Initial import

1 files changed, 408 insertions, 0 deletions

diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
new file mode 100644
index 000000000..d0bb9499d
--- /dev/null
+++ b/drivers/watchdog/dw_wdt.c
@@ -0,0 +1,408 @@
+/*
+ * Copyright 2010-2011 Picochip Ltd., Jamie Iles
+ * http://www.picochip.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.
+ *
+ * This file implements a driver for the Synopsys DesignWare watchdog device
+ * in the many subsystems. The watchdog has 16 different timeout periods
+ * and these are a function of the input clock frequency.
+ *
+ * The DesignWare watchdog cannot be stopped once it has been started so we
+ * use a software timer to implement a ping that will keep the watchdog alive.
+ * If we receive an expected close for the watchdog then we keep the timer
+ * running, otherwise the timer is stopped and the watchdog will expire.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/fs.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/pm.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/spinlock.h>
+#include <linux/timer.h>
+#include <linux/uaccess.h>
+#include <linux/watchdog.h>
+
+#define WDOG_CONTROL_REG_OFFSET		    0x00
+#define WDOG_CONTROL_REG_WDT_EN_MASK	    0x01
+#define WDOG_TIMEOUT_RANGE_REG_OFFSET	    0x04
+#define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT    4
+#define WDOG_CURRENT_COUNT_REG_OFFSET	    0x08
+#define WDOG_COUNTER_RESTART_REG_OFFSET     0x0c
+#define WDOG_COUNTER_RESTART_KICK_VALUE	    0x76
+
+/* The maximum TOP (timeout period) value that can be set in the watchdog. */
+#define DW_WDT_MAX_TOP		15
+
+#define DW_WDT_DEFAULT_SECONDS	30
+
+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) ")");
+
+#define WDT_TIMEOUT		(HZ / 2)
+
+static struct {
+	spinlock_t		lock;
+	void __iomem		*regs;
+	struct clk		*clk;
+	unsigned long		in_use;
+	unsigned long		next_heartbeat;
+	struct timer_list	timer;
+	int			expect_close;
+	struct notifier_block	restart_handler;
+} dw_wdt;
+
+static inline int dw_wdt_is_enabled(void)
+{
+	return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
+		WDOG_CONTROL_REG_WDT_EN_MASK;
+}
+
+static inline int dw_wdt_top_in_seconds(unsigned top)
+{
+	/*
+	 * There are 16 possible timeout values in 0..15 where the number of
+	 * cycles is 2 ^ (16 + i) and the watchdog counts down.
+	 */
+	return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk);
+}
+
+static int dw_wdt_get_top(void)
+{
+	int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
+
+	return dw_wdt_top_in_seconds(top);
+}
+
+static inline void dw_wdt_set_next_heartbeat(void)
+{
+	dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
+}
+
+static void dw_wdt_keepalive(void)
+{
+	writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
+	       WDOG_COUNTER_RESTART_REG_OFFSET);
+}
+
+static int dw_wdt_set_top(unsigned top_s)
+{
+	int i, top_val = DW_WDT_MAX_TOP;
+
+	/*
+	 * Iterate over the timeout values until we find the closest match. We
+	 * always look for >=.
+	 */
+	for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
+		if (dw_wdt_top_in_seconds(i) >= top_s) {
+			top_val = i;
+			break;
+		}
+
+	/*
+	 * Set the new value in the watchdog.  Some versions of dw_wdt
+	 * have have TOPINIT in the TIMEOUT_RANGE register (as per
+	 * CP_WDT_DUAL_TOP in WDT_COMP_PARAMS_1).  On those we
+	 * effectively get a pat of the watchdog right here.
+	 */
+	writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
+		dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
+
+	/*
+	 * Add an explicit pat to handle versions of the watchdog that
+	 * don't have TOPINIT.  This won't hurt on versions that have
+	 * it.
+	 */
+	dw_wdt_keepalive();
+
+	dw_wdt_set_next_heartbeat();
+
+	return dw_wdt_top_in_seconds(top_val);
+}
+
+static int dw_wdt_restart_handle(struct notifier_block *this,
+				unsigned long mode, void *cmd)
+{
+	u32 val;
+
+	writel(0, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
+	val = readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
+	if (val & WDOG_CONTROL_REG_WDT_EN_MASK)
+		writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
+			WDOG_COUNTER_RESTART_REG_OFFSET);
+	else
+		writel(WDOG_CONTROL_REG_WDT_EN_MASK,
+		       dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
+
+	/* wait for reset to assert... */
+	mdelay(500);
+
+	return NOTIFY_DONE;
+}
+
+static void dw_wdt_ping(unsigned long data)
+{
+	if (time_before(jiffies, dw_wdt.next_heartbeat) ||
+	    (!nowayout && !dw_wdt.in_use)) {
+		dw_wdt_keepalive();
+		mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
+	} else
+		pr_crit("keepalive missed, machine will reset\n");
+}
+
+static int dw_wdt_open(struct inode *inode, struct file *filp)
+{
+	if (test_and_set_bit(0, &dw_wdt.in_use))
+		return -EBUSY;
+
+	/* Make sure we don't get unloaded. */
+	__module_get(THIS_MODULE);
+
+	spin_lock(&dw_wdt.lock);
+	if (!dw_wdt_is_enabled()) {
+		/*
+		 * The watchdog is not currently enabled. Set the timeout to
+		 * something reasonable and then start it.
