[WATCHDOG] Watchdog driver for AT32AP700X devices

Add support for the built in watchdog in AT32AP700X devices.

Tested on AT32AP7000 and ATSTK1000.

Hardware documentation can be found in the AT32AP7000 datasheet.

Signed-off-by: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 313 insertions, 0 deletions

diff --git a/drivers/char/watchdog/at32ap700x_wdt.c b/drivers/char/watchdog/at32ap700x_wdt.c
new file mode 100644
index 00000000000..036d83bcb50
--- /dev/null
+++ b/drivers/char/watchdog/at32ap700x_wdt.c
@@ -0,0 +1,313 @@
+/*
+ * Watchdog driver for Atmel AT32AP700X devices
+ *
+ * Copyright (C) 2005-2006 Atmel Corporation
+ *
+ * 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.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+
+#include <asm/uaccess.h>
+#include <asm/io.h>
+
+#define TIMEOUT_MIN             1
+#define TIMEOUT_DEFAULT         CONFIG_AT32AP700X_WDT_TIMEOUT
+#define TIMEOUT_MAX             2
+
+/* Watchdog registers and write/read macro */
+#define WDT_CTRL                0x00
+#define WDT_CTRL_EN                0
+#define WDT_CTRL_PSEL              8
+#define WDT_CTRL_KEY              24
+
+#define WDT_CLR                 0x04
+
+#define WDT_BIT(name)           (1 << WDT_##name)
+#define WDT_BF(name,value)      ((value) << WDT_##name)
+
+#define wdt_readl(dev,reg)                              \
+        __raw_readl((dev)->regs + WDT_##reg)
+#define wdt_writel(dev,reg,value)                       \
+        __raw_writel((value), (dev)->regs + WDT_##reg)
+
+struct wdt_at32ap700x {
+        void __iomem            *regs;
+        int                     timeout;
+        int                     users;
+        struct miscdevice       miscdev;
+};
+
+static struct wdt_at32ap700x *wdt;
+
+/*
+ * Disable the watchdog.
+ */
+static void inline at32_wdt_stop(void)
+{
+        unsigned long psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f);
+        wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55));
+        wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa));
+}
+
+/*
+ * Enable and reset the watchdog.
+ */
+static void inline at32_wdt_start(void)
+{
+        /* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */
+        unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe;
+
+        wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
+                        | WDT_BF(CTRL_PSEL, psel)
+                        | WDT_BF(CTRL_KEY, 0x55));
+        wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
+                        | WDT_BF(CTRL_PSEL, psel)
+                        | WDT_BF(CTRL_KEY, 0xaa));
+}
+
+/*
+ * Pat the watchdog timer.
+ */
+static void inline at32_wdt_pat(void)
+{
+        wdt_writel(wdt, CLR, 0x42);
+}
+
+/*
+ * Watchdog device is opened, and watchdog starts running.
+ */
+static int at32_wdt_open(struct inode *inode, struct file *file)
+{
+        if (test_and_set_bit(1, &wdt->users))
+                return -EBUSY;
+
+        at32_wdt_start();
+        return nonseekable_open(inode, file);
+}
+
+/*
+ * Close the watchdog device. If CONFIG_WATCHDOG_NOWAYOUT is _not_ defined then
+ * the watchdog is also disabled.
+ */
+static int at32_wdt_close(struct inode *inode, struct file *file)
+{
+#ifndef CONFIG_WATCHDOG_NOWAYOUT
+        at32_wdt_stop();
+#endif
+        clear_bit(1, &wdt->users);
+        return 0;
+}
+
+/*
+ * Change the watchdog time interval.
+ */
+static int at32_wdt_settimeout(int time)
+{
+        /*
+         * All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is
+         * 2 ^ 16 allowing up to 2 seconds timeout.
+         */
+        if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX))
+                return -EINVAL;
+
+        /* Set new watchdog time. It will be used when at32_wdt_start() is called. */
+        wdt->timeout = time;
+        return 0;
+}
+
+static struct watchdog_info at32_wdt_info = {
+        .identity       = "at32ap700x watchdog",
+        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+};
+
+/*
+ * Handle commands from user-space.
+ */
+static int at32_wdt_ioctl(struct inode *inode, struct file *file,
+                unsigned int cmd, unsigned long arg)
+{
+        int ret = -ENOTTY;
+        int time;
+        void __user *argp = (void __user *)arg;
+        int __user *p = argp;
+
+        switch(cmd) {
+        case WDIOC_KEEPALIVE:
+                at32_wdt_pat();
+                ret = 0;
+                break;
+        case WDIOC_GETSUPPORT:
+                ret = copy_to_user(argp, &at32_wdt_info,
+                                sizeof(at32_wdt_info)) ? -EFAULT : 0;
