[mirror_ubuntu-zesty-kernel.git] / drivers / mfd / cros_ec_spi.c

/*
 * ChromeOS EC multi-function device (SPI)
 *
 * Copyright (C) 2012 Google, Inc
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mfd/cros_ec.h>
#include <linux/mfd/cros_ec_commands.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>


/* The header byte, which follows the preamble */
#define EC_MSG_HEADER			0xec

/*
 * Number of EC preamble bytes we read at a time. Since it takes
 * about 400-500us for the EC to respond there is not a lot of
 * point in tuning this. If the EC could respond faster then
 * we could increase this so that might expect the preamble and
 * message to occur in a single transaction. However, the maximum
 * SPI transfer size is 256 bytes, so at 5MHz we need a response
 * time of perhaps <320us (200 bytes / 1600 bits).
 */
#define EC_MSG_PREAMBLE_COUNT		32

/*
 * Allow for a long time for the EC to respond.  We support i2c
 * tunneling and support fairly long messages for the tunnel (249
 * bytes long at the moment).  If we're talking to a 100 kHz device
 * on the other end and need to transfer ~256 bytes, then we need:
 *  10 us/bit * ~10 bits/byte * ~256 bytes = ~25ms
 *
 * We'll wait 4 times that to handle clock stretching and other
 * paranoia.
 *
 * It's pretty unlikely that we'll really see a 249 byte tunnel in
 * anything other than testing.  If this was more common we might
 * consider having slow commands like this require a GET_STATUS
 * wait loop.  The 'flash write' command would be another candidate
 * for this, clocking in at 2-3ms.
 */
#define EC_MSG_DEADLINE_MS		100

/*
  * Time between raising the SPI chip select (for the end of a
  * transaction) and dropping it again (for the next transaction).
  * If we go too fast, the EC will miss the transaction. We know that we
  * need at least 70 us with the 16 MHz STM32 EC, so go with 200 us to be
  * safe.
  */
#define EC_SPI_RECOVERY_TIME_NS	(200 * 1000)

/**
 * struct cros_ec_spi - information about a SPI-connected EC
 *
 * @spi: SPI device we are connected to
 * @last_transfer_ns: time that we last finished a transfer, or 0 if there
 *	if no record
 * @end_of_msg_delay: used to set the delay_usecs on the spi_transfer that
 *      is sent when we want to turn off CS at the end of a transaction.
 * @lock: mutex to ensure only one user of cros_ec_cmd_xfer_spi at a time
 */
struct cros_ec_spi {
	struct spi_device *spi;
	s64 last_transfer_ns;
	unsigned int end_of_msg_delay;
	struct mutex lock;
};

static void debug_packet(struct device *dev, const char *name, u8 *ptr,
			  int len)
{
#ifdef DEBUG
	int i;

	dev_dbg(dev, "%s: ", name);
	for (i = 0; i < len; i++)
		pr_cont(" %02x", ptr[i]);

	pr_cont("\n");
#endif
}

/**
 * cros_ec_spi_receive_response - Receive a response 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_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;

	/* 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);
			return ret;
		}

		for (end = ptr + EC_MSG_PREAMBLE_COUNT; ptr != end; ptr++) {
			if (*ptr == EC_MSG_HEADER) {
				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;

	/* 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);

		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);
			return ret;
		}

		debug_packet(ec_dev->dev, "interim", ptr, todo);
		ptr += todo;
		need_len -= todo;
	}

	dev_dbg(ec_dev->dev, "loop done, ptr=%zd\n", ptr - ec_dev->din);

	return 0;
}

/**
 * cros_ec_cmd_xfer_spi - Transfer a message over SPI and receive the reply
 *
 * @ec_dev: ChromeOS EC device
 * @ec_msg: Message to transfer
 */
static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
				struct cros_ec_command *ec_msg)
{
	struct cros_ec_spi *ec_spi = ec_dev->priv;
	struct spi_transfer trans;
	struct spi_message msg;
	int i, len;
	u8 *ptr;
	int sum;
	int ret = 0, final_ret;

