watchdog: Adding support for ARM Primecell SP805 Watchdog
Viresh KUMAR [Wed, 4 Aug 2010 06:14:14 +0000 (11:14 +0530)]
Technical Reference Manual can be found at:
http://infocenter.arm.com/help/topic/com.arm.doc.ddi0270b/DDI0270.pdf

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/Kconfig
drivers/watchdog/Makefile
drivers/watchdog/sp805_wdt.c [new file with mode: 0644]

index 910e09f..4d2992a 100644 (file)
@@ -73,6 +73,13 @@ config WM8350_WATCHDOG
 
 # ARM Architecture
 
+config ARM_SP805_WATCHDOG
+       tristate "ARM SP805 Watchdog"
+       depends on ARM_AMBA
+       help
+         ARM Primecell SP805 Watchdog timer. This will reboot your system when
+         the timeout is reached.
+
 config AT91RM9200_WATCHDOG
        tristate "AT91RM9200 watchdog"
        depends on ARCH_AT91RM9200
index 0010ae5..8374503 100644 (file)
@@ -25,6 +25,7 @@ obj-$(CONFIG_USBPCWATCHDOG) += pcwd_usb.o
 # ALPHA Architecture
 
 # ARM Architecture
+obj-$(CONFIG_ARM_SP805_WATCHDOG) += sp805_wdt.o
 obj-$(CONFIG_AT91RM9200_WATCHDOG) += at91rm9200_wdt.o
 obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o
 obj-$(CONFIG_OMAP_WATCHDOG) += omap_wdt.o
diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
new file mode 100644 (file)
index 0000000..9127eda
--- /dev/null
@@ -0,0 +1,387 @@
+/*
+ * drivers/char/watchdog/sp805-wdt.c
+ *
+ * Watchdog driver for ARM SP805 watchdog module
+ *
+ * Copyright (C) 2010 ST Microelectronics
+ * Viresh Kumar<viresh.kumar@st.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2 or later. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/device.h>
+#include <linux/resource.h>
+#include <linux/amba/bus.h>
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/math64.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+#include <linux/watchdog.h>
+
+/* default timeout in seconds */
+#define DEFAULT_TIMEOUT                60
+
+#define MODULE_NAME            "sp805-wdt"
+
+/* watchdog register offsets and masks */
+#define WDTLOAD                        0x000
+       #define LOAD_MIN        0x00000001
+       #define LOAD_MAX        0xFFFFFFFF
+#define WDTVALUE               0x004
+#define WDTCONTROL             0x008
+       /* control register masks */
+       #define INT_ENABLE      (1 << 0)
+       #define RESET_ENABLE    (1 << 1)
+#define WDTINTCLR              0x00C
+#define WDTRIS                 0x010
+#define WDTMIS                 0x014
+       #define INT_MASK        (1 << 0)
+#define WDTLOCK                        0xC00
+       #define UNLOCK          0x1ACCE551
+       #define LOCK            0x00000001
+
+/**
+ * struct sp805_wdt: sp805 wdt device structure
+ *
+ * lock: spin lock protecting dev structure and io access
+ * base: base address of wdt
+ * clk: clock structure of wdt
+ * dev: amba device structure of wdt
+ * status: current status of wdt
+ * load_val: load value to be set for current timeout
+ * timeout: current programmed timeout
+ */
+struct sp805_wdt {
+       spinlock_t                      lock;
+       void __iomem                    *base;
+       struct clk                      *clk;
+       struct amba_device              *adev;
+       unsigned long                   status;
+       #define WDT_BUSY                0
+       #define WDT_CAN_BE_CLOSED       1
+       unsigned int                    load_val;
+       unsigned int                    timeout;
+};
+
+/* local variables */
+static struct sp805_wdt *wdt;
+static int nowayout = WATCHDOG_NOWAYOUT;
+
+/* This routine finds load value that will reset system in required timout */
+static void wdt_setload(unsigned int timeout)
+{
+       u64 load, rate;
+
+       rate = clk_get_rate(wdt->clk);
+
+       /*
+        * sp805 runs counter with given value twice, after the end of first
+        * counter it gives an interrupt and then starts counter again. If
+        * interrupt already occured then it resets the system. This is why
+        * load is half of what should be required.
+        */
+       load = div_u64(rate, 2) * timeout - 1;
+
+       load = (load > LOAD_MAX) ? LOAD_MAX : load;
