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1 | /* |
2 | * NXP LPC18xx Watchdog Timer (WDT) | |
3 | * | |
4 | * Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com> | |
5 | * | |
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. | |
9 | * | |
10 | * Notes | |
11 | * ----- | |
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. | |
14 | */ | |
15 | ||
16 | #include <linux/clk.h> | |
17 | #include <linux/io.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/of.h> | |
20 | #include <linux/platform_device.h> | |
21 | #include <linux/reboot.h> | |
22 | #include <linux/watchdog.h> | |
23 | ||
24 | /* Registers */ | |
25 | #define LPC18XX_WDT_MOD 0x00 | |
26 | #define LPC18XX_WDT_MOD_WDEN BIT(0) | |
27 | #define LPC18XX_WDT_MOD_WDRESET BIT(1) | |
28 | ||
29 | #define LPC18XX_WDT_TC 0x04 | |
30 | #define LPC18XX_WDT_TC_MIN 0xff | |
31 | #define LPC18XX_WDT_TC_MAX 0xffffff | |
32 | ||
33 | #define LPC18XX_WDT_FEED 0x08 | |
34 | #define LPC18XX_WDT_FEED_MAGIC1 0xaa | |
35 | #define LPC18XX_WDT_FEED_MAGIC2 0x55 | |
36 | ||
37 | #define LPC18XX_WDT_TV 0x0c | |
38 | ||
39 | /* Clock pre-scaler */ | |
40 | #define LPC18XX_WDT_CLK_DIV 4 | |
41 | ||
42 | /* Timeout values in seconds */ | |
43 | #define LPC18XX_WDT_DEF_TIMEOUT 30U | |
44 | ||
45 | static int heartbeat; | |
46 | module_param(heartbeat, int, 0); | |
47 | MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds (default=" | |
48 | __MODULE_STRING(LPC18XX_WDT_DEF_TIMEOUT) ")"); | |
49 | ||
50 | static bool nowayout = WATCHDOG_NOWAYOUT; | |
51 | module_param(nowayout, bool, 0); | |
52 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" | |
53 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); | |
54 | ||
55 | struct lpc18xx_wdt_dev { | |
56 | struct watchdog_device wdt_dev; | |
57 | struct clk *reg_clk; | |
58 | struct clk *wdt_clk; | |
59 | unsigned long clk_rate; | |
60 | void __iomem *base; | |
61 | struct timer_list timer; | |
62 | struct notifier_block restart_handler; | |
63 | spinlock_t lock; | |
64 | }; | |
65 | ||
66 | static int lpc18xx_wdt_feed(struct watchdog_device *wdt_dev) | |
67 | { | |
68 | struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev); | |
69 | unsigned long flags; | |
70 | ||
71 | /* | |
72 | * An abort condition will occur if an interrupt happens during the feed | |
73 | * sequence. | |
74 | */ | |
75 | spin_lock_irqsave(&lpc18xx_wdt->lock, flags); | |
76 | writel(LPC18XX_WDT_FEED_MAGIC1, lpc18xx_wdt->base + LPC18XX_WDT_FEED); | |
77 | writel(LPC18XX_WDT_FEED_MAGIC2, lpc18xx_wdt->base + LPC18XX_WDT_FEED); | |
78 | spin_unlock_irqrestore(&lpc18xx_wdt->lock, flags); | |
79 | ||
80 | return 0; | |
81 | } | |
82 | ||
83 | static void lpc18xx_wdt_timer_feed(unsigned long data) | |
84 | { | |
85 | struct watchdog_device *wdt_dev = (struct watchdog_device *)data; | |
86 | struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev); | |
87 | ||
88 | lpc18xx_wdt_feed(wdt_dev); | |
89 | ||
90 | /* Use safe value (1/2 of real timeout) */ | |
91 | mod_timer(&lpc18xx_wdt->timer, jiffies + | |
