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 #include <linux/io.h> 33 34 #include <asm/coldfire.h> 35 #include <asm/m54xxsim.h> 36 #include <asm/m54xxgpt.h> 37 38 static bool nowayout = WATCHDOG_NOWAYOUT; 39 static unsigned int heartbeat = 30; /* (secs) Default is 0.5 minute */ 40 static unsigned long wdt_status; 41 42 #define WDT_IN_USE 0 43 #define WDT_OK_TO_CLOSE 1 44 45 static void wdt_enable(void) 46 { 47 unsigned int gms0; 48 49 /* preserve GPIO usage, if any */ 50 gms0 = __raw_readl(MCF_GPT_GMS0); 51 if (gms0 & MCF_GPT_GMS_TMS_GPIO) 52 gms0 &= (MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_GPIO_MASK 53 | MCF_GPT_GMS_OD); 54 else 55 gms0 = MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_OD; 56 __raw_writel(gms0, MCF_GPT_GMS0); 57 __raw_writel(MCF_GPT_GCIR_PRE(heartbeat*(MCF_BUSCLK/0xffff)) | 58 MCF_GPT_GCIR_CNT(0xffff), MCF_GPT_GCIR0); 59 gms0 |= MCF_GPT_GMS_OCPW(0xA5) | MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE; 60 __raw_writel(gms0, MCF_GPT_GMS0); 61 } 62 63 static void wdt_disable(void) 64 { 65 unsigned int gms0; 66 67 /* disable watchdog */ 68 gms0 = __raw_readl(MCF_GPT_GMS0); 69 gms0 &= ~(MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE); 70 __raw_writel(gms0, MCF_GPT_GMS0); 71 } 72 73 static void wdt_keepalive(void) 74 { 75 unsigned int gms0; 76 77 gms0 = __raw_readl(MCF_GPT_GMS0); 78 gms0 |= MCF_GPT_GMS_OCPW(0xA5); 79 __raw_writel(gms0, MCF_GPT_GMS0); 80 } 81 82 static int m54xx_wdt_open(struct inode *inode, struct file *file) 83 { 84 if (test_and_set_bit(WDT_IN_USE, &wdt_status)) 85 return -EBUSY; 86 87 clear_bit(WDT_OK_TO_CLOSE, &wdt_status); 88 wdt_enable(); 89 return stream_open(inode, file); 90 } 91 92 static ssize_t m54xx_wdt_write(struct file *file, const char *data, 93 size_t len, loff_t *ppos) 94 { 95 if (len) { 96 if (!nowayout) { 97 size_t i; 98 99 clear_bit(WDT_OK_TO_CLOSE, &wdt_status); 100 101 for (i = 0; i != len; i++) { 102 char c; 103 104 if (get_user(c, data + i)) 105 return -EFAULT; 106 if (c == 'V') 107 set_bit(WDT_OK_TO_CLOSE, &wdt_status); 108 } 109 } 110 wdt_keepalive(); 111 } 112 return len; 113 } 114 115 static const struct watchdog_info ident = { 116 .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | 117 WDIOF_KEEPALIVEPING, 118 .identity = "Coldfire M54xx Watchdog", 119 }; 120 121 static long m54xx_wdt_ioctl(struct file *file, unsigned int cmd, 122 unsigned long arg) 123 { 124 int ret = -ENOTTY; 125 int time; 126 127 switch (cmd) { 128 case WDIOC_GETSUPPORT: 129 ret = copy_to_user((struct watchdog_info *)arg, &ident, 130 sizeof(ident)) ? -EFAULT : 0; 131 break; 132 133 case WDIOC_GETSTATUS: 134 ret = put_user(0, (int *)arg); 135 break; 136 137 case WDIOC_GETBOOTSTATUS: 138 ret = put_user(0, (int *)arg); 139 break; 140 141 case WDIOC_KEEPALIVE: 142 wdt_keepalive(); 143 ret = 0; 144 break; 145 146 case WDIOC_SETTIMEOUT: 147 ret = get_user(time, (int *)arg); 148 if (ret) 149 break; 150 151 if (time <= 0 || time > 30) { 152 ret = -EINVAL; 153 break; 154 } 155 156 heartbeat = time; 157 wdt_enable(); 158 /* Fall through */ 159 160 case WDIOC_GETTIMEOUT: 161 ret = put_user(heartbeat, (int *)arg); 162 break; 163 } 164 return ret; 165 } 166 167 static int m54xx_wdt_release(struct inode *inode, struct file *file) 168 { 169 if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) 170 wdt_disable(); 171 else { 172 pr_crit("Device closed unexpectedly - timer will not stop\n"); 173 wdt_keepalive(); 174 } 175 clear_bit(WDT_IN_USE, &wdt_status); 176 clear_bit(WDT_OK_TO_CLOSE, &wdt_status); 177 178 return 0; 179 } 180 181 182 static const struct file_operations m54xx_wdt_fops = { 183 .owner = THIS_MODULE, 184 .llseek = no_llseek, 185 .write = m54xx_wdt_write, 186 .unlocked_ioctl = m54xx_wdt_ioctl, 187 .compat_ioctl = compat_ptr_ioctl, 188 .open = m54xx_wdt_open, 189 .release = m54xx_wdt_release, 190 }; 191 192 static struct miscdevice m54xx_wdt_miscdev = { 193 .minor = WATCHDOG_MINOR, 194 .name = "watchdog", 195 .fops = &m54xx_wdt_fops, 196 }; 197 198 static int __init m54xx_wdt_init(void) 199 { 200 if (!request_mem_region(MCF_GPT_GCIR0, 4, "Coldfire M54xx Watchdog")) { 201 pr_warn("I/O region busy\n"); 202 return -EBUSY; 203 } 204 pr_info("driver is loaded\n"); 205 206 return misc_register(&m54xx_wdt_miscdev); 207 } 208 209 static void __exit m54xx_wdt_exit(void) 210 { 211 misc_deregister(&m54xx_wdt_miscdev); 212 release_mem_region(MCF_GPT_GCIR0, 4); 213 } 214 215 module_init(m54xx_wdt_init); 216 module_exit(m54xx_wdt_exit); 217 218 MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>"); 219 MODULE_DESCRIPTION("Coldfire M54xx Watchdog"); 220 221 module_param(heartbeat, int, 0); 222 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 30s)"); 223 224 module_param(nowayout, bool, 0); 225 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"); 226 227 MODULE_LICENSE("GPL"); 228