Date:	Wed,  6 Jun 2007 16:04:07 +0200
From:	Hans-Christian Egtvedt <hcegtvedt@...el.com>
To:	linux-kernel@...r.kernel.org
Cc:	Hans-Christian Egtvedt <hcegtvedt@...el.com>,
	Haavard Skinnemoen <hskinnemoen@...el.com>
Subject: [PATCH 1/1] Watchdog driver for AT32AP700X devices

This patch adds support for the built in watchdog in AT32AP700X devices.

Tested on AT32AP7000 and ATSTK1000.

Hardware documentation can be found in the AT32AP7000 datasheet.

Signed-off-by: Hans-Christian Egtvedt <hcegtvedt@...el.com>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@...el.com>
---
 drivers/char/watchdog/Kconfig          |   20 ++
 drivers/char/watchdog/Makefile         |    3 +
 drivers/char/watchdog/at32ap700x_wdt.c |  313 ++++++++++++++++++++++++++++++++
 3 files changed, 336 insertions(+), 0 deletions(-)

diff --git a/drivers/char/watchdog/Kconfig b/drivers/char/watchdog/Kconfig
index e812aa1..84d9847 100644
--- a/drivers/char/watchdog/Kconfig
+++ b/drivers/char/watchdog/Kconfig
@@ -183,6 +183,26 @@ config PNX4008_WATCHDOG
 
 	  Say N if you are unsure.
 
+# AVR32 Architecture
+
+config AT32AP700X_WDT
+	tristate "AT32AP700x watchdog"
+	depends on WATCHDOG && CPU_AT32AP7000
+	help
+	  Watchdog timer embedded into AT32AP700x devices. This will reboot
+	  your system when the timeout is reached.
+
+config AT32AP700X_WDT_TIMEOUT
+	int "Timeout value for AT32AP700x watchdog"
+	depends on AT32AP700X_WDT
+	default "2"
+	range 1 2
+	help
+	  Sets the timeout value for the watchdog in AT32AP700x devices.
+	  Limited by hardware to be 1 or 2 seconds.
+
+	  Set to 2 seconds by default.
+
 # X86 (i386 + ia64 + x86_64) Architecture
 
 config ACQUIRE_WDT
diff --git a/drivers/char/watchdog/Makefile b/drivers/char/watchdog/Makefile
index 2cd8ff8..8b2a530 100644
--- a/drivers/char/watchdog/Makefile
+++ b/drivers/char/watchdog/Makefile
@@ -35,6 +35,9 @@ obj-$(CONFIG_MPCORE_WATCHDOG) += mpcore_wdt.o
 obj-$(CONFIG_EP93XX_WATCHDOG) += ep93xx_wdt.o
 obj-$(CONFIG_PNX4008_WATCHDOG) += pnx4008_wdt.o
 
