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From: Viresh KUMAR on 4 Aug 2010 02:20
Technical Reference Manual can be found at:
http://infocenter.arm.com/help/topic/com.arm.doc.ddi0270b/DDI0270.pdf

Modifications in V2:
- Included slab.h in sp805_wdt.c

Signed-off-by: Viresh Kumar <viresh.kumar(a)st.com>
---
drivers/watchdog/Kconfig | 7 +
drivers/watchdog/Makefile | 1 +
drivers/watchdog/sp805_wdt.c | 387 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 395 insertions(+), 0 deletions(-)
create mode 100644 drivers/watchdog/sp805_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index afcfacc..6eb311a 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -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
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 72f3e20..d69c24b 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -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
index 0000000..9127eda
--- /dev/null
+++ b/drivers/watchdog/sp805_wdt.c
@@ -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(a)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(a)st.com>");
+MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
--
1.6.0.2

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Prev: Using Bootmem for large DMA buffers in the presence of the slab allocator
Next: Input updates for 2.6.34-rc6