1 /* 2 * drivers/watchdog/shwdt.c 3 * 4 * Watchdog driver for integrated watchdog in the SuperH processors. 5 * 6 * Copyright (C) 2001 - 2012 Paul Mundt <lethal@linux-sh.org> 7 * 8 * This program is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License as published by the 10 * Free Software Foundation; either version 2 of the License, or (at your 11 * option) any later version. 12 * 13 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com> 14 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT 15 * 16 * 19-Apr-2002 Rob Radez <rob@osinvestor.com> 17 * Added expect close support, made emulated timeout runtime changeable 18 * general cleanups, add some ioctls 19 */ 20 21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 22 23 #include <linux/module.h> 24 #include <linux/moduleparam.h> 25 #include <linux/platform_device.h> 26 #include <linux/init.h> 27 #include <linux/types.h> 28 #include <linux/spinlock.h> 29 #include <linux/watchdog.h> 30 #include <linux/pm_runtime.h> 31 #include <linux/fs.h> 32 #include <linux/mm.h> 33 #include <linux/slab.h> 34 #include <linux/io.h> 35 #include <linux/clk.h> 36 #include <linux/err.h> 37 #include <asm/watchdog.h> 38 39 #define DRV_NAME "sh-wdt" 40 41 /* 42 * Default clock division ratio is 5.25 msecs. For an additional table of 43 * values, consult the asm-sh/watchdog.h. Overload this at module load 44 * time. 45 * 46 * In order for this to work reliably we need to have HZ set to 1000 or 47 * something quite higher than 100 (or we need a proper high-res timer 48 * implementation that will deal with this properly), otherwise the 10ms 49 * resolution of a jiffy is enough to trigger the overflow. For things like 50 * the SH-4 and SH-5, this isn't necessarily that big of a problem, though 51 * for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely 52 * necssary. 53 * 54 * As a result of this timing problem, the only modes that are particularly 55 * feasible are the 4096 and the 2048 divisors, which yield 5.25 and 2.62ms 56 * overflow periods respectively. 57 * 58 * Also, since we can't really expect userspace to be responsive enough 59 * before the overflow happens, we maintain two separate timers .. One in 60 * the kernel for clearing out WOVF every 2ms or so (again, this depends on 61 * HZ == 1000), and another for monitoring userspace writes to the WDT device. 62 * 63 * As such, we currently use a configurable heartbeat interval which defaults 64 * to 30s. In this case, the userspace daemon is only responsible for periodic 65 * writes to the device before the next heartbeat is scheduled. If the daemon 66 * misses its deadline, the kernel timer will allow the WDT to overflow. 67 */ 68 static int clock_division_ratio = WTCSR_CKS_4096; 69 #define next_ping_period(cks) (jiffies + msecs_to_jiffies(cks - 4)) 70 71 #define WATCHDOG_HEARTBEAT 30 /* 30 sec default heartbeat */ 72 static int heartbeat = WATCHDOG_HEARTBEAT; /* in seconds */ 73 static bool nowayout = WATCHDOG_NOWAYOUT; 74 static unsigned long next_heartbeat; 75 76 struct sh_wdt { 77 void __iomem *base; 78 struct device *dev; 79 struct clk *clk; 80 spinlock_t lock; 81 82 struct timer_list timer; 83 }; 84 85 static int sh_wdt_start(struct watchdog_device *wdt_dev) 86 { 87 struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev); 88 unsigned long flags; 89 u8 csr; 90 91 pm_runtime_get_sync(wdt->dev); 92 clk_enable(wdt->clk); 93 94 spin_lock_irqsave(&wdt->lock, flags); 95 96 next_heartbeat = jiffies + (heartbeat * HZ); 97 mod_timer(&wdt->timer, next_ping_period(clock_division_ratio)); 98 99 csr = sh_wdt_read_csr(); 100 csr |= WTCSR_WT | clock_division_ratio; 101 sh_wdt_write_csr(csr); 102 103 sh_wdt_write_cnt(0); 104 105 /* 106 * These processors have a bit of an inconsistent initialization 107 * process.. starting with SH-3, RSTS was moved to WTCSR, and the 108 * RSTCSR register was removed. 