xref: /linux/drivers/watchdog/geodewdt.c (revision 3932b9ca55b0be314a36d3e84faff3e823c081f5) 
1 /* Watchdog timer for machines with the CS5535/CS5536 companion chip
2  *
3  * Copyright (C) 2006-2007, Advanced Micro Devices, Inc.
4  * Copyright (C) 2009  Andres Salomon <dilinger@collabora.co.uk>
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11 
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 
14 #include <linux/module.h>
15 #include <linux/moduleparam.h>
16 #include <linux/types.h>
17 #include <linux/miscdevice.h>
18 #include <linux/watchdog.h>
19 #include <linux/fs.h>
20 #include <linux/platform_device.h>
21 #include <linux/reboot.h>
22 #include <linux/uaccess.h>
23 
24 #include <linux/cs5535.h>
25 
26 #define GEODEWDT_HZ 500
27 #define GEODEWDT_SCALE 6
28 #define GEODEWDT_MAX_SECONDS 131
29 
30 #define WDT_FLAGS_OPEN 1
31 #define WDT_FLAGS_ORPHAN 2
32 
33 #define DRV_NAME "geodewdt"
34 #define WATCHDOG_NAME "Geode GX/LX WDT"
35 #define WATCHDOG_TIMEOUT 60
36 
37 static int timeout = WATCHDOG_TIMEOUT;
38 module_param(timeout, int, 0);
39 MODULE_PARM_DESC(timeout,
40 	"Watchdog timeout in seconds. 1<= timeout <=131, default="
41 				__MODULE_STRING(WATCHDOG_TIMEOUT) ".");
42 
43 static bool nowayout = WATCHDOG_NOWAYOUT;
44 module_param(nowayout, bool, 0);
45 MODULE_PARM_DESC(nowayout,
46 	"Watchdog cannot be stopped once started (default="
47 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
48 
49 static struct platform_device *geodewdt_platform_device;
50 static unsigned long wdt_flags;
51 static struct cs5535_mfgpt_timer *wdt_timer;
52 static int safe_close;
53 
54 static void geodewdt_ping(void)
55 {
56 	/* Stop the counter */
57 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
58 
59 	/* Reset the counter */
60 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
61 
62 	/* Enable the counter */
63 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
64 }
65 
66 static void geodewdt_disable(void)
67 {
68 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
69 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
70 }
71 
72 static int geodewdt_set_heartbeat(int val)
73 {
74 	if (val < 1 || val > GEODEWDT_MAX_SECONDS)
75 		return -EINVAL;
76 
77 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
78 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, val * GEODEWDT_HZ);
79 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
80 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
81 
82 	timeout = val;
83 	return 0;
84 }
85 
86 static int geodewdt_open(struct inode *inode, struct file *file)
87 {
88 	if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags))
89 		return -EBUSY;
90 
91 	if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags))
92 		__module_get(THIS_MODULE);
93 
94 	geodewdt_ping();
95 	return nonseekable_open(inode, file);
96 }
97 
98 static int geodewdt_release(struct inode *inode, struct file *file)
99 {
100 	if (safe_close) {
101 		geodewdt_disable();
102 		module_put(THIS_MODULE);
103 	} else {
104 		pr_crit("Unexpected close - watchdog is not stopping\n");
105 		geodewdt_ping();
106 
107 		set_bit(WDT_FLAGS_ORPHAN, &wdt_flags);
108 	}
109 
110 	clear_bit(WDT_FLAGS_OPEN, &wdt_flags);
111 	safe_close = 0;
112 	return 0;
113 }
114 
115 static ssize_t geodewdt_write(struct file *file, const char __user *data,
116 				size_t len, loff_t *ppos)
117 {
118 	if (len) {
119 		if (!nowayout) {
120 			size_t i;
121 			safe_close = 0;
122 
123 			for (i = 0; i != len; i++) {
124 				char c;
125 
126 				if (get_user(c, data + i))
127 					return -EFAULT;
128 
129 				if (c == 'V')
130 					safe_close = 1;
131 			}
132 		}
133 
134 		geodewdt_ping();
135 	}
136 	return len;
137 }
138 
139 static long geodewdt_ioctl(struct file *file, unsigned int cmd,
140 				unsigned long arg)
141 {
