xref: /linux/drivers/watchdog/sama5d4_wdt.c (revision 905e46acd3272d04566fec49afbd7ad9e2ed9ae3)
1 /*
2  * Driver for Atmel SAMA5D4 Watchdog Timer
3  *
4  * Copyright (C) 2015 Atmel Corporation
5  *
6  * Licensed under GPLv2.
7  */
8 
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 
28 struct sama5d4_wdt {
29 	struct watchdog_device	wdd;
30 	void __iomem		*reg_base;
31 	u32			mr;
32 };
33 
34 static int wdt_timeout = WDT_DEFAULT_TIMEOUT;
35 static bool nowayout = WATCHDOG_NOWAYOUT;
36 
37 module_param(wdt_timeout, int, 0);
38 MODULE_PARM_DESC(wdt_timeout,
39 	"Watchdog timeout in seconds. (default = "
40 	__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
41 
42 module_param(nowayout, bool, 0);
43 MODULE_PARM_DESC(nowayout,
44 	"Watchdog cannot be stopped once started (default="
45 	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
46 
47 #define wdt_read(wdt, field) \
48 	readl_relaxed((wdt)->reg_base + (field))
49 
50 #define wdt_write(wtd, field, val) \
51 	writel_relaxed((val), (wdt)->reg_base + (field))
52 
53 static int sama5d4_wdt_start(struct watchdog_device *wdd)
54 {
55 	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
56 
57 	wdt->mr &= ~AT91_WDT_WDDIS;
58 	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
59 
60 	return 0;
61 }
62 
63 static int sama5d4_wdt_stop(struct watchdog_device *wdd)
64 {
65 	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
66 
67 	wdt->mr |= AT91_WDT_WDDIS;
68 	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
69 
70 	return 0;
71 }
72 
73 static int sama5d4_wdt_ping(struct watchdog_device *wdd)
74 {
75 	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
76 
77 	wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
78 
79 	return 0;
80 }
81 
82 static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
83 				 unsigned int timeout)
84 {
85 	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
86 	u32 value = WDT_SEC2TICKS(timeout);
87 
88 	wdt->mr &= ~AT91_WDT_WDV;
89 	wdt->mr &= ~AT91_WDT_WDD;
90 	wdt->mr |= AT91_WDT_SET_WDV(value);
91 	wdt->mr |= AT91_WDT_SET_WDD(value);
92 	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
93 
94 	wdd->timeout = timeout;
95 
96 	return 0;
97 }
98 
99 static const struct watchdog_info sama5d4_wdt_info = {
100 	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
101 	.identity = "Atmel SAMA5D4 Watchdog",
102 };
103 
104 static const struct watchdog_ops sama5d4_wdt_ops = {
105 	.owner = THIS_MODULE,
106 	.start = sama5d4_wdt_start,
107 	.stop = sama5d4_wdt_stop,
108 	.ping = sama5d4_wdt_ping,
109 	.set_timeout = sama5d4_wdt_set_timeout,
110 };
111 
112 static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
113 {
114 	struct sama5d4_wdt *wdt = platform_get_drvdata(dev_id);
115 
116 	if (wdt_read(wdt, AT91_WDT_SR)) {
117 		pr_crit("Atmel Watchdog Software Reset\n");
118 		emergency_restart();
119 		pr_crit("Reboot didn't succeed\n");
120 	}
121 
122 	return IRQ_HANDLED;
123 }
124 
125 static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
126 {
127 	const char *tmp;
128 
129 	wdt->mr = AT91_WDT_WDDIS;
130 
131 	if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
132 	    !strcmp(tmp, "software"))
133 		wdt->mr |= AT91_WDT_WDFIEN;
134 	else
135 		wdt->mr |= AT91_WDT_WDRSTEN;
136 
137 	if (of_property_read_bool(np, "atmel,idle-halt"))
138 		wdt->mr |= AT91_WDT_WDIDLEHLT;
139 
140 	if (of_property_read_bool(np, "atmel,dbg-halt"))
141 		wdt->mr |= AT91_WDT_WDDBGHLT;
142 
143 	return 0;
144 }
145 
146 static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
147 {
148 	struct watchdog_device *wdd = &wdt->wdd;
149 	u32 value = WDT_SEC2TICKS(wdd->timeout);
150 	u32 reg;
151 
152 	/*
153 	 * Because the fields WDV and WDD must not be modified when the WDDIS
154 	 * bit is set, so clear the WDDIS bit before writing the WDT_MR.
