Date:	Mon, 15 Jun 2015 13:24:23 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>,
	Olof Johansson <olof@...om.net>,
	Doug Anderson <dianders@...omium.org>,
	Bill Richardson <wfrichar@...omium.org>,
	Simon Glass <sjg@...gle.com>,
	Gwendal Grignou <gwendal@...gle.com>,
	Stephen Barber <smbarber@...omium.org>,
	Filipe Brandenburger <filbranden@...gle.com>,
	Todd Broch <tbroch@...omium.org>,
	Alexandru M Stan <amstan@...omium.org>,
	Heiko Stuebner <heiko@...ech.de>,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v7 5/8] mfd: cros_ec: add bus-specific proto v3 code

On Tue, 09 Jun 2015, Javier Martinez Canillas wrote:

> From: Stephen Barber <smbarber@...omium.org>
> 
> Add proto v3 support to the SPI, I2C, and LPC.
> 
> Signed-off-by: Stephen Barber <smbarber@...omium.org>
> Signed-off-by: Javier Martinez Canillas <javier.martinez@...labora.co.uk>
> Tested-by: Heiko Stuebner <heiko@...ech.de>
> Reviewed-by: Gwendal Grignou <gwendal@...omium.org>
> Tested-by: Gwendal Grignou <gwendal@...omium.org>
> Acked-by: Lee Jones <lee.jones@...aro.org>
> Acked-by: Olof Johansson <olof@...om.net>

Applied, thanks.

> ---
> 
> Changes since v6:
>  - Add Olof Johansson Acked-by tag
> 
> Changes since v5: None
> 
> Changes since v4: None
> 
> Changes since v3:
>  - Added acked-by tag from Lee Jones.
> 
> Changes since v2: None
> 
> Changes since v1:
>  - Added Gwendal Grignou Reviewed-by and Tested-by tags
> ---
>  drivers/mfd/cros_ec_i2c.c             | 166 ++++++++++++++-
>  drivers/mfd/cros_ec_spi.c             | 382 +++++++++++++++++++++++++++++-----
>  drivers/platform/chrome/cros_ec_lpc.c |  73 ++++++-
>  include/linux/mfd/cros_ec.h           |   6 +
>  4 files changed, 569 insertions(+), 58 deletions(-)
> 
> diff --git a/drivers/mfd/cros_ec_i2c.c b/drivers/mfd/cros_ec_i2c.c
> index b400bfa2772a..22e8a4ae1711 100644
> --- a/drivers/mfd/cros_ec_i2c.c
> +++ b/drivers/mfd/cros_ec_i2c.c
> @@ -13,6 +13,7 @@
>   * GNU General Public License for more details.
>   */
>  
> +#include <linux/delay.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/i2c.h>
> @@ -22,6 +23,32 @@
>  #include <linux/platform_device.h>
>  #include <linux/slab.h>
>  
> +/**
> + * 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 inline struct cros_ec_device *to_ec_dev(struct device *dev)
>  {
>  	struct i2c_client *client = to_i2c_client(dev);
> @@ -29,6 +56,134 @@ static inline struct cros_ec_device *to_ec_dev(struct device *dev)
>  	return i2c_get_clientdata(client);
>  }
>  
> +static int cros_ec_pkt_xfer_i2c(struct cros_ec_device *ec_dev,
> +				struct cros_ec_command *msg)
> +{
> +	struct i2c_client *client = ec_dev->priv;
> +	int ret = -ENOMEM;
> +	int i;
> +	int packet_len;
> +	u8 *out_buf = NULL;
> +	u8 *in_buf = NULL;
> +	u8 sum;
> +	struct i2c_msg i2c_msg[2];
> +	struct ec_host_response *ec_response;
> +	struct ec_host_request_i2c *ec_request_i2c;
