[PATCH] Watchdog: Adding support for Watchdog found with ARM CortexA9

Viresh KUMAR viresh.kumar at st.com
Mon May 17 05:54:04 EDT 2010


Watchdog details can be found in ARM Cortex A9 reference manual at:
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0407e/indix.html

Signed-off-by: Viresh Kumar <viresh.kumar at st.com>
---
 drivers/watchdog/Kconfig        |    7 +
 drivers/watchdog/Makefile       |    1 +
 drivers/watchdog/cortexa9_wdt.c |  414 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 422 insertions(+), 0 deletions(-)
 create mode 100755 drivers/watchdog/cortexa9_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 0bf5020..b5c0f6f 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -73,6 +73,13 @@ config WM8350_WATCHDOG
 
 # ARM Architecture
 
+config ARM_CORTEXA9_WATCHDOG
+	tristate "ARM CortexA9 Watchdog"
+	depends on ARM_AMBA
+	help
+	  Watchdog timer present with ARM Cortex A9 processor. 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 5e3cb95..7704efc 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_USBPCWATCHDOG) += pcwd_usb.o
 # ALPHA Architecture
 
 # ARM Architecture
+obj-$(CONFIG_ARM_CORTEXA9_WATCHDOG) += cortexa9_wdt.o
 obj-$(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/cortexa9_wdt.c b/drivers/watchdog/cortexa9_wdt.c
new file mode 100755
index 0000000..f50ec64
--- /dev/null
+++ b/drivers/watchdog/cortexa9_wdt.c
@@ -0,0 +1,414 @@
+/*
+ * drivers/char/watchdog/cortexa9-wdt.c
+ *
+ * Watchdog driver for watchdog module present with ARM CORTEX A9
+ *
+ * Copyright (C) 2010 ST Microelectronics
+ * Viresh Kumar<viresh.kumar at st.com>
+ *
+ * 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.
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/device.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/platform_device.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		"cortexa9-wdt"
+
+/* watchdog register offsets and masks */
+#define WDTLOAD			0x000
+	#define LOAD_MIN	0x00000000
+	#define LOAD_MAX	0xFFFFFFFF
+#define WDTCOUNTER		0x004
+#define WDTCONTROL		0x008
+	/* control register masks */
+	#define WDT_ENB		(1 << 0)
+	#define WDT_ARLD_ENB	(1 << 1)	/* Autoreload enable */
+	#define WDT_IRQ_ENB	(1 << 2)
+	#define WDT_MODE	(1 << 3)
+	#define WDT_PRESCALE(x)	((x) << 8)
+	#define PRESCALE_MIN	0x00
+	#define PRESCALE_MAX	0xFF
+#define WDTINTSTS		0x00C
+	#define INT_MASK	0x1
+#define WDTRSTSTS		0x010
+	#define RST_MASK	0x1
+#define WDTDISABLE		0x014
+	#define DISABLE_VAL1	0x12345678
+	#define DISABLE_VAL2	0x87654321
+
+/**
+ * struct cortexa9_wdt: cortex a9 wdt device structure
+ *
+ * lock: spin lock protecting dev structure and io access
+ * base: base address of wdt
+ * clk: clock structure of wdt
+ * pdev: platform device structure of wdt
+ * boot_status: boot time status of wdt
+ * status: current status of wdt
+ * prescale: prescale value to be set for current timeout
+ * load_val: load value to be set for current timeout
+ * timeout: current programmed timeout
+ */
+struct cortexa9_wdt {
+	spinlock_t			lock;
+	void __iomem			*base;
+	struct clk			*clk;
+	struct platform_device		*pdev;
+	unsigned long			boot_status;
