1 /* 2 * mpc8xxx_wdt.c - MPC8xx/MPC83xx/MPC86xx watchdog userspace interface 3 * 4 * Authors: Dave Updegraff <dave@cray.org> 5 * Kumar Gala <galak@kernel.crashing.org> 6 * Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org> 7 * ..and from sc520_wdt 8 * Copyright (c) 2008 MontaVista Software, Inc. 9 * Anton Vorontsov <avorontsov@ru.mvista.com> 10 * 11 * Note: it appears that you can only actually ENABLE or DISABLE the thing 12 * once after POR. Once enabled, you cannot disable, and vice versa. 13 * 14 * This program is free software; you can redistribute it and/or modify it 15 * under the terms of the GNU General Public License as published by the 16 * Free Software Foundation; either version 2 of the License, or (at your 17 * option) any later version. 18 */ 19 20 #include <linux/fs.h> 21 #include <linux/init.h> 22 #include <linux/kernel.h> 23 #include <linux/timer.h> 24 #include <linux/miscdevice.h> 25 #include <linux/of_platform.h> 26 #include <linux/module.h> 27 #include <linux/watchdog.h> 28 #include <linux/io.h> 29 #include <linux/uaccess.h> 30 #include <sysdev/fsl_soc.h> 31 32 struct mpc8xxx_wdt { 33 __be32 res0; 34 __be32 swcrr; /* System watchdog control register */ 35 #define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */ 36 #define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */ 37 #define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/ 38 #define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */ 39 __be32 swcnr; /* System watchdog count register */ 40 u8 res1[2]; 41 __be16 swsrr; /* System watchdog service register */ 42 u8 res2[0xF0]; 43 }; 44 45 struct mpc8xxx_wdt_type { 46 int prescaler; 47 bool hw_enabled; 48 }; 49 50 static struct mpc8xxx_wdt __iomem *wd_base; 51 static int mpc8xxx_wdt_init_late(void); 52 53 static u16 timeout = 0xffff; 54 module_param(timeout, ushort, 0); 55 MODULE_PARM_DESC(timeout, 56 "Watchdog timeout in ticks. (0<timeout<65536, default=65535)"); 57 58 static int reset = 1; 59 module_param(reset, bool, 0); 60 MODULE_PARM_DESC(reset, 61 "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset"); 62 63 static int nowayout = WATCHDOG_NOWAYOUT; 64 module_param(nowayout, int, 0); 65 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " 66 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 67 68 /* 69 * We always prescale, but if someone really doesn't want to they can set this 70 * to 0 71 */ 72 static int prescale = 1; 73 static unsigned int timeout_sec; 74 75 static unsigned long wdt_is_open; 76 static DEFINE_SPINLOCK(wdt_spinlock); 77 78 static void mpc8xxx_wdt_keepalive(void) 79 { 80 /* Ping the WDT */ 81 spin_lock(&wdt_spinlock); 82 out_be16(&wd_base->swsrr, 0x556c); 83 out_be16(&wd_base->swsrr, 0xaa39); 84 spin_unlock(&wdt_spinlock); 85 } 86 87 static void mpc8xxx_wdt_timer_ping(unsigned long arg); 88 static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0); 89 90 static void mpc8xxx_wdt_timer_ping(unsigned long arg) 91 { 92 mpc8xxx_wdt_keepalive(); 93 /* We're pinging it twice faster than needed, just to be sure. */ 94 mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2); 95 } 96 97 static void mpc8xxx_wdt_pr_warn(const char *msg) 98 { 99 pr_crit("mpc8xxx_wdt: %s, expect the %s soon!\n", msg, 100 reset ? "reset" : "machine check exception"); 101 } 102 103 static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf, 104 size_t count, loff_t *ppos) 105 { 106 if (count) 107 mpc8xxx_wdt_keepalive(); 108 return count; 109 } 110 111 static int mpc8xxx_wdt_open(struct inode *inode, struct file *file) 112 { 113 u32 tmp = SWCRR_SWEN; 114 if (test_and_set_bit(0, &wdt_is_open)) 115 return -EBUSY; 116 117 /* Once we start the watchdog we can't stop it */ 118 if (nowayout) 119 __module_get(THIS_MODULE); 120 121 /* Good, fire up the show */ 122 if (prescale) 123 tmp |= SWCRR_SWPR; 124 if (reset) 125 tmp |= SWCRR_SWRI; 126 127 tmp |= timeout << 16; 128 129 out_be32(&wd_base->swcrr, tmp); 130 131 del_timer_sync(&wdt_timer); 132 133 return nonseekable_open(inode, file); 134 } 135 136 static int mpc8xxx_wdt_release(struct inode *inode, struct file *file) 137 { 138 if (!nowayout) 139 mpc8xxx_wdt_timer_ping(0); 140 else 141 mpc8xxx_wdt_pr_warn("watchdog closed"); 142 clear_bit(0, &wdt_is_open); 143 return 0; 144 } 145 146 static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd, 147 unsigned long arg) 148 { 149 void __user *argp = (void __user *)arg; 150 int __user *p = argp; 151 static const struct