> +	struct ec_host_response_i2c *ec_response_i2c;
> +	int request_header_size = sizeof(struct ec_host_request_i2c);
> +	int response_header_size = sizeof(struct ec_host_response_i2c);
> +
> +	i2c_msg[0].addr = client->addr;
> +	i2c_msg[0].flags = 0;
> +	i2c_msg[1].addr = client->addr;
> +	i2c_msg[1].flags = I2C_M_RD;
> +
> +	packet_len = msg->insize + response_header_size;
> +	BUG_ON(packet_len > ec_dev->din_size);
> +	in_buf = ec_dev->din;
> +	i2c_msg[1].len = packet_len;
> +	i2c_msg[1].buf = (char *) in_buf;
> +
> +	packet_len = msg->outsize + request_header_size;
> +	BUG_ON(packet_len > ec_dev->dout_size);
> +	out_buf = ec_dev->dout;
> +	i2c_msg[0].len = packet_len;
> +	i2c_msg[0].buf = (char *) out_buf;
> +
> +	/* create request data */
> +	ec_request_i2c = (struct ec_host_request_i2c *) out_buf;
> +	ec_request_i2c->command_protocol = EC_COMMAND_PROTOCOL_3;
> +
> +	ec_dev->dout++;
> +	ret = cros_ec_prepare_tx(ec_dev, msg);
> +	ec_dev->dout--;
> +
> +	/* send command to EC and read answer */
> +	ret = i2c_transfer(client->adapter, i2c_msg, 2);
> +	if (ret < 0) {
> +		dev_dbg(ec_dev->dev, "i2c transfer failed: %d\n", ret);
> +		goto done;
> +	} else if (ret != 2) {
> +		dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
> +		ret = -EIO;
> +		goto done;
> +	}
> +
> +	ec_response_i2c = (struct ec_host_response_i2c *) in_buf;
> +	msg->result = ec_response_i2c->result;
> +	ec_response = &ec_response_i2c->ec_response;
> +
> +	switch (msg->result) {
> +	case EC_RES_SUCCESS:
> +		break;
> +	case EC_RES_IN_PROGRESS:
> +		ret = -EAGAIN;
> +		dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
> +			msg->command);
> +		goto done;
> +
> +	default:
> +		dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
> +			msg->command, msg->result);
> +		/*
> +		 * When we send 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) {
> +			ret = -EPROTONOSUPPORT;
> +			goto done;
> +		}
> +	}
> +
> +	if (ec_response_i2c->packet_length < sizeof(struct ec_host_response)) {
> +		dev_err(ec_dev->dev,
> +			"response of %u bytes too short; not a full header\n",
> +			ec_response_i2c->packet_length);
> +		ret = -EBADMSG;
> +		goto done;
> +	}
> +
> +	if (msg->insize < ec_response->data_len) {
> +		dev_err(ec_dev->dev,
> +			"response data size is too large: expected %u, got %u\n",
> +			msg->insize,
> +			ec_response->data_len);
> +		ret = -EMSGSIZE;
> +		goto done;
> +	}
> +
> +	/* copy response packet payload and compute checksum */
> +	sum = 0;
> +	for (i = 0; i < sizeof(struct ec_host_response); i++)
> +		sum += ((u8 *)ec_response)[i];
> +
> +	memcpy(msg->data,
> +	       in_buf + response_header_size,
> +	       ec_response->data_len);
> +	for (i = 0; i < ec_response->data_len; i++)
> +		sum += msg->data[i];
> +
> +	/* All bytes should sum to zero */
> +	if (sum) {
> +		dev_err(ec_dev->dev, "bad packet checksum\n");
> +		ret = -EBADMSG;
