Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH v3] platform: chrome: Add ChromeOS EC ISHTP driver
To:     Rushikesh S Kadam <rushikesh.s.kadam@intel.com>,
        srinivas.pandruvada@linux.intel.com, bleung@chromium.org,
        groeck@chromium.org
Cc:     ncrews@chromium.org, jettrink@chromium.org, gwendal@google.com,
        linux-kernel@vger.kernel.org
References: <1554639014-28363-1-git-send-email-rushikesh.s.kadam@intel.com>
From:   Enric Balletbo i Serra <enric.balletbo@collabora.com>
Message-ID: <00733542-3094-3cf0-7d6f-d2ba34a805da@collabora.com>
Date:   Mon, 15 Apr 2019 17:24:00 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.6.1
MIME-Version: 1.0
In-Reply-To: <1554639014-28363-1-git-send-email-rushikesh.s.kadam@intel.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-GB
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Rushikesh,

Just few style comments and this can go throught the hid tree.

On 7/4/19 14:10, Rushikesh S Kadam wrote:
> This driver implements a slim layer to enable the ChromeOS
> EC kernel stack (cros_ec) to communicate with ChromeOS EC
> firmware running on the Intel Integrated Sensor Hub (ISH).
> 
> The driver registers a ChromeOS EC MFD device to connect
> with cros_ec kernel stack (upper layer), and it registers a
> client with the ISH Transport Protocol bus (lower layer) to
> talk with the ISH firwmare. See description of the ISHTP
> protocol at Documentation/hid/intel-ish-hid.txt
> 
> Signed-off-by: Rushikesh S Kadam <rushikesh.s.kadam@intel.com>
> ---
> 
> v3
>  - Made several changes to improve code readability. Replaced
>    multiple cl_data_to_dev(client_data) with dev variable. Use
>    reverse Xmas tree for variable defintion where it made sense.
>    Dropped few debug prints. Add docstring for function
>    prepare_cros_ec_rx().
>  - Fix code in function prepare_cros_ec_rx() under label
>    end_cros_ec_dev_init_error.
>  - Recycle buffer in process_recv() on failing to obtain the
>    semaphore.
>  - Increase ISHTP TX/RX ring buffer size to 8.
>  - Alphabetically ordered CROS_EC_ISHTP entries in Makefile and
>    Kconfig.
>  - Updated commit message.
> 
> v2
>  - Dropped unused "reset" parameter in function cros_ec_init()
>  - Change driver name to cros_ec_ishtp to be consistent with other
>    references in the code.
>  - Fixed a few typos. 
> 
> v1
>  - Initial version
> 
>  drivers/platform/chrome/Kconfig         |  13 +
>  drivers/platform/chrome/Makefile        |   1 +
>  drivers/platform/chrome/cros_ec_ishtp.c | 765 ++++++++++++++++++++++++++++++++
>  3 files changed, 779 insertions(+)
>  create mode 100644 drivers/platform/chrome/cros_ec_ishtp.c
> 
> diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> index 16b1615..5848179 100644
> --- a/drivers/platform/chrome/Kconfig
> +++ b/drivers/platform/chrome/Kconfig
> @@ -62,6 +62,19 @@ config CROS_EC_I2C
>  	  a checksum. Failing accesses will be retried three times to
>  	  improve reliability.
>  
> +config CROS_EC_ISHTP
> +	tristate "ChromeOS Embedded Controller (ISHTP)"
> +	depends on MFD_CROS_EC
> +	depends on INTEL_ISH_HID
> +	help
> +	  If you say Y here, you get support for talking to the ChromeOS EC
> +	  firmware running on Intel Integrated Sensor Hub (ISH), using the
> +	  ISH Transport protocol (ISH-TP). This uses a simple byte-level
> +	  protocol with a checksum.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called cros_ec_ishtp.
> +
>  config CROS_EC_SPI
>  	tristate "ChromeOS Embedded Controller (SPI)"
>  	depends on MFD_CROS_EC && SPI
> diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> index cd591bf..4efe102 100644
> --- a/drivers/platform/chrome/Makefile
> +++ b/drivers/platform/chrome/Makefile
> @@ -7,6 +7,7 @@ cros_ec_ctl-objs			:= cros_ec_sysfs.o cros_ec_lightbar.o \
>  					   cros_ec_vbc.o cros_ec_debugfs.o
>  obj-$(CONFIG_CROS_EC_CTL)		+= cros_ec_ctl.o
>  obj-$(CONFIG_CROS_EC_I2C)		+= cros_ec_i2c.o
> +obj-$(CONFIG_CROS_EC_ISHTP)		+= cros_ec_ishtp.o
>  obj-$(CONFIG_CROS_EC_SPI)		+= cros_ec_spi.o
>  cros_ec_lpcs-objs			:= cros_ec_lpc.o cros_ec_lpc_reg.o
>  cros_ec_lpcs-$(CONFIG_CROS_EC_LPC_MEC)	+= cros_ec_lpc_mec.o
> diff --git a/drivers/platform/chrome/cros_ec_ishtp.c b/drivers/platform/chrome/cros_ec_ishtp.c
> new file mode 100644
> index 0000000..b1d19c4
> --- /dev/null
> +++ b/drivers/platform/chrome/cros_ec_ishtp.c
> @@ -0,0 +1,765 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * ISHTP client driver for talking to the Chrome OS EC firmware running
> + * on Intel Integrated Sensor Hub (ISH) using the ISH Transport protocol
> + * (ISH-TP).
> + *
> + * Copyright (c) 2019, Intel Corporation.
> + */
> +

