xref: /linux/drivers/watchdog/geodewdt.c (revision c532de5a67a70f8533d495f8f2aaa9a0491c3ad0) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Watchdog timer for machines with the CS5535/CS5536 companion chip
3  *
4  * Copyright (C) 2006-2007, Advanced Micro Devices, Inc.
5  * Copyright (C) 2009  Andres Salomon <dilinger@collabora.co.uk>
6  */
7 
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 
10 #include <linux/module.h>
11 #include <linux/moduleparam.h>
12 #include <linux/types.h>
13 #include <linux/miscdevice.h>
14 #include <linux/watchdog.h>
15 #include <linux/fs.h>
16 #include <linux/platform_device.h>
17 #include <linux/reboot.h>
18 #include <linux/uaccess.h>
19 
20 #include <linux/cs5535.h>
21 
22 #define GEODEWDT_HZ 500
23 #define GEODEWDT_SCALE 6
24 #define GEODEWDT_MAX_SECONDS 131
25 
26 #define WDT_FLAGS_OPEN 1
27 #define WDT_FLAGS_ORPHAN 2
28 
29 #define DRV_NAME "geodewdt"
30 #define WATCHDOG_NAME "Geode GX/LX WDT"
31 #define WATCHDOG_TIMEOUT 60
32 
33 static int timeout = WATCHDOG_TIMEOUT;
34 module_param(timeout, int, 0);
35 MODULE_PARM_DESC(timeout,
36 	"Watchdog timeout in seconds. 1<= timeout <=131, default="
37 				__MODULE_STRING(WATCHDOG_TIMEOUT) ".");
38 
39 static bool nowayout = WATCHDOG_NOWAYOUT;
40 module_param(nowayout, bool, 0);
41 MODULE_PARM_DESC(nowayout,
42 	"Watchdog cannot be stopped once started (default="
43 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
44 
45 static struct platform_device *geodewdt_platform_device;
46 static unsigned long wdt_flags;
47 static struct cs5535_mfgpt_timer *wdt_timer;
48 static int safe_close;
49 
50 static void geodewdt_ping(void)
51 {
52 	/* Stop the counter */
53 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
54 
55 	/* Reset the counter */
56 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
57 
58 	/* Enable the counter */
59 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
60 }
61 
62 static void geodewdt_disable(void)
63 {
64 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
65 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
66 }
67 
68 static int geodewdt_set_heartbeat(int val)
69 {
70 	if (val < 1 || val > GEODEWDT_MAX_SECONDS)
71 		return -EINVAL;
72 
73 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
74 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, val * GEODEWDT_HZ);
75 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
76 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
77 
78 	timeout = val;
79 	return 0;
80 }
81 
82 static int geodewdt_open(struct inode *inode, struct file *file)
83 {
84 	if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags))
85 		return -EBUSY;
86 
87 	if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags))
88 		__module_get(THIS_MODULE);
89 
90 	geodewdt_ping();
91 	return stream_open(inode, file);
92 }
93 
94 static int geodewdt_release(struct inode *inode, struct file *file)
95 {
96 	if (safe_close) {
97 		geodewdt_disable();
98 		module_put(THIS_MODULE);
99 	} else {
100 		pr_crit("Unexpected close - watchdog is not stopping\n");
101 		geodewdt_ping();
102 
103 		set_bit(WDT_FLAGS_ORPHAN, &wdt_flags);
104 	}
105 
106 	clear_bit(WDT_FLAGS_OPEN, &wdt_flags);
107 	safe_close = 0;
108 	return 0;
109 }
110 
111 static ssize_t geodewdt_write(struct file *file, const char __user *data,
112 				size_t len, loff_t *ppos)
113 {
114 	if (len) {
115 		if (!nowayout) {
116 			size_t i;
117 			safe_close = 0;
118 
119 			for (i = 0; i != len; i++) {
120 				char c;
121 
122 				if (get_user(c, data + i))
123 					return -EFAULT;
124 
125 				if (c == 'V')
126 					safe_close = 1;
127 			}
128 		}
129 
130 		geodewdt_ping();
131 	}
132 	return len;
133 }
134 
135 static long geodewdt_ioctl(struct file *file, unsigned int cmd,
136 				unsigned long arg)
