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_address.h> 28 #include <linux/of_platform.h> 29 #include <linux/module.h> 30 #include <linux/watchdog.h> 31 #include <linux/io.h> 32 #include <linux/uaccess.h> 33 #include <sysdev/fsl_soc.h> 34 35 struct mpc8xxx_wdt { 36 __be32 res0; 37 __be32 swcrr; /* System watchdog control register */ 38 #define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */ 39 #define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */ 40 #define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/ 41 #define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */ 42 __be32 swcnr; /* System watchdog count register */ 43 u8 res1[2]; 44 __be16 swsrr; /* System watchdog service register */ 45 u8 res2[0xF0]; 46 }; 47 48 struct mpc8xxx_wdt_type { 49 int prescaler; 50 bool hw_enabled; 51 }; 52 53 static struct mpc8xxx_wdt __iomem *wd_base; 54 static int mpc8xxx_wdt_init_late(void); 55 56 static u16 timeout = 0xffff; 57 module_param(timeout, ushort, 0); 58 MODULE_PARM_DESC(timeout, 59 "Watchdog timeout in ticks. (0<timeout<65536, default=65535)"); 60 61 static bool reset = 1; 62 module_param(reset, bool, 0); 63 MODULE_PARM_DESC(reset, 64 "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset"); 65 66 static bool nowayout = WATCHDOG_NOWAYOUT; 67 module_param(nowayout, bool, 0); 68 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " 69 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 70 71 /* 72 * We always prescale, but if someone really doesn't want to they can set this 73 * to 0 74 */ 75 static int prescale = 1; 76 77 static DEFINE_SPINLOCK(wdt_spinlock); 78 79 static void mpc8xxx_wdt_keepalive(void) 80 { 81 /* Ping the WDT */ 82 spin_lock(&wdt_spinlock); 83 out_be16(&wd_base->swsrr, 0x556c); 84 out_be16(&wd_base->swsrr, 0xaa39); 85 spin_unlock(&wdt_spinlock); 86 } 87 88 static struct watchdog_device mpc8xxx_wdt_dev; 89 static void mpc8xxx_wdt_timer_ping(unsigned long arg); 90 static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 91 (unsigned long)&mpc8xxx_wdt_dev); 92 93 static void mpc8xxx_wdt_timer_ping(unsigned long arg) 94 { 95 struct watchdog_device *w = (struct watchdog_device *)arg; 96 97 mpc8xxx_wdt_keepalive(); 98 /* We're pinging it twice faster than needed, just to be sure. */ 99 mod_timer(&wdt_timer, jiffies + HZ * w->timeout / 2); 100 } 101 102 static int mpc8xxx_wdt_start(struct watchdog_device *w) 103 { 104 u32 tmp = SWCRR_SWEN; 105 106 /* Good, fire up the show */ 107 if (prescale) 108 tmp |= SWCRR_SWPR; 109 if (reset) 110 tmp |= SWCRR_SWRI; 111 112 tmp |= timeout << 16; 113 114 out_be32(&wd_base->swcrr, tmp); 115 116 del_timer_sync(&wdt_timer); 117 118 return 0; 119 } 120 121 static int mpc8xxx_wdt_ping(struct watchdog_device *w) 122 { 123 mpc8xxx_wdt_keepalive(); 124 return 0; 125 } 126 127 static int mpc8xxx_wdt_stop(struct watchdog_device *w) 128 { 129 mod_timer(&wdt_timer, jiffies); 130 return 0; 131 } 132 133 static struct watchdog_info mpc8xxx_wdt_info = { 134 .options = WDIOF_KEEPALIVEPING, 135 .firmware_version = 1, 136 .identity = "MPC8xxx", 137 }; 138 139 static struct watchdog_ops mpc8xxx_wdt_ops = { 140 .owner = THIS_MODULE, 141 .start = mpc8xxx_wdt_start, 142 .ping = mpc8xxx_wdt_ping, 143 .stop = mpc8xxx_wdt_stop, 144 }; 145 146 static struct watchdog_device mpc8xxx_wdt_dev = { 147 .info = &mpc8xxx_wdt_info, 148 .ops = &mpc8xxx_wdt_ops, 149 }; 150 151 static const struct of_device_id mpc8xxx_wdt_match[]; 152 static int mpc8xxx_wdt_probe(struct platform_device *ofdev) 153 { 154 int ret; 155 const struct of_device_id *match; 156 struct device_node *np = ofdev->dev.of_node; 