To be coherent with the other cros_ec_* files, please use the c++ style as follows

// SPDX-License-Identifier: GPL-2.0
// ISHTP interface for ChromeOS Embedded Controller
//
// Copyright (c) 2019, Intel Corporation.
//
// ISHTP client driver for talking to the Chrome OS EC firmware running
// on Intel Integrated Sensor Hub (ISH) using the ISH Transport protocol
// (ISH-TP).


> +#include <linux/delay.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/cros_ec.h>
> +#include <linux/mfd/cros_ec_commands.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/intel-ish-client-if.h>
> +
> +/*
> + * ISH TX/RX ring buffer pool size
> + *
> + * The AP->ISH messages and corresponding ISH->AP responses are
> + * serialized. We need 1 TX and 1 RX buffer for these.
> + *
> + * The MKBP ISH->AP events are serialized. We need one additional RX
> + * buffer for them.
> + */
> +#define CROS_ISH_CL_TX_RING_SIZE		8
> +#define CROS_ISH_CL_RX_RING_SIZE		8
> +
> +/* ISH CrOS EC Host Commands */
> +enum cros_ec_ish_channel {
> +	CROS_EC_COMMAND = 1,			/* AP->ISH message */
> +	CROS_MKBP_EVENT = 2,			/* ISH->AP events */
> +};
> +
> +/*
> + * ISH firmware timeout for 1 message send failure is 1Hz, and the
> + * firmware will retry 2 times, so 3Hz is used for timeout.
> + */
> +#define ISHTP_SEND_TIMEOUT			(3 * HZ)
> +
> +/* ISH Transport CrOS EC ISH client unique GUID */
> +static const guid_t cros_ish_guid =
> +	GUID_INIT(0x7b7154d0, 0x56f4, 0x4bdc,
> +		  0xb0, 0xd8, 0x9e, 0x7c, 0xda,	0xe0, 0xd6, 0xa0);
> +
> +struct header {
> +	u8 channel;
> +	u8 status;
> +	u8 reserved[2];
> +} __packed;
> +
> +struct cros_ish_out_msg {
> +	struct header hdr;
> +	struct ec_host_request ec_request;
> +} __packed;
> +
> +struct cros_ish_in_msg {
> +	struct header hdr;
> +	struct ec_host_response ec_response;
> +} __packed;
> +
> +#define IN_MSG_EC_RESPONSE_PREAMBLE					\
> +	offsetof(struct cros_ish_in_msg, ec_response)
> +
> +#define OUT_MSG_EC_REQUEST_PREAMBLE					\
> +	offsetof(struct cros_ish_out_msg, ec_request)
> +
> +#define cl_data_to_dev(client_data) ishtp_device((client_data)->cl_device)
> +
> +/*
> + * The Read-Write Semaphore is used to prevent message TX or RX while
> + * the ishtp client is being initialized or undergoing reset.
> + *
> + * The readers are the kernel function calls responsible for IA->ISH
> + * and ISH->AP messaging.
> + *
> + * The writers are .reset() and .probe() function.
> + */
> +DECLARE_RWSEM(init_lock);
> +
> +/**
> + * struct response_info - Encapsulate firmware response related
> + *			information for passing between function
> + *			ish_send() and process_recv() callback.
> + * @data:		Copy the data received from firmware here.

For all documentation use just one space instead of tabs

@data: Copy ...

> + * @max_size:		Max size allocated for the @data buffer. If the

So we don't have these weirds alignments

@max_size: Max ...