137 {
138 	void __user *argp = (void __user *)arg;
139 	int __user *p = argp;
140 	int interval;
141 
142 	static const struct watchdog_info ident = {
143 		.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING
144 		| WDIOF_MAGICCLOSE,
145 		.firmware_version =     1,
146 		.identity =             WATCHDOG_NAME,
147 	};
148 
149 	switch (cmd) {
150 	case WDIOC_GETSUPPORT:
151 		return copy_to_user(argp, &ident,
152 				    sizeof(ident)) ? -EFAULT : 0;
153 	case WDIOC_GETSTATUS:
154 	case WDIOC_GETBOOTSTATUS:
155 		return put_user(0, p);
156 
157 	case WDIOC_SETOPTIONS:
158 	{
159 		int options, ret = -EINVAL;
160 
161 		if (get_user(options, p))
162 			return -EFAULT;
163 
164 		if (options & WDIOS_DISABLECARD) {
165 			geodewdt_disable();
166 			ret = 0;
167 		}
168 
169 		if (options & WDIOS_ENABLECARD) {
170 			geodewdt_ping();
171 			ret = 0;
172 		}
173 
174 		return ret;
175 	}
176 	case WDIOC_KEEPALIVE:
177 		geodewdt_ping();
178 		return 0;
179 
180 	case WDIOC_SETTIMEOUT:
181 		if (get_user(interval, p))
182 			return -EFAULT;
183 
184 		if (geodewdt_set_heartbeat(interval))
185 			return -EINVAL;
186 		fallthrough;
187 	case WDIOC_GETTIMEOUT:
188 		return put_user(timeout, p);
189 
190 	default:
191 		return -ENOTTY;
192 	}
193 
194 	return 0;
195 }
196 
197 static const struct file_operations geodewdt_fops = {
198 	.owner          = THIS_MODULE,
199 	.write          = geodewdt_write,
200 	.unlocked_ioctl = geodewdt_ioctl,
201 	.compat_ioctl	= compat_ptr_ioctl,
202 	.open           = geodewdt_open,
203 	.release        = geodewdt_release,
204 };
205 
206 static struct miscdevice geodewdt_miscdev = {
207 	.minor = WATCHDOG_MINOR,
208 	.name = "watchdog",
209 	.fops = &geodewdt_fops,
210 };
211 
212 static int __init geodewdt_probe(struct platform_device *dev)
213 {
214 	int ret;
215 
216 	wdt_timer = cs5535_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);
217 	if (!wdt_timer) {
218 		pr_err("No timers were available\n");
219 		return -ENODEV;
220 	}
221 
222 	/* Set up the timer */
223 
224 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP,
225 			  GEODEWDT_SCALE | (3 << 8));
226 
227 	/* Set up comparator 2 to reset when the event fires */
228 	cs5535_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1);
229 
230 	/* Set up the initial timeout */
231 
232 	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2,
233 		timeout * GEODEWDT_HZ);
234 
235 	ret = misc_register(&geodewdt_miscdev);
236 
237 	return ret;
238 }
239 
240 static void geodewdt_remove(struct platform_device *dev)
241 {
242 	misc_deregister(&geodewdt_miscdev);
243 }
244 
245 static void geodewdt_shutdown(struct platform_device *dev)
246 {
247 	geodewdt_disable();
248 }
249 
250 static struct platform_driver geodewdt_driver = {
251 	.remove_new	= geodewdt_remove,
252 	.shutdown	= geodewdt_shutdown,
253 	.driver		= {
254 		.name	= DRV_NAME,
255 	},
256 };
257 
258 static int __init geodewdt_init(void)
259 {
260 	int ret;
261 
262 	geodewdt_platform_device = platform_device_register_simple(DRV_NAME,
263 								-1, NULL, 0);
264 	if (IS_ERR(geodewdt_platform_device))
265 		return PTR_ERR(geodewdt_platform_device);
266 
267 	ret = platform_driver_probe(&geodewdt_driver, geodewdt_probe);
268 	if (ret)
269 		goto err;
270 
271 	return 0;
272 err:
273 	platform_device_unregister(geodewdt_platform_device);
274 	return ret;
275 }
276 
277 static void __exit geodewdt_exit(void)
278 {
279 	platform_device_unregister(geodewdt_platform_device);
280 	platform_driver_unregister(&geodewdt_driver);
281 }
282 
283 module_init(geodewdt_init);
284 module_exit(geodewdt_exit);
285 
286 MODULE_AUTHOR("Advanced Micro Devices, Inc");
287 MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver");
288 MODULE_LICENSE("GPL");
289