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
geodewdt_ping(void)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
geodewdt_disable(void)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
geodewdt_set_heartbeat(int val)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
geodewdt_open(struct inode * inode,struct file * file)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
geodewdt_release(struct inode * inode,struct file * file)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
geodewdt_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)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
geodewdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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 break;
154
155 case WDIOC_GETSTATUS:
156 case WDIOC_GETBOOTSTATUS:
157 return put_user(0, p);
158
159 case WDIOC_SETOPTIONS:
160 {
161 int options, ret = -EINVAL;
162
163 if (get_user(options, p))
164 return -EFAULT;
165
166 if (options & WDIOS_DISABLECARD) {
167 geodewdt_disable();
168 ret = 0;
169 }
170
171 if (options & WDIOS_ENABLECARD) {
172 geodewdt_ping();
173 ret = 0;
174 }
175
176 return ret;
177 }
178 case WDIOC_KEEPALIVE:
179 geodewdt_ping();
180 return 0;
181
182 case WDIOC_SETTIMEOUT:
183 if (get_user(interval, p))
184 return -EFAULT;
185
186 if (geodewdt_set_heartbeat(interval))
187 return -EINVAL;
188 /* Fall through */
189 case WDIOC_GETTIMEOUT:
190 return put_user(timeout, p);
191
192 default:
193 return -ENOTTY;
194 }
195
196 return 0;
197 }
198
199 static const struct file_operations geodewdt_fops = {
200 .owner = THIS_MODULE,
201 .llseek = no_llseek,
202 .write = geodewdt_write,
203 .unlocked_ioctl = geodewdt_ioctl,
204 .open = geodewdt_open,
205 .release = geodewdt_release,
206 };
207
208 static struct miscdevice geodewdt_miscdev = {
209 .minor = WATCHDOG_MINOR,
210 .name = "watchdog",
211 .fops = &geodewdt_fops,
212 };
213
geodewdt_probe(struct platform_device * dev)214 static int __init geodewdt_probe(struct platform_device *dev)
215 {
216 int ret;
217
218 wdt_timer = cs5535_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);
219 if (!wdt_timer) {
220 pr_err("No timers were available\n");
221 return -ENODEV;
222 }
223
224 /* Set up the timer */
225
226 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_SETUP,
227 GEODEWDT_SCALE | (3 << 8));
228
229 /* Set up comparator 2 to reset when the event fires */
230 cs5535_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1);
231
232 /* Set up the initial timeout */
233
234 cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2,
235 timeout * GEODEWDT_HZ);
236
237 ret = misc_register(&geodewdt_miscdev);
238
239 return ret;
240 }
241
geodewdt_remove(struct platform_device * dev)242 static int geodewdt_remove(struct platform_device *dev)
243 {
244 misc_deregister(&geodewdt_miscdev);
245 return 0;
246 }
247
geodewdt_shutdown(struct platform_device * dev)248 static void geodewdt_shutdown(struct platform_device *dev)
249 {
250 geodewdt_disable();
251 }
252
253 static struct platform_driver geodewdt_driver = {
254 .remove = geodewdt_remove,
255 .shutdown = geodewdt_shutdown,
256 .driver = {
257 .name = DRV_NAME,
258 },
259 };
260
geodewdt_init(void)261 static int __init geodewdt_init(void)
262 {
263 int ret;
264
265 geodewdt_platform_device = platform_device_register_simple(DRV_NAME,
266 -1, NULL, 0);
267 if (IS_ERR(geodewdt_platform_device))
268 return PTR_ERR(geodewdt_platform_device);
269
270 ret = platform_driver_probe(&geodewdt_driver, geodewdt_probe);
271 if (ret)
272 goto err;
273
274 return 0;
275 err:
276 platform_device_unregister(geodewdt_platform_device);
277 return ret;
278 }
279
geodewdt_exit(void)280 static void __exit geodewdt_exit(void)
281 {
282 platform_device_unregister(geodewdt_platform_device);
283 platform_driver_unregister(&geodewdt_driver);
284 }
285
286 module_init(geodewdt_init);
287 module_exit(geodewdt_exit);
288
289 MODULE_AUTHOR("Advanced Micro Devices, Inc");
290 MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver");
291 MODULE_LICENSE("GPL");
292