92 | msecs_to_jiffies((wdt_dev->timeout * MSEC_PER_SEC) / 2)); | |
93 | } | |
94 | ||
95 | /* | |
96 | * Since LPC18xx Watchdog cannot be disabled in hardware, we must keep feeding | |
97 | * it with a timer until userspace watchdog software takes over. | |
98 | */ | |
99 | static int lpc18xx_wdt_stop(struct watchdog_device *wdt_dev) | |
100 | { | |
101 | lpc18xx_wdt_timer_feed((unsigned long)wdt_dev); | |
102 | ||
103 | return 0; | |
104 | } | |
105 | ||
106 | static void __lpc18xx_wdt_set_timeout(struct lpc18xx_wdt_dev *lpc18xx_wdt) | |
107 | { | |
108 | unsigned int val; | |
109 | ||
110 | val = DIV_ROUND_UP(lpc18xx_wdt->wdt_dev.timeout * lpc18xx_wdt->clk_rate, | |
111 | LPC18XX_WDT_CLK_DIV); | |
112 | writel(val, lpc18xx_wdt->base + LPC18XX_WDT_TC); | |
113 | } | |
114 | ||
115 | static int lpc18xx_wdt_set_timeout(struct watchdog_device *wdt_dev, | |
116 | unsigned int new_timeout) | |
117 | { | |
118 | struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev); | |
119 | ||
120 | lpc18xx_wdt->wdt_dev.timeout = new_timeout; | |
121 | __lpc18xx_wdt_set_timeout(lpc18xx_wdt); | |
122 | ||
123 | return 0; | |
124 | } | |
125 | ||
6cd8a1b9 | 126 | static unsigned int lpc18xx_wdt_get_timeleft(struct watchdog_device *wdt_dev) |
7c25f8c9 AA |
127 | { |
128 | struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev); | |
129 | unsigned int val; | |
130 | ||
131 | val = readl(lpc18xx_wdt->base + LPC18XX_WDT_TV); | |
132 | return (val * LPC18XX_WDT_CLK_DIV) / lpc18xx_wdt->clk_rate; | |
133 | } | |
134 | ||
135 | static int lpc18xx_wdt_start(struct watchdog_device *wdt_dev) | |
136 | { | |
137 | struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev); | |
138 | unsigned int val; | |
139 | ||
140 | if (timer_pending(&lpc18xx_wdt->timer)) | |
141 | del_timer(&lpc18xx_wdt->timer); | |
142 | ||
143 | val = readl(lpc18xx_wdt->base + LPC18XX_WDT_MOD); | |
144 | val |= LPC18XX_WDT_MOD_WDEN; | |
145 | val |= LPC18XX_WDT_MOD_WDRESET; | |
146 | writel(val, lpc18xx_wdt->base + LPC18XX_WDT_MOD); | |
147 | ||
148 | /* | |
149 | * Setting the WDEN bit in the WDMOD register is not sufficient to | |
150 | * enable the Watchdog. A valid feed sequence must be completed after | |
151 | * setting WDEN before the Watchdog is capable of generating a reset. | |
152 | */ | |
153 | lpc18xx_wdt_feed(wdt_dev); | |
154 | ||
155 | return 0; | |
156 | } | |
157 | ||
158 | static struct watchdog_info lpc18xx_wdt_info = { | |
159 | .identity = "NXP LPC18xx Watchdog", | |
160 | .options = WDIOF_SETTIMEOUT | | |
161 | WDIOF_KEEPALIVEPING | | |
162 | WDIOF_MAGICCLOSE, | |
163 | }; | |
164 | ||
165 | static const struct watchdog_ops lpc18xx_wdt_ops = { | |
166 | .owner = THIS_MODULE, | |
167 | .start = lpc18xx_wdt_start, | |
168 | .stop = lpc18xx_wdt_stop, | |
169 | .ping = lpc18xx_wdt_feed, | |
170 | .set_timeout = lpc18xx_wdt_set_timeout, | |
171 | .get_timeleft = lpc18xx_wdt_get_timeleft, | |
172 | }; | |
173 | ||
174 | static int lpc18xx_wdt_restart(struct notifier_block *this, unsigned long mode, | |
175 | void *cmd) | |
176 | { | |
