platform/chrome: Move cros-ec transport drivers to drivers/platform.

There are some cros-ec transport drivers (I2C, SPI) living in MFD, while
others (LPC) living in drivers/platform. The transport drivers are more
platform specific. So, move the I2C and SPI transport drivers to the
platform/chrome directory. The patch also removes the MFD_ prefix of
their Kconfig symbols.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Benson Leung <bleung@chromium.org>

4 files changed, 1151 insertions, 0 deletions

diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index cb0df9eb3e0f..16b1615958aa 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -52,6 +52,26 @@ config CHROMEOS_TBMC
 config CROS_EC_CTL
         tristate
 
+config CROS_EC_I2C
+	tristate "ChromeOS Embedded Controller (I2C)"
+	depends on MFD_CROS_EC && I2C
+
+	help
+	  If you say Y here, you get support for talking to the ChromeOS
+	  EC through an I2C bus. This uses a simple byte-level protocol with
+	  a checksum. Failing accesses will be retried three times to
+	  improve reliability.
+
+config CROS_EC_SPI
+	tristate "ChromeOS Embedded Controller (SPI)"
+	depends on MFD_CROS_EC && SPI
+
+	---help---
+	  If you say Y here, you get support for talking to the ChromeOS EC
+	  through a SPI bus, using a byte-level protocol. Since the EC's
+	  response time cannot be guaranteed, we support ignoring
+	  'pre-amble' bytes before the response actually starts.
+
 config CROS_EC_LPC
         tristate "ChromeOS Embedded Controller (LPC)"
         depends on MFD_CROS_EC && ACPI && (X86 || COMPILE_TEST)
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index e44c37a63fa9..cd591bf872bb 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -6,6 +6,8 @@ obj-$(CONFIG_CHROMEOS_TBMC)		+= chromeos_tbmc.o
 cros_ec_ctl-objs			:= cros_ec_sysfs.o cros_ec_lightbar.o \
 					   cros_ec_vbc.o cros_ec_debugfs.o
 obj-$(CONFIG_CROS_EC_CTL)		+= cros_ec_ctl.o
+obj-$(CONFIG_CROS_EC_I2C)		+= cros_ec_i2c.o
+obj-$(CONFIG_CROS_EC_SPI)		+= cros_ec_spi.o
 cros_ec_lpcs-objs			:= cros_ec_lpc.o cros_ec_lpc_reg.o
 cros_ec_lpcs-$(CONFIG_CROS_EC_LPC_MEC)	+= cros_ec_lpc_mec.o
 obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpcs.o
diff --git a/drivers/platform/chrome/cros_ec_i2c.c b/drivers/platform/chrome/cros_ec_i2c.c
new file mode 100644
index 000000000000..ef9b4763356f
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_i2c.c
@@ -0,0 +1,386 @@
+/*
+ * ChromeOS EC multi-function device (I2C)
+ *
+ * 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/acpi.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/mfd/cros_ec_commands.h>
+#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);
+
+	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)
+{
+	struct i2c_client *client = ec_dev->priv;
+	int ret = -ENOMEM;
+	int i;
+	int len;
+	int packet_len;
+	u8 *out_buf = NULL;
+	u8 *in_buf = NULL;
+	u8 sum;
+	struct i2c_msg i2c_msg[2];
+
+	i2c_msg[0].addr = client->addr;
+	i2c_msg[0].flags = 0;
+	i2c_msg[1].addr = client->addr;
+	i2c_msg[1].flags = I2C_M_RD;
+
+	/*
+	 * allocate larger packet (one byte for checksum, one byte for
+	 * length, and one for result code)
+	 */
+	packet_len = msg->insize + 3;
+	in_buf = kzalloc(packet_len, GFP_KERNEL);
+	if (!in_buf)
+		goto done;
+	i2c_msg[1].len = packet_len;
+	i2c_msg[1].buf = (char *)in_buf;
+
+	/*
+	 * allocate larger packet (one byte for checksum, one for
+	 * command code, one for length, and one for command version)
+	 */
+	packet_len = msg->outsize + 4;
+	out_buf = kzalloc(packet_len, GFP_KERNEL);
+	if (!out_buf)
+		goto done;
+	i2c_msg[0].len = packet_len;
+	i2c_msg[0].buf = (char *)out_buf;
+
+	out_buf[0] = EC_CMD_VERSION0 + msg->version;
+	out_buf[1] = msg->command;
+	out_buf[2] = msg->outsize;
+
+	/* copy message payload and compute checksum */
+	sum = out_buf[0] + out_buf[1] + out_buf[2];
+	for (i = 0; i < msg->outsize; i++) {
+		out_buf[3 + i] = msg->data[i];
+		sum += out_buf[3 + i];
+	}
+	out_buf[3 + msg->outsize] = sum;
+
+	/* send command to EC and read answer */
+	ret = i2c_transfer(client->adapter, i2c_msg, 2);
+	if (ret < 0) {
+		dev_err(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;
+	}
+
+	/* check response error code */
+	msg->result = i2c_msg[1].buf[0];
+	ret = cros_ec_check_result(ec_dev, msg);
+	if (ret)
+		goto done;
+
+	len = in_buf[1];
