1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Driver for Atmel SAMA5D4 Watchdog Timer
4 *
5 * Copyright (C) 2015-2019 Microchip Technology Inc. and its subsidiaries
6 */
7
8 #include <linux/delay.h>
9 #include <linux/interrupt.h>
10 #include <linux/io.h>
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/of.h>
14 #include <linux/of_device.h>
15 #include <linux/of_irq.h>
16 #include <linux/platform_device.h>
17 #include <linux/reboot.h>
18 #include <linux/watchdog.h>
19
20 #include "at91sam9_wdt.h"
21
22 /* minimum and maximum watchdog timeout, in seconds */
23 #define MIN_WDT_TIMEOUT 1
24 #define MAX_WDT_TIMEOUT 16
25 #define WDT_DEFAULT_TIMEOUT MAX_WDT_TIMEOUT
26
27 #define WDT_SEC2TICKS(s) ((s) ? (((s) << 8) - 1) : 0)
28
29 struct sama5d4_wdt {
30 struct watchdog_device wdd;
31 void __iomem *reg_base;
32 u32 mr;
33 u32 ir;
34 unsigned long last_ping;
35 bool need_irq;
36 bool sam9x60_support;
37 };
38
39 static int wdt_timeout;
40 static bool nowayout = WATCHDOG_NOWAYOUT;
41
42 module_param(wdt_timeout, int, 0);
43 MODULE_PARM_DESC(wdt_timeout,
44 "Watchdog timeout in seconds. (default = "
45 __MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
46
47 module_param(nowayout, bool, 0);
48 MODULE_PARM_DESC(nowayout,
49 "Watchdog cannot be stopped once started (default="
50 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
51
52 #define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))
53
54 #define wdt_read(wdt, field) \
55 readl_relaxed((wdt)->reg_base + (field))
56
57 /* 4 slow clock periods is 4/32768 = 122.07µs*/
58 #define WDT_DELAY usecs_to_jiffies(123)
59
wdt_write(struct sama5d4_wdt * wdt,u32 field,u32 val)60 static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val)
61 {
62 /*
63 * WDT_CR and WDT_MR must not be modified within three slow clock
64 * periods following a restart of the watchdog performed by a write
65 * access in WDT_CR.
66 */
67 while (time_before(jiffies, wdt->last_ping + WDT_DELAY))
68 usleep_range(30, 125);
69 writel_relaxed(val, wdt->reg_base + field);
70 wdt->last_ping = jiffies;
71 }
72
wdt_write_nosleep(struct sama5d4_wdt * wdt,u32 field,u32 val)73 static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val)
74 {
75 if (time_before(jiffies, wdt->last_ping + WDT_DELAY))
76 udelay(123);
77 writel_relaxed(val, wdt->reg_base + field);
78 wdt->last_ping = jiffies;
79 }
80
sama5d4_wdt_start(struct watchdog_device * wdd)81 static int sama5d4_wdt_start(struct watchdog_device *wdd)
82 {
83 struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
84
85 if (wdt->sam9x60_support) {
86 writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IER);
87 wdt->mr &= ~AT91_SAM9X60_WDDIS;
88 } else {
89 wdt->mr &= ~AT91_WDT_WDDIS;
90 }
91 wdt_write(wdt, AT91_WDT_MR, wdt->mr);
92
93 return 0;
94 }
95
sama5d4_wdt_stop(struct watchdog_device * wdd)96 static int sama5d4_wdt_stop(struct watchdog_device *wdd)
97 {
98 struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
99
100 if (wdt->sam9x60_support) {
101 writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IDR);
102 wdt->mr |= AT91_SAM9X60_WDDIS;
103 } else {
104 wdt->mr |= AT91_WDT_WDDIS;
105 }
106 wdt_write(wdt, AT91_WDT_MR, wdt->mr);
107
108 return 0;
109 }
110
sama5d4_wdt_ping(struct watchdog_device * wdd)111 static int sama5d4_wdt_ping(struct watchdog_device *wdd)
112 {
113 struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
114
115 wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
116
117 return 0;
118 }
119
sama5d4_wdt_set_timeout(struct watchdog_device * wdd,unsigned int timeout)120 static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
121 unsigned int timeout)
122 {
123 struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
124 u32 value = WDT_SEC2TICKS(timeout);
125
126 if (wdt->sam9x60_support) {
127 wdt_write(wdt, AT91_SAM9X60_WLR,
128 AT91_SAM9X60_SET_COUNTER(value));
129
130 wdd->timeout = timeout;
131 return 0;
132 }
133
134 wdt->mr &= ~AT91_WDT_WDV;
135 wdt->mr |= AT91_WDT_SET_WDV(value);
136
137 /*
138 * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
139 * setting the WDDIS bit, and while it is set, the fields WDV and WDD
140 * must not be modified.
