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_irq.h>
15#include <linux/platform_device.h>
16#include <linux/reboot.h>
17#include <linux/watchdog.h>
18
19#include "at91sam9_wdt.h"
20
21/* minimum and maximum watchdog timeout, in seconds */
22#define MIN_WDT_TIMEOUT 1
23#define MAX_WDT_TIMEOUT 16
24#define WDT_DEFAULT_TIMEOUT MAX_WDT_TIMEOUT
25
26#define WDT_SEC2TICKS(s) ((s) ? (((s) << 8) - 1) : 0)
27
28struct sama5d4_wdt {
29 struct watchdog_device wdd;
30 void __iomem *reg_base;
31 u32 mr;
32 u32 ir;
33 unsigned long last_ping;
34 bool need_irq;
35 bool sam9x60_support;
36};
37
38static int wdt_timeout;
39static bool nowayout = WATCHDOG_NOWAYOUT;
40
41module_param(wdt_timeout, int, 0);
42MODULE_PARM_DESC(wdt_timeout,
43 "Watchdog timeout in seconds. (default = "
44 __MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
45
46module_param(nowayout, bool, 0);
47MODULE_PARM_DESC(nowayout,
48 "Watchdog cannot be stopped once started (default="
49 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
50
51#define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))
52
53#define wdt_read(wdt, field) \
54 readl_relaxed((wdt)->reg_base + (field))
55
56/* 4 slow clock periods is 4/32768 = 122.07µs*/
57#define WDT_DELAY usecs_to_jiffies(123)
58
59static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val)
60{
61 /*
62 * WDT_CR and WDT_MR must not be modified within three slow clock
63 * periods following a restart of the watchdog performed by a write
64 * access in WDT_CR.
65 */
66 while (time_before(jiffies, wdt->last_ping + WDT_DELAY))
67 usleep_range(min: 30, max: 125);
68 writel_relaxed(val, wdt->reg_base + field);
69 wdt->last_ping = jiffies;
70}
71
72static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val)
73{
74 if (time_before(jiffies, wdt->last_ping + WDT_DELAY))
75 udelay(usec: 123);
76 writel_relaxed(val, wdt->reg_base + field);
77 wdt->last_ping = jiffies;
78}
79
80static int sama5d4_wdt_start(struct watchdog_device *wdd)
81{
82 struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
83
84 if (wdt->sam9x60_support) {
85 writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IER);
86 wdt->mr &= ~AT91_SAM9X60_WDDIS;
87 } else {
88 wdt->mr &= ~AT91_WDT_WDDIS;
89 }
90 wdt_write(wdt, AT91_WDT_MR, val: wdt->mr);
91
92 return 0;
93}
94
95static int sama5d4_wdt_stop(struct watchdog_device *wdd)
96{
97 struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
98
99 if (wdt->sam9x60_support) {
100 writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IDR);
101 wdt->mr |= AT91_SAM9X60_WDDIS;
102 } else {
103 wdt->mr |= AT91_WDT_WDDIS;
104 }
105 wdt_write(wdt, AT91_WDT_MR, val: wdt->mr);
106
107 return 0;
108}
109
110static int sama5d4_wdt_ping(struct watchdog_device *wdd)
111{
112 struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
113
114 wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
115
116 return 0;
117}
118
119static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
120 unsigned int timeout)
121{
122 struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
123 u32 value = WDT_SEC2TICKS(timeout);
124
125 if (wdt->sam9x60_support) {
126 wdt_write(wdt, AT91_SAM9X60_WLR,
127 AT91_SAM9X60_SET_COUNTER(value));
128
129 wdd->timeout = timeout;
130 return 0;
131 }
132
133 wdt->mr &= ~AT91_WDT_WDV;
134 wdt->mr |= AT91_WDT_SET_WDV(value);
135
136 /*
137 * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
138 * setting the WDDIS bit, and while it is set, the fields WDV and WDD
139 * must not be modified.
140 * If the watchdog is enabled, then the timeout can be updated. Else,
141 * wait that the user enables it.
