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
33static int timeout = WATCHDOG_TIMEOUT;
34module_param(timeout, int, 0);
35MODULE_PARM_DESC(timeout,
36	"Watchdog timeout in seconds. 1<= timeout <=131, default="
37				__MODULE_STRING(WATCHDOG_TIMEOUT) ".");
38
39static bool nowayout = WATCHDOG_NOWAYOUT;
40module_param(nowayout, bool, 0);
41MODULE_PARM_DESC(nowayout,
42	"Watchdog cannot be stopped once started (default="
43				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
44
45static struct platform_device *geodewdt_platform_device;
46static unsigned long wdt_flags;
47static struct cs5535_mfgpt_timer *wdt_timer;
48static int safe_close;
49
50static 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
62static 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
68static 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
82static 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
94static 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
111static 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
135static 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
197static 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
207static struct miscdevice geodewdt_miscdev = {
208	.minor = WATCHDOG_MINOR,
209	.name = "watchdog",
210	.fops = &geodewdt_fops,
211};
212
213static 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(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(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1);
230
231	/* Set up the initial timeout */
232
233	cs5535_mfgpt_write(wdt_timer, MFGPT_REG_CMP2,
234		timeout * GEODEWDT_HZ);
235
236	ret = misc_register(&geodewdt_miscdev);
237
238	return ret;
239}
240
241static void geodewdt_remove(struct platform_device *dev)
242{
243	misc_deregister(&geodewdt_miscdev);
244}
245
246static void geodewdt_shutdown(struct platform_device *dev)
247{
248	geodewdt_disable();
249}
250
251static struct platform_driver geodewdt_driver = {
252	.remove_new	= geodewdt_remove,
253	.shutdown	= geodewdt_shutdown,
254	.driver		= {
255		.name	= DRV_NAME,
256	},
257};
258
259static int __init geodewdt_init(void)
260{
261	int ret;
262
263	geodewdt_platform_device = platform_device_register_simple(DRV_NAME,
264								-1, NULL, 0);
265	if (IS_ERR(geodewdt_platform_device))
266		return PTR_ERR(geodewdt_platform_device);
267
268	ret = platform_driver_probe(&geodewdt_driver, geodewdt_probe);
269	if (ret)
270		goto err;
271
272	return 0;
273err:
274	platform_device_unregister(geodewdt_platform_device);
275	return ret;
276}
277
278static void __exit geodewdt_exit(void)
279{
280	platform_device_unregister(geodewdt_platform_device);
281	platform_driver_unregister(&geodewdt_driver);
282}
283
284module_init(geodewdt_init);
285module_exit(geodewdt_exit);
286
287MODULE_AUTHOR("Advanced Micro Devices, Inc");
288MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver");
289MODULE_LICENSE("GPL");
290