1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* |
3 | * Driver for the MTX-1 Watchdog. |
4 | * |
5 | * (C) Copyright 2005 4G Systems <info@4g-systems.biz>, |
6 | * All Rights Reserved. |
7 | * http://www.4g-systems.biz |
8 | * |
9 | * (C) Copyright 2007 OpenWrt.org, Florian Fainelli <florian@openwrt.org> |
10 | * (c) Copyright 2005 4G Systems <info@4g-systems.biz> |
11 | * |
12 | * Release 0.01. |
13 | * Author: Michael Stickel michael.stickel@4g-systems.biz |
14 | * |
15 | * Release 0.02. |
16 | * Author: Florian Fainelli florian@openwrt.org |
17 | * use the Linux watchdog/timer APIs |
18 | * |
19 | * The Watchdog is configured to reset the MTX-1 |
20 | * if it is not triggered for 100 seconds. |
21 | * It should not be triggered more often than 1.6 seconds. |
22 | * |
23 | * A timer triggers the watchdog every 5 seconds, until |
24 | * it is opened for the first time. After the first open |
25 | * it MUST be triggered every 2..95 seconds. |
26 | */ |
27 | |
28 | #include <linux/module.h> |
29 | #include <linux/moduleparam.h> |
30 | #include <linux/types.h> |
31 | #include <linux/errno.h> |
32 | #include <linux/miscdevice.h> |
33 | #include <linux/fs.h> |
34 | #include <linux/ioport.h> |
35 | #include <linux/timer.h> |
36 | #include <linux/completion.h> |
37 | #include <linux/jiffies.h> |
38 | #include <linux/watchdog.h> |
39 | #include <linux/platform_device.h> |
40 | #include <linux/io.h> |
41 | #include <linux/uaccess.h> |
42 | #include <linux/gpio/consumer.h> |
43 | |
44 | #define MTX1_WDT_INTERVAL (5 * HZ) |
45 | |
46 | static int ticks = 100 * HZ; |
47 | |
48 | static struct { |
49 | struct completion stop; |
50 | spinlock_t lock; |
51 | int running; |
52 | struct timer_list timer; |
53 | int queue; |
54 | int default_ticks; |
55 | unsigned long inuse; |
56 | struct gpio_desc *gpiod; |
57 | unsigned int gstate; |
58 | } mtx1_wdt_device; |
59 | |
60 | static void mtx1_wdt_trigger(struct timer_list *unused) |
61 | { |
62 | spin_lock(lock: &mtx1_wdt_device.lock); |
63 | if (mtx1_wdt_device.running) |
64 | ticks--; |
65 | |
66 | /* toggle wdt gpio */ |
67 | mtx1_wdt_device.gstate = !mtx1_wdt_device.gstate; |
68 | gpiod_set_value(desc: mtx1_wdt_device.gpiod, value: mtx1_wdt_device.gstate); |
69 | |
70 | if (mtx1_wdt_device.queue && ticks) |
71 | mod_timer(timer: &mtx1_wdt_device.timer, expires: jiffies + MTX1_WDT_INTERVAL); |
72 | else |
73 | complete(&mtx1_wdt_device.stop); |
74 | spin_unlock(lock: &mtx1_wdt_device.lock); |
75 | } |
76 | |
77 | static void mtx1_wdt_reset(void) |
78 | { |
79 | ticks = mtx1_wdt_device.default_ticks; |
80 | } |
81 | |
82 | |
83 | static void mtx1_wdt_start(void) |
84 | { |
85 | unsigned long flags; |
86 | |
87 | spin_lock_irqsave(&mtx1_wdt_device.lock, flags); |
88 | if (!mtx1_wdt_device.queue) { |
89 | mtx1_wdt_device.queue = 1; |
90 | mtx1_wdt_device.gstate = 1; |
91 | gpiod_set_value(desc: mtx1_wdt_device.gpiod, value: 1); |
92 | mod_timer(timer: &mtx1_wdt_device.timer, expires: jiffies + MTX1_WDT_INTERVAL); |
93 | } |
94 | mtx1_wdt_device.running++; |
95 | spin_unlock_irqrestore(lock: &mtx1_wdt_device.lock, flags); |
96 | } |
97 | |
98 | static int mtx1_wdt_stop(void) |
99 | { |
100 | unsigned long flags; |
101 | |
102 | spin_lock_irqsave(&mtx1_wdt_device.lock, flags); |
103 | if (mtx1_wdt_device.queue) { |
104 | mtx1_wdt_device.queue = 0; |
105 | mtx1_wdt_device.gstate = 0; |
106 | gpiod_set_value(desc: mtx1_wdt_device.gpiod, value: 0); |
107 | } |
108 | ticks = mtx1_wdt_device.default_ticks; |
109 | spin_unlock_irqrestore(lock: &mtx1_wdt_device.lock, flags); |
110 | return 0; |
111 | } |
112 | |
113 | /* Filesystem functions */ |
114 | |
115 | static int mtx1_wdt_open(struct inode *inode, struct file *file) |
116 | { |
117 | if (test_and_set_bit(nr: 0, addr: &mtx1_wdt_device.inuse)) |
118 | return -EBUSY; |
