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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 21 22 #include <linux/fs.h> 23 #include <linux/init.h> 24 #include <linux/kernel.h> 25 #include <linux/timer.h> 26 #include <linux/miscdevice.h> 27 #include <linux/of_platform.h> 28 #include <linux/module.h> 29 #include <linux/watchdog.h> 30 #include <linux/io.h> 31 #include <linux/uaccess.h> 32 #include <sysdev/fsl_soc.h> 33 34 struct mpc8xxx_wdt { 35 __be32 res0; 36 __be32 swcrr; /* System watchdog control register */ 37 #define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */ 38 #define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */ 39 #define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/ 40 #define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */ 41 __be32 swcnr; /* System watchdog count register */ 42 u8 res1[2]; 43 __be16 swsrr; /* System watchdog service register */ 44 u8 res2[0xF0]; 45 }; 46 47 struct mpc8xxx_wdt_type { 48 int prescaler; 49 bool hw_enabled; 50 }; 51 52 static struct mpc8xxx_wdt __iomem *wd_base; 53 static int mpc8xxx_wdt_init_late(void); 54 55 static u16 timeout = 0xffff; 56 module_param(timeout, ushort, 0); 57 MODULE_PARM_DESC(timeout, 58 "Watchdog timeout in ticks. (0<timeout<65536, default=65535)"); 59 60 static bool reset = 1; 61 module_param(reset, bool, 0); 62 MODULE_PARM_DESC(reset, 63 "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset"); 64 65 static bool nowayout = WATCHDOG_NOWAYOUT; 66 module_param(nowayout, bool, 0); 67 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " 68 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 69 70 /* 71 * We always prescale, but if someone really doesn't want to they can set this 72 * to 0 73 */ 74 static int prescale = 1; 75 static unsigned int timeout_sec; 76 77 static unsigned long wdt_is_open; 78 static DEFINE_SPINLOCK(wdt_spinlock); 79 80 static void mpc8xxx_wdt_keepalive(void) 81 { 82 /* Ping the WDT */ 83 spin_lock(&wdt_spinlock); 84 out_be16(&wd_base->swsrr, 0x556c); 85 out_be16(&wd_base->swsrr, 0xaa39); 86 spin_unlock(&wdt_spinlock); 87 } 88 89 static void mpc8xxx_wdt_timer_ping(unsigned long arg); 90 static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0); 91 92 static void mpc8xxx_wdt_timer_ping(unsigned long arg) 93 { 94 mpc8xxx_wdt_keepalive(); 95 /* We're pinging it twice faster than needed, just to be sure. */ 96 mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2); 97 } 98 99 static void mpc8xxx_wdt_pr_warn(const char *msg) 100 { 101 pr_crit("%s, expect the %s soon!\n", msg, 102 reset ? "reset" : "machine check exception"); 103 } 104 105 static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf, 106 size_t count, loff_t *ppos) 107 { 108 if (count) 109 mpc8xxx_wdt_keepalive(); 110 return count; 111 } 112 113 static int mpc8xxx_wdt_open(struct inode *inode, struct file *file) 114 { 115 u32 tmp = SWCRR_SWEN; 116 if (test_and_set_bit(0, &wdt_is_open)) 117 return -EBUSY; 118 119 /* Once we start the watchdog we can't stop it */ 120 if (nowayout) 121 __module_get(THIS_MODULE); 122 123 /* Good, fire up the show */ 124 if (prescale) 125 tmp |= SWCRR_SWPR; 126 if (reset) 127 tmp |= SWCRR_SWRI; 128 129 tmp |= timeout << 16; 130 131 out_be32(&wd_base->swcrr, tmp); 132 133 del_timer_sync(&wdt_timer); 134 135 return nonseekable_open(inode, file); 136 } 137 138 static int mpc8xxx_wdt_release(struct inode *inode, struct file *file) 139 { 140 if (!nowayout) 141 mpc8xxx_wdt_timer_ping(0); 142 else 143 mpc8xxx_wdt_pr_warn("watchdog closed"); 144 clear_bit(0, &wdt_is_open); 145 return 0; 146 } 147 148 static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd, 149 unsigned long arg) 150 { 151 void __user *argp = (void __user *)arg; 152 int __user *p = argp; 153 static const struct watchdog_info ident = { 154 .options = WDIOF_KEEPALIVEPING, 155 .firmware_version = 1, 156 .identity = "MPC8xxx", 157 }; 158 159 switch (cmd) { 160 case WDIOC_GETSUPPORT: 161 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; 162 case WDIOC_GETSTATUS: 163 case WDIOC_GETBOOTSTATUS: 164 return put_user(0, p); 165 case WDIOC_KEEPALIVE: 166 mpc8xxx_wdt_keepalive(); 167 return 0; 168 case WDIOC_GETTIMEOUT: 