> + *			received data exceeds this value, we log an
> + *			error.
> + * @size:		Actual size of data received from firmware.
> + * @error:		0 for success, negative error code for a
> + *			failure in function process_recv().
> + * @received:		Set to true on receiving a valid firmware
> + *			response to host command
> + * @wait_queue:		Wait queue for Host firmware loading where the
> + *			client sends message to ISH firmware and waits
> + *			for response
> + */
> +struct response_info {
> +	void *data;
> +	size_t max_size;
> +	size_t size;
> +	int error;
> +	bool received;
> +	wait_queue_head_t wait_queue;
> +};
> +
> +/**
> + * struct ishtp_cl_data - Encapsulate per ISH TP Client.
> + * @cros_ish_cl:	ISHTP firmware client instance.
> + * @cl_device:		ISHTP client device instance.
> + * @response:		Firmware response information for passing
> + *			between function ish_send() and process_recv()
> + *			callback.
> + * @work_ishtp_reset:	Work queue reset handling.
> + * @work_ec_evt:	Work queue for EC events.
> + * @ec_dev:		CrOS EC MFD device.
> + *
> + * This structure is used to store per client data.
> + */
> +struct ishtp_cl_data {
> +	struct ishtp_cl *cros_ish_cl;
> +	struct ishtp_cl_device *cl_device;
> +
> +	/*
> +	 * Used for passing firmware response information between
> +	 * ish_send() and process_recv() callback.
> +	 */
> +	struct response_info response;
> +
> +	struct work_struct work_ishtp_reset;
> +	struct work_struct work_ec_evt;
> +	struct cros_ec_device *ec_dev;
> +};
> +
> +/**
> + * ish_evt_handler - ISH to AP event handler
> + * @work:		Work struct
> + */
> +static void ish_evt_handler(struct work_struct *work)
> +{
> +	struct ishtp_cl_data *client_data =
> +		container_of(work, struct ishtp_cl_data, work_ec_evt);
> +	struct cros_ec_device *ec_dev = client_data->ec_dev;
> +
> +	if (cros_ec_get_next_event(ec_dev, NULL) > 0) {
> +		blocking_notifier_call_chain(&ec_dev->event_notifier,
> +					     0, ec_dev);
> +	}
> +}
> +
> +/**
> + * ish_send() - Send message from host to firmware
> + * @client_data:	Client data instance
> + * @out_msg:		Message buffer to be sent to firmware
> + * @out_size:		Size of out going message
> + * @in_msg:		Message buffer where the incoming data copied.
> + *			This buffer is allocated by calling
> + * @in_size:		Max size of incoming message
> + *
> + * Return: Number of bytes copied in the in_msg on success, negative
> + * error code on failure.
> + */
> +static int ish_send(struct ishtp_cl_data *client_data,
> +		    u8 *out_msg, size_t out_size,
> +		    u8 *in_msg, size_t in_size)
> +{
> +	int rv;
> +	struct header *out_hdr = (struct header *)out_msg;
> +	struct ishtp_cl *cros_ish_cl = client_data->cros_ish_cl;
> +
> +	dev_dbg(cl_data_to_dev(client_data),
> +		"%s: channel=%02u status=%02u\n",
> +		__func__, out_hdr->channel, out_hdr->status);
> +
> +	/* Setup for incoming response */
> +	client_data->response.data = in_msg;
> +	client_data->response.max_size = in_size;
> +	client_data->response.error = 0;
> +	client_data->response.received = false;
> +
> +	rv = ishtp_cl_send(cros_ish_cl, out_msg, out_size);
> +	if (rv) {
> +		dev_err(cl_data_to_dev(client_data),
> +			"ishtp_cl_send error %d\n", rv);
> +		return rv;
> +	}
> +
> +	wait_event_interruptible_timeout(client_data->response.wait_queue,