> +		goto done;
> +	}
> +
> +	ret = ec_response->data_len;
> +
> +done:
> +	if (msg->command == EC_CMD_REBOOT_EC)
> +		msleep(EC_REBOOT_DELAY_MS);
> +
> +	return ret;
> +}
> +
>  static int cros_ec_cmd_xfer_i2c(struct cros_ec_device *ec_dev,
>  				struct cros_ec_command *msg)
>  {
> @@ -121,9 +276,12 @@ static int cros_ec_cmd_xfer_i2c(struct cros_ec_device *ec_dev,
>  	}
>  
>  	ret = len;
> - done:
> +done:
>  	kfree(in_buf);
>  	kfree(out_buf);
> +	if (msg->command == EC_CMD_REBOOT_EC)
> +		msleep(EC_REBOOT_DELAY_MS);
> +
>  	return ret;
>  }
>  
> @@ -143,12 +301,12 @@ static int cros_ec_i2c_probe(struct i2c_client *client,
>  	ec_dev->priv = client;
>  	ec_dev->irq = client->irq;
>  	ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
> -	ec_dev->pkt_xfer = NULL;
> +	ec_dev->pkt_xfer = cros_ec_pkt_xfer_i2c;
>  	ec_dev->ec_name = client->name;
>  	ec_dev->phys_name = client->adapter->name;
> -	ec_dev->din_size = sizeof(struct ec_host_response) +
> +	ec_dev->din_size = sizeof(struct ec_host_response_i2c) +
>  			   sizeof(struct ec_response_get_protocol_info);
> -	ec_dev->dout_size = sizeof(struct ec_host_request);
> +	ec_dev->dout_size = sizeof(struct ec_host_request_i2c);
>  
>  	err = cros_ec_register(ec_dev);
>  	if (err) {
> diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c
> index 04da2f288ef8..4e6f2f6b1095 100644
> --- a/drivers/mfd/cros_ec_spi.c
> +++ b/drivers/mfd/cros_ec_spi.c
> @@ -65,12 +65,6 @@
>    */
>  #define EC_SPI_RECOVERY_TIME_NS	(200 * 1000)
>  
> -/*
> - * The EC is unresponsive for a time after a reboot command.  Add a
> - * simple delay to make sure that the bus stays locked.
> - */
> -#define EC_REBOOT_DELAY_MS	50
> -
>  /**
>   * struct cros_ec_spi - information about a SPI-connected EC
>   *
> @@ -87,7 +81,7 @@ struct cros_ec_spi {
>  };
>  
>  static void debug_packet(struct device *dev, const char *name, u8 *ptr,
> -			  int len)
> +			 int len)
>  {
>  #ifdef DEBUG
>  	int i;
> @@ -100,6 +94,172 @@ static void debug_packet(struct device *dev, const char *name, u8 *ptr,
>  #endif
>  }
>  
> +static int terminate_request(struct cros_ec_device *ec_dev)
> +{
> +	struct cros_ec_spi *ec_spi = ec_dev->priv;
> +	struct spi_message msg;
> +	struct spi_transfer trans;
> +	int ret;
> +
> +	/*
> +	 * Turn off CS, possibly adding a delay to ensure the rising edge
> +	 * doesn't come too soon after the end of the data.
> +	 */
> +	spi_message_init(&msg);
> +	memset(&trans, 0, sizeof(trans));
> +	trans.delay_usecs = ec_spi->end_of_msg_delay;
> +	spi_message_add_tail(&trans, &msg);
> +
> +	ret = spi_sync(ec_spi->spi, &msg);
> +
> +	/* Reset end-of-response timer */
> +	ec_spi->last_transfer_ns = ktime_get_ns();
> +	if (ret < 0) {
> +		dev_err(ec_dev->dev,
> +			"cs-deassert spi transfer failed: %d\n",
> +			ret);
> +	}
> +
> +	return ret;
> +}
> +
> +/**
> + * receive_n_bytes - receive n bytes from the EC.
