watchdog: Adding support for ARM Primecell SP805 Watchdog

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>

1 files changed, 387 insertions, 0 deletions

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@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);