1 /*
2  * drivers/char/watchdog/max63xx_wdt.c
3  *
4  * Driver for max63{69,70,71,72,73,74} watchdog timers
5  *
6  * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org>
7  *
8  * This file is licensed under the terms of the GNU General Public
9  * License version 2. This program is licensed "as is" without any
10  * warranty of any kind, whether express or implied.
11  *
12  * This driver assumes the watchdog pins are memory mapped (as it is
13  * the case for the Arcom Zeus). Should it be connected over GPIOs or
14  * another interface, some abstraction will have to be introduced.
15  */
16 
17 #include <linux/err.h>
18 #include <linux/module.h>
19 #include <linux/moduleparam.h>
20 #include <linux/mod_devicetable.h>
21 #include <linux/types.h>
22 #include <linux/kernel.h>
23 #include <linux/watchdog.h>
24 #include <linux/bitops.h>
25 #include <linux/platform_device.h>
26 #include <linux/spinlock.h>
27 #include <linux/io.h>
28 #include <linux/slab.h>
29 #include <linux/property.h>
30 
31 #define DEFAULT_HEARTBEAT 60
32 #define MAX_HEARTBEAT     60
33 
34 static unsigned int heartbeat = DEFAULT_HEARTBEAT;
35 static bool nowayout  = WATCHDOG_NOWAYOUT;
36 
37 /*
38  * Memory mapping: a single byte, 3 first lower bits to select bit 3
39  * to ping the watchdog.
40  */
41 #define MAX6369_WDSET	(7 << 0)
42 #define MAX6369_WDI	(1 << 3)
43 
44 #define MAX6369_WDSET_DISABLED	3
45 
46 static int nodelay;
47 
48 struct max63xx_wdt {
49 	struct watchdog_device wdd;
50 	const struct max63xx_timeout *timeout;
51 
52 	/* memory mapping */
53 	void __iomem *base;
54 	spinlock_t lock;
55 
56 	/* WDI and WSET bits write access routines */
57 	void (*ping)(struct max63xx_wdt *wdt);
58 	void (*set)(struct max63xx_wdt *wdt, u8 set);
59 };
60 
61 /*
62  * The timeout values used are actually the absolute minimum the chip
63  * offers. Typical values on my board are slightly over twice as long
64  * (10s setting ends up with a 25s timeout), and can be up to 3 times
65  * the nominal setting (according to the datasheet). So please take
66  * these values with a grain of salt. Same goes for the initial delay
67  * "feature". Only max6373/74 have a few settings without this initial
68  * delay (selected with the "nodelay" parameter).
69  *
70  * I also decided to remove from the tables any timeout smaller than a
71  * second, as it looked completly overkill...
72  */
73 
74 /* Timeouts in second */
75 struct max63xx_timeout {
76 	const u8 wdset;
77 	const u8 tdelay;
78 	const u8 twd;
79 };
80 
81 static const struct max63xx_timeout max6369_table[] = {
82 	{ 5,  1,  1 },
83 	{ 6, 10, 10 },
84 	{ 7, 60, 60 },
85 	{ },
86 };
87 
88 static const struct max63xx_timeout max6371_table[] = {
89 	{ 6, 60,  3 },
90 	{ 7, 60, 60 },
91 	{ },
92 };
93 
94 static const struct max63xx_timeout max6373_table[] = {
95 	{ 2, 60,  1 },
96 	{ 5,  0,  1 },
97 	{ 1,  3,  3 },
98 	{ 7, 60, 10 },
99 	{ 6,  0, 10 },
100 	{ },
101 };
102 
103 static const struct max63xx_timeout *
104 max63xx_select_timeout(const struct max63xx_timeout *table, int value)
105 {
106 	while (table->twd) {
107 		if (value <= table->twd) {
108 			if (nodelay && table->tdelay == 0)
109 				return table;
110 
111 			if (!nodelay)
112 				return table;
113 		}
114 
115 		table++;
116 	}
117 
118 	return NULL;
119 }
120 
121 static int max63xx_wdt_ping(struct watchdog_device *wdd)
122 {
123 	struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
124 
125 	wdt->ping(wdt);
126 	return 0;
127 }
128 
129 static int max63xx_wdt_start(struct watchdog_device *wdd)
130 {
131 	struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
132 
133 	wdt->set(wdt, wdt->timeout->wdset);
134 
135 	/* check for a edge triggered startup */
136 	if (wdt->timeout->tdelay == 0)
137 		wdt->ping(wdt);
138 	return 0;
139 }
140 
141 static int max63xx_wdt_stop(struct watchdog_device *wdd)
142 {
143 	struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
144 
145 	wdt->set(wdt, MAX6369_WDSET_DISABLED);
146 	return 0;
147 }
148 
149 static const struct watchdog_ops max63xx_wdt_ops = {
150 	.owner = THIS_MODULE,
151 	.start = max63xx_wdt_start,
152 	.stop = max63xx_wdt_stop,
153 	.ping = max63xx_wdt_ping,
154 };
155 
156 static const struct watchdog_info max63xx_wdt_info = {
157 	.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
158 	.identity = "max63xx Watchdog",