> + *
> + * Assumes buf is a pointer into the ec_dev->din buffer
> + */
> +static int receive_n_bytes(struct cros_ec_device *ec_dev, u8 *buf, int n)
> +{
> +	struct cros_ec_spi *ec_spi = ec_dev->priv;
> +	struct spi_transfer trans;
> +	struct spi_message msg;
> +	int ret;
> +
> +	BUG_ON(buf - ec_dev->din + n > ec_dev->din_size);
> +
> +	memset(&trans, 0, sizeof(trans));
> +	trans.cs_change = 1;
> +	trans.rx_buf = buf;
> +	trans.len = n;
> +
> +	spi_message_init(&msg);
> +	spi_message_add_tail(&trans, &msg);
> +	ret = spi_sync(ec_spi->spi, &msg);
> +	if (ret < 0)
> +		dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
> +
> +	return ret;
> +}
> +
> +/**
> + * cros_ec_spi_receive_packet - Receive a packet from the EC.
> + *
> + * This function has two phases: reading the preamble bytes (since if we read
> + * data from the EC before it is ready to send, we just get preamble) and
> + * reading the actual message.
> + *
> + * The received data is placed into ec_dev->din.
> + *
> + * @ec_dev: ChromeOS EC device
> + * @need_len: Number of message bytes we need to read
> + */
> +static int cros_ec_spi_receive_packet(struct cros_ec_device *ec_dev,
> +				      int need_len)
> +{
> +	struct ec_host_response *response;
> +	u8 *ptr, *end;
> +	int ret;
> +	unsigned long deadline;
> +	int todo;
> +
> +	BUG_ON(EC_MSG_PREAMBLE_COUNT > ec_dev->din_size);
> +
> +	/* Receive data until we see the header byte */
> +	deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS);
> +	while (true) {
> +		unsigned long start_jiffies = jiffies;
> +
> +		ret = receive_n_bytes(ec_dev,
> +				      ec_dev->din,
> +				      EC_MSG_PREAMBLE_COUNT);
> +		if (ret < 0)
> +			return ret;
> +
> +		ptr = ec_dev->din;
> +		for (end = ptr + EC_MSG_PREAMBLE_COUNT; ptr != end; ptr++) {
> +			if (*ptr == EC_SPI_FRAME_START) {
> +				dev_dbg(ec_dev->dev, "msg found at %zd\n",
> +					ptr - ec_dev->din);
> +				break;
> +			}
> +		}
> +		if (ptr != end)
> +			break;
> +
> +		/*
> +		 * Use the time at the start of the loop as a timeout.  This
> +		 * gives us one last shot at getting the transfer and is useful
> +		 * in case we got context switched out for a while.
> +		 */
> +		if (time_after(start_jiffies, deadline)) {
> +			dev_warn(ec_dev->dev, "EC failed to respond in time\n");
> +			return -ETIMEDOUT;
> +		}
> +	}
> +
> +	/*
> +	 * ptr now points to the header byte. Copy any valid data to the
> +	 * start of our buffer
> +	 */
> +	todo = end - ++ptr;
> +	BUG_ON(todo < 0 || todo > ec_dev->din_size);
> +	todo = min(todo, need_len);
> +	memmove(ec_dev->din, ptr, todo);
> +	ptr = ec_dev->din + todo;
> +	dev_dbg(ec_dev->dev, "need %d, got %d bytes from preamble\n",
> +		need_len, todo);
> +	need_len -= todo;
> +
> +	/* If the entire response struct wasn't read, get the rest of it. */
> +	if (todo < sizeof(*response)) {
> +		ret = receive_n_bytes(ec_dev, ptr, sizeof(*response) - todo);
> +		if (ret < 0)
> +			return -EBADMSG;
> +		ptr += (sizeof(*response) - todo);
> +		todo = sizeof(*response);
> +	}
> +
> +	response = (struct ec_host_response *)ec_dev->din;
> +
> +	/* Abort if data_len is too large. */
> +	if (response->data_len > ec_dev->din_size)
> +		return -EMSGSIZE;
> +
> +	/* Receive data until we have it all */
> +	while (need_len > 0) {
> +		/*
> +		 * We can't support transfers larger than the SPI FIFO size
> +		 * unless we have DMA. We don't have DMA on the ISP SPI ports
> +		 * for Exynos. We need a way of asking SPI driver for
> +		 * maximum-supported transfer size.
