drivers/watchdog/ziirave_wdt.c - kernel/common - Git at Google

 /*
  * Copyright (C) 2015 Zodiac Inflight Innovations
  *
  * Author: Martyn Welch <[email protected]>
  *
  * Based on twl4030_wdt.c by Timo Kokkonen <timo.t.kokkonen at nokia.com>:
  *
  * Copyright (C) Nokia Corporation
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * 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/i2c.h>
 #include <linux/ihex.h>
 #include <linux/firmware.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/types.h>
 #include <linux/version.h>
 #include <linux/watchdog.h>

 #define ZIIRAVE_TIMEOUT_MIN	3
 #define ZIIRAVE_TIMEOUT_MAX	255

 #define ZIIRAVE_PING_VALUE	0x0

 #define ZIIRAVE_STATE_INITIAL	0x0
 #define ZIIRAVE_STATE_OFF	0x1
 #define ZIIRAVE_STATE_ON	0x2

 #define ZIIRAVE_FW_NAME		"ziirave_wdt.fw"

 static char *ziirave_reasons[] = {"power cycle", "hw watchdog", NULL, NULL,
 				  "host request", NULL, "illegal configuration",
 				  "illegal instruction", "illegal trap",
 				  "unknown"};

 #define ZIIRAVE_WDT_FIRM_VER_MAJOR	0x1
 #define ZIIRAVE_WDT_BOOT_VER_MAJOR	0x3
 #define ZIIRAVE_WDT_RESET_REASON	0x5
 #define ZIIRAVE_WDT_STATE		0x6
 #define ZIIRAVE_WDT_TIMEOUT		0x7
 #define ZIIRAVE_WDT_TIME_LEFT		0x8
 #define ZIIRAVE_WDT_PING		0x9
 #define ZIIRAVE_WDT_RESET_DURATION	0xa

 #define ZIIRAVE_FIRM_PKT_TOTAL_SIZE	20
 #define ZIIRAVE_FIRM_PKT_DATA_SIZE	16
 #define ZIIRAVE_FIRM_FLASH_MEMORY_START	0x1600
 #define ZIIRAVE_FIRM_FLASH_MEMORY_END	0x2bbf

 /* Received and ready for next Download packet. */
 #define ZIIRAVE_FIRM_DOWNLOAD_ACK	1
 /* Currently writing to flash. Retry Download status in a moment! */
 #define ZIIRAVE_FIRM_DOWNLOAD_BUSY	2

 /* Wait for ACK timeout in ms */
 #define ZIIRAVE_FIRM_WAIT_FOR_ACK_TIMEOUT	50

 /* Firmware commands */
 #define ZIIRAVE_CMD_DOWNLOAD_START		0x10
 #define ZIIRAVE_CMD_DOWNLOAD_END		0x11
 #define ZIIRAVE_CMD_DOWNLOAD_SET_READ_ADDR	0x12
 #define ZIIRAVE_CMD_DOWNLOAD_READ_BYTE		0x13
 #define ZIIRAVE_CMD_RESET_PROCESSOR		0x0b
 #define ZIIRAVE_CMD_JUMP_TO_BOOTLOADER		0x0c
 #define ZIIRAVE_CMD_DOWNLOAD_PACKET		0x0e

 struct ziirave_wdt_rev {
 	unsigned char major;
 	unsigned char minor;
 };

 struct ziirave_wdt_data {
 	struct mutex sysfs_mutex;
 	struct watchdog_device wdd;
 	struct ziirave_wdt_rev bootloader_rev;
 	struct ziirave_wdt_rev firmware_rev;
 	int reset_reason;
 };

 static int wdt_timeout;
 module_param(wdt_timeout, int, 0);
 MODULE_PARM_DESC(wdt_timeout, "Watchdog timeout in seconds");

 static int reset_duration;
 module_param(reset_duration, int, 0);
 MODULE_PARM_DESC(reset_duration,
 		 "Watchdog reset pulse duration in milliseconds");

 static bool nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started default="
 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

 static int ziirave_wdt_revision(struct i2c_client *client,
 				struct ziirave_wdt_rev *rev, u8 command)
 {
 	int ret;

 	ret = i2c_smbus_read_byte_data(client, command);
 	if (ret < 0)
 		return ret;

 	rev->major = ret;

 	ret = i2c_smbus_read_byte_data(client, command + 1);
 	if (ret < 0)
 		return ret;

 	rev->minor = ret;

 	return 0;
 }

 static int ziirave_wdt_set_state(struct watchdog_device *wdd, int state)
 {
 	struct i2c_client *client = to_i2c_client(wdd->parent);

 	return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_STATE, state);
 }

 static int ziirave_wdt_start(struct watchdog_device *wdd)
 {
 	return ziirave_wdt_set_state(wdd, ZIIRAVE_STATE_ON);
 }

 static int ziirave_wdt_stop(struct watchdog_device *wdd)
 {
 	return ziirave_wdt_set_state(wdd, ZIIRAVE_STATE_OFF);
 }

 static int ziirave_wdt_ping(struct watchdog_device *wdd)
 {
 	struct i2c_client *client = to_i2c_client(wdd->parent);

 	return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_PING,
 					 ZIIRAVE_PING_VALUE);
 }

 static int ziirave_wdt_set_timeout(struct watchdog_device *wdd,
 				   unsigned int timeout)
 {
 	struct i2c_client *client = to_i2c_client(wdd->parent);
 	int ret;

 	ret = i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_TIMEOUT, timeout);
 	if (!ret)
 		wdd->timeout = timeout;

 	return ret;
 }

 static unsigned int ziirave_wdt_get_timeleft(struct watchdog_device *wdd)
 {
 	struct i2c_client *client = to_i2c_client(wdd->parent);
 	int ret;

 	ret = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_TIME_LEFT);
 	if (ret < 0)
 		ret = 0;

 	return ret;
 }

 static int ziirave_firm_wait_for_ack(struct watchdog_device *wdd)
 {
 	struct i2c_client *client = to_i2c_client(wdd->parent);
 	int ret;
 	unsigned long timeout;

 	timeout = jiffies + msecs_to_jiffies(ZIIRAVE_FIRM_WAIT_FOR_ACK_TIMEOUT);
 	do {
 		if (time_after(jiffies, timeout))
 			return -ETIMEDOUT;

 		usleep_range(5000, 10000);

