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
36 static bool nowayout = WATCHDOG_NOWAYOUT;
37 static unsigned int heartbeat = 30; /* (secs) Default is 0.5 minute */
38 static unsigned long wdt_status;
39
40 #define WDT_IN_USE 0
41 #define WDT_OK_TO_CLOSE 1
42
wdt_enable(void)43 static 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
wdt_disable(void)61 static 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
wdt_keepalive(void)71 static 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
m54xx_wdt_open(struct inode * inode,struct file * file)80 static 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
m54xx_wdt_write(struct file * file,const char * data,size_t len,loff_t * ppos)90 static 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
113 static const struct watchdog_info ident = {
114 .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
115 WDIOF_KEEPALIVEPING,
116 .identity = "Coldfire M54xx Watchdog",
117 };
118
m54xx_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)119 static 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
m54xx_wdt_release(struct inode * inode,struct file * file)165 static 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
180 static 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
190 static struct miscdevice m54xx_wdt_miscdev = {
191 .minor = WATCHDOG_MINOR,
192 .name = "watchdog",
193 .fops = &m54xx_wdt_fops,
194 };
195
m54xx_wdt_init(void)196 static 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
m54xx_wdt_exit(void)207 static void __exit m54xx_wdt_exit(void)
208 {
209 misc_deregister(&m54xx_wdt_miscdev);
210 release_mem_region(MCF_GPT_GCIR0, 4);
211 }
212
213 module_init(m54xx_wdt_init);
214 module_exit(m54xx_wdt_exit);
215
216 MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
217 MODULE_DESCRIPTION("Coldfire M54xx Watchdog");
218
219 module_param(heartbeat, int, 0);
220 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 30s)");
221
222 module_param(nowayout, bool, 0);
223 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
224
225 MODULE_LICENSE("GPL");
226