+	unsigned long			status;
+	#define WDT_BUSY		0
+	#define WDT_CAN_BE_CLOSED	1
+	unsigned int			prescale;
+	unsigned int			load_val;
+	unsigned int			timeout;
+};
+
+/* local variables */
+static struct cortexa9_wdt *wdt;
+static int nowayout = WATCHDOG_NOWAYOUT;
+
+/* binary search */
+static inline void bsearch(u32 *var, u32 var_start, u32 var_end,
+		const u64 param, const u32 timeout, u32 rate)
+{
+	u64 tmp = 0;
+
+	/* get the lowest var value that can satisfy our requirement */
+	while (var_start < var_end) {
+		tmp = var_start;
+		tmp += var_end;
+		tmp = div_u64(tmp, 2);
+		if (timeout > div_u64((param + 1) * (tmp + 1), rate)) {
+			if (var_start == tmp)
+				break;
+			else
+				var_start = tmp;
+		} else {
+			if (var_end == tmp)
+				break;
+			else
+				var_end = tmp;
+		}
+	}
+	*var = tmp;
+}
+
+/*
+ * This routine finds the most appropriate prescale and load value for input
+ * timout value
+ */
+static void wdt_config(unsigned int timeout)
+{
+	unsigned int psc, rate;
+	u64 load = 0;
+
+	rate = clk_get_rate(wdt->clk);
+
+	/* get appropriate value of psc and load */
+	bsearch(&psc, PRESCALE_MIN, PRESCALE_MAX, LOAD_MAX, timeout, rate);
+	bsearch((u32 *)&load, LOAD_MIN, LOAD_MAX, psc, timeout, rate);
+
+	spin_lock(&wdt->lock);
+	wdt->prescale = psc;
+	wdt->load_val = load;
+
+	/* roundup timeout to closest positive integer value */
+	wdt->timeout = div_u64((psc + 1) * (load + 1) + (rate / 2), rate);
+	spin_unlock(&wdt->lock);
+}
+
+static void wdt_enable(void)
+{
+	u32 val;
+
+	spin_lock(&wdt->lock);
+
+	writel(wdt->load_val, wdt->base + WDTLOAD);
+	val = WDT_MODE | WDT_PRESCALE(wdt->prescale) | WDT_ENB;
+	writel(val, wdt->base + WDTCONTROL);
+
+	spin_unlock(&wdt->lock);
+}
+
+static void wdt_disable(void)
+{
+	spin_lock(&wdt->lock);
+
+	/* firstly we need to put watchdog in timer mode */
+	writel(DISABLE_VAL1, wdt->base + WDTDISABLE);
+	writel(DISABLE_VAL2, wdt->base + WDTDISABLE);
+
+	writel(0, wdt->base + WDTCONTROL);
+	writel(INT_MASK, wdt->base + WDTINTSTS);
+	writel(RST_MASK, wdt->base + WDTRSTSTS);
+
+	spin_unlock(&wdt->lock);
+}
+
+static ssize_t cortexa9_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;
+				if (c == 'V') {
+					set_bit(WDT_CAN_BE_CLOSED,
+							&wdt->status);
+					break;
+				}
+			}
+		}
+		wdt_enable();
+	}
+	return len;
+}
+
+static const struct watchdog_info ident = {
+	.options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
+		WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+	.identity = MODULE_NAME,
+};
+
+static long cortexa9_wdt_ioctl(struct file *file, unsigned int cmd,
+		unsigned long arg)
+{
+	int ret = -ENOTTY;
+	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_GETBOOTSTATUS:
+		ret = put_user(wdt->boot_status, (int *)arg);
+		break;
+
+	case WDIOC_KEEPALIVE:
+		wdt_enable();
+		ret = 0;
+		break;
+
+	case WDIOC_SETTIMEOUT:
+		ret = get_user(timeout, (int *)arg);
+		if (ret)
+			break;
+
+		wdt_config(timeout);
+
+		wdt_enable();
+		/* Fall through */
+
+	case WDIOC_GETTIMEOUT:
+		ret = put_user(wdt->timeout, (int *)arg);
+		break;
+	}
+	return ret;
+}
+