 		ret = i2c_smbus_read_byte(client);
 		if (ret < 0) {
 			dev_err(&client->dev, "Failed to read byte\n");
 			return ret;
 		}
 	} while (ret == ZIIRAVE_FIRM_DOWNLOAD_BUSY);

 	return ret == ZIIRAVE_FIRM_DOWNLOAD_ACK ? 0 : -EIO;
 }

 static int ziirave_firm_set_read_addr(struct watchdog_device *wdd, u16 addr)
 {
 	struct i2c_client *client = to_i2c_client(wdd->parent);
 	u8 address[2];

 	address[0] = addr & 0xff;
 	address[1] = (addr >> 8) & 0xff;

 	return i2c_smbus_write_block_data(client,
 					  ZIIRAVE_CMD_DOWNLOAD_SET_READ_ADDR,
 					  ARRAY_SIZE(address), address);
 }

 static int ziirave_firm_write_block_data(struct watchdog_device *wdd,
 					 u8 command, u8 length, const u8 *data,
 					 bool wait_for_ack)
 {
 	struct i2c_client *client = to_i2c_client(wdd->parent);
 	int ret;

 	ret = i2c_smbus_write_block_data(client, command, length, data);
 	if (ret) {
 		dev_err(&client->dev,
 			"Failed to send command 0x%02x: %d\n", command, ret);
 		return ret;
 	}

 	if (wait_for_ack)
 		ret = ziirave_firm_wait_for_ack(wdd);

 	return ret;
 }

 static int ziirave_firm_write_byte(struct watchdog_device *wdd, u8 command,
 				   u8 byte, bool wait_for_ack)
 {
 	return ziirave_firm_write_block_data(wdd, command, 1, &byte,
 					     wait_for_ack);
 }

 /*
  * ziirave_firm_write_pkt() - Build and write a firmware packet
  *
  * A packet to send to the firmware is composed by following bytes:
  *     Length | Addr0 | Addr1 | Data0 .. Data15 | Checksum |
  * Where,
  *     Length: A data byte containing the length of the data.
  *     Addr0: Low byte of the address.
  *     Addr1: High byte of the address.
  *     Data0 .. Data15: Array of 16 bytes of data.
  *     Checksum: Checksum byte to verify data integrity.
  */
 static int ziirave_firm_write_pkt(struct watchdog_device *wdd,
 				  const struct ihex_binrec *rec)
 {
 	struct i2c_client *client = to_i2c_client(wdd->parent);
 	u8 i, checksum = 0, packet[ZIIRAVE_FIRM_PKT_TOTAL_SIZE];
 	int ret;
 	u16 addr;

 	memset(packet, 0, ARRAY_SIZE(packet));

 	/* Packet length */
 	packet[0] = (u8)be16_to_cpu(rec->len);
 	/* Packet address */
 	addr = (be32_to_cpu(rec->addr) & 0xffff) >> 1;
 	packet[1] = addr & 0xff;
 	packet[2] = (addr & 0xff00) >> 8;

 	/* Packet data */
 	if (be16_to_cpu(rec->len) > ZIIRAVE_FIRM_PKT_DATA_SIZE)
 		return -EMSGSIZE;
 	memcpy(packet + 3, rec->data, be16_to_cpu(rec->len));

 	/* Packet checksum */
 	for (i = 0; i < ZIIRAVE_FIRM_PKT_TOTAL_SIZE - 1; i++)
 		checksum += packet[i];
 	packet[ZIIRAVE_FIRM_PKT_TOTAL_SIZE - 1] = checksum;

 	ret = ziirave_firm_write_block_data(wdd, ZIIRAVE_CMD_DOWNLOAD_PACKET,
 					    ARRAY_SIZE(packet), packet, true);
 	if (ret)
 		dev_err(&client->dev,
 		      "Failed to write firmware packet at address 0x%04x: %d\n",
 		      addr, ret);

 	return ret;
 }

 static int ziirave_firm_verify(struct watchdog_device *wdd,
 			       const struct firmware *fw)
 {
 	struct i2c_client *client = to_i2c_client(wdd->parent);
 	const struct ihex_binrec *rec;
 	int i, ret;
 	u8 data[ZIIRAVE_FIRM_PKT_DATA_SIZE];
 	u16 addr;

 	for (rec = (void *)fw->data; rec; rec = ihex_next_binrec(rec)) {
 		/* Zero length marks end of records */
 		if (!be16_to_cpu(rec->len))
 			break;

 		addr = (be32_to_cpu(rec->addr) & 0xffff) >> 1;
 		if (addr < ZIIRAVE_FIRM_FLASH_MEMORY_START ||
 		    addr > ZIIRAVE_FIRM_FLASH_MEMORY_END)
 			continue;

 		ret = ziirave_firm_set_read_addr(wdd, addr);
 		if (ret) {
 			dev_err(&client->dev,
 				"Failed to send SET_READ_ADDR command: %d\n",
 				ret);
 			return ret;
 		}

 		for (i = 0; i < ARRAY_SIZE(data); i++) {
 			ret = i2c_smbus_read_byte_data(client,
 						ZIIRAVE_CMD_DOWNLOAD_READ_BYTE);
 			if (ret < 0) {
 				dev_err(&client->dev,
 					"Failed to READ DATA: %d\n", ret);
 				return ret;
 			}
 			data[i] = ret;
 		}

 		if (memcmp(data, rec->data, be16_to_cpu(rec->len))) {
 			dev_err(&client->dev,
 				"Firmware mismatch at address 0x%04x\n", addr);
 			return -EINVAL;
 		}
 	}

 	return 0;
 }

 static int ziirave_firm_upload(struct watchdog_device *wdd,
 			       const struct firmware *fw)
 {
 	struct i2c_client *client = to_i2c_client(wdd->parent);
 	int ret, words_till_page_break;
 	const struct ihex_binrec *rec;
 	struct ihex_binrec *rec_new;

 	ret = ziirave_firm_write_byte(wdd, ZIIRAVE_CMD_JUMP_TO_BOOTLOADER, 1,
 				      false);
 	if (ret)
 		return ret;

 	msleep(500);

 	ret = ziirave_firm_write_byte(wdd, ZIIRAVE_CMD_DOWNLOAD_START, 1, true);
 	if (ret)
 		return ret;

 	msleep(500);

 	for (rec = (void *)fw->data; rec; rec = ihex_next_binrec(rec)) {
 		/* Zero length marks end of records */
 		if (!be16_to_cpu(rec->len))
 			break;