+	if (len > msg->insize) {
+		dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
+			len, msg->insize);
+		ret = -ENOSPC;
+		goto done;
+	}
+
+	/* copy response packet payload and compute checksum */
+	sum = in_buf[0] + in_buf[1];
+	for (i = 0; i < len; i++) {
+		msg->data[i] = in_buf[2 + i];
+		sum += in_buf[2 + i];
+	}
+	dev_dbg(ec_dev->dev, "packet: %*ph, sum = %02x\n",
+		i2c_msg[1].len, in_buf, sum);
+	if (sum != in_buf[2 + len]) {
+		dev_err(ec_dev->dev, "bad packet checksum\n");
+		ret = -EBADMSG;
+		goto done;
+	}
+
+	ret = len;
+done:
+	kfree(in_buf);
+	kfree(out_buf);
+	if (msg->command == EC_CMD_REBOOT_EC)
+		msleep(EC_REBOOT_DELAY_MS);
+
+	return ret;
+}
+
+static int cros_ec_i2c_probe(struct i2c_client *client,
+			     const struct i2c_device_id *dev_id)
+{
+	struct device *dev = &client->dev;
+	struct cros_ec_device *ec_dev = NULL;
+	int err;
+
+	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
+	if (!ec_dev)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, ec_dev);
+	ec_dev->dev = dev;
+	ec_dev->priv = client;
+	ec_dev->irq = client->irq;
+	ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
+	ec_dev->pkt_xfer = cros_ec_pkt_xfer_i2c;
+	ec_dev->phys_name = client->adapter->name;
+	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_i2c);
+
+	err = cros_ec_register(ec_dev);
+	if (err) {
+		dev_err(dev, "cannot register EC\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static int cros_ec_i2c_remove(struct i2c_client *client)
+{
+	struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
+
+	cros_ec_remove(ec_dev);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int cros_ec_i2c_suspend(struct device *dev)
+{
+	struct cros_ec_device *ec_dev = to_ec_dev(dev);
+
+	return cros_ec_suspend(ec_dev);
+}
+
+static int cros_ec_i2c_resume(struct device *dev)
+{
+	struct cros_ec_device *ec_dev = to_ec_dev(dev);
+
+	return cros_ec_resume(ec_dev);
+}
+#endif
+
+static const struct dev_pm_ops cros_ec_i2c_pm_ops = {
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_i2c_suspend, cros_ec_i2c_resume)
+};
+
+#ifdef CONFIG_OF
+static const struct of_device_id cros_ec_i2c_of_match[] = {
+	{ .compatible = "google,cros-ec-i2c", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
+#endif
+
+static const struct i2c_device_id cros_ec_i2c_id[] = {
+	{ "cros-ec-i2c", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id cros_ec_i2c_acpi_id[] = {
+	{ "GOOG0008", 0 },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_acpi_id);
+#endif
+
+static struct i2c_driver cros_ec_driver = {
+	.driver	= {
+		.name	= "cros-ec-i2c",
+		.acpi_match_table = ACPI_PTR(cros_ec_i2c_acpi_id),
+		.of_match_table = of_match_ptr(cros_ec_i2c_of_match),
+		.pm	= &cros_ec_i2c_pm_ops,
+	},
+	.probe		= cros_ec_i2c_probe,
+	.remove		= cros_ec_i2c_remove,
+	.id_table	= cros_ec_i2c_id,
+};
+
+module_i2c_driver(cros_ec_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ChromeOS EC multi function device");
diff --git a/drivers/platform/chrome/cros_ec_spi.c b/drivers/platform/chrome/cros_ec_spi.c
new file mode 100644
index 000000000000..2060d1483043
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_spi.c
@@ -0,0 +1,743 @@
+/*
+ * 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 8 times that to handle clock stretching and other
+ * paranoia.  Note that some battery gas gauge ICs claim to have a
+ * clock stretch of 144ms in rare situations.  That's incentive for
+ * not directly passing i2c through, but it's too late for that for
+ * existing hardware.
+ *
+ * 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		200
+
+/*
+  * 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.
+ * @start_of_msg_delay: used to set the delay_usecs on the spi_transfer that
+ *      is sent when we want to turn on CS at the start of a transaction.
+ * @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.
+ */
+struct cros_ec_spi {
+	struct spi_device *spi;
+	s64 last_transfer_ns;
+	unsigned int start_of_msg_delay;
+	unsigned int end_of_msg_delay;
+};
+
+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
+}
+
+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_locked(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_locked(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_dev->din_size < EC_MSG_PREAMBLE_COUNT);
+
+	/* 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.
