watchdog: Driver for the watchdog timer on Freescale IMX2 (and later) processors.

This is the driver for the hardware watchdog on the Freescale IMX2 and later processors.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Vladimir Zapolskiy <vzapolskiy@gmail.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Tested-by: Juergen Beisert <jbe@pengutronix.de>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

1 files changed, 358 insertions, 0 deletions

diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
new file mode 100644
index 00000000000..ea25885781b
--- /dev/null
+++ b/drivers/watchdog/imx2_wdt.c
@@ -0,0 +1,358 @@
+/*
+ * Watchdog driver for IMX2 and later processors
+ *
+ *  Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <w.sang@pengutronix.de>
+ *
+ * some parts adapted by similar drivers from Darius Augulis and Vladimir
+ * Zapolskiy, additional improvements by Wim Van Sebroeck.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * NOTE: MX1 has a slightly different Watchdog than MX2 and later:
+ *
+ *                      MX1:            MX2+:
+ *                      ----            -----
+ * Registers:           32-bit          16-bit
+ * Stopable timer:      Yes             No
+ * Need to enable clk:  No              Yes
+ * Halt on suspend:     Manual          Can be automatic
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/clk.h>
+#include <linux/fs.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+#include <linux/timer.h>
+#include <linux/jiffies.h>
+#include <mach/hardware.h>
+
+#define DRIVER_NAME "imx2-wdt"
+
+#define IMX2_WDT_WCR            0x00            /* Control Register */
+#define IMX2_WDT_WCR_WT         (0xFF << 8)     /* -> Watchdog Timeout Field */
+#define IMX2_WDT_WCR_WRE        (1 << 3)        /* -> WDOG Reset Enable */
+#define IMX2_WDT_WCR_WDE        (1 << 2)        /* -> Watchdog Enable */
+
+#define IMX2_WDT_WSR            0x02            /* Service Register */
+#define IMX2_WDT_SEQ1           0x5555          /* -> service sequence 1 */
+#define IMX2_WDT_SEQ2           0xAAAA          /* -> service sequence 2 */
+
+#define IMX2_WDT_MAX_TIME       128
+#define IMX2_WDT_DEFAULT_TIME   60              /* in seconds */
+
+#define WDOG_SEC_TO_COUNT(s)    ((s * 2 - 1) << 8)
+
+#define IMX2_WDT_STATUS_OPEN    0
+#define IMX2_WDT_STATUS_STARTED 1
+#define IMX2_WDT_EXPECT_CLOSE   2
+
+static struct {
+        struct clk *clk;
+        void __iomem *base;
+        unsigned timeout;
+        unsigned long status;
+        struct timer_list timer;        /* Pings the watchdog when closed */
+} imx2_wdt;
+
+static struct miscdevice imx2_wdt_miscdev;
+
+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) ")");
+
+
+static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
+                                __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
+
+static const struct watchdog_info imx2_wdt_info = {
+        .identity = "imx2+ watchdog",
+        .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
+};
+
+static inline void imx2_wdt_setup(void)
+{
+        u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
+
+        /* Strip the old watchdog Time-Out value */
+        val &= ~IMX2_WDT_WCR_WT;
+        /* Generate reset if WDOG times out */
+        val &= ~IMX2_WDT_WCR_WRE;
+        /* Keep Watchdog Disabled */
+        val &= ~IMX2_WDT_WCR_WDE;
+        /* Set the watchdog's Time-Out value */
+        val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout);
+
+        __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
+
+        /* enable the watchdog */
+        val |= IMX2_WDT_WCR_WDE;
+        __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
+}
+
+static inline void imx2_wdt_ping(void)
+{
+        __raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
+        __raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
+}
+
+static void imx2_wdt_timer_ping(unsigned long arg)
+{
+        /* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
+        imx2_wdt_ping();
+        mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
+}
+
+static void imx2_wdt_start(void)
+{
+        if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
+                /* at our first start we enable clock and do initialisations */
+                clk_enable(imx2_wdt.clk);
+
+                imx2_wdt_setup();
+        } else  /* delete the timer that pings the watchdog after close */
+                del_timer_sync(&imx2_wdt.timer);
+
+        /* Watchdog is enabled - time to reload the timeout value */
+        imx2_wdt_ping();
+}
+
+static void imx2_wdt_stop(void)
+{
+        /* we don't need a clk_disable, it cannot be disabled once started.
+         * We use a timer to ping the watchdog while /dev/watchdog is closed */
+        imx2_wdt_timer_ping(0);
+}
+
+static void imx2_wdt_set_timeout(int new_timeout)
+{
+        u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
+
+        /* set the new timeout value in the WSR */
+        val &= ~IMX2_WDT_WCR_WT;
+        val |= WDOG_SEC_TO_COUNT(new_timeout);
+        __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
+}
+
+static int imx2_wdt_open(struct inode *inode, struct file *file)
+{
+        if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
+                return -EBUSY;
+
+        imx2_wdt_start();
+        return nonseekable_open(inode, file);
+}
+
+static int imx2_wdt_close(struct inode *inode, struct file *file)
+{
+        if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
+                imx2_wdt_stop();
+        else {
+                dev_crit(imx2_wdt_miscdev.parent,
+                        "Unexpected close: Expect reboot!\n");
+                imx2_wdt_ping();
+        }
+
+        clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
+        clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
+        return 0;
+}
+
