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19#define pr_fmt(fmt) "dw_wdt: " fmt
20
21#include <linux/bitops.h>
22#include <linux/clk.h>
23#include <linux/device.h>
24#include <linux/err.h>
25#include <linux/fs.h>
26#include <linux/io.h>
27#include <linux/kernel.h>
28#include <linux/miscdevice.h>
29#include <linux/module.h>
30#include <linux/moduleparam.h>
31#include <linux/pm.h>
32#include <linux/platform_device.h>
33#include <linux/spinlock.h>
34#include <linux/timer.h>
35#include <linux/uaccess.h>
36#include <linux/watchdog.h>
37
38#define WDOG_CONTROL_REG_OFFSET 0x00
39#define WDOG_CONTROL_REG_WDT_EN_MASK 0x01
40#define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04
41#define WDOG_CURRENT_COUNT_REG_OFFSET 0x08
42#define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c
43#define WDOG_COUNTER_RESTART_KICK_VALUE 0x76
44
45
46#define DW_WDT_MAX_TOP 15
47
48static int nowayout = WATCHDOG_NOWAYOUT;
49module_param(nowayout, int, 0);
50MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
51 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
52
53#define WDT_TIMEOUT (HZ / 2)
54
55static struct {
56 spinlock_t lock;
57 void __iomem *regs;
58 struct clk *clk;
59 unsigned long in_use;
60 unsigned long next_heartbeat;
61 struct timer_list timer;
62 int expect_close;
63} dw_wdt;
64
65static inline int dw_wdt_is_enabled(void)
66{
67 return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
68 WDOG_CONTROL_REG_WDT_EN_MASK;
69}
70
71static inline int dw_wdt_top_in_seconds(unsigned top)
72{
73
74
75
76
77 return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk);
78}
79
80static int dw_wdt_get_top(void)
81{
82 int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
83
84 return dw_wdt_top_in_seconds(top);
85}
86
87static inline void dw_wdt_set_next_heartbeat(void)
88{
89 dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
90}
91
92static int dw_wdt_set_top(unsigned top_s)
93{
94 int i, top_val = DW_WDT_MAX_TOP;
95
96
97
98
99
100 for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
101 if (dw_wdt_top_in_seconds(i) >= top_s) {
102 top_val = i;
103 break;
104 }
105
106
107 writel(top_val, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
108
109 dw_wdt_set_next_heartbeat();
110
111 return dw_wdt_top_in_seconds(top_val);
112}
113
114static void dw_wdt_keepalive(void)
115{
116 writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
117 WDOG_COUNTER_RESTART_REG_OFFSET);
118}
119
120static void dw_wdt_ping(unsigned long data)
121{
122 if (time_before(jiffies, dw_wdt.next_heartbeat) ||
123 (!nowayout && !dw_wdt.in_use)) {
124 dw_wdt_keepalive();
125 mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
126 } else
127 pr_crit("keepalive missed, machine will reset\n");
128}
129
130static int dw_wdt_open(struct inode *inode, struct file *filp)
131{
132 if (test_and_set_bit(0, &dw_wdt.in_use))
133 return -EBUSY;
134
135
136 __module_get(THIS_MODULE);
137
138 spin_lock(&dw_wdt.lock);
139 if (!dw_wdt_is_enabled()) {
140
141
142
143
144 dw_wdt_set_top(DW_WDT_MAX_TOP);
145 writel(WDOG_CONTROL_REG_WDT_EN_MASK,
146 dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
147 }
148
149 dw_wdt_set_next_heartbeat();
150
151 spin_unlock(&dw_wdt.lock);
152
153 return nonseekable_open(inode, filp);
154}
155
156ssize_t dw_wdt_write(struct file *filp, const char __user *buf, size_t len,
157 loff_t *offset)
158{
159 if (!len)
160 return 0;
161
162 if (!nowayout) {
163 size_t i;
164
165 dw_wdt.expect_close = 0;
166
167 for (i = 0; i < len; ++i) {
168 char c;
169
170 if (get_user(c, buf + i))
171 return -EFAULT;
172
173 if (c == 'V') {
174 dw_wdt.expect_close = 1;
175 break;
176 }
177 }
178 }
179
180 dw_wdt_set_next_heartbeat();
181 mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
182
183 return len;
184}
185
186static u32 dw_wdt_time_left(void)
187{
188 return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
189 clk_get_rate(dw_wdt.clk);
