watchdog: Add Xilinx watchdog timer driver

Watchdog timer device driver for Xilinx xps_timebase_wdt compatible ip cores.
It takes watchdog timer configuration from device tree and it needs that its
parent has defined the property "clock-frecuency".
It is compatible with watchdog timer kernel API, so user apps like watchdogd
may talk with it.

Signed-off-by: Alejandro Cabrera <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/Kconfig

···
 	  To compile this driver as a module, choose M here: the
 	  module will be called m54xx_wdt.
 
+# MicroBlaze Architecture
+
+config XILINX_WATCHDOG
+	tristate "Xilinx Watchdog timer"
+	depends on MICROBLAZE
+	---help---
+	  Watchdog driver for the xps_timebase_wdt ip core.
+
+	  IMPORTANT: The xps_timebase_wdt parent must have the property
+	  "clock-frequency" at device tree.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called of_xilinx_wdt.
+
 # MIPS Architecture
 
 config ATH79_WDT

drivers/watchdog/Makefile

···
 # M68K Architecture
 obj-$(CONFIG_M54xx_WATCHDOG) += m54xx_wdt.o
 
+# MicroBlaze Architecture
+obj-$(CONFIG_XILINX_WATCHDOG) += of_xilinx_wdt.o
+
 # MIPS Architecture
 obj-$(CONFIG_ATH79_WDT) += ath79_wdt.o
 obj-$(CONFIG_BCM47XX_WDT) += bcm47xx_wdt.o