 		/* Check max data size */
 		if (be16_to_cpu(rec->len) > ZIIRAVE_FIRM_PKT_DATA_SIZE) {
 			dev_err(&client->dev, "Firmware packet too long (%d)\n",
 				be16_to_cpu(rec->len));
 			return -EMSGSIZE;
 		}

 		/* Calculate words till page break */
 		words_till_page_break = (64 - ((be32_to_cpu(rec->addr) >> 1) &
 					 0x3f));
 		if ((be16_to_cpu(rec->len) >> 1) > words_till_page_break) {
 			/*
 			 * Data in passes page boundary, so we need to split in
 			 * two blocks of data. Create a packet with the first
 			 * block of data.
 			 */
 			rec_new = kzalloc(sizeof(struct ihex_binrec) +
 					  (words_till_page_break << 1),
 					  GFP_KERNEL);
 			if (!rec_new)
 				return -ENOMEM;

 			rec_new->len = cpu_to_be16(words_till_page_break << 1);
 			rec_new->addr = rec->addr;
 			memcpy(rec_new->data, rec->data,
 			       be16_to_cpu(rec_new->len));

 			ret = ziirave_firm_write_pkt(wdd, rec_new);
 			kfree(rec_new);
 			if (ret)
 				return ret;

 			/* Create a packet with the second block of data */
 			rec_new = kzalloc(sizeof(struct ihex_binrec) +
 					  be16_to_cpu(rec->len) -
 					  (words_till_page_break << 1),
 					  GFP_KERNEL);
 			if (!rec_new)
 				return -ENOMEM;

 			/* Remaining bytes */
 			rec_new->len = rec->len -
 				       cpu_to_be16(words_till_page_break << 1);

 			rec_new->addr = cpu_to_be32(be32_to_cpu(rec->addr) +
 					(words_till_page_break << 1));

 			memcpy(rec_new->data,
 			       rec->data + (words_till_page_break << 1),
 			       be16_to_cpu(rec_new->len));

 			ret = ziirave_firm_write_pkt(wdd, rec_new);
 			kfree(rec_new);
 			if (ret)
 				return ret;
 		} else {
 			ret = ziirave_firm_write_pkt(wdd, rec);
 			if (ret)
 				return ret;
 		}
 	}

 	/* For end of download, the length field will be set to 0 */
 	rec_new = kzalloc(sizeof(struct ihex_binrec) + 1, GFP_KERNEL);
 	if (!rec_new)
 		return -ENOMEM;

 	ret = ziirave_firm_write_pkt(wdd, rec_new);
 	kfree(rec_new);
 	if (ret) {
 		dev_err(&client->dev, "Failed to send EMPTY packet: %d\n", ret);
 		return ret;
 	}

 	/* This sleep seems to be required */
 	msleep(20);

 	/* Start firmware verification */
 	ret = ziirave_firm_verify(wdd, fw);
 	if (ret) {
 		dev_err(&client->dev,
 			"Failed to verify firmware: %d\n", ret);
 		return ret;
 	}

 	/* End download operation */
 	ret = ziirave_firm_write_byte(wdd, ZIIRAVE_CMD_DOWNLOAD_END, 1, false);
 	if (ret)
 		return ret;

 	/* Reset the processor */
 	ret = ziirave_firm_write_byte(wdd, ZIIRAVE_CMD_RESET_PROCESSOR, 1,
 				      false);
 	if (ret)
 		return ret;

 	msleep(500);

 	return 0;
 }

 static const struct watchdog_info ziirave_wdt_info = {
 	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 	.identity = "Zodiac RAVE Watchdog",
 };

 static const struct watchdog_ops ziirave_wdt_ops = {
 	.owner		= THIS_MODULE,
 	.start		= ziirave_wdt_start,
 	.stop		= ziirave_wdt_stop,
 	.ping		= ziirave_wdt_ping,
 	.set_timeout	= ziirave_wdt_set_timeout,
 	.get_timeleft	= ziirave_wdt_get_timeleft,
 };

 static ssize_t ziirave_wdt_sysfs_show_firm(struct device *dev,
 					   struct device_attribute *attr,
 					   char *buf)
 {
 	struct i2c_client *client = to_i2c_client(dev->parent);
 	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
 	int ret;

 	ret = mutex_lock_interruptible(&w_priv->sysfs_mutex);
 	if (ret)
 		return ret;

 	ret = sprintf(buf, "02.%02u.%02u", w_priv->firmware_rev.major,
 		      w_priv->firmware_rev.minor);

 	mutex_unlock(&w_priv->sysfs_mutex);

 	return ret;
 }

 static DEVICE_ATTR(firmware_version, S_IRUGO, ziirave_wdt_sysfs_show_firm,
 		   NULL);

 static ssize_t ziirave_wdt_sysfs_show_boot(struct device *dev,
 					   struct device_attribute *attr,
 					   char *buf)
 {
 	struct i2c_client *client = to_i2c_client(dev->parent);
 	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
 	int ret;

 	ret = mutex_lock_interruptible(&w_priv->sysfs_mutex);
 	if (ret)
 		return ret;

 	ret = sprintf(buf, "01.%02u.%02u", w_priv->bootloader_rev.major,
 		      w_priv->bootloader_rev.minor);

 	mutex_unlock(&w_priv->sysfs_mutex);

 	return ret;
 }

 static DEVICE_ATTR(bootloader_version, S_IRUGO, ziirave_wdt_sysfs_show_boot,
 		   NULL);

 static ssize_t ziirave_wdt_sysfs_show_reason(struct device *dev,
 					     struct device_attribute *attr,
 					     char *buf)
 {
 	struct i2c_client *client = to_i2c_client(dev->parent);
 	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
 	int ret;

 	ret = mutex_lock_interruptible(&w_priv->sysfs_mutex);
 	if (ret)
 		return ret;

 	ret = sprintf(buf, "%s", ziirave_reasons[w_priv->reset_reason]);

 	mutex_unlock(&w_priv->sysfs_mutex);

 	return ret;
 }

 static DEVICE_ATTR(reset_reason, S_IRUGO, ziirave_wdt_sysfs_show_reason,
 		   NULL);

 static ssize_t ziirave_wdt_sysfs_store_firm(struct device *dev,
 					    struct device_attribute *attr,
 					    const char *buf, size_t count)
 {
 	struct i2c_client *client = to_i2c_client(dev->parent);
 	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
 	const struct firmware *fw;
 	int err;

 	err = request_ihex_firmware(&fw, ZIIRAVE_FW_NAME, dev);
 	if (err) {
 		dev_err(&client->dev, "Failed to request ihex firmware\n");
 		return err;
 	}

 	err = mutex_lock_interruptible(&w_priv->sysfs_mutex);
 	if (err)
 		goto release_firmware;

 	err = ziirave_firm_upload(&w_priv->wdd, fw);
 	if (err) {
 		dev_err(&client->dev, "The firmware update failed: %d\n", err);
 		goto unlock_mutex;
 	}