> +		 */
> +		todo = min(need_len, 256);
> +		dev_dbg(ec_dev->dev, "loop, todo=%d, need_len=%d, ptr=%zd\n",
> +			todo, need_len, ptr - ec_dev->din);
> +
> +		ret = receive_n_bytes(ec_dev, ptr, todo);
> +		if (ret < 0)
> +			return ret;
> +
> +		ptr += todo;
> +		need_len -= todo;
> +	}
> +
> +	dev_dbg(ec_dev->dev, "loop done, ptr=%zd\n", ptr - ec_dev->din);
> +
> +	return 0;
> +}
> +
>  /**
>   * cros_ec_spi_receive_response - Receive a response from the EC.
>   *
> @@ -115,34 +275,27 @@ static void debug_packet(struct device *dev, const char *name, u8 *ptr,
>  static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev,
>  					int need_len)
>  {
> -	struct cros_ec_spi *ec_spi = ec_dev->priv;
> -	struct spi_transfer trans;
> -	struct spi_message msg;
>  	u8 *ptr, *end;
>  	int ret;
>  	unsigned long deadline;
>  	int todo;
>  
> +	BUG_ON(EC_MSG_PREAMBLE_COUNT > ec_dev->din_size);
> +
>  	/* Receive data until we see the header byte */
>  	deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS);
>  	while (true) {
>  		unsigned long start_jiffies = jiffies;
>  
> -		memset(&trans, 0, sizeof(trans));
> -		trans.cs_change = 1;
> -		trans.rx_buf = ptr = ec_dev->din;
> -		trans.len = EC_MSG_PREAMBLE_COUNT;
> -
> -		spi_message_init(&msg);
> -		spi_message_add_tail(&trans, &msg);
> -		ret = spi_sync(ec_spi->spi, &msg);
> -		if (ret < 0) {
> -			dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
> +		ret = receive_n_bytes(ec_dev,
> +				      ec_dev->din,
> +				      EC_MSG_PREAMBLE_COUNT);
> +		if (ret < 0)
>  			return ret;
> -		}
>  
> +		ptr = ec_dev->din;
>  		for (end = ptr + EC_MSG_PREAMBLE_COUNT; ptr != end; ptr++) {
> -			if (*ptr == EC_MSG_HEADER) {
> +			if (*ptr == EC_SPI_FRAME_START) {
>  				dev_dbg(ec_dev->dev, "msg found at %zd\n",
>  					ptr - ec_dev->din);
>  				break;
> @@ -187,21 +340,9 @@ static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev,
>  		dev_dbg(ec_dev->dev, "loop, todo=%d, need_len=%d, ptr=%zd\n",
>  			todo, need_len, ptr - ec_dev->din);
>  
> -		memset(&trans, 0, sizeof(trans));
> -		trans.cs_change = 1;
> -		trans.rx_buf = ptr;
> -		trans.len = todo;
> -		spi_message_init(&msg);
> -		spi_message_add_tail(&trans, &msg);
> -
> -		/* send command to EC and read answer */
> -		BUG_ON((u8 *)trans.rx_buf - ec_dev->din + todo >
> -				ec_dev->din_size);
> -		ret = spi_sync(ec_spi->spi, &msg);
> -		if (ret < 0) {
> -			dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
> +		ret = receive_n_bytes(ec_dev, ptr, todo);
> +		if (ret < 0)
>  			return ret;
> -		}
>  
>  		debug_packet(ec_dev->dev, "interim", ptr, todo);
>  		ptr += todo;
> @@ -214,6 +355,128 @@ static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev,
>  }
>  
>  /**
> + * cros_ec_pkt_xfer_spi - Transfer a packet over SPI and receive the reply
> + *
> + * @ec_dev: ChromeOS EC device
> + * @ec_msg: Message to transfer
> + */
> +static int cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev,
> +				struct cros_ec_command *ec_msg)
> +{
> +	struct ec_host_request *request;
