmd_receive_status) {
ret = i2cp_cmds[cmd_idx].header_receiver(
pdata->cmd_data[cmd_idx], pdata->cmd_buf,
pdata->cmd_size, non_blocking);
if (ret > 0) {
if (ret > I2CP_CTRLR_CMD_LIMIT) {
ret = -EINVAL;
goto clear_buffer;
}
pdata->cmd_data_increment = ret;
} else if (ret < 0) {
pdata->cmd_receive_status = ret;
}
}
clear_buffer:
pdata->cmd_size = 0;
/*
* Ensure a trailing null character for the next header_receiver() or
* data_receiver() invocation.
*/
memset(pdata->cmd_buf, 0, sizeof(pdata->cmd_buf));
if (ret < 0) {
if (pdata->cmd_idx_plus_one >= 1 && !pdata->cmd_receive_status)
/* Negate to get a positive error number. */
pdata->cmd_receive_status = -ret;
return ret;
}
return copy_size + found_deliminator_char;
}
/* Must be called with pdata->cmd_lock held. */
/* Must never consume past first i2cp_ctrlr_end_char in @start. */
static ssize_t i2cp_receive_ctrlr_cmd_data(struct i2cp_controller *pdata,
char *start, size_t remaining, bool non_blocking)
{
ssize_t i, ret, size_holder;
int cmd_idx;
/* If cmd_idx ends up negative here, it is a bug. */
cmd_idx = pdata->cmd_idx_plus_one - 1;
if (cmd_idx < 0)
return -EINVAL;
size_holder = min_t(size_t,
(I2CP_CTRLR_CMD_LIMIT -
(I2CP_CTRLR_CMD_LIMIT % pdata->cmd_data_increment)) -
pdata->cmd_size,
(((pdata->cmd_size + remaining) /
pdata->cmd_data_increment) *
pdata->cmd_data_increment) - pdata->cmd_size);
/* Size of current buffer plus all remaining write bytes. */
size_holder = pdata->cmd_size + remaining;
/*
* Avoid rounding down to zero. If there are insufficient write
* bytes remaining to grow the buffer to 1x of the requested
* data byte increment, we'll copy what is available to the
* buffer, and just leave it queued without any further command
* handler invocations in this write() (unless i2cp_ctrlr_end_char is
* found, in which case we will always invoke the data_receiver for any
* remaining data bytes, and will always invoke the cmd_completer).
*/
if (size_holder > pdata->cmd_data_increment)
/*
* Round down to the nearest multiple of the requested
* data byte increment.
*/
size_holder -= size_holder % pdata->cmd_data_increment;
/*
* Take the smaller of:
*
* [A] 2nd min_t() arg: The number of bytes that we would want the
* buffer to end up with if it had unlimited space (computed
* above).
*
* [B] 3rd min_t() arg: The number of bytes that we would want the
* buffer to end up with if there were unlimited write bytes
* remaining (computed in-line below).
*/
size_holder = min_t(ssize_t, size_holder, (I2CP_CTRLR_CMD_LIMIT - (
I2CP_CTRLR_CMD_LIMIT % pdata->cmd_data_increment)));
/*
* Subtract the existing buffer size to get the number of bytes we
* actually want to copy from the remaining write bytes in this loop
* iteration, assuming no i2cp_ctrlr_end_char.
*/
size_holder -= pdata->cmd_size;
/*
* Look for i2cp_ctrlr_end_char. If we find it, we will copy up to but
* *not* including its position.
*/
for (i = 0; i < size_holder; ++i)
if (start[i] == i2cp_ctrlr_end_char)
break;
/* Copy from the remaining write bytes to the command buffer. */
memcpy(&pdata->cmd_buf[pdata->cmd_size], start, i);
pdata->cmd_size += i;
/*
* If we have write bytes queued and *either* we encountered
* i2cp_ctrlr_end_char *or* we have a multiple of
* pdata->cmd_data_increment, invoke the data_receiver callback.
*/
if (pdata->cmd_size > 0 &&
(i < size_holder ||
pdata->cmd_size % pdata->cmd_data_increment == 0)) {
if (!pdata->cmd_receive_status) {
ret = i2cp_cmds[cmd_idx].data_receiver(
pdata->cmd_data[cmd_idx], pdata->cmd_buf,
pdata->cmd_size, non_blocking);
if (ret < 0)
pdata->cmd_receive_status = ret;
}
pdata->cmd_size = 0;
/*
* Ensure a trailing null character for the next
* header_receiver() or data_receiver() invocation.
