2 * drivers/char/watchdog/sp805-wdt.c
4 * Watchdog driver for ARM SP805 watchdog module
6 * Copyright (C) 2010 ST Microelectronics
7 * Viresh Kumar <viresh.linux@gmail.com>
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.
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>
20 #include <linux/ioport.h>
21 #include <linux/kernel.h>
22 #include <linux/math64.h>
23 #include <linux/module.h>
24 #include <linux/moduleparam.h>
26 #include <linux/slab.h>
27 #include <linux/spinlock.h>
28 #include <linux/types.h>
29 #include <linux/watchdog.h>
31 /* default timeout in seconds */
32 #define DEFAULT_TIMEOUT 60
34 #define MODULE_NAME "sp805-wdt"
36 /* watchdog register offsets and masks */
38 #define LOAD_MIN 0x00000001
39 #define LOAD_MAX 0xFFFFFFFF
40 #define WDTVALUE 0x004
41 #define WDTCONTROL 0x008
42 /* control register masks */
43 #define INT_ENABLE (1 << 0)
44 #define RESET_ENABLE (1 << 1)
45 #define WDTINTCLR 0x00C
48 #define INT_MASK (1 << 0)
50 #define UNLOCK 0x1ACCE551
51 #define LOCK 0x00000001
54 * struct sp805_wdt: sp805 wdt device structure
55 * @wdd: instance of struct watchdog_device
56 * @lock: spin lock protecting dev structure and io access
57 * @base: base address of wdt
58 * @clk: clock structure of wdt
59 * @adev: amba device structure of wdt
60 * @status: current status of wdt
61 * @load_val: load value to be set for current timeout
64 struct watchdog_device wdd
;
68 struct amba_device
*adev
;
69 unsigned int load_val
;
72 static bool nowayout
= WATCHDOG_NOWAYOUT
;
73 module_param(nowayout
, bool, 0);
74 MODULE_PARM_DESC(nowayout
,
75 "Set to 1 to keep watchdog running after device release");
77 /* This routine finds load value that will reset system in required timout */
78 static int wdt_setload(struct watchdog_device
*wdd
, unsigned int timeout
)
80 struct sp805_wdt
*wdt
= watchdog_get_drvdata(wdd
);
83 rate
= clk_get_rate(wdt
->clk
);
86 * sp805 runs counter with given value twice, after the end of first
87 * counter it gives an interrupt and then starts counter again. If
88 * interrupt already occurred then it resets the system. This is why
89 * load is half of what should be required.
91 load
= div_u64(rate
, 2) * timeout
- 1;
93 load
= (load
> LOAD_MAX
) ? LOAD_MAX
: load
;
94 load
= (load
< LOAD_MIN
) ? LOAD_MIN
: load
;
96 spin_lock(&wdt
->lock
);
98 /* roundup timeout to closest positive integer value */
99 wdd
->timeout
= div_u64((load
+ 1) * 2 + (rate
/ 2), rate
);
100 spin_unlock(&wdt
->lock
);
105 /* returns number of seconds left for reset to occur */
106 static unsigned int wdt_timeleft(struct watchdog_device
*wdd
)
108 struct sp805_wdt
*wdt
= watchdog_get_drvdata(wdd
);
111 rate
= clk_get_rate(wdt
->clk
);
113 spin_lock(&wdt
->lock
);
114 load
= readl_relaxed(wdt
->base
+ WDTVALUE
);
116 /*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
117 if (!(readl_relaxed(wdt
->base
+ WDTRIS
) & INT_MASK
))
118 load
+= wdt
->load_val
+ 1;
119 spin_unlock(&wdt
->lock
);
121 return div_u64(load
, rate
);
124 static int wdt_config(struct watchdog_device
*wdd
, bool ping
)
126 struct sp805_wdt
*wdt
= watchdog_get_drvdata(wdd
);
131 ret
= clk_prepare_enable(wdt
->clk
);
133 dev_err(&wdt
->adev
->dev
, "clock enable fail");
138 spin_lock(&wdt
->lock
);
140 writel_relaxed(UNLOCK
, wdt
->base
+ WDTLOCK
);
141 writel_relaxed(wdt
->load_val
, wdt
->base
+ WDTLOAD
);
