[WATCHDOG] Add watchdog driver for NUC900

Add watchdog device driver for the Nuvoton NUC900 series SoCs.
Signed-off-by: NWan ZongShun <mcuos.com@gmail.com>
Signed-off-by: NWim Van Sebroeck <wim@iguana.be>

drivers/watchdog/Kconfig

@@ -266,6 +266,15 @@ config STMP3XXX_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called stmp3xxx_wdt.
 
+config NUC900_WATCHDOG
+	tristate "Nuvoton NUC900 watchdog"
+	depends on ARCH_W90X900
+	help
+	  Say Y here if to include support for the watchdog timer
+	  for the Nuvoton NUC900 series SoCs.
+	  To compile this driver as a module, choose M here: the
+	  module will be called nuc900_wdt.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT

drivers/watchdog/Makefile

@@ -44,6 +44,7 @@ obj-$(CONFIG_DAVINCI_WATCHDOG) += davinci_wdt.o
 obj-$(CONFIG_ORION_WATCHDOG) += orion_wdt.o
 obj-$(CONFIG_COH901327_WATCHDOG) += coh901327_wdt.o
 obj-$(CONFIG_STMP3XXX_WATCHDOG) += stmp3xxx_wdt.o
+obj-$(CONFIG_NUC900_WATCHDOG) += nuc900_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o