*/
memset(pdata->cmd_buf, 0, sizeof(pdata->cmd_buf));
}
/* If i2cp_ctrlr_end_char was found, skip past it. */
if (i < size_holder)
++i;
return i;
}
/* Must be called with pdata->cmd_lock held. */
static int i2cp_receive_ctrlr_cmd_complete(struct i2cp_controller *pdata,
bool non_blocking)
{
int ret = 0, cmd_idx;
/* This may be negative. */
cmd_idx = pdata->cmd_idx_plus_one - 1;
if (cmd_idx >= 0 && i2cp_cmds[cmd_idx].cmd_completer) {
ret = i2cp_cmds[cmd_idx].cmd_completer(pdata->cmd_data[cmd_idx],
pdata, pdata->cmd_receive_status, non_blocking);
if (ret > 0)
ret = 0;
}
pdata->cmd_idx_plus_one = 0;
pdata->cmd_receive_status = 0;
pdata->cmd_data_increment = 0;
pdata->cmd_size = 0;
/*
* Ensure a trailing null character for the next header_receiver() or
* data_receiver() invocation.
*/
memset(pdata->cmd_buf, 0, sizeof(pdata->cmd_buf));
return ret;
}
static ssize_t i2cp_cdev_write(struct file *filep, const char __user *buf,
size_t count, loff_t *f_ps)
{
ssize_t ret = 0;
bool non_blocking;
size_t remaining;
char *kbuf, *start;
struct i2cp_controller *pdata;
/*
* Just in case this could change out from under us, best to keep a
* consistent view for the duration of this syscall.
*
* Write command implementations, i.e. struct i2cp_cmd implementations,
* do NOT have to support blocking writes. For example, if a write of
* an I2C message reply is received for a message that the pseudo
* adapter never requested or expected, it makes more sense to indicate
* an error than to block until possibly receiving a master_xfer request
* for that I2C message, even if blocking is permitted.
*
* Furthermore, controller writes MUST NEVER block indefinitely, even
* when non_blocking is false. E.g. while non_blocking may be used to
* select between mutex_trylock and mutex_lock*, even in the
* latter case the lock should never be blocked on I/O, on userspace, or
* on anything else outside the control of this driver. It IS
* permissable for the lock to be blocked on processing of previous or
* concurrent write input, so long as that processing does not violate
* these rules.
*/
non_blocking = !!(filep->f_flags & O_NONBLOCK);
pdata = filep->private_data;
if (count > (size_t)I2CP_RW_SIZE_LIMIT)
count = I2CP_RW_SIZE_LIMIT;
kbuf = kzalloc(count, GFP_KERNEL);
if (!kbuf) {
ret = -ENOMEM;
goto free_kbuf;
}
if (copy_from_user(kbuf, buf, count))
goto free_kbuf;
start = kbuf;
remaining = count;
/*
* Since write() calls are effectively serialized by way of
* pdata->cmd_lock, we MUST NOT block on obtaining that lock if in
* non-blocking mode, because it might be held by a blocking write().
*/
if (!non_blocking) {
mutex_lock(&pdata->cmd_lock);
} else if (!mutex_trylock(&pdata->cmd_lock)) {
ret = -EAGAIN;
goto free_kbuf;
}
while (remaining) {
if (pdata->cmd_data_increment <= 0)
ret = i2cp_receive_ctrlr_cmd_header(
pdata, start, remaining, non_blocking);
else
ret = i2cp_receive_ctrlr_cmd_data(
pdata, start, remaining, non_blocking);
if (ret < 0)
break;
if (ret == 0 || ret > remaining) {
ret = -EINVAL;
break;
}
remaining -= ret;
start += ret;
if (ret > 0 && start[-1] == i2cp_ctrlr_end_char) {
ret = i2cp_receive_ctrlr_cmd_complete(
pdata, non_blocking);
if (ret < 0)
break;
}
}
mutex_unlock(&pdata->cmd_lock);
wake_up_interruptible_sync(&pdata->poll_wait_queue);
if (ret >= 0)
/* If successful the whole write is always consumed. */
ret = count;
free_kbuf:
kfree(kbuf);
return ret;
}
/*
* The select/poll/epoll implementation in this module is designed around these
* controller behavior assumptions:
*
* - If any reader of a given controller makes use of polling, all will.
