text: // SPDX-License-Identifier: GPL-2.0+
  /*
   * Chromium OS cros_ec driver - I2C interface
   *
   * Copyright (c) 2012 The Chromium OS Authors.
   */
  
  /*
   * The Matrix Keyboard Protocol driver handles talking to the keyboard
   * controller chip. Mostly this is for keyboard functions, but some other
   * things have slipped in, so we provide generic services to talk to the
   * KBC.
   */
  
  #include <common.h>
  #include <dm.h>
  #include <i2c.h>
  #include <cros_ec.h>
  
  #ifdef DEBUG_TRACE
  #define debug_trace(fmt, b...)	debug(fmt, #b)
  #else
  #define debug_trace(fmt, b...)
  #endif
  
  /**
   * Request format for protocol v3
   * byte 0	0xda (EC_COMMAND_PROTOCOL_3)
   * byte 1-8	struct ec_host_request
   * byte 10-	response data
   */
  struct ec_host_request_i2c {
  	/* Always 0xda to backward compatible with v2 struct */
  	uint8_t  command_protocol;
  	struct ec_host_request ec_request;
  } __packed;
  
  /*
   * Response format for protocol v3
   * byte 0	result code
   * byte 1	packet_length
   * byte 2-9	struct ec_host_response
   * byte 10-	response data
   */
  struct ec_host_response_i2c {
  	uint8_t result;
  	uint8_t packet_length;
  	struct ec_host_response ec_response;
  } __packed;
  
  static int cros_ec_i2c_packet(struct udevice *udev, int out_bytes, int in_bytes)
  {
  	struct cros_ec_dev *dev = dev_get_uclass_priv(udev);
  	struct dm_i2c_chip *chip = dev_get_parent_platdata(udev);
  	struct ec_host_request_i2c *ec_request_i2c =
  		(struct ec_host_request_i2c *)dev->dout;
  	struct ec_host_response_i2c *ec_response_i2c =
  		(struct ec_host_response_i2c *)dev->din;
  	struct i2c_msg i2c_msg[2];
  	int ret;
  
  	i2c_msg[0].addr = chip->chip_addr;
  	i2c_msg[0].flags = 0;
  	i2c_msg[1].addr = chip->chip_addr;
  	i2c_msg[1].flags = I2C_M_RD;
  
  	/* one extra byte, to indicate v3 */
  	i2c_msg[0].len = out_bytes + 1;
  	i2c_msg[0].buf = dev->dout;
  
  	/* stitch on EC_COMMAND_PROTOCOL_3 */
  	memmove(&ec_request_i2c->ec_request, dev->dout, out_bytes);
  	ec_request_i2c->command_protocol = EC_COMMAND_PROTOCOL_3;
  
  	/* two extra bytes for v3 */
  	i2c_msg[1].len = in_bytes + 2;
  	i2c_msg[1].buf = dev->din;
  
  	ret = dm_i2c_xfer(udev, &i2c_msg[0], 2);
  	if (ret) {
  		printf("%s: Could not execute transfer: %d\n", __func__, ret);
  		return ret;
  	}
  
  	/* When we send a v3 request to v2 ec, ec won't recognize the 0xda
  	 * (EC_COMMAND_PROTOCOL_3) and will return with status
  	 * EC_RES_INVALID_COMMAND with zero data length
  	 *
  	 * In case of invalid command for v3 protocol the data length
  	 * will be at least sizeof(struct ec_host_response)
  	 */
  	if (ec_response_i2c->result == EC_RES_INVALID_COMMAND &&
  	    ec_response_i2c->packet_length == 0)
  		return -EPROTONOSUPPORT;
  
  	if (ec_response_i2c->packet_length < sizeof(struct ec_host_response)) {
  		printf("%s: response of %u bytes too short; not a full hdr\n",
  		       __func__, ec_response_i2c->packet_length);
  		return -EBADMSG;
  	}
  
  
  	/* drop result and packet_len */
  	memmove(dev->din, &ec_response_i2c->ec_response, in_bytes);
  
  	return in_bytes;
  }
  
  static int cros_ec_i2c_command(struct udevice *udev, uint8_t cmd,
  			       int cmd_version, const uint8_t *dout,
  			       int dout_len, uint8_t **dinp, int din_len)
  {
  	struct cros_ec_dev *dev = dev_get_uclass_priv(udev);
  	struct dm_i2c_chip *chip = dev_get_parent_platdata(udev);
  	struct i2c_msg i2c_msg[2];
  	/* version8, cmd8, arglen8, out8[dout_len], csum8 */
  	int out_bytes = dout_len + 4;
  	/* response8, arglen8, in8[din_len], checksum8 */
  	int in_bytes = din_len + 3;
  	uint8_t *ptr;
  	/* Receive input data, so that args will be dword aligned */
  	uint8_t *in_ptr;
  	int len, csum, ret;
  