+                break;
+        case WDIOC_SETTIMEOUT:
+                ret = get_user(time, p);
+                if (ret)
+                        break;
+                ret = at32_wdt_settimeout(time);
+                if (ret)
+                        break;
+                /* Enable new time value */
+                at32_wdt_start();
+                /* fall through */
+        case WDIOC_GETTIMEOUT:
+                ret = put_user(wdt->timeout, p);
+                break;
+        case WDIOC_GETSTATUS: /* fall through */
+        case WDIOC_GETBOOTSTATUS:
+                ret = put_user(0, p);
+                break;
+        case WDIOC_SETOPTIONS:
+                ret = get_user(time, p);
+                if (ret)
+                        break;
+                if (time & WDIOS_DISABLECARD)
+                        at32_wdt_stop();
+                if (time & WDIOS_ENABLECARD)
+                        at32_wdt_start();
+                ret = 0;
+                break;
+        }
+
+        return ret;
+}
+
+static ssize_t at32_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
+{
+        at32_wdt_pat();
+        return len;
+}
+
+static const struct file_operations at32_wdt_fops = {
+        .owner          = THIS_MODULE,
+        .llseek         = no_llseek,
+        .ioctl          = at32_wdt_ioctl,
+        .open           = at32_wdt_open,
+        .release        = at32_wdt_close,
+        .write          = at32_wdt_write,
+};
+
+static int __init at32_wdt_probe(struct platform_device *pdev)
+{
+        struct resource *regs;
+        int ret;
+
+        if (wdt) {
+                dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n");
+                return -EBUSY;
+        }
+
+        regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (!regs) {
+                dev_dbg(&pdev->dev, "missing mmio resource\n");
+                return -ENXIO;
+        }
+
+        wdt = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL);
+        if (!wdt) {
+                dev_dbg(&pdev->dev, "no memory for wdt structure\n");
+                return -ENOMEM;
+        }
+
+        wdt->regs = ioremap(regs->start, regs->end - regs->start + 1);
+        wdt->users = 0;
+        wdt->miscdev.minor = WATCHDOG_MINOR;
+        wdt->miscdev.name = "watchdog";
+        wdt->miscdev.fops = &at32_wdt_fops;
+
+        if (at32_wdt_settimeout(TIMEOUT_DEFAULT)) {
+                at32_wdt_settimeout(TIMEOUT_MAX);
+                dev_dbg(&pdev->dev,
+                        "default timeout invalid, set to %d sec.\n",
+                        TIMEOUT_MAX);
+        }
+
+        ret = misc_register(&wdt->miscdev);
+        if (ret) {
+                dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
+                goto err_register;
+        }
+
+        platform_set_drvdata(pdev, wdt);
+        wdt->miscdev.parent = &pdev->dev;
+        dev_info(&pdev->dev, "AT32AP700X WDT at 0x%p\n", wdt->regs);
+
+        return 0;
+
+err_register:
+        kfree(wdt);
+        wdt = NULL;
+        return ret;
+}
+
+static int __exit at32_wdt_remove(struct platform_device *pdev)
+{
+        if (wdt && platform_get_drvdata(pdev) == wdt) {
+                misc_deregister(&wdt->miscdev);
+                kfree(wdt);
+                wdt = NULL;
+                platform_set_drvdata(pdev, NULL);
+        }
+
+        return 0;
+}
+
+static void at32_wdt_shutdown(struct platform_device *pdev)
+{
+        at32_wdt_stop();
+}
+
+#ifdef CONFIG_PM
+static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
+{
+        at32_wdt_stop();
+        return 0;
+}
+
+static int at32_wdt_resume(struct platform_device *pdev)
+{
+        if (wdt->users)
+                at32_wdt_start();
+        return 0;
+}
+#endif
+
+static struct platform_driver at32_wdt_driver = {
+        .remove         = __exit_p(at32_wdt_remove),
+#ifdef CONFIG_PM
+        .suspend        = at32_wdt_suspend,
+        .resume         = at32_wdt_resume,
+#endif
+        .driver         = {
+                .name   = "at32_wdt",
+                .owner  = THIS_MODULE,
+        },
+        .shutdown       = at32_wdt_shutdown,
+};
+
+static int __init at32_wdt_init(void)
+{
+        return platform_driver_probe(&at32_wdt_driver, at32_wdt_probe);
+}
+module_init(at32_wdt_init);
+
+static void __exit at32_wdt_exit(void)
+{
+        platform_driver_unregister(&at32_wdt_driver);
+}
+module_exit(at32_wdt_exit);
+
+MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
+MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);