2 * Watchdog Device Driver for Xilinx axi/xps_timebase_wdt
4 * (C) Copyright 2011 (Alejandro Cabrera <aldaya@gmail.com>)
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14 #include <linux/module.h>
15 #include <linux/types.h>
16 #include <linux/kernel.h>
18 #include <linux/miscdevice.h>
19 #include <linux/init.h>
20 #include <linux/ioport.h>
21 #include <linux/watchdog.h>
23 #include <linux/uaccess.h>
25 #include <linux/of_device.h>
26 #include <linux/of_address.h>
28 /* Register offsets for the Wdt device */
29 #define XWT_TWCSR0_OFFSET 0x0 /* Control/Status Register0 */
30 #define XWT_TWCSR1_OFFSET 0x4 /* Control/Status Register1 */
31 #define XWT_TBR_OFFSET 0x8 /* Timebase Register Offset */
33 /* Control/Status Register Masks */
34 #define XWT_CSR0_WRS_MASK 0x00000008 /* Reset status */
35 #define XWT_CSR0_WDS_MASK 0x00000004 /* Timer state */
36 #define XWT_CSR0_EWDT1_MASK 0x00000002 /* Enable bit 1 */
38 /* Control/Status Register 0/1 bits */
39 #define XWT_CSRX_EWDT2_MASK 0x00000001 /* Enable bit 2 */
41 /* SelfTest constants */
42 #define XWT_MAX_SELFTEST_LOOP_COUNT 0x00010000
43 #define XWT_TIMER_FAILED 0xFFFFFFFF
45 #define WATCHDOG_NAME "Xilinx Watchdog"
46 #define PFX WATCHDOG_NAME ": "
56 static struct xwdt_device xdev;
59 static u32 control_status_reg;
60 static u8 expect_close;
62 static unsigned long driver_open;
64 static DEFINE_SPINLOCK(spinlock);
66 static void xwdt_start(void)
70 /* Clean previous status and enable the watchdog timer */
71 control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
72 control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
74 iowrite32((control_status_reg | XWT_CSR0_EWDT1_MASK),
75 xdev.base + XWT_TWCSR0_OFFSET);
77 iowrite32(XWT_CSRX_EWDT2_MASK, xdev.base + XWT_TWCSR1_OFFSET);
79 spin_unlock(&spinlock);
82 static void xwdt_stop(void)
86 control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
88 iowrite32((control_status_reg & ~XWT_CSR0_EWDT1_MASK),
89 xdev.base + XWT_TWCSR0_OFFSET);
91 iowrite32(0, xdev.base + XWT_TWCSR1_OFFSET);
93 spin_unlock(&spinlock);
94 pr_info("Stopped!\n");
97 static void xwdt_keepalive(void)
101 control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
102 control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
103 iowrite32(control_status_reg, xdev.base + XWT_TWCSR0_OFFSET);
105 spin_unlock(&spinlock);
108 static void xwdt_get_status(int *status)
112 spin_lock(&spinlock);
114 control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
115 new_status = ((control_status_reg &
116 (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK)) != 0);
117 spin_unlock(&spinlock);
121 *status |= WDIOF_CARDRESET;
124 static u32 xwdt_selftest(void)
130 spin_lock(&spinlock);
132 timer_value1 = ioread32(xdev.base + XWT_TBR_OFFSET);
133 timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET);
136 ((i <= XWT_MAX_SELFTEST_LOOP_COUNT) &&
137 (timer_value2 == timer_value1)); i++) {
138 timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET);
141 spin_unlock(&spinlock);
143 if (timer_value2 != timer_value1)
144 return ~XWT_TIMER_FAILED;
146 return XWT_TIMER_FAILED;
149 static int xwdt_open(struct inode *inode, struct file *file)
151 /* Only one process can handle the wdt at a time */
152 if (test_and_set_bit(0, &driver_open))
155 /* Make sure that the module are always loaded...*/
157 __module_get(THIS_MODULE);
160 pr_info("Started...\n");
162 return nonseekable_open(inode, file);
165 static int xwdt_release(struct inode *inode, struct file *file)
167 if (expect_close == 42) {
170 pr_crit("Unexpected close, not stopping watchdog!\n");
174 clear_bit(0, &driver_open);
181 * @file: file handle to the watchdog
182 * @buf: buffer to write (unused as data does not matter here
183 * @count: count of bytes
184 * @ppos: pointer to the position to write. No seeks allowed
186 * A write to a watchdog device is defined as a keepalive signal. Any
187 * write of data will do, as we don't define content meaning.