drivers/watchdog/of_xilinx_wdt.c

···
+/*
+*   of_xilinx_wdt.c  1.01  A Watchdog Device Driver for Xilinx xps_timebase_wdt
+*
+*   (C) Copyright 2011 (Alejandro Cabrera <[e-mail]>)
+*
+*       -----------------------
+*
+*   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; either version
+*   2 of the License, or (at your option) any later version.
+*
+*       -----------------------
+*	30-May-2011 Alejandro Cabrera <[e-mail]>
+*		- If "xlnx,wdt-enable-once" wasn't found on device tree the
+*		  module will use CONFIG_WATCHDOG_NOWAYOUT
+*		- If the device tree parameters ("clock-frequency" and
+*		  "xlnx,wdt-interval") wasn't found the driver won't
+*		  know the wdt reset interval
+*/
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/watchdog.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_address.h>
+
+/* Register offsets for the Wdt device */
+#define XWT_TWCSR0_OFFSET   0x0 /* Control/Status Register0 */
+#define XWT_TWCSR1_OFFSET   0x4 /* Control/Status Register1 */
+#define XWT_TBR_OFFSET      0x8 /* Timebase Register Offset */
+
+/* Control/Status Register Masks  */
+#define XWT_CSR0_WRS_MASK   0x00000008 /* Reset status */
+#define XWT_CSR0_WDS_MASK   0x00000004 /* Timer state  */
+#define XWT_CSR0_EWDT1_MASK 0x00000002 /* Enable bit 1 */
+
+/* Control/Status Register 0/1 bits  */
+#define XWT_CSRX_EWDT2_MASK 0x00000001 /* Enable bit 2 */
+
+/* SelfTest constants */
+#define XWT_MAX_SELFTEST_LOOP_COUNT 0x00010000
+#define XWT_TIMER_FAILED            0xFFFFFFFF
+
+#define WATCHDOG_NAME     "Xilinx Watchdog"
+#define PFX WATCHDOG_NAME ": "
+
+struct xwdt_device {
+	struct resource  res;
+	void __iomem *base;
+	u32 nowayout;
+	u32 wdt_interval;
+	u32 boot_status;
+};
+
+static struct xwdt_device xdev;
+
+static  u32 timeout;
+static  u32 control_status_reg;
+static  u8  expect_close;
+static  u8  no_timeout;
+static unsigned long driver_open;
+
+static  DEFINE_SPINLOCK(spinlock);
+
+static void xwdt_start(void)
+{
+	spin_lock(&spinlock);
+
+	/* Clean previous status and enable the watchdog timer */
+	control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
+	control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
+
+	iowrite32((control_status_reg | XWT_CSR0_EWDT1_MASK),
+				xdev.base + XWT_TWCSR0_OFFSET);
+
+	iowrite32(XWT_CSRX_EWDT2_MASK, xdev.base + XWT_TWCSR1_OFFSET);
+
+	spin_unlock(&spinlock);
+}
+
+static void xwdt_stop(void)
+{
+	spin_lock(&spinlock);
+
+	control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
+
+	iowrite32((control_status_reg & ~XWT_CSR0_EWDT1_MASK),
+				xdev.base + XWT_TWCSR0_OFFSET);
+
+	iowrite32(0, xdev.base + XWT_TWCSR1_OFFSET);
+
+	spin_unlock(&spinlock);
+	printk(KERN_INFO PFX "Stopped!\n");
+}
+
+static void xwdt_keepalive(void)
+{
+	spin_lock(&spinlock);
+
+	control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
+	control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
+	iowrite32(control_status_reg, xdev.base + XWT_TWCSR0_OFFSET);
+
+	spin_unlock(&spinlock);
+}
+
+static void xwdt_get_status(int *status)
+{
+	int new_status;
+
+	spin_lock(&spinlock);
+
+	control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
+	new_status = ((control_status_reg &
+			(XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK)) != 0);
+	spin_unlock(&spinlock);
+
+	*status = 0;
+	if (new_status & 1)
+		*status |= WDIOF_CARDRESET;
+}
+
+static u32 xwdt_selftest(void)
+{
+	int i;
+	u32 timer_value1;
+	u32 timer_value2;
+
+	spin_lock(&spinlock);
+
+	timer_value1 = ioread32(xdev.base + XWT_TBR_OFFSET);
+	timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET);
+
+	for (i = 0;
+		((i <= XWT_MAX_SELFTEST_LOOP_COUNT) &&
+			(timer_value2 == timer_value1)); i++) {
+		timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET);
+	}
+
+	spin_unlock(&spinlock);
+
+	if (timer_value2 != timer_value1)
+		return ~XWT_TIMER_FAILED;
+	else
+		return XWT_TIMER_FAILED;
+}
+
+static int xwdt_open(struct inode *inode, struct file *file)
+{
+	/* Only one process can handle the wdt at a time */
+	if (test_and_set_bit(0, &driver_open))
+		return -EBUSY;
+
+	/* Make sure that the module are always loaded...*/
+	if (xdev.nowayout)
+		__module_get(THIS_MODULE);
+
+	xwdt_start();
+	printk(KERN_INFO PFX "Started...\n");
+
+	return nonseekable_open(inode, file);
+}
+
+static int xwdt_release(struct inode *inode, struct file *file)
+{
+	if (expect_close == 42) {
+		xwdt_stop();
+	} else {
+		printk(KERN_CRIT PFX
+			"Unexpected close, not stopping watchdog!\n");
+		xwdt_keepalive();
+	}
+
+	clear_bit(0, &driver_open);
+	expect_close = 0;
+	return 0;
+}
+
+/*
+ *      xwdt_write:
+ *      @file: file handle to the watchdog
+ *      @buf: buffer to write (unused as data does not matter here
+ *      @count: count of bytes
+ *      @ppos: pointer to the position to write. No seeks allowed
+ *
+ *      A write to a watchdog device is defined as a keepalive signal. Any
+ *      write of data will do, as we don't define content meaning.
+ */
+static ssize_t xwdt_write(struct file *file, const char __user *buf,
+						size_t len, loff_t *ppos)
+{
+	if (len) {
+		if (!xdev.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, buf + i))