> +					 client_data->response.received,
> +					 ISHTP_SEND_TIMEOUT);
> +	if (!client_data->response.received) {
> +		dev_err(cl_data_to_dev(client_data),
> +			"Timed out for response to host message\n");
> +		return -ETIMEDOUT;
> +	}
> +
> +	if (client_data->response.error < 0)
> +		return client_data->response.error;
> +
> +	return client_data->response.size;
> +}
> +
> +/**
> + * process_recv() -	Received and parse incoming packet
> + * @cros_ish_cl:	Client instance to get stats
> + * @rb_in_proc:		Host interface message buffer
> + *
> + * Parse the incoming packet. If it is a response packet then it will
> + * update per instance flags and wake up the caller waiting to for the
> + * response. If it is an event packet then it will schedule event work.
> + */
> +static void process_recv(struct ishtp_cl *cros_ish_cl,
> +			 struct ishtp_cl_rb *rb_in_proc)
> +{
> +	size_t data_len = rb_in_proc->buf_idx;
> +	struct ishtp_cl_data *client_data =
> +		ishtp_get_client_data(cros_ish_cl);
> +	struct device *dev = cl_data_to_dev(client_data);
> +	struct cros_ish_in_msg *in_msg =
> +		(struct cros_ish_in_msg *)rb_in_proc->buffer.data;
> +
> +	/* Proceed only if reset or init is not in progress */
> +	if (!down_read_trylock(&init_lock)) {
> +		/* Free the buffer */
> +		ishtp_cl_io_rb_recycle(rb_in_proc);
> +		dev_warn(dev,
> +			 "Host is not ready to receive incoming messages\n");
> +		return;
> +	}
> +
> +	/*
> +	 * All firmware messages contain a header. Check the buffer size
> +	 * before accessing elements inside.
> +	 */
> +	if (!rb_in_proc->buffer.data) {
> +		dev_warn(dev, "rb_in_proc->buffer.data returned null");
> +		client_data->response.error = -EBADMSG;
> +		goto end_error;
> +	}
> +
> +	if (data_len < sizeof(struct header)) {
> +		dev_err(dev, "data size %zu is less than header %zu\n",
> +			data_len, sizeof(struct header));
> +		client_data->response.error = -EMSGSIZE;
> +		goto end_error;
> +	}
> +
> +	dev_dbg(dev, "channel=%02u status=%02u\n",
> +		in_msg->hdr.channel, in_msg->hdr.status);
> +
> +	switch (in_msg->hdr.channel) {
> +	case CROS_EC_COMMAND:
> +		/* Sanity check */
> +		if (!client_data->response.data) {
> +			dev_err(dev,
> +				"Receiving buffer is null. Should be allocated by calling function\n");
> +			client_data->response.error = -EINVAL;
> +			goto error_wake_up;
> +		}
> +
> +		if (client_data->response.received) {
> +			dev_err(dev,
> +				"Previous firmware message not yet processed\n");
> +			client_data->response.error = -EINVAL;
> +			goto error_wake_up;
> +		}
> +
> +		if (data_len > client_data->response.max_size) {
> +			dev_err(dev,
> +				"Received buffer size %zu is larger than allocated buffer %zu\n",
> +				data_len, client_data->response.max_size);
> +			client_data->response.error = -EMSGSIZE;
> +			goto error_wake_up;
> +		}
> +
> +		if (in_msg->hdr.status) {
> +			dev_err(dev, "firmware returned status %d\n",
> +				in_msg->hdr.status);
> +			client_data->response.error = -EIO;
> +			goto error_wake_up;
> +		}
> +
> +		/* Update the actual received buffer size */
> +		client_data->response.size = data_len;
> +
> +		/*
> +		 * Copy the buffer received in firmware response for the
> +		 * calling thread.
> +		 */
> +		memcpy(client_data->response.data,
> +		       rb_in_proc->buffer.data, data_len);
> +
