2 * drivers/char/watchdog/sp805-wdt.c
4 * Watchdog driver for ARM SP805 watchdog module
6 * Copyright (C) 2010 ST Microelectronics
7 * Viresh Kumar<viresh.kumar@st.com>
9 * This file is licensed under the terms of the GNU General Public
10 * License version 2 or later. This program is licensed "as is" without any
11 * warranty of any kind, whether express or implied.
14 #include <linux/device.h>
15 #include <linux/resource.h>
16 #include <linux/amba/bus.h>
17 #include <linux/bitops.h>
18 #include <linux/clk.h>
20 #include <linux/init.h>
22 #include <linux/ioport.h>
23 #include <linux/kernel.h>
24 #include <linux/math64.h>
25 #include <linux/miscdevice.h>
26 #include <linux/module.h>
27 #include <linux/moduleparam.h>
28 #include <linux/slab.h>
29 #include <linux/spinlock.h>
30 #include <linux/types.h>
31 #include <linux/uaccess.h>
32 #include <linux/watchdog.h>
34 /* default timeout in seconds */
35 #define DEFAULT_TIMEOUT 60
37 #define MODULE_NAME "sp805-wdt"
39 /* watchdog register offsets and masks */
41 #define LOAD_MIN 0x00000001
42 #define LOAD_MAX 0xFFFFFFFF
43 #define WDTVALUE 0x004
44 #define WDTCONTROL 0x008
45 /* control register masks */
46 #define INT_ENABLE (1 << 0)
47 #define RESET_ENABLE (1 << 1)
48 #define WDTINTCLR 0x00C
51 #define INT_MASK (1 << 0)
53 #define UNLOCK 0x1ACCE551
54 #define LOCK 0x00000001
57 * struct sp805_wdt: sp805 wdt device structure
59 * lock: spin lock protecting dev structure and io access
60 * base: base address of wdt
61 * clk: clock structure of wdt
62 * dev: amba device structure of wdt
63 * status: current status of wdt
64 * load_val: load value to be set for current timeout
65 * timeout: current programmed timeout
71 struct amba_device *adev;
74 #define WDT_CAN_BE_CLOSED 1
75 unsigned int load_val;
80 static struct sp805_wdt *wdt;
81 static int nowayout = WATCHDOG_NOWAYOUT;
83 /* This routine finds load value that will reset system in required timout */
84 static void wdt_setload(unsigned int timeout)
88 rate = clk_get_rate(wdt->clk);
91 * sp805 runs counter with given value twice, after the end of first
92 * counter it gives an interrupt and then starts counter again. If
93 * interrupt already occurred then it resets the system. This is why
94 * load is half of what should be required.
96 load = div_u64(rate, 2) * timeout - 1;
98 load = (load > LOAD_MAX) ? LOAD_MAX : load;
99 load = (load < LOAD_MIN) ? LOAD_MIN : load;
101 spin_lock(&wdt->lock);
102 wdt->load_val = load;
103 /* roundup timeout to closest positive integer value */
104 wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
105 spin_unlock(&wdt->lock);
108 /* returns number of seconds left for reset to occur */
109 static u32 wdt_timeleft(void)
113 rate = clk_get_rate(wdt->clk);
115 spin_lock(&wdt->lock);
116 load = readl(wdt->base + WDTVALUE);
118 /*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
119 if (!(readl(wdt->base + WDTRIS) & INT_MASK))
120 load += wdt->load_val + 1;
121 spin_unlock(&wdt->lock);
123 return div_u64(load, rate);
126 /* enables watchdog timers reset */
127 static void wdt_enable(void)
129 spin_lock(&wdt->lock);
131 writel(UNLOCK, wdt->base + WDTLOCK);
132 writel(wdt->load_val, wdt->base + WDTLOAD);
133 writel(INT_MASK, wdt->base + WDTINTCLR);
134 writel(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
135 writel(LOCK, wdt->base + WDTLOCK);
137 /* Flush posted writes. */
138 readl(wdt->base + WDTLOCK);
139 spin_unlock(&wdt->lock);
142 /* disables watchdog timers reset */
143 static void wdt_disable(void)
145 spin_lock(&wdt->lock);
147 writel(UNLOCK, wdt->base + WDTLOCK);
148 writel(0, wdt->base + WDTCONTROL);
149 writel(LOCK, wdt->base + WDTLOCK);
151 /* Flush posted writes. */
152 readl(wdt->base + WDTLOCK);
153 spin_unlock(&wdt->lock);
156 static ssize_t sp805_wdt_write(struct file *file, const char *data,
157 size_t len, loff_t *ppos)
