[PATCH 2/3] Blackfin on-chip watchdog driver

[Bryan Wu <bryan.wu@analog.com>]

This patch implements the driver necessary use the Analog Devices
Blackfin processor's on-chip watchdog controller, supports
BF53[123]/BF53[467]/BF54[2489]/BF561.

Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
---
 MAINTAINERS                      |    8 +
 drivers/char/watchdog/Kconfig    |   13 +
 drivers/char/watchdog/Makefile   |    3 +
 drivers/char/watchdog/bfin_wdt.c |  490 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 514 insertions(+), 0 deletions(-)
 create mode 100644 drivers/char/watchdog/bfin_wdt.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 21a2265..9ff42bd 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -776,6 +776,14 @@ L:	uclinux-dist-devel@blackfin.uclinux.org (subscribers-only)
 W:	http://blackfin.uclinux.org
 S:	Supported
 
+BLACKFIN WATCHDOG DRIVER
+P:	Mike Frysinger
+M:	michael.frysinger@analog.com
+M:	vapier.adi@gmail.com
+L:	uclinux-dist-devel@blackfin.uclinux.org (subscribers-only)
+W:	http://blackfin.uclinux.org
+S:	Supported
+
 BAYCOM/HDLCDRV DRIVERS FOR AX.25
 P:	Thomas Sailer
 M:	t.sailer@alumni.ethz.ch
diff --git a/drivers/char/watchdog/Kconfig b/drivers/char/watchdog/Kconfig
index 53f5538..40f2ce1 100644
--- a/drivers/char/watchdog/Kconfig
+++ b/drivers/char/watchdog/Kconfig
@@ -616,6 +616,19 @@ config SH_WDT_MMAP
 	  If you say Y here, user applications will be able to mmap the
 	  WDT/CPG registers.
 
+# Blackfin Architecture
+
+config BFIN_WDT
+	tristate "Blackfin On-Chip Watchdog Timer"
+	depends on WATCHDOG && BLACKFIN
+	---help---
+	  If you say yes here you will get support for the Blackfin On-Chip
+	  Watchdog Timer. If you have one of these processors and wish to
+	  have watchdog support enabled, say Y, otherwise say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called bfin_wdt.
+
 # SPARC64 Architecture
 
 config WATCHDOG_CP1XXX
diff --git a/drivers/char/watchdog/Makefile b/drivers/char/watchdog/Makefile
index d90f649..86aae7e 100644
--- a/drivers/char/watchdog/Makefile
+++ b/drivers/char/watchdog/Makefile
@@ -81,6 +81,9 @@ obj-$(CONFIG_WDT_RM9K_GPI) += rm9k_wdt.o
 # SUPERH Architecture
 obj-$(CONFIG_SH_WDT) += shwdt.o
 
+# Blackfin Architecture
+obj-$(CONFIG_BFIN_WDT) += bfin_wdt.o
+
 # SPARC64 Architecture
 
