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