  	/*
  	 * Sanity-check I/O sizes given transaction overhead in internal
  	 * buffers.
  	 */
  	if (out_bytes > sizeof(dev->dout)) {
  		debug("%s: Cannot send %d bytes\n", __func__, dout_len);
  		return -1;
  	}
  	if (in_bytes > sizeof(dev->din)) {
  		debug("%s: Cannot receive %d bytes\n", __func__, din_len);
  		return -1;
  	}
  	assert(dout_len >= 0);
  	assert(dinp);
  
  	i2c_msg[0].addr = chip->chip_addr;
  	i2c_msg[0].len = out_bytes;
  	i2c_msg[0].buf = dev->dout;
  	i2c_msg[0].flags = 0;
  
  	/*
  	 * Copy command and data into output buffer so we can do a single I2C
  	 * burst transaction.
  	 */
  	ptr = dev->dout;
  
  	/*
  	 * in_ptr starts of pointing to a dword-aligned input data buffer.
  	 * We decrement it back by the number of header bytes we expect to
  	 * receive, so that the first parameter of the resulting input data
  	 * will be dword aligned.
  	 */
  	in_ptr = dev->din + sizeof(int64_t);
  
  	if (dev->protocol_version != 2) {
  		/* Something we don't support */
  		debug("%s: Protocol version %d unsupported\n",
  		      __func__, dev->protocol_version);
  		return -1;
  	}
  
  	*ptr++ = EC_CMD_VERSION0 + cmd_version;
  	*ptr++ = cmd;
  	*ptr++ = dout_len;
  	in_ptr -= 2;	/* Expect status, length bytes */
  
  	memcpy(ptr, dout, dout_len);
  	ptr += dout_len;
  
  	*ptr++ = (uint8_t)
  		cros_ec_calc_checksum(dev->dout, dout_len + 3);
  
  	i2c_msg[1].addr = chip->chip_addr;
  	i2c_msg[1].len = in_bytes;
  	i2c_msg[1].buf = in_ptr;
  	i2c_msg[1].flags = I2C_M_RD;
  
  	/* Send output data */
  	cros_ec_dump_data("out", -1, dev->dout, out_bytes);
  
  	ret = dm_i2c_xfer(udev, &i2c_msg[0], 2);
  	if (ret) {
  		debug("%s: Could not execute transfer to %s\n", __func__,
  		      udev->name);
  		ret = -1;
  	}
  
  	if (*in_ptr != EC_RES_SUCCESS) {
  		debug("%s: Received bad result code %d\n", __func__, *in_ptr);
  		return -(int)*in_ptr;
  	}
  
  	len = in_ptr[1];
  	if (len + 3 > sizeof(dev->din)) {
  		debug("%s: Received length %#02x too large\n",
  		      __func__, len);
  		return -1;
  	}
  	csum = cros_ec_calc_checksum(in_ptr, 2 + len);
  	if (csum != in_ptr[2 + len]) {
  		debug("%s: Invalid checksum rx %#02x, calced %#02x\n",
  		      __func__, in_ptr[2 + din_len], csum);
  		return -1;
  	}
  	din_len = min(din_len, len);
  	cros_ec_dump_data("in", -1, in_ptr, din_len + 3);
  
  	/* Return pointer to dword-aligned input data, if any */
  	*dinp = dev->din + sizeof(int64_t);
  
  	return din_len;
  }
  
  static int cros_ec_probe(struct udevice *dev)
  {
  	return cros_ec_register(dev);
  }
  
  static struct dm_cros_ec_ops cros_ec_ops = {
  	.command = cros_ec_i2c_command,
  	.packet = cros_ec_i2c_packet,
  };
  
  static const struct udevice_id cros_ec_ids[] = {
  	{ .compatible = "google,cros-ec-i2c" },
  	{ }
  };
  
  U_BOOT_DRIVER(cros_ec_i2c) = {
  	.name		= "cros_ec_i2c",
  	.id		= UCLASS_CROS_EC,
  	.of_match	= cros_ec_ids,
  	.probe		= cros_ec_probe,
  	.ops		= &cros_ec_ops,
  };
  