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