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Viresh KUMAR4a370272010-08-04 11:44:14 +05301/*
2 * drivers/char/watchdog/sp805-wdt.c
3 *
4 * Watchdog driver for ARM SP805 watchdog module
5 *
6 * Copyright (C) 2010 ST Microelectronics
7 * Viresh Kumar<viresh.kumar@st.com>
8 *
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.
12 */
13
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>
19#include <linux/fs.h>
20#include <linux/init.h>
21#include <linux/io.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>
33
34/* default timeout in seconds */
35#define DEFAULT_TIMEOUT 60
36
37#define MODULE_NAME "sp805-wdt"
38
39/* watchdog register offsets and masks */
40#define WDTLOAD 0x000
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
49#define WDTRIS 0x010
50#define WDTMIS 0x014
51 #define INT_MASK (1 << 0)
52#define WDTLOCK 0xC00
53 #define UNLOCK 0x1ACCE551
54 #define LOCK 0x00000001
55
56/**
57 * struct sp805_wdt: sp805 wdt device structure
58 *
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
66 */
67struct sp805_wdt {
68 spinlock_t lock;
69 void __iomem *base;
70 struct clk *clk;
71 struct amba_device *adev;
72 unsigned long status;
73 #define WDT_BUSY 0
74 #define WDT_CAN_BE_CLOSED 1
75 unsigned int load_val;
76 unsigned int timeout;
77};
78
79/* local variables */
80static struct sp805_wdt *wdt;
81static int nowayout = WATCHDOG_NOWAYOUT;
82
83/* This routine finds load value that will reset system in required timout */
84static void wdt_setload(unsigned int timeout)
85{
86 u64 load, rate;
87
88 rate = clk_get_rate(wdt->clk);
89
90 /*
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
Lucas De Marchi25985ed2011-03-30 22:57:33 -030093 * interrupt already occurred then it resets the system. This is why
Viresh KUMAR4a370272010-08-04 11:44:14 +053094 * load is half of what should be required.
95 */
96 load = div_u64(rate, 2) * timeout - 1;
97
98 load = (load > LOAD_MAX) ? LOAD_MAX : load;
99 load = (load < LOAD_MIN) ? LOAD_MIN : load;
100
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);
106}
107
108/* returns number of seconds left for reset to occur */
109static u32 wdt_timeleft(void)
110{
111 u64 load, rate;
112
113 rate = clk_get_rate(wdt->clk);
114
115 spin_lock(&wdt->lock);
116 load = readl(wdt->base + WDTVALUE);
117
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);
122
123 return div_u64(load, rate);
124}
125
126/* enables watchdog timers reset */
127static void wdt_enable(void)
128{
129 spin_lock(&wdt->lock);
130
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);
136
Nick Bowler081d83a2011-07-15 11:04:02 -0400137 /* Flush posted writes. */
138 readl(wdt->base + WDTLOCK);
Viresh KUMAR4a370272010-08-04 11:44:14 +0530139 spin_unlock(&wdt->lock);
140}
141
142/* disables watchdog timers reset */
143static void wdt_disable(void)
144{
145 spin_lock(&wdt->lock);
146
147 writel(UNLOCK, wdt->base + WDTLOCK);
148 writel(0, wdt->base + WDTCONTROL);
Viresh KUMAR4a370272010-08-04 11:44:14 +0530149 writel(LOCK, wdt->base + WDTLOCK);
150
Nick Bowler081d83a2011-07-15 11:04:02 -0400151 /* Flush posted writes. */
152 readl(wdt->base + WDTLOCK);
Viresh KUMAR4a370272010-08-04 11:44:14 +0530153 spin_unlock(&wdt->lock);
154}
155
156static ssize_t sp805_wdt_write(struct file *file, const char *data,
157 size_t len, loff_t *ppos)
158{
159 if (len) {
160 if (!nowayout) {
161 size_t i;
162
163 clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
164
165 for (i = 0; i != len; i++) {
166 char c;
167
168 if (get_user(c, data + i))
169 return -EFAULT;
170 /* Check for Magic Close character */
171 if (c == 'V') {
172 set_bit(WDT_CAN_BE_CLOSED,
173 &wdt->status);
174 break;
175 }
176 }
177 }
178 wdt_enable();
179 }
180 return len;
181}
182
183static const struct watchdog_info ident = {
184 .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
185 .identity = MODULE_NAME,
186};
187
188static long sp805_wdt_ioctl(struct file *file, unsigned int cmd,
189 unsigned long arg)
190{
191 int ret = -ENOTTY;
192 unsigned int timeout;
193
194 switch (cmd) {
195 case WDIOC_GETSUPPORT:
196 ret = copy_to_user((struct watchdog_info *)arg, &ident,
197 sizeof(ident)) ? -EFAULT : 0;
198 break;
199
200 case WDIOC_GETSTATUS:
201 ret = put_user(0, (int *)arg);
202 break;
203
204 case WDIOC_KEEPALIVE:
205 wdt_enable();
206 ret = 0;