+static int cortexa9_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->pdev->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 cortexa9_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->pdev->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 cortexa9_wdt_fops = {
+	.owner = THIS_MODULE,
+	.llseek = no_llseek,
+	.write = cortexa9_wdt_write,
+	.unlocked_ioctl = cortexa9_wdt_ioctl,
+	.open = cortexa9_wdt_open,
+	.release = cortexa9_wdt_release,
+};
+
+static struct miscdevice cortexa9_wdt_miscdev = {
+	.minor = WATCHDOG_MINOR,
+	.name = "watchdog",
+	.fops = &cortexa9_wdt_fops,
+};
+
+static int __devinit cortexa9_wdt_probe(struct platform_device *pdev)
+{
+	int ret = 0;
+	struct resource *res;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		ret = -ENOENT;
+		dev_warn(&pdev->dev, "Memory resource not defined\n");
+		goto err;
+	}
+
+	if (!request_mem_region(res->start, resource_size(res), pdev->name)) {
+		dev_warn(&pdev->dev, "Failed to get memory region resource\n");
+		ret = -ENOENT;
+		goto err;
+	}
+
+	wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
+	if (!wdt) {
+		dev_warn(&pdev->dev, "Kzalloc failed\n");
+		ret = -ENOMEM;
+		goto err_kzalloc;
+	}
+
+	wdt->clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(wdt->clk)) {
+		dev_warn(&pdev->dev, "Clock not found\n");
+		ret = PTR_ERR(wdt->clk);
+		goto err_clk_get;
+	}
+
+	wdt->base = ioremap(res->start, resource_size(res));
+	if (!wdt->base) {
+		ret = -ENOMEM;
+		dev_warn(&pdev->dev, "ioremap fail\n");
+		goto err_ioremap;
+	}
+
+	spin_lock_init(&wdt->lock);
+	/* This checks if system booted after watchdog reset or not */
+	ret = clk_enable(wdt->clk);
+	if (!ret) {
+		wdt->boot_status = (readl(wdt->base + WDTRSTSTS) & RST_MASK) ?
+			WDIOF_CARDRESET : 0;
+		wdt_disable();
+		clk_disable(wdt->clk);
+	}
+
+	wdt->pdev = pdev;
+	wdt_config(DEFAULT_TIMEOUT);
+
+	ret = misc_register(&cortexa9_wdt_miscdev);
+	if (ret < 0) {
+		dev_warn(&pdev->dev, "cannot register misc device\n");
+		goto err_misc_register;
+	}
+
+	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(res->start, resource_size(res));
+err:
+	dev_err(&pdev->dev, "Probe Failed!!!\n");
+	return ret;
+}
+
+static int __devexit cortexa9_wdt_remove(struct platform_device *pdev)
+{
+	struct resource *res;
+
+	misc_deregister(&cortexa9_wdt_miscdev);
+	iounmap(wdt->base);
+	clk_put(wdt->clk);
+	kfree(wdt);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res)
+		release_mem_region(res->start, resource_size(res));
+
+	return 0;
+}
+
+static struct platform_driver cortexa9_wdt_driver = {
+	.driver = {
+		.name = MODULE_NAME,
+		.owner	= THIS_MODULE,
+	},
+	.probe = cortexa9_wdt_probe,
+	.remove = __devexit_p(cortexa9_wdt_remove),
+};
+
+static int __init cortexa9_wdt_init(void)
+{
+	return platform_driver_register(&cortexa9_wdt_driver);
+}
+module_init(cortexa9_wdt_init);
+
+static void __exit cortexa9_wdt_exit(void)
+{
+	platform_driver_unregister(&cortexa9_wdt_driver);
+}
+module_exit(cortexa9_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 at st.com>");
+MODULE_DESCRIPTION("ARM CORTEX A9 Watchdog Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
-- 
1.6.0.2




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