155 	 */
156 	reg = wdt_read(wdt, AT91_WDT_MR);
157 	reg &= ~AT91_WDT_WDDIS;
158 	wdt_write(wdt, AT91_WDT_MR, reg);
159 
160 	wdt->mr |= AT91_WDT_SET_WDD(value);
161 	wdt->mr |= AT91_WDT_SET_WDV(value);
162 
163 	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
164 
165 	return 0;
166 }
167 
168 static int sama5d4_wdt_probe(struct platform_device *pdev)
169 {
170 	struct watchdog_device *wdd;
171 	struct sama5d4_wdt *wdt;
172 	struct resource *res;
173 	void __iomem *regs;
174 	u32 irq = 0;
175 	int ret;
176 
177 	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
178 	if (!wdt)
179 		return -ENOMEM;
180 
181 	wdd = &wdt->wdd;
182 	wdd->timeout = wdt_timeout;
183 	wdd->info = &sama5d4_wdt_info;
184 	wdd->ops = &sama5d4_wdt_ops;
185 	wdd->min_timeout = MIN_WDT_TIMEOUT;
186 	wdd->max_timeout = MAX_WDT_TIMEOUT;
187 
188 	watchdog_set_drvdata(wdd, wdt);
189 
190 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
191 	regs = devm_ioremap_resource(&pdev->dev, res);
192 	if (IS_ERR(regs))
193 		return PTR_ERR(regs);
194 
195 	wdt->reg_base = regs;
196 
197 	if (pdev->dev.of_node) {
198 		irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
199 		if (!irq)
200 			dev_warn(&pdev->dev, "failed to get IRQ from DT\n");
201 
202 		ret = of_sama5d4_wdt_init(pdev->dev.of_node, wdt);
203 		if (ret)
204 			return ret;
205 	}
206 
207 	if ((wdt->mr & AT91_WDT_WDFIEN) && irq) {
208 		ret = devm_request_irq(&pdev->dev, irq, sama5d4_wdt_irq_handler,
209 				       IRQF_SHARED | IRQF_IRQPOLL |
210 				       IRQF_NO_SUSPEND, pdev->name, pdev);
211 		if (ret) {
212 			dev_err(&pdev->dev,
213 				"cannot register interrupt handler\n");
214 			return ret;
215 		}
216 	}
217 
218 	ret = watchdog_init_timeout(wdd, wdt_timeout, &pdev->dev);
219 	if (ret) {
220 		dev_err(&pdev->dev, "unable to set timeout value\n");
221 		return ret;
222 	}
223 
224 	ret = sama5d4_wdt_init(wdt);
225 	if (ret)
226 		return ret;
227 
228 	watchdog_set_nowayout(wdd, nowayout);
229 
230 	ret = watchdog_register_device(wdd);
231 	if (ret) {
232 		dev_err(&pdev->dev, "failed to register watchdog device\n");
233 		return ret;
234 	}
235 
236 	platform_set_drvdata(pdev, wdt);
237 
238 	dev_info(&pdev->dev, "initialized (timeout = %d sec, nowayout = %d)\n",
239 		 wdt_timeout, nowayout);
240 
241 	return 0;
242 }
243 
244 static int sama5d4_wdt_remove(struct platform_device *pdev)
245 {
246 	struct sama5d4_wdt *wdt = platform_get_drvdata(pdev);
247 
248 	sama5d4_wdt_stop(&wdt->wdd);
249 
250 	watchdog_unregister_device(&wdt->wdd);
251 
252 	return 0;
253 }
254 
255 static const struct of_device_id sama5d4_wdt_of_match[] = {
256 	{ .compatible = "atmel,sama5d4-wdt", },
257 	{ }
258 };
259 MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
260 
261 #ifdef CONFIG_PM_SLEEP
262 static int sama5d4_wdt_resume(struct device *dev)
263 {
264 	struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
265 
266 	wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
267 	if (wdt->mr & AT91_WDT_WDDIS)
268 		wdt_write(wdt, AT91_WDT_MR, wdt->mr);
269 
270 	return 0;
271 }
272 #endif
273 
274 static SIMPLE_DEV_PM_OPS(sama5d4_wdt_pm_ops, NULL,
275 			 sama5d4_wdt_resume);
276 
277 static struct platform_driver sama5d4_wdt_driver = {
278 	.probe		= sama5d4_wdt_probe,
279 	.remove		= sama5d4_wdt_remove,
280 	.driver		= {
281 		.name	= "sama5d4_wdt",
282 		.pm	= &sama5d4_wdt_pm_ops,
283 		.of_match_table = sama5d4_wdt_of_match,
284 	}
285 };
286 module_platform_driver(sama5d4_wdt_driver);
287 
288 MODULE_AUTHOR("Atmel Corporation");
289 MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
290 MODULE_LICENSE("GPL v2");
291