+       load = (load < LOAD_MIN) ? LOAD_MIN : load;
+
+       spin_lock(&wdt->lock);
+       wdt->load_val = load;
+       /* roundup timeout to closest positive integer value */
+       wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
+       spin_unlock(&wdt->lock);
+}
+
+/* returns number of seconds left for reset to occur */
+static u32 wdt_timeleft(void)
+{
+       u64 load, rate;
+
+       rate = clk_get_rate(wdt->clk);
+
+       spin_lock(&wdt->lock);
+       load = readl(wdt->base + WDTVALUE);
+
+       /*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
+       if (!(readl(wdt->base + WDTRIS) & INT_MASK))
+               load += wdt->load_val + 1;
+       spin_unlock(&wdt->lock);
+
+       return div_u64(load, rate);
+}
+
+/* enables watchdog timers reset */
+static void wdt_enable(void)
+{
+       spin_lock(&wdt->lock);
+
+       writel(UNLOCK, wdt->base + WDTLOCK);
+       writel(wdt->load_val, wdt->base + WDTLOAD);
+       writel(INT_MASK, wdt->base + WDTINTCLR);
+       writel(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
+       writel(LOCK, wdt->base + WDTLOCK);
+
+       spin_unlock(&wdt->lock);
+}
+
+/* disables watchdog timers reset */
+static void wdt_disable(void)
+{
+       spin_lock(&wdt->lock);
+
+       writel(UNLOCK, wdt->base + WDTLOCK);
+       writel(0, wdt->base + WDTCONTROL);
+       writel(0, wdt->base + WDTLOAD);
+       writel(LOCK, wdt->base + WDTLOCK);
+
+       spin_unlock(&wdt->lock);
+}
+
+static ssize_t sp805_wdt_write(struct file *file, const char *data,
+               size_t len, loff_t *ppos)
+{
+       if (len) {
+               if (!nowayout) {
+                       size_t i;
+
+                       clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
+
+                       for (i = 0; i != len; i++) {
+                               char c;
+
+                               if (get_user(c, data + i))
+                                       return -EFAULT;
+                               /* Check for Magic Close character */
+                               if (c == 'V') {
+                                       set_bit(WDT_CAN_BE_CLOSED,
+                                                       &wdt->status);
+                                       break;
+                               }
+                       }
+               }
+               wdt_enable();
+       }
+       return len;
+}
+
+static const struct watchdog_info ident = {
+       .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+       .identity = MODULE_NAME,
+};
+
+static long sp805_wdt_ioctl(struct file *file, unsigned int cmd,
+               unsigned long arg)
+{
+       int ret = -ENOTTY;
+       unsigned int timeout;
+
+       switch (cmd) {
+       case WDIOC_GETSUPPORT:
+               ret = copy_to_user((struct watchdog_info *)arg, &ident,
+                               sizeof(ident)) ? -EFAULT : 0;
+               break;
+
+       case WDIOC_GETSTATUS:
+               ret = put_user(0, (int *)arg);
+               break;
+
+       case WDIOC_KEEPALIVE:
+               wdt_enable();
+               ret = 0;
+               break;
+
+       case WDIOC_SETTIMEOUT:
+               ret = get_user(timeout, (unsigned int *)arg);
+               if (ret)
+                       break;
+
+               wdt_setload(timeout);
+
+               wdt_enable();
+               /* Fall through */
+
+       case WDIOC_GETTIMEOUT:
+               ret = put_user(wdt->timeout, (unsigned int *)arg);
+               break;
+       case WDIOC_GETTIMELEFT:
+               ret = put_user(wdt_timeleft(), (unsigned int *)arg);
+               break;
+       }
+       return ret;
+}
+
+static int sp805_wdt_open(struct inode *inode, struct file *file)
+{
+       int ret = 0;
+
+       if (test_and_set_bit(WDT_BUSY, &wdt->status))
+               return -EBUSY;
+
+       ret = clk_enable(wdt->clk);
+       if (ret) {
+               dev_err(&wdt->adev->dev, "clock enable fail");
+               goto err;
+       }
+