> +	struct ec_host_response *response;
> +	struct cros_ec_spi *ec_spi = ec_dev->priv;
> +	struct spi_transfer trans;
> +	struct spi_message msg;
> +	int i, len;
> +	u8 *ptr;
> +	u8 *rx_buf;
> +	u8 sum;
> +	int ret = 0, final_ret;
> +
> +	len = cros_ec_prepare_tx(ec_dev, ec_msg);
> +	request = (struct ec_host_request *)ec_dev->dout;
> +	dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
> +
> +	/* If it's too soon to do another transaction, wait */
> +	if (ec_spi->last_transfer_ns) {
> +		unsigned long delay;	/* The delay completed so far */
> +
> +		delay = ktime_get_ns() - ec_spi->last_transfer_ns;
> +		if (delay < EC_SPI_RECOVERY_TIME_NS)
> +			ndelay(EC_SPI_RECOVERY_TIME_NS - delay);
> +	}
> +
> +	rx_buf = kzalloc(len, GFP_KERNEL);
> +	if (!rx_buf) {
> +		ret = -ENOMEM;
> +		goto exit;
> +	}
> +
> +	/* Transmit phase - send our message */
> +	memset(&trans, 0, sizeof(trans));
> +	trans.tx_buf = ec_dev->dout;
> +	trans.rx_buf = rx_buf;
> +	trans.len = len;
> +	trans.cs_change = 1;
> +	spi_message_init(&msg);
> +	spi_message_add_tail(&trans, &msg);
> +	ret = spi_sync(ec_spi->spi, &msg);
> +
> +	/* Get the response */
> +	if (!ret) {
> +		/* Verify that EC can process command */
> +		for (i = 0; i < len; i++) {
> +			switch (rx_buf[i]) {
> +			case EC_SPI_PAST_END:
> +			case EC_SPI_RX_BAD_DATA:
> +			case EC_SPI_NOT_READY:
> +				ret = -EAGAIN;
> +				ec_msg->result = EC_RES_IN_PROGRESS;
> +			default:
> +				break;
> +			}
> +			if (ret)
> +				break;
> +		}
> +		if (!ret)
> +			ret = cros_ec_spi_receive_packet(ec_dev,
> +					ec_msg->insize + sizeof(*response));
> +	} else {
> +		dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
> +	}
> +
> +	final_ret = terminate_request(ec_dev);
> +	if (!ret)
> +		ret = final_ret;
> +	if (ret < 0)
> +		goto exit;
> +
> +	ptr = ec_dev->din;
> +
> +	/* check response error code */
> +	response = (struct ec_host_response *)ptr;
> +	ec_msg->result = response->result;
> +
> +	ret = cros_ec_check_result(ec_dev, ec_msg);
> +	if (ret)
> +		goto exit;
> +
> +	len = response->data_len;
> +	sum = 0;
> +	if (len > ec_msg->insize) {
> +		dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
> +			len, ec_msg->insize);
> +		ret = -EMSGSIZE;
> +		goto exit;
> +	}
> +
> +	for (i = 0; i < sizeof(*response); i++)
> +		sum += ptr[i];
> +
> +	/* copy response packet payload and compute checksum */
> +	memcpy(ec_msg->data, ptr + sizeof(*response), len);
> +	for (i = 0; i < len; i++)
> +		sum += ec_msg->data[i];
> +
> +	if (sum) {
> +		dev_err(ec_dev->dev,
> +			"bad packet checksum, calculated %x\n",
> +			sum);
> +		ret = -EBADMSG;
> +		goto exit;
> +	}
> +
> +	ret = len;
> +exit:
> +	kfree(rx_buf);
> +	if (ec_msg->command == EC_CMD_REBOOT_EC)
> +		msleep(EC_REBOOT_DELAY_MS);
> +
> +	return ret;
> +}
> +
> +/**
>   * cros_ec_cmd_xfer_spi - Transfer a message over SPI and receive the reply
>   *
>   * @ec_dev: ChromeOS EC device
> @@ -227,6 +490,7 @@ static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
>  	struct spi_message msg;
