[WATCHDOG] Add watchdog driver for NUC900
[linux-2.6.git] / drivers / watchdog / nuc900_wdt.c
1 /*
2  * Copyright (c) 2009 Nuvoton technology corporation.
3  *
4  * Wan ZongShun <mcuos.com@gmail.com>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation;version 2 of the License.
9  *
10  */
11
12 #include <linux/bitops.h>
13 #include <linux/errno.h>
14 #include <linux/fs.h>
15 #include <linux/init.h>
16 #include <linux/io.h>
17 #include <linux/clk.h>
18 #include <linux/kernel.h>
19 #include <linux/miscdevice.h>
20 #include <linux/module.h>
21 #include <linux/moduleparam.h>
22 #include <linux/platform_device.h>
23 #include <linux/interrupt.h>
24 #include <linux/types.h>
25 #include <linux/watchdog.h>
26 #include <linux/uaccess.h>
27
28 #define REG_WTCR                0x1c
29 #define WTCLK                   (0x01 << 10)
30 #define WTE                     (0x01 << 7)     /*wdt enable*/
31 #define WTIS                    (0x03 << 4)
32 #define WTIF                    (0x01 << 3)
33 #define WTRF                    (0x01 << 2)
34 #define WTRE                    (0x01 << 1)
35 #define WTR                     (0x01 << 0)
36 /*
37  * The watchdog time interval can be calculated via following formula:
38  * WTIS         real time interval (formula)
39  * 0x00         ((2^ 14 ) * ((external crystal freq) / 256))seconds
40  * 0x01         ((2^ 16 ) * ((external crystal freq) / 256))seconds
41  * 0x02         ((2^ 18 ) * ((external crystal freq) / 256))seconds
42  * 0x03         ((2^ 20 ) * ((external crystal freq) / 256))seconds
43  *
44  * The external crystal freq is 15Mhz in the nuc900 evaluation board.
45  * So 0x00 = +-0.28 seconds, 0x01 = +-1.12 seconds, 0x02 = +-4.48 seconds,
46  * 0x03 = +- 16.92 seconds..
47  */
48 #define WDT_HW_TIMEOUT          0x02
49 #define WDT_TIMEOUT             (HZ/2)
50 #define WDT_HEARTBEAT           15
51
52 static int heartbeat = WDT_HEARTBEAT;
53 module_param(heartbeat, int, 0);
54 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
55         "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
56
57 static int nowayout = WATCHDOG_NOWAYOUT;
58 module_param(nowayout, int, 0);
59 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
60         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
61
62 struct nuc900_wdt {
63         struct resource  *res;
64         struct clk       *wdt_clock;
65         struct platform_device *pdev;
66         void __iomem     *wdt_base;
67         char             expect_close;
68         struct timer_list timer;
69         spinlock_t       wdt_lock;
70         unsigned long next_heartbeat;
71 };
72
73 static unsigned long nuc900wdt_busy;
74 struct nuc900_wdt *nuc900_wdt;
75
76 static inline void nuc900_wdt_keepalive(void)
77 {
78         unsigned int val;
79
80         spin_lock(&nuc900_wdt->wdt_lock);
81
82         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
83         val |= (WTR | WTIF);
84         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
85
86         spin_unlock(&nuc900_wdt->wdt_lock);
87 }
88
89 static inline void nuc900_wdt_start(void)
90 {
91         unsigned int val;
92
93         spin_lock(&nuc900_wdt->wdt_lock);
94
95         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
96         val |= (WTRE | WTE | WTR | WTCLK | WTIF);
97         val &= ~WTIS;
98         val |= (WDT_HW_TIMEOUT << 0x04);
99         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
100
101         spin_unlock(&nuc900_wdt->wdt_lock);
102
103         nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
104         mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
105 }
106
107 static inline void nuc900_wdt_stop(void)
108 {
109         unsigned int val;
110
111         del_timer(&nuc900_wdt->timer);
112
113         spin_lock(&nuc900_wdt->wdt_lock);
114
115         val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
116         val &= ~WTE;
