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