drivers/watchdog/nuc900_wdt.c

+/*
+ * Copyright (c) 2009 Nuvoton technology corporation.
+ *
+ * Wan ZongShun <mcuos.com@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation;version 2 of the License.
+ *
+ */
+
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+#include <linux/uaccess.h>
+
+#define REG_WTCR		0x1c
+#define WTCLK			(0x01 << 10)
+#define WTE			(0x01 << 7)	/*wdt enable*/
+#define WTIS			(0x03 << 4)
+#define WTIF			(0x01 << 3)
+#define WTRF			(0x01 << 2)
+#define WTRE			(0x01 << 1)
+#define WTR			(0x01 << 0)
+/*
+ * The watchdog time interval can be calculated via following formula:
+ * WTIS		real time interval (formula)
+ * 0x00		((2^ 14 ) * ((external crystal freq) / 256))seconds
+ * 0x01		((2^ 16 ) * ((external crystal freq) / 256))seconds
+ * 0x02		((2^ 18 ) * ((external crystal freq) / 256))seconds
+ * 0x03		((2^ 20 ) * ((external crystal freq) / 256))seconds
+ *
+ * The external crystal freq is 15Mhz in the nuc900 evaluation board.
+ * So 0x00 = +-0.28 seconds, 0x01 = +-1.12 seconds, 0x02 = +-4.48 seconds,
+ * 0x03 = +- 16.92 seconds..
+ */
+#define WDT_HW_TIMEOUT		0x02
+#define WDT_TIMEOUT		(HZ/2)
+#define WDT_HEARTBEAT		15
+
+static int heartbeat = WDT_HEARTBEAT;
+module_param(heartbeat, int, 0);
+MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
+	"(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
+	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+struct nuc900_wdt {
+	struct resource  *res;
+	struct clk	 *wdt_clock;
+	struct platform_device *pdev;
+	void __iomem	 *wdt_base;
+	char		 expect_close;
+	struct timer_list timer;
+	spinlock_t       wdt_lock;
+	unsigned long next_heartbeat;
+};
+
+static unsigned long nuc900wdt_busy;
+struct nuc900_wdt *nuc900_wdt;
+
+static inline void nuc900_wdt_keepalive(void)
+{
+	unsigned int val;
+
+	spin_lock(&nuc900_wdt->wdt_lock);
+
+	val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
+	val |= (WTR | WTIF);
+	__raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
+
+	spin_unlock(&nuc900_wdt->wdt_lock);
+}
+
+static inline void nuc900_wdt_start(void)
+{
+	unsigned int val;
+
+	spin_lock(&nuc900_wdt->wdt_lock);
+
+	val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
+	val |= (WTRE | WTE | WTR | WTCLK | WTIF);
+	val &= ~WTIS;
+	val |= (WDT_HW_TIMEOUT << 0x04);
+	__raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
+
+	spin_unlock(&nuc900_wdt->wdt_lock);
+
+	nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
+	mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
+}
+
+static inline void nuc900_wdt_stop(void)
+{
+	unsigned int val;
+
+	del_timer(&nuc900_wdt->timer);
+
+	spin_lock(&nuc900_wdt->wdt_lock);
+
+	val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
+	val &= ~WTE;
+	__raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
+
+	spin_unlock(&nuc900_wdt->wdt_lock);
+}
+
+static inline void nuc900_wdt_ping(void)
+{
+	nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
+}
+
+static int nuc900_wdt_open(struct inode *inode, struct file *file)
+{
+
+	if (test_and_set_bit(0, &nuc900wdt_busy))
+		return -EBUSY;
+
+	nuc900_wdt_start();
+
+	return nonseekable_open(inode, file);
+}
+
+static int nuc900_wdt_close(struct inode *inode, struct file *file)
+{
+	if (nuc900_wdt->expect_close == 42)
+		nuc900_wdt_stop();
+	else {
+		dev_crit(&nuc900_wdt->pdev->dev,
+			"Unexpected close, not stopping watchdog!\n");
+		nuc900_wdt_ping();
+	}
+
+	nuc900_wdt->expect_close = 0;
+	clear_bit(0, &nuc900wdt_busy);
+	return 0;
+}
+
+static const struct watchdog_info nuc900_wdt_info = {
+	.identity	= "nuc900 watchdog",
+	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
+						WDIOF_MAGICCLOSE,
+};
+
+static long nuc900_wdt_ioctl(struct file *file,
+					unsigned int cmd, unsigned long arg)
+{
+	void __user *argp = (void __user *)arg;
+	int __user *p = argp;
+	int new_value;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		return copy_to_user(argp, &nuc900_wdt_info,
+				sizeof(nuc900_wdt_info)) ? -EFAULT : 0;
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		return put_user(0, p);
+
+	case WDIOC_KEEPALIVE:
+		nuc900_wdt_ping();
+		return 0;
+
+	case WDIOC_SETTIMEOUT:
+		if (get_user(new_value, p))
+			return -EFAULT;
+
+		heartbeat = new_value;
+		nuc900_wdt_ping();
+
+		return put_user(new_value, p);
+	case WDIOC_GETTIMEOUT:
+		return put_user(heartbeat, p);
+	default:
+		return -ENOTTY;
+	}
+}
+
+static ssize_t nuc900_wdt_write(struct file *file, const char __user *data,
+						size_t len, loff_t *ppos)
+{
+	if (!len)
+		return 0;
+
+	/* Scan for magic character */
+	if (!nowayout) {
+		size_t i;
+
+		nuc900_wdt->expect_close = 0;
+
+		for (i = 0; i < len; i++) {
+			char c;
+			if (get_user(c, data + i))
+				return -EFAULT;
+			if (c == 'V') {
+				nuc900_wdt->expect_close = 42;
+				break;
+			}
+		}
+	}
+
+	nuc900_wdt_ping();
+	return len;
+}
+
+static void nuc900_wdt_timer_ping(unsigned long data)
+{
+	if (time_before(jiffies, nuc900_wdt->next_heartbeat)) {
+		nuc900_wdt_keepalive();
+		mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
+	} else
+		dev_warn(&nuc900_wdt->pdev->dev, "Will reset the machine !\n");
+}
+
+static const struct file_operations nuc900wdt_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.unlocked_ioctl	= nuc900_wdt_ioctl,
+	.open		= nuc900_wdt_open,
+	.release	= nuc900_wdt_close,
+	.write		= nuc900_wdt_write,
+};
+
+static struct miscdevice nuc900wdt_miscdev = {
+	.minor		= WATCHDOG_MINOR,
+	.name		= "watchdog",
+	.fops		= &nuc900wdt_fops,
+};
+
+static int __devinit nuc900wdt_probe(struct platform_device *pdev)
+{
+	int ret = 0;
+
+	nuc900_wdt = kzalloc(sizeof(struct nuc900_wdt), GFP_KERNEL);
+	if (!nuc900_wdt)
+		return -ENOMEM;
+
+	nuc900_wdt->pdev = pdev;
+
+	spin_lock_init(&nuc900_wdt->wdt_lock);
+
+	nuc900_wdt->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (nuc900_wdt->res == NULL) {
+		dev_err(&pdev->dev, "no memory resource specified\n");
+		ret = -ENOENT;
+		goto err_get;
+	}
+
+	if (!request_mem_region(nuc900_wdt->res->start,
+				resource_size(nuc900_wdt->res), pdev->name)) {
+		dev_err(&pdev->dev, "failed to get memory region\n");
+		ret = -ENOENT;
+		goto err_get;
+	}
+
+	nuc900_wdt->wdt_base = ioremap(nuc900_wdt->res->start,
+					resource_size(nuc900_wdt->res));
+	if (nuc900_wdt->wdt_base == NULL) {
+		dev_err(&pdev->dev, "failed to ioremap() region\n");
+		ret = -EINVAL;
+		goto err_req;
+	}
+
+	nuc900_wdt->wdt_clock = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(nuc900_wdt->wdt_clock)) {
+		dev_err(&pdev->dev, "failed to find watchdog clock source\n");
+		ret = PTR_ERR(nuc900_wdt->wdt_clock);
+		goto err_map;
+	}
+
+	clk_enable(nuc900_wdt->wdt_clock);
+
+	setup_timer(&nuc900_wdt->timer, nuc900_wdt_timer_ping, 0);
+
+	if (misc_register(&nuc900wdt_miscdev)) {
+		dev_err(&pdev->dev, "err register miscdev on minor=%d (%d)\n",
+			WATCHDOG_MINOR, ret);
+		goto err_clk;
+	}
+
+	return 0;
+
+err_clk:
+	clk_disable(nuc900_wdt->wdt_clock);
+	clk_put(nuc900_wdt->wdt_clock);
+err_map:
+	iounmap(nuc900_wdt->wdt_base);
+err_req:
+	release_mem_region(nuc900_wdt->res->start,
+					resource_size(nuc900_wdt->res));
+err_get:
+	kfree(nuc900_wdt);
+	return ret;
+}
+
+static int __devexit nuc900wdt_remove(struct platform_device *pdev)
+{
+	misc_deregister(&nuc900wdt_miscdev);
+
+	clk_disable(nuc900_wdt->wdt_clock);
+	clk_put(nuc900_wdt->wdt_clock);
+
+	iounmap(nuc900_wdt->wdt_base);
+
+	release_mem_region(nuc900_wdt->res->start,
+					resource_size(nuc900_wdt->res));
+
+	kfree(nuc900_wdt);
+
+	return 0;
+}
+
+static struct platform_driver nuc900wdt_driver = {
+	.probe		= nuc900wdt_probe,
+	.remove		= __devexit_p(nuc900wdt_remove),
+	.driver		= {
+		.name	= "nuc900-wdt",
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init nuc900_wdt_init(void)
+{
+	return platform_driver_register(&nuc900wdt_driver);
+}
+
+static void __exit nuc900_wdt_exit(void)
+{
+	platform_driver_unregister(&nuc900wdt_driver);
+}
+
+module_init(nuc900_wdt_init);
+module_exit(nuc900_wdt_exit);
+
+MODULE_AUTHOR("Wan ZongShun <mcuos.com@gmail.com>");
+MODULE_DESCRIPTION("Watchdog driver for NUC900");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
+MODULE_ALIAS("platform:nuc900-wdt");