117         __raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);
118
119         spin_unlock(&nuc900_wdt->wdt_lock);
120 }
121
122 static inline void nuc900_wdt_ping(void)
123 {
124         nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
125 }
126
127 static int nuc900_wdt_open(struct inode *inode, struct file *file)
128 {
129
130         if (test_and_set_bit(0, &nuc900wdt_busy))
131                 return -EBUSY;
132
133         nuc900_wdt_start();
134
135         return nonseekable_open(inode, file);
136 }
137
138 static int nuc900_wdt_close(struct inode *inode, struct file *file)
139 {
140         if (nuc900_wdt->expect_close == 42)
141                 nuc900_wdt_stop();
142         else {
143                 dev_crit(&nuc900_wdt->pdev->dev,
144                         "Unexpected close, not stopping watchdog!\n");
145                 nuc900_wdt_ping();
146         }
147
148         nuc900_wdt->expect_close = 0;
149         clear_bit(0, &nuc900wdt_busy);
150         return 0;
151 }
152
153 static const struct watchdog_info nuc900_wdt_info = {
154         .identity       = "nuc900 watchdog",
155         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
156                                                 WDIOF_MAGICCLOSE,
157 };
158
159 static long nuc900_wdt_ioctl(struct file *file,
160                                         unsigned int cmd, unsigned long arg)
161 {
162         void __user *argp = (void __user *)arg;
163         int __user *p = argp;
164         int new_value;
165
166         switch (cmd) {
167         case WDIOC_GETSUPPORT:
168                 return copy_to_user(argp, &nuc900_wdt_info,
169                                 sizeof(nuc900_wdt_info)) ? -EFAULT : 0;
170         case WDIOC_GETSTATUS:
171         case WDIOC_GETBOOTSTATUS:
172                 return put_user(0, p);
173
174         case WDIOC_KEEPALIVE:
175                 nuc900_wdt_ping();
176                 return 0;
177
178         case WDIOC_SETTIMEOUT:
179                 if (get_user(new_value, p))
180                         return -EFAULT;
181
182                 heartbeat = new_value;
183                 nuc900_wdt_ping();
184
185                 return put_user(new_value, p);
186         case WDIOC_GETTIMEOUT:
187                 return put_user(heartbeat, p);
188         default:
189                 return -ENOTTY;
190         }
191 }
192
193 static ssize_t nuc900_wdt_write(struct file *file, const char __user *data,
194                                                 size_t len, loff_t *ppos)
195 {
196         if (!len)
197                 return 0;
198
199         /* Scan for magic character */
200         if (!nowayout) {
201                 size_t i;
202
203                 nuc900_wdt->expect_close = 0;
204
205                 for (i = 0; i < len; i++) {
206                         char c;
207                         if (get_user(c, data + i))
208                                 return -EFAULT;
209                         if (c == 'V') {
210                                 nuc900_wdt->expect_close = 42;
211                                 break;
212                         }
213                 }
214         }
215
216         nuc900_wdt_ping();
217         return len;
218 }
219
220 static void nuc900_wdt_timer_ping(unsigned long data)
221 {
222         if (time_before(jiffies, nuc900_wdt->next_heartbeat)) {
223                 nuc900_wdt_keepalive();
224                 mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
225         } else
226                 dev_warn(&nuc900_wdt->pdev->dev, "Will reset the machine !\n");
227 }
228
229 static const struct file_operations nuc900wdt_fops = {
230         .owner          = THIS_MODULE,
231         .llseek         = no_llseek,
232         .unlocked_ioctl = nuc900_wdt_ioctl,
233         .open           = nuc900_wdt_open,
234         .release        = nuc900_wdt_close,
235         .write          = nuc900_wdt_write,
