[WATCHDOG] ep93xx: implemented watchdog timer driver for TS-72xx SBCs

Technologic Systems TS-72xx SBCs have external glue logic
CPLD which includes watchdog timer. This driver implements
kernel support for that.

Signed-off-by: Mika Westerberg <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/Kconfig

···
 	  Say Y here if you want support for the watchdog timer on Avionic
 	  Design Xanthos boards.
 
+config TS72XX_WATCHDOG
+	tristate "TS-72XX SBC Watchdog"
+	depends on MACH_TS72XX
+	help
+	  Technologic Systems TS-7200, TS-7250 and TS-7260 boards have
+	  watchdog timer implemented in a external CPLD chip. Say Y here
+	  if you want to support for the watchdog timer on TS-72XX boards.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ts72xx_wdt.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT

drivers/watchdog/Makefile

···
 obj-$(CONFIG_STMP3XXX_WATCHDOG) += stmp3xxx_wdt.o
 obj-$(CONFIG_NUC900_WATCHDOG) += nuc900_wdt.o
 obj-$(CONFIG_ADX_WATCHDOG) += adx_wdt.o
+obj-$(CONFIG_TS72XX_WATCHDOG) += ts72xx_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o

drivers/watchdog/ts72xx_wdt.c

···
+/*
+ * Watchdog driver for Technologic Systems TS-72xx based SBCs
+ * (TS-7200, TS-7250 and TS-7260). These boards have external
+ * glue logic CPLD chip, which includes programmable watchdog
+ * timer.
+ *
+ * Copyright (c) 2009 Mika Westerberg <[e-mail]>
+ *
+ * This driver is based on ep93xx_wdt and wm831x_wdt drivers.
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/fs.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/miscdevice.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/uaccess.h>
+
+#define TS72XX_WDT_FEED_VAL		0x05
+#define TS72XX_WDT_DEFAULT_TIMEOUT	8
+
+static int timeout = TS72XX_WDT_DEFAULT_TIMEOUT;
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. "
+			  "(1 <= timeout <= 8, default="
+			  __MODULE_STRING(TS72XX_WDT_DEFAULT_TIMEOUT)
+			  ")");
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
+
+/**
+ * struct ts72xx_wdt - watchdog control structure
+ * @lock: lock that protects this structure
+ * @regval: watchdog timeout value suitable for control register
+ * @flags: flags controlling watchdog device state
+ * @control_reg: watchdog control register
+ * @feed_reg: watchdog feed register
+ * @pdev: back pointer to platform dev
+ */
+struct ts72xx_wdt {
+	struct mutex	lock;
+	int		regval;
+
+#define TS72XX_WDT_BUSY_FLAG		1
+#define TS72XX_WDT_EXPECT_CLOSE_FLAG	2
+	int		flags;
+
+	void __iomem	*control_reg;
+	void __iomem	*feed_reg;
+
+	struct platform_device *pdev;
+};
+
+struct platform_device *ts72xx_wdt_pdev;
+
+/*
+ * TS-72xx Watchdog supports following timeouts (value written
+ * to control register):
+ *	value	description
+ *	-------------------------
+ * 	0x00	watchdog disabled
+ *	0x01	250ms
+ *	0x02	500ms
+ *	0x03	1s
+ *	0x04	reserved
+ *	0x05	2s
+ *	0x06	4s
+ *	0x07	8s
+ *
+ * Timeouts below 1s are not very usable so we don't
+ * allow them at all.
+ *
+ * We provide two functions that convert between these:
+ * timeout_to_regval() and regval_to_timeout().
+ */
+static const struct {
+	int	timeout;
+	int	regval;
+} ts72xx_wdt_map[] = {
+	{ 1, 3 },
+	{ 2, 5 },
+	{ 4, 6 },
+	{ 8, 7 },
+};
+
+/**