 # Architecture Independant
diff --git a/drivers/char/watchdog/bfin_wdt.c b/drivers/char/watchdog/bfin_wdt.c
new file mode 100644
index 0000000..309d279
--- /dev/null
+++ b/drivers/char/watchdog/bfin_wdt.c
@@ -0,0 +1,490 @@
+/*
+ * Blackfin On-Chip Watchdog Driver
+ *  Supports BF53[123]/BF53[467]/BF54[2489]/BF561
+ *
+ * Originally based on softdog.c
+ * Copyright 2006-2007 Analog Devices Inc.
+ * Copyright 2006-2007 Michele d'Amico
+ * Copyright 1996 Alan Cox <alan@redhat.com>
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/timer.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/fs.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <asm/blackfin.h>
+#include <asm/uaccess.h>
+
+#define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
+#define stampit() stamp("here i am")
+
+#define WATCHDOG_NAME "bfin-wdt"
+#define PFX WATCHDOG_NAME ": "
+
+/* The BF561 has two watchdogs (one per core), but since Linux
+ * only runs on core A, we'll just work with that one.
+ */
+#ifdef BF561_FAMILY
+# define bfin_read_WDOG_CTL()    bfin_read_WDOGA_CTL()
+# define bfin_read_WDOG_CNT()    bfin_read_WDOGA_CNT()
+# define bfin_read_WDOG_STAT()   bfin_read_WDOGA_STAT()
+# define bfin_write_WDOG_CTL(x)  bfin_write_WDOGA_CTL(x)
+# define bfin_write_WDOG_CNT(x)  bfin_write_WDOGA_CNT(x)
+# define bfin_write_WDOG_STAT(x) bfin_write_WDOGA_STAT(x)
+#endif
+
+/* Bit in SWRST that indicates boot caused by watchdog */
+#define SWRST_RESET_WDOG 0x4000
+
+/* Bit in WDOG_CTL that indicates watchdog has expired (WDR0) */
+#define WDOG_EXPIRED 0x8000
+
+/* Masks for WDEV field in WDOG_CTL register */
+#define ICTL_RESET   0x0
+#define ICTL_NMI     0x2
+#define ICTL_GPI     0x4
+#define ICTL_NONE    0x6
+#define ICTL_MASK    0x6
+
+/* Masks for WDEN field in WDOG_CTL register */
+#define WDEN_MASK    0x0FF0
+#define WDEN_ENABLE  0x0000
+#define WDEN_DISABLE 0x0AD0
+
+/* some defaults */
+#define WATCHDOG_TIMEOUT 20
+
+static unsigned int timeout = WATCHDOG_TIMEOUT;
+static int nowayout = WATCHDOG_NOWAYOUT;
+static struct watchdog_info bfin_wdt_info;
+static unsigned long open_check;
+static char expect_close;
+static spinlock_t bfin_wdt_spinlock = SPIN_LOCK_UNLOCKED;
+
+/**
+ *	bfin_wdt_keepalive - Keep the Userspace Watchdog Alive
+ *
+ * 	The Userspace watchdog got a KeepAlive: schedule the next timeout.
+ */
+static int bfin_wdt_keepalive(void)
+{
+	stampit();
+	bfin_write_WDOG_STAT(0);
+	return 0;
+}
+
+/**
+ *	bfin_wdt_stop - Stop the Watchdog
+ *
+ *	Stops the on-chip watchdog.
+ */
+static int bfin_wdt_stop(void)
+{
+	stampit();
+	bfin_write_WDOG_CTL(WDEN_DISABLE);
+	return 0;
+}
+
+/**
+ *	bfin_wdt_start - Start the Watchdog
+ *
+ *	Starts the on-chip watchdog.  Automatically loads WDOG_CNT
+ *	into WDOG_STAT for us.
+ */
+static int bfin_wdt_start(void)
+{
+	stampit();
+	bfin_write_WDOG_CTL(WDEN_ENABLE | ICTL_RESET);
+	return 0;
+}
+
+/**
+ *	bfin_wdt_running - Check Watchdog status
+ *
+ *	See if the watchdog is running.
+ */
+static int bfin_wdt_running(void)
+{
+	stampit();
+	return ((bfin_read_WDOG_CTL() & WDEN_MASK) != WDEN_DISABLE);
+}
+
+/**
+ *	bfin_wdt_set_timeout - Set the Userspace Watchdog timeout
+ *	@t: new timeout value (in seconds)
+ *
+ *	Translate the specified timeout in seconds into System Clock
+ *	terms which is what the on-chip Watchdog requires.
+ */
+static int bfin_wdt_set_timeout(unsigned long t)
+{
+	u32 cnt;
+	unsigned long flags;
+
+	stampit();
+
+	cnt = t * get_sclk();
+	if (cnt < get_sclk()) {
+		printk(KERN_WARNING PFX "timeout value is too large\n");
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&bfin_wdt_spinlock, flags);
+	{
+		int run = bfin_wdt_running();
+		bfin_wdt_stop();
