2 * Copyright 2010-2011 Picochip Ltd., Jamie Iles
3 * http://www.picochip.com
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.
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.
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.
19 #include <linux/bitops.h>
20 #include <linux/clk.h>
21 #include <linux/delay.h>
22 #include <linux/err.h>
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/moduleparam.h>
29 #include <linux/platform_device.h>
30 #include <linux/reset.h>
31 #include <linux/watchdog.h>
33 #define WDOG_CONTROL_REG_OFFSET 0x00
34 #define WDOG_CONTROL_REG_WDT_EN_MASK 0x01
35 #define WDOG_CONTROL_REG_RESP_MODE_MASK 0x02
36 #define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04
37 #define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT 4
38 #define WDOG_CURRENT_COUNT_REG_OFFSET 0x08
39 #define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c
40 #define WDOG_COUNTER_RESTART_KICK_VALUE 0x76
42 /* The maximum TOP (timeout period) value that can be set in the watchdog. */
43 #define DW_WDT_MAX_TOP 15
45 #define DW_WDT_DEFAULT_SECONDS 30
47 static bool nowayout
= WATCHDOG_NOWAYOUT
;
48 module_param(nowayout
, bool, 0);
49 MODULE_PARM_DESC(nowayout
, "Watchdog cannot be stopped once started "
50 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT
) ")");
56 struct watchdog_device wdd
;
57 struct reset_control
*rst
;
63 #define to_dw_wdt(wdd) container_of(wdd, struct dw_wdt, wdd)
65 static inline int dw_wdt_is_enabled(struct dw_wdt
*dw_wdt
)
67 return readl(dw_wdt
->regs
+ WDOG_CONTROL_REG_OFFSET
) &
68 WDOG_CONTROL_REG_WDT_EN_MASK
;
71 static inline int dw_wdt_top_in_seconds(struct dw_wdt
*dw_wdt
, unsigned top
)
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.
77 return (1U << (16 + top
)) / dw_wdt
->rate
;
80 static int dw_wdt_get_top(struct dw_wdt
*dw_wdt
)
82 int top
= readl(dw_wdt
->regs
+ WDOG_TIMEOUT_RANGE_REG_OFFSET
) & 0xF;
84 return dw_wdt_top_in_seconds(dw_wdt
, top
);
87 static int dw_wdt_ping(struct watchdog_device
*wdd
)
89 struct dw_wdt
*dw_wdt
= to_dw_wdt(wdd
);
91 writel(WDOG_COUNTER_RESTART_KICK_VALUE
, dw_wdt
->regs
+
92 WDOG_COUNTER_RESTART_REG_OFFSET
);
97 static int dw_wdt_set_timeout(struct watchdog_device
*wdd
, unsigned int top_s
)
99 struct dw_wdt
*dw_wdt
= to_dw_wdt(wdd
);
100 int i
, top_val
= DW_WDT_MAX_TOP
;
103 * Iterate over the timeout values until we find the closest match. We
104 * always look for >=.
106 for (i
= 0; i
<= DW_WDT_MAX_TOP
; ++i
)
107 if (dw_wdt_top_in_seconds(dw_wdt
, i
) >= top_s
) {
113 * Set the new value in the watchdog. Some versions of dw_wdt
114 * have have TOPINIT in the TIMEOUT_RANGE register (as per
115 * CP_WDT_DUAL_TOP in WDT_COMP_PARAMS_1). On those we
116 * effectively get a pat of the watchdog right here.
118 writel(top_val
| top_val
<< WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT
,
119 dw_wdt
->regs
+ WDOG_TIMEOUT_RANGE_REG_OFFSET
);
121 wdd
->timeout
= dw_wdt_top_in_seconds(dw_wdt
, top_val
);
126 static void dw_wdt_arm_system_reset(struct dw_wdt
*dw_wdt
)
128 u32 val
= readl(dw_wdt
->regs
+ WDOG_CONTROL_REG_OFFSET
);
130 /* Disable interrupt mode; always perform system reset. */
131 val
&= ~WDOG_CONTROL_REG_RESP_MODE_MASK
;
132 /* Enable watchdog. */
133 val
|= WDOG_CONTROL_REG_WDT_EN_MASK
;
134 writel(val
, dw_wdt
->regs
+ WDOG_CONTROL_REG_OFFSET
);
137 static int dw_wdt_start(struct watchdog_device
*wdd
)
139 struct dw_wdt
*dw_wdt
= to_dw_wdt(wdd
);
141 dw_wdt_set_timeout(wdd
, wdd
->timeout
);
142 dw_wdt_arm_system_reset(dw_wdt
);
147 static int dw_wdt_stop(struct watchdog_device
*wdd
)
149 struct dw_wdt
*dw_wdt
= to_dw_wdt(wdd
);
152 set_bit(WDOG_HW_RUNNING
, &wdd
->status
);
156 reset_control_assert(dw_wdt
->rst
);
157 reset_control_deassert(dw_wdt
->rst
);
162 static int dw_wdt_restart(struct watchdog_device
*wdd
,
163 unsigned long action
, void *data
)
165 struct dw_wdt
*dw_wdt
= to_dw_wdt(wdd
);
167 writel(0, dw_wdt
->regs
+ WDOG_TIMEOUT_RANGE_REG_OFFSET
);
168 if (dw_wdt_is_enabled(dw_wdt
))