	/*
	 * We have the shared ec_dev buffer plus we do lots of separate spi_sync
	 * calls, so we need to make sure only one person is using this at a
	 * time.
	 */
	mutex_lock(&ec_spi->lock);

	len = cros_ec_prepare_tx(ec_dev, ec_msg);
	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);
	}

	/* 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.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) {
		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();
	if (!ret)
		ret = final_ret;
	if (ret < 0) {
		dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
		goto exit;
	}

	ptr = ec_dev->din;

	/* check response error code */
	ec_msg->result = ptr[0];
	ret = cros_ec_check_result(ec_dev, ec_msg);
	if (ret)
		goto exit;

	len = ptr[1];
	sum = ptr[0] + ptr[1];
	if (len > ec_msg->insize) {
		dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
			len, ec_msg->insize);
		ret = -ENOSPC;
		goto exit;
	}

	/* copy response packet payload and compute checksum */
	for (i = 0; i < len; i++) {
		sum += ptr[i + 2];
		if (ec_msg->insize)
			ec_msg->indata[i] = ptr[i + 2];
	}
	sum &= 0xff;

	debug_packet(ec_dev->dev, "in", ptr, len + 3);

	if (sum != ptr[len + 2]) {
		dev_err(ec_dev->dev,
			"bad packet checksum, expected %02x, got %02x\n",
			sum, ptr[len + 2]);
		ret = -EBADMSG;
		goto exit;
	}

	ret = len;
exit:
	mutex_unlock(&ec_spi->lock);
	return ret;
}

static void cros_ec_spi_dt_probe(struct cros_ec_spi *ec_spi, struct device *dev)
{
	struct device_node *np = dev->of_node;
	u32 val;
	int ret;

	ret = of_property_read_u32(np, "google,cros-ec-spi-msg-delay", &val);
	if (!ret)
		ec_spi->end_of_msg_delay = val;
}

static int cros_ec_spi_probe(struct spi_device *spi)
{
	struct device *dev = &spi->dev;
	struct cros_ec_device *ec_dev;
	struct cros_ec_spi *ec_spi;
	int err;

	spi->bits_per_word = 8;
	spi->mode = SPI_MODE_0;
	err = spi_setup(spi);
	if (err < 0)
		return err;

	ec_spi = devm_kzalloc(dev, sizeof(*ec_spi), GFP_KERNEL);
	if (ec_spi == NULL)
		return -ENOMEM;
	ec_spi->spi = spi;
	mutex_init(&ec_spi->lock);
	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
	if (!ec_dev)
		return -ENOMEM;

	/* Check for any DT properties */
	cros_ec_spi_dt_probe(ec_spi, dev);

	spi_set_drvdata(spi, ec_dev);
	ec_dev->dev = dev;
	ec_dev->priv = ec_spi;
	ec_dev->irq = spi->irq;
	ec_dev->cmd_xfer = cros_ec_cmd_xfer_spi;
	ec_dev->ec_name = ec_spi->spi->modalias;
	ec_dev->phys_name = dev_name(&ec_spi->spi->dev);
	ec_dev->parent = &ec_spi->spi->dev;
	ec_dev->din_size = EC_MSG_BYTES + EC_MSG_PREAMBLE_COUNT;
	ec_dev->dout_size = EC_MSG_BYTES;

	err = cros_ec_register(ec_dev);
	if (err) {
		dev_err(dev, "cannot register EC\n");
		return err;
	}

	device_init_wakeup(&spi->dev, true);

	return 0;
}

static int cros_ec_spi_remove(struct spi_device *spi)
{
	struct cros_ec_device *ec_dev;

	ec_dev = spi_get_drvdata(spi);
	cros_ec_remove(ec_dev);

