[WATCHDOG] support for max63xx watchdog timer chips

This driver adds support for the max63{69,70,71,72,73,74} family of
watchdog timer chips.

It has been tested on an Arcom Zeus (max6369).

Signed-off-by: Marc Zyngier <maz@misterjones.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

3 files changed, 403 insertions, 0 deletions

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 1e48d4c45f86..713b1cef37d3 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -55,6 +55,11 @@ config SOFT_WATCHDOG
           To compile this driver as a module, choose M here: the
           module will be called softdog.
 
+config MAX63XX_WATCHDOG
+       tristate "Max63xx watchdog"
+       help
+         Support for memory mapped max63{69,70,71,72,73,74} watchdog timer.
+
 config WM831X_WATCHDOG
         tristate "WM831x watchdog"
         depends on MFD_WM831X
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 2fd15947deb7..5e3cb95bb0e9 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -143,4 +143,5 @@ obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
 # Architecture Independant
 obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
 obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
+obj-$(CONFIG_MAX63XX_WATCHDOG) += max63xx_wdt.o
 obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
diff --git a/drivers/watchdog/max63xx_wdt.c b/drivers/watchdog/max63xx_wdt.c
new file mode 100644
index 000000000000..6eb91d757604
--- /dev/null
+++ b/drivers/watchdog/max63xx_wdt.c
@@ -0,0 +1,397 @@
+/*
+ * drivers/char/watchdog/max63xx_wdt.c
+ *
+ * Driver for max63{69,70,71,72,73,74} watchdog timers
+ *
+ * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * This driver assumes the watchdog pins are memory mapped (as it is
+ * the case for the Arcom Zeus). Should it be connected over GPIOs or
+ * another interface, some abstraction will have to be introduced.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/init.h>
+#include <linux/bitops.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <linux/io.h>
+#include <linux/device.h>
+
+#define DEFAULT_HEARTBEAT 60
+#define MAX_HEARTBEAT     60
+
+static int heartbeat = DEFAULT_HEARTBEAT;
+static int nowayout  = WATCHDOG_NOWAYOUT;
+
+/*
+ * Memory mapping: a single byte, 3 first lower bits to select bit 3
+ * to ping the watchdog.
+ */
+#define MAX6369_WDSET   (7 << 0)
+#define MAX6369_WDI     (1 << 3)
+
+static DEFINE_SPINLOCK(io_lock);
+
+static unsigned long wdt_status;
+#define WDT_IN_USE      0
+#define WDT_RUNNING     1
+#define WDT_OK_TO_CLOSE 2
+
+static int nodelay;
+static struct resource  *wdt_mem;
+static void __iomem     *wdt_base;
+static struct platform_device *max63xx_pdev;
+
+/*
+ * The timeout values used are actually the absolute minimum the chip
+ * offers. Typical values on my board are slightly over twice as long
+ * (10s setting ends up with a 25s timeout), and can be up to 3 times
+ * the nominal setting (according to the datasheet). So please take
+ * these values with a grain of salt. Same goes for the initial delay
+ * "feature". Only max6373/74 have a few settings without this initial
+ * delay (selected with the "nodelay" parameter).
+ *
+ * I also decided to remove from the tables any timeout smaller than a
+ * second, as it looked completly overkill...
+ */
+
+/* Timeouts in second */
+struct max63xx_timeout {
+        u8 wdset;
+        u8 tdelay;
+        u8 twd;
+};
+
+static struct max63xx_timeout max6369_table[] = {
+        { 5,  1,  1 },
+        { 6, 10, 10 },
+        { 7, 60, 60 },
+        { },
+};
+
+static struct max63xx_timeout max6371_table[] = {
+        { 6, 60,  3 },
+        { 7, 60, 60 },
+        { },
+};
+
+static struct max63xx_timeout max6373_table[] = {
+        { 2, 60,  1 },
+        { 5,  0,  1 },
+        { 1,  3,  3 },
+        { 7, 60, 10 },
+        { 6,  0, 10 },
+        { },
+};
+
+static struct max63xx_timeout *current_timeout;
+
+static struct max63xx_timeout *
+max63xx_select_timeout(struct max63xx_timeout *table, int value)
+{
+        while (table->twd) {
+                if (value <= table->twd) {
