1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Driver for Atmel SAMA5D4 Watchdog Timer 4 * 5 * Copyright (C) 2015-2019 Microchip Technology Inc. and its subsidiaries 6 */ 7 8 #include <linux/delay.h> 9 #include <linux/interrupt.h> 10 #include <linux/io.h> 11 #include <linux/kernel.h> 12 #include <linux/module.h> 13 #include <linux/of.h> 14 #include <linux/of_device.h> 15 #include <linux/of_irq.h> 16 #include <linux/platform_device.h> 17 #include <linux/reboot.h> 18 #include <linux/watchdog.h> 19 20 #include "at91sam9_wdt.h" 21 22 /* minimum and maximum watchdog timeout, in seconds */ 23 #define MIN_WDT_TIMEOUT 1 24 #define MAX_WDT_TIMEOUT 16 25 #define WDT_DEFAULT_TIMEOUT MAX_WDT_TIMEOUT 26 27 #define WDT_SEC2TICKS(s) ((s) ? (((s) << 8) - 1) : 0) 28 29 struct sama5d4_wdt { 30 struct watchdog_device wdd; 31 void __iomem *reg_base; 32 u32 mr; 33 u32 ir; 34 unsigned long last_ping; 35 bool need_irq; 36 bool sam9x60_support; 37 }; 38 39 static int wdt_timeout; 40 static bool nowayout = WATCHDOG_NOWAYOUT; 41 42 module_param(wdt_timeout, int, 0); 43 MODULE_PARM_DESC(wdt_timeout, 44 "Watchdog timeout in seconds. (default = " 45 __MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")"); 46 47 module_param(nowayout, bool, 0); 48 MODULE_PARM_DESC(nowayout, 49 "Watchdog cannot be stopped once started (default=" 50 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 51 52 #define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS)) 53 54 #define wdt_read(wdt, field) \ 55 readl_relaxed((wdt)->reg_base + (field)) 56 57 /* 4 slow clock periods is 4/32768 = 122.07µs*/ 58 #define WDT_DELAY usecs_to_jiffies(123) 59 60 static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val) 61 { 62 /* 63 * WDT_CR and WDT_MR must not be modified within three slow clock 64 * periods following a restart of the watchdog performed by a write 65 * access in WDT_CR. 66 */ 67 while (time_before(jiffies, wdt->last_ping + WDT_DELAY)) 68 usleep_range(30, 125); 69 writel_relaxed(val, wdt->reg_base + field); 70 wdt->last_ping = jiffies; 71 } 72 73 static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val) 74 { 75 if (time_before(jiffies, wdt->last_ping + WDT_DELAY)) 76 udelay(123); 77 writel_relaxed(val, wdt->reg_base + field); 78 wdt->last_ping = jiffies; 79 } 80 81 static int sama5d4_wdt_start(struct watchdog_device *wdd) 82 { 83 struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd); 84 85 if (wdt->sam9x60_support) { 86 writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IER); 87 wdt->mr &= ~AT91_SAM9X60_WDDIS; 88 } else { 89 wdt->mr &= ~AT91_WDT_WDDIS; 90 } 91 wdt_write(wdt, AT91_WDT_MR, wdt->mr); 92 93 return 0; 94 } 95 96 static int sama5d4_wdt_stop(struct watchdog_device *wdd) 97 { 98 struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd); 99 100 if (wdt->sam9x60_support) { 101 writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IDR); 102 wdt->mr |= AT91_SAM9X60_WDDIS; 103 } else { 104 wdt->mr |= AT91_WDT_WDDIS; 105 } 106 wdt_write(wdt, AT91_WDT_MR, wdt->mr); 107 108 return 0; 109 } 110 111 static int sama5d4_wdt_ping(struct watchdog_device *wdd) 112 { 113 struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd); 114 115 wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT); 116 117 return 0; 118 } 119 120 static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd, 121 unsigned int timeout) 122 { 123 struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd); 124 u32 value = WDT_SEC2TICKS(timeout); 125 126 if (wdt->sam9x60_support) { 127 wdt_write(wdt, AT91_SAM9X60_WLR, 128 AT91_SAM9X60_SET_COUNTER(value)); 129 130 wdd->timeout = timeout; 131 return 0; 132 } 133 134 wdt->mr &= ~AT91_WDT_WDV; 135 wdt->mr |= AT91_WDT_SET_WDV(value); 136 137 /* 138 * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When 139 * setting the WDDIS bit, and while it is set, the fields WDV and WDD 140 * must not be modified. 