1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * drivers/char/watchdog/max63xx_wdt.c
4  *
5  * Driver for max63{69,70,71,72,73,74} watchdog timers
6  *
7  * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org>
8  *
9  * This driver assumes the watchdog pins are memory mapped (as it is
10  * the case for the Arcom Zeus). Should it be connected over GPIOs or
11  * another interface, some abstraction will have to be introduced.
12  */
13 
14 #include <linux/err.h>
15 #include <linux/module.h>
16 #include <linux/moduleparam.h>
17 #include <linux/mod_devicetable.h>
18 #include <linux/types.h>
19 #include <linux/kernel.h>
20 #include <linux/watchdog.h>
21 #include <linux/bitops.h>
22 #include <linux/platform_device.h>
23 #include <linux/spinlock.h>
24 #include <linux/io.h>
25 #include <linux/slab.h>
26 #include <linux/property.h>
27 
28 #define DEFAULT_HEARTBEAT 60
29 #define MAX_HEARTBEAT     60
30 
31 static unsigned int heartbeat = DEFAULT_HEARTBEAT;
32 static bool nowayout  = WATCHDOG_NOWAYOUT;
33 
34 /*
35  * Memory mapping: a single byte, 3 first lower bits to select bit 3
36  * to ping the watchdog.
37  */
38 #define MAX6369_WDSET	(7 << 0)
39 #define MAX6369_WDI	(1 << 3)
40 
41 #define MAX6369_WDSET_DISABLED	3
42 
43 static int nodelay;
44 
45 struct max63xx_wdt {
46 	struct watchdog_device wdd;
47 	const struct max63xx_timeout *timeout;
48 
49 	/* memory mapping */
50 	void __iomem *base;
51 	spinlock_t lock;
52 
53 	/* WDI and WSET bits write access routines */
54 	void (*ping)(struct max63xx_wdt *wdt);
55 	void (*set)(struct max63xx_wdt *wdt, u8 set);
56 };
57 
58 /*
59  * The timeout values used are actually the absolute minimum the chip
60  * offers. Typical values on my board are slightly over twice as long
61  * (10s setting ends up with a 25s timeout), and can be up to 3 times
62  * the nominal setting (according to the datasheet). So please take
63  * these values with a grain of salt. Same goes for the initial delay
64  * "feature". Only max6373/74 have a few settings without this initial
65  * delay (selected with the "nodelay" parameter).
66  *
67  * I also decided to remove from the tables any timeout smaller than a
68  * second, as it looked completly overkill...
69  */
70 
71 /* Timeouts in second */
72 struct max63xx_timeout {
73 	const u8 wdset;
74 	const u8 tdelay;
75 	const u8 twd;
76 };
77 
78 static const struct max63xx_timeout max6369_table[] = {
79 	{ 5,  1,  1 },
80 	{ 6, 10, 10 },
81 	{ 7, 60, 60 },
82 	{ },
83 };
84 
85 static const struct max63xx_timeout max6371_table[] = {
86 	{ 6, 60,  3 },
87 	{ 7, 60, 60 },
88 	{ },
89 };
90 
91 static const struct max63xx_timeout max6373_table[] = {
92 	{ 2, 60,  1 },
93 	{ 5,  0,  1 },
94 	{ 1,  3,  3 },
95 	{ 7, 60, 10 },
96 	{ 6,  0, 10 },
97 	{ },
98 };
99 
100 static const struct max63xx_timeout *
101 max63xx_select_timeout(const struct max63xx_timeout *table, int value)
102 {
103 	while (table->twd) {
104 		if (value <= table->twd) {
105 			if (nodelay && table->tdelay == 0)
106 				return table;
107 
108 			if (!nodelay)
109 				return table;
110 		}
111 
112 		table++;
113 	}
114 
115 	return NULL;
116 }
117 
118 static int max63xx_wdt_ping(struct watchdog_device *wdd)
119 {
120 	struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
121 
122 	wdt->ping(wdt);
123 	return 0;
124 }
125 
126 static int max63xx_wdt_start(struct watchdog_device *wdd)
127 {
128 	struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
129 
130 	wdt->set(wdt, wdt->timeout->wdset);
131 
132 	/* check for a edge triggered startup */
133 	if (wdt->timeout->tdelay == 0)
134 		wdt->ping(wdt);
135 	return 0;
136 }
137 
138 static int max63xx_wdt_stop(struct watchdog_device *wdd)
139 {
140 	struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
141 
142 	wdt->set(wdt, MAX6369_WDSET_DISABLED);
143 	return 0;
144 }
145 
146 static const struct watchdog_ops max63xx_wdt_ops = {
147 	.owner = THIS_MODULE,
148 	.start = max63xx_wdt_start,
149 	.stop = max63xx_wdt_stop,
150 	.ping = max63xx_wdt_ping,
151 };
152 
153 static const struct watchdog_info max63xx_wdt_info = {
154 	.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
155 	.identity = "max63xx Watchdog",
156 };
157 
158 static void max63xx_mmap_ping(struct max63xx_wdt *wdt)