> +		/* Set flag before waking up the caller */
> +		client_data->response.received = true;
> +error_wake_up:
> +		/* Wake the calling thread */
> +		wake_up_interruptible(&client_data->response.wait_queue);
> +
> +		break;
> +
> +	case CROS_MKBP_EVENT:
> +		/* The event system doesn't send any data in buffer */
> +		schedule_work(&client_data->work_ec_evt);
> +
> +		break;
> +
> +	default:
> +		dev_err(dev, "Invalid channel=%02d\n", in_msg->hdr.channel);
> +	}
> +
> +end_error:
> +	/* Free the buffer */
> +	ishtp_cl_io_rb_recycle(rb_in_proc);
> +
> +	up_read(&init_lock);
> +}
> +
> +/**
> + * ish_event_cb() - bus driver callback for incoming message
> + * @cl_device:		ISHTP client device for which this message is
> + *			targeted.
> + *
> + * Remove the packet from the list and process the message by calling
> + * process_recv.
> + */
> +static void ish_event_cb(struct ishtp_cl_device *cl_device)
> +{
> +	struct ishtp_cl_rb *rb_in_proc;
> +	struct ishtp_cl	*cros_ish_cl = ishtp_get_drvdata(cl_device);
> +
> +	while ((rb_in_proc = ishtp_cl_rx_get_rb(cros_ish_cl)) != NULL) {
> +		/* Decide what to do with received data */
> +		process_recv(cros_ish_cl, rb_in_proc);
> +	}
> +}
> +
> +/**
> + * cros_ish_init() - Init function for ISHTP client
> + * @cros_ish_cl:	ISHTP client instance
> + *
> + * This function complete the initializtion of the client.
> + *
> + * Return: 0 for success, negative error code for failure.
> + */
> +static int cros_ish_init(struct ishtp_cl *cros_ish_cl)
> +{
> +	int rv;
> +	struct ishtp_device *dev;
> +	struct ishtp_fw_client *fw_client;
> +	struct ishtp_cl_data *client_data = ishtp_get_client_data(cros_ish_cl);
> +
> +	rv = ishtp_cl_link(cros_ish_cl);
> +	if (rv) {
> +		dev_err(cl_data_to_dev(client_data),
> +			"ishtp_cl_link failed\n");
> +		return rv;
> +	}
> +
> +	dev = ishtp_get_ishtp_device(cros_ish_cl);
> +
> +	/* Connect to firmware client */
> +	ishtp_set_tx_ring_size(cros_ish_cl, CROS_ISH_CL_TX_RING_SIZE);
> +	ishtp_set_rx_ring_size(cros_ish_cl, CROS_ISH_CL_RX_RING_SIZE);
> +
> +	fw_client = ishtp_fw_cl_get_client(dev, &cros_ish_guid);
> +	if (!fw_client) {
> +		dev_err(cl_data_to_dev(client_data),
> +			"ish client uuid not found\n");
> +		rv = -ENOENT;
> +		goto err_cl_unlink;
> +	}
> +
> +	ishtp_cl_set_fw_client_id(cros_ish_cl,
> +				  ishtp_get_fw_client_id(fw_client));
> +	ishtp_set_connection_state(cros_ish_cl, ISHTP_CL_CONNECTING);
> +
> +	rv = ishtp_cl_connect(cros_ish_cl);
> +	if (rv) {
> +		dev_err(cl_data_to_dev(client_data),
> +			"client connect fail\n");
> +		goto err_cl_unlink;
> +	}
> +
> +	ishtp_register_event_cb(client_data->cl_device, ish_event_cb);
> +	return 0;
> +
> +err_cl_unlink:
> +	ishtp_cl_unlink(cros_ish_cl);
> +	return rv;
> +}
> +
> +/**
> + * cros_ish_deinit() - Deinit function for ISHTP client
> + * @cros_ish_cl:	ISHTP client instance
> + *
> + * Unlink and free cros_ec client
> + */
> +static void cros_ish_deinit(struct ishtp_cl *cros_ish_cl)
> +{
> +	ishtp_set_connection_state(cros_ish_cl, ISHTP_CL_DISCONNECTING);
> +	ishtp_cl_disconnect(cros_ish_cl);
> +	ishtp_cl_unlink(cros_ish_cl);
> +	ishtp_cl_flush_queues(cros_ish_cl);
> +
> +	/* Disband and free all Tx and Rx client-level rings */
> +	ishtp_cl_free(cros_ish_cl);
> +}
> +
> +/**
> + * prepare_cros_ec_rx() - Check & prepare receive buffer