+ * timeout_to_regval() - converts given timeout to control register value
+ * @new_timeout: timeout in seconds to be converted
+ *
+ * Function converts given @new_timeout into valid value that can
+ * be programmed into watchdog control register. When conversion is
+ * not possible, function returns %-EINVAL.
+ */
+static int timeout_to_regval(int new_timeout)
+{
+	int i;
+
+	/* first limit it to 1 - 8 seconds */
+	new_timeout = clamp_val(new_timeout, 1, 8);
+
+	for (i = 0; i < ARRAY_SIZE(ts72xx_wdt_map); i++) {
+		if (ts72xx_wdt_map[i].timeout >= new_timeout)
+			return ts72xx_wdt_map[i].regval;
+	}
+
+	return -EINVAL;
+}
+
+/**
+ * regval_to_timeout() - converts control register value to timeout
+ * @regval: control register value to be converted
+ *
+ * Function converts given @regval to timeout in seconds (1, 2, 4 or 8).
+ * If @regval cannot be converted, function returns %-EINVAL.
+ */
+static int regval_to_timeout(int regval)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(ts72xx_wdt_map); i++) {
+		if (ts72xx_wdt_map[i].regval == regval)
+			return ts72xx_wdt_map[i].timeout;
+	}
+
+	return -EINVAL;
+}
+
+/**
+ * ts72xx_wdt_kick() - kick the watchdog
+ * @wdt: watchdog to be kicked
+ *
+ * Called with @wdt->lock held.
+ */
+static inline void ts72xx_wdt_kick(struct ts72xx_wdt *wdt)
+{
+	__raw_writeb(TS72XX_WDT_FEED_VAL, wdt->feed_reg);
+}
+
+/**
+ * ts72xx_wdt_start() - starts the watchdog timer
+ * @wdt: watchdog to be started
+ *
+ * This function programs timeout to watchdog timer
+ * and starts it.
+ *
+ * Called with @wdt->lock held.
+ */
+static void ts72xx_wdt_start(struct ts72xx_wdt *wdt)
+{
+	/*
+	 * To program the wdt, it first must be "fed" and
+	 * only after that (within 30 usecs) the configuration
+	 * can be changed.
+	 */
+	ts72xx_wdt_kick(wdt);
+	__raw_writeb((u8)wdt->regval, wdt->control_reg);
+}
+
+/**
+ * ts72xx_wdt_stop() - stops the watchdog timer
+ * @wdt: watchdog to be stopped
+ *
+ * Called with @wdt->lock held.
+ */
+static void ts72xx_wdt_stop(struct ts72xx_wdt *wdt)
+{
+	ts72xx_wdt_kick(wdt);
+	__raw_writeb(0, wdt->control_reg);
+}
+
+static int ts72xx_wdt_open(struct inode *inode, struct file *file)
+{
+	struct ts72xx_wdt *wdt = platform_get_drvdata(ts72xx_wdt_pdev);
+	int regval;
+
+	/*
+	 * Try to convert default timeout to valid register
+	 * value first.
+	 */
+	regval = timeout_to_regval(timeout);
+	if (regval < 0) {
+		dev_err(&wdt->pdev->dev,
+			"failed to convert timeout (%d) to register value\n",
+			timeout);
+		return -EINVAL;
+	}
+
+	if (mutex_lock_interruptible(&wdt->lock))
+		return -ERESTARTSYS;
+
+	if ((wdt->flags & TS72XX_WDT_BUSY_FLAG) != 0) {
+		mutex_unlock(&wdt->lock);
+		return -EBUSY;
+	}
+
+	wdt->flags = TS72XX_WDT_BUSY_FLAG;
+	wdt->regval = regval;
+	file->private_data = wdt;
+
+	ts72xx_wdt_start(wdt);
+
+	mutex_unlock(&wdt->lock);
+	return nonseekable_open(inode, file);
+}
+
+static int ts72xx_wdt_release(struct inode *inode, struct file *file)
+{
+	struct ts72xx_wdt *wdt = file->private_data;
+
+	if (mutex_lock_interruptible(&wdt->lock))
+		return -ERESTARTSYS;
+
+	if ((wdt->flags & TS72XX_WDT_EXPECT_CLOSE_FLAG) != 0) {
+		ts72xx_wdt_stop(wdt);
+	} else {
+		dev_warn(&wdt->pdev->dev,