+                        if (nodelay && table->tdelay == 0)
+                                return table;
+
+                        if (!nodelay)
+                                return table;
+                }
+
+                table++;
+        }
+
+        return NULL;
+}
+
+static void max63xx_wdt_ping(void)
+{
+        u8 val;
+
+        spin_lock(&io_lock);
+
+        val = __raw_readb(wdt_base);
+
+        __raw_writeb(val | MAX6369_WDI, wdt_base);
+        __raw_writeb(val & ~MAX6369_WDI, wdt_base);
+
+        spin_unlock(&io_lock);
+}
+
+static void max63xx_wdt_enable(struct max63xx_timeout *entry)
+{
+        u8 val;
+
+        if (test_and_set_bit(WDT_RUNNING, &wdt_status))
+                return;
+
+        spin_lock(&io_lock);
+
+        val = __raw_readb(wdt_base);
+        val &= ~MAX6369_WDSET;
+        val |= entry->wdset;
+        __raw_writeb(val, wdt_base);
+
+        spin_unlock(&io_lock);
+
+        /* check for a edge triggered startup */
+        if (entry->tdelay == 0)
+                max63xx_wdt_ping();
+}
+
+static void max63xx_wdt_disable(void)
+{
+        spin_lock(&io_lock);
+
+        __raw_writeb(3, wdt_base);
+
+        spin_unlock(&io_lock);
+
+        clear_bit(WDT_RUNNING, &wdt_status);
+}
+
+static int max63xx_wdt_open(struct inode *inode, struct file *file)
+{
+        if (test_and_set_bit(WDT_IN_USE, &wdt_status))
+                return -EBUSY;
+
+        max63xx_wdt_enable(current_timeout);
+        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+
+        return nonseekable_open(inode, file);
+}
+
+static ssize_t max63xx_wdt_write(struct file *file, const char *data,
+                                 size_t len, loff_t *ppos)
+{
+        if (len) {
+                if (!nowayout) {
+                        size_t i;
+
+                        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+                        for (i = 0; i != len; i++) {
+                                char c;
+
+                                if (get_user(c, data + i))
+                                        return -EFAULT;
+
+                                if (c == 'V')
+                                        set_bit(WDT_OK_TO_CLOSE, &wdt_status);
+                        }
+                }
+
+                max63xx_wdt_ping();
+        }
+
+        return len;
+}
+
+static const struct watchdog_info ident = {
+        .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
+        .identity = "max63xx Watchdog",
+};
+
+static long max63xx_wdt_ioctl(struct file *file, unsigned int cmd,
+                              unsigned long arg)
+{
+        int ret = -ENOTTY;
+
+        switch (cmd) {
+        case WDIOC_GETSUPPORT:
+                ret = copy_to_user((struct watchdog_info *)arg, &ident,
+                                   sizeof(ident)) ? -EFAULT : 0;
+                break;
+
+        case WDIOC_GETSTATUS:
+        case WDIOC_GETBOOTSTATUS:
+                ret = put_user(0, (int *)arg);
+                break;
+
+        case WDIOC_KEEPALIVE:
+                max63xx_wdt_ping();
+                ret = 0;
+                break;
+
+        case WDIOC_GETTIMEOUT:
+                ret = put_user(heartbeat, (int *)arg);
+                break;
+        }
+        return ret;
+}
+
+static int max63xx_wdt_release(struct inode *inode, struct file *file)
+{
+        if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
+                max63xx_wdt_disable();
+        else
+                dev_crit(&max63xx_pdev->dev,
+                         "device closed unexpectedly - timer will not stop\n");
+
+        clear_bit(WDT_IN_USE, &wdt_status);
+        clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+
+        return 0;
+}
+
+static const struct file_operations max63xx_wdt_fops = {
+        .owner          = THIS_MODULE,
+        .llseek         = no_llseek,
+        .write          = max63xx_wdt_write,
+        .unlocked_ioctl = max63xx_wdt_ioctl,
+        .open           = max63xx_wdt_open,
+        .release        = max63xx_wdt_release,
+};
+
+static struct miscdevice max63xx_wdt_miscdev = {
+        .minor  = WATCHDOG_MINOR,
