[ARM SMP] Add MPCore watchdog driver

Add platform independent parts of the ARM MPCore watchdog driver.

Signed-off-by: Russell King <[e-mail]>

drivers/char/watchdog/Kconfig

···
 	  To compile this driver as a module, choose M here: the
 	  module will be called sa1100_wdt.
 
+config MPCORE_WATCHDOG
+	tristate "MPcore watchdog"
+	depends on WATCHDOG && ARM_MPCORE_PLATFORM && LOCAL_TIMERS
+	help
+	  Watchdog timer embedded into the MPcore system.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called mpcore_wdt.
+
 # X86 (i386 + ia64 + x86_64) Architecture
 
 config ACQUIRE_WDT

drivers/char/watchdog/Makefile

···
 obj-$(CONFIG_IXP4XX_WATCHDOG) += ixp4xx_wdt.o
 obj-$(CONFIG_S3C2410_WATCHDOG) += s3c2410_wdt.o
 obj-$(CONFIG_SA1100_WATCHDOG) += sa1100_wdt.o
+obj-$(CONFIG_MPCORE_WATCHDOG) += mpcore_wdt.o
 
 # X86 (i386 + ia64 + x86_64) Architecture
 obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o

drivers/char/watchdog/mpcore_wdt.c

···
+/*
+ *	Watchdog driver for the mpcore watchdog timer
+ *
+ *	(c) Copyright 2004 ARM Limited
+ *
+ *	Based on the SoftDog driver:
+ *	(c) Copyright 1996 Alan Cox <[e-mail]>, All Rights Reserved.
+ *				http://www.redhat.com
+ *
+ *	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.
+ *
+ *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
+ *	warranty for any of this software. This material is provided
+ *	"AS-IS" and at no charge.
+ *
+ *	(c) Copyright 1995    Alan Cox <[e-mail]>
+ *
+ */
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/config.h>
+#include <linux/types.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/fs.h>
+#include <linux/reboot.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/device.h>
+#include <asm/uaccess.h>
+
+struct mpcore_wdt {
+	unsigned long	timer_alive;
+	struct device	*dev;
+	void __iomem	*base;
+	int		irq;
+	unsigned int	perturb;
+	char		expect_close;
+};
+
+static struct platform_device *mpcore_wdt_dev;
+
+extern unsigned int mpcore_timer_rate;
+
+#define TIMER_MARGIN	60
+static int mpcore_margin = TIMER_MARGIN;
+module_param(mpcore_margin, int, 0);
+MODULE_PARM_DESC(mpcore_margin, "MPcore timer margin in seconds. (0<mpcore_margin<65536, default=" __MODULE_STRING(TIMER_MARGIN) ")");
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+#define ONLY_TESTING	0
+static int mpcore_noboot = ONLY_TESTING;
+module_param(mpcore_noboot, int, 0);
+MODULE_PARM_DESC(mpcore_noboot, "MPcore watchdog action, set to 1 to ignore reboots, 0 to reboot (default=" __MODULE_STRING(ONLY_TESTING) ")");
+
+/*
+ *	This is the interrupt handler.  Note that we only use this
+ *	in testing mode, so don't actually do a reboot here.
+ */
+static irqreturn_t mpcore_wdt_fire(int irq, void *arg, struct pt_regs *regs)
+{
+	struct mpcore_wdt *wdt = arg;
+
+	/* Check it really was our interrupt */
+	if (readl(wdt->base + TWD_WDOG_INTSTAT)) {
+		dev_printk(KERN_CRIT, wdt->dev, "Triggered - Reboot ignored.\n");
+
+		/* Clear the interrupt on the watchdog */
+		writel(1, wdt->base + TWD_WDOG_INTSTAT);
+
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+/*
+ *	mpcore_wdt_keepalive - reload the timer
+ *
+ *	Note that the spec says a DIFFERENT value must be written to the reload
+ *	register each time.  The "perturb" variable deals with this by adding 1
+ *	to the count every other time the function is called.
+ */
+static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
+{
+	unsigned int count;
+
+	/* Assume prescale is set to 256 */
+	count = (mpcore_timer_rate / 256) * mpcore_margin;
+
+	/* Reload the counter */
+	writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);
+
+	wdt->perturb = wdt->perturb ? 0 : 1;
+}
+
+static void mpcore_wdt_stop(struct mpcore_wdt *wdt)