Missing @ec_dev

> + * @in_msg:		Incoming message buffer
> + * @cros_ec_command	cros_ec command used to send & receive data

s/cros_ec_command/msg:/

> + *
> + * Check the received buffer. Convert to cros_ec_command format.

Missing description for return value.

> + */
> +static int prepare_cros_ec_rx(struct cros_ec_device *ec_dev,
> +			      const struct cros_ish_in_msg *in_msg,
> +			      struct cros_ec_command *msg)
> +{
> +	u8 sum = 0;
> +	int i, rv, offset;

nit: Here and in all the code I prefer Reverse X-mas tree when possible, thanks

int i, rv, offset;
u8 sum = 0;

> +
> +	/* Check response error code */
> +	msg->result = in_msg->ec_response.result;
> +	rv = cros_ec_check_result(ec_dev, msg);
> +	if (rv < 0)
> +		return rv;
> +
> +	if (in_msg->ec_response.data_len > msg->insize) {
> +		dev_err(ec_dev->dev, "Packet too long (%d bytes, expected %d)",
> +			in_msg->ec_response.data_len, msg->insize);
> +		return -ENOSPC;
> +	}
> +
> +	/* Copy response packet payload and compute checksum */
> +	for (i = 0; i < sizeof(struct ec_host_response); i++)
> +		sum += ((u8 *)in_msg)[IN_MSG_EC_RESPONSE_PREAMBLE + i];
> +
> +	offset = sizeof(struct cros_ish_in_msg);
> +	for (i = 0; i < in_msg->ec_response.data_len; i++)
> +		sum += msg->data[i] = ((u8 *)in_msg)[offset + i];
> +
> +	if (sum) {
> +		dev_dbg(ec_dev->dev, "Bad received packet checksum %d\n", sum);
> +		return -EBADMSG;
> +	}
> +
> +	return 0;
> +}
> +
> +static int cros_ec_pkt_xfer_ish(struct cros_ec_device *ec_dev,
> +				struct cros_ec_command *msg)
> +{
> +	int rv;
> +	struct ishtp_cl *cros_ish_cl = ec_dev->priv;
> +	struct ishtp_cl_data *client_data = ishtp_get_client_data(cros_ish_cl);
> +	struct device *dev = cl_data_to_dev(client_data);
> +	struct cros_ish_in_msg *in_msg = (struct cros_ish_in_msg *)ec_dev->din;
> +	struct cros_ish_out_msg *out_msg =
> +		(struct cros_ish_out_msg *)ec_dev->dout;
> +	size_t in_size = sizeof(struct cros_ish_in_msg) + msg->insize;
> +	size_t out_size = sizeof(struct cros_ish_out_msg) + msg->outsize;
> +
> +	/* Proceed only if reset-init is not in progress */
> +	if (!down_read_trylock(&init_lock)) {
> +		dev_warn(dev,
> +			 "Host is not ready to send messages to ISH. Try again\n");
> +		return -EAGAIN;
> +	}
> +
> +	/* Sanity checks */
> +	if (in_size > ec_dev->din_size) {
> +		dev_err(dev,
> +			"Incoming payload size %zu is too large for ec_dev->din_size %d\n",
> +			in_size, ec_dev->din_size);
> +		return -EMSGSIZE;
> +	}
> +
> +	if (out_size > ec_dev->dout_size) {
> +		dev_err(dev,
> +			"Outgoing payload size %zu is too large for ec_dev->dout_size %d\n",
> +			out_size, ec_dev->dout_size);
> +		return -EMSGSIZE;
> +	}
> +
> +	/* Prepare the package to be sent over ISH TP */
> +	out_msg->hdr.channel = CROS_EC_COMMAND;
> +	out_msg->hdr.status = 0;
> +
> +	ec_dev->dout += OUT_MSG_EC_REQUEST_PREAMBLE;
> +	cros_ec_prepare_tx(ec_dev, msg);
> +	ec_dev->dout -= OUT_MSG_EC_REQUEST_PREAMBLE;
> +
> +	dev_dbg(dev,
> +		"out_msg: struct_ver=0x%x checksum=0x%x command=0x%x command_ver=0x%x data_len=0x%x\n",
> +		out_msg->ec_request.struct_version,
> +		out_msg->ec_request.checksum,
> +		out_msg->ec_request.command,
> +		out_msg->ec_request.command_version,
> +		out_msg->ec_request.data_len);
> +
> +	/* Send command to ISH EC firmware and read response */
> +	rv = ish_send(client_data,
> +		      (u8 *)out_msg, out_size,
> +		      (u8 *)in_msg, in_size);
> +	if (rv < 0)
> +		goto end_error;
> +
> +	rv = prepare_cros_ec_rx(ec_dev, in_msg, msg);
> +	if (rv)
> +		goto end_error;
> +
> +	rv = in_msg->ec_response.data_len;
> +
> +	dev_dbg(dev,
> +		"in_msg: struct_ver=0x%x checksum=0x%x result=0x%x data_len=0x%x\n",