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int cros_ec_spi_suspend(struct device *dev)
{
	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);

	return cros_ec_suspend(ec_dev);
}

static int cros_ec_spi_resume(struct device *dev)
{
	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);

	return cros_ec_resume(ec_dev);
}
#endif

static SIMPLE_DEV_PM_OPS(cros_ec_spi_pm_ops, cros_ec_spi_suspend,
			 cros_ec_spi_resume);

static const struct spi_device_id cros_ec_spi_id[] = {
	{ "cros-ec-spi", 0 },
	{ }
};
MODULE_DEVICE_TABLE(spi, cros_ec_spi_id);

static struct spi_driver cros_ec_driver_spi = {
	.driver	= {
		.name	= "cros-ec-spi",
		.owner	= THIS_MODULE,
		.pm	= &cros_ec_spi_pm_ops,
	},
	.probe		= cros_ec_spi_probe,
	.remove		= cros_ec_spi_remove,
	.id_table	= cros_ec_spi_id,
};

module_spi_driver(cros_ec_driver_spi);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("ChromeOS EC multi function device (SPI)");
Commit	Line	Data
a17d94f0 SG	1	/*
	2	* ChromeOS EC multi-function device (SPI)
	3	*
	4	* Copyright (C) 2012 Google, Inc
	5	*
	6	* This software is licensed under the terms of the GNU General Public
	7	* License version 2, as published by the Free Software Foundation, and
	8	* may be copied, distributed, and modified under those terms.
	9	*
	10	* This program is distributed in the hope that it will be useful,
	11	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	13	* GNU General Public License for more details.
	14	*/
	15
	16	#include <linux/delay.h>
	17	#include <linux/kernel.h>
	18	#include <linux/module.h>
	19	#include <linux/mfd/cros_ec.h>
	20	#include <linux/mfd/cros_ec_commands.h>
01e73c89	21	#include <linux/of.h>
a17d94f0 SG	22	#include <linux/platform_device.h>
	23	#include <linux/slab.h>
	24	#include <linux/spi/spi.h>
	25
	26
	27	/* The header byte, which follows the preamble */
	28	#define EC_MSG_HEADER 0xec
	29
	30	/*
	31	* Number of EC preamble bytes we read at a time. Since it takes
	32	* about 400-500us for the EC to respond there is not a lot of
	33	* point in tuning this. If the EC could respond faster then
	34	* we could increase this so that might expect the preamble and
	35	* message to occur in a single transaction. However, the maximum
	36	* SPI transfer size is 256 bytes, so at 5MHz we need a response
	37	* time of perhaps <320us (200 bytes / 1600 bits).
	38	*/
	39	#define EC_MSG_PREAMBLE_COUNT 32
	40
	41	/*
9c0b54a1 DA	42	* Allow for a long time for the EC to respond. We support i2c
	43	* tunneling and support fairly long messages for the tunnel (249
	44	* bytes long at the moment). If we're talking to a 100 kHz device
	45	* on the other end and need to transfer ~256 bytes, then we need:
	46	* 10 us/bit * ~10 bits/byte * ~256 bytes = ~25ms
	47	*
	48	* We'll wait 4 times that to handle clock stretching and other
	49	* paranoia.
	50	*
	51	* It's pretty unlikely that we'll really see a 249 byte tunnel in
	52	* anything other than testing. If this was more common we might
