1 /* 2 * Watchdog driver for IMX2 and later processors 3 * 4 * Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <w.sang@pengutronix.de> 5 * 6 * some parts adapted by similar drivers from Darius Augulis and Vladimir 7 * Zapolskiy, additional improvements by Wim Van Sebroeck. 8 * 9 * This program is free software; you can redistribute it and/or modify it 10 * under the terms of the GNU General Public License version 2 as published by 11 * the Free Software Foundation. 12 * 13 * NOTE: MX1 has a slightly different Watchdog than MX2 and later: 14 * 15 * MX1: MX2+: 16 * ---- ----- 17 * Registers: 32-bit 16-bit 18 * Stopable timer: Yes No 19 * Need to enable clk: No Yes 20 * Halt on suspend: Manual Can be automatic 21 */ 22 23 #include <linux/init.h> 24 #include <linux/kernel.h> 25 #include <linux/miscdevice.h> 26 #include <linux/module.h> 27 #include <linux/moduleparam.h> 28 #include <linux/platform_device.h> 29 #include <linux/watchdog.h> 30 #include <linux/clk.h> 31 #include <linux/fs.h> 32 #include <linux/io.h> 33 #include <linux/uaccess.h> 34 #include <linux/timer.h> 35 #include <linux/jiffies.h> 36 #include <mach/hardware.h> 37 38 #define DRIVER_NAME "imx2-wdt" 39 40 #define IMX2_WDT_WCR 0x00 /* Control Register */ 41 #define IMX2_WDT_WCR_WT (0xFF << 8) /* -> Watchdog Timeout Field */ 42 #define IMX2_WDT_WCR_WRE (1 << 3) /* -> WDOG Reset Enable */ 43 #define IMX2_WDT_WCR_WDE (1 << 2) /* -> Watchdog Enable */ 44 45 #define IMX2_WDT_WSR 0x02 /* Service Register */ 46 #define IMX2_WDT_SEQ1 0x5555 /* -> service sequence 1 */ 47 #define IMX2_WDT_SEQ2 0xAAAA /* -> service sequence 2 */ 48 49 #define IMX2_WDT_MAX_TIME 128 50 #define IMX2_WDT_DEFAULT_TIME 60 /* in seconds */ 51 52 #define WDOG_SEC_TO_COUNT(s) ((s * 2 - 1) << 8) 53 54 #define IMX2_WDT_STATUS_OPEN 0 55 #define IMX2_WDT_STATUS_STARTED 1 56 #define IMX2_WDT_EXPECT_CLOSE 2 57 58 static struct { 59 struct clk *clk; 60 void __iomem *base; 61 unsigned timeout; 62 unsigned long status; 63 struct timer_list timer; /* Pings the watchdog when closed */ 64 } imx2_wdt; 65 66 static struct miscdevice imx2_wdt_miscdev; 67 68 static int nowayout = WATCHDOG_NOWAYOUT; 69 module_param(nowayout, int, 0); 70 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 71 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 72 73 74 static unsigned timeout = IMX2_WDT_DEFAULT_TIME; 75 module_param(timeout, uint, 0); 76 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default=" 77 __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")"); 78 79 static const struct watchdog_info imx2_wdt_info = { 80 .identity = "imx2+ watchdog", 81 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, 82 }; 83 84 static inline void imx2_wdt_setup(void) 85 { 86 u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR); 87 88 /* Strip the old watchdog Time-Out value */ 89 val &= ~IMX2_WDT_WCR_WT; 90 /* Generate reset if WDOG times out */ 91 val &= ~IMX2_WDT_WCR_WRE; 92 /* Keep Watchdog Disabled */ 93 val &= ~IMX2_WDT_WCR_WDE; 94 /* Set the watchdog's Time-Out value */ 95 val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout); 96 97 __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR); 98 99 /* enable the watchdog */ 100 val |= IMX2_WDT_WCR_WDE; 101 __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR); 102 } 103 104 static inline void imx2_wdt_ping(void) 105 { 106 __raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR); 107 __raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR); 