1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Watchdog driver for SBC-FITPC2 board 4 * 5 * Author: Denis Turischev <denis@compulab.co.il> 6 * 7 * Adapted from the IXP2000 watchdog driver by Deepak Saxena. 8 * 9 */ 10 11 #define pr_fmt(fmt) KBUILD_MODNAME " WATCHDOG: " fmt 12 13 #include <linux/module.h> 14 #include <linux/types.h> 15 #include <linux/miscdevice.h> 16 #include <linux/watchdog.h> 17 #include <linux/ioport.h> 18 #include <linux/delay.h> 19 #include <linux/fs.h> 20 #include <linux/init.h> 21 #include <linux/moduleparam.h> 22 #include <linux/dmi.h> 23 #include <linux/io.h> 24 #include <linux/uaccess.h> 25 26 27 static bool nowayout = WATCHDOG_NOWAYOUT; 28 static unsigned int margin = 60; /* (secs) Default is 1 minute */ 29 static unsigned long wdt_status; 30 static DEFINE_MUTEX(wdt_lock); 31 32 #define WDT_IN_USE 0 33 #define WDT_OK_TO_CLOSE 1 34 35 #define COMMAND_PORT 0x4c 36 #define DATA_PORT 0x48 37 38 #define IFACE_ON_COMMAND 1 39 #define REBOOT_COMMAND 2 40 41 #define WATCHDOG_NAME "SBC-FITPC2 Watchdog" 42 43 static void wdt_send_data(unsigned char command, unsigned char data) 44 { 45 outb(data, DATA_PORT); 46 msleep(200); 47 outb(command, COMMAND_PORT); 48 msleep(100); 49 } 50 51 static void wdt_enable(void) 52 { 53 mutex_lock(&wdt_lock); 54 wdt_send_data(IFACE_ON_COMMAND, 1); 55 wdt_send_data(REBOOT_COMMAND, margin); 56 mutex_unlock(&wdt_lock); 57 } 58 59 static void wdt_disable(void) 60 { 61 mutex_lock(&wdt_lock); 62 wdt_send_data(IFACE_ON_COMMAND, 0); 63 wdt_send_data(REBOOT_COMMAND, 0); 64 mutex_unlock(&wdt_lock); 65 } 66 67 static int fitpc2_wdt_open(struct inode *inode, struct file *file) 68 { 69 if (test_and_set_bit(WDT_IN_USE, &wdt_status)) 70 return -EBUSY; 71 72 clear_bit(WDT_OK_TO_CLOSE, &wdt_status); 73 74 wdt_enable(); 75 76 return stream_open(inode, file); 77 } 78 79 static ssize_t fitpc2_wdt_write(struct file *file, const char __user *data, 80 size_t len, loff_t *ppos) 81 { 82 size_t i; 83 84 if (!len) 85 return 0; 86 87 if (nowayout) { 88 len = 0; 89 goto out; 90 } 91 92 clear_bit(WDT_OK_TO_CLOSE, &wdt_status); 93 94 for (i = 0; i != len; i++) { 95 char c; 96 97 if (get_user(c, data + i)) 98 return -EFAULT; 99 100 if (c == 'V') 101 set_bit(WDT_OK_TO_CLOSE, &wdt_status); 102 } 103 104 out: 105 wdt_enable(); 106 107 return len; 108 } 109 110 111 static const struct watchdog_info ident = { 112 .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | 113 WDIOF_KEEPALIVEPING, 114 .identity = WATCHDOG_NAME, 115 }; 116 117 118 static long fitpc2_wdt_ioctl(struct file *file, unsigned int cmd, 119 unsigned long arg) 120 { 121 int ret = -ENOTTY; 122 int time; 123 124 switch (cmd) { 125 case WDIOC_GETSUPPORT: 126 ret = copy_to_user((struct watchdog_info __user *)arg, &ident, 127 sizeof(ident)) ? -EFAULT : 0; 128 break; 129 130 case WDIOC_GETSTATUS: 131 ret = put_user(0, (int __user *)arg); 132 break; 133 134 case WDIOC_GETBOOTSTATUS: 