*
* - Upon notification of available data to read, a reader will fully consume it
* in a read() loop until receiving EAGAIN, EWOULDBLOCK, or EOF.
*
* - Only one reader need be woken upon newly available data, however it is okay
* if more than one are sometimes woken.
*
* - If more than one reader is woken, or otherwise acts in parallel, it is the
* responsibility of the readers to either ensure that only one at a time
* consumes all input until EAGAIN/EWOULDBLOCK, or that they properly
* recombine any data that was split among them.
*
* - All of the above applies to writers as well.
*
* Notes:
*
* - If a reader does not read all available data until EAGAIN/EWOULDBLOCK after
* being woken from poll, there may be no wake event for the remaining
* available data, causing it to remain unread until further data becomes
* available and triggers another wake event. The same applies to writers -
* they are only guaranteed to be woken /once/ per blocked->unblocked
* transition, so after being woken they should continue writing until either
* the controller is out of data or EAGAIN/EWOULDBLOCK is encountered.
*
* - It is strongly suggested that controller implementations have only one
* reader (thread) and one writer (thread), which may or may not be the same
* thread. After all only one message can be active on an I2C bus at a time,
* and this driver implementation reflects that. Avoiding multiple readers
* and multiple writers greatly simplifies controller implementation, and
* there is likely nothing to be gained from performing any of their work in
* parallel.
*
* - Implementation detail: Reads are effectively serialized by a per controller
* read lock. From the perspective of other readers, the controller device
* will appear blocked, with appropriate behavior based on the O_NONBLOCK bit.
* THIS IS SUBJECT TO CHANGE!
*
* - Implementation detail: Writes are effectively serialized by a per
* controller write lock. From the perspective of other writers, the
* controller device will appear blocked, with appropriate behavior based on
* the O_NONBLOCK bit. THIS IS SUBJECT TO CHANGE!
*
* - Implementation detail: In the initial implementation, the only scenario
* where a controller will appear blocked for writes is if another write is in
* progress. Thus, a single writer should never see the device blocked. THIS
* IS SUBJECT TO CHANGE! When using O_NONBLOCK, a controller should correctly
* handle EAGAIN/EWOULDBLOCK even if it has only one writer.
*/
static __poll_t i2cp_cdev_poll(struct file *filep, poll_table *ptp)
{
__poll_t poll_ret = 0;
struct i2cp_controller *pdata;
pdata = filep->private_data;
poll_wait(filep, &pdata->poll_wait_queue, ptp);
if (mutex_trylock(&pdata->rsp_lock)) {
if (i2cp_poll_in(pdata))
poll_ret |= POLLIN | POLLRDNORM;
mutex_unlock(&pdata->rsp_lock);
}
if (!mutex_is_locked(&pdata->cmd_lock))
poll_ret |= POLLOUT | POLLWRNORM;
if (i2cp_adap_get_state(pdata) == I2CP_CTRLR_STATE_SHUTDN_REQ)
poll_ret |= POLLHUP;
return poll_ret;
}
static const struct file_operations i2cp_fileops = {
.owner = THIS_MODULE,
.open = i2cp_cdev_open,
.release = i2cp_cdev_release,
.read = i2cp_cdev_read,
.write = i2cp_cdev_write,
.poll = i2cp_cdev_poll,
.llseek = no_llseek,
};
static ssize_t i2cp_limit_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
int ret;
ret = snprintf(buf, PAGE_SIZE, "%u\n", i2cp_limit);
if (ret >= PAGE_SIZE)
return -ERANGE;