+		bfin_write_WDOG_CNT(cnt);
+		if (run) bfin_wdt_start();
+	}
+	spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
+
+	timeout = t;
+
+	return 0;
+}
+
+/**
+ *	bfin_wdt_open - Open the Device
+ *	@inode: inode of device
+ *	@file: file handle of device
+ *
+ *	Watchdog device is opened and started.
+ */
+static int bfin_wdt_open(struct inode *inode, struct file *file)
+{
+	stampit();
+
+	if (test_and_set_bit(0, &open_check))
+		return -EBUSY;
+
+	if (nowayout)
+		__module_get(THIS_MODULE);
+
+	bfin_wdt_keepalive();
+	bfin_wdt_start();
+
+	return nonseekable_open(inode, file);
+}
+
+/**
+ *	bfin_wdt_close - Close the Device
+ *	@inode: inode of device
+ *	@file: file handle of device
+ *
+ *	Watchdog device is closed and stopped.
+ */
+static int bfin_wdt_release(struct inode *inode, struct file *file)
+{
+	stampit();
+
+	if (expect_close == 42) {
+		bfin_wdt_stop();
+	} else {
+		printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
+		bfin_wdt_keepalive();
+	}
+
+	expect_close = 0;
+	clear_bit(0, &open_check);
+
+	return 0;
+}
+
+/**
+ *	bfin_wdt_write - Write to Device
+ *	@file: file handle of device
+ *	@buf: buffer to write
+ *	@count: length of buffer
+ *	@ppos: offset
+ *
+ *	Pings the watchdog on write.
+ */
+static ssize_t bfin_wdt_write(struct file *file, const char __user *data,
+                              size_t len, loff_t *ppos)
+{
+	stampit();
+
+	if (len) {
+		if (!nowayout) {
+			size_t i;
+
+			/* In case it was set long ago */
+			expect_close = 0;
+
+			for (i = 0; i != len; i++) {
+				char c;
+				if (get_user(c, data + i))
+					return -EFAULT;
+				if (c == 'V')
+					expect_close = 42;
+			}
+		}
+		bfin_wdt_keepalive();
+	}
+
+	return len;
+}
+
+/**
+ *	bfin_wdt_ioctl - Query Device
+ *	@inode: inode of device
+ *	@file: file handle of device
+ *	@cmd: watchdog command
+ *	@arg: argument
+ *
+ *	Query basic information from the device or ping it, as outlined by the
+ *	watchdog API.
+ */
+static int bfin_wdt_ioctl(struct inode *inode, struct file *file,
+                          unsigned int cmd, unsigned long arg)
+{
+	void __user *argp = (void __user *)arg;
+	int __user *p = argp;
+
+	stampit();
+
+	switch (cmd) {
+		default:
+			return -ENOTTY;
+
+		case WDIOC_GETSUPPORT:
+			if (copy_to_user(argp, &bfin_wdt_info, sizeof(bfin_wdt_info)))
+				return -EFAULT;
+			else
+				return 0;
+
+		case WDIOC_GETSTATUS:
+		case WDIOC_GETBOOTSTATUS:
+			return put_user(!!(_bfin_swrst & SWRST_RESET_WDOG), p);
+
+		case WDIOC_KEEPALIVE:
+			bfin_wdt_keepalive();
+			return 0;
+
+		case WDIOC_SETTIMEOUT: {
+			int new_timeout;
+
+			if (get_user(new_timeout, p))
+				return -EFAULT;
+
+			if (bfin_wdt_set_timeout(new_timeout))
+				return -EINVAL;
+		}
+			/* Fall */
+		case WDIOC_GETTIMEOUT:
+			return put_user(timeout, p);
+
+		case WDIOC_SETOPTIONS: {
+			unsigned long flags;
+			int options, ret = -EINVAL;
+
+			if (get_user(options, p))
+				return -EFAULT;
+
+			spin_lock_irqsave(&bfin_wdt_spinlock, flags);
+
+			if (options & WDIOS_DISABLECARD) {
+				bfin_wdt_stop();
+				ret = 0;
+			}
+
+			if (options & WDIOS_ENABLECARD) {
+				bfin_wdt_start();
+				ret = 0;
+			}
+
+			spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
+
+			return ret;
+		}
+	}
+}
+
+/**
+ *	bfin_wdt_notify_sys - Notifier Handler
+ *	@this: notifier block
+ *	@code: notifier event
+ *	@unused: unused
+ *
+ *	Handles specific events, such as turning off the watchdog during a
+ *	shutdown event.
+ */
+static int bfin_wdt_notify_sys(struct notifier_block *this, unsigned long code,
+                               void *unused)
+{
+	stampit();
+
+	if (code == SYS_DOWN || code == SYS_HALT)
+		bfin_wdt_stop();
+
