1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Watchdog driver for IMX2 and later processors 4 * 5 * Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <w.sang@pengutronix.de> 6 * Copyright (C) 2014 Freescale Semiconductor, Inc. 7 * 8 * some parts adapted by similar drivers from Darius Augulis and Vladimir 9 * Zapolskiy, additional improvements by Wim Van Sebroeck. 10 * 11 * NOTE: MX1 has a slightly different Watchdog than MX2 and later: 12 * 13 * MX1: MX2+: 14 * ---- ----- 15 * Registers: 32-bit 16-bit 16 * Stopable timer: Yes No 17 * Need to enable clk: No Yes 18 * Halt on suspend: Manual Can be automatic 19 */ 20 21 #include <linux/clk.h> 22 #include <linux/delay.h> 23 #include <linux/init.h> 24 #include <linux/interrupt.h> 25 #include <linux/io.h> 26 #include <linux/kernel.h> 27 #include <linux/module.h> 28 #include <linux/moduleparam.h> 29 #include <linux/of_address.h> 30 #include <linux/platform_device.h> 31 #include <linux/regmap.h> 32 #include <linux/watchdog.h> 33 34 #define DRIVER_NAME "imx2-wdt" 35 36 #define IMX2_WDT_WCR 0x00 /* Control Register */ 37 #define IMX2_WDT_WCR_WT (0xFF << 8) /* -> Watchdog Timeout Field */ 38 #define IMX2_WDT_WCR_WDA BIT(5) /* -> External Reset WDOG_B */ 39 #define IMX2_WDT_WCR_SRS BIT(4) /* -> Software Reset Signal */ 40 #define IMX2_WDT_WCR_WRE BIT(3) /* -> WDOG Reset Enable */ 41 #define IMX2_WDT_WCR_WDE BIT(2) /* -> Watchdog Enable */ 42 #define IMX2_WDT_WCR_WDZST BIT(0) /* -> Watchdog timer Suspend */ 43 44 #define IMX2_WDT_WSR 0x02 /* Service Register */ 45 #define IMX2_WDT_SEQ1 0x5555 /* -> service sequence 1 */ 46 #define IMX2_WDT_SEQ2 0xAAAA /* -> service sequence 2 */ 47 48 #define IMX2_WDT_WRSR 0x04 /* Reset Status Register */ 49 #define IMX2_WDT_WRSR_TOUT BIT(1) /* -> Reset due to Timeout */ 50 51 #define IMX2_WDT_WICR 0x06 /* Interrupt Control Register */ 52 #define IMX2_WDT_WICR_WIE BIT(15) /* -> Interrupt Enable */ 53 #define IMX2_WDT_WICR_WTIS BIT(14) /* -> Interrupt Status */ 54 #define IMX2_WDT_WICR_WICT 0xFF /* -> Interrupt Count Timeout */ 55 56 #define IMX2_WDT_WMCR 0x08 /* Misc Register */ 57 58 #define IMX2_WDT_MAX_TIME 128U 59 #define IMX2_WDT_DEFAULT_TIME 60 /* in seconds */ 60 61 #define WDOG_SEC_TO_COUNT(s) ((s * 2 - 1) << 8) 62 63 struct imx2_wdt_device { 64 struct clk *clk; 65 struct regmap *regmap; 66 struct watchdog_device wdog; 67 bool ext_reset; 68 }; 69 70 static bool nowayout = WATCHDOG_NOWAYOUT; 71 module_param(nowayout, bool, 0); 72 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 73 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 74 75 static unsigned timeout; 76 module_param(timeout, uint, 0); 77 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default=" 78 __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")"); 79 80 static const struct watchdog_info imx2_wdt_info = { 81 .identity = "imx2+ watchdog", 82 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, 83 }; 84 85 static const struct watchdog_info imx2_wdt_pretimeout_info = { 86 .identity = "imx2+ watchdog", 87 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | 88 WDIOF_PRETIMEOUT, 89 }; 90 91 static int imx2_wdt_restart(struct watchdog_device *wdog, unsigned long action, 92 void *data) 93 { 94 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog); 95 unsigned int wcr_enable = IMX2_WDT_WCR_WDE; 96 97 /* Use internal reset or external - not both */ 98 if (wdev->ext_reset) 99 wcr_enable |= IMX2_WDT_WCR_SRS; /* do not assert int reset */ 100 else 101 wcr_enable |= IMX2_WDT_WCR_WDA; /* do not assert ext-reset */ 102 103 /* Assert SRS signal */ 104 regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable); 105 /* 106 * Due to imx6q errata ERR004346 (WDOG: WDOG SRS bit requires to be 107 * written twice), we add another two writes to ensure there must be at 108 * least two writes happen in the same one 32kHz clock period. We save 109 * the target check here, since the writes shouldn't be a huge burden 110 * for other platforms. 111 */ 112 regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable); 113 regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable); 114 115 /* wait for reset to assert... */ 116 mdelay(500); 117 118 return 0; 119 } 120 121 static inline void imx2_wdt_setup(struct watchdog_device *wdog) 122 { 123 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog); 124 u32 val; 125 126 regmap_read(wdev->regmap, IMX2_WDT_WCR, &val); 127 128 /* Suspend timer in low power mode, write once-only */ 129 val |= IMX2_WDT_WCR_WDZST; 130 /* Strip the old watchdog Time-Out value */ 131 val &= ~IMX2_WDT_WCR_WT; 132 /* Generate internal chip-level reset if WDOG times out */ 133 if (!wdev->ext_reset) 134 val &= ~IMX2_WDT_WCR_WRE; 135 /* Or if external-reset assert WDOG_B reset only on time-out */ 136 else 137 val |= IMX2_WDT_WCR_WRE; 138 /* Keep Watchdog Disabled */ 139 val &= ~IMX2_WDT_WCR_WDE; 140 /* Set the watchdog's Time-Out value */ 141 val |= WDOG_SEC_TO_COUNT(wdog->timeout); 142 143 regmap_write(wdev->regmap, IMX2_WDT_WCR, val); 144 145 /* enable the watchdog */ 146 val |= IMX2_WDT_WCR_WDE; 147 regmap_write(wdev->regmap, IMX2_WDT_WCR, val); 148 } 149 150 static inline bool imx2_wdt_is_running(struct imx2_wdt_device *wdev) 151 { 152 u32 val; 153 154 regmap_read(wdev->regmap, IMX2_WDT_WCR, &val); 155 156 return val & IMX2_WDT_WCR_WDE; 157 } 158 159 static int imx2_wdt_ping(struct watchdog_device *wdog) 160 { 161 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog); 162 163 regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1); 164 regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2); 165 return 0; 166 } 167 168 static void __imx2_wdt_set_timeout(struct watchdog_device *wdog, 169 unsigned int new_timeout) 170 { 171 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog); 172 173 regmap_update_bits(wdev->regmap, IMX2_WDT_WCR, IMX2_WDT_WCR_WT, 174 WDOG_SEC_TO_COUNT(new_timeout)); 175 } 176 177 static int imx2_wdt_set_timeout(struct watchdog_device *wdog, 178 unsigned int new_timeout) 179 { 180 unsigned int actual; 181 182 actual = min(new_timeout, IMX2_WDT_MAX_TIME); 183 __imx2_wdt_set_timeout(wdog, actual); 184 wdog->timeout = new_timeout; 185 return 0; 186 } 187 188 static int imx2_wdt_set_pretimeout(struct watchdog_device *wdog, 189 unsigned int new_pretimeout) 190 { 191 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog); 192 