+       wdt_enable();
+
+       /* can not be closed, once enabled */
+       clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
+       return nonseekable_open(inode, file);
+
+err:
+       clear_bit(WDT_BUSY, &wdt->status);
+       return ret;
+}
+
+static int sp805_wdt_release(struct inode *inode, struct file *file)
+{
+       if (!test_bit(WDT_CAN_BE_CLOSED, &wdt->status)) {
+               clear_bit(WDT_BUSY, &wdt->status);
+               dev_warn(&wdt->adev->dev, "Device closed unexpectedly\n");
+               return 0;
+       }
+
+       wdt_disable();
+       clk_disable(wdt->clk);
+       clear_bit(WDT_BUSY, &wdt->status);
+
+       return 0;
+}
+
+static const struct file_operations sp805_wdt_fops = {
+       .owner = THIS_MODULE,
+       .llseek = no_llseek,
+       .write = sp805_wdt_write,
+       .unlocked_ioctl = sp805_wdt_ioctl,
+       .open = sp805_wdt_open,
+       .release = sp805_wdt_release,
+};
+
+static struct miscdevice sp805_wdt_miscdev = {
+       .minor = WATCHDOG_MINOR,
+       .name = "watchdog",
+       .fops = &sp805_wdt_fops,
+};
+
+static int __devinit
+sp805_wdt_probe(struct amba_device *adev, struct amba_id *id)
+{
+       int ret = 0;
+
+       if (!request_mem_region(adev->res.start, resource_size(&adev->res),
+                               "sp805_wdt")) {
+               dev_warn(&adev->dev, "Failed to get memory region resource\n");
+               ret = -ENOENT;
+               goto err;
+       }
+
+       wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
+       if (!wdt) {
+               dev_warn(&adev->dev, "Kzalloc failed\n");
+               ret = -ENOMEM;
+               goto err_kzalloc;
+       }
+
+       wdt->clk = clk_get(&adev->dev, NULL);
+       if (IS_ERR(wdt->clk)) {
+               dev_warn(&adev->dev, "Clock not found\n");
+               ret = PTR_ERR(wdt->clk);
+               goto err_clk_get;
+       }
+
+       wdt->base = ioremap(adev->res.start, resource_size(&adev->res));
+       if (!wdt->base) {
+               ret = -ENOMEM;
+               dev_warn(&adev->dev, "ioremap fail\n");
+               goto err_ioremap;
+       }
+
+       wdt->adev = adev;
+       spin_lock_init(&wdt->lock);
+       wdt_setload(DEFAULT_TIMEOUT);
+
+       ret = misc_register(&sp805_wdt_miscdev);
+       if (ret < 0) {
+               dev_warn(&adev->dev, "cannot register misc device\n");
+               goto err_misc_register;
+       }
+
+       dev_info(&adev->dev, "registration successful\n");
+       return 0;
+
+err_misc_register:
+       iounmap(wdt->base);
+err_ioremap:
+       clk_put(wdt->clk);
+err_clk_get:
+       kfree(wdt);
+       wdt = NULL;
+err_kzalloc:
+       release_mem_region(adev->res.start, resource_size(&adev->res));
+err:
+       dev_err(&adev->dev, "Probe Failed!!!\n");
+       return ret;
+}
+
+static int __devexit sp805_wdt_remove(struct amba_device *adev)
+{
+       misc_deregister(&sp805_wdt_miscdev);
+       iounmap(wdt->base);
+       clk_put(wdt->clk);
+       kfree(wdt);
+       release_mem_region(adev->res.start, resource_size(&adev->res));
+
+       return 0;
+}
+
+static struct amba_id sp805_wdt_ids[] __initdata = {
+       {
+               .id     = 0x00141805,
+               .mask   = 0x00ffffff,
+       },
+       { 0, 0 },
+};
+
+static struct amba_driver sp805_wdt_driver = {
+       .drv = {
+               .name   = MODULE_NAME,
+       },
+       .id_table       = sp805_wdt_ids,
+       .probe          = sp805_wdt_probe,
+       .remove = __devexit_p(sp805_wdt_remove),
+};
+
+static int __init sp805_wdt_init(void)
+{
+       return amba_driver_register(&sp805_wdt_driver);
+}
+module_init(sp805_wdt_init);
+
+static void __exit sp805_wdt_exit(void)
+{
+       amba_driver_unregister(&sp805_wdt_driver);
+}
+module_exit(sp805_wdt_exit);
+
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout,
+               "Set to 1 to keep watchdog running after device release");
+
+MODULE_AUTHOR("Viresh Kumar <viresh.kumar@st.com>");
+MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);