159 };
160 
161 static void max63xx_mmap_ping(struct max63xx_wdt *wdt)
162 {
163 	u8 val;
164 
165 	spin_lock(&wdt->lock);
166 
167 	val = __raw_readb(wdt->base);
168 
169 	__raw_writeb(val | MAX6369_WDI, wdt->base);
170 	__raw_writeb(val & ~MAX6369_WDI, wdt->base);
171 
172 	spin_unlock(&wdt->lock);
173 }
174 
175 static void max63xx_mmap_set(struct max63xx_wdt *wdt, u8 set)
176 {
177 	u8 val;
178 
179 	spin_lock(&wdt->lock);
180 
181 	val = __raw_readb(wdt->base);
182 	val &= ~MAX6369_WDSET;
183 	val |= set & MAX6369_WDSET;
184 	__raw_writeb(val, wdt->base);
185 
186 	spin_unlock(&wdt->lock);
187 }
188 
189 static int max63xx_mmap_init(struct platform_device *p, struct max63xx_wdt *wdt)
190 {
191 	wdt->base = devm_platform_ioremap_resource(p, 0);
192 	if (IS_ERR(wdt->base))
193 		return PTR_ERR(wdt->base);
194 
195 	spin_lock_init(&wdt->lock);
196 
197 	wdt->ping = max63xx_mmap_ping;
198 	wdt->set = max63xx_mmap_set;
199 	return 0;
200 }
201 
202 static int max63xx_wdt_probe(struct platform_device *pdev)
203 {
204 	struct device *dev = &pdev->dev;
205 	struct max63xx_wdt *wdt;
206 	const struct max63xx_timeout *table;
207 	int err;
208 
209 	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
210 	if (!wdt)
211 		return -ENOMEM;
212 
213 	/* Attempt to use fwnode first */
214 	table = device_get_match_data(dev);
215 	if (!table)
216 		table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
217 
218 	if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
219 		heartbeat = DEFAULT_HEARTBEAT;
220 
221 	wdt->timeout = max63xx_select_timeout(table, heartbeat);
222 	if (!wdt->timeout) {
223 		dev_err(dev, "unable to satisfy %ds heartbeat request\n",
224 			heartbeat);
225 		return -EINVAL;
226 	}
227 
228 	err = max63xx_mmap_init(pdev, wdt);
229 	if (err)
230 		return err;
231 
232 	platform_set_drvdata(pdev, &wdt->wdd);
233 	watchdog_set_drvdata(&wdt->wdd, wdt);
234 
235 	wdt->wdd.parent = dev;
236 	wdt->wdd.timeout = wdt->timeout->twd;
237 	wdt->wdd.info = &max63xx_wdt_info;
238 	wdt->wdd.ops = &max63xx_wdt_ops;
239 
240 	watchdog_set_nowayout(&wdt->wdd, nowayout);
241 
242 	err = devm_watchdog_register_device(dev, &wdt->wdd);
243 	if (err)
244 		return err;
245 
246 	dev_info(dev, "using %ds heartbeat with %ds initial delay\n",
247 		 wdt->timeout->twd, wdt->timeout->tdelay);
248 	return 0;
249 }
250 
251 static const struct platform_device_id max63xx_id_table[] = {
252 	{ "max6369_wdt", (kernel_ulong_t)max6369_table, },
253 	{ "max6370_wdt", (kernel_ulong_t)max6369_table, },
254 	{ "max6371_wdt", (kernel_ulong_t)max6371_table, },
255 	{ "max6372_wdt", (kernel_ulong_t)max6371_table, },
256 	{ "max6373_wdt", (kernel_ulong_t)max6373_table, },
257 	{ "max6374_wdt", (kernel_ulong_t)max6373_table, },
258 	{ },
259 };
260 MODULE_DEVICE_TABLE(platform, max63xx_id_table);
261 
262 static const struct of_device_id max63xx_dt_id_table[] = {
263 	{ .compatible = "maxim,max6369", .data = max6369_table, },
264 	{ .compatible = "maxim,max6370", .data = max6369_table, },
265 	{ .compatible = "maxim,max6371", .data = max6371_table, },
266 	{ .compatible = "maxim,max6372", .data = max6371_table, },
267 	{ .compatible = "maxim,max6373", .data = max6373_table, },
268 	{ .compatible = "maxim,max6374", .data = max6373_table, },
269 	{ }
270 };
271 MODULE_DEVICE_TABLE(of, max63xx_dt_id_table);
272 
273 static struct platform_driver max63xx_wdt_driver = {
274 	.probe		= max63xx_wdt_probe,
275 	.id_table	= max63xx_id_table,
276 	.driver		= {
277 		.name	= "max63xx_wdt",
278 		.of_match_table = max63xx_dt_id_table,
279 	},
280 };
281 
282 module_platform_driver(max63xx_wdt_driver);
283 
284 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
285 MODULE_DESCRIPTION("max63xx Watchdog Driver");
286 
287 module_param(heartbeat, int, 0);
288 MODULE_PARM_DESC(heartbeat,
289 		 "Watchdog heartbeat period in seconds from 1 to "
290 		 __MODULE_STRING(MAX_HEARTBEAT) ", default "
291 		 __MODULE_STRING(DEFAULT_HEARTBEAT));
292 
293 module_param(nowayout, bool, 0);
294 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
295 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
296 
297 module_param(nodelay, int, 0);
298 MODULE_PARM_DESC(nodelay,
299 		 "Force selection of a timeout setting without initial delay "
300 		 "(max6373/74 only, default=0)");
301 
302 MODULE_LICENSE("GPL v2");
303