193 if (new_pretimeout >= IMX2_WDT_MAX_TIME) 194 return -EINVAL; 195 196 wdog->pretimeout = new_pretimeout; 197 198 regmap_update_bits(wdev->regmap, IMX2_WDT_WICR, 199 IMX2_WDT_WICR_WIE | IMX2_WDT_WICR_WICT, 200 IMX2_WDT_WICR_WIE | (new_pretimeout << 1)); 201 return 0; 202 } 203 204 static irqreturn_t imx2_wdt_isr(int irq, void *wdog_arg) 205 { 206 struct watchdog_device *wdog = wdog_arg; 207 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog); 208 209 regmap_write_bits(wdev->regmap, IMX2_WDT_WICR, 210 IMX2_WDT_WICR_WTIS, IMX2_WDT_WICR_WTIS); 211 212 watchdog_notify_pretimeout(wdog); 213 214 return IRQ_HANDLED; 215 } 216 217 static int imx2_wdt_start(struct watchdog_device *wdog) 218 { 219 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog); 220 221 if (imx2_wdt_is_running(wdev)) 222 imx2_wdt_set_timeout(wdog, wdog->timeout); 223 else 224 imx2_wdt_setup(wdog); 225 226 set_bit(WDOG_HW_RUNNING, &wdog->status); 227 228 return imx2_wdt_ping(wdog); 229 } 230 231 static const struct watchdog_ops imx2_wdt_ops = { 232 .owner = THIS_MODULE, 233 .start = imx2_wdt_start, 234 .ping = imx2_wdt_ping, 235 .set_timeout = imx2_wdt_set_timeout, 236 .set_pretimeout = imx2_wdt_set_pretimeout, 237 .restart = imx2_wdt_restart, 238 }; 239 240 static const struct regmap_config imx2_wdt_regmap_config = { 241 .reg_bits = 16, 242 .reg_stride = 2, 243 .val_bits = 16, 244 .max_register = 0x8, 245 }; 246 247 static void imx2_wdt_action(void *data) 248 { 249 clk_disable_unprepare(data); 250 } 251 252 static int __init imx2_wdt_probe(struct platform_device *pdev) 253 { 254 struct device *dev = &pdev->dev; 255 struct imx2_wdt_device *wdev; 256 struct watchdog_device *wdog; 257 void __iomem *base; 258 int ret; 259 u32 val; 260 261 wdev = devm_kzalloc(dev, sizeof(*wdev), GFP_KERNEL); 262 if (!wdev) 263 return -ENOMEM; 264 265 base = devm_platform_ioremap_resource(pdev, 0); 266 if (IS_ERR(base)) 267 return PTR_ERR(base); 268 269 wdev->regmap = devm_regmap_init_mmio_clk(dev, NULL, base, 270 &imx2_wdt_regmap_config); 271 if (IS_ERR(wdev->regmap)) { 272 dev_err(dev, "regmap init failed\n"); 273 return PTR_ERR(wdev->regmap); 274 } 275 276 wdev->clk = devm_clk_get(dev, NULL); 277 if (IS_ERR(wdev->clk)) { 278 dev_err(dev, "can't get Watchdog clock\n"); 279 return PTR_ERR(wdev->clk); 280 } 281 282 wdog = &wdev->wdog; 283 wdog->info = &imx2_wdt_info; 284 wdog->ops = &imx2_wdt_ops; 285 wdog->min_timeout = 1; 286 wdog->timeout = IMX2_WDT_DEFAULT_TIME; 287 wdog->max_hw_heartbeat_ms = IMX2_WDT_MAX_TIME * 1000; 288 wdog->parent = dev; 289 290 ret = platform_get_irq(pdev, 0); 291 if (ret > 0) 292 if (!devm_request_irq(dev, ret, imx2_wdt_isr, 0, 293 dev_name(dev), wdog)) 294 wdog->info = &imx2_wdt_pretimeout_info; 295 296 ret = clk_prepare_enable(wdev->clk); 297 if (ret) 298 return ret; 299 300 ret = devm_add_action_or_reset(dev, imx2_wdt_action, wdev->clk); 301 if (ret) 302 return ret; 303 304 regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val); 305 wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0; 306 307 wdev->ext_reset = of_property_read_bool(dev->of_node, 308 "fsl,ext-reset-output"); 309 platform_set_drvdata(pdev, wdog); 310 watchdog_set_drvdata(wdog, wdev); 311 watchdog_set_nowayout(wdog, nowayout); 312 watchdog_set_restart_priority(wdog, 128); 313 watchdog_init_timeout(wdog, timeout, dev); 314 315 if (imx2_wdt_is_running(wdev)) { 316 imx2_wdt_set_timeout(wdog, wdog->timeout); 317 set_bit(WDOG_HW_RUNNING, &wdog->status); 318 } 319 320 /* 321 * Disable the watchdog power down counter at boot. Otherwise the power 322 * down counter will pull down the #WDOG interrupt line for one clock 323 * cycle. 