	53	* consider having slow commands like this require a GET_STATUS
	54	* wait loop. The 'flash write' command would be another candidate
	55	* for this, clocking in at 2-3ms.
	56	*/
	57	#define EC_MSG_DEADLINE_MS 100
a17d94f0 SG	58
	59	/*
	60	* Time between raising the SPI chip select (for the end of a
	61	* transaction) and dropping it again (for the next transaction).
49f91ac3 DB	62	* If we go too fast, the EC will miss the transaction. We know that we
	63	* need at least 70 us with the 16 MHz STM32 EC, so go with 200 us to be
	64	* safe.
a17d94f0	65	*/
49f91ac3	66	#define EC_SPI_RECOVERY_TIME_NS (200 * 1000)
a17d94f0 SG	67
	68	/**
	69	* struct cros_ec_spi - information about a SPI-connected EC
	70	*
	71	* @spi: SPI device we are connected to
	72	* @last_transfer_ns: time that we last finished a transfer, or 0 if there
	73	* if no record
01e73c89 RK	74	* @end_of_msg_delay: used to set the delay_usecs on the spi_transfer that
01e73c89 RK	75	* is sent when we want to turn off CS at the end of a transaction.
7e6cb5b4	76	* @lock: mutex to ensure only one user of cros_ec_cmd_xfer_spi at a time
a17d94f0 SG	77	*/
	78	struct cros_ec_spi {
	79	struct spi_device *spi;
	80	s64 last_transfer_ns;
01e73c89	81	unsigned int end_of_msg_delay;
362196e5	82	struct mutex lock;
a17d94f0 SG	83	};
	84
	85	static void debug_packet(struct device dev, const char name, u8 *ptr,
	86	int len)
	87	{
	88	#ifdef DEBUG
	89	int i;
	90
	91	dev_dbg(dev, "%s: ", name);
	92	for (i = 0; i < len; i++)
9e146f43 TR	93	pr_cont(" %02x", ptr[i]);
	94
	95	pr_cont("\n");
a17d94f0 SG	96	#endif
	97	}
	98
	99	/**
	100	* cros_ec_spi_receive_response - Receive a response from the EC.
	101	*
	102	* This function has two phases: reading the preamble bytes (since if we read
	103	* data from the EC before it is ready to send, we just get preamble) and
	104	* reading the actual message.
	105	*
	106	* The received data is placed into ec_dev->din.
	107	*
	108	* @ec_dev: ChromeOS EC device
	109	* @need_len: Number of message bytes we need to read
	110	*/
	111	static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev,
	112	int need_len)
	113	{
	114	struct cros_ec_spi *ec_spi = ec_dev->priv;
	115	struct spi_transfer trans;
	116	struct spi_message msg;
	117	u8 ptr, end;
	118	int ret;
	119	unsigned long deadline;
	120	int todo;
	121
	122	/* Receive data until we see the header byte */
	123	deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS);
c9a81d67 DA	124	while (true) {
	125	unsigned long start_jiffies = jiffies;
	126
daf93d22	127	memset(&trans, 0, sizeof(trans));
a17d94f0 SG	128	trans.cs_change = 1;
	129	trans.rx_buf = ptr = ec_dev->din;
	130	trans.len = EC_MSG_PREAMBLE_COUNT;
	131
	132	spi_message_init(&msg);
	133	spi_message_add_tail(&trans, &msg);
	134	ret = spi_sync(ec_spi->spi, &msg);
	135	if (ret < 0) {
	136	dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
	137	return ret;
	138	}
	139
	140	for (end = ptr + EC_MSG_PREAMBLE_COUNT; ptr != end; ptr++) {
	141	if (*ptr == EC_MSG_HEADER) {
