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1/*
2 * Copyright 2010-2011 Picochip Ltd., Jamie Iles
3 * http://www.picochip.com
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
9 *
10 * This file implements a driver for the Synopsys DesignWare watchdog device
11 * in the many ARM subsystems. The watchdog has 16 different timeout periods
12 * and these are a function of the input clock frequency.
13 *
14 * The DesignWare watchdog cannot be stopped once it has been started so we
15 * use a software timer to implement a ping that will keep the watchdog alive.
16 * If we receive an expected close for the watchdog then we keep the timer
17 * running, otherwise the timer is stopped and the watchdog will expire.
18 */
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/* The maximum TOP (timeout period) value that can be set in the watchdog. */
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 * There are 16 possible timeout values in 0..15 where the number of
75 * cycles is 2 ^ (16 + i) and the watchdog counts down.
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 * Iterate over the timeout values until we find the closest match. We
98 * always look for >=.
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 /* Set the new value in the watchdog. */
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 /* Make sure we don't get unloaded. */
136 __module_get(THIS_MODULE);
137
138 spin_lock(&dw_wdt.lock);
139 if (!dw_wdt_is_enabled()) {
140 /*
141 * The watchdog is not currently enabled. Set the timeout to
142 * the maximum and then start it.
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 /* Get the time left until expiry. */
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 /* CONFIG_PM */
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 if (!devm_request_mem_region(&pdev->dev, mem->start, resource_size(mem),
304 "dw_wdt"))
305 return -ENOMEM;
306
307 dw_wdt.regs = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
308 if (!dw_wdt.regs)
309 return -ENOMEM;
310
311 dw_wdt.clk = clk_get(&pdev->dev, NULL);
312 if (IS_ERR(dw_wdt.clk))
313 return PTR_ERR(dw_wdt.clk);
314
315 ret = clk_enable(dw_wdt.clk);
316 if (ret)
317 goto out_put_clk;
318
319 spin_lock_init(&dw_wdt.lock);
320
321 ret = misc_register(&dw_wdt_miscdev);
322 if (ret)
323 goto out_disable_clk;
324
325 dw_wdt_set_next_heartbeat();
326 setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
327 mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
328
329 return 0;
330
331out_disable_clk:
332 clk_disable(dw_wdt.clk);
333out_put_clk:
334 clk_put(dw_wdt.clk);
335
336 return ret;
337}
338
339static int __devexit dw_wdt_drv_remove(struct platform_device *pdev)
340{
341 misc_deregister(&dw_wdt_miscdev);
342
343 clk_disable(dw_wdt.clk);
344 clk_put(dw_wdt.clk);
345
346 return 0;
347}
348
349static struct platform_driver dw_wdt_driver = {
350 .probe = dw_wdt_drv_probe,
351 .remove = __devexit_p(dw_wdt_drv_remove),
352 .driver = {
353 .name = "dw_wdt",
354 .owner = THIS_MODULE,
355#ifdef CONFIG_PM
356 .pm = &dw_wdt_pm_ops,
357#endif /* CONFIG_PM */
358 },
359};
360
361static int __init dw_wdt_watchdog_init(void)
362{
363 return platform_driver_register(&dw_wdt_driver);
364}
365module_init(dw_wdt_watchdog_init);
366
367static void __exit dw_wdt_watchdog_exit(void)
368{
369 platform_driver_unregister(&dw_wdt_driver);
370}
371module_exit(dw_wdt_watchdog_exit);
372
373MODULE_AUTHOR("Jamie Iles");
374MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
375MODULE_LICENSE("GPL");
376MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
1/*
2 * Copyright 2010-2011 Picochip Ltd., Jamie Iles
3 * http://www.picochip.com
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
9 *
10 * This file implements a driver for the Synopsys DesignWare watchdog device
11 * in the many subsystems. The watchdog has 16 different timeout periods
12 * and these are a function of the input clock frequency.
13 *
14 * The DesignWare watchdog cannot be stopped once it has been started so we
15 * do not implement a stop function. The watchdog core will continue to send
16 * heartbeat requests after the watchdog device has been closed.