>  	int i, len;
>  	u8 *ptr;
> +	u8 *rx_buf;
>  	int sum;
>  	int ret = 0, final_ret;
>  
> @@ -242,10 +506,17 @@ static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
>  			ndelay(EC_SPI_RECOVERY_TIME_NS - delay);
>  	}
>  
> +	rx_buf = kzalloc(len, GFP_KERNEL);
> +	if (!rx_buf) {
> +		ret = -ENOMEM;
> +		goto exit;
> +	}
> +
>  	/* Transmit phase - send our message */
>  	debug_packet(ec_dev->dev, "out", ec_dev->dout, len);
>  	memset(&trans, 0, sizeof(trans));
>  	trans.tx_buf = ec_dev->dout;
> +	trans.rx_buf = rx_buf;
>  	trans.len = len;
>  	trans.cs_change = 1;
>  	spi_message_init(&msg);
> @@ -254,29 +525,32 @@ static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
>  
>  	/* Get the response */
>  	if (!ret) {
> -		ret = cros_ec_spi_receive_response(ec_dev,
> -				ec_msg->insize + EC_MSG_TX_PROTO_BYTES);
> +		/* Verify that EC can process command */
> +		for (i = 0; i < len; i++) {
> +			switch (rx_buf[i]) {
> +			case EC_SPI_PAST_END:
> +			case EC_SPI_RX_BAD_DATA:
> +			case EC_SPI_NOT_READY:
> +				ret = -EAGAIN;
> +				ec_msg->result = EC_RES_IN_PROGRESS;
> +			default:
> +				break;
> +			}
> +			if (ret)
> +				break;
> +		}
> +		if (!ret)
> +			ret = cros_ec_spi_receive_response(ec_dev,
> +					ec_msg->insize + EC_MSG_TX_PROTO_BYTES);
>  	} else {
>  		dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
>  	}
>  
> -	/*
> -	 * Turn off CS, possibly adding a delay to ensure the rising edge
> -	 * doesn't come too soon after the end of the data.
> -	 */
> -	spi_message_init(&msg);
> -	memset(&trans, 0, sizeof(trans));
> -	trans.delay_usecs = ec_spi->end_of_msg_delay;
> -	spi_message_add_tail(&trans, &msg);
> -
> -	final_ret = spi_sync(ec_spi->spi, &msg);
> -	ec_spi->last_transfer_ns = ktime_get_ns();
> +	final_ret = terminate_request(ec_dev);
>  	if (!ret)
>  		ret = final_ret;
> -	if (ret < 0) {
> -		dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
> +	if (ret < 0)
>  		goto exit;
> -	}
>  
>  	ptr = ec_dev->din;
>  
> @@ -315,6 +589,7 @@ static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
>  
>  	ret = len;
>  exit:
> +	kfree(rx_buf);
>  	if (ec_msg->command == EC_CMD_REBOOT_EC)
>  		msleep(EC_REBOOT_DELAY_MS);
>  
> @@ -361,7 +636,7 @@ static int cros_ec_spi_probe(struct spi_device *spi)
>  	ec_dev->priv = ec_spi;
>  	ec_dev->irq = spi->irq;
>  	ec_dev->cmd_xfer = cros_ec_cmd_xfer_spi;
> -	ec_dev->pkt_xfer = NULL;
> +	ec_dev->pkt_xfer = cros_ec_pkt_xfer_spi;
>  	ec_dev->ec_name = ec_spi->spi->modalias;
>  	ec_dev->phys_name = dev_name(&ec_spi->spi->dev);
>  	ec_dev->din_size = EC_MSG_PREAMBLE_COUNT +
> @@ -369,6 +644,7 @@ static int cros_ec_spi_probe(struct spi_device *spi)
>  			   sizeof(struct ec_response_get_protocol_info);
>  	ec_dev->dout_size = sizeof(struct ec_host_request);
>  
> +
>  	err = cros_ec_register(ec_dev);
>  	if (err) {
>  		dev_err(dev, "cannot register EC\n");
> diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
> index 06c5790b2c28..92b633324aaa 100644
> --- a/drivers/platform/chrome/cros_ec_lpc.c