108 } 109 110 static void imx2_wdt_timer_ping(unsigned long arg) 111 { 112 /* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */ 113 imx2_wdt_ping(); 114 mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2); 115 } 116 117 static void imx2_wdt_start(void) 118 { 119 if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) { 120 /* at our first start we enable clock and do initialisations */ 121 clk_enable(imx2_wdt.clk); 122 123 imx2_wdt_setup(); 124 } else /* delete the timer that pings the watchdog after close */ 125 del_timer_sync(&imx2_wdt.timer); 126 127 /* Watchdog is enabled - time to reload the timeout value */ 128 imx2_wdt_ping(); 129 } 130 131 static void imx2_wdt_stop(void) 132 { 133 /* we don't need a clk_disable, it cannot be disabled once started. 134 * We use a timer to ping the watchdog while /dev/watchdog is closed */ 135 imx2_wdt_timer_ping(0); 136 } 137 138 static void imx2_wdt_set_timeout(int new_timeout) 139 { 140 u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR); 141 142 /* set the new timeout value in the WSR */ 143 val &= ~IMX2_WDT_WCR_WT; 144 val |= WDOG_SEC_TO_COUNT(new_timeout); 145 __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR); 146 } 147 148 static int imx2_wdt_open(struct inode *inode, struct file *file) 149 { 150 if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status)) 151 return -EBUSY; 152 153 imx2_wdt_start(); 154 return nonseekable_open(inode, file); 155 } 156 157 static int imx2_wdt_close(struct inode *inode, struct file *file) 158 { 159 if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout) 160 imx2_wdt_stop(); 161 else { 162 dev_crit(imx2_wdt_miscdev.parent, 163 "Unexpected close: Expect reboot!\n"); 164 imx2_wdt_ping(); 165 } 166 167 clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status); 168 clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status); 169 return 0; 170 } 171 172 static long imx2_wdt_ioctl(struct file *file, unsigned int cmd, 173 unsigned long arg) 174 { 175 void __user *argp = (void __user *)arg; 176 int __user *p = argp; 177 int new_value; 178 179 switch (cmd) { 180 case WDIOC_GETSUPPORT: 181 return copy_to_user(argp, &imx2_wdt_info, 182 sizeof(struct watchdog_info)) ? -EFAULT : 0; 183 184 case WDIOC_GETSTATUS: 185 case WDIOC_GETBOOTSTATUS: 186 return put_user(0, p); 187 188 case WDIOC_KEEPALIVE: 189 imx2_wdt_ping(); 190 return 0; 191 192 case WDIOC_SETTIMEOUT: 193 if (get_user(new_value, p)) 194 return -EFAULT; 195 if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME)) 196 return -EINVAL; 197 imx2_wdt_set_timeout(new_value); 198 imx2_wdt.timeout = new_value; 199 imx2_wdt_ping(); 200 201 /* Fallthrough to return current value */ 202 case WDIOC_GETTIMEOUT: 203 return put_user(imx2_wdt.timeout, p); 204 205 default: 206 return -ENOTTY; 207 } 208 } 209 210 static ssize_t imx2_wdt_write(struct file *file, const char __user *data, 211 size_t len, loff_t *ppos) 212 { 213 size_t i; 214 char c; 215 216 if (len == 0) /* Can we see this even ? */ 217 return 0; 218 219 clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status); 220 /* scan to see whether or not we got the magic character */ 221 for (i = 0; i != len; i++) { 222 if (get_user(c, data + i)) 223 return -EFAULT; 224 if (c == 'V') 225 set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status); 226 } 227 228 imx2_wdt_ping(); 229 return len; 230 } 231 232 static const struct file_operations imx2_wdt_fops = { 233 .owner = THIS_MODULE, 