169 writel(WDOG_COUNTER_RESTART_KICK_VALUE
,
170 dw_wdt
->regs
+ WDOG_COUNTER_RESTART_REG_OFFSET
);
172 dw_wdt_arm_system_reset(dw_wdt
);
174 /* wait for reset to assert... */
180 static unsigned int dw_wdt_get_timeleft(struct watchdog_device
*wdd
)
182 struct dw_wdt
*dw_wdt
= to_dw_wdt(wdd
);
184 return readl(dw_wdt
->regs
+ WDOG_CURRENT_COUNT_REG_OFFSET
) /
188 static const struct watchdog_info dw_wdt_ident
= {
189 .options
= WDIOF_KEEPALIVEPING
| WDIOF_SETTIMEOUT
|
191 .identity
= "Synopsys DesignWare Watchdog",
194 static const struct watchdog_ops dw_wdt_ops
= {
195 .owner
= THIS_MODULE
,
196 .start
= dw_wdt_start
,
199 .set_timeout
= dw_wdt_set_timeout
,
200 .get_timeleft
= dw_wdt_get_timeleft
,
201 .restart
= dw_wdt_restart
,
204 #ifdef CONFIG_PM_SLEEP
205 static int dw_wdt_suspend(struct device
*dev
)
207 struct dw_wdt
*dw_wdt
= dev_get_drvdata(dev
);
209 dw_wdt
->control
= readl(dw_wdt
->regs
+ WDOG_CONTROL_REG_OFFSET
);
210 dw_wdt
->timeout
= readl(dw_wdt
->regs
+ WDOG_TIMEOUT_RANGE_REG_OFFSET
);
212 clk_disable_unprepare(dw_wdt
->clk
);
217 static int dw_wdt_resume(struct device
*dev
)
219 struct dw_wdt
*dw_wdt
= dev_get_drvdata(dev
);
220 int err
= clk_prepare_enable(dw_wdt
->clk
);
225 writel(dw_wdt
->timeout
, dw_wdt
->regs
+ WDOG_TIMEOUT_RANGE_REG_OFFSET
);
226 writel(dw_wdt
->control
, dw_wdt
->regs
+ WDOG_CONTROL_REG_OFFSET
);
228 dw_wdt_ping(&dw_wdt
->wdd
);
232 #endif /* CONFIG_PM_SLEEP */
234 static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops
, dw_wdt_suspend
, dw_wdt_resume
);
236 static int dw_wdt_drv_probe(struct platform_device
*pdev
)
238 struct device
*dev
= &pdev
->dev
;
239 struct watchdog_device
*wdd
;
240 struct dw_wdt
*dw_wdt
;
243 dw_wdt
= devm_kzalloc(dev
, sizeof(*dw_wdt
), GFP_KERNEL
);
247 dw_wdt
->regs
= devm_platform_ioremap_resource(pdev
, 0);
248 if (IS_ERR(dw_wdt
->regs
))
249 return PTR_ERR(dw_wdt
->regs
);
251 dw_wdt
->clk
= devm_clk_get(dev
, NULL
);
252 if (IS_ERR(dw_wdt
->clk
))
253 return PTR_ERR(dw_wdt
->clk
);
255 ret
= clk_prepare_enable(dw_wdt
->clk
);
259 dw_wdt
->rate
= clk_get_rate(dw_wdt
->clk
);
260 if (dw_wdt
->rate
== 0) {
262 goto out_disable_clk
;
265 dw_wdt
->rst
= devm_reset_control_get_optional_shared(&pdev
->dev
, NULL
);
266 if (IS_ERR(dw_wdt
->rst
)) {
267 ret
= PTR_ERR(dw_wdt
->rst
);
268 goto out_disable_clk
;
271 reset_control_deassert(dw_wdt
->rst
);
274 wdd
->info
= &dw_wdt_ident
;
275 wdd
->ops
= &dw_wdt_ops
;
276 wdd
->min_timeout
= 1;
277 wdd
->max_hw_heartbeat_ms
=
278 dw_wdt_top_in_seconds(dw_wdt
, DW_WDT_MAX_TOP
) * 1000;
281 watchdog_set_drvdata(wdd
, dw_wdt
);
282 watchdog_set_nowayout(wdd
, nowayout
);
283 watchdog_init_timeout(wdd
, 0, dev
);
286 * If the watchdog is already running, use its already configured
287 * timeout. Otherwise use the default or the value provided through
290 if (dw_wdt_is_enabled(dw_wdt
)) {
291 wdd
->timeout
= dw_wdt_get_top(dw_wdt
);
292 set_bit(WDOG_HW_RUNNING
, &wdd
->status
);
294 wdd
->timeout
= DW_WDT_DEFAULT_SECONDS
;
295 watchdog_init_timeout(wdd
, 0, dev
);
298 platform_set_drvdata(pdev
, dw_wdt
);
300 watchdog_set_restart_priority(wdd
, 128);
302 ret
= watchdog_register_device(wdd
);
304 goto out_disable_clk
;
309 clk_disable_unprepare(dw_wdt
->clk
);
313 static int dw_wdt_drv_remove(struct platform_device
*pdev
)
315 struct dw_wdt
*dw_wdt
= platform_get_drvdata(pdev
);
317 watchdog_unregister_device(&dw_wdt
->wdd
);
318 reset_control_assert(dw_wdt
->rst
);
319 clk_disable_unprepare(dw_wdt
->clk
);
325 static const struct of_device_id dw_wdt_of_match
[] = {
326 { .compatible
= "snps,dw-wdt", },
329 MODULE_DEVICE_TABLE(of
, dw_wdt_of_match
);
332 static struct platform_driver dw_wdt_driver
= {
333 .probe
= dw_wdt_drv_probe
,
334 .remove
= dw_wdt_drv_remove
,
337 .of_match_table
= of_match_ptr(dw_wdt_of_match
),
338 .pm
= &dw_wdt_pm_ops
,
342 module_platform_driver(dw_wdt_driver
);
344 MODULE_AUTHOR("Jamie Iles");
345 MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
346 MODULE_LICENSE("GPL");