+ *
+ * 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)
+{
+	u8 *ptr, *end;
+	int ret;
+	unsigned long deadline;
+	int todo;
+
+	BUG_ON(ec_dev->din_size < EC_MSG_PREAMBLE_COUNT);
+
+	/* 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;
+
+	/* 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;
+
+		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_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_response *response;
+	struct cros_ec_spi *ec_spi = ec_dev->priv;
+	struct spi_transfer trans, trans_delay;
+	struct spi_message msg;
+	int i, len;
+	u8 *ptr;
+	u8 *rx_buf;
+	u8 sum;
+	u8 rx_byte;
+	int ret = 0, final_ret;
+	unsigned long delay;
+
+	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 */
+	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)
+		return -ENOMEM;
+
+	spi_bus_lock(ec_spi->spi->master);
+
+	/*
+	 * Leave a gap between CS assertion and clocking of data to allow the
+	 * EC time to wakeup.
+	 */
+	spi_message_init(&msg);
+	if (ec_spi->start_of_msg_delay) {
+		memset(&trans_delay, 0, sizeof(trans_delay));
+		trans_delay.delay_usecs = ec_spi->start_of_msg_delay;
+		spi_message_add_tail(&trans_delay, &msg);
+	}
+
+	/* 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_add_tail(&trans, &msg);
+	ret = spi_sync_locked(ec_spi->spi, &msg);
+
+	/* Get the response */
+	if (!ret) {
+		/* Verify that EC can process command */
+		for (i = 0; i < len; i++) {
+			rx_byte = rx_buf[i];
+			/*
+			 * Seeing the PAST_END, RX_BAD_DATA, or NOT_READY
+			 * markers are all signs that the EC didn't fully
+			 * receive our command. e.g., if the EC is flashing
+			 * itself, it can't respond to any commands and instead
+			 * clocks out EC_SPI_PAST_END from its SPI hardware
+			 * buffer. Similar occurrences can happen if the AP is
+			 * too slow to clock out data after asserting CS -- the
+			 * EC will abort and fill its buffer with
+			 * EC_SPI_RX_BAD_DATA.
+			 *
+			 * In all cases, these errors should be safe to retry.
+			 * Report -EAGAIN and let the caller decide what to do
+			 * about that.
+			 */
+			if (rx_byte == EC_SPI_PAST_END  ||
+			    rx_byte == EC_SPI_RX_BAD_DATA ||
+			    rx_byte == EC_SPI_NOT_READY) {
+				ret = -EAGAIN;
+				break;
+			}
+		}
+	}
+
+	if (!ret)
+		ret = cros_ec_spi_receive_packet(ec_dev,
+				ec_msg->insize + sizeof(*response));
+	else if (ret != -EAGAIN)
+		dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
+
+	final_ret = terminate_request(ec_dev);
+
+	spi_bus_unlock(ec_spi->spi->master);
+
+	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
+ * @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;
+	u8 *rx_buf;
+	u8 rx_byte;
+	int sum;
+	int ret = 0, final_ret;
+	unsigned long delay;
+
+	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 */
+	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)
+		return -ENOMEM;
+
+	spi_bus_lock(ec_spi->spi->master);
+
+	/* 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);
+	spi_message_add_tail(&trans, &msg);
+	ret = spi_sync_locked(ec_spi->spi, &msg);
+
+	/* Get the response */
+	if (!ret) {
+		/* Verify that EC can process command */
+		for (i = 0; i < len; i++) {
+			rx_byte = rx_buf[i];
+			/* See comments in cros_ec_pkt_xfer_spi() */
+			if (rx_byte == EC_SPI_PAST_END  ||
+			    rx_byte == EC_SPI_RX_BAD_DATA ||
+			    rx_byte == EC_SPI_NOT_READY) {
+				ret = -EAGAIN;
+				break;
+			}
+		}
+	}
+
+	if (!ret)
+		ret = cros_ec_spi_receive_response(ec_dev,
+				ec_msg->insize + EC_MSG_TX_PROTO_BYTES);
+	else if (ret != -EAGAIN)
+		dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
+
+	final_ret = terminate_request(ec_dev);
+
+	spi_bus_unlock(ec_spi->spi->master);
+
+	if (!ret)
+		ret = final_ret;
+	if (ret < 0)
+		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->data[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:
+	kfree(rx_buf);
+	if (ec_msg->command == EC_CMD_REBOOT_EC)
+		msleep(EC_REBOOT_DELAY_MS);
+
+	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-pre-delay", &val);
+	if (!ret)
+		ec_spi->start_of_msg_delay = val;
+
+	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;
+	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->pkt_xfer = cros_ec_pkt_xfer_spi;
+	ec_dev->phys_name = dev_name(&ec_spi->spi->dev);
+	ec_dev->din_size = EC_MSG_PREAMBLE_COUNT +
+			   sizeof(struct ec_host_response) +
+			   sizeof(struct ec_response_get_protocol_info);
+	ec_dev->dout_size = sizeof(struct ec_host_request);
+
+	ec_spi->last_transfer_ns = ktime_get_ns();
+
+	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 of_device_id cros_ec_spi_of_match[] = {
+	{ .compatible = "google,cros-ec-spi", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, cros_ec_spi_of_match);
+
+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",
+		.of_match_table = of_match_ptr(cros_ec_spi_of_match),
+		.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)");