109 * 110 * On the SH-2 however, in addition with bits being in different 111 * locations, we must deal with RSTCSR outright.. 112 */ 113 csr = sh_wdt_read_csr(); 114 csr |= WTCSR_TME; 115 csr &= ~WTCSR_RSTS; 116 sh_wdt_write_csr(csr); 117 118 #ifdef CONFIG_CPU_SH2 119 csr = sh_wdt_read_rstcsr(); 120 csr &= ~RSTCSR_RSTS; 121 sh_wdt_write_rstcsr(csr); 122 #endif 123 spin_unlock_irqrestore(&wdt->lock, flags); 124 125 return 0; 126 } 127 128 static int sh_wdt_stop(struct watchdog_device *wdt_dev) 129 { 130 struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev); 131 unsigned long flags; 132 u8 csr; 133 134 spin_lock_irqsave(&wdt->lock, flags); 135 136 del_timer(&wdt->timer); 137 138 csr = sh_wdt_read_csr(); 139 csr &= ~WTCSR_TME; 140 sh_wdt_write_csr(csr); 141 142 spin_unlock_irqrestore(&wdt->lock, flags); 143 144 clk_disable(wdt->clk); 145 pm_runtime_put_sync(wdt->dev); 146 147 return 0; 148 } 149 150 static int sh_wdt_keepalive(struct watchdog_device *wdt_dev) 151 { 152 struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev); 153 unsigned long flags; 154 155 spin_lock_irqsave(&wdt->lock, flags); 156 next_heartbeat = jiffies + (heartbeat * HZ); 157 spin_unlock_irqrestore(&wdt->lock, flags); 158 159 return 0; 160 } 161 162 static int sh_wdt_set_heartbeat(struct watchdog_device *wdt_dev, unsigned t) 163 { 164 struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev); 165 unsigned long flags; 166 167 if (unlikely(t < 1 || t > 3600)) /* arbitrary upper limit */ 168 return -EINVAL; 169 170 spin_lock_irqsave(&wdt->lock, flags); 171 heartbeat = t; 172 wdt_dev->timeout = t; 173 spin_unlock_irqrestore(&wdt->lock, flags); 174 175 return 0; 176 } 177 178 static void sh_wdt_ping(unsigned long data) 179 { 180 struct sh_wdt *wdt = (struct sh_wdt *)data; 181 unsigned long flags; 182 183 spin_lock_irqsave(&wdt->lock, flags); 184 if (time_before(jiffies, next_heartbeat)) { 185 u8 csr; 186 187 csr = sh_wdt_read_csr(); 188 csr &= ~WTCSR_IOVF; 189 sh_wdt_write_csr(csr); 190 191 sh_wdt_write_cnt(0); 192 193 mod_timer(&wdt->timer, next_ping_period(clock_division_ratio)); 194 } else 195 dev_warn(wdt->dev, "Heartbeat lost! Will not ping " 196 "the watchdog\n"); 197 spin_unlock_irqrestore(&wdt->lock, flags); 198 } 199 200 static const struct watchdog_info sh_wdt_info = { 201 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | 202 WDIOF_MAGICCLOSE, 203 .firmware_version = 1, 204 .identity = "SH WDT", 205 }; 206 207 static const struct watchdog_ops sh_wdt_ops = { 208 .owner = THIS_MODULE, 209 .start = sh_wdt_start, 210 .stop = sh_wdt_stop, 211 .ping = sh_wdt_keepalive, 212 .set_timeout = sh_wdt_set_heartbeat, 213 }; 214 215 static struct watchdog_device sh_wdt_dev = { 216 .info = &sh_wdt_info, 217 .ops = &sh_wdt_ops, 218 }; 219 220 static int sh_wdt_probe(struct platform_device *pdev) 221 { 222 struct sh_wdt *wdt; 223 struct resource *res; 224 int rc; 225 226 /* 227 * As this driver only covers the global watchdog case, reject 228 * any attempts to register per-CPU watchdogs. 