177 | struct lpc18xx_wdt_dev *lpc18xx_wdt = container_of(this, | |
178 | struct lpc18xx_wdt_dev, restart_handler); | |
179 | unsigned long flags; | |
180 | int val; | |
181 | ||
182 | /* | |
183 | * Incorrect feed sequence causes immediate watchdog reset if enabled. | |
184 | */ | |
185 | spin_lock_irqsave(&lpc18xx_wdt->lock, flags); | |
186 | ||
187 | val = readl(lpc18xx_wdt->base + LPC18XX_WDT_MOD); | |
188 | val |= LPC18XX_WDT_MOD_WDEN; | |
189 | val |= LPC18XX_WDT_MOD_WDRESET; | |
190 | writel(val, lpc18xx_wdt->base + LPC18XX_WDT_MOD); | |
191 | ||
192 | writel(LPC18XX_WDT_FEED_MAGIC1, lpc18xx_wdt->base + LPC18XX_WDT_FEED); | |
193 | writel(LPC18XX_WDT_FEED_MAGIC2, lpc18xx_wdt->base + LPC18XX_WDT_FEED); | |
194 | ||
195 | writel(LPC18XX_WDT_FEED_MAGIC1, lpc18xx_wdt->base + LPC18XX_WDT_FEED); | |
196 | writel(LPC18XX_WDT_FEED_MAGIC1, lpc18xx_wdt->base + LPC18XX_WDT_FEED); | |
197 | ||
198 | spin_unlock_irqrestore(&lpc18xx_wdt->lock, flags); | |
199 | ||
200 | return NOTIFY_OK; | |
201 | } | |
202 | ||
203 | static int lpc18xx_wdt_probe(struct platform_device *pdev) | |
204 | { | |
205 | struct lpc18xx_wdt_dev *lpc18xx_wdt; | |
206 | struct device *dev = &pdev->dev; | |
207 | struct resource *res; | |
208 | int ret; | |
209 | ||
210 | lpc18xx_wdt = devm_kzalloc(dev, sizeof(*lpc18xx_wdt), GFP_KERNEL); | |
211 | if (!lpc18xx_wdt) | |
212 | return -ENOMEM; | |
213 | ||
214 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
215 | lpc18xx_wdt->base = devm_ioremap_resource(dev, res); | |
216 | if (IS_ERR(lpc18xx_wdt->base)) | |
217 | return PTR_ERR(lpc18xx_wdt->base); | |
218 | ||
219 | lpc18xx_wdt->reg_clk = devm_clk_get(dev, "reg"); | |
220 | if (IS_ERR(lpc18xx_wdt->reg_clk)) { | |
221 | dev_err(dev, "failed to get the reg clock\n"); | |
222 | return PTR_ERR(lpc18xx_wdt->reg_clk); | |
223 | } | |
224 | ||
225 | lpc18xx_wdt->wdt_clk = devm_clk_get(dev, "wdtclk"); | |
226 | if (IS_ERR(lpc18xx_wdt->wdt_clk)) { | |
227 | dev_err(dev, "failed to get the wdt clock\n"); | |
228 | return PTR_ERR(lpc18xx_wdt->wdt_clk); | |
229 | } | |
230 | ||
231 | ret = clk_prepare_enable(lpc18xx_wdt->reg_clk); | |
232 | if (ret) { | |
233 | dev_err(dev, "could not prepare or enable sys clock\n"); | |
234 | return ret; | |
235 | } | |
236 | ||
237 | ret = clk_prepare_enable(lpc18xx_wdt->wdt_clk); | |
238 | if (ret) { | |
239 | dev_err(dev, "could not prepare or enable wdt clock\n"); | |
240 | goto disable_reg_clk; | |
241 | } | |
242 | ||
243 | /* We use the clock rate to calculate timeouts */ | |
244 | lpc18xx_wdt->clk_rate = clk_get_rate(lpc18xx_wdt->wdt_clk); | |
245 | if (lpc18xx_wdt->clk_rate == 0) { | |
246 | dev_err(dev, "failed to get clock rate\n"); | |
247 | ret = -EINVAL; | |
248 | goto disable_wdt_clk; | |
249 | } | |
250 | ||
251 | lpc18xx_wdt->wdt_dev.info = &lpc18xx_wdt_info; | |
252 | lpc18xx_wdt->wdt_dev.ops = &lpc18xx_wdt_ops; | |
253 | ||
254 | lpc18xx_wdt->wdt_dev.min_timeout = DIV_ROUND_UP(LPC18XX_WDT_TC_MIN * | |
255 | LPC18XX_WDT_CLK_DIV, lpc18xx_wdt->clk_rate); | |
256 | ||
