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(timer: wdt_timer, MFGPT_REG_SETUP, value: 0); |
54 | |
55 | /* Reset the counter */ |
56 | cs5535_mfgpt_write(timer: wdt_timer, MFGPT_REG_COUNTER, value: 0); |
57 | |
58 | /* Enable the counter */ |
59 | cs5535_mfgpt_write(timer: wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN); |
60 | } |
61 | |
62 | static void geodewdt_disable(void) |
63 | { |
64 | cs5535_mfgpt_write(timer: wdt_timer, MFGPT_REG_SETUP, value: 0); |
65 | cs5535_mfgpt_write(timer: wdt_timer, MFGPT_REG_COUNTER, value: 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(timer: wdt_timer, MFGPT_REG_SETUP, value: 0); |
74 | cs5535_mfgpt_write(timer: wdt_timer, MFGPT_REG_CMP2, value: val * GEODEWDT_HZ); |
75 | cs5535_mfgpt_write(timer: wdt_timer, MFGPT_REG_COUNTER, value: 0); |
76 | cs5535_mfgpt_write(timer: 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, addr: &wdt_flags)) |
85 | return -EBUSY; |
86 | |
87 | if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, addr: &wdt_flags)) |
88 | __module_get(THIS_MODULE); |
89 | |
90 | geodewdt_ping(); |
91 | return stream_open(inode, filp: 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, addr: &wdt_flags); |
104 | } |
105 | |
106 | clear_bit(WDT_FLAGS_OPEN, addr: &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(to: argp, from: &ident, |
152 | n: 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(val: 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 | .llseek = no_llseek, |
200 | .write = geodewdt_write, |
201 | .unlocked_ioctl = geodewdt_ioctl, |
202 | .compat_ioctl = compat_ptr_ioctl, |
203 | .open = geodewdt_open, |
204 | .release = geodewdt_release, |
205 | }; |
206 | |
207 | static struct miscdevice geodewdt_miscdev = { |
208 | .minor = WATCHDOG_MINOR, |
209 | .name = "watchdog" , |
210 | .fops = &geodewdt_fops, |
211 | }; |
212 | |
213 | static int __init geodewdt_probe(struct platform_device *dev) |
214 | { |
215 | int ret; |
216 | |
217 | wdt_timer = cs5535_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING); |
218 | if (!wdt_timer) { |
219 | pr_err("No timers were available\n" ); |
220 | return -ENODEV; |
221 | } |
222 | |
223 | /* Set up the timer */ |
224 | |
225 | cs5535_mfgpt_write(timer: wdt_timer, MFGPT_REG_SETUP, |
226 | GEODEWDT_SCALE | (3 << 8)); |
227 | |
228 | /* Set up comparator 2 to reset when the event fires */ |
229 | cs5535_mfgpt_toggle_event(timer: wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, enable: 1); |
230 | |
231 | /* Set up the initial timeout */ |
232 | |
233 | cs5535_mfgpt_write(timer: wdt_timer, MFGPT_REG_CMP2, |
234 | value: timeout * GEODEWDT_HZ); |
235 | |
236 | ret = misc_register(misc: &geodewdt_miscdev); |
237 | |
238 | return ret; |
239 | } |
240 | |
241 | static void geodewdt_remove(struct platform_device *dev) |
242 | { |
243 | misc_deregister(misc: &geodewdt_miscdev); |
244 | } |
245 | |
246 | static void geodewdt_shutdown(struct platform_device *dev) |
247 | { |
248 | geodewdt_disable(); |
249 | } |
250 | |
251 | static struct platform_driver geodewdt_driver = { |
252 | .remove_new = geodewdt_remove, |
253 | .shutdown = geodewdt_shutdown, |
254 | .driver = { |
255 | .name = DRV_NAME, |
256 | }, |
257 | }; |
258 | |
259 | static int __init geodewdt_init(void) |
260 | { |
261 | int ret; |
262 | |
263 | geodewdt_platform_device = platform_device_register_simple(DRV_NAME, |
264 | id: -1, NULL, num: 0); |
265 | if (IS_ERR(ptr: geodewdt_platform_device)) |
266 | return PTR_ERR(ptr: geodewdt_platform_device); |
267 | |
268 | ret = platform_driver_probe(&geodewdt_driver, geodewdt_probe); |
269 | if (ret) |
270 | goto err; |
271 | |
272 | return 0; |
273 | err: |
274 | platform_device_unregister(geodewdt_platform_device); |
275 | return ret; |
276 | } |
277 | |
278 | static void __exit geodewdt_exit(void) |
279 | { |
280 | platform_device_unregister(geodewdt_platform_device); |
281 | platform_driver_unregister(&geodewdt_driver); |
282 | } |
283 | |
284 | module_init(geodewdt_init); |
285 | module_exit(geodewdt_exit); |
286 | |
287 | MODULE_AUTHOR("Advanced Micro Devices, Inc" ); |
288 | MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver" ); |
289 | MODULE_LICENSE("GPL" ); |
290 | |