+		 */
+		dw_wdt_set_top(DW_WDT_DEFAULT_SECONDS);
+		writel(WDOG_CONTROL_REG_WDT_EN_MASK,
+		       dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
+	}
+
+	dw_wdt_set_next_heartbeat();
+
+	spin_unlock(&dw_wdt.lock);
+
+	return nonseekable_open(inode, filp);
+}
+
+static ssize_t dw_wdt_write(struct file *filp, const char __user *buf,
+			    size_t len, loff_t *offset)
+{
+	if (!len)
+		return 0;
+
+	if (!nowayout) {
+		size_t i;
+
+		dw_wdt.expect_close = 0;
+
+		for (i = 0; i < len; ++i) {
+			char c;
+
+			if (get_user(c, buf + i))
+				return -EFAULT;
+
+			if (c == 'V') {
+				dw_wdt.expect_close = 1;
+				break;
+			}
+		}
+	}
+
+	dw_wdt_set_next_heartbeat();
+	mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
+
+	return len;
+}
+
+static u32 dw_wdt_time_left(void)
+{
+	return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
+		clk_get_rate(dw_wdt.clk);
+}
+
+static const struct watchdog_info dw_wdt_ident = {
+	.options	= WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
+			  WDIOF_MAGICCLOSE,
+	.identity	= "Synopsys DesignWare Watchdog",
+};
+
+static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+	unsigned long val;
+	int timeout;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		return copy_to_user((void __user *)arg, &dw_wdt_ident,
+				    sizeof(dw_wdt_ident)) ? -EFAULT : 0;
+
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		return put_user(0, (int __user *)arg);
+
+	case WDIOC_KEEPALIVE:
+		dw_wdt_set_next_heartbeat();
+		return 0;
+
+	case WDIOC_SETTIMEOUT:
+		if (get_user(val, (int __user *)arg))
+			return -EFAULT;
+		timeout = dw_wdt_set_top(val);
+		return put_user(timeout , (int __user *)arg);
+
+	case WDIOC_GETTIMEOUT:
+		return put_user(dw_wdt_get_top(), (int __user *)arg);
+
+	case WDIOC_GETTIMELEFT:
+		/* Get the time left until expiry. */
+		if (get_user(val, (int __user *)arg))
+			return -EFAULT;
+		return put_user(dw_wdt_time_left(), (int __user *)arg);
+
+	default:
+		return -ENOTTY;
+	}
+}
+
+static int dw_wdt_release(struct inode *inode, struct file *filp)
+{
+	clear_bit(0, &dw_wdt.in_use);
+
+	if (!dw_wdt.expect_close) {
+		del_timer(&dw_wdt.timer);
+
+		if (!nowayout)
+			pr_crit("unexpected close, system will reboot soon\n");
+		else
+			pr_crit("watchdog cannot be disabled, system will reboot soon\n");
+	}
+
+	dw_wdt.expect_close = 0;
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int dw_wdt_suspend(struct device *dev)
+{
+	clk_disable_unprepare(dw_wdt.clk);
+
+	return 0;
+}
+
+static int dw_wdt_resume(struct device *dev)
+{
+	int err = clk_prepare_enable(dw_wdt.clk);
+
+	if (err)
+		return err;
+
+	dw_wdt_keepalive();
+
+	return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
+
+static const struct file_operations wdt_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.open		= dw_wdt_open,
+	.write		= dw_wdt_write,
+	.unlocked_ioctl	= dw_wdt_ioctl,
+	.release	= dw_wdt_release
+};
+
+static struct miscdevice dw_wdt_miscdev = {
+	.fops		= &wdt_fops,
+	.name		= "watchdog",
+	.minor		= WATCHDOG_MINOR,
+};
+
+static int dw_wdt_drv_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	dw_wdt.regs = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(dw_wdt.regs))
+		return PTR_ERR(dw_wdt.regs);
+
+	dw_wdt.clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(dw_wdt.clk))
+		return PTR_ERR(dw_wdt.clk);
+
+	ret = clk_prepare_enable(dw_wdt.clk);
+	if (ret)
+		return ret;
+
+	spin_lock_init(&dw_wdt.lock);
+
+	ret = misc_register(&dw_wdt_miscdev);
+	if (ret)
+		goto out_disable_clk;
+
+	dw_wdt.restart_handler.notifier_call = dw_wdt_restart_handle;
+	dw_wdt.restart_handler.priority = 128;
+	ret = register_restart_handler(&dw_wdt.restart_handler);
+	if (ret)
+		pr_warn("cannot register restart handler\n");
+
+	dw_wdt_set_next_heartbeat();
+	setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
+	mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
+
+	return 0;
+
+out_disable_clk:
+	clk_disable_unprepare(dw_wdt.clk);
+
+	return ret;
+}
+
+static int dw_wdt_drv_remove(struct platform_device *pdev)
+{
+	unregister_restart_handler(&dw_wdt.restart_handler);
+
+	misc_deregister(&dw_wdt_miscdev);
+
+	clk_disable_unprepare(dw_wdt.clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id dw_wdt_of_match[] = {
+	{ .compatible = "snps,dw-wdt", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
+#endif
+
+static struct platform_driver dw_wdt_driver = {
+	.probe		= dw_wdt_drv_probe,
+	.remove		= dw_wdt_drv_remove,
+	.driver		= {
+		.name	= "dw_wdt",
+		.of_match_table = of_match_ptr(dw_wdt_of_match),
+		.pm	= &dw_wdt_pm_ops,
+	},
+};
+
+module_platform_driver(dw_wdt_driver);
+
+MODULE_AUTHOR("Jamie Iles");
+MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
+MODULE_LICENSE("GPL");