229 */ 230 if (pdev->id != -1) 231 return -EINVAL; 232 233 wdt = devm_kzalloc(&pdev->dev, sizeof(struct sh_wdt), GFP_KERNEL); 234 if (unlikely(!wdt)) 235 return -ENOMEM; 236 237 wdt->dev = &pdev->dev; 238 239 wdt->clk = devm_clk_get(&pdev->dev, NULL); 240 if (IS_ERR(wdt->clk)) { 241 /* 242 * Clock framework support is optional, continue on 243 * anyways if we don't find a matching clock. 244 */ 245 wdt->clk = NULL; 246 } 247 248 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 249 wdt->base = devm_ioremap_resource(wdt->dev, res); 250 if (IS_ERR(wdt->base)) 251 return PTR_ERR(wdt->base); 252 253 watchdog_set_nowayout(&sh_wdt_dev, nowayout); 254 watchdog_set_drvdata(&sh_wdt_dev, wdt); 255 256 spin_lock_init(&wdt->lock); 257 258 rc = sh_wdt_set_heartbeat(&sh_wdt_dev, heartbeat); 259 if (unlikely(rc)) { 260 /* Default timeout if invalid */ 261 sh_wdt_set_heartbeat(&sh_wdt_dev, WATCHDOG_HEARTBEAT); 262 263 dev_warn(&pdev->dev, 264 "heartbeat value must be 1<=x<=3600, using %d\n", 265 sh_wdt_dev.timeout); 266 } 267 268 dev_info(&pdev->dev, "configured with heartbeat=%d sec (nowayout=%d)\n", 269 sh_wdt_dev.timeout, nowayout); 270 271 rc = watchdog_register_device(&sh_wdt_dev); 272 if (unlikely(rc)) { 273 dev_err(&pdev->dev, "Can't register watchdog (err=%d)\n", rc); 274 return rc; 275 } 276 277 init_timer(&wdt->timer); 278 wdt->timer.function = sh_wdt_ping; 279 wdt->timer.data = (unsigned long)wdt; 280 wdt->timer.expires = next_ping_period(clock_division_ratio); 281 282 dev_info(&pdev->dev, "initialized.\n"); 283 284 pm_runtime_enable(&pdev->dev); 285 286 return 0; 287 } 288 289 static int sh_wdt_remove(struct platform_device *pdev) 290 { 291 watchdog_unregister_device(&sh_wdt_dev); 292 293 pm_runtime_disable(&pdev->dev); 294 295 return 0; 296 } 297 298 static void sh_wdt_shutdown(struct platform_device *pdev) 299 { 300 sh_wdt_stop(&sh_wdt_dev); 301 } 302 303 static struct platform_driver sh_wdt_driver = { 304 .driver = { 305 .name = DRV_NAME, 306 }, 307 308 .probe = sh_wdt_probe, 309 .remove = sh_wdt_remove, 310 .shutdown = sh_wdt_shutdown, 311 }; 312 313 static int __init sh_wdt_init(void) 314 { 315 if (unlikely(clock_division_ratio < 0x5 || 316 clock_division_ratio > 0x7)) { 317 clock_division_ratio = WTCSR_CKS_4096; 318 319 pr_info("divisor must be 0x5<=x<=0x7, using %d\n", 320 clock_division_ratio); 321 } 322 323 return platform_driver_register(&sh_wdt_driver); 324 } 325 326 static void __exit sh_wdt_exit(void) 327 { 328 platform_driver_unregister(&sh_wdt_driver); 329 } 330 module_init(sh_wdt_init); 331 module_exit(sh_wdt_exit); 332 333 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>"); 334 MODULE_DESCRIPTION("SuperH watchdog driver"); 335 MODULE_LICENSE("GPL"); 336 MODULE_ALIAS("platform:" DRV_NAME); 337 338 module_param(clock_division_ratio, int, 0); 339 MODULE_PARM_DESC(clock_division_ratio, 340 "Clock division ratio. Valid ranges are from 0x5 (1.31ms) " 341 "to 0x7 (5.25ms). (default=" __MODULE_STRING(WTCSR_CKS_4096) ")"); 342 343 module_param(heartbeat, int, 0); 344 MODULE_PARM_DESC(heartbeat, 345 "Watchdog heartbeat in seconds. (1 <= heartbeat <= 3600, default=" 346 __MODULE_STRING(WATCHDOG_HEARTBEAT) ")"); 347 348 module_param(nowayout, bool, 0); 349 MODULE_PARM_DESC(nowayout, 350 "Watchdog cannot be stopped once started (default=" 351 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 352