2 * NXP LPC18xx Watchdog Timer (WDT)
4 * Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com>
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published by
8 * the Free Software Foundation.
12 * The Watchdog consists of a fixed divide-by-4 clock pre-scaler and a 24-bit
13 * counter which decrements on every clock cycle.
16 #include <linux/clk.h>
18 #include <linux/module.h>
20 #include <linux/platform_device.h>
21 #include <linux/watchdog.h>
24 #define LPC18XX_WDT_MOD 0x00
25 #define LPC18XX_WDT_MOD_WDEN BIT(0)
26 #define LPC18XX_WDT_MOD_WDRESET BIT(1)
28 #define LPC18XX_WDT_TC 0x04
29 #define LPC18XX_WDT_TC_MIN 0xff
30 #define LPC18XX_WDT_TC_MAX 0xffffff
32 #define LPC18XX_WDT_FEED 0x08
33 #define LPC18XX_WDT_FEED_MAGIC1 0xaa
34 #define LPC18XX_WDT_FEED_MAGIC2 0x55
36 #define LPC18XX_WDT_TV 0x0c
38 /* Clock pre-scaler */
39 #define LPC18XX_WDT_CLK_DIV 4
41 /* Timeout values in seconds */
42 #define LPC18XX_WDT_DEF_TIMEOUT 30U
45 module_param(heartbeat
, int, 0);
46 MODULE_PARM_DESC(heartbeat
, "Watchdog heartbeats in seconds (default="
47 __MODULE_STRING(LPC18XX_WDT_DEF_TIMEOUT
) ")");
49 static bool nowayout
= WATCHDOG_NOWAYOUT
;
50 module_param(nowayout
, bool, 0);
51 MODULE_PARM_DESC(nowayout
, "Watchdog cannot be stopped once started (default="
52 __MODULE_STRING(WATCHDOG_NOWAYOUT
) ")");
54 struct lpc18xx_wdt_dev
{
55 struct watchdog_device wdt_dev
;
58 unsigned long clk_rate
;
60 struct timer_list timer
;
64 static int lpc18xx_wdt_feed(struct watchdog_device
*wdt_dev
)
66 struct lpc18xx_wdt_dev
*lpc18xx_wdt
= watchdog_get_drvdata(wdt_dev
);
70 * An abort condition will occur if an interrupt happens during the feed
73 spin_lock_irqsave(&lpc18xx_wdt
->lock
, flags
);
74 writel(LPC18XX_WDT_FEED_MAGIC1
, lpc18xx_wdt
->base
+ LPC18XX_WDT_FEED
);
75 writel(LPC18XX_WDT_FEED_MAGIC2
, lpc18xx_wdt
->base
+ LPC18XX_WDT_FEED
);
76 spin_unlock_irqrestore(&lpc18xx_wdt
->lock
, flags
);
81 static void lpc18xx_wdt_timer_feed(unsigned long data
)
83 struct watchdog_device
*wdt_dev
= (struct watchdog_device
*)data
;
84 struct lpc18xx_wdt_dev
*lpc18xx_wdt
= watchdog_get_drvdata(wdt_dev
);
86 lpc18xx_wdt_feed(wdt_dev
);
88 /* Use safe value (1/2 of real timeout) */
89 mod_timer(&lpc18xx_wdt
->timer
, jiffies
+
90 msecs_to_jiffies((wdt_dev
->timeout
* MSEC_PER_SEC
) / 2));
94 * Since LPC18xx Watchdog cannot be disabled in hardware, we must keep feeding
95 * it with a timer until userspace watchdog software takes over.
