--- /dev/null
+/*
+ * 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");
Code Review / kvmfornfv.git / blobdiff