190}
191
192static const struct watchdog_info dw_wdt_ident = {
193 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
194 WDIOF_MAGICCLOSE,
195 .identity = "Synopsys DesignWare Watchdog",
196};
197
198static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
199{
200 unsigned long val;
201 int timeout;
202
203 switch (cmd) {
204 case WDIOC_GETSUPPORT:
205 return copy_to_user((struct watchdog_info *)arg, &dw_wdt_ident,
206 sizeof(dw_wdt_ident)) ? -EFAULT : 0;
207
208 case WDIOC_GETSTATUS:
209 case WDIOC_GETBOOTSTATUS:
210 return put_user(0, (int *)arg);
211
212 case WDIOC_KEEPALIVE:
213 dw_wdt_set_next_heartbeat();
214 return 0;
215
216 case WDIOC_SETTIMEOUT:
217 if (get_user(val, (int __user *)arg))
218 return -EFAULT;
219 timeout = dw_wdt_set_top(val);
220 return put_user(timeout , (int __user *)arg);
221
222 case WDIOC_GETTIMEOUT:
223 return put_user(dw_wdt_get_top(), (int __user *)arg);
224
225 case WDIOC_GETTIMELEFT:
226
227 if (get_user(val, (int __user *)arg))
228 return -EFAULT;
229 return put_user(dw_wdt_time_left(), (int __user *)arg);
230
231 default:
232 return -ENOTTY;
233 }
234}
235
236static int dw_wdt_release(struct inode *inode, struct file *filp)
237{
238 clear_bit(0, &dw_wdt.in_use);
239
240 if (!dw_wdt.expect_close) {
241 del_timer(&dw_wdt.timer);
242
243 if (!nowayout)
244 pr_crit("unexpected close, system will reboot soon\n");
245 else
246 pr_crit("watchdog cannot be disabled, system will reboot soon\n");
247 }
248
249 dw_wdt.expect_close = 0;
250
251 return 0;
252}
253
254#ifdef CONFIG_PM
255static int dw_wdt_suspend(struct device *dev)
256{
257 clk_disable(dw_wdt.clk);
258
259 return 0;
260}
261
262static int dw_wdt_resume(struct device *dev)
263{
264 int err = clk_enable(dw_wdt.clk);
265
266 if (err)
267 return err;
268
269 dw_wdt_keepalive();
270
271 return 0;
272}
273
274static const struct dev_pm_ops dw_wdt_pm_ops = {
275 .suspend = dw_wdt_suspend,
276 .resume = dw_wdt_resume,
277};
278#endif
279
280static const struct file_operations wdt_fops = {
281 .owner = THIS_MODULE,
282 .llseek = no_llseek,
283 .open = dw_wdt_open,
284 .write = dw_wdt_write,
285 .unlocked_ioctl = dw_wdt_ioctl,
286 .release = dw_wdt_release
287};
288
289static struct miscdevice dw_wdt_miscdev = {
290 .fops = &wdt_fops,
291 .name = "watchdog",
292 .minor = WATCHDOG_MINOR,
293};
294
295static int __devinit dw_wdt_drv_probe(struct platform_device *pdev)
296{
297 int ret;
298 struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
299
300 if (!mem)
301 return -EINVAL;
302
303 dw_wdt.regs = devm_request_and_ioremap(&pdev->dev, mem);
304 if (!dw_wdt.regs)
305 return -ENOMEM;
306
307 dw_wdt.clk = clk_get(&pdev->dev, NULL);
308 if (IS_ERR(dw_wdt.clk))
309 return PTR_ERR(dw_wdt.clk);
310
311 ret = clk_enable(dw_wdt.clk);
312 if (ret)
313 goto out_put_clk;
314
315 spin_lock_init(&dw_wdt.lock);
316
317 ret = misc_register(&dw_wdt_miscdev);
318 if (ret)
319 goto out_disable_clk;
320
321 dw_wdt_set_next_heartbeat();
322 setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
323 mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
324
325 return 0;
326
327out_disable_clk:
328 clk_disable(dw_wdt.clk);
329out_put_clk:
330 clk_put(dw_wdt.clk);
331
332 return ret;
333}
334
335static int __devexit dw_wdt_drv_remove(struct platform_device *pdev)
336{
337 misc_deregister(&dw_wdt_miscdev);
338
339 clk_disable(dw_wdt.clk);
340 clk_put(dw_wdt.clk);
341
342 return 0;
343}
344
345static struct platform_driver dw_wdt_driver = {
346 .probe = dw_wdt_drv_probe,
347 .remove = __devexit_p(dw_wdt_drv_remove),
348 .driver = {
349 .name = "dw_wdt",
350 .owner = THIS_MODULE,
351#ifdef CONFIG_PM
352 .pm = &dw_wdt_pm_ops,
353#endif
354 },
355};
356
357module_platform_driver(dw_wdt_driver);
358
359MODULE_AUTHOR("Jamie Iles");
360MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
361MODULE_LICENSE("GPL");
362MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
363
