1/*
2 * drivers/char/watchdog/ixp2000_wdt.c
3 *
4 * Watchdog driver for Intel IXP2000 network processors
5 *
6 * Adapted from the IXP4xx watchdog driver by Lennert Buytenhek.
7 * The original version carries these notices:
8 *
9 * Author: Deepak Saxena <dsaxena@plexity.net>
10 *
11 * Copyright 2004 (c) MontaVista, Software, Inc.
12 * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
13 *
14 * This file is licensed under  the terms of the GNU General Public
15 * License version 2. This program is licensed "as is" without any
16 * warranty of any kind, whether express or implied.
17 */
18
19#include <linux/module.h>
20#include <linux/moduleparam.h>
21#include <linux/types.h>
22#include <linux/kernel.h>
23#include <linux/fs.h>
24#include <linux/miscdevice.h>
25#include <linux/watchdog.h>
26#include <linux/init.h>
27#include <linux/bitops.h>
28
29#include <asm/hardware.h>
30#include <asm/uaccess.h>
31
32static int nowayout = WATCHDOG_NOWAYOUT;
33static unsigned int heartbeat = 60;	/* (secs) Default is 1 minute */
34static unsigned long wdt_status;
35
36#define	WDT_IN_USE		0
37#define	WDT_OK_TO_CLOSE		1
38
39static unsigned long wdt_tick_rate;
40
41static void
42wdt_enable(void)
43{
44	ixp2000_reg_write(IXP2000_RESET0, *(IXP2000_RESET0) | WDT_RESET_ENABLE);
45	ixp2000_reg_write(IXP2000_TWDE, WDT_ENABLE);
46	ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
47	ixp2000_reg_write(IXP2000_T4_CTL, TIMER_DIVIDER_256 | TIMER_ENABLE);
48}
49
50static void
51wdt_disable(void)
52{
53	ixp2000_reg_write(IXP2000_T4_CTL, 0);
54}
55
56static void
57wdt_keepalive(void)
58{
59	ixp2000_reg_write(IXP2000_T4_CLD, heartbeat * wdt_tick_rate);
60}
61
62static int
63ixp2000_wdt_open(struct inode *inode, struct file *file)
64{
65	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
66		return -EBUSY;
67
68	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
69
70	wdt_enable();
71
72	return nonseekable_open(inode, file);
73}
74
75static ssize_t
76ixp2000_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
77{
78	if (len) {
79		if (!nowayout) {
80			size_t i;
81
82			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
83
84			for (i = 0; i != len; i++) {
85				char c;
86
87				if (get_user(c, data + i))
88					return -EFAULT;
89				if (c == 'V')
90					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
91			}
92		}
93		wdt_keepalive();
94	}
95
96	return len;
97}
98
99
100static struct watchdog_info ident = {
101	.options	= WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
102				WDIOF_KEEPALIVEPING,
103	.identity	= "IXP2000 Watchdog",
104};
105
106static int
107ixp2000_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
108			unsigned long arg)
109{
110	int ret = -ENOTTY;
111	int time;
112
113	switch (cmd) {
114	case WDIOC_GETSUPPORT:
115		ret = copy_to_user((struct watchdog_info *)arg, &ident,
116				   sizeof(ident)) ? -EFAULT : 0;
117		break;
118
119	case WDIOC_GETSTATUS:
120		ret = put_user(0, (int *)arg);
121		break;
122
123	case WDIOC_GETBOOTSTATUS:
124		ret = put_user(0, (int *)arg);
125		break;
126
127	case WDIOC_SETTIMEOUT:
128		ret = get_user(time, (int *)arg);
129		if (ret)
130			break;
131
132		if (time <= 0 || time > 60) {
133			ret = -EINVAL;
134			break;
135		}
136
137		heartbeat = time;
138		wdt_keepalive();
139		/* Fall through */
140
141	case WDIOC_GETTIMEOUT:
142		ret = put_user(heartbeat, (int *)arg);
143		break;
144
145	case WDIOC_KEEPALIVE:
146		wdt_enable();
147		ret = 0;
148		break;
149	}
150
151	return ret;
152}
153
154static int
155ixp2000_wdt_release(struct inode *inode, struct file *file)
156{
157	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) {
158		wdt_disable();
159	} else {
160		printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
161					"timer will not stop\n");
162	}
163
164	clear_bit(WDT_IN_USE, &wdt_status);
165	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
166
167	return 0;
168}
169
170
171static const struct file_operations ixp2000_wdt_fops =
172{
173	.owner		= THIS_MODULE,
174	.llseek		= no_llseek,
175	.write		= ixp2000_wdt_write,
176	.ioctl		= ixp2000_wdt_ioctl,
177	.open		= ixp2000_wdt_open,
178	.release	= ixp2000_wdt_release,
179};
180
181static struct miscdevice ixp2000_wdt_miscdev =
182{
183	.minor		= WATCHDOG_MINOR,
184	.name		= "watchdog",
185	.fops		= &ixp2000_wdt_fops,
186};
187
188static int __init ixp2000_wdt_init(void)
189{
190	if ((*IXP2000_PRODUCT_ID & 0x001ffef0) == 0x00000000) {
191		printk(KERN_INFO "Unable to use IXP2000 watchdog due to IXP2800 erratum #25.\n");
192		return -EIO;
193	}
194
195	wdt_tick_rate = (*IXP2000_T1_CLD * HZ) / 256;
196
197	return misc_register(&ixp2000_wdt_miscdev);
198}
199
200static void __exit ixp2000_wdt_exit(void)
201{
202	misc_deregister(&ixp2000_wdt_miscdev);
203}
204
205module_init(ixp2000_wdt_init);
206module_exit(ixp2000_wdt_exit);
207
208MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
209MODULE_DESCRIPTION("IXP2000 Network Processor Watchdog");
210
211module_param(heartbeat, int, 0);
212MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
213
214module_param(nowayout, int, 0);
215MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
216
217MODULE_LICENSE("GPL");
218MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
219