17 */
18
19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21#include <linux/bitops.h>
22#include <linux/clk.h>
23#include <linux/delay.h>
24#include <linux/err.h>
25#include <linux/io.h>
26#include <linux/kernel.h>
27#include <linux/module.h>
28#include <linux/moduleparam.h>
29#include <linux/notifier.h>
30#include <linux/of.h>
31#include <linux/pm.h>
32#include <linux/platform_device.h>
33#include <linux/reboot.h>
34#include <linux/watchdog.h>
35
36#define WDOG_CONTROL_REG_OFFSET 0x00
37#define WDOG_CONTROL_REG_WDT_EN_MASK 0x01
38#define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04
39#define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT 4
40#define WDOG_CURRENT_COUNT_REG_OFFSET 0x08
41#define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c
42#define WDOG_COUNTER_RESTART_KICK_VALUE 0x76
43
44/* The maximum TOP (timeout period) value that can be set in the watchdog. */
45#define DW_WDT_MAX_TOP 15
46
47#define DW_WDT_DEFAULT_SECONDS 30
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
54struct dw_wdt {
55 void __iomem *regs;
56 struct clk *clk;
57 struct notifier_block restart_handler;
58 struct watchdog_device wdd;
59};
60
61#define to_dw_wdt(wdd) container_of(wdd, struct dw_wdt, wdd)
62
63static inline int dw_wdt_is_enabled(struct dw_wdt *dw_wdt)
64{
65 return readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET) &
66 WDOG_CONTROL_REG_WDT_EN_MASK;
67}
68
69static inline int dw_wdt_top_in_seconds(struct dw_wdt *dw_wdt, unsigned top)
70{
71 /*
72 * There are 16 possible timeout values in 0..15 where the number of
73 * cycles is 2 ^ (16 + i) and the watchdog counts down.
74 */
75 return (1U << (16 + top)) / clk_get_rate(dw_wdt->clk);
76}
77
78static int dw_wdt_get_top(struct dw_wdt *dw_wdt)
79{
80 int top = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
81
82 return dw_wdt_top_in_seconds(dw_wdt, top);
83}
84
85static int dw_wdt_ping(struct watchdog_device *wdd)
86{
87 struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
88
89 writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt->regs +
90 WDOG_COUNTER_RESTART_REG_OFFSET);
91
92 return 0;
93}
94
95static int dw_wdt_set_timeout(struct watchdog_device *wdd, unsigned int top_s)
96{
97 struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
98 int i, top_val = DW_WDT_MAX_TOP;
99
100 /*
101 * Iterate over the timeout values until we find the closest match. We
102 * always look for >=.
103 */
104 for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
105 if (dw_wdt_top_in_seconds(dw_wdt, i) >= top_s) {
106 top_val = i;
107 break;
108 }
109
110 /*
111 * Set the new value in the watchdog. Some versions of dw_wdt
112 * have have TOPINIT in the TIMEOUT_RANGE register (as per
113 * CP_WDT_DUAL_TOP in WDT_COMP_PARAMS_1). On those we
114 * effectively get a pat of the watchdog right here.
115 */
116 writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
117 dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
118
119 wdd->timeout = dw_wdt_top_in_seconds(dw_wdt, top_val);
120
121 return 0;
122}
123
124static int dw_wdt_start(struct watchdog_device *wdd)
125{
126 struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
127
128 dw_wdt_set_timeout(wdd, wdd->timeout);
129
130 set_bit(WDOG_HW_RUNNING, &wdd->status);
131
132 writel(WDOG_CONTROL_REG_WDT_EN_MASK,
133 dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
134
135 return 0;
136}
137
138static int dw_wdt_restart_handle(struct notifier_block *this,
139 unsigned long mode, void *cmd)
140{
141 struct dw_wdt *dw_wdt;
142 u32 val;
143
144 dw_wdt = container_of(this, struct dw_wdt, restart_handler);
145
146 writel(0, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
147 val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
148 if (val & WDOG_CONTROL_REG_WDT_EN_MASK)
149 writel(WDOG_COUNTER_RESTART_KICK_VALUE,
150 dw_wdt->regs + WDOG_COUNTER_RESTART_REG_OFFSET);
151 else
152 writel(WDOG_CONTROL_REG_WDT_EN_MASK,
153 dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
154
155 /* wait for reset to assert... */
156 mdelay(500);
157
158 return NOTIFY_DONE;