+{
+	writel(0x12345678, wdt->base + TWD_WDOG_DISABLE);
+	writel(0x87654321, wdt->base + TWD_WDOG_DISABLE);
+	writel(0x0, wdt->base + TWD_WDOG_CONTROL);
+}
+
+static void mpcore_wdt_start(struct mpcore_wdt *wdt)
+{
+	dev_printk(KERN_INFO, wdt->dev, "enabling watchdog.\n");
+
+	/* This loads the count register but does NOT start the count yet */
+	mpcore_wdt_keepalive(wdt);
+
+	if (mpcore_noboot) {
+		/* Enable watchdog - prescale=256, watchdog mode=0, enable=1 */
+		writel(0x0000FF01, wdt->base + TWD_WDOG_CONTROL);
+	} else {
+		/* Enable watchdog - prescale=256, watchdog mode=1, enable=1 */
+		writel(0x0000FF09, wdt->base + TWD_WDOG_CONTROL);
+	}
+}
+
+static int mpcore_wdt_set_heartbeat(int t)
+{
+	if (t < 0x0001 || t > 0xFFFF)
+		return -EINVAL;
+
+	mpcore_margin = t;
+	return 0;
+}
+
+/*
+ *	/dev/watchdog handling
+ */
+static int mpcore_wdt_open(struct inode *inode, struct file *file)
+{
+	struct mpcore_wdt *wdt = dev_get_drvdata(&mpcore_wdt_dev->dev);
+
+	if (test_and_set_bit(0, &wdt->timer_alive))
+		return -EBUSY;
+
+	if (nowayout)
+		__module_get(THIS_MODULE);
+
+	file->private_data = wdt;
+
+	/*
+	 *	Activate timer
+	 */
+	mpcore_wdt_start(wdt);
+
+	return nonseekable_open(inode, file);
+}
+
+static int mpcore_wdt_release(struct inode *inode, struct file *file)
+{
+	struct mpcore_wdt *wdt = file->private_data;
+
+	/*
+	 *	Shut off the timer.
+	 * 	Lock it in if it's a module and we set nowayout
+	 */
+	if (wdt->expect_close == 42) {
+		mpcore_wdt_stop(wdt);
+	} else {
+		dev_printk(KERN_CRIT, wdt->dev, "unexpected close, not stopping watchdog!\n");
+		mpcore_wdt_keepalive(wdt);
+	}
+	clear_bit(0, &wdt->timer_alive);
+	wdt->expect_close = 0;
+	return 0;
+}
+
+static ssize_t mpcore_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
+{
+	struct mpcore_wdt *wdt = file->private_data;
+
+	/*  Can't seek (pwrite) on this device  */
+	if (ppos != &file->f_pos)
+		return -ESPIPE;
+
+	/*
+	 *	Refresh the timer.
+	 */
+	if (len) {
+		if (!nowayout) {
+			size_t i;
+
+			/* In case it was set long ago */
+			wdt->expect_close = 0;
+
+			for (i = 0; i != len; i++) {
+				char c;
+
+				if (get_user(c, data + i))
+					return -EFAULT;
+				if (c == 'V')
+					wdt->expect_close = 42;
+			}
+		}
+		mpcore_wdt_keepalive(wdt);
+	}
+	return len;
+}
+
+static struct watchdog_info ident = {
+	.options		= WDIOF_SETTIMEOUT |
+				  WDIOF_KEEPALIVEPING |
+				  WDIOF_MAGICCLOSE,
+	.identity		= "MPcore Watchdog",
+};
+
+static int mpcore_wdt_ioctl(struct inode *inode, struct file *file,
+			     unsigned int cmd, unsigned long arg)
+{
+	struct mpcore_wdt *wdt = file->private_data;
+	int ret;
+	union {
+		struct watchdog_info ident;
+		int i;
+	} uarg;
+
+	if (_IOC_DIR(cmd) && _IOC_SIZE(cmd) > sizeof(uarg))
+		return -ENOIOCTLCMD;
+
+	if (_IOC_DIR(cmd) & _IOC_WRITE) {
+		ret = copy_from_user(&uarg, (void __user *)arg, _IOC_SIZE(cmd));
+		if (ret)
+			return -EFAULT;
+	}
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		uarg.ident = ident;
+		ret = 0;
+		break;
+
+	case WDIOC_SETOPTIONS:
+		ret = -EINVAL;
+		if (uarg.i & WDIOS_DISABLECARD) {
+			mpcore_wdt_stop(wdt);
+			ret = 0;
+		}
+		if (uarg.i & WDIOS_ENABLECARD) {
+			mpcore_wdt_start(wdt);
+			ret = 0;
+		}
+		break;
+
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		uarg.i = 0;
+		ret = 0;
+		break;
+
+	case WDIOC_KEEPALIVE:
+		mpcore_wdt_keepalive(wdt);
+		ret = 0;
+		break;
+
+	case WDIOC_SETTIMEOUT:
+		ret = mpcore_wdt_set_heartbeat(uarg.i);
+		if (ret)
+			break;
+
+		mpcore_wdt_keepalive(wdt);
+		/* Fall */
+	case WDIOC_GETTIMEOUT:
+		uarg.i = mpcore_margin;
+		ret = 0;
+		break;
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+