+					return -EFAULT;
+				if (c == 'V')
+					expect_close = 42;
+			}
+		}
+		xwdt_keepalive();
+	}
+	return len;
+}
+
+static const struct watchdog_info ident = {
+	.options =  WDIOF_MAGICCLOSE |
+		    WDIOF_KEEPALIVEPING,
+	.firmware_version =	1,
+	.identity =	WATCHDOG_NAME,
+};
+
+/*
+ *      xwdt_ioctl:
+ *      @file: file handle to the device
+ *      @cmd: watchdog command
+ *      @arg: argument pointer
+ *
+ *      The watchdog API defines a common set of functions for all watchdogs
+ *      according to their available features.
+ */
+static long xwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	int status;
+
+	union {
+		struct watchdog_info __user *ident;
+		int __user *i;
+	} uarg;
+
+	uarg.i = (int __user *)arg;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		return copy_to_user(uarg.ident, &ident,
+					sizeof(ident)) ? -EFAULT : 0;
+
+	case WDIOC_GETBOOTSTATUS:
+		return put_user(xdev.boot_status, uarg.i);
+
+	case WDIOC_GETSTATUS:
+		xwdt_get_status(&status);
+		return put_user(status, uarg.i);
+
+	case WDIOC_KEEPALIVE:
+		xwdt_keepalive();
+		return 0;
+
+	case WDIOC_GETTIMEOUT:
+		if (no_timeout)
+			return -ENOTTY;
+		else
+			return put_user(timeout, uarg.i);
+
+	default:
+		return -ENOTTY;
+	}
+}
+
+static const struct file_operations xwdt_fops = {
+	.owner      = THIS_MODULE,
+	.llseek     = no_llseek,
+	.write      = xwdt_write,
+	.open       = xwdt_open,
+	.release    = xwdt_release,
+	.unlocked_ioctl = xwdt_ioctl,
+};
+
+static struct miscdevice xwdt_miscdev = {
+	.minor      = WATCHDOG_MINOR,
+	.name       = "watchdog",
+	.fops       = &xwdt_fops,
+};
+
+static int __devinit xwdt_probe(struct platform_device *pdev)
+{
+	int rc;
+	u32 *tmptr;
+	u32 *pfreq;
+
+	no_timeout = 0;
+
+	pfreq = (u32 *)of_get_property(pdev->dev.of_node->parent,
+					"clock-frequency", NULL);
+
+	if (pfreq == NULL) {
+		printk(KERN_WARNING PFX
+			"The watchdog clock frequency cannot be obtained!\n");
+		no_timeout = 1;
+	}
+
+	rc = of_address_to_resource(pdev->dev.of_node, 0, &xdev.res);
+	if (rc) {
+		printk(KERN_WARNING PFX "invalid address!\n");
+		return rc;
+	}
+
+	tmptr = (u32 *)of_get_property(pdev->dev.of_node,
+					"xlnx,wdt-interval", NULL);
+	if (tmptr == NULL) {
+		printk(KERN_WARNING PFX "Parameter \"xlnx,wdt-interval\""
+					" not found in device tree!\n");
+		no_timeout = 1;
+	} else {
+		xdev.wdt_interval = *tmptr;
+	}
+
+	tmptr = (u32 *)of_get_property(pdev->dev.of_node,
+					"xlnx,wdt-enable-once", NULL);
+	if (tmptr == NULL) {
+		printk(KERN_WARNING PFX "Parameter \"xlnx,wdt-enable-once\""
+					" not found in device tree!\n");
+		xdev.nowayout = WATCHDOG_NOWAYOUT;
+	}
+
+/*
+ *  Twice of the 2^wdt_interval / freq  because the first wdt overflow is
+ *  ignored (interrupt), reset is only generated at second wdt overflow
+ */
+	if (!no_timeout)
+		timeout = 2 * ((1<<xdev.wdt_interval) / *pfreq);
+
+	if (!request_mem_region(xdev.res.start,
+			xdev.res.end - xdev.res.start + 1, WATCHDOG_NAME)) {
+		rc = -ENXIO;
+		printk(KERN_ERR PFX "memory request failure!\n");
+		goto err_out;
+	}
+
+	xdev.base = ioremap(xdev.res.start, xdev.res.end - xdev.res.start + 1);
+	if (xdev.base == NULL) {
+		rc = -ENOMEM;
+		printk(KERN_ERR PFX "ioremap failure!\n");
+		goto release_mem;
+	}
+
+	rc = xwdt_selftest();
+	if (rc == XWT_TIMER_FAILED) {
+		printk(KERN_ERR PFX "SelfTest routine error!\n");
+		goto unmap_io;
+	}
+
+	xwdt_get_status(&xdev.boot_status);
+
+	rc = misc_register(&xwdt_miscdev);
+	if (rc) {
+		printk(KERN_ERR PFX
+			"cannot register miscdev on minor=%d (err=%d)\n",
+						xwdt_miscdev.minor, rc);
+		goto unmap_io;
+	}
+
+	if (no_timeout)
+		printk(KERN_INFO PFX
+			"driver loaded (timeout=? sec, nowayout=%d)\n",
+						    xdev.nowayout);
+	else
+		printk(KERN_INFO PFX
+			"driver loaded (timeout=%d sec, nowayout=%d)\n",
+					timeout, xdev.nowayout);
+
+	expect_close = 0;
+	clear_bit(0, &driver_open);
+
+	return 0;
+
+unmap_io:
+	iounmap(xdev.base);
+release_mem:
+	release_mem_region(xdev.res.start, resource_size(&xdev.res));
+err_out:
+	return rc;
+}
+
+static int __devexit xwdt_remove(struct platform_device *dev)
+{
+	misc_deregister(&xwdt_miscdev);
+	iounmap(xdev.base);
+	release_mem_region(xdev.res.start, resource_size(&xdev.res));
+
+	return 0;
+}
+
+/* Match table for of_platform binding */
+static struct of_device_id __devinitdata xwdt_of_match[] = {
+	{ .compatible = "xlnx,xps-timebase-wdt-1.01.a", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, xwdt_of_match);
+
+static struct platform_driver xwdt_driver = {
+	.probe       = xwdt_probe,
+	.remove      = __devexit_p(xwdt_remove),
+	.driver = {
+		.owner = THIS_MODULE,
+		.name  = WATCHDOG_NAME,
+		.of_match_table = xwdt_of_match,
+	},
+};
+
+static int __init xwdt_init(void)
+{
+	return platform_driver_register(&xwdt_driver);
+}
+
+static void __exit xwdt_exit(void)
+{
+	platform_driver_unregister(&xwdt_driver);
+}
+
+module_init(xwdt_init);
+module_exit(xwdt_exit);
+
+MODULE_AUTHOR("Alejandro Cabrera <[e-mail]>");
+MODULE_DESCRIPTION("Xilinx Watchdog driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);