 	/* Update firmware version */
 	err = ziirave_wdt_revision(client, &w_priv->firmware_rev,
 				   ZIIRAVE_WDT_FIRM_VER_MAJOR);
 	if (err) {
 		dev_err(&client->dev, "Failed to read firmware version: %d\n",
 			err);
 		goto unlock_mutex;
 	}

 	dev_info(&client->dev, "Firmware updated to version 02.%02u.%02u\n",
 		 w_priv->firmware_rev.major, w_priv->firmware_rev.minor);

 	/* Restore the watchdog timeout */
 	err = ziirave_wdt_set_timeout(&w_priv->wdd, w_priv->wdd.timeout);
 	if (err)
 		dev_err(&client->dev, "Failed to set timeout: %d\n", err);

 unlock_mutex:
 	mutex_unlock(&w_priv->sysfs_mutex);

 release_firmware:
 	release_firmware(fw);

 	return err ? err : count;
 }

 static DEVICE_ATTR(update_firmware, S_IWUSR, NULL,
 		   ziirave_wdt_sysfs_store_firm);

 static struct attribute *ziirave_wdt_attrs[] = {
 	&dev_attr_firmware_version.attr,
 	&dev_attr_bootloader_version.attr,
 	&dev_attr_reset_reason.attr,
 	&dev_attr_update_firmware.attr,
 	NULL
 };
 ATTRIBUTE_GROUPS(ziirave_wdt);

 static int ziirave_wdt_init_duration(struct i2c_client *client)
 {
 	int ret;

 	if (!reset_duration) {
 		/* See if the reset pulse duration is provided in an of_node */
 		if (!client->dev.of_node)
 			ret = -ENODEV;
 		else
 			ret = of_property_read_u32(client->dev.of_node,
 						   "reset-duration-ms",
 						   &reset_duration);
 		if (ret) {
 			dev_info(&client->dev,
 				 "Unable to set reset pulse duration, using default\n");
 			return 0;
 		}
 	}

 	if (reset_duration < 1 || reset_duration > 255)
 		return -EINVAL;

 	dev_info(&client->dev, "Setting reset duration to %dms",
 		 reset_duration);

 	return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_RESET_DURATION,
 					 reset_duration);
 }

 static int ziirave_wdt_probe(struct i2c_client *client,
 			     const struct i2c_device_id *id)
 {
 	int ret;
 	struct ziirave_wdt_data *w_priv;
 	int val;

 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 		return -ENODEV;

 	w_priv = devm_kzalloc(&client->dev, sizeof(*w_priv), GFP_KERNEL);
 	if (!w_priv)
 		return -ENOMEM;

 	mutex_init(&w_priv->sysfs_mutex);

 	w_priv->wdd.info = &ziirave_wdt_info;
 	w_priv->wdd.ops = &ziirave_wdt_ops;
 	w_priv->wdd.min_timeout = ZIIRAVE_TIMEOUT_MIN;
 	w_priv->wdd.max_timeout = ZIIRAVE_TIMEOUT_MAX;
 	w_priv->wdd.parent = &client->dev;
 	w_priv->wdd.groups = ziirave_wdt_groups;

 	ret = watchdog_init_timeout(&w_priv->wdd, wdt_timeout, &client->dev);
 	if (ret) {
 		dev_info(&client->dev,
 			 "Unable to select timeout value, using default\n");
 	}

 	/*
 	 * The default value set in the watchdog should be perfectly valid, so
 	 * pass that in if we haven't provided one via the module parameter or
 	 * of property.
 	 */
 	if (w_priv->wdd.timeout == 0) {
 		val = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_TIMEOUT);
 		if (val < 0)
 			return val;

 		if (val < ZIIRAVE_TIMEOUT_MIN)
 			return -ENODEV;

 		w_priv->wdd.timeout = val;
 	} else {
 		ret = ziirave_wdt_set_timeout(&w_priv->wdd,
 					      w_priv->wdd.timeout);
 		if (ret)
 			return ret;

 		dev_info(&client->dev, "Timeout set to %ds.",
 			 w_priv->wdd.timeout);
 	}

 	watchdog_set_nowayout(&w_priv->wdd, nowayout);

 	i2c_set_clientdata(client, w_priv);

 	/* If in unconfigured state, set to stopped */
 	val = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_STATE);
 	if (val < 0)
 		return val;

 	if (val == ZIIRAVE_STATE_INITIAL)
 		ziirave_wdt_stop(&w_priv->wdd);

 	ret = ziirave_wdt_init_duration(client);
 	if (ret)
 		return ret;

 	ret = ziirave_wdt_revision(client, &w_priv->firmware_rev,
 				   ZIIRAVE_WDT_FIRM_VER_MAJOR);
 	if (ret)
 		return ret;

 	ret = ziirave_wdt_revision(client, &w_priv->bootloader_rev,
 				   ZIIRAVE_WDT_BOOT_VER_MAJOR);
 	if (ret)
 		return ret;

 	w_priv->reset_reason = i2c_smbus_read_byte_data(client,
 						ZIIRAVE_WDT_RESET_REASON);
 	if (w_priv->reset_reason < 0)
 		return w_priv->reset_reason;

 	if (w_priv->reset_reason >= ARRAY_SIZE(ziirave_reasons) ||
 	    !ziirave_reasons[w_priv->reset_reason])
 		return -ENODEV;

 	ret = watchdog_register_device(&w_priv->wdd);

 	return ret;
 }

 static int ziirave_wdt_remove(struct i2c_client *client)
 {
 	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);

 	watchdog_unregister_device(&w_priv->wdd);

 	return 0;
 }

 static struct i2c_device_id ziirave_wdt_id[] = {
 	{ "rave-wdt", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, ziirave_wdt_id);

 static const struct of_device_id zrv_wdt_of_match[] = {
 	{ .compatible = "zii,rave-wdt", },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, zrv_wdt_of_match);

 static struct i2c_driver ziirave_wdt_driver = {
 	.driver = {
 		.name = "ziirave_wdt",
 		.of_match_table = zrv_wdt_of_match,
 	},
 	.probe = ziirave_wdt_probe,
 	.remove = ziirave_wdt_remove,
 	.id_table = ziirave_wdt_id,
 };

 module_i2c_driver(ziirave_wdt_driver);

