342 lines
7.7 KiB
C
342 lines
7.7 KiB
C
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/* Copyright 2013 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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/*
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* Define CONFIG_CMD_I2CWEDGE and I2C_PORT_HOST to enable the 'i2cwedge'
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* console command to allow us to bang the bus into a wedged state. For
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* example, include the following lines in board/pit/board.h to enable it on
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* pit:
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*
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* #define CONFIG_CMD_I2CWEDGE
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* #define I2C_PORT_HOST I2C_PORT_MASTER
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*
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*/
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#include "console.h"
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#include "gpio.h"
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#include "i2c.h"
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#include "system.h"
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#include "timer.h"
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#include "util.h"
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/*
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* The implementation is based on Wikipedia.
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*/
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int i2c_bang_started;
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static void i2c_bang_delay(void)
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{
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udelay(5);
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}
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static void i2c_bang_start_cond(void)
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{
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/* Restart if needed */
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if (i2c_bang_started) {
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/* set SDA to 1 */
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i2c_raw_set_sda(I2C_PORT_HOST, 1);
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i2c_bang_delay();
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/* Clock stretching */
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i2c_raw_set_scl(I2C_PORT_HOST, 1);
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while (i2c_raw_get_scl(I2C_PORT_HOST) == 0)
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; /* TODO(crosbug.com/p/26487): TIMEOUT */
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/* Repeated start setup time, minimum 4.7us */
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i2c_bang_delay();
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}
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i2c_raw_set_sda(I2C_PORT_HOST, 1);
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if (i2c_raw_get_sda(I2C_PORT_HOST) == 0)
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; /* TODO(crosbug.com/p/26487): arbitration_lost */
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/* SCL is high, set SDA from 1 to 0. */
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i2c_raw_set_sda(I2C_PORT_HOST, 0);
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i2c_bang_delay();
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i2c_raw_set_scl(I2C_PORT_HOST, 0);
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i2c_bang_started = 1;
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ccputs("BITBANG: send start\n");
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}
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static void i2c_bang_stop_cond(void)
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{
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/* set SDA to 0 */
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i2c_raw_set_sda(I2C_PORT_HOST, 0);
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i2c_bang_delay();
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/* Clock stretching */
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i2c_raw_set_scl(I2C_PORT_HOST, 1);
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while (i2c_raw_get_scl(I2C_PORT_HOST) == 0)
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; /* TODO(crosbug.com/p/26487): TIMEOUT */
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/* Stop bit setup time, minimum 4us */
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i2c_bang_delay();
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/* SCL is high, set SDA from 0 to 1 */
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i2c_raw_set_sda(I2C_PORT_HOST, 1);
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if (i2c_raw_get_sda(I2C_PORT_HOST) == 0)
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; /* TODO(crosbug.com/p/26487): arbitration_lost */
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i2c_bang_delay();
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i2c_bang_started = 0;
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ccputs("BITBANG: send stop\n");
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}
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static void i2c_bang_out_bit(int bit)
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{
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if (bit)
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i2c_raw_set_sda(I2C_PORT_HOST, 1);
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else
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i2c_raw_set_sda(I2C_PORT_HOST, 0);
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i2c_bang_delay();
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/* Clock stretching */
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i2c_raw_set_scl(I2C_PORT_HOST, 1);
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while (i2c_raw_get_scl(I2C_PORT_HOST) == 0)
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; /* TODO(crosbug.com/p/26487): TIMEOUT */
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/*
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* SCL is high, now data is valid
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* If SDA is high, check that nobody else is driving SDA
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*/
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i2c_raw_set_sda(I2C_PORT_HOST, 1);
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if (bit && i2c_raw_get_sda(I2C_PORT_HOST) == 0)
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; /* TODO(crosbug.com/p/26487): arbitration_lost */
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i2c_bang_delay();
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i2c_raw_set_scl(I2C_PORT_HOST, 0);
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}
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static int i2c_bang_in_bit(void)
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{