+# AVR32 Architecture
+obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
+
 # X86 (i386 + ia64 + x86_64) Architecture
 obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o
 obj-$(CONFIG_ADVANTECH_WDT) += advantechwdt.o
diff --git a/drivers/char/watchdog/at32ap700x_wdt.c b/drivers/char/watchdog/at32ap700x_wdt.c
new file mode 100644
index 0000000..2a01e08
--- /dev/null
+++ b/drivers/char/watchdog/at32ap700x_wdt.c
@@ -0,0 +1,313 @@
+/*
+ * Watchdog driver for Atmel AT32AP700X devices
+ *
+ * Copyright (C) 2005-2006 Atmel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+
+#include <asm/uaccess.h>
+#include <asm/io.h>
+
+#define TIMEOUT_MIN		1
+#define TIMEOUT_DEFAULT		CONFIG_AT32AP700X_WDT_TIMEOUT
+#define TIMEOUT_MAX		2
+
+/* Watchdog registers and write/read macro */
+#define WDT_CTRL		0x00
+#define WDT_CTRL_EN		   0
+#define WDT_CTRL_PSEL		   8
+#define WDT_CTRL_KEY		  24
+
+#define WDT_CLR			0x04
+
+#define WDT_BIT(name)		(1 << WDT_##name)
+#define WDT_BF(name,value)	((value) << WDT_##name)
+
+#define wdt_readl(dev,reg)				\
+	__raw_readl((dev)->regs + WDT_##reg)
+#define wdt_writel(dev,reg,value)			\
+	__raw_writel((value), (dev)->regs + WDT_##reg)
+
+struct wdt_at32ap700x {
+	void __iomem		*regs;
+	int			timeout;
+	int			users;
+	struct miscdevice	miscdev;
+};
+
+static struct wdt_at32ap700x *wdt;
+
+/*
+ * Disable the watchdog.
+ */
+static void inline at32_wdt_stop(void)
+{
+	unsigned long psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f);
+	wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55));
+	wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa));
+}
+
+/*
+ * Enable and reset the watchdog.
+ */
+static void inline at32_wdt_start(void)
+{
+	/* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */
+	unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe;
+
+	wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
+			| WDT_BF(CTRL_PSEL, psel)
+			| WDT_BF(CTRL_KEY, 0x55));
+	wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
+			| WDT_BF(CTRL_PSEL, psel)
+			| WDT_BF(CTRL_KEY, 0xaa));
+}
+
+/*
+ * Pat the watchdog timer.
+ */
+static void inline at32_wdt_pat(void)
+{
+	wdt_writel(wdt, CLR, 0x42);
+}
+
+/*
+ * Watchdog device is opened, and watchdog starts running.
+ */
+static int at32_wdt_open(struct inode *inode, struct file *file)
+{
+	if (test_and_set_bit(1, &wdt->users))
+		return -EBUSY;
+
+	at32_wdt_start();
+	return nonseekable_open(inode, file);
+}
+
+/*
+ * Close the watchdog device. If CONFIG_WATCHDOG_NOWAYOUT is _not_ defined then
+ * the watchdog is also disabled.
+ */
+static int at32_wdt_close(struct inode *inode, struct file *file)
+{
+#ifndef CONFIG_WATCHDOG_NOWAYOUT
+	at32_wdt_stop();
+#endif
+	clear_bit(1, &wdt->users);
+	return 0;
+}
+
+/*
+ * Change the watchdog time interval.
+ */
+static int at32_wdt_settimeout(int time)
+{
+	/*
+	 * All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is
+	 * 2 ^ 16 allowing up to 2 seconds timeout.
+	 */
+	if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX))
+		return -EINVAL;
+
+	/* Set new watchdog time. It will be used when at32_wdt_start() is called. */
+	wdt->timeout = time;
+	return 0;
+}
+
+static struct watchdog_info at32_wdt_info = {
+	.identity	= "at32ap700x watchdog",
+	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+};
+
+/*
+ * Handle commands from user-space.
+ */
+static int at32_wdt_ioctl(struct inode *inode, struct file *file,
+		unsigned int cmd, unsigned long arg)
+{
+	int ret = -ENOTTY;
+	int time;
+	void __user *argp = (void __user *)arg;
+	int __user *p = argp;
+
+	switch(cmd) {
+	case WDIOC_KEEPALIVE:
+		at32_wdt_pat();