 MODULE_AUTHOR("Martyn Welch <[email protected]");
 MODULE_DESCRIPTION("Zodiac Aerospace RAVE Switch Watchdog Processor Driver");
 MODULE_LICENSE("GPL");
	/*
	* Copyright (C) 2015 Zodiac Inflight Innovations
	*
	* Author: Martyn Welch <[email protected]>
	*
	* Based on twl4030_wdt.c by Timo Kokkonen <timo.t.kokkonen at nokia.com>:
	*
	* Copyright (C) Nokia Corporation
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* 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/i2c.h>
	#include <linux/ihex.h>
	#include <linux/firmware.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/sysfs.h>
	#include <linux/types.h>
	#include <linux/version.h>
	#include <linux/watchdog.h>

	#define ZIIRAVE_TIMEOUT_MIN 3
	#define ZIIRAVE_TIMEOUT_MAX 255

	#define ZIIRAVE_PING_VALUE 0x0

	#define ZIIRAVE_STATE_INITIAL 0x0
	#define ZIIRAVE_STATE_OFF 0x1
	#define ZIIRAVE_STATE_ON 0x2

	#define ZIIRAVE_FW_NAME "ziirave_wdt.fw"

	static char *ziirave_reasons[] = {"power cycle", "hw watchdog", NULL, NULL,
	"host request", NULL, "illegal configuration",
	"illegal instruction", "illegal trap",
	"unknown"};

	#define ZIIRAVE_WDT_FIRM_VER_MAJOR 0x1
	#define ZIIRAVE_WDT_BOOT_VER_MAJOR 0x3
	#define ZIIRAVE_WDT_RESET_REASON 0x5
	#define ZIIRAVE_WDT_STATE 0x6
	#define ZIIRAVE_WDT_TIMEOUT 0x7
	#define ZIIRAVE_WDT_TIME_LEFT 0x8
	#define ZIIRAVE_WDT_PING 0x9
	#define ZIIRAVE_WDT_RESET_DURATION 0xa

	#define ZIIRAVE_FIRM_PKT_TOTAL_SIZE 20
	#define ZIIRAVE_FIRM_PKT_DATA_SIZE 16
	#define ZIIRAVE_FIRM_FLASH_MEMORY_START 0x1600
	#define ZIIRAVE_FIRM_FLASH_MEMORY_END 0x2bbf

	/* Received and ready for next Download packet. */
	#define ZIIRAVE_FIRM_DOWNLOAD_ACK 1
	/* Currently writing to flash. Retry Download status in a moment! */
	#define ZIIRAVE_FIRM_DOWNLOAD_BUSY 2

	/* Wait for ACK timeout in ms */
	#define ZIIRAVE_FIRM_WAIT_FOR_ACK_TIMEOUT 50

	/* Firmware commands */
	#define ZIIRAVE_CMD_DOWNLOAD_START 0x10
	#define ZIIRAVE_CMD_DOWNLOAD_END 0x11
	#define ZIIRAVE_CMD_DOWNLOAD_SET_READ_ADDR 0x12
	#define ZIIRAVE_CMD_DOWNLOAD_READ_BYTE 0x13
	#define ZIIRAVE_CMD_RESET_PROCESSOR 0x0b
	#define ZIIRAVE_CMD_JUMP_TO_BOOTLOADER 0x0c
	#define ZIIRAVE_CMD_DOWNLOAD_PACKET 0x0e

	struct ziirave_wdt_rev {
	unsigned char major;
	unsigned char minor;
	};

	struct ziirave_wdt_data {
	struct mutex sysfs_mutex;
	struct watchdog_device wdd;
	struct ziirave_wdt_rev bootloader_rev;
	struct ziirave_wdt_rev firmware_rev;
	int reset_reason;
	};

	static int wdt_timeout;
	module_param(wdt_timeout, int, 0);
	MODULE_PARM_DESC(wdt_timeout, "Watchdog timeout in seconds");

	static int reset_duration;
	module_param(reset_duration, int, 0);
	MODULE_PARM_DESC(reset_duration,
	"Watchdog reset pulse duration in milliseconds");

	static bool nowayout = WATCHDOG_NOWAYOUT;
	module_param(nowayout, bool, 0);
	MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started default="
	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

	static int ziirave_wdt_revision(struct i2c_client *client,
	struct ziirave_wdt_rev *rev, u8 command)
	{
	int ret;

	ret = i2c_smbus_read_byte_data(client, command);
	if (ret < 0)
	return ret;

	rev->major = ret;

	ret = i2c_smbus_read_byte_data(client, command + 1);
	if (ret < 0)
	return ret;

	rev->minor = ret;

	return 0;
	}

	static int ziirave_wdt_set_state(struct watchdog_device *wdd, int state)
	{
	struct i2c_client *client = to_i2c_client(wdd->parent);

	return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_STATE, state);
	}

	static int ziirave_wdt_start(struct watchdog_device *wdd)
	{
	return ziirave_wdt_set_state(wdd, ZIIRAVE_STATE_ON);
	}

	static int ziirave_wdt_stop(struct watchdog_device *wdd)
	{
	return ziirave_wdt_set_state(wdd, ZIIRAVE_STATE_OFF);
	}

	static int ziirave_wdt_ping(struct watchdog_device *wdd)
	{
	struct i2c_client *client = to_i2c_client(wdd->parent);

	return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_PING,
	ZIIRAVE_PING_VALUE);
	}

	static int ziirave_wdt_set_timeout(struct watchdog_device *wdd,
	unsigned int timeout)
	{
	struct i2c_client *client = to_i2c_client(wdd->parent);
	int ret;

	ret = i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_TIMEOUT, timeout);
	if (!ret)
	wdd->timeout = timeout;

	return ret;
	}

	static unsigned int ziirave_wdt_get_timeleft(struct watchdog_device *wdd)
	{
	struct i2c_client *client = to_i2c_client(wdd->parent);
	int ret;

