ec/purism,system76: Provide probe for fixed Librem-EC jack detect

Provide system76_ec_cmd() to send arbitrary commands to the EC.

Provide librem_ec_has_jack_detect() to probe for the jack detect fix.

Change-Id: Ic7bda0ce230a3ad68dfeb7b01a0e04f70dab9e5d
Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/74390
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Crawford <tcrawford@system76.com>

src/ec/purism/librem-ec/Makefile.inc

@@ -2,6 +2,7 @@
 ifeq ($(CONFIG_EC_LIBREM_EC),y)
 
 all-y += ../../system76/ec/system76_ec.c
+all-y += librem_ec.c
 smm-$(CONFIG_DEBUG_SMI) += ../../system76/ec/system76_ec.c
 
 endif

src/ec/purism/librem-ec/librem_ec.c

@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include "librem_ec.h"
+#include "../../system76/ec/system76_ec.h"
+#include <stddef.h>
+
+#define CMD_PROBE 1
+
+bool librem_ec_has_jack_detect(void)
+{
+	/* The 'flags' field in the probe command reply was added in an update.
+	   Send 4 bytes of zeroes in the "request" to zero out the field if the
+	   EC does not set it for its reply. */
+	const uint8_t request_data[4] = {0};
+	uint8_t reply_data[4] = {0};
+	bool ec_cmd_success = system76_ec_cmd(CMD_PROBE, request_data,
+		ARRAY_SIZE(request_data), reply_data, ARRAY_SIZE(reply_data));
+	if (!ec_cmd_success)
+		return false;
+	/* Byte 3 is flags, bit 0 is the jack detect flag */
+	return reply_data[3] & 0x01;
+}

src/ec/purism/librem-ec/librem_ec.h

@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef LIBREM_EC_H
+#define LIBREM_EC_H
+
+#include <stdbool.h>
+
+/*
+ * Check whether librem-ec has working jack detect.  This was fixed in librem-ec
+ * 1.13, so we only use the verbs with jack detect if the EC has been updated.
+ */
+bool librem_ec_has_jack_detect(void);
+
+#endif

src/ec/system76/ec/system76_ec.c

@@ -1,7 +1,9 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
+#include "system76_ec.h"
 #include <arch/io.h>
 #include <console/system76_ec.h>
+#include <console/console.h>
 #include <timer.h>
 
 // This is the command region for System76 EC firmware. It must be
@@ -11,10 +13,13 @@
 
 #define REG_CMD 0
 #define REG_RESULT 1
+#define REG_DATA 2	// Start of command data
 
 // When command register is 0, command is complete
 #define CMD_FINISHED 0
 
+#define RESULT_OK 0
+
 // Print command. Registers are unique for each command
 #define CMD_PRINT 4
 #define CMD_PRINT_REG_FLAGS 2
@@ -59,3 +64,49 @@ void system76_ec_print(uint8_t byte)
 	if (byte == '\n' || len >= (SYSTEM76_EC_SIZE - CMD_PRINT_REG_DATA))
 		system76_ec_flush();
 }
+
+bool system76_ec_cmd(uint8_t cmd, const uint8_t *request_data,
+	uint8_t request_size, uint8_t *reply_data, uint8_t reply_size)
+{
+	if (request_size > SYSTEM76_EC_SIZE - REG_DATA ||
+		reply_size > SYSTEM76_EC_SIZE - REG_DATA) {
+		printk(BIOS_ERR, "EC command %d too long - request size %u, reply size %u\n",
+			cmd, request_size, reply_size);
+		return false;
+	}
+
+	/* If any data were buffered by system76_ec_print(), flush it first */
+	uint8_t buffered_len = system76_ec_read(CMD_PRINT_REG_LEN);
+	if (buffered_len > 0)
+		system76_ec_flush();
+
+	/* Write the data */
+	uint8_t i;
+	for (i = 0; i < request_size; ++i)
+		system76_ec_write(REG_DATA + i, request_data[i]);
+
+	/* Write the command */
+	system76_ec_write(REG_CMD, cmd);
+
+	/* Wait for the command to complete */
+	bool ret = true;
+	int elapsed = wait_ms(1000, system76_ec_read(REG_CMD) == CMD_FINISHED);
+	if (elapsed == 0) {
+		/* Timed out: fail the command, don't attempt to read a reply. */
+		printk(BIOS_WARNING, "EC command %d timed out - request size %d, reply size %d\n",
+			cmd, request_size, reply_size);
+		ret = false;
+	} else {
+		/* Read the reply */
+		for (i = 0; i < reply_size; ++i)
+			reply_data[i] = system76_ec_read(REG_DATA+i);
+		/* Check the reply status */
+		ret = (system76_ec_read(REG_RESULT) == RESULT_OK);
+	}
+
+	/* Reset the flags and length so we can buffer console prints again */
+	system76_ec_write(CMD_PRINT_REG_FLAGS, 0);
+	system76_ec_write(CMD_PRINT_REG_LEN, 0);
+
+	return ret;
+}

src/ec/system76/ec/system76_ec.h

@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef SYSTEM76_EC_H
+#define SYSTEM76_EC_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/*
+ * Send a command to the EC.  request_data/request_size are the request payload,
+ * request_data can be NULL if request_size is 0.  reply_data/reply_size are
+ * the reply payload, reply_data can be NULL if reply_size is 0.
+ */
+bool system76_ec_cmd(uint8_t cmd, const uint8_t *request_data,
+	uint8_t request_size, uint8_t *reply_data, uint8_t reply_size);
+
+#endif