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int bit;
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/* Let the slave drive data */
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i2c_raw_set_sda(I2C_PORT_HOST, 1);
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i2c_bang_delay();
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/* Clock stretching */
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i2c_raw_set_scl(I2C_PORT_HOST, 1);
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while (i2c_raw_get_scl(I2C_PORT_HOST) == 0)
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; /* TODO(crosbug.com/p/26487): TIMEOUT */
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/* SCL is high, now data is valid */
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bit = i2c_raw_get_sda(I2C_PORT_HOST);
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i2c_bang_delay();
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i2c_raw_set_scl(I2C_PORT_HOST, 0);
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return bit;
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}
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/* Write a byte to I2C bus. Return 0 if ack by the slave. */
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static int i2c_bang_out_byte(int send_start, int send_stop, unsigned char byte)
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{
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unsigned bit;
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int nack;
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int tmp = byte;
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if (send_start)
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i2c_bang_start_cond();
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for (bit = 0; bit < 8; bit++) {
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i2c_bang_out_bit((byte & 0x80) != 0);
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byte <<= 1;
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}
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nack = i2c_bang_in_bit();
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ccprintf(" write byte: %d ack/nack=%d\n", tmp, nack);
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if (send_stop)
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i2c_bang_stop_cond();
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return nack;
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}
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static unsigned char i2c_bang_in_byte(int ack, int send_stop)
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{
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unsigned char byte = 0;
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int i;
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for (i = 0; i < 8; ++i)
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byte = (byte << 1) | i2c_bang_in_bit();
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i2c_bang_out_bit(ack != 0);
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if (send_stop)
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i2c_bang_stop_cond();
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return byte;
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}
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static void i2c_bang_init(void)
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{
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i2c_bang_started = 0;
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i2c_raw_mode(I2C_PORT_HOST, 1);
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}
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static void i2c_bang_xfer(int slave_addr, int reg)
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{
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int byte;
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i2c_bang_init();
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/* State a write command to 'slave_addr' */
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i2c_bang_out_byte(1 /*start*/, 0 /*stop*/, slave_addr);
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/* Write 'reg' */
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i2c_bang_out_byte(0 /*start*/, 0 /*stop*/, reg);
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/* Start a read command */
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i2c_bang_out_byte(1 /*start*/, 0 /*stop*/, slave_addr | 1);
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/* Read two bytes */
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byte = i2c_bang_in_byte(0, 0); /* ack and no stop */
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ccprintf(" read byte: %d\n", byte);
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byte = i2c_bang_in_byte(1, 1); /* nack and stop */
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ccprintf(" read byte: %d\n", byte);
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}
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static void i2c_bang_wedge_write(int slave_addr, int byte, int bit_count,
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int reboot)
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{
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int i;
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i2c_bang_init();
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/* State a write command to 'slave_addr' */
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i2c_bang_out_byte(1 /*start*/, 0 /*stop*/, slave_addr);
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/* Send a few bits and stop */
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for (i = 0; i < bit_count; ++i) {
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i2c_bang_out_bit((byte & 0x80) != 0);
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byte <<= 1;
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}
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ccprintf(" wedged write after %d bits\n", bit_count);
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if (reboot)
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system_reset(0);
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}
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static void i2c_bang_wedge_read(int slave_addr, int reg, int bit_count,
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int reboot)
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{
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int i;
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i2c_bang_init();
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/* State a write command to 'slave_addr' */
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i2c_bang_out_byte(1 /*start*/, 0 /*stop*/, slave_addr);
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/* Write 'reg' */
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i2c_bang_out_byte(0 /*start*/, 0 /*stop*/, reg);
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/* Start a read command */
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i2c_bang_out_byte(1 /*start*/, 0 /*stop*/, slave_addr | 1);
