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[karo-tx-linux.git] / drivers / watchdog / sp805_wdt.c
1 /*
2  * drivers/char/watchdog/sp805-wdt.c
3  *
4  * Watchdog driver for ARM SP805 watchdog module
5  *
6  * Copyright (C) 2010 ST Microelectronics
7  * Viresh Kumar <viresh.linux@gmail.com>
8  *
9  * This file is licensed under the terms of the GNU General Public
10  * License version 2 or later. This program is licensed "as is" without any
11  * warranty of any kind, whether express or implied.
12  */
13
14 #include <linux/device.h>
15 #include <linux/resource.h>
16 #include <linux/amba/bus.h>
17 #include <linux/bitops.h>
18 #include <linux/clk.h>
19 #include <linux/init.h>
20 #include <linux/io.h>
21 #include <linux/ioport.h>
22 #include <linux/kernel.h>
23 #include <linux/math64.h>
24 #include <linux/module.h>
25 #include <linux/moduleparam.h>
26 #include <linux/pm.h>
27 #include <linux/slab.h>
28 #include <linux/spinlock.h>
29 #include <linux/types.h>
30 #include <linux/watchdog.h>
31
32 /* default timeout in seconds */
33 #define DEFAULT_TIMEOUT         60
34
35 #define MODULE_NAME             "sp805-wdt"
36
37 /* watchdog register offsets and masks */
38 #define WDTLOAD                 0x000
39         #define LOAD_MIN        0x00000001
40         #define LOAD_MAX        0xFFFFFFFF
41 #define WDTVALUE                0x004
42 #define WDTCONTROL              0x008
43         /* control register masks */
44         #define INT_ENABLE      (1 << 0)
45         #define RESET_ENABLE    (1 << 1)
46 #define WDTINTCLR               0x00C
47 #define WDTRIS                  0x010
48 #define WDTMIS                  0x014
49         #define INT_MASK        (1 << 0)
50 #define WDTLOCK                 0xC00
51         #define UNLOCK          0x1ACCE551
52         #define LOCK            0x00000001
53
54 /**
55  * struct sp805_wdt: sp805 wdt device structure
56  * @wdd: instance of struct watchdog_device
57  * @lock: spin lock protecting dev structure and io access
58  * @base: base address of wdt
59  * @clk: clock structure of wdt
60  * @adev: amba device structure of wdt
61  * @status: current status of wdt
62  * @load_val: load value to be set for current timeout
63  * @timeout: current programmed timeout
64  */
65 struct sp805_wdt {
66         struct watchdog_device          wdd;
67         spinlock_t                      lock;
68         void __iomem                    *base;
69         struct clk                      *clk;
70         struct amba_device              *adev;
71         unsigned int                    load_val;
72         unsigned int                    timeout;
73 };
74
75 static bool nowayout = WATCHDOG_NOWAYOUT;
76 module_param(nowayout, bool, 0);
77 MODULE_PARM_DESC(nowayout,
78                 "Set to 1 to keep watchdog running after device release");
79
80 /* This routine finds load value that will reset system in required timout */
81 static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
82 {
83         struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
84         u64 load, rate;
85
86         rate = clk_get_rate(wdt->clk);
87
88         /*
89          * sp805 runs counter with given value twice, after the end of first
90          * counter it gives an interrupt and then starts counter again. If
91          * interrupt already occurred then it resets the system. This is why
92          * load is half of what should be required.
93          */
94         load = div_u64(rate, 2) * timeout - 1;
95
96         load = (load > LOAD_MAX) ? LOAD_MAX : load;
97         load = (load < LOAD_MIN) ? LOAD_MIN : load;
98
99         spin_lock(&wdt->lock);
100         wdt->load_val = load;
101         /* roundup timeout to closest positive integer value */
102         wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
103         spin_unlock(&wdt->lock);
104
105         return 0;
106 }
107
108 /* returns number of seconds left for reset to occur */
109 static unsigned int wdt_timeleft(struct watchdog_device *wdd)
110 {
111         struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
112         u64 load, rate;
113
114         rate = clk_get_rate(wdt->clk);
115
116         spin_lock(&wdt->lock);
117         load = readl_relaxed(wdt->base + WDTVALUE);
118
119         /*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
120         if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK))
121                 load += wdt->load_val + 1;
122         spin_unlock(&wdt->lock);
123
124         return div_u64(load, rate);
125 }
126
127 static int wdt_config(struct watchdog_device *wdd, bool ping)
128 {
129         struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
130         int ret;
131
132         if (!ping) {
133
134                 ret = clk_prepare_enable(wdt->clk);
135                 if (ret) {
136                         dev_err(&wdt->adev->dev, "clock enable fail");
137                         return ret;
138                 }
139         }
140
141         spin_lock(&wdt->lock);
142
143         writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
144         writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
145
146         if (!ping) {
147                 writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
148                 writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
149                                 WDTCONTROL);
150         }
151