+        .name   = "watchdog",
+        .fops   = &max63xx_wdt_fops,
+};
+
+static int __devinit max63xx_wdt_probe(struct platform_device *pdev)
+{
+        int ret = 0;
+        int size;
+        struct resource *res;
+        struct device *dev = &pdev->dev;
+        struct max63xx_timeout *table;
+
+        table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
+
+        if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
+                heartbeat = DEFAULT_HEARTBEAT;
+
+        dev_info(dev, "requesting %ds heartbeat\n", heartbeat);
+        current_timeout = max63xx_select_timeout(table, heartbeat);
+
+        if (!current_timeout) {
+                dev_err(dev, "unable to satisfy heartbeat request\n");
+                return -EINVAL;
+        }
+
+        dev_info(dev, "using %ds heartbeat with %ds initial delay\n",
+                 current_timeout->twd, current_timeout->tdelay);
+
+        heartbeat = current_timeout->twd;
+
+        max63xx_pdev = pdev;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (res == NULL) {
+                dev_err(dev, "failed to get memory region resource\n");
+                return -ENOENT;
+        }
+
+        size = resource_size(res);
+        wdt_mem = request_mem_region(res->start, size, pdev->name);
+
+        if (wdt_mem == NULL) {
+                dev_err(dev, "failed to get memory region\n");
+                return -ENOENT;
+        }
+
+        wdt_base = ioremap(res->start, size);
+        if (!wdt_base) {
+                dev_err(dev, "failed to map memory region\n");
+                ret = -ENOMEM;
+                goto out_request;
+        }
+
+        ret = misc_register(&max63xx_wdt_miscdev);
+        if (ret < 0) {
+                dev_err(dev, "cannot register misc device\n");
+                goto out_unmap;
+        }
+
+        return 0;
+
+out_unmap:
+        iounmap(wdt_base);
+out_request:
+        release_resource(wdt_mem);
+        kfree(wdt_mem);
+
+        return ret;
+}
+
+static int __devexit max63xx_wdt_remove(struct platform_device *pdev)
+{
+        misc_deregister(&max63xx_wdt_miscdev);
+        if (wdt_mem) {
+                release_resource(wdt_mem);
+                kfree(wdt_mem);
+                wdt_mem = NULL;
+        }
+
+        if (wdt_base)
+                iounmap(wdt_base);
+
+        return 0;
+}
+
+static struct platform_device_id max63xx_id_table[] = {
+        { "max6369_wdt", (kernel_ulong_t)max6369_table, },
+        { "max6370_wdt", (kernel_ulong_t)max6369_table, },
+        { "max6371_wdt", (kernel_ulong_t)max6371_table, },
+        { "max6372_wdt", (kernel_ulong_t)max6371_table, },
+        { "max6373_wdt", (kernel_ulong_t)max6373_table, },
+        { "max6374_wdt", (kernel_ulong_t)max6373_table, },
+        { },
+};
+MODULE_DEVICE_TABLE(platform, max63xx_id_table);
+
+static struct platform_driver max63xx_wdt_driver = {
+        .probe          = max63xx_wdt_probe,
+        .remove         = __devexit_p(max63xx_wdt_remove),
+        .id_table       = max63xx_id_table,
+        .driver         = {
+                .name   = "max63xx_wdt",
+                .owner  = THIS_MODULE,
+        },
+};
+
+static int __init max63xx_wdt_init(void)
+{
+        return platform_driver_register(&max63xx_wdt_driver);
+}
+
+static void __exit max63xx_wdt_exit(void)
+{
+        platform_driver_unregister(&max63xx_wdt_driver);
+}
+
+module_init(max63xx_wdt_init);
+module_exit(max63xx_wdt_exit);
+
+MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
+MODULE_DESCRIPTION("max63xx Watchdog Driver");
+
+module_param(heartbeat, int, 0);
+MODULE_PARM_DESC(heartbeat,
+                 "Watchdog heartbeat period in seconds from 1 to "
+                 __MODULE_STRING(MAX_HEARTBEAT) ", default "
+                 __MODULE_STRING(DEFAULT_HEARTBEAT));
+
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+module_param(nodelay, int, 0);
+MODULE_PARM_DESC(nodelay,
+                 "Force selection of a timeout setting without initial delay "
+                 "(max6373/74 only, default=0)");
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);