159}
160
161static unsigned int dw_wdt_get_timeleft(struct watchdog_device *wdd)
162{
163 struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
164
165 return readl(dw_wdt->regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
166 clk_get_rate(dw_wdt->clk);
167}
168
169static const struct watchdog_info dw_wdt_ident = {
170 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
171 WDIOF_MAGICCLOSE,
172 .identity = "Synopsys DesignWare Watchdog",
173};
174
175static const struct watchdog_ops dw_wdt_ops = {
176 .owner = THIS_MODULE,
177 .start = dw_wdt_start,
178 .ping = dw_wdt_ping,
179 .set_timeout = dw_wdt_set_timeout,
180 .get_timeleft = dw_wdt_get_timeleft,
181};
182
183#ifdef CONFIG_PM_SLEEP
184static int dw_wdt_suspend(struct device *dev)
185{
186 struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
187
188 clk_disable_unprepare(dw_wdt->clk);
189
190 return 0;
191}
192
193static int dw_wdt_resume(struct device *dev)
194{
195 struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
196 int err = clk_prepare_enable(dw_wdt->clk);
197
198 if (err)
199 return err;
200
201 dw_wdt_ping(&dw_wdt->wdd);
202
203 return 0;
204}
205#endif /* CONFIG_PM_SLEEP */
206
207static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
208
209static int dw_wdt_drv_probe(struct platform_device *pdev)
210{
211 struct device *dev = &pdev->dev;
212 struct watchdog_device *wdd;
213 struct dw_wdt *dw_wdt;
214 struct resource *mem;
215 int ret;
216
217 dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);
218 if (!dw_wdt)
219 return -ENOMEM;
220
221 mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
222 dw_wdt->regs = devm_ioremap_resource(dev, mem);
223 if (IS_ERR(dw_wdt->regs))
224 return PTR_ERR(dw_wdt->regs);
225
226 dw_wdt->clk = devm_clk_get(dev, NULL);
227 if (IS_ERR(dw_wdt->clk))
228 return PTR_ERR(dw_wdt->clk);
229
230 ret = clk_prepare_enable(dw_wdt->clk);
231 if (ret)
232 return ret;
233
234 wdd = &dw_wdt->wdd;
235 wdd->info = &dw_wdt_ident;
236 wdd->ops = &dw_wdt_ops;
237 wdd->min_timeout = 1;
238 wdd->max_hw_heartbeat_ms =
239 dw_wdt_top_in_seconds(dw_wdt, DW_WDT_MAX_TOP) * 1000;
240 wdd->parent = dev;
241
242 watchdog_set_drvdata(wdd, dw_wdt);
243 watchdog_set_nowayout(wdd, nowayout);
244 watchdog_init_timeout(wdd, 0, dev);
245
246 /*
247 * If the watchdog is already running, use its already configured
248 * timeout. Otherwise use the default or the value provided through
249 * devicetree.
250 */
251 if (dw_wdt_is_enabled(dw_wdt)) {
252 wdd->timeout = dw_wdt_get_top(dw_wdt);
253 set_bit(WDOG_HW_RUNNING, &wdd->status);
254 } else {
255 wdd->timeout = DW_WDT_DEFAULT_SECONDS;
256 watchdog_init_timeout(wdd, 0, dev);
257 }
258
259 platform_set_drvdata(pdev, dw_wdt);
260
261 ret = watchdog_register_device(wdd);
262 if (ret)
263 goto out_disable_clk;
264
265 dw_wdt->restart_handler.notifier_call = dw_wdt_restart_handle;
266 dw_wdt->restart_handler.priority = 128;
267 ret = register_restart_handler(&dw_wdt->restart_handler);
268 if (ret)
269 pr_warn("cannot register restart handler\n");
270
271 return 0;
272
273out_disable_clk:
274 clk_disable_unprepare(dw_wdt->clk);
275 return ret;
276}
277
278static int dw_wdt_drv_remove(struct platform_device *pdev)
279{
280 struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);
281
282 unregister_restart_handler(&dw_wdt->restart_handler);
283 watchdog_unregister_device(&dw_wdt->wdd);
284 clk_disable_unprepare(dw_wdt->clk);
285
286 return 0;
287}
288
289#ifdef CONFIG_OF
290static const struct of_device_id dw_wdt_of_match[] = {
291 { .compatible = "snps,dw-wdt", },
292 { /* sentinel */ }
293};
294MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
295#endif
296
297static struct platform_driver dw_wdt_driver = {
298 .probe = dw_wdt_drv_probe,
299 .remove = dw_wdt_drv_remove,
300 .driver = {
301 .name = "dw_wdt",
302 .of_match_table = of_match_ptr(dw_wdt_of_match),
303 .pm = &dw_wdt_pm_ops,
304 },
305};
306
307module_platform_driver(dw_wdt_driver);
308
309MODULE_AUTHOR("Jamie Iles");
310MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
311MODULE_LICENSE("GPL");