152         writel_relaxed(LOCK, wdt->base + WDTLOCK);
153
154         /* Flush posted writes. */
155         readl_relaxed(wdt->base + WDTLOCK);
156         spin_unlock(&wdt->lock);
157
158         return 0;
159 }
160
161 static int wdt_ping(struct watchdog_device *wdd)
162 {
163         return wdt_config(wdd, true);
164 }
165
166 /* enables watchdog timers reset */
167 static int wdt_enable(struct watchdog_device *wdd)
168 {
169         return wdt_config(wdd, false);
170 }
171
172 /* disables watchdog timers reset */
173 static int wdt_disable(struct watchdog_device *wdd)
174 {
175         struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
176
177         spin_lock(&wdt->lock);
178
179         writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
180         writel_relaxed(0, wdt->base + WDTCONTROL);
181         writel_relaxed(LOCK, wdt->base + WDTLOCK);
182
183         /* Flush posted writes. */
184         readl_relaxed(wdt->base + WDTLOCK);
185         spin_unlock(&wdt->lock);
186
187         clk_disable_unprepare(wdt->clk);
188
189         return 0;
190 }
191
192 static const struct watchdog_info wdt_info = {
193         .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
194         .identity = MODULE_NAME,
195 };
196
197 static const struct watchdog_ops wdt_ops = {
198         .owner          = THIS_MODULE,
199         .start          = wdt_enable,
200         .stop           = wdt_disable,
201         .ping           = wdt_ping,
202         .set_timeout    = wdt_setload,
203         .get_timeleft   = wdt_timeleft,
204 };
205
206 static int
207 sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
208 {
209         struct sp805_wdt *wdt;
210         int ret = 0;
211
212         if (!devm_request_mem_region(&adev->dev, adev->res.start,
213                                 resource_size(&adev->res), "sp805_wdt")) {
214                 dev_warn(&adev->dev, "Failed to get memory region resource\n");
215                 ret = -ENOENT;
216                 goto err;
217         }
218
219         wdt = devm_kzalloc(&adev->dev, sizeof(*wdt), GFP_KERNEL);
220         if (!wdt) {
221                 dev_warn(&adev->dev, "Kzalloc failed\n");
222                 ret = -ENOMEM;
223                 goto err;
224         }
225
226         wdt->base = devm_ioremap(&adev->dev, adev->res.start,
227                         resource_size(&adev->res));
228         if (!wdt->base) {
229                 ret = -ENOMEM;
230                 dev_warn(&adev->dev, "ioremap fail\n");
231                 goto err;
232         }
233
234         wdt->clk = clk_get(&adev->dev, NULL);
235         if (IS_ERR(wdt->clk)) {
236                 dev_warn(&adev->dev, "Clock not found\n");
237                 ret = PTR_ERR(wdt->clk);
238                 goto err;
239         }
240
241         wdt->adev = adev;
242         wdt->wdd.info = &wdt_info;
243         wdt->wdd.ops = &wdt_ops;
244
245         spin_lock_init(&wdt->lock);
246         watchdog_set_nowayout(&wdt->wdd, nowayout);
247         watchdog_set_drvdata(&wdt->wdd, wdt);
248         wdt_setload(&wdt->wdd, DEFAULT_TIMEOUT);
249
250         ret = watchdog_register_device(&wdt->wdd);
251         if (ret) {
252                 dev_err(&adev->dev, "watchdog_register_device() failed: %d\n",
253                                 ret);
254                 goto err_register;
255         }
256         amba_set_drvdata(adev, wdt);
257
258         dev_info(&adev->dev, "registration successful\n");
259         return 0;
260
261 err_register:
262         clk_put(wdt->clk);
263 err:
264         dev_err(&adev->dev, "Probe Failed!!!\n");
265         return ret;
266 }
267
268 static int sp805_wdt_remove(struct amba_device *adev)
269 {
270         struct sp805_wdt *wdt = amba_get_drvdata(adev);
271
272         watchdog_unregister_device(&wdt->wdd);
273         amba_set_drvdata(adev, NULL);
274         watchdog_set_drvdata(&wdt->wdd, NULL);
275         clk_put(wdt->clk);
276
277         return 0;
278 }
279
280 static int __maybe_unused sp805_wdt_suspend(struct device *dev)
281 {
282         struct sp805_wdt *wdt = dev_get_drvdata(dev);
283
284         if (watchdog_active(&wdt->wdd))
285                 return wdt_disable(&wdt->wdd);
286
287         return 0;
288 }
289
290 static int __maybe_unused sp805_wdt_resume(struct device *dev)
291 {
292         struct sp805_wdt *wdt = dev_get_drvdata(dev);
293
294         if (watchdog_active(&wdt->wdd))
295                 return wdt_enable(&wdt->wdd);
296
297         return 0;
298 }
299
300 static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend,
301                 sp805_wdt_resume);
302
303 static struct amba_id sp805_wdt_ids[] = {
304         {
305                 .id     = 0x00141805,
306                 .mask   = 0x00ffffff,
307         },
308         { 0, 0 },
309 };
310
311 MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);
312
313 static struct amba_driver sp805_wdt_driver = {
314         .drv = {
315                 .name   = MODULE_NAME,
316                 .pm     = &sp805_wdt_dev_pm_ops,
317         },
318         .id_table       = sp805_wdt_ids,
319         .probe          = sp805_wdt_probe,
320         .remove = sp805_wdt_remove,
321 };
322
323 module_amba_driver(sp805_wdt_driver);
324
325 MODULE_AUTHOR("Viresh Kumar <viresh.linux@gmail.com>");
326 MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
327 MODULE_LICENSE("GPL");