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#include <asm/mach-au1x00/au1000.h>
45
46#define MTX1_WDT_INTERVAL	(5 * HZ)
47
48static int ticks = 100 * HZ;
49
50static struct {
51	struct completion stop;
52	spinlock_t lock;
53	int running;
54	struct timer_list timer;
55	int queue;
56	int default_ticks;
57	unsigned long inuse;
58	struct gpio_desc *gpiod;
59	unsigned int gstate;
60} mtx1_wdt_device;
61
62static void mtx1_wdt_trigger(struct timer_list *unused)
63{
64	spin_lock(&mtx1_wdt_device.lock);
65	if (mtx1_wdt_device.running)
66		ticks--;
67
68	/* toggle wdt gpio */
69	mtx1_wdt_device.gstate = !mtx1_wdt_device.gstate;
70	gpiod_set_value(mtx1_wdt_device.gpiod, mtx1_wdt_device.gstate);
71
72	if (mtx1_wdt_device.queue && ticks)
73		mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
74	else
75		complete(&mtx1_wdt_device.stop);
76	spin_unlock(&mtx1_wdt_device.lock);
77}
78
79static void mtx1_wdt_reset(void)
80{
81	ticks = mtx1_wdt_device.default_ticks;
82}
83
84
85static void mtx1_wdt_start(void)
86{
87	unsigned long flags;
88
89	spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
90	if (!mtx1_wdt_device.queue) {
91		mtx1_wdt_device.queue = 1;
92		mtx1_wdt_device.gstate = 1;
93		gpiod_set_value(mtx1_wdt_device.gpiod, 1);
94		mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
95	}
96	mtx1_wdt_device.running++;
97	spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
98}
99
100static int mtx1_wdt_stop(void)
101{
102	unsigned long flags;
103
104	spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
105	if (mtx1_wdt_device.queue) {
106		mtx1_wdt_device.queue = 0;
107		mtx1_wdt_device.gstate = 0;
108		gpiod_set_value(mtx1_wdt_device.gpiod, 0);
109	}
110	ticks = mtx1_wdt_device.default_ticks;
111	spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
112	return 0;
113}
114
115/* Filesystem functions */
116
117static int mtx1_wdt_open(struct inode *inode, struct file *file)
118{
119	if (test_and_set_bit(0, &mtx1_wdt_device.inuse))
120		return -EBUSY;
121	return stream_open(inode, file);
122}
123
124
125static int mtx1_wdt_release(struct inode *inode, struct file *file)
126{
127	clear_bit(0, &mtx1_wdt_device.inuse);
128	return 0;
129}
130
131static long mtx1_wdt_ioctl(struct file *file, unsigned int cmd,
132							unsigned long arg)
133{
134	void __user *argp = (void __user *)arg;
135	int __user *p = (int __user *)argp;
136	unsigned int value;
137	static const struct watchdog_info ident = {
138		.options = WDIOF_CARDRESET,
139		.identity = "MTX-1 WDT",
140	};
141
142	switch (cmd) {
143	case WDIOC_GETSUPPORT:
144		if (copy_to_user(argp, &ident, sizeof(ident)))
145			return -EFAULT;
146		break;
147	case WDIOC_GETSTATUS:
148	case WDIOC_GETBOOTSTATUS:
149		put_user(0, p);
150		break;
151	case WDIOC_SETOPTIONS:
152		if (get_user(value, p))
153			return -EFAULT;
154		if (value & WDIOS_ENABLECARD)
155			mtx1_wdt_start();
156		else if (value & WDIOS_DISABLECARD)
157			mtx1_wdt_stop();
158		else
159			return -EINVAL;
160		return 0;
161	case WDIOC_KEEPALIVE:
162		mtx1_wdt_reset();
163		break;
164	default:
165		return -ENOTTY;
166	}
167	return 0;
168}
169
170
171static ssize_t mtx1_wdt_write(struct file *file, const char *buf,
172						size_t count, loff_t *ppos)
173{
174	if (!count)
175		return -EIO;
176	mtx1_wdt_reset();
177	return count;
178}
179
180static const struct file_operations mtx1_wdt_fops = {
181	.owner		= THIS_MODULE,
182	.llseek		= no_llseek,
183	.unlocked_ioctl	= mtx1_wdt_ioctl,
184	.compat_ioctl	= compat_ptr_ioctl,
185	.open		= mtx1_wdt_open,
186	.write		= mtx1_wdt_write,
187	.release	= mtx1_wdt_release,
188};
189
190
191static struct miscdevice mtx1_wdt_misc = {
192	.minor	= WATCHDOG_MINOR,
193	.name	= "watchdog",
194	.fops	= &mtx1_wdt_fops,
195};
196
197
198static int mtx1_wdt_probe(struct platform_device *pdev)
199{
200	int ret;
201
202	mtx1_wdt_device.gpiod = devm_gpiod_get(&pdev->dev,
203					       NULL, GPIOD_OUT_HIGH);
204	if (IS_ERR(mtx1_wdt_device.gpiod)) {
205		dev_err(&pdev->dev, "failed to request gpio");
206		return PTR_ERR(mtx1_wdt_device.gpiod);
207	}
208
209	spin_lock_init(&mtx1_wdt_device.lock);
210	init_completion(&mtx1_wdt_device.stop);
211	mtx1_wdt_device.queue = 0;
212	clear_bit(0, &mtx1_wdt_device.inuse);
213	timer_setup(&mtx1_wdt_device.timer, mtx1_wdt_trigger, 0);
214	mtx1_wdt_device.default_ticks = ticks;
215
216	ret = misc_register(&mtx1_wdt_misc);
217	if (ret < 0) {
218		dev_err(&pdev->dev, "failed to register\n");
219		return ret;
220	}
221	mtx1_wdt_start();
222	dev_info(&pdev->dev, "MTX-1 Watchdog driver\n");
223	return 0;
224}
225
226static int mtx1_wdt_remove(struct platform_device *pdev)
227{
228	/* FIXME: do we need to lock this test ? */
229	if (mtx1_wdt_device.queue) {
230		mtx1_wdt_device.queue = 0;
231		wait_for_completion(&mtx1_wdt_device.stop);
232	}
233
234	misc_deregister(&mtx1_wdt_misc);
235	return 0;
236}
237
238static struct platform_driver mtx1_wdt_driver = {
239	.probe = mtx1_wdt_probe,
240	.remove = mtx1_wdt_remove,
241	.driver.name = "mtx1-wdt",
242	.driver.owner = THIS_MODULE,
243};
244
245module_platform_driver(mtx1_wdt_driver);
246
247MODULE_AUTHOR("Michael Stickel, Florian Fainelli");
248MODULE_DESCRIPTION("Driver for the MTX-1 watchdog");
249MODULE_LICENSE("GPL");
250MODULE_ALIAS("platform:mtx1-wdt");
251