1/*
2 * drivers/char/watchdog/ixp4xx_wdt.c
3 *
4 * Watchdog driver for Intel IXP4xx network processors
5 *
6 * Author: Deepak Saxena <dsaxena@plexity.net>
7 *
8 * Copyright 2004 (c) MontaVista, Software, Inc.
9 * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
10 *
11 * This file is licensed under  the terms of the GNU General Public
12 * License version 2. This program is licensed "as is" without any
13 * warranty of any kind, whether express or implied.
14 */
15
16#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
17
18#include <linux/module.h>
19#include <linux/moduleparam.h>
20#include <linux/types.h>
21#include <linux/kernel.h>
22#include <linux/fs.h>
23#include <linux/miscdevice.h>
24#include <linux/watchdog.h>
25#include <linux/init.h>
26#include <linux/bitops.h>
27#include <linux/uaccess.h>
28#include <mach/hardware.h>
29
30static bool nowayout = WATCHDOG_NOWAYOUT;
31static int heartbeat = 60;	/* (secs) Default is 1 minute */
32static unsigned long wdt_status;
33static unsigned long boot_status;
34static DEFINE_SPINLOCK(wdt_lock);
35
36#define WDT_TICK_RATE (IXP4XX_PERIPHERAL_BUS_CLOCK * 1000000UL)
37
38#define	WDT_IN_USE		0
39#define	WDT_OK_TO_CLOSE		1
40
41static void wdt_enable(void)
42{
43	spin_lock(&wdt_lock);
44	*IXP4XX_OSWK = IXP4XX_WDT_KEY;
45	*IXP4XX_OSWE = 0;
46	*IXP4XX_OSWT = WDT_TICK_RATE * heartbeat;
47	*IXP4XX_OSWE = IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE;
48	*IXP4XX_OSWK = 0;
49	spin_unlock(&wdt_lock);
50}
51
52static void wdt_disable(void)
53{
54	spin_lock(&wdt_lock);
55	*IXP4XX_OSWK = IXP4XX_WDT_KEY;
56	*IXP4XX_OSWE = 0;
57	*IXP4XX_OSWK = 0;
58	spin_unlock(&wdt_lock);
59}
60
61static int ixp4xx_wdt_open(struct inode *inode, struct file *file)
62{
63	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
64		return -EBUSY;
65
66	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
67	wdt_enable();
68	return nonseekable_open(inode, file);
69}
70
71static ssize_t
72ixp4xx_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
73{
74	if (len) {
75		if (!nowayout) {
76			size_t i;
77
78			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
79
80			for (i = 0; i != len; i++) {
81				char c;
82
83				if (get_user(c, data + i))
84					return -EFAULT;
85				if (c == 'V')
86					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
87			}
88		}
89		wdt_enable();
90	}
91	return len;
92}
93
94static const struct watchdog_info ident = {
95	.options	= WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
96			  WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
97	.identity	= "IXP4xx Watchdog",
98};
99
100
101static long ixp4xx_wdt_ioctl(struct file *file, unsigned int cmd,
102							unsigned long arg)
103{
104	int ret = -ENOTTY;
105	int time;
106
107	switch (cmd) {
108	case WDIOC_GETSUPPORT:
109		ret = copy_to_user((struct watchdog_info *)arg, &ident,
110				   sizeof(ident)) ? -EFAULT : 0;
111		break;
112
113	case WDIOC_GETSTATUS:
114		ret = put_user(0, (int *)arg);
115		break;
116
117	case WDIOC_GETBOOTSTATUS:
118		ret = put_user(boot_status, (int *)arg);
119		break;
120
121	case WDIOC_KEEPALIVE:
122		wdt_enable();
123		ret = 0;
124		break;
125
126	case WDIOC_SETTIMEOUT:
127		ret = get_user(time, (int *)arg);
128		if (ret)
129			break;
130
131		if (time <= 0 || time > 60) {
132			ret = -EINVAL;
133			break;
134		}
135
136		heartbeat = time;
137		wdt_enable();
138		/* Fall through */
139
140	case WDIOC_GETTIMEOUT:
141		ret = put_user(heartbeat, (int *)arg);
142		break;
143	}
144	return ret;
145}
146
147static int ixp4xx_wdt_release(struct inode *inode, struct file *file)
148{
149	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
150		wdt_disable();
151	else
152		pr_crit("Device closed unexpectedly - timer will not stop\n");
153	clear_bit(WDT_IN_USE, &wdt_status);
154	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
155
156	return 0;
157}
158
159
160static const struct file_operations ixp4xx_wdt_fops = {
161	.owner		= THIS_MODULE,
162	.llseek		= no_llseek,
163	.write		= ixp4xx_wdt_write,
164	.unlocked_ioctl	= ixp4xx_wdt_ioctl,
165	.open		= ixp4xx_wdt_open,
166	.release	= ixp4xx_wdt_release,
167};
168
169static struct miscdevice ixp4xx_wdt_miscdev = {
170	.minor		= WATCHDOG_MINOR,
171	.name		= "watchdog",
172	.fops		= &ixp4xx_wdt_fops,
173};
174
175static int __init ixp4xx_wdt_init(void)
176{
177	int ret;
178
179	if (!(read_cpuid_id() & 0xf) && !cpu_is_ixp46x()) {
180		pr_err("Rev. A0 IXP42x CPU detected - watchdog disabled\n");
181
182		return -ENODEV;
183	}
184	boot_status = (*IXP4XX_OSST & IXP4XX_OSST_TIMER_WARM_RESET) ?
185			WDIOF_CARDRESET : 0;
186	ret = misc_register(&ixp4xx_wdt_miscdev);
187	if (ret == 0)
188		pr_info("timer heartbeat %d sec\n", heartbeat);
189	return ret;
190}
191
192static void __exit ixp4xx_wdt_exit(void)
193{
194	misc_deregister(&ixp4xx_wdt_miscdev);
195}
196
197
198module_init(ixp4xx_wdt_init);
199module_exit(ixp4xx_wdt_exit);
200
201MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
202MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog");
203
204module_param(heartbeat, int, 0);
205MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
206
207module_param(nowayout, bool, 0);
208MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
209
210MODULE_LICENSE("GPL");
211