163 clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
165 for (i = 0; i != len; i++) {
168 if (get_user(c, data + i))
170 /* Check for Magic Close character */
172 set_bit(WDT_CAN_BE_CLOSED,
183 static const struct watchdog_info ident = {
184 .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
185 .identity = MODULE_NAME,
188 static long sp805_wdt_ioctl(struct file *file, unsigned int cmd,
192 unsigned int timeout;
195 case WDIOC_GETSUPPORT:
196 ret = copy_to_user((struct watchdog_info *)arg, &ident,
197 sizeof(ident)) ? -EFAULT : 0;
200 case WDIOC_GETSTATUS:
201 ret = put_user(0, (int *)arg);
204 case WDIOC_KEEPALIVE:
209 case WDIOC_SETTIMEOUT:
210 ret = get_user(timeout, (unsigned int *)arg);
214 wdt_setload(timeout);
219 case WDIOC_GETTIMEOUT:
220 ret = put_user(wdt->timeout, (unsigned int *)arg);
222 case WDIOC_GETTIMELEFT:
223 ret = put_user(wdt_timeleft(), (unsigned int *)arg);
229 static int sp805_wdt_open(struct inode *inode, struct file *file)
233 if (test_and_set_bit(WDT_BUSY, &wdt->status))
236 ret = clk_enable(wdt->clk);
238 dev_err(&wdt->adev->dev, "clock enable fail");
244 /* can not be closed, once enabled */
245 clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
246 return nonseekable_open(inode, file);
249 clear_bit(WDT_BUSY, &wdt->status);
253 static int sp805_wdt_release(struct inode *inode, struct file *file)
255 if (!test_bit(WDT_CAN_BE_CLOSED, &wdt->status)) {
256 clear_bit(WDT_BUSY, &wdt->status);
257 dev_warn(&wdt->adev->dev, "Device closed unexpectedly\n");
262 clk_disable(wdt->clk);
263 clear_bit(WDT_BUSY, &wdt->status);
268 static const struct file_operations sp805_wdt_fops = {
269 .owner = THIS_MODULE,
271 .write = sp805_wdt_write,
272 .unlocked_ioctl = sp805_wdt_ioctl,
273 .open = sp805_wdt_open,
274 .release = sp805_wdt_release,
277 static struct miscdevice sp805_wdt_miscdev = {
278 .minor = WATCHDOG_MINOR,
280 .fops = &sp805_wdt_fops,
284 sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
288 if (!request_mem_region(adev->res.start, resource_size(&adev->res),
290 dev_warn(&adev->dev, "Failed to get memory region resource\n");
295 wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
297 dev_warn(&adev->dev, "Kzalloc failed\n");
302 wdt->clk = clk_get(&adev->dev, NULL);
303 if (IS_ERR(wdt->clk)) {
304 dev_warn(&adev->dev, "Clock not found\n");
305 ret = PTR_ERR(wdt->clk);
309 wdt->base = ioremap(adev->res.start, resource_size(&adev->res));
312 dev_warn(&adev->dev, "ioremap fail\n");
317 spin_lock_init(&wdt->lock);
318 wdt_setload(DEFAULT_TIMEOUT);
320 ret = misc_register(&sp805_wdt_miscdev);
322 dev_warn(&adev->dev, "cannot register misc device\n");
323 goto err_misc_register;
326 dev_info(&adev->dev, "registration successful\n");
337 release_mem_region(adev->res.start, resource_size(&adev->res));
339 dev_err(&adev->dev, "Probe Failed!!!\n");
343 static int __devexit sp805_wdt_remove(struct amba_device *adev)
345 misc_deregister(&sp805_wdt_miscdev);
349 release_mem_region(adev->res.start, resource_size(&adev->res));
354 static struct amba_id sp805_wdt_ids[] = {
362 MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);
364 static struct amba_driver sp805_wdt_driver = {
368 .id_table = sp805_wdt_ids,
369 .probe = sp805_wdt_probe,
370 .remove = __devexit_p(sp805_wdt_remove),
373 static int __init sp805_wdt_init(void)
375 return amba_driver_register(&sp805_wdt_driver);
377 module_init(sp805_wdt_init);
379 static void __exit sp805_wdt_exit(void)
381 amba_driver_unregister(&sp805_wdt_driver);
383 module_exit(sp805_wdt_exit);
385 module_param(nowayout, int, 0);
386 MODULE_PARM_DESC(nowayout,
387 "Set to 1 to keep watchdog running after device release");
389 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@st.com>");
390 MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
391 MODULE_LICENSE("GPL");
392 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);