141 * If the watchdog is enabled, then the timeout can be updated. Else,
142 * wait that the user enables it.
143 */
144 if (wdt_enabled)
145 wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
146
147 wdd->timeout = timeout;
148
149 return 0;
150 }
151
152 static const struct watchdog_info sama5d4_wdt_info = {
153 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
154 .identity = "Atmel SAMA5D4 Watchdog",
155 };
156
157 static const struct watchdog_ops sama5d4_wdt_ops = {
158 .owner = THIS_MODULE,
159 .start = sama5d4_wdt_start,
160 .stop = sama5d4_wdt_stop,
161 .ping = sama5d4_wdt_ping,
162 .set_timeout = sama5d4_wdt_set_timeout,
163 };
164
sama5d4_wdt_irq_handler(int irq,void * dev_id)165 static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
166 {
167 struct sama5d4_wdt *wdt = platform_get_drvdata(dev_id);
168 u32 reg;
169
170 if (wdt->sam9x60_support)
171 reg = wdt_read(wdt, AT91_SAM9X60_ISR);
172 else
173 reg = wdt_read(wdt, AT91_WDT_SR);
174
175 if (reg) {
176 pr_crit("Atmel Watchdog Software Reset\n");
177 emergency_restart();
178 pr_crit("Reboot didn't succeed\n");
179 }
180
181 return IRQ_HANDLED;
182 }
183
of_sama5d4_wdt_init(struct device_node * np,struct sama5d4_wdt * wdt)184 static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
185 {
186 const char *tmp;
187
188 if (wdt->sam9x60_support)
189 wdt->mr = AT91_SAM9X60_WDDIS;
190 else
191 wdt->mr = AT91_WDT_WDDIS;
192
193 if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
194 !strcmp(tmp, "software"))
195 wdt->need_irq = true;
196
197 if (of_property_read_bool(np, "atmel,idle-halt"))
198 wdt->mr |= AT91_WDT_WDIDLEHLT;
199
200 if (of_property_read_bool(np, "atmel,dbg-halt"))
201 wdt->mr |= AT91_WDT_WDDBGHLT;
202
203 return 0;
204 }
205
sama5d4_wdt_init(struct sama5d4_wdt * wdt)206 static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
207 {
208 u32 reg, val;
209
210 val = WDT_SEC2TICKS(WDT_DEFAULT_TIMEOUT);
211 /*
212 * When booting and resuming, the bootloader may have changed the
213 * watchdog configuration.
214 * If the watchdog is already running, we can safely update it.
215 * Else, we have to disable it properly.
216 */
217 if (!wdt_enabled) {
218 reg = wdt_read(wdt, AT91_WDT_MR);
219 if (wdt->sam9x60_support && (!(reg & AT91_SAM9X60_WDDIS)))
220 wdt_write_nosleep(wdt, AT91_WDT_MR,
221 reg | AT91_SAM9X60_WDDIS);
222 else if (!wdt->sam9x60_support &&
223 (!(reg & AT91_WDT_WDDIS)))
224 wdt_write_nosleep(wdt, AT91_WDT_MR,
225 reg | AT91_WDT_WDDIS);
226 }
227
228 if (wdt->sam9x60_support) {
229 if (wdt->need_irq)
230 wdt->ir = AT91_SAM9X60_PERINT;
231 else
232 wdt->mr |= AT91_SAM9X60_PERIODRST;
233
234 wdt_write(wdt, AT91_SAM9X60_IER, wdt->ir);
235 wdt_write(wdt, AT91_SAM9X60_WLR, AT91_SAM9X60_SET_COUNTER(val));
236 } else {
237 wdt->mr |= AT91_WDT_SET_WDD(WDT_SEC2TICKS(MAX_WDT_TIMEOUT));
238 wdt->mr |= AT91_WDT_SET_WDV(val);
239
240 if (wdt->need_irq)
241 wdt->mr |= AT91_WDT_WDFIEN;
242 else
243 wdt->mr |= AT91_WDT_WDRSTEN;
244 }
245
246 wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr);
247
248 return 0;
249 }
250
sama5d4_wdt_probe(struct platform_device * pdev)251 static int sama5d4_wdt_probe(struct platform_device *pdev)
252 {
253 struct device *dev = &pdev->dev;
254 struct watchdog_device *wdd;
255 struct sama5d4_wdt *wdt;
256 void __iomem *regs;
257 u32 irq = 0;
258 int ret;
259