	ret = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_TIME_LEFT);
	if (ret < 0)
	ret = 0;

	return ret;
	}

	static int ziirave_firm_wait_for_ack(struct watchdog_device *wdd)
	{
	struct i2c_client *client = to_i2c_client(wdd->parent);
	int ret;
	unsigned long timeout;

	timeout = jiffies + msecs_to_jiffies(ZIIRAVE_FIRM_WAIT_FOR_ACK_TIMEOUT);
	do {
	if (time_after(jiffies, timeout))
	return -ETIMEDOUT;

	usleep_range(5000, 10000);

	ret = i2c_smbus_read_byte(client);
	if (ret < 0) {
	dev_err(&client->dev, "Failed to read byte\n");
	return ret;
	}
	} while (ret == ZIIRAVE_FIRM_DOWNLOAD_BUSY);

	return ret == ZIIRAVE_FIRM_DOWNLOAD_ACK ? 0 : -EIO;
	}

	static int ziirave_firm_set_read_addr(struct watchdog_device *wdd, u16 addr)
	{
	struct i2c_client *client = to_i2c_client(wdd->parent);
	u8 address[2];

	address[0] = addr & 0xff;
	address[1] = (addr >> 8) & 0xff;

	return i2c_smbus_write_block_data(client,
	ZIIRAVE_CMD_DOWNLOAD_SET_READ_ADDR,
	ARRAY_SIZE(address), address);
	}

	static int ziirave_firm_write_block_data(struct watchdog_device *wdd,
	u8 command, u8 length, const u8 *data,
	bool wait_for_ack)
	{
	struct i2c_client *client = to_i2c_client(wdd->parent);
	int ret;

	ret = i2c_smbus_write_block_data(client, command, length, data);
	if (ret) {
	dev_err(&client->dev,
	"Failed to send command 0x%02x: %d\n", command, ret);
	return ret;
	}

	if (wait_for_ack)
	ret = ziirave_firm_wait_for_ack(wdd);

	return ret;
	}

	static int ziirave_firm_write_byte(struct watchdog_device *wdd, u8 command,
	u8 byte, bool wait_for_ack)
	{
	return ziirave_firm_write_block_data(wdd, command, 1, &byte,
	wait_for_ack);
	}

	/*
	* ziirave_firm_write_pkt() - Build and write a firmware packet
	*
	* A packet to send to the firmware is composed by following bytes:
	* Length \| Addr0 \| Addr1 \| Data0 .. Data15 \| Checksum \|
	* Where,
	* Length: A data byte containing the length of the data.
	* Addr0: Low byte of the address.
	* Addr1: High byte of the address.
	* Data0 .. Data15: Array of 16 bytes of data.
	* Checksum: Checksum byte to verify data integrity.
	*/
	static int ziirave_firm_write_pkt(struct watchdog_device *wdd,
	const struct ihex_binrec *rec)
	{
	struct i2c_client *client = to_i2c_client(wdd->parent);
	u8 i, checksum = 0, packet[ZIIRAVE_FIRM_PKT_TOTAL_SIZE];
	int ret;
	u16 addr;

	memset(packet, 0, ARRAY_SIZE(packet));

	/* Packet length */
	packet[0] = (u8)be16_to_cpu(rec->len);
	/* Packet address */
	addr = (be32_to_cpu(rec->addr) & 0xffff) >> 1;
	packet[1] = addr & 0xff;
	packet[2] = (addr & 0xff00) >> 8;

	/* Packet data */
	if (be16_to_cpu(rec->len) > ZIIRAVE_FIRM_PKT_DATA_SIZE)
	return -EMSGSIZE;
	memcpy(packet + 3, rec->data, be16_to_cpu(rec->len));

	/* Packet checksum */
	for (i = 0; i < ZIIRAVE_FIRM_PKT_TOTAL_SIZE - 1; i++)
	checksum += packet[i];
	packet[ZIIRAVE_FIRM_PKT_TOTAL_SIZE - 1] = checksum;

	ret = ziirave_firm_write_block_data(wdd, ZIIRAVE_CMD_DOWNLOAD_PACKET,
	ARRAY_SIZE(packet), packet, true);
	if (ret)
	dev_err(&client->dev,
	"Failed to write firmware packet at address 0x%04x: %d\n",
	addr, ret);

	return ret;
	}

	static int ziirave_firm_verify(struct watchdog_device *wdd,
	const struct firmware *fw)
	{
	struct i2c_client *client = to_i2c_client(wdd->parent);
	const struct ihex_binrec *rec;
	int i, ret;
	u8 data[ZIIRAVE_FIRM_PKT_DATA_SIZE];
	u16 addr;

	for (rec = (void *)fw->data; rec; rec = ihex_next_binrec(rec)) {
	/* Zero length marks end of records */
	if (!be16_to_cpu(rec->len))
	break;

	addr = (be32_to_cpu(rec->addr) & 0xffff) >> 1;
	if (addr < ZIIRAVE_FIRM_FLASH_MEMORY_START \|\|
	addr > ZIIRAVE_FIRM_FLASH_MEMORY_END)
	continue;

	ret = ziirave_firm_set_read_addr(wdd, addr);
	if (ret) {
	dev_err(&client->dev,
	"Failed to send SET_READ_ADDR command: %d\n",
	ret);
	return ret;
	}

	for (i = 0; i < ARRAY_SIZE(data); i++) {
	ret = i2c_smbus_read_byte_data(client,
	ZIIRAVE_CMD_DOWNLOAD_READ_BYTE);
	if (ret < 0) {
	dev_err(&client->dev,
	"Failed to READ DATA: %d\n", ret);
	return ret;
	}
	data[i] = ret;
	}

	if (memcmp(data, rec->data, be16_to_cpu(rec->len))) {
	dev_err(&client->dev,
	"Firmware mismatch at address 0x%04x\n", addr);
	return -EINVAL;
	}
	}

	return 0;
	}

	static int ziirave_firm_upload(struct watchdog_device *wdd,
	const struct firmware *fw)
	{
	struct i2c_client *client = to_i2c_client(wdd->parent);
	int ret, words_till_page_break;
	const struct ihex_binrec *rec;
	struct ihex_binrec *rec_new;

	ret = ziirave_firm_write_byte(wdd, ZIIRAVE_CMD_JUMP_TO_BOOTLOADER, 1,
	false);
	if (ret)
	return ret;

	msleep(500);

	ret = ziirave_firm_write_byte(wdd, ZIIRAVE_CMD_DOWNLOAD_START, 1, true);
	if (ret)
	return ret;

	msleep(500);

	for (rec = (void *)fw->data; rec; rec = ihex_next_binrec(rec)) {
	/* Zero length marks end of records */
	if (!be16_to_cpu(rec->len))
	break;