142 */
143 if (wdt_enabled)
144 wdt_write(wdt, AT91_WDT_MR, val: wdt->mr & ~AT91_WDT_WDDIS);
145
146 wdd->timeout = timeout;
147
148 return 0;
149}
150
151static const struct watchdog_info sama5d4_wdt_info = {
152 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
153 .identity = "Atmel SAMA5D4 Watchdog",
154};
155
156static const struct watchdog_ops sama5d4_wdt_ops = {
157 .owner = THIS_MODULE,
158 .start = sama5d4_wdt_start,
159 .stop = sama5d4_wdt_stop,
160 .ping = sama5d4_wdt_ping,
161 .set_timeout = sama5d4_wdt_set_timeout,
162};
163
164static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
165{
166 struct sama5d4_wdt *wdt = platform_get_drvdata(pdev: dev_id);
167 u32 reg;
168
169 if (wdt->sam9x60_support)
170 reg = wdt_read(wdt, AT91_SAM9X60_ISR);
171 else
172 reg = wdt_read(wdt, AT91_WDT_SR);
173
174 if (reg) {
175 pr_crit("Atmel Watchdog Software Reset\n");
176 emergency_restart();
177 pr_crit("Reboot didn't succeed\n");
178 }
179
180 return IRQ_HANDLED;
181}
182
183static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
184{
185 const char *tmp;
186
187 if (wdt->sam9x60_support)
188 wdt->mr = AT91_SAM9X60_WDDIS;
189 else
190 wdt->mr = AT91_WDT_WDDIS;
191
192 if (!of_property_read_string(np, propname: "atmel,watchdog-type", out_string: &tmp) &&
193 !strcmp(tmp, "software"))
194 wdt->need_irq = true;
195
196 if (of_property_read_bool(np, propname: "atmel,idle-halt"))
197 wdt->mr |= AT91_WDT_WDIDLEHLT;
198
199 if (of_property_read_bool(np, propname: "atmel,dbg-halt"))
200 wdt->mr |= AT91_WDT_WDDBGHLT;
201
202 return 0;
203}
204
205static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
206{
207 u32 reg, val;
208
209 val = WDT_SEC2TICKS(WDT_DEFAULT_TIMEOUT);
210 /*
211 * When booting and resuming, the bootloader may have changed the
212 * watchdog configuration.
213 * If the watchdog is already running, we can safely update it.
214 * Else, we have to disable it properly.
215 */
216 if (!wdt_enabled) {
217 reg = wdt_read(wdt, AT91_WDT_MR);
218 if (wdt->sam9x60_support && (!(reg & AT91_SAM9X60_WDDIS)))
219 wdt_write_nosleep(wdt, AT91_WDT_MR,
220 val: reg | AT91_SAM9X60_WDDIS);
221 else if (!wdt->sam9x60_support &&
222 (!(reg & AT91_WDT_WDDIS)))
223 wdt_write_nosleep(wdt, AT91_WDT_MR,
224 val: reg | AT91_WDT_WDDIS);
225 }
226
227 if (wdt->sam9x60_support) {
228 if (wdt->need_irq)
229 wdt->ir = AT91_SAM9X60_PERINT;
230 else
231 wdt->mr |= AT91_SAM9X60_PERIODRST;
232
233 wdt_write(wdt, AT91_SAM9X60_IER, val: wdt->ir);
234 wdt_write(wdt, AT91_SAM9X60_WLR, AT91_SAM9X60_SET_COUNTER(val));
235 } else {
236 wdt->mr |= AT91_WDT_SET_WDD(WDT_SEC2TICKS(MAX_WDT_TIMEOUT));
237 wdt->mr |= AT91_WDT_SET_WDV(val);
238
239 if (wdt->need_irq)
240 wdt->mr |= AT91_WDT_WDFIEN;
241 else
242 wdt->mr |= AT91_WDT_WDRSTEN;
243 }
244
245 wdt_write_nosleep(wdt, AT91_WDT_MR, val: wdt->mr);
246
247 return 0;
248}
249
250static int sama5d4_wdt_probe(struct platform_device *pdev)
251{
252 struct device *dev = &pdev->dev;
253 struct watchdog_device *wdd;
254 struct sama5d4_wdt *wdt;
255 void __iomem *regs;
256 u32 irq = 0;
257 u32 reg;
258 int ret;
259