142 	void __user *argp = (void __user *)arg;
143 	int __user *p = argp;
144 	int interval;
145 
146 	static const struct watchdog_info ident = {
147 		.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING
148 		| WDIOF_MAGICCLOSE,
149 		.firmware_version =     1,
150 		.identity =             WATCHDOG_NAME,
151 	};
152 
153 	switch (cmd) {
154 	case WDIOC_GETSUPPORT:
155 		return copy_to_user(argp, &ident,
156 				    sizeof(ident)) ? -EFAULT : 0;
157 		break;
158 
159 	case WDIOC_GETSTATUS:
160 	case WDIOC_GETBOOTSTATUS:
161 		return put_user(0, p);
162 
163 	case WDIOC_SETOPTIONS:
164 	{
165 		int options, ret = -EINVAL;
166 
167 		if (get_user(options, p))
168 			return -EFAULT;
169 
170 		if (options & WDIOS_DISABLECARD) {
171 			geodewdt_disable();
172 			ret = 0;
173 		}
174 
175 		if (options & WDIOS_ENABLECARD) {
176 			geodewdt_ping();
177 			ret = 0;
178 		}
179 
180 		return ret;
181 	}
182 	case WDIOC_KEEPALIVE:
183 		geodewdt_ping();
184 		return 0;
185 
186 	case WDIOC_SETTIMEOUT:
187 		if (get_user(interval, p))
188 			return -EFAULT;
189 
190 		if (geodewdt_set_heartbeat(interval))
191 			return -EINVAL;
192 	/* Fall through */
193 	case WDIOC_GETTIMEOUT:
194 		return put_user(timeout, p);
195 
196 	default:
197 		return -ENOTTY;
198 	}
199 
200 	return 0;
201 }
202 
203 static const struct file_operations geodewdt_fops = {
204 	.owner          = THIS_MODULE,
205 	.llseek         = no_llseek,
206 	.write          = geodewdt_write,
207 	.unlocked_ioctl = geodewdt_ioctl,
208 	.open           = geodewdt_open,
209 	.release        = geodewdt_release,
210 };
211 
212 static struct miscdevice geodewdt_miscdev = {
213 	.minor = WATCHDOG_MINOR,
214 	.name = "watchdog",
215 	.fops = &geodewdt_fops,
216 };
217 
218 static int __init geodewdt_probe(struct platform_device *dev)
219 {
220 	int ret;
221 
222 	wdt_timer = cs5535_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);
223 	if (!wdt_timer) {
224 		pr_err("No timers were available\n");
225 		return -ENODEV;
226 	}
227 
228 	/* Set up the timer */
229 
230 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP,
231 			  GEODEWDT_SCALE | (3 << 8));
232 
233 	/* Set up comparator 2 to reset when the event fires */
234 	cs5535_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1);
235 
236 	/* Set up the initial timeout */
237 
238 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2,
239 		timeout * GEODEWDT_HZ);
240 
241 	ret = misc_register(&geodewdt_miscdev);
242 
243 	return ret;
244 }
245 
246 static int geodewdt_remove(struct platform_device *dev)
247 {
248 	misc_deregister(&geodewdt_miscdev);
249 	return 0;
250 }
251 
252 static void geodewdt_shutdown(struct platform_device *dev)
253 {
254 	geodewdt_disable();
255 }
256 
257 static struct platform_driver geodewdt_driver = {
258 	.remove		= geodewdt_remove,
259 	.shutdown	= geodewdt_shutdown,
260 	.driver		= {
261 		.owner	= THIS_MODULE,
262 		.name	= DRV_NAME,
263 	},
264 };
265 
266 static int __init geodewdt_init(void)
267 {
268 	int ret;
269 
270 	geodewdt_platform_device = platform_device_register_simple(DRV_NAME,
271 								-1, NULL, 0);
272 	if (IS_ERR(geodewdt_platform_device))
273 		return PTR_ERR(geodewdt_platform_device);
274 
275 	ret = platform_driver_probe(&geodewdt_driver, geodewdt_probe);
276 	if (ret)
277 		goto err;
278 
279 	return 0;
280 err:
281 	platform_device_unregister(geodewdt_platform_device);
282 	return ret;
283 }
284 
285 static void __exit geodewdt_exit(void)
286 {
287 	platform_device_unregister(geodewdt_platform_device);
288 	platform_driver_unregister(&geodewdt_driver);
289 }
290 
291 module_init(geodewdt_init);
292 module_exit(geodewdt_exit);
293 
294 MODULE_AUTHOR("Advanced Micro Devices, Inc");
295 MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver");
296 MODULE_LICENSE("GPL");
297