> +		in_msg->ec_response.struct_version,
> +		in_msg->ec_response.checksum,
> +		in_msg->ec_response.result,
> +		in_msg->ec_response.data_len);
> +
> +end_error:
> +	if (msg->command == EC_CMD_REBOOT_EC)
> +		msleep(EC_REBOOT_DELAY_MS);
> +
> +	up_read(&init_lock);
> +
> +	return rv;
> +}
> +
> +static int cros_ec_dev_init(struct ishtp_cl_data *client_data)
> +{
> +	struct cros_ec_device *ec_dev;
> +	struct device *dev = cl_data_to_dev(client_data);
> +
> +	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
> +	if (!ec_dev)
> +		return -ENOMEM;
> +
> +	client_data->ec_dev = ec_dev;
> +	dev->driver_data = ec_dev;
> +
> +	ec_dev->dev = dev;
> +	ec_dev->priv = client_data->cros_ish_cl;
> +	ec_dev->cmd_xfer = NULL;
> +	ec_dev->pkt_xfer = cros_ec_pkt_xfer_ish;
> +	ec_dev->phys_name = dev_name(dev);
> +	ec_dev->din_size = sizeof(struct cros_ish_in_msg) +
> +			   sizeof(struct ec_response_get_protocol_info);
> +	ec_dev->dout_size = sizeof(struct cros_ish_out_msg);
> +
> +	return cros_ec_register(ec_dev);
> +}
> +
> +static void reset_handler(struct work_struct *work)
> +{
> +	int rv;
> +	struct device *dev;
> +	struct ishtp_cl *cros_ish_cl;
> +	struct ishtp_cl_device *cl_device;
> +	struct ishtp_cl_data *client_data =
> +		container_of(work, struct ishtp_cl_data, work_ishtp_reset);
> +
> +	/* Lock for reset to complete */
> +	down_write(&init_lock);
> +
> +	cros_ish_cl = client_data->cros_ish_cl;
> +	cl_device = client_data->cl_device;
> +
> +	/* Unlink, flush queues & start again */
> +	ishtp_cl_unlink(cros_ish_cl);
> +	ishtp_cl_flush_queues(cros_ish_cl);
> +	ishtp_cl_free(cros_ish_cl);
> +
> +	cros_ish_cl = ishtp_cl_allocate(cl_device);
> +	if (!cros_ish_cl) {
> +		up_write(&init_lock);
> +		return;
> +	}
> +
> +	ishtp_set_drvdata(cl_device, cros_ish_cl);
> +	ishtp_set_client_data(cros_ish_cl, client_data);
> +	client_data->cros_ish_cl = cros_ish_cl;
> +
> +	rv = cros_ish_init(cros_ish_cl);
> +	if (rv) {
> +		ishtp_cl_free(cros_ish_cl);
> +		dev_err(cl_data_to_dev(client_data), "Reset Failed\n");
> +		up_write(&init_lock);
> +		return;
> +	}
> +
> +	/* Refresh ec_dev device pointers */
> +	client_data->ec_dev->priv = client_data->cros_ish_cl;
> +	dev = cl_data_to_dev(client_data);
> +	dev->driver_data = client_data->ec_dev;
> +
> +	dev_info(cl_data_to_dev(client_data), "Chrome EC ISH reset done\n");
> +
> +	up_write(&init_lock);
> +}
> +
> +/**
> + * cros_ec_ishtp_probe() - ISHTP client driver probe callback
> + * @cl_device:		ISHTP client device instance
> + *
> + * Return: 0 for success, negative error code for failure.
> + */
> +static int cros_ec_ishtp_probe(struct ishtp_cl_device *cl_device)
> +{
> +	int rv;
> +	struct ishtp_cl *cros_ish_cl;
> +	struct ishtp_cl_data *client_data =
> +		devm_kzalloc(ishtp_device(cl_device),
> +			     sizeof(*client_data), GFP_KERNEL);
> +	if (!client_data)
> +		return -ENOMEM;
> +
> +	/* Lock for initialization to complete */
> +	down_write(&init_lock);
> +
> +	cros_ish_cl = ishtp_cl_allocate(cl_device);
> +	if (!cros_ish_cl) {
> +		rv = -ENOMEM;
> +		goto end_ishtp_cl_alloc_error;
> +	}
> +
> +	ishtp_set_drvdata(cl_device, cros_ish_cl);
> +	ishtp_set_client_data(cros_ish_cl, client_data);
> +	client_data->cros_ish_cl = cros_ish_cl;
> +	client_data->cl_device = cl_device;
> +
> +	init_waitqueue_head(&client_data->response.wait_queue);
> +
> +	INIT_WORK(&client_data->work_ishtp_reset,
> +		  reset_handler);
> +	INIT_WORK(&client_data->work_ec_evt,
> +		  ish_evt_handler);
> +
> +	rv = cros_ish_init(cros_ish_cl);
> +	if (rv)
> +		goto end_ishtp_cl_init_error;
> +
> +	ishtp_get_device(cl_device);
> +
> +	up_write(&init_lock);
> +
> +	/* Register croc_ec_dev mfd */
> +	rv = cros_ec_dev_init(client_data);