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/* Read bit_count bits and stop */
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for (i = 0; i < bit_count; ++i)
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i2c_bang_in_bit();
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ccprintf(" wedged read after %d bits\n", bit_count);
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if (reboot)
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system_reset(0);
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}
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#define WEDGE_WRITE 1
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#define WEDGE_READ 2
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#define WEDGE_REBOOT 4
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static int command_i2c_wedge(int argc, char **argv)
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{
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int slave_addr, reg, wedge_flag = 0, wedge_bit_count = -1;
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char *e;
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enum gpio_signal tmp;
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/* Verify that the I2C_PORT_HOST has SDA and SCL pins defined. */
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if (get_sda_from_i2c_port(I2C_PORT_HOST, &tmp) != EC_SUCCESS ||
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get_scl_from_i2c_port(I2C_PORT_HOST, &tmp) != EC_SUCCESS) {
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ccprintf("Cannot wedge bus because no SCL and SDA pins are"
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"defined for this port. Check i2c_ports[].\n");
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return EC_SUCCESS;
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}
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if (argc < 3) {
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ccputs("Usage: i2cwedge slave_addr out_byte "
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"[wedge_flag [wedge_bit_count]]\n");
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ccputs(" wedge_flag - (1: wedge out; 2: wedge in;"
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" 5: wedge out+reboot; 6: wedge in+reboot)]\n");
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ccputs(" wedge_bit_count - 0 to 8\n");
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return EC_ERROR_UNKNOWN;
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}
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slave_addr = strtoi(argv[1], &e, 0);
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if (*e) {
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ccprintf("Invalid slave_addr %s\n", argv[1]);
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return EC_ERROR_INVAL;
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}
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reg = strtoi(argv[2], &e, 0);
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if (*e) {
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ccprintf("Invalid out_byte %s\n", argv[2]);
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return EC_ERROR_INVAL;
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}
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if (argc > 3) {
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wedge_flag = strtoi(argv[3], &e, 0);
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if (*e) {
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ccprintf("Invalid wedge_flag %s\n", argv[3]);
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return EC_ERROR_INVAL;
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}
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}
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if (argc > 4) {
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wedge_bit_count = strtoi(argv[4], &e, 0);
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if (*e || wedge_bit_count < 0 || wedge_bit_count > 8) {
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ccprintf("Invalid wedge_bit_count %s.\n", argv[4]);
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return EC_ERROR_INVAL;
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}
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}
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i2c_lock(I2C_PORT_HOST, 1);
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if (wedge_flag & WEDGE_WRITE) {
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if (wedge_bit_count < 0)
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wedge_bit_count = 8;
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i2c_bang_wedge_write(slave_addr, reg, wedge_bit_count,
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(wedge_flag & WEDGE_REBOOT));
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} else if (wedge_flag & WEDGE_READ) {
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if (wedge_bit_count < 0)
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wedge_bit_count = 2;
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i2c_bang_wedge_read(slave_addr, reg, wedge_bit_count,
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(wedge_flag & WEDGE_REBOOT));
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} else {
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i2c_bang_xfer(slave_addr, reg);
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}
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/* Put it back into normal mode */
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i2c_raw_mode(I2C_PORT_HOST, 0);
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i2c_lock(I2C_PORT_HOST, 0);
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if (wedge_flag & (WEDGE_WRITE | WEDGE_READ))
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ccprintf("I2C bus %d is now wedged. Enjoy.\n", I2C_PORT_HOST);
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else
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ccprintf("Bit bang xfer complete.\n");
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return EC_SUCCESS;
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}
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DECLARE_CONSOLE_COMMAND(i2cwedge, command_i2c_wedge,
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"i2cwedge slave_addr out_byte "
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"[wedge_flag [wedge_bit_count]]",
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"Wedge host I2C bus");
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static int command_i2c_unwedge(int argc, char **argv)
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{
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i2c_unwedge(I2C_PORT_HOST);
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return EC_SUCCESS;
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}
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DECLARE_CONSOLE_COMMAND(i2cunwedge, command_i2c_unwedge,
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"",
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"Unwedge host I2C bus");
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