+	if (ret == 0 && _IOC_DIR(cmd) & _IOC_READ) {
+		ret = copy_to_user((void __user *)arg, &uarg, _IOC_SIZE(cmd));
+		if (ret)
+			ret = -EFAULT;
+	}
+	return ret;
+}
+
+/*
+ *	System shutdown handler.  Turn off the watchdog if we're
+ *	restarting or halting the system.
+ */
+static void mpcore_wdt_shutdown(struct device *_dev)
+{
+	struct mpcore_wdt *wdt = dev_get_drvdata(_dev);
+
+	if (system_state == SYSTEM_RESTART || system_state == SYSTEM_HALT)
+		mpcore_wdt_stop(wdt);
+}
+
+/*
+ *	Kernel Interfaces
+ */
+static struct file_operations mpcore_wdt_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.write		= mpcore_wdt_write,
+	.ioctl		= mpcore_wdt_ioctl,
+	.open		= mpcore_wdt_open,
+	.release	= mpcore_wdt_release,
+};
+
+static struct miscdevice mpcore_wdt_miscdev = {
+	.minor		= WATCHDOG_MINOR,
+	.name		= "watchdog",
+	.fops		= &mpcore_wdt_fops,
+};
+
+static int __devinit mpcore_wdt_probe(struct device *_dev)
+{
+	struct platform_device *dev = to_platform_device(_dev);
+	struct mpcore_wdt *wdt;
+	struct resource *res;
+	int ret;
+
+	/* We only accept one device, and it must have an id of -1 */
+	if (dev->id != -1)
+		return -ENODEV;
+
+	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
+	if (!res) {
+		ret = -ENODEV;
+		goto err_out;
+	}
+
+	wdt = kmalloc(sizeof(struct mpcore_wdt), GFP_KERNEL);
+	if (!wdt) {
+		ret = -ENOMEM;
+		goto err_out;
+	}
+	memset(wdt, 0, sizeof(struct mpcore_wdt));
+
+	wdt->dev = &dev->dev;
+	wdt->irq = platform_get_irq(dev, 0);
+	wdt->base = ioremap(res->start, res->end - res->start + 1);
+	if (!wdt->base) {
+		ret = -ENOMEM;
+		goto err_free;
+	}
+
+	mpcore_wdt_miscdev.dev = &dev->dev;
+	ret = misc_register(&mpcore_wdt_miscdev);
+	if (ret) {
+		dev_printk(KERN_ERR, _dev, "cannot register miscdev on minor=%d (err=%d)\n",
+			   WATCHDOG_MINOR, ret);
+		goto err_misc;
+	}
+
+	ret = request_irq(wdt->irq, mpcore_wdt_fire, SA_INTERRUPT, "mpcore_wdt", wdt);
+	if (ret) {
+		dev_printk(KERN_ERR, _dev, "cannot register IRQ%d for watchdog\n", wdt->irq);
+		goto err_irq;
+	}
+
+	mpcore_wdt_stop(wdt);
+	dev_set_drvdata(&dev->dev, wdt);
+	mpcore_wdt_dev = dev;
+
+	return 0;
+
+ err_irq:
+	misc_deregister(&mpcore_wdt_miscdev);
+ err_misc:
+	iounmap(wdt->base);
+ err_free:
+	kfree(wdt);
+ err_out:
+	return ret;
+}
+
+static int __devexit mpcore_wdt_remove(struct device *dev)
+{
+	struct mpcore_wdt *wdt = dev_get_drvdata(dev);
+
+	dev_set_drvdata(dev, NULL);
+
+	misc_deregister(&mpcore_wdt_miscdev);
+
+	mpcore_wdt_dev = NULL;
+
+	free_irq(wdt->irq, wdt);
+	iounmap(wdt->base);
+	kfree(wdt);
+	return 0;
+}
+
+static struct device_driver mpcore_wdt_driver = {
+	.name		= "mpcore_wdt",
+	.bus		= &platform_bus_type,
+	.probe		= mpcore_wdt_probe,
+	.remove		= __devexit_p(mpcore_wdt_remove),
+	.shutdown	= mpcore_wdt_shutdown,
+};
+
+static char banner[] __initdata = KERN_INFO "MPcore Watchdog Timer: 0.1. mpcore_noboot=%d mpcore_margin=%d sec (nowayout= %d)\n";
+
+static int __init mpcore_wdt_init(void)
+{
+	/*
+	 * Check that the margin value is within it's range;
+	 * if not reset to the default
+	 */
+	if (mpcore_wdt_set_heartbeat(mpcore_margin)) {
+		mpcore_wdt_set_heartbeat(TIMER_MARGIN);
+		printk(KERN_INFO "mpcore_margin value must be 0<mpcore_margin<65536, using %d\n",
+			TIMER_MARGIN);
+	}
+
+	printk(banner, mpcore_noboot, mpcore_margin, nowayout);
+
+	return driver_register(&mpcore_wdt_driver);
+}
+
+static void __exit mpcore_wdt_exit(void)
+{
+	driver_unregister(&mpcore_wdt_driver);
+}
+
+module_init(mpcore_wdt_init);
+module_exit(mpcore_wdt_exit);
+
+MODULE_AUTHOR("ARM Limited");
+MODULE_DESCRIPTION("MPcore Watchdog Device Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);