97 static int lpc18xx_wdt_stop(struct watchdog_device
*wdt_dev
)
99 lpc18xx_wdt_timer_feed((unsigned long)wdt_dev
);
104 static void __lpc18xx_wdt_set_timeout(struct lpc18xx_wdt_dev
*lpc18xx_wdt
)
108 val
= DIV_ROUND_UP(lpc18xx_wdt
->wdt_dev
.timeout
* lpc18xx_wdt
->clk_rate
,
109 LPC18XX_WDT_CLK_DIV
);
110 writel(val
, lpc18xx_wdt
->base
+ LPC18XX_WDT_TC
);
113 static int lpc18xx_wdt_set_timeout(struct watchdog_device
*wdt_dev
,
114 unsigned int new_timeout
)
116 struct lpc18xx_wdt_dev
*lpc18xx_wdt
= watchdog_get_drvdata(wdt_dev
);
118 lpc18xx_wdt
->wdt_dev
.timeout
= new_timeout
;
119 __lpc18xx_wdt_set_timeout(lpc18xx_wdt
);
124 static unsigned int lpc18xx_wdt_get_timeleft(struct watchdog_device
*wdt_dev
)
126 struct lpc18xx_wdt_dev
*lpc18xx_wdt
= watchdog_get_drvdata(wdt_dev
);
129 val
= readl(lpc18xx_wdt
->base
+ LPC18XX_WDT_TV
);
130 return (val
* LPC18XX_WDT_CLK_DIV
) / lpc18xx_wdt
->clk_rate
;
133 static int lpc18xx_wdt_start(struct watchdog_device
*wdt_dev
)
135 struct lpc18xx_wdt_dev
*lpc18xx_wdt
= watchdog_get_drvdata(wdt_dev
);
138 if (timer_pending(&lpc18xx_wdt
->timer
))
139 del_timer(&lpc18xx_wdt
->timer
);
141 val
= readl(lpc18xx_wdt
->base
+ LPC18XX_WDT_MOD
);
142 val
|= LPC18XX_WDT_MOD_WDEN
;
143 val
|= LPC18XX_WDT_MOD_WDRESET
;
144 writel(val
, lpc18xx_wdt
->base
+ LPC18XX_WDT_MOD
);
147 * Setting the WDEN bit in the WDMOD register is not sufficient to
148 * enable the Watchdog. A valid feed sequence must be completed after
149 * setting WDEN before the Watchdog is capable of generating a reset.
151 lpc18xx_wdt_feed(wdt_dev
);
156 static int lpc18xx_wdt_restart(struct watchdog_device
*wdt_dev
,
157 unsigned long action
, void *data
)
159 struct lpc18xx_wdt_dev
*lpc18xx_wdt
= watchdog_get_drvdata(wdt_dev
);
164 * Incorrect feed sequence causes immediate watchdog reset if enabled.
166 spin_lock_irqsave(&lpc18xx_wdt
->lock
, flags
);
168 val
= readl(lpc18xx_wdt
->base
+ LPC18XX_WDT_MOD
);
169 val
|= LPC18XX_WDT_MOD_WDEN
;
170 val
|= LPC18XX_WDT_MOD_WDRESET
;
171 writel(val
, lpc18xx_wdt
->base
+ LPC18XX_WDT_MOD
);
173 writel(LPC18XX_WDT_FEED_MAGIC1
, lpc18xx_wdt
->base
+ LPC18XX_WDT_FEED
);
174 writel(LPC18XX_WDT_FEED_MAGIC2
, lpc18xx_wdt
->base
+ LPC18XX_WDT_FEED
);
176 writel(LPC18XX_WDT_FEED_MAGIC1
, lpc18xx_wdt
->base
+ LPC18XX_WDT_FEED
);
177 writel(LPC18XX_WDT_FEED_MAGIC1
, lpc18xx_wdt
->base
+ LPC18XX_WDT_FEED
);
179 spin_unlock_irqrestore(&lpc18xx_wdt
->lock
, flags
);
184 static const struct watchdog_info lpc18xx_wdt_info
= {
185 .identity
= "NXP LPC18xx Watchdog",
186 .options
= WDIOF_SETTIMEOUT
|
187 WDIOF_KEEPALIVEPING
|
191 static const struct watchdog_ops lpc18xx_wdt_ops
= {
192 .owner
= THIS_MODULE
,
193 .start
= lpc18xx_wdt_start
,
194 .stop
= lpc18xx_wdt_stop
,
195 .ping
= lpc18xx_wdt_feed
,
196 .set_timeout
= lpc18xx_wdt_set_timeout
,
197 .get_timeleft
= lpc18xx_wdt_get_timeleft
,
198 .restart
= lpc18xx_wdt_restart
,
201 static int lpc18xx_wdt_probe(struct platform_device
*pdev
)
203 struct lpc18xx_wdt_dev
*lpc18xx_wdt
;
204 struct device
*dev
= &pdev
->dev
;
205 struct resource
*res
;
208 lpc18xx_wdt
= devm_kzalloc(dev
, sizeof(*lpc18xx_wdt
), GFP_KERNEL
);
212 res
= platform_get_resource(pdev
, IORESOURCE_MEM
, 0);
213 lpc18xx_wdt
->base
= devm_ioremap_resource(dev
, res
);
214 if (IS_ERR(lpc18xx_wdt
->base
))