+			 "TS-72XX WDT device closed unexpectly. "
+			 "Watchdog timer will not stop!\n");
+		/*
+		 * Kick it one more time, to give userland some time
+		 * to recover (for example, respawning the kicker
+		 * daemon).
+		 */
+		ts72xx_wdt_kick(wdt);
+	}
+
+	wdt->flags = 0;
+
+	mutex_unlock(&wdt->lock);
+	return 0;
+}
+
+static ssize_t ts72xx_wdt_write(struct file *file,
+				const char __user *data,
+				size_t len,
+				loff_t *ppos)
+{
+	struct ts72xx_wdt *wdt = file->private_data;
+
+	if (!len)
+		return 0;
+
+	if (mutex_lock_interruptible(&wdt->lock))
+		return -ERESTARTSYS;
+
+	ts72xx_wdt_kick(wdt);
+
+	/*
+	 * Support for magic character closing. User process
+	 * writes 'V' into the device, just before it is closed.
+	 * This means that we know that the wdt timer can be
+	 * stopped after user closes the device.
+	 */
+	if (!nowayout) {
+		int i;
+
+		for (i = 0; i < len; i++) {
+			char c;
+
+			/* In case it was set long ago */
+			wdt->flags &= ~TS72XX_WDT_EXPECT_CLOSE_FLAG;
+
+			if (get_user(c, data + i)) {
+				mutex_unlock(&wdt->lock);
+				return -EFAULT;
+			}
+			if (c == 'V') {
+				wdt->flags |= TS72XX_WDT_EXPECT_CLOSE_FLAG;
+				break;
+			}
+		}
+	}
+
+	mutex_unlock(&wdt->lock);
+	return len;
+}
+
+static const struct watchdog_info winfo = {
+	.options		= WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
+				  WDIOF_MAGICCLOSE,
+	.firmware_version	= 1,
+	.identity		= "TS-72XX WDT",
+};
+
+static long ts72xx_wdt_ioctl(struct file *file, unsigned int cmd,
+			     unsigned long arg)
+{
+	struct ts72xx_wdt *wdt = file->private_data;
+	void __user *argp = (void __user *)arg;
+	int __user *p = (int __user *)argp;
+	int error = 0;
+
+	if (mutex_lock_interruptible(&wdt->lock))
+		return -ERESTARTSYS;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		error = copy_to_user(argp, &winfo, sizeof(winfo));
+		break;
+
+	case WDIOC_KEEPALIVE:
+		ts72xx_wdt_kick(wdt);
+		break;
+
+	case WDIOC_SETOPTIONS: {
+		int options;
+
+		if (get_user(options, p)) {
+			error = -EFAULT;
+			break;
+		}
+
+		error = -EINVAL;
+
+		if ((options & WDIOS_DISABLECARD) != 0) {
+			ts72xx_wdt_stop(wdt);
+			error = 0;
+		}
+		if ((options & WDIOS_ENABLECARD) != 0) {
+			ts72xx_wdt_start(wdt);
+			error = 0;
+		}
+
+		break;
+	}
+
+	case WDIOC_SETTIMEOUT: {
+		int new_timeout;
+
+		if (get_user(new_timeout, p)) {
+			error = -EFAULT;
+		} else {
+			int regval;
+
+			regval = timeout_to_regval(new_timeout);
+			if (regval < 0) {
+				error = -EINVAL;
+			} else {
+				ts72xx_wdt_stop(wdt);
+				wdt->regval = regval;
+				ts72xx_wdt_start(wdt);
+			}
+		}
+		if (error)
+			break;
+
+		/*FALLTHROUGH*/
+	}
+
+	case WDIOC_GETTIMEOUT:
+		if (put_user(regval_to_timeout(wdt->regval), p))
+			error = -EFAULT;
+		break;
+
+	default:
+		error = -ENOTTY;
+		break;
+	}
+
+	mutex_unlock(&wdt->lock);
+	return error;
+}
+
+static const struct file_operations ts72xx_wdt_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.open		= ts72xx_wdt_open,
+	.release	= ts72xx_wdt_release,
+	.write		= ts72xx_wdt_write,
+	.unlocked_ioctl	= ts72xx_wdt_ioctl,
+};
+
+static struct miscdevice ts72xx_wdt_miscdev = {
+	.minor		= WATCHDOG_MINOR,
+	.name		= "watchdog",
+	.fops		= &ts72xx_wdt_fops,