> +	if (rv)
> +		goto end_cros_ec_dev_init_error;
> +
> +	return 0;
> +
> +end_cros_ec_dev_init_error:
> +	ishtp_set_connection_state(cros_ish_cl, ISHTP_CL_DISCONNECTING);
> +	ishtp_cl_disconnect(cros_ish_cl);
> +	ishtp_cl_unlink(cros_ish_cl);
> +	ishtp_cl_flush_queues(cros_ish_cl);
> +	ishtp_put_device(cl_device);
> +end_ishtp_cl_init_error:
> +	ishtp_cl_free(cros_ish_cl);
> +end_ishtp_cl_alloc_error:
> +	up_write(&init_lock);
> +	return rv;
> +}
> +
> +/**
> + * cros_ec_ishtp_remove() - ISHTP client driver remove callback
> + * @cl_device:		ISHTP client device instance
> + *
> + * Return: 0
> + */
> +static int cros_ec_ishtp_remove(struct ishtp_cl_device *cl_device)
> +{
> +	struct ishtp_cl	*cros_ish_cl = ishtp_get_drvdata(cl_device);
> +	struct ishtp_cl_data *client_data = ishtp_get_client_data(cros_ish_cl);
> +
> +	cancel_work_sync(&client_data->work_ishtp_reset);
> +	cancel_work_sync(&client_data->work_ec_evt);
> +	cros_ish_deinit(cros_ish_cl);
> +	ishtp_put_device(cl_device);
> +
> +	return 0;
> +}
> +
> +/**
> + * cros_ec_ishtp_reset() - ISHTP client driver reset callback
> + * @cl_device:		ISHTP client device instance
> + *
> + * Return: 0
> + */
> +static int cros_ec_ishtp_reset(struct ishtp_cl_device *cl_device)
> +{
> +	struct ishtp_cl	*cros_ish_cl = ishtp_get_drvdata(cl_device);
> +	struct ishtp_cl_data *client_data = ishtp_get_client_data(cros_ish_cl);
> +
> +	schedule_work(&client_data->work_ishtp_reset);
> +
> +	return 0;
> +}
> +
> +/**
> + * cros_ec_ishtp_suspend() - ISHTP client driver suspend callback
> + * @device:	device instance
> + *
> + * Return: 0 for success, negative error code for failure.
> + */
> +static int __maybe_unused cros_ec_ishtp_suspend(struct device *device)
> +{
> +	struct ishtp_cl_device *cl_device = dev_get_drvdata(device);
> +	struct ishtp_cl	*cros_ish_cl = ishtp_get_drvdata(cl_device);
> +	struct ishtp_cl_data *client_data = ishtp_get_client_data(cros_ish_cl);
> +
> +	return cros_ec_suspend(client_data->ec_dev);
> +}
> +
> +/**
> + * cros_ec_ishtp_resume() - ISHTP client driver resume callback
> + * @device:	device instance
> + *
> + * Return: 0 for success, negative error code for failure.
> + */
> +static int __maybe_unused cros_ec_ishtp_resume(struct device *device)
> +{
> +	struct ishtp_cl_device *cl_device = dev_get_drvdata(device);
> +	struct ishtp_cl	*cros_ish_cl = ishtp_get_drvdata(cl_device);
> +	struct ishtp_cl_data *client_data = ishtp_get_client_data(cros_ish_cl);
> +
> +	return cros_ec_resume(client_data->ec_dev);
> +}
> +
> +static SIMPLE_DEV_PM_OPS(cros_ec_ishtp_pm_ops, cros_ec_ishtp_suspend,
> +			 cros_ec_ishtp_resume);
> +
> +static struct ishtp_cl_driver	cros_ec_ishtp_driver = {
> +	.name = "cros_ec_ishtp",
> +	.guid = &cros_ish_guid,
> +	.probe = cros_ec_ishtp_probe,
> +	.remove = cros_ec_ishtp_remove,
> +	.reset = cros_ec_ishtp_reset,
> +	.driver = {
> +		.pm = &cros_ec_ishtp_pm_ops,
> +	},
> +};
> +
> +static int __init cros_ec_ishtp_mod_init(void)
> +{
> +	return ishtp_cl_driver_register(&cros_ec_ishtp_driver, THIS_MODULE);
> +}
> +
> +static void __exit cros_ec_ishtp_mod_exit(void)
> +{
> +	ishtp_cl_driver_unregister(&cros_ec_ishtp_driver);
> +}
> +
> +module_init(cros_ec_ishtp_mod_init);
> +module_exit(cros_ec_ishtp_mod_exit);
> +
> +MODULE_DESCRIPTION("ChromeOS EC ISHTP Client Driver");
> +MODULE_AUTHOR("Rushikesh S Kadam <rushikesh.s.kadam@intel.com>");
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("ishtp:*");
> 

Remember to run:

scripts/kernel-doc -v -none drivers/platform/chrome/cros_ec_ishtp.c

and

scripts/checkpatch.pl --strict -f drivers/platform/chrome/cros_ec_ishtp.c

before send the patch.

Thanks,
 Enric