c34924b9	142	dev_dbg(ec_dev->dev, "msg found at %zd\n",
a17d94f0 SG	143	ptr - ec_dev->din);
	144	break;
	145	}
	146	}
c9a81d67 DA	147	if (ptr != end)
c9a81d67 DA	148	break;
a17d94f0	149
c9a81d67 DA	150	/*
	151	* Use the time at the start of the loop as a timeout. This
	152	* gives us one last shot at getting the transfer and is useful
	153	* in case we got context switched out for a while.
	154	*/
	155	if (time_after(start_jiffies, deadline)) {
a17d94f0 SG	156	dev_warn(ec_dev->dev, "EC failed to respond in time\n");
	157	return -ETIMEDOUT;
	158	}
c9a81d67	159	}
a17d94f0 SG	160
	161	/*
	162	* ptr now points to the header byte. Copy any valid data to the
	163	* start of our buffer
	164	*/
	165	todo = end - ++ptr;
	166	BUG_ON(todo < 0 \|\| todo > ec_dev->din_size);
	167	todo = min(todo, need_len);
	168	memmove(ec_dev->din, ptr, todo);
	169	ptr = ec_dev->din + todo;
	170	dev_dbg(ec_dev->dev, "need %d, got %d bytes from preamble\n",
	171	need_len, todo);
	172	need_len -= todo;
	173
	174	/* Receive data until we have it all */
	175	while (need_len > 0) {
	176	/*
	177	* We can't support transfers larger than the SPI FIFO size
	178	* unless we have DMA. We don't have DMA on the ISP SPI ports
	179	* for Exynos. We need a way of asking SPI driver for
	180	* maximum-supported transfer size.
	181	*/
	182	todo = min(need_len, 256);
c34924b9	183	dev_dbg(ec_dev->dev, "loop, todo=%d, need_len=%d, ptr=%zd\n",
a17d94f0 SG	184	todo, need_len, ptr - ec_dev->din);
a17d94f0 SG	185
daf93d22	186	memset(&trans, 0, sizeof(trans));
a17d94f0 SG	187	trans.cs_change = 1;
	188	trans.rx_buf = ptr;
	189	trans.len = todo;
	190	spi_message_init(&msg);
	191	spi_message_add_tail(&trans, &msg);
	192
	193	/* send command to EC and read answer */
	194	BUG_ON((u8 *)trans.rx_buf - ec_dev->din + todo >
	195	ec_dev->din_size);
	196	ret = spi_sync(ec_spi->spi, &msg);
	197	if (ret < 0) {
	198	dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
	199	return ret;
	200	}
	201
	202	debug_packet(ec_dev->dev, "interim", ptr, todo);
	203	ptr += todo;
	204	need_len -= todo;
	205	}
	206
c34924b9	207	dev_dbg(ec_dev->dev, "loop done, ptr=%zd\n", ptr - ec_dev->din);
a17d94f0 SG	208
	209	return 0;
	210	}
	211
	212	/**
7e6cb5b4	213	* cros_ec_cmd_xfer_spi - Transfer a message over SPI and receive the reply
a17d94f0 SG	214	*
	215	* @ec_dev: ChromeOS EC device
	216	* @ec_msg: Message to transfer
	217	*/
7e6cb5b4	218	static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
5d4773e2	219	struct cros_ec_command *ec_msg)
a17d94f0 SG	220	{
	221	struct cros_ec_spi *ec_spi = ec_dev->priv;
	222	struct spi_transfer trans;
	223	struct spi_message msg;
	224	int i, len;
	225	u8 *ptr;
	226	int sum;
	227	int ret = 0, final_ret;
a17d94f0	228
362196e5 DA	229	/*
	230	* We have the shared ec_dev buffer plus we do lots of separate spi_sync
	231	* calls, so we need to make sure only one person is using this at a
	232	* time.
	233	*/
	234	mutex_lock(&ec_spi->lock);
	235