260 wdt = devm_kzalloc(dev, size: 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(device: dev->of_node, "microchip,sam9x60-wdt") ||
273 of_device_is_compatible(device: dev->of_node, "microchip,sama7g5-wdt"))
274 wdt->sam9x60_support = true;
275
276 watchdog_set_drvdata(wdd, data: wdt);
277
278 regs = devm_platform_ioremap_resource(pdev, index: 0);
279 if (IS_ERR(ptr: regs))
280 return PTR_ERR(ptr: regs);
281
282 wdt->reg_base = regs;
283
284 ret = of_sama5d4_wdt_init(np: dev->of_node, wdt);
285 if (ret)
286 return ret;
287
288 if (wdt->need_irq) {
289 irq = irq_of_parse_and_map(node: dev->of_node, index: 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, handler: sama5d4_wdt_irq_handler,
298 IRQF_SHARED | IRQF_IRQPOLL |
299 IRQF_NO_SUSPEND, devname: pdev->name, dev_id: pdev);
300 if (ret) {
301 dev_err(dev, "cannot register interrupt handler\n");
302 return ret;
303 }
304 }
305
306 watchdog_init_timeout(wdd, timeout_parm: wdt_timeout, dev);
307
308 reg = wdt_read(wdt, AT91_WDT_MR);
309 if (!(reg & AT91_WDT_WDDIS)) {
310 wdt->mr &= ~AT91_WDT_WDDIS;
311 set_bit(WDOG_HW_RUNNING, addr: &wdd->status);
312 }
313
314 ret = sama5d4_wdt_init(wdt);
315 if (ret)
316 return ret;
317
318 watchdog_set_nowayout(wdd, nowayout);
319
320 watchdog_stop_on_unregister(wdd);
321 ret = devm_watchdog_register_device(dev, wdd);
322 if (ret)
323 return ret;
324
325 platform_set_drvdata(pdev, data: wdt);
326
327 dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
328 wdd->timeout, nowayout);
329
330 return 0;
331}
332
333static const struct of_device_id sama5d4_wdt_of_match[] = {
334 {
335 .compatible = "atmel,sama5d4-wdt",
336 },
337 {
338 .compatible = "microchip,sam9x60-wdt",
339 },
340 {
341 .compatible = "microchip,sama7g5-wdt",
342 },
343
344 { }
345};
346MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
347
348static int sama5d4_wdt_suspend_late(struct device *dev)
349{
350 struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
351
352 if (watchdog_active(wdd: &wdt->wdd))
353 sama5d4_wdt_stop(wdd: &wdt->wdd);
354
355 return 0;
356}
357
358static int sama5d4_wdt_resume_early(struct device *dev)
359{
360 struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
361
362 /*
363 * FIXME: writing MR also pings the watchdog which may not be desired.
364 * This should only be done when the registers are lost on suspend but
365 * there is no way to get this information right now.
366 */
367 sama5d4_wdt_init(wdt);
368
369 if (watchdog_active(wdd: &wdt->wdd))
370 sama5d4_wdt_start(wdd: &wdt->wdd);
371
372 return 0;
373}
374
375static const struct dev_pm_ops sama5d4_wdt_pm_ops = {
376 LATE_SYSTEM_SLEEP_PM_OPS(sama5d4_wdt_suspend_late,
377 sama5d4_wdt_resume_early)
378};
379
380static struct platform_driver sama5d4_wdt_driver = {
381 .probe = sama5d4_wdt_probe,
382 .driver = {
383 .name = "sama5d4_wdt",
384 .pm = pm_sleep_ptr(&sama5d4_wdt_pm_ops),
385 .of_match_table = sama5d4_wdt_of_match,
386 }
387};
388module_platform_driver(sama5d4_wdt_driver);
389
390MODULE_AUTHOR("Atmel Corporation");
391MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
392MODULE_LICENSE("GPL v2");
393

source code of linux/drivers/watchdog/sama5d4_wdt.c