215 return PTR_ERR(lpc18xx_wdt
->base
);
217 lpc18xx_wdt
->reg_clk
= devm_clk_get(dev
, "reg");
218 if (IS_ERR(lpc18xx_wdt
->reg_clk
)) {
219 dev_err(dev
, "failed to get the reg clock\n");
220 return PTR_ERR(lpc18xx_wdt
->reg_clk
);
223 lpc18xx_wdt
->wdt_clk
= devm_clk_get(dev
, "wdtclk");
224 if (IS_ERR(lpc18xx_wdt
->wdt_clk
)) {
225 dev_err(dev
, "failed to get the wdt clock\n");
226 return PTR_ERR(lpc18xx_wdt
->wdt_clk
);
229 ret
= clk_prepare_enable(lpc18xx_wdt
->reg_clk
);
231 dev_err(dev
, "could not prepare or enable sys clock\n");
235 ret
= clk_prepare_enable(lpc18xx_wdt
->wdt_clk
);
237 dev_err(dev
, "could not prepare or enable wdt clock\n");
238 goto disable_reg_clk
;
241 /* We use the clock rate to calculate timeouts */
242 lpc18xx_wdt
->clk_rate
= clk_get_rate(lpc18xx_wdt
->wdt_clk
);
243 if (lpc18xx_wdt
->clk_rate
== 0) {
244 dev_err(dev
, "failed to get clock rate\n");
246 goto disable_wdt_clk
;
249 lpc18xx_wdt
->wdt_dev
.info
= &lpc18xx_wdt_info
;
250 lpc18xx_wdt
->wdt_dev
.ops
= &lpc18xx_wdt_ops
;
252 lpc18xx_wdt
->wdt_dev
.min_timeout
= DIV_ROUND_UP(LPC18XX_WDT_TC_MIN
*
253 LPC18XX_WDT_CLK_DIV
, lpc18xx_wdt
->clk_rate
);
255 lpc18xx_wdt
->wdt_dev
.max_timeout
= (LPC18XX_WDT_TC_MAX
*
256 LPC18XX_WDT_CLK_DIV
) / lpc18xx_wdt
->clk_rate
;
258 lpc18xx_wdt
->wdt_dev
.timeout
= min(lpc18xx_wdt
->wdt_dev
.max_timeout
,
259 LPC18XX_WDT_DEF_TIMEOUT
);
261 spin_lock_init(&lpc18xx_wdt
->lock
);
263 lpc18xx_wdt
->wdt_dev
.parent
= dev
;
264 watchdog_set_drvdata(&lpc18xx_wdt
->wdt_dev
, lpc18xx_wdt
);
266 ret
= watchdog_init_timeout(&lpc18xx_wdt
->wdt_dev
, heartbeat
, dev
);
268 __lpc18xx_wdt_set_timeout(lpc18xx_wdt
);
270 setup_timer(&lpc18xx_wdt
->timer
, lpc18xx_wdt_timer_feed
,
271 (unsigned long)&lpc18xx_wdt
->wdt_dev
);
273 watchdog_set_nowayout(&lpc18xx_wdt
->wdt_dev
, nowayout
);
274 watchdog_set_restart_priority(&lpc18xx_wdt
->wdt_dev
, 128);
276 platform_set_drvdata(pdev
, lpc18xx_wdt
);
278 ret
= watchdog_register_device(&lpc18xx_wdt
->wdt_dev
);
280 goto disable_wdt_clk
;
285 clk_disable_unprepare(lpc18xx_wdt
->wdt_clk
);
287 clk_disable_unprepare(lpc18xx_wdt
->reg_clk
);
291 static void lpc18xx_wdt_shutdown(struct platform_device
*pdev
)
293 struct lpc18xx_wdt_dev
*lpc18xx_wdt
= platform_get_drvdata(pdev
);
295 lpc18xx_wdt_stop(&lpc18xx_wdt
->wdt_dev
);
298 static int lpc18xx_wdt_remove(struct platform_device
*pdev
)
300 struct lpc18xx_wdt_dev
*lpc18xx_wdt
= platform_get_drvdata(pdev
);
302 dev_warn(&pdev
->dev
, "I quit now, hardware will probably reboot!\n");
303 del_timer(&lpc18xx_wdt
->timer
);
305 watchdog_unregister_device(&lpc18xx_wdt
->wdt_dev
);
306 clk_disable_unprepare(lpc18xx_wdt
->wdt_clk
);
307 clk_disable_unprepare(lpc18xx_wdt
->reg_clk
);
312 static const struct of_device_id lpc18xx_wdt_match
[] = {
313 { .compatible
= "nxp,lpc1850-wwdt" },
316 MODULE_DEVICE_TABLE(of
, lpc18xx_wdt_match
);
318 static struct platform_driver lpc18xx_wdt_driver
= {
320 .name
= "lpc18xx-wdt",
321 .of_match_table
= lpc18xx_wdt_match
,
323 .probe
= lpc18xx_wdt_probe
,
324 .remove
= lpc18xx_wdt_remove
,
325 .shutdown
= lpc18xx_wdt_shutdown
,
327 module_platform_driver(lpc18xx_wdt_driver
);
329 MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>");
330 MODULE_DESCRIPTION("NXP LPC18xx Watchdog Timer Driver");
331 MODULE_LICENSE("GPL v2");