a17d94f0 SG	236	len = cros_ec_prepare_tx(ec_dev, ec_msg);
	237	dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
	238
	239	/* If it's too soon to do another transaction, wait */
	240	if (ec_spi->last_transfer_ns) {
a17d94f0 SG	241	unsigned long delay; /* The delay completed so far */
a17d94f0 SG	242
154adc14	243	delay = ktime_get_ns() - ec_spi->last_transfer_ns;
a17d94f0	244	if (delay < EC_SPI_RECOVERY_TIME_NS)
1fe36866	245	ndelay(EC_SPI_RECOVERY_TIME_NS - delay);
a17d94f0 SG	246	}
	247
	248	/* Transmit phase - send our message */
	249	debug_packet(ec_dev->dev, "out", ec_dev->dout, len);
daf93d22	250	memset(&trans, 0, sizeof(trans));
a17d94f0 SG	251	trans.tx_buf = ec_dev->dout;
	252	trans.len = len;
	253	trans.cs_change = 1;
	254	spi_message_init(&msg);
	255	spi_message_add_tail(&trans, &msg);
	256	ret = spi_sync(ec_spi->spi, &msg);
	257
	258	/* Get the response */
	259	if (!ret) {
	260	ret = cros_ec_spi_receive_response(ec_dev,
5d4773e2	261	ec_msg->insize + EC_MSG_TX_PROTO_BYTES);
a17d94f0 SG	262	} else {
	263	dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
	264	}
	265
96758059 DA	266	/*
	267	* Turn off CS, possibly adding a delay to ensure the rising edge
	268	* doesn't come too soon after the end of the data.
	269	*/
a17d94f0	270	spi_message_init(&msg);
96758059 DA	271	memset(&trans, 0, sizeof(trans));
	272	trans.delay_usecs = ec_spi->end_of_msg_delay;
	273	spi_message_add_tail(&trans, &msg);
01e73c89	274
a17d94f0	275	final_ret = spi_sync(ec_spi->spi, &msg);
154adc14	276	ec_spi->last_transfer_ns = ktime_get_ns();
a17d94f0 SG	277	if (!ret)
	278	ret = final_ret;
	279	if (ret < 0) {
	280	dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
362196e5	281	goto exit;
a17d94f0 SG	282	}
a17d94f0 SG	283
a17d94f0	284	ptr = ec_dev->din;
6db07b63 BR	285
	286	/* check response error code */
	287	ec_msg->result = ptr[0];
	288	ret = cros_ec_check_result(ec_dev, ec_msg);
	289	if (ret)
362196e5	290	goto exit;
6db07b63	291
a17d94f0 SG	292	len = ptr[1];
a17d94f0 SG	293	sum = ptr[0] + ptr[1];
5d4773e2	294	if (len > ec_msg->insize) {
a17d94f0	295	dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
5d4773e2	296	len, ec_msg->insize);
362196e5 DA	297	ret = -ENOSPC;
362196e5 DA	298	goto exit;
a17d94f0 SG	299	}
	300
	301	/* copy response packet payload and compute checksum */
	302	for (i = 0; i < len; i++) {
	303	sum += ptr[i + 2];
5d4773e2 BR	304	if (ec_msg->insize)
5d4773e2 BR	305	ec_msg->indata[i] = ptr[i + 2];
a17d94f0 SG	306	}
	307	sum &= 0xff;
	308
	309	debug_packet(ec_dev->dev, "in", ptr, len + 3);
	310
	311	if (sum != ptr[len + 2]) {
	312	dev_err(ec_dev->dev,
	313	"bad packet checksum, expected %02x, got %02x\n",
	314	sum, ptr[len + 2]);
362196e5 DA	315	ret = -EBADMSG;
362196e5 DA	316	goto exit;
a17d94f0 SG	317	}
a17d94f0 SG	318
12ebc8a5	319	ret = len;
362196e5 DA	320	exit:
	321	mutex_unlock(&ec_spi->lock);
	322	return ret;
a17d94f0 SG	323	}
a17d94f0 SG	324
01e73c89 RK	325	static void cros_ec_spi_dt_probe(struct cros_ec_spi ec_spi, struct device dev)