257 | lpc18xx_wdt->wdt_dev.max_timeout = (LPC18XX_WDT_TC_MAX * | |
258 | LPC18XX_WDT_CLK_DIV) / lpc18xx_wdt->clk_rate; | |
259 | ||
260 | lpc18xx_wdt->wdt_dev.timeout = min(lpc18xx_wdt->wdt_dev.max_timeout, | |
261 | LPC18XX_WDT_DEF_TIMEOUT); | |
262 | ||
263 | spin_lock_init(&lpc18xx_wdt->lock); | |
264 | ||
265 | lpc18xx_wdt->wdt_dev.parent = dev; | |
266 | watchdog_set_drvdata(&lpc18xx_wdt->wdt_dev, lpc18xx_wdt); | |
267 | ||
268 | ret = watchdog_init_timeout(&lpc18xx_wdt->wdt_dev, heartbeat, dev); | |
269 | ||
270 | __lpc18xx_wdt_set_timeout(lpc18xx_wdt); | |
271 | ||
272 | setup_timer(&lpc18xx_wdt->timer, lpc18xx_wdt_timer_feed, | |
273 | (unsigned long)&lpc18xx_wdt->wdt_dev); | |
274 | ||
275 | watchdog_set_nowayout(&lpc18xx_wdt->wdt_dev, nowayout); | |
276 | ||
277 | platform_set_drvdata(pdev, lpc18xx_wdt); | |
278 | ||
279 | ret = watchdog_register_device(&lpc18xx_wdt->wdt_dev); | |
280 | if (ret) | |
281 | goto disable_wdt_clk; | |
282 | ||
283 | lpc18xx_wdt->restart_handler.notifier_call = lpc18xx_wdt_restart; | |
284 | lpc18xx_wdt->restart_handler.priority = 128; | |
285 | ret = register_restart_handler(&lpc18xx_wdt->restart_handler); | |
286 | if (ret) | |
287 | dev_warn(dev, "failed to register restart handler: %d\n", ret); | |
288 | ||
289 | return 0; | |
290 | ||
291 | disable_wdt_clk: | |
292 | clk_disable_unprepare(lpc18xx_wdt->wdt_clk); | |
293 | disable_reg_clk: | |
294 | clk_disable_unprepare(lpc18xx_wdt->reg_clk); | |
295 | return ret; | |
296 | } | |
297 | ||
298 | static void lpc18xx_wdt_shutdown(struct platform_device *pdev) | |
299 | { | |
300 | struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev); | |
301 | ||
302 | lpc18xx_wdt_stop(&lpc18xx_wdt->wdt_dev); | |
303 | } | |
304 | ||
305 | static int lpc18xx_wdt_remove(struct platform_device *pdev) | |
306 | { | |
307 | struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev); | |
308 | ||
309 | unregister_restart_handler(&lpc18xx_wdt->restart_handler); | |
310 | ||
311 | dev_warn(&pdev->dev, "I quit now, hardware will probably reboot!\n"); | |
312 | del_timer(&lpc18xx_wdt->timer); | |
313 | ||
314 | watchdog_unregister_device(&lpc18xx_wdt->wdt_dev); | |
315 | clk_disable_unprepare(lpc18xx_wdt->wdt_clk); | |
316 | clk_disable_unprepare(lpc18xx_wdt->reg_clk); | |
317 | ||
318 | return 0; | |
319 | } | |
320 | ||
321 | static const struct of_device_id lpc18xx_wdt_match[] = { | |
322 | { .compatible = "nxp,lpc1850-wwdt" }, | |
323 | {} | |
324 | }; | |
325 | MODULE_DEVICE_TABLE(of, lpc18xx_wdt_match); | |
326 | ||
327 | static struct platform_driver lpc18xx_wdt_driver = { | |
328 | .driver = { | |
329 | .name = "lpc18xx-wdt", | |
330 | .of_match_table = lpc18xx_wdt_match, | |
331 | }, | |
332 | .probe = lpc18xx_wdt_probe, | |
333 | .remove = lpc18xx_wdt_remove, | |
334 | .shutdown = lpc18xx_wdt_shutdown, | |
335 | }; | |
336 | module_platform_driver(lpc18xx_wdt_driver); | |
337 | ||
338 | MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>"); | |
339 | MODULE_DESCRIPTION("NXP LPC18xx Watchdog Timer Driver"); | |
340 | MODULE_LICENSE("GPL v2"); |