+		ret = 0;
+		break;
+	case WDIOC_GETSUPPORT:
+		ret = copy_to_user(argp, &at32_wdt_info,
+				sizeof(at32_wdt_info)) ? -EFAULT : 0;
+		break;
+	case WDIOC_SETTIMEOUT:
+		ret = get_user(time, p);
+		if (ret)
+			break;
+		ret = at32_wdt_settimeout(time);
+		if (ret)
+			break;
+		/* Enable new time value */
+		at32_wdt_start();
+		/* fall through */
+	case WDIOC_GETTIMEOUT:
+		ret = put_user(wdt->timeout, p);
+		break;
+	case WDIOC_GETSTATUS: /* fall through */
+	case WDIOC_GETBOOTSTATUS:
+		ret = put_user(0, p);
+		break;
+	case WDIOC_SETOPTIONS:
+		ret = get_user(time, p);
+		if (ret)
+			break;
+		if (time & WDIOS_DISABLECARD)
+			at32_wdt_stop();
+		if (time & WDIOS_ENABLECARD)
+			at32_wdt_start();
+		ret = 0;
+		break;
+	}
+
+	return ret;
+}
+
+static ssize_t at32_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
+{
+	at32_wdt_pat();
+	return len;
+}
+
+static const struct file_operations at32_wdt_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.ioctl		= at32_wdt_ioctl,
+	.open		= at32_wdt_open,
+	.release	= at32_wdt_close,
+	.write		= at32_wdt_write,
+};
+
+static int __init at32_wdt_probe(struct platform_device *pdev)
+{
+	struct resource	*regs;
+	int ret;
+
+	if (wdt) {
+		dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n");
+		return -EBUSY;
+	}
+
+	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!regs) {
+		dev_dbg(&pdev->dev, "missing mmio resource\n");
+		return -ENXIO;
+	}
+
+	wdt = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL);
+	if (!wdt) {
+		dev_dbg(&pdev->dev, "no memory for wdt structure\n");
+		return -ENOMEM;
+	}
+
+	wdt->regs = ioremap(regs->start, regs->end - regs->start + 1);
+	wdt->users = 0;
+	wdt->miscdev.minor = WATCHDOG_MINOR;
+	wdt->miscdev.name = "watchdog";
+	wdt->miscdev.fops = &at32_wdt_fops;
+
+	if (at32_wdt_settimeout(TIMEOUT_DEFAULT)) {
+		at32_wdt_settimeout(TIMEOUT_MAX);
+		dev_dbg(&pdev->dev,
+			"default timeout invalid, set to %d sec.\n",
+			TIMEOUT_MAX);
+	}
+
+	ret = misc_register(&wdt->miscdev);
+	if (ret) {
+		dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
+		goto err_register;
+	}
+
+	platform_set_drvdata(pdev, wdt);
+	wdt->miscdev.parent = &pdev->dev;
+	dev_info(&pdev->dev, "AT32AP700X WDT at 0x%p\n", wdt->regs);
+
+	return 0;
+
+err_register:
+	kfree(wdt);
+	wdt = NULL;
+	return ret;
+}
+
+static int __exit at32_wdt_remove(struct platform_device *pdev)
+{
+	if (wdt && platform_get_drvdata(pdev) == wdt) {
+		misc_deregister(&wdt->miscdev);
+		kfree(wdt);
+		wdt = NULL;
+		platform_set_drvdata(pdev, NULL);
+	}
+
+	return 0;
+}
+
+static void at32_wdt_shutdown(struct platform_device *pdev)
+{
+	at32_wdt_stop();
+}
+
+#ifdef CONFIG_PM
+static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
+{
+	at32_wdt_stop();
+	return 0;
+}
+
+static int at32_wdt_resume(struct platform_device *pdev)
+{
+	if (wdt->users)
+		at32_wdt_start();
+	return 0;
+}
+#endif
+
+static struct platform_driver at32_wdt_driver = {
+	.remove		= __exit_p(at32_wdt_remove),
+#ifdef CONFIG_PM
+	.suspend	= at32_wdt_suspend,
+	.resume		= at32_wdt_resume,
+#endif
+	.driver		= {
+		.name	= "at32_wdt",
+		.owner	= THIS_MODULE,
+	},
+	.shutdown	= at32_wdt_shutdown,
+};
+
+static int __init at32_wdt_init(void)
+{
+	return platform_driver_probe(&at32_wdt_driver, at32_wdt_probe);
+}
+module_init(at32_wdt_init);
+
+static void __exit at32_wdt_exit(void)
+{
+	platform_driver_unregister(&at32_wdt_driver);
+}
+module_exit(at32_wdt_exit);
+
+MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@...el.com>");
+MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
-- 
1.4.4.2

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