+	return NOTIFY_DONE;
+}
+
+#ifdef CONFIG_PM
+static int state_before_suspend;
+
+/**
+ *	bfin_wdt_suspend - suspend the watchdog
+ *	@pdev: device being suspended
+ *	@state: requested suspend state
+ *
+ *	Remember if the watchdog was running and stop it.
+ *	TODO: is this even right?  Doesn't seem to be any
+ *	      standard in the watchdog world ...
+ */
+static int bfin_wdt_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	stampit();
+
+	state_before_suspend = bfin_wdt_running();
+	bfin_wdt_stop();
+
+	return 0;
+}
+
+/**
+ *	bfin_wdt_resume - resume the watchdog
+ *	@pdev: device being resumed
+ *
+ *	If the watchdog was running, turn it back on.
+ */
+static int bfin_wdt_resume(struct platform_device *pdev)
+{
+	stampit();
+
+	if (state_before_suspend) {
+		bfin_wdt_set_timeout(timeout);
+		bfin_wdt_start();
+	}
+
+	return 0;
+}
+#else
+# define bfin_wdt_suspend NULL
+# define bfin_wdt_resume NULL
+#endif
+
+static struct platform_device bfin_wdt_device = {
+	.name          = WATCHDOG_NAME,
+	.id            = -1,
+};
+
+static struct platform_driver bfin_wdt_driver = {
+	.driver    = {
+		.name  = WATCHDOG_NAME,
+		.owner = THIS_MODULE,
+	},
+	.suspend   = bfin_wdt_suspend,
+	.resume    = bfin_wdt_resume,
+};
+
+static struct file_operations bfin_wdt_fops = {
+	.owner    = THIS_MODULE,
+	.llseek   = no_llseek,
+	.write    = bfin_wdt_write,
+	.ioctl    = bfin_wdt_ioctl,
+	.open     = bfin_wdt_open,
+	.release  = bfin_wdt_release,
+};
+
+static struct miscdevice bfin_wdt_miscdev = {
+	.minor    = WATCHDOG_MINOR,
+	.name     = "watchdog",
+	.fops     = &bfin_wdt_fops,
+};
+
+static struct watchdog_info bfin_wdt_info = {
+	.identity = "Blackfin Watchdog",
+	.options  = WDIOF_SETTIMEOUT |
+	            WDIOF_KEEPALIVEPING |
+	            WDIOF_MAGICCLOSE,
+};
+
+static struct notifier_block bfin_wdt_notifier = {
+	.notifier_call = bfin_wdt_notify_sys,
+};
+
+/**
+ *	bfin_wdt_init - Initialize module
+ *
+ *	Registers the device and notifier handler. Actual device
+ *	initialization is handled by bfin_wdt_open().
+ */
+static int __init bfin_wdt_init(void)
+{
+	int ret;
+
+	stampit();
+
+	/* Check that the timeout value is within range */
+	if (bfin_wdt_set_timeout(timeout))
+		return -EINVAL;
+
+	/* Since this is an on-chip device and needs no board-specific
+	 * resources, we'll handle all the platform device stuff here.
+	 */
+	ret = platform_device_register(&bfin_wdt_device);
+	if (ret)
+		return ret;
+
+	ret = platform_driver_probe(&bfin_wdt_driver, NULL);
+	if (ret)
+		return ret;
+
+	ret = register_reboot_notifier(&bfin_wdt_notifier);
+	if (ret) {
+		printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", ret);
+		return ret;
+	}
+
+	ret = misc_register(&bfin_wdt_miscdev);
+	if (ret) {
+		printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
+		       WATCHDOG_MINOR, ret);
+		unregister_reboot_notifier(&bfin_wdt_notifier);
+		return ret;
+	}
+
+	printk(KERN_INFO PFX "initialized: timeout=%d sec (nowayout=%d)\n",
+	       timeout, nowayout);
+
+	return 0;
+}
+
+/**
+ *	bfin_wdt_exit - Deinitialize module
+ *
+ *	Unregisters the device and notifier handler. Actual device
+ *	deinitialization is handled by bfin_wdt_close().
+ */
+static void __exit bfin_wdt_exit(void)
+{
+	misc_deregister(&bfin_wdt_miscdev);
+	unregister_reboot_notifier(&bfin_wdt_notifier);
+}
+
+module_init(bfin_wdt_init);
+module_exit(bfin_wdt_exit);
+
+MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>");
+MODULE_DESCRIPTION("Blackfin Watchdog Device Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
+
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
+
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
-- 
1.5.2