+static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
+                                                        unsigned long arg)
+{
+        void __user *argp = (void __user *)arg;
+        int __user *p = argp;
+        int new_value;
+
+        switch (cmd) {
+        case WDIOC_GETSUPPORT:
+                return copy_to_user(argp, &imx2_wdt_info,
+                        sizeof(struct watchdog_info)) ? -EFAULT : 0;
+
+        case WDIOC_GETSTATUS:
+        case WDIOC_GETBOOTSTATUS:
+                return put_user(0, p);
+
+        case WDIOC_KEEPALIVE:
+                imx2_wdt_ping();
+                return 0;
+
+        case WDIOC_SETTIMEOUT:
+                if (get_user(new_value, p))
+                        return -EFAULT;
+                if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
+                        return -EINVAL;
+                imx2_wdt_set_timeout(new_value);
+                imx2_wdt.timeout = new_value;
+                imx2_wdt_ping();
+
+                /* Fallthrough to return current value */
+        case WDIOC_GETTIMEOUT:
+                return put_user(imx2_wdt.timeout, p);
+
+        default:
+                return -ENOTTY;
+        }
+}
+
+static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
+                                                size_t len, loff_t *ppos)
+{
+        size_t i;
+        char c;
+
+        if (len == 0)   /* Can we see this even ? */
+                return 0;
+
+        clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
+        /* scan to see whether or not we got the magic character */
+        for (i = 0; i != len; i++) {
+                if (get_user(c, data + i))
+                        return -EFAULT;
+                if (c == 'V')
+                        set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
+        }
+
+        imx2_wdt_ping();
+        return len;
+}
+
+static const struct file_operations imx2_wdt_fops = {
+        .owner = THIS_MODULE,
+        .llseek = no_llseek,
+        .unlocked_ioctl = imx2_wdt_ioctl,
+        .open = imx2_wdt_open,
+        .release = imx2_wdt_close,
+        .write = imx2_wdt_write,
+};
+
+static struct miscdevice imx2_wdt_miscdev = {
+        .minor = WATCHDOG_MINOR,
+        .name = "watchdog",
+        .fops = &imx2_wdt_fops,
+};
+
+static int __init imx2_wdt_probe(struct platform_device *pdev)
+{
+        int ret;
+        int res_size;
+        struct resource *res;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (!res) {
+                dev_err(&pdev->dev, "can't get device resources\n");
+                return -ENODEV;
+        }
+
+        res_size = resource_size(res);
+        if (!devm_request_mem_region(&pdev->dev, res->start, res_size,
+                res->name)) {
+                dev_err(&pdev->dev, "can't allocate %d bytes at %d address\n",
+                        res_size, res->start);
+                return -ENOMEM;
+        }
+
+        imx2_wdt.base = devm_ioremap_nocache(&pdev->dev, res->start, res_size);
+        if (!imx2_wdt.base) {
+                dev_err(&pdev->dev, "ioremap failed\n");
+                return -ENOMEM;
+        }
+
+        imx2_wdt.clk = clk_get_sys("imx-wdt.0", NULL);
+        if (IS_ERR(imx2_wdt.clk)) {
+                dev_err(&pdev->dev, "can't get Watchdog clock\n");
+                return PTR_ERR(imx2_wdt.clk);
+        }
+
+        imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
+        if (imx2_wdt.timeout != timeout)
+                dev_warn(&pdev->dev, "Initial timeout out of range! "
+                        "Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
+
+        setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
+
+        imx2_wdt_miscdev.parent = &pdev->dev;
+        ret = misc_register(&imx2_wdt_miscdev);
+        if (ret)
+                goto fail;
+
+        dev_info(&pdev->dev,
+                "IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n",
+                                                imx2_wdt.timeout, nowayout);
+        return 0;
+
+fail:
+        imx2_wdt_miscdev.parent = NULL;
+        clk_put(imx2_wdt.clk);
+        return ret;
+}
+
+static int __exit imx2_wdt_remove(struct platform_device *pdev)
+{
+        misc_deregister(&imx2_wdt_miscdev);
+
+        if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
+                del_timer_sync(&imx2_wdt.timer);
+
+                dev_crit(imx2_wdt_miscdev.parent,
+                        "Device removed: Expect reboot!\n");
+        } else
+                clk_put(imx2_wdt.clk);
+
+        imx2_wdt_miscdev.parent = NULL;
+        return 0;
+}
+
+static void imx2_wdt_shutdown(struct platform_device *pdev)
+{
+        if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
+                /* we are running, we need to delete the timer but will give
+                 * max timeout before reboot will take place */
+                del_timer_sync(&imx2_wdt.timer);
+                imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
+                imx2_wdt_ping();
+
+                dev_crit(imx2_wdt_miscdev.parent,
+                        "Device shutdown: Expect reboot!\n");
+        }
+}
+
+static struct platform_driver imx2_wdt_driver = {
+        .probe          = imx2_wdt_probe,
+        .remove         = __exit_p(imx2_wdt_remove),
+        .shutdown       = imx2_wdt_shutdown,
+        .driver         = {
+                .name   = DRIVER_NAME,
+                .owner  = THIS_MODULE,
+        },
+};
+
+static int __init imx2_wdt_init(void)
+{
+        return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
+}
+module_init(imx2_wdt_init);
+
+static void __exit imx2_wdt_exit(void)
+{
+        platform_driver_unregister(&imx2_wdt_driver);
+}
+module_exit(imx2_wdt_exit);
+
+MODULE_AUTHOR("Wolfram Sang");
+MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
+MODULE_ALIAS("platform:" DRIVER_NAME);