144 writel_relaxed(INT_MASK
, wdt
->base
+ WDTINTCLR
);
145 writel_relaxed(INT_ENABLE
| RESET_ENABLE
, wdt
->base
+
149 writel_relaxed(LOCK
, wdt
->base
+ WDTLOCK
);
151 /* Flush posted writes. */
152 readl_relaxed(wdt
->base
+ WDTLOCK
);
153 spin_unlock(&wdt
->lock
);
158 static int wdt_ping(struct watchdog_device
*wdd
)
160 return wdt_config(wdd
, true);
163 /* enables watchdog timers reset */
164 static int wdt_enable(struct watchdog_device
*wdd
)
166 return wdt_config(wdd
, false);
169 /* disables watchdog timers reset */
170 static int wdt_disable(struct watchdog_device
*wdd
)
172 struct sp805_wdt
*wdt
= watchdog_get_drvdata(wdd
);
174 spin_lock(&wdt
->lock
);
176 writel_relaxed(UNLOCK
, wdt
->base
+ WDTLOCK
);
177 writel_relaxed(0, wdt
->base
+ WDTCONTROL
);
178 writel_relaxed(LOCK
, wdt
->base
+ WDTLOCK
);
180 /* Flush posted writes. */
181 readl_relaxed(wdt
->base
+ WDTLOCK
);
182 spin_unlock(&wdt
->lock
);
184 clk_disable_unprepare(wdt
->clk
);
189 static const struct watchdog_info wdt_info
= {
190 .options
= WDIOF_MAGICCLOSE
| WDIOF_SETTIMEOUT
| WDIOF_KEEPALIVEPING
,
191 .identity
= MODULE_NAME
,
194 static const struct watchdog_ops wdt_ops
= {
195 .owner
= THIS_MODULE
,
199 .set_timeout
= wdt_setload
,
200 .get_timeleft
= wdt_timeleft
,
204 sp805_wdt_probe(struct amba_device
*adev
, const struct amba_id
*id
)
206 struct sp805_wdt
*wdt
;
209 wdt
= devm_kzalloc(&adev
->dev
, sizeof(*wdt
), GFP_KERNEL
);
215 wdt
->base
= devm_ioremap_resource(&adev
->dev
, &adev
->res
);
216 if (IS_ERR(wdt
->base
))
217 return PTR_ERR(wdt
->base
);
219 wdt
->clk
= devm_clk_get(&adev
->dev
, NULL
);
220 if (IS_ERR(wdt
->clk
)) {
221 dev_warn(&adev
->dev
, "Clock not found\n");
222 ret
= PTR_ERR(wdt
->clk
);
227 wdt
->wdd
.info
= &wdt_info
;
228 wdt
->wdd
.ops
= &wdt_ops
;
230 spin_lock_init(&wdt
->lock
);
231 watchdog_set_nowayout(&wdt
->wdd
, nowayout
);
232 watchdog_set_drvdata(&wdt
->wdd
, wdt
);
233 wdt_setload(&wdt
->wdd
, DEFAULT_TIMEOUT
);
235 ret
= watchdog_register_device(&wdt
->wdd
);
237 dev_err(&adev
->dev
, "watchdog_register_device() failed: %d\n",
241 amba_set_drvdata(adev
, wdt
);
243 dev_info(&adev
->dev
, "registration successful\n");
247 dev_err(&adev
->dev
, "Probe Failed!!!\n");
251 static int sp805_wdt_remove(struct amba_device
*adev
)
253 struct sp805_wdt
*wdt
= amba_get_drvdata(adev
);
255 watchdog_unregister_device(&wdt
->wdd
);
256 watchdog_set_drvdata(&wdt
->wdd
, NULL
);
261 static int __maybe_unused
sp805_wdt_suspend(struct device
*dev
)
263 struct sp805_wdt
*wdt
= dev_get_drvdata(dev
);
265 if (watchdog_active(&wdt
->wdd
))
266 return wdt_disable(&wdt
->wdd
);
271 static int __maybe_unused
sp805_wdt_resume(struct device
*dev
)
273 struct sp805_wdt
*wdt
= dev_get_drvdata(dev
);
275 if (watchdog_active(&wdt
->wdd
))
276 return wdt_enable(&wdt
->wdd
);
281 static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops
, sp805_wdt_suspend
,
284 static struct amba_id sp805_wdt_ids
[] = {
292 MODULE_DEVICE_TABLE(amba
, sp805_wdt_ids
);
294 static struct amba_driver sp805_wdt_driver
= {
297 .pm
= &sp805_wdt_dev_pm_ops
,
299 .id_table
= sp805_wdt_ids
,
300 .probe
= sp805_wdt_probe
,
301 .remove
= sp805_wdt_remove
,
304 module_amba_driver(sp805_wdt_driver
);
306 MODULE_AUTHOR("Viresh Kumar <viresh.linux@gmail.com>");
307 MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
308 MODULE_LICENSE("GPL");