cros_ec.c

/*
 * Chromium OS cros_ec driver
 *
 * Copyright (c) 2012 The Chromium OS Authors.
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

/*
 * This is the interface to the Chrome OS EC. It provides keyboard functions,
 * power control and battery management. Quite a few other functions are
 * provided to enable the EC software to be updated, talk to the EC's I2C bus
 * and store a small amount of data in a memory which persists while the EC
 * is not reset.
 */

#include <common.h>
#include <command.h>
#include <dm.h>
#include <i2c.h>
#include <cros_ec.h>
#include <fdtdec.h>
#include <malloc.h>
#include <spi.h>
#include <linux/errno.h>
#include <asm/io.h>
#include <asm-generic/gpio.h>
#include <dm/device-internal.h>
#include <dm/uclass-internal.h>

#ifdef DEBUG_TRACE
#define debug_trace(fmt, b...)	debug(fmt, #b)
#else
#define debug_trace(fmt, b...)
#endif

enum {
	/* Timeout waiting for a flash erase command to complete */
	CROS_EC_CMD_TIMEOUT_MS	= 5000,
	/* Timeout waiting for a synchronous hash to be recomputed */
	CROS_EC_CMD_HASH_TIMEOUT_MS = 2000,
};

DECLARE_GLOBAL_DATA_PTR;

void cros_ec_dump_data(const char *name, int cmd, const uint8_t *data, int len)
{
#ifdef DEBUG
	int i;

	printf("%s: ", name);
	if (cmd != -1)
		printf("cmd=%#x: ", cmd);
	for (i = 0; i < len; i++)
		printf("%02x ", data[i]);
	printf("\n");
#endif
}

/*
 * Calculate a simple 8-bit checksum of a data block
 *
 * @param data	Data block to checksum
 * @param size	Size of data block in bytes
 * @return checksum value (0 to 255)
 */
int cros_ec_calc_checksum(const uint8_t *data, int size)
{
	int csum, i;

	for (i = csum = 0; i < size; i++)
		csum += data[i];
	return csum & 0xff;
}

/**
 * Create a request packet for protocol version 3.
 *
 * The packet is stored in the device's internal output buffer.
 *
 * @param dev		CROS-EC device
 * @param cmd		Command to send (EC_CMD_...)
 * @param cmd_version	Version of command to send (EC_VER_...)
 * @param dout          Output data (may be NULL If dout_len=0)
 * @param dout_len      Size of output data in bytes
 * @return packet size in bytes, or <0 if error.
 */
static int create_proto3_request(struct cros_ec_dev *dev,
				 int cmd, int cmd_version,
				 const void *dout, int dout_len)
{
	struct ec_host_request *rq = (struct ec_host_request *)dev->dout;
	int out_bytes = dout_len + sizeof(*rq);

	/* Fail if output size is too big */
	if (out_bytes > (int)sizeof(dev->dout)) {
		debug("%s: Cannot send %d bytes\n", __func__, dout_len);
		return -EC_RES_REQUEST_TRUNCATED;
	}

	/* Fill in request packet */
	rq->struct_version = EC_HOST_REQUEST_VERSION;
	rq->checksum = 0;
	rq->command = cmd;
	rq->command_version = cmd_version;
	rq->reserved = 0;
	rq->data_len = dout_len;

	/* Copy data after header */
	memcpy(rq + 1, dout, dout_len);

	/* Write checksum field so the entire packet sums to 0 */
	rq->checksum = (uint8_t)(-cros_ec_calc_checksum(dev->dout, out_bytes));

	cros_ec_dump_data("out", cmd, dev->dout, out_bytes);

	/* Return size of request packet */
	return out_bytes;
}

/**
 * Prepare the device to receive a protocol version 3 response.
 *
 * @param dev		CROS-EC device
 * @param din_len       Maximum size of response in bytes
 * @return maximum expected number of bytes in response, or <0 if error.
 */
static int prepare_proto3_response_buffer(struct cros_ec_dev *dev, int din_len)
{
	int in_bytes = din_len + sizeof(struct ec_host_response);

	/* Fail if input size is too big */
	if (in_bytes > (int)sizeof(dev->din)) {
		debug("%s: Cannot receive %d bytes\n", __func__, din_len);
		return -EC_RES_RESPONSE_TOO_BIG;
	}

	/* Return expected size of response packet */
	return in_bytes;
}

/**
 * Handle a protocol version 3 response packet.
 *
 * The packet must already be stored in the device's internal input buffer.
 *
 * @param dev		CROS-EC device
 * @param dinp          Returns pointer to response data
 * @param din_len       Maximum size of response in bytes
 * @return number of bytes of response data, or <0 if error. Note that error
 * codes can be from errno.h or -ve EC_RES_INVALID_CHECKSUM values (and they
 * overlap!)
 */
static int handle_proto3_response(struct cros_ec_dev *dev,
				  uint8_t **dinp, int din_len)
{
	struct ec_host_response *rs = (struct ec_host_response *)dev->din;
	int in_bytes;
	int csum;

	cros_ec_dump_data("in-header", -1, dev->din, sizeof(*rs));

	/* Check input data */
	if (rs->struct_version != EC_HOST_RESPONSE_VERSION) {
		debug("%s: EC response version mismatch\n", __func__);
		return -EC_RES_INVALID_RESPONSE;
	}

	if (rs->reserved) {
		debug("%s: EC response reserved != 0\n", __func__);
		return -EC_RES_INVALID_RESPONSE;
	}

	if (rs->data_len > din_len) {
		debug("%s: EC returned too much data\n", __func__);
		return -EC_RES_RESPONSE_TOO_BIG;
	}

	cros_ec_dump_data("in-data", -1, dev->din + sizeof(*rs), rs->data_len);

	/* Update in_bytes to actual data size */
	in_bytes = sizeof(*rs) + rs->data_len;

	/* Verify checksum */
	csum = cros_ec_calc_checksum(dev->din, in_bytes);
	if (csum) {
		debug("%s: EC response checksum invalid: 0x%02x\n", __func__,
		      csum);
		return -EC_RES_INVALID_CHECKSUM;
	}

	/* Return error result, if any */
	if (rs->result)
		return -(int)rs->result;

	/* If we're still here, set response data pointer and return length */
	*dinp = (uint8_t *)(rs + 1);

	return rs->data_len;
}