	/* Check max data size */
	if (be16_to_cpu(rec->len) > ZIIRAVE_FIRM_PKT_DATA_SIZE) {
	dev_err(&client->dev, "Firmware packet too long (%d)\n",
	be16_to_cpu(rec->len));
	return -EMSGSIZE;
	}

	/* Calculate words till page break */
	words_till_page_break = (64 - ((be32_to_cpu(rec->addr) >> 1) &
	0x3f));
	if ((be16_to_cpu(rec->len) >> 1) > words_till_page_break) {
	/*
	* Data in passes page boundary, so we need to split in
	* two blocks of data. Create a packet with the first
	* block of data.
	*/
	rec_new = kzalloc(sizeof(struct ihex_binrec) +
	(words_till_page_break << 1),
	GFP_KERNEL);
	if (!rec_new)
	return -ENOMEM;

	rec_new->len = cpu_to_be16(words_till_page_break << 1);
	rec_new->addr = rec->addr;
	memcpy(rec_new->data, rec->data,
	be16_to_cpu(rec_new->len));

	ret = ziirave_firm_write_pkt(wdd, rec_new);
	kfree(rec_new);
	if (ret)
	return ret;

	/* Create a packet with the second block of data */
	rec_new = kzalloc(sizeof(struct ihex_binrec) +
	be16_to_cpu(rec->len) -
	(words_till_page_break << 1),
	GFP_KERNEL);
	if (!rec_new)
	return -ENOMEM;

	/* Remaining bytes */
	rec_new->len = rec->len -
	cpu_to_be16(words_till_page_break << 1);

	rec_new->addr = cpu_to_be32(be32_to_cpu(rec->addr) +
	(words_till_page_break << 1));

	memcpy(rec_new->data,
	rec->data + (words_till_page_break << 1),
	be16_to_cpu(rec_new->len));

	ret = ziirave_firm_write_pkt(wdd, rec_new);
	kfree(rec_new);
	if (ret)
	return ret;
	} else {
	ret = ziirave_firm_write_pkt(wdd, rec);
	if (ret)
	return ret;
	}
	}

	/* For end of download, the length field will be set to 0 */
	rec_new = kzalloc(sizeof(struct ihex_binrec) + 1, GFP_KERNEL);
	if (!rec_new)
	return -ENOMEM;

	ret = ziirave_firm_write_pkt(wdd, rec_new);
	kfree(rec_new);
	if (ret) {
	dev_err(&client->dev, "Failed to send EMPTY packet: %d\n", ret);
	return ret;
	}

	/* This sleep seems to be required */
	msleep(20);

	/* Start firmware verification */
	ret = ziirave_firm_verify(wdd, fw);
	if (ret) {
	dev_err(&client->dev,
	"Failed to verify firmware: %d\n", ret);
	return ret;
	}

	/* End download operation */
	ret = ziirave_firm_write_byte(wdd, ZIIRAVE_CMD_DOWNLOAD_END, 1, false);
	if (ret)
	return ret;

	/* Reset the processor */
	ret = ziirave_firm_write_byte(wdd, ZIIRAVE_CMD_RESET_PROCESSOR, 1,
	false);
	if (ret)
	return ret;

	msleep(500);

	return 0;
	}

	static const struct watchdog_info ziirave_wdt_info = {
	.options = WDIOF_SETTIMEOUT \| WDIOF_MAGICCLOSE \| WDIOF_KEEPALIVEPING,
	.identity = "Zodiac RAVE Watchdog",
	};

	static const struct watchdog_ops ziirave_wdt_ops = {
	.owner = THIS_MODULE,
	.start = ziirave_wdt_start,
	.stop = ziirave_wdt_stop,
	.ping = ziirave_wdt_ping,
	.set_timeout = ziirave_wdt_set_timeout,
	.get_timeleft = ziirave_wdt_get_timeleft,
	};

	static ssize_t ziirave_wdt_sysfs_show_firm(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	struct i2c_client *client = to_i2c_client(dev->parent);
	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
	int ret;

	ret = mutex_lock_interruptible(&w_priv->sysfs_mutex);
	if (ret)
	return ret;

	ret = sprintf(buf, "02.%02u.%02u", w_priv->firmware_rev.major,
	w_priv->firmware_rev.minor);

	mutex_unlock(&w_priv->sysfs_mutex);

	return ret;
	}

	static DEVICE_ATTR(firmware_version, S_IRUGO, ziirave_wdt_sysfs_show_firm,
	NULL);

	static ssize_t ziirave_wdt_sysfs_show_boot(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	struct i2c_client *client = to_i2c_client(dev->parent);
	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
	int ret;

	ret = mutex_lock_interruptible(&w_priv->sysfs_mutex);
	if (ret)
	return ret;

	ret = sprintf(buf, "01.%02u.%02u", w_priv->bootloader_rev.major,
	w_priv->bootloader_rev.minor);

	mutex_unlock(&w_priv->sysfs_mutex);

	return ret;
	}

	static DEVICE_ATTR(bootloader_version, S_IRUGO, ziirave_wdt_sysfs_show_boot,
	NULL);

	static ssize_t ziirave_wdt_sysfs_show_reason(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	struct i2c_client *client = to_i2c_client(dev->parent);
	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
	int ret;

	ret = mutex_lock_interruptible(&w_priv->sysfs_mutex);
	if (ret)
	return ret;

	ret = sprintf(buf, "%s", ziirave_reasons[w_priv->reset_reason]);

	mutex_unlock(&w_priv->sysfs_mutex);

	return ret;
	}

	static DEVICE_ATTR(reset_reason, S_IRUGO, ziirave_wdt_sysfs_show_reason,
	NULL);

	static ssize_t ziirave_wdt_sysfs_store_firm(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t count)
	{
	struct i2c_client *client = to_i2c_client(dev->parent);
	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
	const struct firmware *fw;
	int err;

	err = request_ihex_firmware(&fw, ZIIRAVE_FW_NAME, dev);
	if (err) {
	dev_err(&client->dev, "Failed to request ihex firmware\n");
	return err;
	}

	err = mutex_lock_interruptible(&w_priv->sysfs_mutex);
	if (err)
	goto release_firmware;

	err = ziirave_firm_upload(&w_priv->wdd, fw);
	if (err) {
	dev_err(&client->dev, "The firmware update failed: %d\n", err);
	goto unlock_mutex;
	}