189 static ssize_t xwdt_write(struct file *file, const char __user *buf,
190 size_t len, loff_t *ppos)
193 if (!xdev.nowayout) {
196 /* In case it was set long ago */
199 for (i = 0; i != len; i++) {
202 if (get_user(c, buf + i))
213 static const struct watchdog_info ident = {
214 .options = WDIOF_MAGICCLOSE |
216 .firmware_version = 1,
217 .identity = WATCHDOG_NAME,
222 * @file: file handle to the device
223 * @cmd: watchdog command
224 * @arg: argument pointer
226 * The watchdog API defines a common set of functions for all watchdogs
227 * according to their available features.
229 static long xwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
234 struct watchdog_info __user *ident;
238 uarg.i = (int __user *)arg;
241 case WDIOC_GETSUPPORT:
242 return copy_to_user(uarg.ident, &ident,
243 sizeof(ident)) ? -EFAULT : 0;
245 case WDIOC_GETBOOTSTATUS:
246 return put_user(xdev.boot_status, uarg.i);
248 case WDIOC_GETSTATUS:
249 xwdt_get_status(&status);
250 return put_user(status, uarg.i);
252 case WDIOC_KEEPALIVE:
256 case WDIOC_GETTIMEOUT:
260 return put_user(timeout, uarg.i);
267 static const struct file_operations xwdt_fops = {
268 .owner = THIS_MODULE,
272 .release = xwdt_release,
273 .unlocked_ioctl = xwdt_ioctl,
276 static struct miscdevice xwdt_miscdev = {
277 .minor = WATCHDOG_MINOR,
282 static int xwdt_probe(struct platform_device *pdev)
290 pfreq = (u32 *)of_get_property(pdev->dev.of_node,
291 "clock-frequency", NULL);
294 pr_warn("The watchdog clock frequency cannot be obtained!\n");
298 rc = of_address_to_resource(pdev->dev.of_node, 0, &xdev.res);
300 pr_warn("invalid address!\n");
304 tmptr = (u32 *)of_get_property(pdev->dev.of_node,
305 "xlnx,wdt-interval", NULL);
307 pr_warn("Parameter \"xlnx,wdt-interval\" not found in device tree!\n");
310 xdev.wdt_interval = *tmptr;
313 tmptr = (u32 *)of_get_property(pdev->dev.of_node,
314 "xlnx,wdt-enable-once", NULL);
316 pr_warn("Parameter \"xlnx,wdt-enable-once\" not found in device tree!\n");
317 xdev.nowayout = WATCHDOG_NOWAYOUT;
321 * Twice of the 2^wdt_interval / freq because the first wdt overflow is
322 * ignored (interrupt), reset is only generated at second wdt overflow
325 timeout = 2 * ((1<<xdev.wdt_interval) / *pfreq);
327 if (!request_mem_region(xdev.res.start,
328 xdev.res.end - xdev.res.start + 1, WATCHDOG_NAME)) {
330 pr_err("memory request failure!\n");
334 xdev.base = ioremap(xdev.res.start, xdev.res.end - xdev.res.start + 1);
335 if (xdev.base == NULL) {
337 pr_err("ioremap failure!\n");
341 rc = xwdt_selftest();
342 if (rc == XWT_TIMER_FAILED) {
343 pr_err("SelfTest routine error!\n");
347 xwdt_get_status(&xdev.boot_status);
349 rc = misc_register(&xwdt_miscdev);
351 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
352 xwdt_miscdev.minor, rc);
357 pr_info("driver loaded (timeout=? sec, nowayout=%d)\n",
360 pr_info("driver loaded (timeout=%d sec, nowayout=%d)\n",
361 timeout, xdev.nowayout);
364 clear_bit(0, &driver_open);
371 release_mem_region(xdev.res.start, resource_size(&xdev.res));
376 static int xwdt_remove(struct platform_device *dev)
378 misc_deregister(&xwdt_miscdev);
380 release_mem_region(xdev.res.start, resource_size(&xdev.res));
385 /* Match table for of_platform binding */
386 static struct of_device_id xwdt_of_match[] = {
387 { .compatible = "xlnx,xps-timebase-wdt-1.00.a", },
388 { .compatible = "xlnx,xps-timebase-wdt-1.01.a", },
391 MODULE_DEVICE_TABLE(of, xwdt_of_match);
393 static struct platform_driver xwdt_driver = {
395 .remove = xwdt_remove,
397 .owner = THIS_MODULE,
398 .name = WATCHDOG_NAME,
399 .of_match_table = xwdt_of_match,
403 module_platform_driver(xwdt_driver);
405 MODULE_AUTHOR("Alejandro Cabrera <aldaya@gmail.com>");
406 MODULE_DESCRIPTION("Xilinx Watchdog driver");
407 MODULE_LICENSE("GPL v2");