+};
+
+static __devinit int ts72xx_wdt_probe(struct platform_device *pdev)
+{
+	struct ts72xx_wdt *wdt;
+	struct resource *r1, *r2;
+	int error = 0;
+
+	wdt = kzalloc(sizeof(struct ts72xx_wdt), GFP_KERNEL);
+	if (!wdt) {
+		dev_err(&pdev->dev, "failed to allocate memory\n");
+		return -ENOMEM;
+	}
+
+	r1 = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!r1) {
+		dev_err(&pdev->dev, "failed to get memory resource\n");
+		error = -ENODEV;
+		goto fail;
+	}
+
+	r1 = request_mem_region(r1->start, resource_size(r1), pdev->name);
+	if (!r1) {
+		dev_err(&pdev->dev, "cannot request memory region\n");
+		error = -EBUSY;
+		goto fail;
+	}
+
+	wdt->control_reg = ioremap(r1->start, resource_size(r1));
+	if (!wdt->control_reg) {
+		dev_err(&pdev->dev, "failed to map memory\n");
+		error = -ENODEV;
+		goto fail_free_control;
+	}
+
+	r2 = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (!r2) {
+		dev_err(&pdev->dev, "failed to get memory resource\n");
+		error = -ENODEV;
+		goto fail_unmap_control;
+	}
+
+	r2 = request_mem_region(r2->start, resource_size(r2), pdev->name);
+	if (!r2) {
+		dev_err(&pdev->dev, "cannot request memory region\n");
+		error = -EBUSY;
+		goto fail_unmap_control;
+	}
+
+	wdt->feed_reg = ioremap(r2->start, resource_size(r2));
+	if (!wdt->feed_reg) {
+		dev_err(&pdev->dev, "failed to map memory\n");
+		error = -ENODEV;
+		goto fail_free_feed;
+	}
+
+	platform_set_drvdata(pdev, wdt);
+	ts72xx_wdt_pdev = pdev;
+	wdt->pdev = pdev;
+	mutex_init(&wdt->lock);
+
+	error = misc_register(&ts72xx_wdt_miscdev);
+	if (error) {
+		dev_err(&pdev->dev, "failed to register miscdev\n");
+		goto fail_unmap_feed;
+	}
+
+	dev_info(&pdev->dev, "TS-72xx Watchdog driver\n");
+
+	return 0;
+
+fail_unmap_feed:
+	platform_set_drvdata(pdev, NULL);
+	iounmap(wdt->feed_reg);
+fail_free_feed:
+	release_mem_region(r2->start, resource_size(r2));
+fail_unmap_control:
+	iounmap(wdt->control_reg);
+fail_free_control:
+	release_mem_region(r1->start, resource_size(r1));
+fail:
+	kfree(wdt);
+	return error;
+}
+
+static __devexit int ts72xx_wdt_remove(struct platform_device *pdev)
+{
+	struct ts72xx_wdt *wdt = platform_get_drvdata(pdev);
+	struct resource *res;
+	int error;
+
+	error = misc_deregister(&ts72xx_wdt_miscdev);
+	platform_set_drvdata(pdev, NULL);
+
+	iounmap(wdt->control_reg);
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	release_mem_region(res->start, resource_size(res));
+
+	iounmap(wdt->feed_reg);
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	release_mem_region(res->start, resource_size(res));
+
+	kfree(wdt);
+	return error;
+}
+
+static struct platform_driver ts72xx_wdt_driver = {
+	.probe		= ts72xx_wdt_probe,
+	.remove		= __devexit_p(ts72xx_wdt_remove),
+	.driver		= {
+		.name	= "ts72xx-wdt",
+		.owner	= THIS_MODULE,
+	},
+};
+
+static __init int ts72xx_wdt_init(void)
+{
+	return platform_driver_register(&ts72xx_wdt_driver);
+}
+module_init(ts72xx_wdt_init);
+
+static __exit void ts72xx_wdt_exit(void)
+{
+	platform_driver_unregister(&ts72xx_wdt_driver);
+}
+module_exit(ts72xx_wdt_exit);
+
+MODULE_AUTHOR("Mika Westerberg <[e-mail]>");
+MODULE_DESCRIPTION("TS-72xx SBC Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ts72xx-wdt");