260 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
261 if (!wdt)
262 return -ENOMEM;
263
264 wdd = &wdt->wdd;
265 wdd->timeout = WDT_DEFAULT_TIMEOUT;
266 wdd->info = &sama5d4_wdt_info;
267 wdd->ops = &sama5d4_wdt_ops;
268 wdd->min_timeout = MIN_WDT_TIMEOUT;
269 wdd->max_timeout = MAX_WDT_TIMEOUT;
270 wdt->last_ping = jiffies;
271
272 if (of_device_is_compatible(dev->of_node, "microchip,sam9x60-wdt") ||
273 of_device_is_compatible(dev->of_node, "microchip,sama7g5-wdt"))
274 wdt->sam9x60_support = true;
275
276 watchdog_set_drvdata(wdd, wdt);
277
278 regs = devm_platform_ioremap_resource(pdev, 0);
279 if (IS_ERR(regs))
280 return PTR_ERR(regs);
281
282 wdt->reg_base = regs;
283
284 ret = of_sama5d4_wdt_init(dev->of_node, wdt);
285 if (ret)
286 return ret;
287
288 if (wdt->need_irq) {
289 irq = irq_of_parse_and_map(dev->of_node, 0);
290 if (!irq) {
291 dev_warn(dev, "failed to get IRQ from DT\n");
292 wdt->need_irq = false;
293 }
294 }
295
296 if (wdt->need_irq) {
297 ret = devm_request_irq(dev, irq, sama5d4_wdt_irq_handler,
298 IRQF_SHARED | IRQF_IRQPOLL |
299 IRQF_NO_SUSPEND, pdev->name, pdev);
300 if (ret) {
301 dev_err(dev, "cannot register interrupt handler\n");
302 return ret;
303 }
304 }
305
306 watchdog_init_timeout(wdd, wdt_timeout, dev);
307
308 ret = sama5d4_wdt_init(wdt);
309 if (ret)
310 return ret;
311
312 watchdog_set_nowayout(wdd, nowayout);
313
314 watchdog_stop_on_unregister(wdd);
315 ret = devm_watchdog_register_device(dev, wdd);
316 if (ret)
317 return ret;
318
319 platform_set_drvdata(pdev, wdt);
320
321 dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
322 wdd->timeout, nowayout);
323
324 return 0;
325 }
326
327 static const struct of_device_id sama5d4_wdt_of_match[] = {
328 {
329 .compatible = "atmel,sama5d4-wdt",
330 },
331 {
332 .compatible = "microchip,sam9x60-wdt",
333 },
334 {
335 .compatible = "microchip,sama7g5-wdt",
336 },
337
338 { }
339 };
340 MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
341
sama5d4_wdt_suspend_late(struct device * dev)342 static int sama5d4_wdt_suspend_late(struct device *dev)
343 {
344 struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
345
346 if (watchdog_active(&wdt->wdd))
347 sama5d4_wdt_stop(&wdt->wdd);
348
349 return 0;
350 }
351
sama5d4_wdt_resume_early(struct device * dev)352 static int sama5d4_wdt_resume_early(struct device *dev)
353 {
354 struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
355
356 /*
357 * FIXME: writing MR also pings the watchdog which may not be desired.
358 * This should only be done when the registers are lost on suspend but
359 * there is no way to get this information right now.
360 */
361 sama5d4_wdt_init(wdt);
362
363 if (watchdog_active(&wdt->wdd))
364 sama5d4_wdt_start(&wdt->wdd);
365
366 return 0;
367 }
368
369 static const struct dev_pm_ops sama5d4_wdt_pm_ops = {
370 LATE_SYSTEM_SLEEP_PM_OPS(sama5d4_wdt_suspend_late,
371 sama5d4_wdt_resume_early)
372 };
373
374 static struct platform_driver sama5d4_wdt_driver = {
375 .probe = sama5d4_wdt_probe,
376 .driver = {
377 .name = "sama5d4_wdt",
378 .pm = pm_sleep_ptr(&sama5d4_wdt_pm_ops),
379 .of_match_table = sama5d4_wdt_of_match,
380 }
381 };
382 module_platform_driver(sama5d4_wdt_driver);
383
384 MODULE_AUTHOR("Atmel Corporation");
385 MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
386 MODULE_LICENSE("GPL v2");
387