[go: nahoru, domu]
1/*
2 * drivers/watchdog/m54xx_wdt.c
3 *
4 * Watchdog driver for ColdFire MCF547x & MCF548x processors
5 * Copyright 2010 (c) Philippe De Muyter <phdm@macqel.be>
6 *
7 * Adapted from the IXP4xx watchdog driver, which 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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21#include <linux/module.h>
22#include <linux/moduleparam.h>
23#include <linux/types.h>
24#include <linux/kernel.h>
25#include <linux/fs.h>
26#include <linux/miscdevice.h>
27#include <linux/watchdog.h>
28#include <linux/init.h>
29#include <linux/bitops.h>
30#include <linux/ioport.h>
31#include <linux/uaccess.h>
32
33#include <asm/coldfire.h>
34#include <asm/m54xxsim.h>
35#include <asm/m54xxgpt.h>
36
37static bool nowayout = WATCHDOG_NOWAYOUT;
38static unsigned int heartbeat = 30;	/* (secs) Default is 0.5 minute */
39static unsigned long wdt_status;
40
41#define	WDT_IN_USE		0
42#define	WDT_OK_TO_CLOSE		1
43
44static void wdt_enable(void)
45{
46	unsigned int gms0;
47
48	/* preserve GPIO usage, if any */
49	gms0 = __raw_readl(MCF_GPT_GMS0);
50	if (gms0 & MCF_GPT_GMS_TMS_GPIO)
51		gms0 &= (MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_GPIO_MASK
52							| MCF_GPT_GMS_OD);
53	else
54		gms0 = MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_OD;
55	__raw_writel(gms0, MCF_GPT_GMS0);
56	__raw_writel(MCF_GPT_GCIR_PRE(heartbeat*(MCF_BUSCLK/0xffff)) |
57			MCF_GPT_GCIR_CNT(0xffff), MCF_GPT_GCIR0);
58	gms0 |= MCF_GPT_GMS_OCPW(0xA5) | MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE;
59	__raw_writel(gms0, MCF_GPT_GMS0);
60}
61
62static void wdt_disable(void)
63{
64	unsigned int gms0;
65
66	/* disable watchdog */
67	gms0 = __raw_readl(MCF_GPT_GMS0);
68	gms0 &= ~(MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE);
69	__raw_writel(gms0, MCF_GPT_GMS0);
70}
71
72static void wdt_keepalive(void)
73{
74	unsigned int gms0;
75
76	gms0 = __raw_readl(MCF_GPT_GMS0);
77	gms0 |= MCF_GPT_GMS_OCPW(0xA5);
78	__raw_writel(gms0, MCF_GPT_GMS0);
79}
80
81static int m54xx_wdt_open(struct inode *inode, struct file *file)
82{
83	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
84		return -EBUSY;
85
86	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
87	wdt_enable();
88	return nonseekable_open(inode, file);
89}
90
91static ssize_t m54xx_wdt_write(struct file *file, const char *data,
92						size_t len, loff_t *ppos)
93{
94	if (len) {
95		if (!nowayout) {
96			size_t i;
97
98			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
99
100			for (i = 0; i != len; i++) {
101				char c;
102
103				if (get_user(c, data + i))
104					return -EFAULT;
105				if (c == 'V')
106					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
107			}
108		}
109		wdt_keepalive();
110	}
111	return len;
112}
113
114static const struct watchdog_info ident = {
115	.options	= WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
116				WDIOF_KEEPALIVEPING,
117	.identity	= "Coldfire M54xx Watchdog",
118};
119
120static long m54xx_wdt_ioctl(struct file *file, unsigned int cmd,
121							 unsigned long arg)
122{
123	int ret = -ENOTTY;
124	int time;
125
126	switch (cmd) {
127	case WDIOC_GETSUPPORT:
128		ret = copy_to_user((struct watchdog_info *)arg, &ident,
129				   sizeof(ident)) ? -EFAULT : 0;
130		break;
131
132	case WDIOC_GETSTATUS:
133		ret = put_user(0, (int *)arg);
134		break;
135
136	case WDIOC_GETBOOTSTATUS:
137		ret = put_user(0, (int *)arg);
138		break;
139
140	case WDIOC_KEEPALIVE:
141		wdt_keepalive();
142		ret = 0;
143		break;
144
145	case WDIOC_SETTIMEOUT:
146		ret = get_user(time, (int *)arg);
147		if (ret)
148			break;
149
150		if (time <= 0 || time > 30) {
151			ret = -EINVAL;
152			break;
153		}
154
155		heartbeat = time;
156		wdt_enable();
157		/* Fall through */
158
159	case WDIOC_GETTIMEOUT:
160		ret = put_user(heartbeat, (int *)arg);
161		break;
162	}
163	return ret;
164}
165
166static int m54xx_wdt_release(struct inode *inode, struct file *file)
167{
168	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
169		wdt_disable();
170	else {
171		pr_crit("Device closed unexpectedly - timer will not stop\n");
172		wdt_keepalive();
173	}
174	clear_bit(WDT_IN_USE, &wdt_status);
175	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
176
177	return 0;
178}
179
180
181static const struct file_operations m54xx_wdt_fops = {
182	.owner		= THIS_MODULE,
183	.llseek		= no_llseek,
184	.write		= m54xx_wdt_write,
185	.unlocked_ioctl	= m54xx_wdt_ioctl,
186	.open		= m54xx_wdt_open,
187	.release	= m54xx_wdt_release,
188};
189
190static struct miscdevice m54xx_wdt_miscdev = {
191	.minor		= WATCHDOG_MINOR,
192	.name		= "watchdog",
193	.fops		= &m54xx_wdt_fops,
194};
195
196static int __init m54xx_wdt_init(void)
197{
198	if (!request_mem_region(MCF_GPT_GCIR0, 4, "Coldfire M54xx Watchdog")) {
199		pr_warn("I/O region busy\n");
200		return -EBUSY;
201	}
202	pr_info("driver is loaded\n");
203
204	return misc_register(&m54xx_wdt_miscdev);
205}
206
207static void __exit m54xx_wdt_exit(void)
208{
209	misc_deregister(&m54xx_wdt_miscdev);
210	release_mem_region(MCF_GPT_GCIR0, 4);
211}
212
213module_init(m54xx_wdt_init);
214module_exit(m54xx_wdt_exit);
215
216MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
217MODULE_DESCRIPTION("Coldfire M54xx Watchdog");
218
219module_param(heartbeat, int, 0);
220MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 30s)");
221
222module_param(nowayout, bool, 0);
223MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
224
225MODULE_LICENSE("GPL");
226