234 .llseek = no_llseek, 235 .unlocked_ioctl = imx2_wdt_ioctl, 236 .open = imx2_wdt_open, 237 .release = imx2_wdt_close, 238 .write = imx2_wdt_write, 239 }; 240 241 static struct miscdevice imx2_wdt_miscdev = { 242 .minor = WATCHDOG_MINOR, 243 .name = "watchdog", 244 .fops = &imx2_wdt_fops, 245 }; 246 247 static int __init imx2_wdt_probe(struct platform_device *pdev) 248 { 249 int ret; 250 int res_size; 251 struct resource *res; 252 253 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 254 if (!res) { 255 dev_err(&pdev->dev, "can't get device resources\n"); 256 return -ENODEV; 257 } 258 259 res_size = resource_size(res); 260 if (!devm_request_mem_region(&pdev->dev, res->start, res_size, 261 res->name)) { 262 dev_err(&pdev->dev, "can't allocate %d bytes at %d address\n", 263 res_size, res->start); 264 return -ENOMEM; 265 } 266 267 imx2_wdt.base = devm_ioremap_nocache(&pdev->dev, res->start, res_size); 268 if (!imx2_wdt.base) { 269 dev_err(&pdev->dev, "ioremap failed\n"); 270 return -ENOMEM; 271 } 272 273 imx2_wdt.clk = clk_get(&pdev->dev, NULL); 274 if (IS_ERR(imx2_wdt.clk)) { 275 dev_err(&pdev->dev, "can't get Watchdog clock\n"); 276 return PTR_ERR(imx2_wdt.clk); 277 } 278 279 imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME); 280 if (imx2_wdt.timeout != timeout) 281 dev_warn(&pdev->dev, "Initial timeout out of range! " 282 "Clamped from %u to %u\n", timeout, imx2_wdt.timeout); 283 284 setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0); 285 286 imx2_wdt_miscdev.parent = &pdev->dev; 287 ret = misc_register(&imx2_wdt_miscdev); 288 if (ret) 289 goto fail; 290 291 dev_info(&pdev->dev, 292 "IMX2+ Watchdog Timer enabled. timeout=%ds (nowayout=%d)\n", 293 imx2_wdt.timeout, nowayout); 294 return 0; 295 296 fail: 297 imx2_wdt_miscdev.parent = NULL; 298 clk_put(imx2_wdt.clk); 299 return ret; 300 } 301 302 static int __exit imx2_wdt_remove(struct platform_device *pdev) 303 { 304 misc_deregister(&imx2_wdt_miscdev); 305 306 if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) { 307 del_timer_sync(&imx2_wdt.timer); 308 309 dev_crit(imx2_wdt_miscdev.parent, 310 "Device removed: Expect reboot!\n"); 311 } else 312 clk_put(imx2_wdt.clk); 313 314 imx2_wdt_miscdev.parent = NULL; 315 return 0; 316 } 317 318 static void imx2_wdt_shutdown(struct platform_device *pdev) 319 { 320 if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) { 321 /* we are running, we need to delete the timer but will give 322 * max timeout before reboot will take place */ 323 del_timer_sync(&imx2_wdt.timer); 324 imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME); 325 imx2_wdt_ping(); 326 327 dev_crit(imx2_wdt_miscdev.parent, 328 "Device shutdown: Expect reboot!\n"); 329 } 330 } 331 332 static struct platform_driver imx2_wdt_driver = { 333 .remove = __exit_p(imx2_wdt_remove), 334 .shutdown = imx2_wdt_shutdown, 335 .driver = { 336 .name = DRIVER_NAME, 337 .owner = THIS_MODULE, 338 }, 339 }; 340 341 static int __init imx2_wdt_init(void) 342 { 343 return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe); 344 } 345 module_init(imx2_wdt_init); 346 347 static void __exit imx2_wdt_exit(void) 348 { 349 platform_driver_unregister(&imx2_wdt_driver); 350 } 351 module_exit(imx2_wdt_exit); 352 353 MODULE_AUTHOR("Wolfram Sang"); 354 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later"); 355 MODULE_LICENSE("GPL v2"); 356 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 357 MODULE_ALIAS("platform:" DRIVER_NAME); 358