236 };
237
238 static struct miscdevice nuc900wdt_miscdev = {
239         .minor          = WATCHDOG_MINOR,
240         .name           = "watchdog",
241         .fops           = &nuc900wdt_fops,
242 };
243
244 static int __devinit nuc900wdt_probe(struct platform_device *pdev)
245 {
246         int ret = 0;
247
248         nuc900_wdt = kzalloc(sizeof(struct nuc900_wdt), GFP_KERNEL);
249         if (!nuc900_wdt)
250                 return -ENOMEM;
251
252         nuc900_wdt->pdev = pdev;
253
254         spin_lock_init(&nuc900_wdt->wdt_lock);
255
256         nuc900_wdt->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
257         if (nuc900_wdt->res == NULL) {
258                 dev_err(&pdev->dev, "no memory resource specified\n");
259                 ret = -ENOENT;
260                 goto err_get;
261         }
262
263         if (!request_mem_region(nuc900_wdt->res->start,
264                                 resource_size(nuc900_wdt->res), pdev->name)) {
265                 dev_err(&pdev->dev, "failed to get memory region\n");
266                 ret = -ENOENT;
267                 goto err_get;
268         }
269
270         nuc900_wdt->wdt_base = ioremap(nuc900_wdt->res->start,
271                                         resource_size(nuc900_wdt->res));
272         if (nuc900_wdt->wdt_base == NULL) {
273                 dev_err(&pdev->dev, "failed to ioremap() region\n");
274                 ret = -EINVAL;
275                 goto err_req;
276         }
277
278         nuc900_wdt->wdt_clock = clk_get(&pdev->dev, NULL);
279         if (IS_ERR(nuc900_wdt->wdt_clock)) {
280                 dev_err(&pdev->dev, "failed to find watchdog clock source\n");
281                 ret = PTR_ERR(nuc900_wdt->wdt_clock);
282                 goto err_map;
283         }
284
285         clk_enable(nuc900_wdt->wdt_clock);
286
287         setup_timer(&nuc900_wdt->timer, nuc900_wdt_timer_ping, 0);
288
289         if (misc_register(&nuc900wdt_miscdev)) {
290                 dev_err(&pdev->dev, "err register miscdev on minor=%d (%d)\n",
291                         WATCHDOG_MINOR, ret);
292                 goto err_clk;
293         }
294
295         return 0;
296
297 err_clk:
298         clk_disable(nuc900_wdt->wdt_clock);
299         clk_put(nuc900_wdt->wdt_clock);
300 err_map:
301         iounmap(nuc900_wdt->wdt_base);
302 err_req:
303         release_mem_region(nuc900_wdt->res->start,
304                                         resource_size(nuc900_wdt->res));
305 err_get:
306         kfree(nuc900_wdt);
307         return ret;
308 }
309
310 static int __devexit nuc900wdt_remove(struct platform_device *pdev)
311 {
312         misc_deregister(&nuc900wdt_miscdev);
313
314         clk_disable(nuc900_wdt->wdt_clock);
315         clk_put(nuc900_wdt->wdt_clock);
316
317         iounmap(nuc900_wdt->wdt_base);
318
319         release_mem_region(nuc900_wdt->res->start,
320                                         resource_size(nuc900_wdt->res));
321
322         kfree(nuc900_wdt);
323
324         return 0;
325 }
326
327 static struct platform_driver nuc900wdt_driver = {
328         .probe          = nuc900wdt_probe,
329         .remove         = __devexit_p(nuc900wdt_remove),
330         .driver         = {
331                 .name   = "nuc900-wdt",
332                 .owner  = THIS_MODULE,
333         },
334 };
335
336 static int __init nuc900_wdt_init(void)
337 {
338         return platform_driver_register(&nuc900wdt_driver);
339 }
340
341 static void __exit nuc900_wdt_exit(void)
342 {
343         platform_driver_unregister(&nuc900wdt_driver);
344 }
345
346 module_init(nuc900_wdt_init);
347 module_exit(nuc900_wdt_exit);
348
349 MODULE_AUTHOR("Wan ZongShun <mcuos.com@gmail.com>");
350 MODULE_DESCRIPTION("Watchdog driver for NUC900");
351 MODULE_LICENSE("GPL");
352 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
353 MODULE_ALIAS("platform:nuc900-wdt");