> +++ b/drivers/platform/chrome/cros_ec_lpc.c
> @@ -46,6 +46,77 @@ static int ec_response_timed_out(void)
>  	return 1;
>  }
>  
> +static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
> +				struct cros_ec_command *msg)
> +{
> +	struct ec_host_request *request;
> +	struct ec_host_response response;
> +	u8 sum = 0;
> +	int i;
> +	int ret = 0;
> +	u8 *dout;
> +
> +	ret = cros_ec_prepare_tx(ec, msg);
> +
> +	/* Write buffer */
> +	for (i = 0; i < ret; i++)
> +		outb(ec->dout[i], EC_LPC_ADDR_HOST_PACKET + i);
> +
> +	request = (struct ec_host_request *)ec->dout;
> +
> +	/* Here we go */
> +	outb(EC_COMMAND_PROTOCOL_3, EC_LPC_ADDR_HOST_CMD);
> +
> +	if (ec_response_timed_out()) {
> +		dev_warn(ec->dev, "EC responsed timed out\n");
> +		ret = -EIO;
> +		goto done;
> +	}
> +
> +	/* Check result */
> +	msg->result = inb(EC_LPC_ADDR_HOST_DATA);
> +	ret = cros_ec_check_result(ec, msg);
> +	if (ret)
> +		goto done;
> +
> +	/* Read back response */
> +	dout = (u8 *)&response;
> +	for (i = 0; i < sizeof(response); i++) {
> +		dout[i] = inb(EC_LPC_ADDR_HOST_PACKET + i);
> +		sum += dout[i];
> +	}
> +
> +	msg->result = response.result;
> +
> +	if (response.data_len > msg->insize) {
> +		dev_err(ec->dev,
> +			"packet too long (%d bytes, expected %d)",
> +			response.data_len, msg->insize);
> +		ret = -EMSGSIZE;
> +		goto done;
> +	}
> +
> +	/* Read response and process checksum */
> +	for (i = 0; i < response.data_len; i++) {
> +		msg->data[i] =
> +			inb(EC_LPC_ADDR_HOST_PACKET + sizeof(response) + i);
> +		sum += msg->data[i];
> +	}
> +
> +	if (sum) {
> +		dev_err(ec->dev,
> +			"bad packet checksum %02x\n",
> +			response.checksum);
> +		ret = -EBADMSG;
> +		goto done;
> +	}
> +
> +	/* Return actual amount of data received */
> +	ret = response.data_len;
> +done:
> +	return ret;
> +}
> +
>  static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
>  				struct cros_ec_command *msg)
>  {
> @@ -205,7 +276,7 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
>  	ec_dev->ec_name = pdev->name;
>  	ec_dev->phys_name = dev_name(dev);
>  	ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
> -	ec_dev->pkt_xfer = NULL;
> +	ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
>  	ec_dev->cmd_readmem = cros_ec_lpc_readmem;
>  	ec_dev->din_size = sizeof(struct ec_host_response) +
>  			   sizeof(struct ec_response_get_protocol_info);
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index 59d909434efd..92e13aaa450c 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -22,6 +22,12 @@
>  #include <linux/mutex.h>
>  
>  /*
> + * The EC is unresponsive for a time after a reboot command.  Add a
> + * simple delay to make sure that the bus stays locked.
> + */
> +#define EC_REBOOT_DELAY_MS             50
> +
> +/*
>   * Max bus-specific overhead incurred by request/responses.
>   * I2C requires 1 additional byte for requests.
>   * I2C requires 2 additional bytes for responses.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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