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/types.h>
21 #include <linux/kernel.h>
22 #include <linux/miscdevice.h>
23 #include <linux/watchdog.h>
24 #include <linux/init.h>
25 #include <linux/bitops.h>
26 #include <linux/platform_device.h>
27 #include <linux/spinlock.h>
28 #include <linux/io.h>
29 #include <linux/slab.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 static DEFINE_SPINLOCK(io_lock);
45 
46 static int nodelay;
47 static void __iomem	*wdt_base;
48 
49 /*
50  * The timeout values used are actually the absolute minimum the chip
51  * offers. Typical values on my board are slightly over twice as long
52  * (10s setting ends up with a 25s timeout), and can be up to 3 times
53  * the nominal setting (according to the datasheet). So please take
54  * these values with a grain of salt. Same goes for the initial delay
55  * "feature". Only max6373/74 have a few settings without this initial
56  * delay (selected with the "nodelay" parameter).
57  *
58  * I also decided to remove from the tables any timeout smaller than a
59  * second, as it looked completly overkill...
60  */
61 
62 /* Timeouts in second */
63 struct max63xx_timeout {
64 	u8 wdset;
65 	u8 tdelay;
66 	u8 twd;
67 };
68 
69 static struct max63xx_timeout max6369_table[] = {
70 	{ 5,  1,  1 },
71 	{ 6, 10, 10 },
72 	{ 7, 60, 60 },
73 	{ },
74 };
75 
76 static struct max63xx_timeout max6371_table[] = {
77 	{ 6, 60,  3 },
78 	{ 7, 60, 60 },
79 	{ },
80 };
81 
82 static struct max63xx_timeout max6373_table[] = {
83 	{ 2, 60,  1 },
84 	{ 5,  0,  1 },
85 	{ 1,  3,  3 },
86 	{ 7, 60, 10 },
87 	{ 6,  0, 10 },
88 	{ },
89 };
90 
91 static struct max63xx_timeout *current_timeout;
92 
93 static struct max63xx_timeout *
94 max63xx_select_timeout(struct max63xx_timeout *table, int value)
95 {
96 	while (table->twd) {
97 		if (value <= table->twd) {
98 			if (nodelay && table->tdelay == 0)
99 				return table;
100 
101 			if (!nodelay)
102 				return table;
103 		}
104 
105 		table++;
106 	}
107 
108 	return NULL;
109 }
110 
111 static int max63xx_wdt_ping(struct watchdog_device *wdd)
112 {
113 	u8 val;
114 
115 	spin_lock(&io_lock);
116 
117 	val = __raw_readb(wdt_base);
118 
119 	__raw_writeb(val | MAX6369_WDI, wdt_base);
120 	__raw_writeb(val & ~MAX6369_WDI, wdt_base);
121 
122 	spin_unlock(&io_lock);
123 	return 0;
124 }
125 
126 static int max63xx_wdt_start(struct watchdog_device *wdd)
127 {
128 	struct max63xx_timeout *entry = watchdog_get_drvdata(wdd);
129 	u8 val;
130 
131 	spin_lock(&io_lock);
132 
133 	val = __raw_readb(wdt_base);
134 	val &= ~MAX6369_WDSET;
135 	val |= entry->wdset;
136 	__raw_writeb(val, wdt_base);
137 
138 	spin_unlock(&io_lock);
139 
140 	/* check for a edge triggered startup */
141 	if (entry->tdelay == 0)
142 		max63xx_wdt_ping(wdd);
143 	return 0;
144 }
145 
146 static int max63xx_wdt_stop(struct watchdog_device *wdd)
147 {
148 	u8 val;
149 
150 	spin_lock(&io_lock);
151 
152 	val = __raw_readb(wdt_base);
153 	val &= ~MAX6369_WDSET;
154 	val |= 3;
155 	__raw_writeb(val, wdt_base);
156 
157 	spin_unlock(&io_lock);
158 	return 0;
159 }
160 
161 static const struct watchdog_info max63xx_wdt_info = {
162 	.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