119 | return stream_open(inode, filp: file); |
120 | } |
121 | |
122 | |
123 | static int mtx1_wdt_release(struct inode *inode, struct file *file) |
124 | { |
125 | clear_bit(nr: 0, addr: &mtx1_wdt_device.inuse); |
126 | return 0; |
127 | } |
128 | |
129 | static long mtx1_wdt_ioctl(struct file *file, unsigned int cmd, |
130 | unsigned long arg) |
131 | { |
132 | void __user *argp = (void __user *)arg; |
133 | int __user *p = (int __user *)argp; |
134 | unsigned int value; |
135 | static const struct watchdog_info ident = { |
136 | .options = WDIOF_CARDRESET, |
137 | .identity = "MTX-1 WDT" , |
138 | }; |
139 | |
140 | switch (cmd) { |
141 | case WDIOC_GETSUPPORT: |
142 | if (copy_to_user(to: argp, from: &ident, n: sizeof(ident))) |
143 | return -EFAULT; |
144 | break; |
145 | case WDIOC_GETSTATUS: |
146 | case WDIOC_GETBOOTSTATUS: |
147 | put_user(0, p); |
148 | break; |
149 | case WDIOC_SETOPTIONS: |
150 | if (get_user(value, p)) |
151 | return -EFAULT; |
152 | if (value & WDIOS_ENABLECARD) |
153 | mtx1_wdt_start(); |
154 | else if (value & WDIOS_DISABLECARD) |
155 | mtx1_wdt_stop(); |
156 | else |
157 | return -EINVAL; |
158 | return 0; |
159 | case WDIOC_KEEPALIVE: |
160 | mtx1_wdt_reset(); |
161 | break; |
162 | default: |
163 | return -ENOTTY; |
164 | } |
165 | return 0; |
166 | } |
167 | |
168 | |
169 | static ssize_t mtx1_wdt_write(struct file *file, const char *buf, |
170 | size_t count, loff_t *ppos) |
171 | { |
172 | if (!count) |
173 | return -EIO; |
174 | mtx1_wdt_reset(); |
175 | return count; |
176 | } |
177 | |
178 | static const struct file_operations mtx1_wdt_fops = { |
179 | .owner = THIS_MODULE, |
180 | .llseek = no_llseek, |
181 | .unlocked_ioctl = mtx1_wdt_ioctl, |
182 | .compat_ioctl = compat_ptr_ioctl, |
183 | .open = mtx1_wdt_open, |
184 | .write = mtx1_wdt_write, |
185 | .release = mtx1_wdt_release, |
186 | }; |
187 | |
188 | |
189 | static struct miscdevice mtx1_wdt_misc = { |
190 | .minor = WATCHDOG_MINOR, |
191 | .name = "watchdog" , |
192 | .fops = &mtx1_wdt_fops, |
193 | }; |
194 | |
195 | |
196 | static int mtx1_wdt_probe(struct platform_device *pdev) |
197 | { |
198 | int ret; |
199 | |
200 | mtx1_wdt_device.gpiod = devm_gpiod_get(dev: &pdev->dev, |
201 | NULL, flags: GPIOD_OUT_HIGH); |
202 | if (IS_ERR(ptr: mtx1_wdt_device.gpiod)) { |
203 | dev_err(&pdev->dev, "failed to request gpio" ); |
204 | return PTR_ERR(ptr: mtx1_wdt_device.gpiod); |
205 | } |
206 | |
207 | spin_lock_init(&mtx1_wdt_device.lock); |
208 | init_completion(x: &mtx1_wdt_device.stop); |
209 | mtx1_wdt_device.queue = 0; |
210 | clear_bit(nr: 0, addr: &mtx1_wdt_device.inuse); |
211 | timer_setup(&mtx1_wdt_device.timer, mtx1_wdt_trigger, 0); |
212 | mtx1_wdt_device.default_ticks = ticks; |
213 | |
214 | ret = misc_register(misc: &mtx1_wdt_misc); |
215 | if (ret < 0) { |
216 | dev_err(&pdev->dev, "failed to register\n" ); |
217 | return ret; |
218 | } |
219 | mtx1_wdt_start(); |
220 | dev_info(&pdev->dev, "MTX-1 Watchdog driver\n" ); |
221 | return 0; |
222 | } |
223 | |
224 | static void mtx1_wdt_remove(struct platform_device *pdev) |
225 | { |
226 | /* FIXME: do we need to lock this test ? */ |
227 | if (mtx1_wdt_device.queue) { |
228 | mtx1_wdt_device.queue = 0; |
229 | wait_for_completion(&mtx1_wdt_device.stop); |
230 | } |
231 | |
232 | misc_deregister(misc: &mtx1_wdt_misc); |
233 | } |
234 | |
235 | static struct platform_driver mtx1_wdt_driver = { |
236 | .probe = mtx1_wdt_probe, |
237 | .remove_new = mtx1_wdt_remove, |
238 | .driver.name = "mtx1-wdt" , |
239 | .driver.owner = THIS_MODULE, |
240 | }; |
241 | |
242 | module_platform_driver(mtx1_wdt_driver); |
243 | |
244 | MODULE_AUTHOR("Michael Stickel, Florian Fainelli" ); |
245 | MODULE_DESCRIPTION("Driver for the MTX-1 watchdog" ); |
246 | MODULE_LICENSE("GPL" ); |
247 | MODULE_ALIAS("platform:mtx1-wdt" ); |
248 | |