1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * drivers/watchdog/m54xx_wdt.c
4 *
5 * Watchdog driver for ColdFire MCF547x & MCF548x processors
6 * Copyright 2010 (c) Philippe De Muyter <phdm@macqel.be>
7 *
8 * Adapted from the IXP4xx watchdog driver, which carries these notices:
9 *
10 *  Author: Deepak Saxena <dsaxena@plexity.net>
11 *
12 *  Copyright 2004 (c) MontaVista, Software, Inc.
13 *  Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
14 *
15 */
16
17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/ioport.h>
29#include <linux/uaccess.h>
30#include <linux/io.h>
31
32#include <asm/coldfire.h>
33#include <asm/m54xxsim.h>
34#include <asm/m54xxgpt.h>
35
36static bool nowayout = WATCHDOG_NOWAYOUT;
37static unsigned int heartbeat = 30;	/* (secs) Default is 0.5 minute */
38static unsigned long wdt_status;
39
40#define	WDT_IN_USE		0
41#define	WDT_OK_TO_CLOSE		1
42
43static void wdt_enable(void)
44{
45	unsigned int gms0;
46
47	/* preserve GPIO usage, if any */
48	gms0 = __raw_readl(MCF_GPT_GMS0);
49	if (gms0 & MCF_GPT_GMS_TMS_GPIO)
50		gms0 &= (MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_GPIO_MASK
51							| MCF_GPT_GMS_OD);
52	else
53		gms0 = MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_OD;
54	__raw_writel(gms0, MCF_GPT_GMS0);
55	__raw_writel(MCF_GPT_GCIR_PRE(heartbeat*(MCF_BUSCLK/0xffff)) |
56			MCF_GPT_GCIR_CNT(0xffff), MCF_GPT_GCIR0);
57	gms0 |= MCF_GPT_GMS_OCPW(0xA5) | MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE;
58	__raw_writel(gms0, MCF_GPT_GMS0);
59}
60
61static void wdt_disable(void)
62{
63	unsigned int gms0;
64
65	/* disable watchdog */
66	gms0 = __raw_readl(MCF_GPT_GMS0);
67	gms0 &= ~(MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE);
68	__raw_writel(gms0, MCF_GPT_GMS0);
69}
70
71static void wdt_keepalive(void)
72{
73	unsigned int gms0;
74
75	gms0 = __raw_readl(MCF_GPT_GMS0);
76	gms0 |= MCF_GPT_GMS_OCPW(0xA5);
77	__raw_writel(gms0, MCF_GPT_GMS0);
78}
79
80static int m54xx_wdt_open(struct inode *inode, struct file *file)
81{
82	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
83		return -EBUSY;
84
85	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
86	wdt_enable();
87	return stream_open(inode, file);
88}
89
90static ssize_t m54xx_wdt_write(struct file *file, const char *data,
91						size_t len, loff_t *ppos)
92{
93	if (len) {
94		if (!nowayout) {
95			size_t i;
96
97			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
98
99			for (i = 0; i != len; i++) {
100				char c;
101
102				if (get_user(c, data + i))
103					return -EFAULT;
104				if (c == 'V')
105					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
106			}
107		}
108		wdt_keepalive();
109	}
110	return len;
111}
112
113static const struct watchdog_info ident = {
114	.options	= WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
115				WDIOF_KEEPALIVEPING,
116	.identity	= "Coldfire M54xx Watchdog",
117};
118
119static long m54xx_wdt_ioctl(struct file *file, unsigned int cmd,
120							 unsigned long arg)
121{
122	int ret = -ENOTTY;
123	int time;
124
125	switch (cmd) {
126	case WDIOC_GETSUPPORT:
127		ret = copy_to_user((struct watchdog_info *)arg, &ident,
128				   sizeof(ident)) ? -EFAULT : 0;
129		break;
130
131	case WDIOC_GETSTATUS:
132		ret = put_user(0, (int *)arg);
133		break;
134
135	case WDIOC_GETBOOTSTATUS:
136		ret = put_user(0, (int *)arg);
137		break;
138
139	case WDIOC_KEEPALIVE:
140		wdt_keepalive();
141		ret = 0;
142		break;
143
144	case WDIOC_SETTIMEOUT:
145		ret = get_user(time, (int *)arg);
146		if (ret)
147			break;
148
149		if (time <= 0 || time > 30) {
150			ret = -EINVAL;
151			break;
152		}
153
154		heartbeat = time;
155		wdt_enable();
156		fallthrough;
157
158	case WDIOC_GETTIMEOUT:
159		ret = put_user(heartbeat, (int *)arg);
160		break;
161	}
162	return ret;
163}
164
165static int m54xx_wdt_release(struct inode *inode, struct file *file)
166{
167	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
168		wdt_disable();
169	else {
170		pr_crit("Device closed unexpectedly - timer will not stop\n");
171		wdt_keepalive();
172	}
173	clear_bit(WDT_IN_USE, &wdt_status);
174	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
175
176	return 0;
177}
178
179
180static const struct file_operations m54xx_wdt_fops = {
181	.owner		= THIS_MODULE,
182	.llseek		= no_llseek,
183	.write		= m54xx_wdt_write,
184	.unlocked_ioctl	= m54xx_wdt_ioctl,
185	.compat_ioctl	= compat_ptr_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