163 	.identity = "max63xx Watchdog",
164 };
165 
166 static const struct watchdog_ops max63xx_wdt_ops = {
167 	.owner = THIS_MODULE,
168 	.start = max63xx_wdt_start,
169 	.stop = max63xx_wdt_stop,
170 	.ping = max63xx_wdt_ping,
171 };
172 
173 static struct watchdog_device max63xx_wdt_dev = {
174 	.info = &max63xx_wdt_info,
175 	.ops = &max63xx_wdt_ops,
176 };
177 
178 static int max63xx_wdt_probe(struct platform_device *pdev)
179 {
180 	struct resource	*wdt_mem;
181 	struct max63xx_timeout *table;
182 
183 	table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
184 
185 	if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
186 		heartbeat = DEFAULT_HEARTBEAT;
187 
188 	dev_info(&pdev->dev, "requesting %ds heartbeat\n", heartbeat);
189 	current_timeout = max63xx_select_timeout(table, heartbeat);
190 
191 	if (!current_timeout) {
192 		dev_err(&pdev->dev, "unable to satisfy heartbeat request\n");
193 		return -EINVAL;
194 	}
195 
196 	dev_info(&pdev->dev, "using %ds heartbeat with %ds initial delay\n",
197 		 current_timeout->twd, current_timeout->tdelay);
198 
199 	heartbeat = current_timeout->twd;
200 
201 	wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
202 	wdt_base = devm_ioremap_resource(&pdev->dev, wdt_mem);
203 	if (IS_ERR(wdt_base))
204 		return PTR_ERR(wdt_base);
205 
206 	max63xx_wdt_dev.timeout = heartbeat;
207 	watchdog_set_nowayout(&max63xx_wdt_dev, nowayout);
208 	watchdog_set_drvdata(&max63xx_wdt_dev, current_timeout);
209 
210 	return watchdog_register_device(&max63xx_wdt_dev);
211 }
212 
213 static int max63xx_wdt_remove(struct platform_device *pdev)
214 {
215 	watchdog_unregister_device(&max63xx_wdt_dev);
216 	return 0;
217 }
218 
219 static struct platform_device_id max63xx_id_table[] = {
220 	{ "max6369_wdt", (kernel_ulong_t)max6369_table, },
221 	{ "max6370_wdt", (kernel_ulong_t)max6369_table, },
222 	{ "max6371_wdt", (kernel_ulong_t)max6371_table, },
223 	{ "max6372_wdt", (kernel_ulong_t)max6371_table, },
224 	{ "max6373_wdt", (kernel_ulong_t)max6373_table, },
225 	{ "max6374_wdt", (kernel_ulong_t)max6373_table, },
226 	{ },
227 };
228 MODULE_DEVICE_TABLE(platform, max63xx_id_table);
229 
230 static struct platform_driver max63xx_wdt_driver = {
231 	.probe		= max63xx_wdt_probe,
232 	.remove		= max63xx_wdt_remove,
233 	.id_table	= max63xx_id_table,
234 	.driver		= {
235 		.name	= "max63xx_wdt",
236 		.owner	= THIS_MODULE,
237 	},
238 };
239 
240 module_platform_driver(max63xx_wdt_driver);
241 
242 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
243 MODULE_DESCRIPTION("max63xx Watchdog Driver");
244 
245 module_param(heartbeat, int, 0);
246 MODULE_PARM_DESC(heartbeat,
247 		 "Watchdog heartbeat period in seconds from 1 to "
248 		 __MODULE_STRING(MAX_HEARTBEAT) ", default "
249 		 __MODULE_STRING(DEFAULT_HEARTBEAT));
250 
251 module_param(nowayout, bool, 0);
252 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
253 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
254 
255 module_param(nodelay, int, 0);
256 MODULE_PARM_DESC(nodelay,
257 		 "Force selection of a timeout setting without initial delay "
258 		 "(max6373/74 only, default=0)");
259 
260 MODULE_LICENSE("GPL");
261 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
262