324 */ 325 regmap_write(wdev->regmap, IMX2_WDT_WMCR, 0); 326 327 return devm_watchdog_register_device(dev, wdog); 328 } 329 330 static void imx2_wdt_shutdown(struct platform_device *pdev) 331 { 332 struct watchdog_device *wdog = platform_get_drvdata(pdev); 333 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog); 334 335 if (imx2_wdt_is_running(wdev)) { 336 /* 337 * We are running, configure max timeout before reboot 338 * will take place. 339 */ 340 imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME); 341 imx2_wdt_ping(wdog); 342 dev_crit(&pdev->dev, "Device shutdown: Expect reboot!\n"); 343 } 344 } 345 346 /* Disable watchdog if it is active or non-active but still running */ 347 static int __maybe_unused imx2_wdt_suspend(struct device *dev) 348 { 349 struct watchdog_device *wdog = dev_get_drvdata(dev); 350 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog); 351 352 /* The watchdog IP block is running */ 353 if (imx2_wdt_is_running(wdev)) { 354 /* 355 * Don't update wdog->timeout, we'll restore the current value 356 * during resume. 357 */ 358 __imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME); 359 imx2_wdt_ping(wdog); 360 } 361 362 clk_disable_unprepare(wdev->clk); 363 364 return 0; 365 } 366 367 /* Enable watchdog and configure it if necessary */ 368 static int __maybe_unused imx2_wdt_resume(struct device *dev) 369 { 370 struct watchdog_device *wdog = dev_get_drvdata(dev); 371 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog); 372 int ret; 373 374 ret = clk_prepare_enable(wdev->clk); 375 if (ret) 376 return ret; 377 378 if (watchdog_active(wdog) && !imx2_wdt_is_running(wdev)) { 379 /* 380 * If the watchdog is still active and resumes 381 * from deep sleep state, need to restart the 382 * watchdog again. 383 */ 384 imx2_wdt_setup(wdog); 385 } 386 if (imx2_wdt_is_running(wdev)) { 387 imx2_wdt_set_timeout(wdog, wdog->timeout); 388 imx2_wdt_ping(wdog); 389 } 390 391 return 0; 392 } 393 394 static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend, 395 imx2_wdt_resume); 396 397 static const struct of_device_id imx2_wdt_dt_ids[] = { 398 { .compatible = "fsl,imx21-wdt", }, 399 { /* sentinel */ } 400 }; 401 MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids); 402 403 static struct platform_driver imx2_wdt_driver = { 404 .shutdown = imx2_wdt_shutdown, 405 .driver = { 406 .name = DRIVER_NAME, 407 .pm = &imx2_wdt_pm_ops, 408 .of_match_table = imx2_wdt_dt_ids, 409 }, 410 }; 411 412 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe); 413 414 MODULE_AUTHOR("Wolfram Sang"); 415 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later"); 416 MODULE_LICENSE("GPL v2"); 417 MODULE_ALIAS("platform:" DRIVER_NAME); 418