159 {
160 	u8 val;
161 
162 	spin_lock(&wdt->lock);
163 
164 	val = __raw_readb(wdt->base);
165 
166 	__raw_writeb(val | MAX6369_WDI, wdt->base);
167 	__raw_writeb(val & ~MAX6369_WDI, wdt->base);
168 
169 	spin_unlock(&wdt->lock);
170 }
171 
172 static void max63xx_mmap_set(struct max63xx_wdt *wdt, u8 set)
173 {
174 	u8 val;
175 
176 	spin_lock(&wdt->lock);
177 
178 	val = __raw_readb(wdt->base);
179 	val &= ~MAX6369_WDSET;
180 	val |= set & MAX6369_WDSET;
181 	__raw_writeb(val, wdt->base);
182 
183 	spin_unlock(&wdt->lock);
184 }
185 
186 static int max63xx_mmap_init(struct platform_device *p, struct max63xx_wdt *wdt)
187 {
188 	wdt->base = devm_platform_ioremap_resource(p, 0);
189 	if (IS_ERR(wdt->base))
190 		return PTR_ERR(wdt->base);
191 
192 	spin_lock_init(&wdt->lock);
193 
194 	wdt->ping = max63xx_mmap_ping;
195 	wdt->set = max63xx_mmap_set;
196 	return 0;
197 }
198 
199 static int max63xx_wdt_probe(struct platform_device *pdev)
200 {
201 	struct device *dev = &pdev->dev;
202 	struct max63xx_wdt *wdt;
203 	const struct max63xx_timeout *table;
204 	int err;
205 
206 	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
207 	if (!wdt)
208 		return -ENOMEM;
209 
210 	/* Attempt to use fwnode first */
211 	table = device_get_match_data(dev);
212 	if (!table)
213 		table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
214 
215 	if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
216 		heartbeat = DEFAULT_HEARTBEAT;
217 
218 	wdt->timeout = max63xx_select_timeout(table, heartbeat);
219 	if (!wdt->timeout) {
220 		dev_err(dev, "unable to satisfy %ds heartbeat request\n",
221 			heartbeat);
222 		return -EINVAL;
223 	}
224 
225 	err = max63xx_mmap_init(pdev, wdt);
226 	if (err)
227 		return err;
228 
229 	platform_set_drvdata(pdev, &wdt->wdd);
230 	watchdog_set_drvdata(&wdt->wdd, wdt);
231 
232 	wdt->wdd.parent = dev;
233 	wdt->wdd.timeout = wdt->timeout->twd;
234 	wdt->wdd.info = &max63xx_wdt_info;
235 	wdt->wdd.ops = &max63xx_wdt_ops;
236 
237 	watchdog_set_nowayout(&wdt->wdd, nowayout);
238 
239 	err = devm_watchdog_register_device(dev, &wdt->wdd);
240 	if (err)
241 		return err;
242 
243 	dev_info(dev, "using %ds heartbeat with %ds initial delay\n",
244 		 wdt->timeout->twd, wdt->timeout->tdelay);
245 	return 0;
246 }
247 
248 static const struct platform_device_id max63xx_id_table[] = {
249 	{ "max6369_wdt", (kernel_ulong_t)max6369_table, },
250 	{ "max6370_wdt", (kernel_ulong_t)max6369_table, },
251 	{ "max6371_wdt", (kernel_ulong_t)max6371_table, },
252 	{ "max6372_wdt", (kernel_ulong_t)max6371_table, },
253 	{ "max6373_wdt", (kernel_ulong_t)max6373_table, },
254 	{ "max6374_wdt", (kernel_ulong_t)max6373_table, },
255 	{ },
256 };
257 MODULE_DEVICE_TABLE(platform, max63xx_id_table);
258 
259 static const struct of_device_id max63xx_dt_id_table[] = {
260 	{ .compatible = "maxim,max6369", .data = max6369_table, },
261 	{ .compatible = "maxim,max6370", .data = max6369_table, },
262 	{ .compatible = "maxim,max6371", .data = max6371_table, },
263 	{ .compatible = "maxim,max6372", .data = max6371_table, },
264 	{ .compatible = "maxim,max6373", .data = max6373_table, },
265 	{ .compatible = "maxim,max6374", .data = max6373_table, },
266 	{ }
267 };
268 MODULE_DEVICE_TABLE(of, max63xx_dt_id_table);
269 
270 static struct platform_driver max63xx_wdt_driver = {
271 	.probe		= max63xx_wdt_probe,
272 	.id_table	= max63xx_id_table,
273 	.driver		= {
274 		.name	= "max63xx_wdt",
275 		.of_match_table = max63xx_dt_id_table,
276 	},
277 };
278 
279 module_platform_driver(max63xx_wdt_driver);
280 
281 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
282 MODULE_DESCRIPTION("max63xx Watchdog Driver");
283 
284 module_param(heartbeat, int, 0);
285 MODULE_PARM_DESC(heartbeat,
286 		 "Watchdog heartbeat period in seconds from 1 to "
287 		 __MODULE_STRING(MAX_HEARTBEAT) ", default "
288 		 __MODULE_STRING(DEFAULT_HEARTBEAT));
289 
290 module_param(nowayout, bool, 0);
291 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
292 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
293 
294 module_param(nodelay, int, 0);
295 MODULE_PARM_DESC(nodelay,
296 		 "Force selection of a timeout setting without initial delay "
297 		 "(max6373/74 only, default=0)");
298 
299 MODULE_LICENSE("GPL v2");
300