169 return put_user(timeout_sec, p); 170 default: 171 return -ENOTTY; 172 } 173 } 174 175 static const struct file_operations mpc8xxx_wdt_fops = { 176 .owner = THIS_MODULE, 177 .llseek = no_llseek, 178 .write = mpc8xxx_wdt_write, 179 .unlocked_ioctl = mpc8xxx_wdt_ioctl, 180 .open = mpc8xxx_wdt_open, 181 .release = mpc8xxx_wdt_release, 182 }; 183 184 static struct miscdevice mpc8xxx_wdt_miscdev = { 185 .minor = WATCHDOG_MINOR, 186 .name = "watchdog", 187 .fops = &mpc8xxx_wdt_fops, 188 }; 189 190 static const struct of_device_id mpc8xxx_wdt_match[]; 191 static int mpc8xxx_wdt_probe(struct platform_device *ofdev) 192 { 193 int ret; 194 const struct of_device_id *match; 195 struct device_node *np = ofdev->dev.of_node; 196 const struct mpc8xxx_wdt_type *wdt_type; 197 u32 freq = fsl_get_sys_freq(); 198 bool enabled; 199 200 match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev); 201 if (!match) 202 return -EINVAL; 203 wdt_type = match->data; 204 205 if (!freq || freq == -1) 206 return -EINVAL; 207 208 wd_base = of_iomap(np, 0); 209 if (!wd_base) 210 return -ENOMEM; 211 212 enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN; 213 if (!enabled && wdt_type->hw_enabled) { 214 pr_info("could not be enabled in software\n"); 215 ret = -ENOSYS; 216 goto err_unmap; 217 } 218 219 /* Calculate the timeout in seconds */ 220 if (prescale) 221 timeout_sec = (timeout * wdt_type->prescaler) / freq; 222 else 223 timeout_sec = timeout / freq; 224 225 #ifdef MODULE 226 ret = mpc8xxx_wdt_init_late(); 227 if (ret) 228 goto err_unmap; 229 #endif 230 231 pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d (%d seconds)\n", 232 reset ? "reset" : "interrupt", timeout, timeout_sec); 233 234 /* 235 * If the watchdog was previously enabled or we're running on 236 * MPC8xxx, we should ping the wdt from the kernel until the 237 * userspace handles it. 238 */ 239 if (enabled) 240 mpc8xxx_wdt_timer_ping(0); 241 return 0; 242 err_unmap: 243 iounmap(wd_base); 244 wd_base = NULL; 245 return ret; 246 } 247 248 static int mpc8xxx_wdt_remove(struct platform_device *ofdev) 249 { 250 mpc8xxx_wdt_pr_warn("watchdog removed"); 251 del_timer_sync(&wdt_timer); 252 misc_deregister(&mpc8xxx_wdt_miscdev); 253 iounmap(wd_base); 254 255 return 0; 256 } 257 258 static const struct of_device_id mpc8xxx_wdt_match[] = { 259 { 260 .compatible = "mpc83xx_wdt", 261 .data = &(struct mpc8xxx_wdt_type) { 262 .prescaler = 0x10000, 263 }, 264 }, 265 { 266 .compatible = "fsl,mpc8610-wdt", 267 .data = &(struct mpc8xxx_wdt_type) { 268 .prescaler = 0x10000, 269 .hw_enabled = true, 270 }, 271 }, 272 { 273 .compatible = "fsl,mpc823-wdt", 274 .data = &(struct mpc8xxx_wdt_type) { 275 .prescaler = 0x800, 276 }, 277 }, 278 {}, 279 }; 280 MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match); 281 282 static struct platform_driver mpc8xxx_wdt_driver = { 283 .probe = mpc8xxx_wdt_probe, 284 .remove = mpc8xxx_wdt_remove, 285 .driver = { 286 .name = "mpc8xxx_wdt", 287 .owner = THIS_MODULE, 288 .of_match_table = mpc8xxx_wdt_match, 289 }, 290 }; 291 292 /* 293 * We do wdt initialization in two steps: arch_initcall probes the wdt 294 * very early to start pinging the watchdog (misc devices are not yet 295 * available), and later module_init() just registers the misc device. 296 */ 297 static int mpc8xxx_wdt_init_late(void) 298 { 299 int ret; 300 301 if (!wd_base) 302 return -ENODEV; 303 304 ret = misc_register(&mpc8xxx_wdt_miscdev); 305 if (ret) { 306 pr_err("cannot register miscdev on minor=%d (err=%d)\n", 307 WATCHDOG_MINOR, ret); 308 return ret; 309 } 310 return 0; 311 } 312 #ifndef MODULE 313 module_init(mpc8xxx_wdt_init_late); 314 #endif 315 316 static int __init mpc8xxx_wdt_init(void) 317 { 318 return platform_driver_register(&mpc8xxx_wdt_driver); 319 } 320 arch_initcall(mpc8xxx_wdt_init); 321 322 static void __exit mpc8xxx_wdt_exit(void) 323 { 324 platform_driver_unregister(&mpc8xxx_wdt_driver); 325 } 326 module_exit(mpc8xxx_wdt_exit); 327 328 MODULE_AUTHOR("Dave Updegraff, Kumar Gala"); 329 MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx " 330 "uProcessors"); 331 MODULE_LICENSE("GPL"); 332 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 333