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 37 static bool nowayout = WATCHDOG_NOWAYOUT; 38 static unsigned int heartbeat = 30; /* (secs) Default is 0.5 minute */ 39 static unsigned long wdt_status; 40 41 #define WDT_IN_USE 0 42 #define WDT_OK_TO_CLOSE 1 43 44 static 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 62 static 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 72 static 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 81 static 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 stream_open(inode, file); 89 } 90 91 static 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 } 113 114 static const struct watchdog_info ident = { 115 .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | 116 WDIOF_KEEPALIVEPING, 117 .identity = "Coldfire M54xx Watchdog", 118 }; 119 120 static 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 } 165 166 static 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 } 179 180 181 static 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 .compat_ioctl = compat_ptr_ioctl, 187 .open = m54xx_wdt_open, 188 .release = m54xx_wdt_release, 189 }; 190 191 static struct miscdevice m54xx_wdt_miscdev = { 192 .minor = WATCHDOG_MINOR, 193 .name = "watchdog", 194 .fops = &m54xx_wdt_fops, 195 }; 196 197 static int __init m54xx_wdt_init(void) 198 { 199 if (!request_mem_region(MCF_GPT_GCIR0, 4, "Coldfire M54xx Watchdog")) { 200 pr_warn("I/O region busy\n"); 201 return -EBUSY; 202 } 203 pr_info("driver is loaded\n"); 204 205 return misc_register(&m54xx_wdt_miscdev); 206 } 207 208 static void __exit m54xx_wdt_exit(void) 209 { 210 misc_deregister(&m54xx_wdt_miscdev); 211 release_mem_region(MCF_GPT_GCIR0, 4); 212 } 213 214 module_init(m54xx_wdt_init); 215 module_exit(m54xx_wdt_exit); 216 217 MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>"); 218 MODULE_DESCRIPTION("Coldfire M54xx Watchdog"); 219 220 module_param(heartbeat, int, 0); 221 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 30s)"); 222 223 module_param(nowayout, bool, 0); 224 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"); 225 226 MODULE_LICENSE("GPL"); 227