135 ret = put_user(0, (int __user *)arg); 136 break; 137 138 case WDIOC_KEEPALIVE: 139 wdt_enable(); 140 ret = 0; 141 break; 142 143 case WDIOC_SETTIMEOUT: 144 ret = get_user(time, (int __user *)arg); 145 if (ret) 146 break; 147 148 if (time < 31 || time > 255) { 149 ret = -EINVAL; 150 break; 151 } 152 153 margin = time; 154 wdt_enable(); 155 fallthrough; 156 157 case WDIOC_GETTIMEOUT: 158 ret = put_user(margin, (int __user *)arg); 159 break; 160 } 161 162 return ret; 163 } 164 165 static int fitpc2_wdt_release(struct inode *inode, struct file *file) 166 { 167 if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) { 168 wdt_disable(); 169 pr_info("Device disabled\n"); 170 } else { 171 pr_warn("Device closed unexpectedly - timer will not stop\n"); 172 wdt_enable(); 173 } 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 fitpc2_wdt_fops = { 183 .owner = THIS_MODULE, 184 .write = fitpc2_wdt_write, 185 .unlocked_ioctl = fitpc2_wdt_ioctl, 186 .compat_ioctl = compat_ptr_ioctl, 187 .open = fitpc2_wdt_open, 188 .release = fitpc2_wdt_release, 189 }; 190 191 static struct miscdevice fitpc2_wdt_miscdev = { 192 .minor = WATCHDOG_MINOR, 193 .name = "watchdog", 194 .fops = &fitpc2_wdt_fops, 195 }; 196 197 static int __init fitpc2_wdt_init(void) 198 { 199 int err; 200 const char *brd_name; 201 202 brd_name = dmi_get_system_info(DMI_BOARD_NAME); 203 204 if (!brd_name || !strstr(brd_name, "SBC-FITPC2")) 205 return -ENODEV; 206 207 pr_info("%s found\n", brd_name); 208 209 if (!request_region(COMMAND_PORT, 1, WATCHDOG_NAME)) { 210 pr_err("I/O address 0x%04x already in use\n", COMMAND_PORT); 211 return -EIO; 212 } 213 214 if (!request_region(DATA_PORT, 1, WATCHDOG_NAME)) { 215 pr_err("I/O address 0x%04x already in use\n", DATA_PORT); 216 err = -EIO; 217 goto err_data_port; 218 } 219 220 if (margin < 31 || margin > 255) { 221 pr_err("margin must be in range 31 - 255 seconds, you tried to set %d\n", 222 margin); 223 err = -EINVAL; 224 goto err_margin; 225 } 226 227 err = misc_register(&fitpc2_wdt_miscdev); 228 if (err) { 229 pr_err("cannot register miscdev on minor=%d (err=%d)\n", 230 WATCHDOG_MINOR, err); 231 goto err_margin; 232 } 233 234 return 0; 235 236 err_margin: 237 release_region(DATA_PORT, 1); 238 err_data_port: 239 release_region(COMMAND_PORT, 1); 240 241 return err; 242 } 243 244 static void __exit fitpc2_wdt_exit(void) 245 { 246 misc_deregister(&fitpc2_wdt_miscdev); 247 release_region(DATA_PORT, 1); 248 release_region(COMMAND_PORT, 1); 249 } 250 251 module_init(fitpc2_wdt_init); 252 module_exit(fitpc2_wdt_exit); 253 254 MODULE_AUTHOR("Denis Turischev <denis@compulab.co.il>"); 255 MODULE_DESCRIPTION("SBC-FITPC2 Watchdog"); 256 257 module_param(margin, int, 0); 258 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)"); 259 260 module_param(nowayout, bool, 0); 261 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"); 262 263 MODULE_LICENSE("GPL"); 264