207 break;
208
209 case WDIOC_SETTIMEOUT:
210 ret = get_user(timeout, (unsigned int *)arg);
211 if (ret)
212 break;
213
214 wdt_setload(timeout);
215
216 wdt_enable();
217 /* Fall through */
218
219 case WDIOC_GETTIMEOUT:
220 ret = put_user(wdt->timeout, (unsigned int *)arg);
221 break;
222 case WDIOC_GETTIMELEFT:
223 ret = put_user(wdt_timeleft(), (unsigned int *)arg);
224 break;
225 }
226 return ret;
227}
228
229static int sp805_wdt_open(struct inode *inode, struct file *file)
230{
231 int ret = 0;
232
233 if (test_and_set_bit(WDT_BUSY, &wdt->status))
234 return -EBUSY;
235
236 ret = clk_enable(wdt->clk);
237 if (ret) {
238 dev_err(&wdt->adev->dev, "clock enable fail");
239 goto err;
240 }
241
242 wdt_enable();
243
244 /* can not be closed, once enabled */
245 clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
246 return nonseekable_open(inode, file);
247
248err:
249 clear_bit(WDT_BUSY, &wdt->status);
250 return ret;
251}
252
253static int sp805_wdt_release(struct inode *inode, struct file *file)
254{
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");
258 return 0;
259 }
260
261 wdt_disable();
262 clk_disable(wdt->clk);
263 clear_bit(WDT_BUSY, &wdt->status);
264
265 return 0;
266}
267
268static const struct file_operations sp805_wdt_fops = {
269 .owner = THIS_MODULE,
270 .llseek = no_llseek,
271 .write = sp805_wdt_write,
272 .unlocked_ioctl = sp805_wdt_ioctl,
273 .open = sp805_wdt_open,
274 .release = sp805_wdt_release,
275};
276
277static struct miscdevice sp805_wdt_miscdev = {
278 .minor = WATCHDOG_MINOR,
279 .name = "watchdog",
280 .fops = &sp805_wdt_fops,
281};
282
283static int __devinit
Russell Kingaa25afa2011-02-19 15:55:00 +0000284sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
Viresh KUMAR4a370272010-08-04 11:44:14 +0530285{
286 int ret = 0;
287
288 if (!request_mem_region(adev->res.start, resource_size(&adev->res),
289 "sp805_wdt")) {
290 dev_warn(&adev->dev, "Failed to get memory region resource\n");
291 ret = -ENOENT;
292 goto err;
293 }
294
295 wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
296 if (!wdt) {
297 dev_warn(&adev->dev, "Kzalloc failed\n");
298 ret = -ENOMEM;
299 goto err_kzalloc;
300 }
301
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);
306 goto err_clk_get;
307 }
308
309 wdt->base = ioremap(adev->res.start, resource_size(&adev->res));
310 if (!wdt->base) {
311 ret = -ENOMEM;
312 dev_warn(&adev->dev, "ioremap fail\n");
313 goto err_ioremap;
314 }
315
316 wdt->adev = adev;
317 spin_lock_init(&wdt->lock);
318 wdt_setload(DEFAULT_TIMEOUT);
319
320 ret = misc_register(&sp805_wdt_miscdev);
321 if (ret < 0) {
322 dev_warn(&adev->dev, "cannot register misc device\n");
323 goto err_misc_register;
324 }
325
326 dev_info(&adev->dev, "registration successful\n");
327 return 0;
328
329err_misc_register:
330 iounmap(wdt->base);
331err_ioremap:
332 clk_put(wdt->clk);
333err_clk_get:
334 kfree(wdt);
335 wdt = NULL;
336err_kzalloc:
337 release_mem_region(adev->res.start, resource_size(&adev->res));
338err:
339 dev_err(&adev->dev, "Probe Failed!!!\n");
340 return ret;
341}
342
343static int __devexit sp805_wdt_remove(struct amba_device *adev)
344{
345 misc_deregister(&sp805_wdt_miscdev);
346 iounmap(wdt->base);
347 clk_put(wdt->clk);
348 kfree(wdt);
349 release_mem_region(adev->res.start, resource_size(&adev->res));
350
351 return 0;
352}
353
354static struct amba_id sp805_wdt_ids[] __initdata = {
355 {
356 .id = 0x00141805,
357 .mask = 0x00ffffff,
358 },
359 { 0, 0 },
360};
361
362static struct amba_driver sp805_wdt_driver = {
363 .drv = {
364 .name = MODULE_NAME,
365 },
366 .id_table = sp805_wdt_ids,
367 .probe = sp805_wdt_probe,
368 .remove = __devexit_p(sp805_wdt_remove),
369};
370
371static int __init sp805_wdt_init(void)
372{
373 return amba_driver_register(&sp805_wdt_driver);
374}
375module_init(sp805_wdt_init);
376
377static void __exit sp805_wdt_exit(void)
378{
379 amba_driver_unregister(&sp805_wdt_driver);
380}
381module_exit(sp805_wdt_exit);
382
383module_param(nowayout, int, 0);
384MODULE_PARM_DESC(nowayout,
385 "Set to 1 to keep watchdog running after device release");
386
387MODULE_AUTHOR("Viresh Kumar <viresh.kumar@st.com>");
388MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
389MODULE_LICENSE("GPL");
390MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);