	326	{
	327	struct device_node *np = dev->of_node;
	328	u32 val;
	329	int ret;
	330
	331	ret = of_property_read_u32(np, "google,cros-ec-spi-msg-delay", &val);
	332	if (!ret)
	333	ec_spi->end_of_msg_delay = val;
	334	}
	335
9922b412	336	static int cros_ec_spi_probe(struct spi_device *spi)
a17d94f0 SG	337	{
	338	struct device *dev = &spi->dev;
	339	struct cros_ec_device *ec_dev;
	340	struct cros_ec_spi *ec_spi;
	341	int err;
	342
	343	spi->bits_per_word = 8;
	344	spi->mode = SPI_MODE_0;
	345	err = spi_setup(spi);
	346	if (err < 0)
	347	return err;
	348
	349	ec_spi = devm_kzalloc(dev, sizeof(*ec_spi), GFP_KERNEL);
	350	if (ec_spi == NULL)
	351	return -ENOMEM;
	352	ec_spi->spi = spi;
362196e5	353	mutex_init(&ec_spi->lock);
a17d94f0 SG	354	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
	355	if (!ec_dev)
	356	return -ENOMEM;
	357
01e73c89 RK	358	/* Check for any DT properties */
	359	cros_ec_spi_dt_probe(ec_spi, dev);
	360
a17d94f0	361	spi_set_drvdata(spi, ec_dev);
a17d94f0 SG	362	ec_dev->dev = dev;
	363	ec_dev->priv = ec_spi;
	364	ec_dev->irq = spi->irq;
7e6cb5b4	365	ec_dev->cmd_xfer = cros_ec_cmd_xfer_spi;
a17d94f0 SG	366	ec_dev->ec_name = ec_spi->spi->modalias;
	367	ec_dev->phys_name = dev_name(&ec_spi->spi->dev);
	368	ec_dev->parent = &ec_spi->spi->dev;
	369	ec_dev->din_size = EC_MSG_BYTES + EC_MSG_PREAMBLE_COUNT;
	370	ec_dev->dout_size = EC_MSG_BYTES;
	371
	372	err = cros_ec_register(ec_dev);
	373	if (err) {
	374	dev_err(dev, "cannot register EC\n");
	375	return err;
	376	}
	377
fb50497c P	378	device_init_wakeup(&spi->dev, true);
fb50497c P	379
a17d94f0 SG	380	return 0;
	381	}
	382
9922b412	383	static int cros_ec_spi_remove(struct spi_device *spi)
a17d94f0 SG	384	{
	385	struct cros_ec_device *ec_dev;
	386
	387	ec_dev = spi_get_drvdata(spi);
	388	cros_ec_remove(ec_dev);
	389
	390	return 0;
	391	}
	392
	393	#ifdef CONFIG_PM_SLEEP
	394	static int cros_ec_spi_suspend(struct device *dev)
	395	{
	396	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
	397
	398	return cros_ec_suspend(ec_dev);
	399	}
	400
	401	static int cros_ec_spi_resume(struct device *dev)
	402	{
	403	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
	404
	405	return cros_ec_resume(ec_dev);
	406	}
	407	#endif
	408
	409	static SIMPLE_DEV_PM_OPS(cros_ec_spi_pm_ops, cros_ec_spi_suspend,
	410	cros_ec_spi_resume);
	411
	412	static const struct spi_device_id cros_ec_spi_id[] = {
	413	{ "cros-ec-spi", 0 },
	414	{ }
	415	};
	416	MODULE_DEVICE_TABLE(spi, cros_ec_spi_id);
	417
	418	static struct spi_driver cros_ec_driver_spi = {
	419	.driver = {
	420	.name = "cros-ec-spi",
	421	.owner = THIS_MODULE,
	422	.pm = &cros_ec_spi_pm_ops,
	423	},
9922b412 TR	424	.probe = cros_ec_spi_probe,
9922b412 TR	425	.remove = cros_ec_spi_remove,
a17d94f0 SG	426	.id_table = cros_ec_spi_id,
	427	};
	428
	429	module_spi_driver(cros_ec_driver_spi);
	430
ea0f8b0b	431	MODULE_LICENSE("GPL v2");
a17d94f0	432	MODULE_DESCRIPTION("ChromeOS EC multi function device (SPI)");