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 bool 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 const struct of_device_id mpc8xxx_wdt_match[]; 189 static int __devinit mpc8xxx_wdt_probe(struct platform_device *ofdev) 190 { 191 int ret; 192 const struct of_device_id *match; 193 struct device_node *np = ofdev->dev.of_node; 194 struct mpc8xxx_wdt_type *wdt_type; 195 u32 freq = fsl_get_sys_freq(); 196 bool enabled; 197 198 match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev); 199 if (!match) 200 return -EINVAL; 201 wdt_type = match->data; 202 203 if (!freq || freq == -1) 204 return -EINVAL; 205 206 wd_base = of_iomap(np, 0); 207 if (!wd_base) 208 return -ENOMEM; 209 210 enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN; 211 if (!enabled && wdt_type->hw_enabled) { 212 pr_info("mpc8xxx_wdt: could not be enabled in software\n"); 213 ret = -ENOSYS; 214 goto err_unmap; 215 } 216 217 /* Calculate the timeout in seconds */ 218 if (prescale) 219 timeout_sec = (timeout * wdt_type->prescaler) / freq; 220 else 221 timeout_sec = timeout / freq; 222 223 #ifdef MODULE 224 ret = mpc8xxx_wdt_init_late(); 225 if (ret) 226 goto err_unmap; 227 #endif 228 229 pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d " 230 "(%d seconds)\n", reset ? "reset" : "interrupt", timeout, 231 timeout_sec); 232 233 /* 234 * If the watchdog was previously enabled or we're running on 235 * MPC8xxx, we should ping the wdt from the kernel until the 236 * userspace handles it. 237 */ 238 if (enabled) 239 mpc8xxx_wdt_timer_ping(0); 240 return 0; 241 err_unmap: 242 iounmap(wd_base); 243 wd_base = NULL; 244 return ret; 245 } 246 247 static int __devexit mpc8xxx_wdt_remove(struct platform_device *ofdev) 248 { 249 mpc8xxx_wdt_pr_warn("watchdog removed"); 250 del_timer_sync(&wdt_timer); 251 misc_deregister(&mpc8xxx_wdt_miscdev); 252 iounmap(wd_base); 253 254 return 0; 255 } 256 257 static const struct of_device_id mpc8xxx_wdt_match[] = { 258 { 259 .compatible = "mpc83xx_wdt", 260 .data = &(struct mpc8xxx_wdt_type) { 261 .prescaler = 0x10000, 262 }, 263 }, 264 { 265 .compatible = "fsl,mpc8610-wdt", 266 .data = &(struct mpc8xxx_wdt_type) { 267 .prescaler = 0x10000, 268 .hw_enabled = true, 269 }, 270 }, 271 { 272 .compatible = "fsl,mpc823-wdt", 273 .data = &(struct mpc8xxx_wdt_type) { 274 .prescaler = 0x800, 275 }, 276 }, 277 {}, 278 }; 279 MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match); 280 281 static struct platform_driver mpc8xxx_wdt_driver = { 282 .probe = mpc8xxx_wdt_probe, 283 .remove = __devexit_p(mpc8xxx_wdt_remove), 284 .driver = { 285 .name = "mpc8xxx_wdt", 286 .owner = THIS_MODULE, 287 .of_match_table = mpc8xxx_wdt_match, 288 }, 289 }; 290 291 /* 292 * We do wdt initialization in two steps: arch_initcall probes the wdt 293 * very early to start pinging the watchdog (misc devices are not yet 294 * available), and later module_init() just registers the misc device. 295 */ 296 static int mpc8xxx_wdt_init_late(void) 297 { 298 int ret; 299 300 if (!wd_base) 301 return -ENODEV; 302 303 ret = misc_register(&mpc8xxx_wdt_miscdev); 304 if (ret) { 305 pr_err("cannot register miscdev on minor=%d (err=%d)\n", 306 WATCHDOG_MINOR, ret); 307 return ret; 308 } 309 return 0; 310 } 311 #ifndef MODULE 312 module_init(mpc8xxx_wdt_init_late); 313 #endif 314 315 static int __init mpc8xxx_wdt_init(void) 316 { 317 return platform_driver_register(&mpc8xxx_wdt_driver); 318 } 319 arch_initcall(mpc8xxx_wdt_init); 320 321 static void __exit mpc8xxx_wdt_exit(void) 322 { 323 platform_driver_unregister(&mpc8xxx_wdt_driver); 324 } 325 module_exit(mpc8xxx_wdt_exit); 326 327 MODULE_AUTHOR("Dave Updegraff, Kumar Gala"); 328 MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx " 329 "uProcessors"); 330 MODULE_LICENSE("GPL"); 331 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 332