157 const struct mpc8xxx_wdt_type *wdt_type; 158 u32 freq = fsl_get_sys_freq(); 159 bool enabled; 160 unsigned int timeout_sec; 161 162 match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev); 163 if (!match) 164 return -EINVAL; 165 wdt_type = match->data; 166 167 if (!freq || freq == -1) 168 return -EINVAL; 169 170 wd_base = of_iomap(np, 0); 171 if (!wd_base) 172 return -ENOMEM; 173 174 enabled = in_be32(&wd_base->swcrr) & SWCRR_SWEN; 175 if (!enabled && wdt_type->hw_enabled) { 176 pr_info("could not be enabled in software\n"); 177 ret = -ENOSYS; 178 goto err_unmap; 179 } 180 181 /* Calculate the timeout in seconds */ 182 if (prescale) 183 timeout_sec = (timeout * wdt_type->prescaler) / freq; 184 else 185 timeout_sec = timeout / freq; 186 187 mpc8xxx_wdt_dev.timeout = timeout_sec; 188 #ifdef MODULE 189 ret = mpc8xxx_wdt_init_late(); 190 if (ret) 191 goto err_unmap; 192 #endif 193 194 pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d (%d seconds)\n", 195 reset ? "reset" : "interrupt", timeout, timeout_sec); 196 197 /* 198 * If the watchdog was previously enabled or we're running on 199 * MPC8xxx, we should ping the wdt from the kernel until the 200 * userspace handles it. 201 */ 202 if (enabled) 203 mod_timer(&wdt_timer, jiffies); 204 return 0; 205 err_unmap: 206 iounmap(wd_base); 207 wd_base = NULL; 208 return ret; 209 } 210 211 static int mpc8xxx_wdt_remove(struct platform_device *ofdev) 212 { 213 pr_crit("Watchdog removed, expect the %s soon!\n", 214 reset ? "reset" : "machine check exception"); 215 del_timer_sync(&wdt_timer); 216 watchdog_unregister_device(&mpc8xxx_wdt_dev); 217 iounmap(wd_base); 218 219 return 0; 220 } 221 222 static const struct of_device_id mpc8xxx_wdt_match[] = { 223 { 224 .compatible = "mpc83xx_wdt", 225 .data = &(struct mpc8xxx_wdt_type) { 226 .prescaler = 0x10000, 227 }, 228 }, 229 { 230 .compatible = "fsl,mpc8610-wdt", 231 .data = &(struct mpc8xxx_wdt_type) { 232 .prescaler = 0x10000, 233 .hw_enabled = true, 234 }, 235 }, 236 { 237 .compatible = "fsl,mpc823-wdt", 238 .data = &(struct mpc8xxx_wdt_type) { 239 .prescaler = 0x800, 240 .hw_enabled = true, 241 }, 242 }, 243 {}, 244 }; 245 MODULE_DEVICE_TABLE(of, mpc8xxx_wdt_match); 246 247 static struct platform_driver mpc8xxx_wdt_driver = { 248 .probe = mpc8xxx_wdt_probe, 249 .remove = mpc8xxx_wdt_remove, 250 .driver = { 251 .name = "mpc8xxx_wdt", 252 .owner = THIS_MODULE, 253 .of_match_table = mpc8xxx_wdt_match, 254 }, 255 }; 256 257 /* 258 * We do wdt initialization in two steps: arch_initcall probes the wdt 259 * very early to start pinging the watchdog (misc devices are not yet 260 * available), and later module_init() just registers the misc device. 261 */ 262 static int mpc8xxx_wdt_init_late(void) 263 { 264 int ret; 265 266 if (!wd_base) 267 return -ENODEV; 268 269 watchdog_set_nowayout(&mpc8xxx_wdt_dev, nowayout); 270 271 ret = watchdog_register_device(&mpc8xxx_wdt_dev); 272 if (ret) { 273 pr_err("cannot register watchdog device (err=%d)\n", ret); 274 return ret; 275 } 276 return 0; 277 } 278 #ifndef MODULE 279 module_init(mpc8xxx_wdt_init_late); 280 #endif 281 282 static int __init mpc8xxx_wdt_init(void) 283 { 284 return platform_driver_register(&mpc8xxx_wdt_driver); 285 } 286 arch_initcall(mpc8xxx_wdt_init); 287 288 static void __exit mpc8xxx_wdt_exit(void) 289 { 290 platform_driver_unregister(&mpc8xxx_wdt_driver); 291 } 292 module_exit(mpc8xxx_wdt_exit); 293 294 MODULE_AUTHOR("Dave Updegraff, Kumar Gala"); 295 MODULE_DESCRIPTION("Driver for watchdog timer in MPC8xx/MPC83xx/MPC86xx " 296 "uProcessors"); 297 MODULE_LICENSE("GPL"); 298