	/* Update firmware version */
	err = ziirave_wdt_revision(client, &w_priv->firmware_rev,
	ZIIRAVE_WDT_FIRM_VER_MAJOR);
	if (err) {
	dev_err(&client->dev, "Failed to read firmware version: %d\n",
	err);
	goto unlock_mutex;
	}

	dev_info(&client->dev, "Firmware updated to version 02.%02u.%02u\n",
	w_priv->firmware_rev.major, w_priv->firmware_rev.minor);

	/* Restore the watchdog timeout */
	err = ziirave_wdt_set_timeout(&w_priv->wdd, w_priv->wdd.timeout);
	if (err)
	dev_err(&client->dev, "Failed to set timeout: %d\n", err);

	unlock_mutex:
	mutex_unlock(&w_priv->sysfs_mutex);

	release_firmware:
	release_firmware(fw);

	return err ? err : count;
	}

	static DEVICE_ATTR(update_firmware, S_IWUSR, NULL,
	ziirave_wdt_sysfs_store_firm);

	static struct attribute *ziirave_wdt_attrs[] = {
	&dev_attr_firmware_version.attr,
	&dev_attr_bootloader_version.attr,
	&dev_attr_reset_reason.attr,
	&dev_attr_update_firmware.attr,
	NULL
	};
	ATTRIBUTE_GROUPS(ziirave_wdt);

	static int ziirave_wdt_init_duration(struct i2c_client *client)
	{
	int ret;

	if (!reset_duration) {
	/* See if the reset pulse duration is provided in an of_node */
	if (!client->dev.of_node)
	ret = -ENODEV;
	else
	ret = of_property_read_u32(client->dev.of_node,
	"reset-duration-ms",
	&reset_duration);
	if (ret) {
	dev_info(&client->dev,
	"Unable to set reset pulse duration, using default\n");
	return 0;
	}
	}

	if (reset_duration < 1 \|\| reset_duration > 255)
	return -EINVAL;

	dev_info(&client->dev, "Setting reset duration to %dms",
	reset_duration);

	return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_RESET_DURATION,
	reset_duration);
	}

	static int ziirave_wdt_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	int ret;
	struct ziirave_wdt_data *w_priv;
	int val;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
	return -ENODEV;

	w_priv = devm_kzalloc(&client->dev, sizeof(*w_priv), GFP_KERNEL);
	if (!w_priv)
	return -ENOMEM;

	mutex_init(&w_priv->sysfs_mutex);

	w_priv->wdd.info = &ziirave_wdt_info;
	w_priv->wdd.ops = &ziirave_wdt_ops;
	w_priv->wdd.min_timeout = ZIIRAVE_TIMEOUT_MIN;
	w_priv->wdd.max_timeout = ZIIRAVE_TIMEOUT_MAX;
	w_priv->wdd.parent = &client->dev;
	w_priv->wdd.groups = ziirave_wdt_groups;

	ret = watchdog_init_timeout(&w_priv->wdd, wdt_timeout, &client->dev);
	if (ret) {
	dev_info(&client->dev,
	"Unable to select timeout value, using default\n");
	}

	/*
	* The default value set in the watchdog should be perfectly valid, so
	* pass that in if we haven't provided one via the module parameter or
	* of property.
	*/
	if (w_priv->wdd.timeout == 0) {
	val = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_TIMEOUT);
	if (val < 0)
	return val;

	if (val < ZIIRAVE_TIMEOUT_MIN)
	return -ENODEV;

	w_priv->wdd.timeout = val;
	} else {
	ret = ziirave_wdt_set_timeout(&w_priv->wdd,
	w_priv->wdd.timeout);
	if (ret)
	return ret;

	dev_info(&client->dev, "Timeout set to %ds.",
	w_priv->wdd.timeout);
	}

	watchdog_set_nowayout(&w_priv->wdd, nowayout);

	i2c_set_clientdata(client, w_priv);

	/* If in unconfigured state, set to stopped */
	val = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_STATE);
	if (val < 0)
	return val;

	if (val == ZIIRAVE_STATE_INITIAL)
	ziirave_wdt_stop(&w_priv->wdd);

	ret = ziirave_wdt_init_duration(client);
	if (ret)
	return ret;

	ret = ziirave_wdt_revision(client, &w_priv->firmware_rev,
	ZIIRAVE_WDT_FIRM_VER_MAJOR);
	if (ret)
	return ret;

	ret = ziirave_wdt_revision(client, &w_priv->bootloader_rev,
	ZIIRAVE_WDT_BOOT_VER_MAJOR);
	if (ret)
	return ret;

	w_priv->reset_reason = i2c_smbus_read_byte_data(client,
	ZIIRAVE_WDT_RESET_REASON);
	if (w_priv->reset_reason < 0)
	return w_priv->reset_reason;

	if (w_priv->reset_reason >= ARRAY_SIZE(ziirave_reasons) \|\|
	!ziirave_reasons[w_priv->reset_reason])
	return -ENODEV;

	ret = watchdog_register_device(&w_priv->wdd);

	return ret;
	}

	static int ziirave_wdt_remove(struct i2c_client *client)
	{
	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);

	watchdog_unregister_device(&w_priv->wdd);

	return 0;
	}

	static struct i2c_device_id ziirave_wdt_id[] = {
	{ "rave-wdt", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, ziirave_wdt_id);

	static const struct of_device_id zrv_wdt_of_match[] = {
	{ .compatible = "zii,rave-wdt", },
	{ },
	};
	MODULE_DEVICE_TABLE(of, zrv_wdt_of_match);

	static struct i2c_driver ziirave_wdt_driver = {
	.driver = {
	.name = "ziirave_wdt",
	.of_match_table = zrv_wdt_of_match,
	},
	.probe = ziirave_wdt_probe,
	.remove = ziirave_wdt_remove,
	.id_table = ziirave_wdt_id,
	};

	module_i2c_driver(ziirave_wdt_driver);

	MODULE_AUTHOR("Martyn Welch <[email protected]");
	MODULE_DESCRIPTION("Zodiac Aerospace RAVE Switch Watchdog Processor Driver");
	MODULE_LICENSE("GPL");