watchdog_info ident = { 152 .options = WDIOF_KEEPALIVEPING, 153 .firmware_version = 1, 154 .identity = "MPC8xxx", 155 }; 156 157 switch (cmd) { 158 case WDIOC_GETSUPPORT: 159 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; 160 case WDIOC_GETSTATUS: 161 case WDIOC_GETBOOTSTATUS: 162 return put_user(0, p); 163 case WDIOC_KEEPALIVE: 164 mpc8xxx_wdt_keepalive(); 165 return 0; 166 case WDIOC_GETTIMEOUT: 167 return put_user(timeout_sec, p); 168 default: 169 return -ENOTTY; 170 } 171 } 172 173 static const struct file_operations mpc8xxx_wdt_fops = { 174 .owner = THIS_MODULE, 175 .llseek = no_llseek, 176 .write = mpc8xxx_wdt_write, 177 .unlocked_ioctl = mpc8xxx_wdt_ioctl, 178 .open = mpc8xxx_wdt_open, 179 .release = mpc8xxx_wdt_release, 180 }; 181 182 static struct miscdevice mpc8xxx_wdt_miscdev = { 183 .minor = WATCHDOG_MINOR, 184 .name = "watchdog", 185 .fops = &mpc8xxx_wdt_fops, 186 }; 187 188 static int __devinit mpc8xxx_wdt_probe(struct of_device *ofdev, 189 const struct of_device_id *match) 190 { 191 int ret; 192 struct device_node *np = ofdev->dev.of_node; 193 struct mpc8xxx_wdt_type *wdt_type = match->data; 194 u32 freq = fsl_get_sys_freq(); 195 bool enabled; 196 197 if (!freq || freq == -1) 198 return -EINVAL; 199 200 wd_base = of_iomap(np, 0); 201 if (!wd_base) 202 return -ENOMEM; 203 204 enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN; 205 if (!enabled && wdt_type->hw_enabled) { 206 pr_info("mpc8xxx_wdt: could not be enabled in software\n"); 207 ret = -ENOSYS; 208 goto err_unmap; 209 } 210 211 /* Calculate the timeout in seconds */ 212 if (prescale) 213 timeout_sec = (timeout * wdt_type->prescaler) / freq; 214 else 215 timeout_sec = timeout / freq; 216 217 #ifdef MODULE 218 ret = mpc8xxx_wdt_init_late(); 219 if (ret) 220 goto err_unmap; 221 #endif 222 223 pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d " 224 "(%d seconds)\n", reset ? "reset" : "interrupt", timeout, 225 timeout_sec); 226 227 /* 228 * If the watchdog was previously enabled or we're running on 229 * MPC8xxx, we should ping the wdt from the kernel until the 230 * userspace handles it. 231 */ 232 if (enabled) 233 mpc8xxx_wdt_timer_ping(0); 234 return 0; 235 err_unmap: 236 iounmap(wd_base); 237 wd_base = NULL; 238 return ret; 239 } 240 241 static int __devexit mpc8xxx_wdt_remove(struct of_device *ofdev) 242 { 243 mpc8xxx_wdt_pr_warn("watchdog removed"); 244 del_timer_sync(&wdt_timer); 245 misc_deregister(&mpc8xxx_wdt_miscdev); 246 iounmap(wd_base); 247 248 return 0; 249 } 250 251 static const struct of_device_id mpc8xxx_wdt_match[] = { 252 { 253 .compatible = "mpc83xx_wdt", 254 .data = &(struct mpc8xxx_wdt_type) { 255 .prescaler = 0x10000, 256 }, 257 }, 258 { 259 .compatible = "fsl,mpc8610-wdt", 260 .data = &(struct mpc8xxx_wdt_type) { 261 .prescaler = 0x10000, 262 .hw_enabled = true, 263 }, 264 }, 265 { 266 .compatible = "fsl,mpc823-wdt", 267 .data = &(struct mpc8xxx_wdt_type) { 268 .prescaler = 0x800, 269 }, 270 }, 271 {}, 272 }; 273 MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match); 274 275 static struct of_platform_driver mpc8xxx_wdt_driver = { 276 .probe = mpc8xxx_wdt_probe, 277 .remove = __devexit_p(mpc8xxx_wdt_remove), 278 .driver = { 279 .name = "mpc8xxx_wdt", 280 .owner = THIS_MODULE, 281 .of_match_table = mpc8xxx_wdt_match, 282 }, 283 }; 284 285 /* 286 * We do wdt initialization in two steps: arch_initcall probes the wdt 287 * very early to start pinging the watchdog (misc devices are not yet 288 * available), and later module_init() just registers the misc device. 289 */ 290 static int mpc8xxx_wdt_init_late(void) 291 { 292 int ret; 293 294 if (!wd_base) 295 return -ENODEV; 296 297 ret = misc_register(&mpc8xxx_wdt_miscdev); 298 if (ret) { 299 pr_err("cannot register miscdev on minor=%d (err=%d)\n", 300 WATCHDOG_MINOR, ret); 301 return ret; 302 } 303 return 0; 304 } 305 #ifndef MODULE 306 module_init(mpc8xxx_wdt_init_late); 307 #endif 308 309 static int __init mpc8xxx_wdt_init(void) 310 { 311 return of_register_platform_driver(&mpc8xxx_wdt_driver); 312 } 313 arch_initcall(mpc8xxx_wdt_init); 314 315 static void __exit mpc8xxx_wdt_exit(void) 316 { 317 of_unregister_platform_driver(&mpc8xxx_wdt_driver); 318 } 319 module_exit(mpc8xxx_wdt_exit); 320 321 MODULE_AUTHOR("Dave Updegraff, Kumar Gala"); 322 MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx " 323 "uProcessors"); 324 MODULE_LICENSE("GPL"); 325 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 326