return ret;
}
static struct device_attribute i2cp_limit_dev_attr = {
.attr = {
.name = "limit",
.mode = 0444,
},
.show = i2cp_limit_show,
};
static ssize_t i2cp_count_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
int count, ret;
struct i2cp_device *this_pseudo;
this_pseudo = container_of(dev, struct i2cp_device, device);
mutex_lock(&this_pseudo->counters.lock);
count = this_pseudo->counters.count;
mutex_unlock(&this_pseudo->counters.lock);
ret = snprintf(buf, PAGE_SIZE, "%u\n", count);
if (ret >= PAGE_SIZE)
return -ERANGE;
return ret;
}
static struct device_attribute i2cp_count_dev_attr = {
.attr = {
.name = "count",
.mode = 0444,
},
.show = i2cp_count_show,
};
static struct attribute *i2cp_device_sysfs_attrs[] = {
&i2cp_limit_dev_attr.attr,
&i2cp_count_dev_attr.attr,
NULL,
};
static const struct attribute_group i2cp_device_sysfs_group = {
.attrs = i2cp_device_sysfs_attrs,
};
static const struct attribute_group *i2cp_device_sysfs_groups[] = {
&i2cp_device_sysfs_group,
NULL,
};
static void i2c_p_device_release(struct device *dev)
{
struct i2cp_device *this_pseudo;
this_pseudo = container_of(dev, struct i2cp_device, device);
kfree(this_pseudo->counters.all_controllers);
kfree(this_pseudo);
}
static inline void i2c_p_class_destroy(void)
{
struct class *class;
class = i2cp_class;
i2cp_class = NULL;
class_destroy(class);
}
static int __init i2cp_init(void)
{
int ret = -1;
if (i2cp_limit < I2CP_ADAPTERS_MIN || i2cp_limit > I2CP_ADAPTERS_MAX) {
pr_err("%s: i2cp_limit=%u, must be in range ["
STR(I2CP_ADAPTERS_MIN) ", " STR(I2CP_ADAPTERS_MAX)
"]\n", __func__, i2cp_limit);
return -EINVAL;
}
i2cp_class = class_create(THIS_MODULE, I2CP_CLASS_NAME);
if (IS_ERR(i2cp_class))
return PTR_ERR(i2cp_class);
i2cp_class->dev_groups = i2cp_device_sysfs_groups;
ret = alloc_chrdev_region(&i2cp_dev_num, I2CP_CDEV_BASEMINOR,
I2CP_CDEV_COUNT, I2CP_CHRDEV_NAME);
if (ret < 0)
goto fail_after_class_create;
i2cp_device = kzalloc(sizeof(*i2cp_device), GFP_KERNEL);
if (!i2cp_device) {
ret = -ENOMEM;
goto fail_after_chrdev_register;
}
i2cp_device->device.devt = i2cp_dev_num;
i2cp_device->device.class = i2cp_class;
i2cp_device->device.release = i2c_p_device_release;
device_initialize(&i2cp_device->device);
ret = dev_set_name(&i2cp_device->device, "%s", I2CP_DEVICE_NAME);
if (ret < 0)
goto fail_after_device_init;
mutex_init(&i2cp_device->counters.lock);
i2cp_device->counters.all_controllers = kcalloc(i2cp_limit,
sizeof(*i2cp_device->counters.all_controllers), GFP_KERNEL);
if (!i2cp_device->counters.all_controllers) {
ret = -ENOMEM;
goto fail_after_device_init;
}
cdev_init(&i2cp_device->cdev, &i2cp_fileops);
i2cp_device->cdev.owner = THIS_MODULE;
ret = cdev_device_add(&i2cp_device->cdev, &i2cp_device->device);
if (ret < 0)
goto fail_after_device_init;
return 0;
fail_after_device_init:
put_device(&i2cp_device->device);
fail_after_chrdev_register:
unregister_chrdev_region(i2cp_dev_num, I2CP_CDEV_COUNT);
fail_after_class_create:
i2c_p_class_destroy();
return ret;
}
static void __exit i2cp_exit(void)
{
cdev_device_del(&i2cp_device->cdev, &i2cp_device->device);
put_device(&i2cp_device->device);
unregister_chrdev_region(i2cp_dev_num, I2CP_CDEV_COUNT);
i2c_p_class_destroy();
}
MODULE_AUTHOR("Matthew Blecker <matthewb@ihavethememo.net");
MODULE_DESCRIPTION("Driver for userspace I2C adapter implementations.");
MODULE_LICENSE("GPL");
module_init(i2cp_init);
module_exit(i2cp_exit);