141 * If the watchdog is enabled, then the timeout can be updated. Else, 142 * wait that the user enables it. 143 */ 144 if (wdt_enabled) 145 wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS); 146 147 wdd->timeout = timeout; 148 149 return 0; 150 } 151 152 static const struct watchdog_info sama5d4_wdt_info = { 153 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING, 154 .identity = "Atmel SAMA5D4 Watchdog", 155 }; 156 157 static const struct watchdog_ops sama5d4_wdt_ops = { 158 .owner = THIS_MODULE, 159 .start = sama5d4_wdt_start, 160 .stop = sama5d4_wdt_stop, 161 .ping = sama5d4_wdt_ping, 162 .set_timeout = sama5d4_wdt_set_timeout, 163 }; 164 165 static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id) 166 { 167 struct sama5d4_wdt *wdt = platform_get_drvdata(dev_id); 168 u32 reg; 169 170 if (wdt->sam9x60_support) 171 reg = wdt_read(wdt, AT91_SAM9X60_ISR); 172 else 173 reg = wdt_read(wdt, AT91_WDT_SR); 174 175 if (reg) { 176 pr_crit("Atmel Watchdog Software Reset\n"); 177 emergency_restart(); 178 pr_crit("Reboot didn't succeed\n"); 179 } 180 181 return IRQ_HANDLED; 182 } 183 184 static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt) 185 { 186 const char *tmp; 187 188 if (wdt->sam9x60_support) 189 wdt->mr = AT91_SAM9X60_WDDIS; 190 else 191 wdt->mr = AT91_WDT_WDDIS; 192 193 if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) && 194 !strcmp(tmp, "software")) 195 wdt->need_irq = true; 196 197 if (of_property_read_bool(np, "atmel,idle-halt")) 198 wdt->mr |= AT91_WDT_WDIDLEHLT; 199 200 if (of_property_read_bool(np, "atmel,dbg-halt")) 201 wdt->mr |= AT91_WDT_WDDBGHLT; 202 203 return 0; 204 } 205 206 static int sama5d4_wdt_init(struct sama5d4_wdt *wdt) 207 { 208 u32 reg, val; 209 210 val = WDT_SEC2TICKS(WDT_DEFAULT_TIMEOUT); 211 /* 212 * When booting and resuming, the bootloader may have changed the 213 * watchdog configuration. 214 * If the watchdog is already running, we can safely update it. 215 * Else, we have to disable it properly. 216 */ 217 if (!wdt_enabled) { 218 reg = wdt_read(wdt, AT91_WDT_MR); 219 if (wdt->sam9x60_support && (!(reg & AT91_SAM9X60_WDDIS))) 220 wdt_write_nosleep(wdt, AT91_WDT_MR, 221 reg | AT91_SAM9X60_WDDIS); 222 else if (!wdt->sam9x60_support && 223 (!(reg & AT91_WDT_WDDIS))) 224 wdt_write_nosleep(wdt, AT91_WDT_MR, 225 reg | AT91_WDT_WDDIS); 226 } 227 228 if (wdt->sam9x60_support) { 229 if (wdt->need_irq) 230 wdt->ir = AT91_SAM9X60_PERINT; 231 else 232 wdt->mr |= AT91_SAM9X60_PERIODRST; 233 234 wdt_write(wdt, AT91_SAM9X60_IER, wdt->ir); 235 wdt_write(wdt, AT91_SAM9X60_WLR, AT91_SAM9X60_SET_COUNTER(val)); 236 } else { 237 wdt->mr |= AT91_WDT_SET_WDD(WDT_SEC2TICKS(MAX_WDT_TIMEOUT)); 238 wdt->mr |= AT91_WDT_SET_WDV(val); 239 240 if (wdt->need_irq) 241 wdt->mr |= AT91_WDT_WDFIEN; 242 else 243 wdt->mr |= AT91_WDT_WDRSTEN; 244 } 245 246 wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr); 247 248 return 0; 249 } 250 251 static int sama5d4_wdt_probe(struct platform_device *pdev) 252 { 253 struct device *dev = &pdev->dev; 254 struct watchdog_device *wdd; 255 struct sama5d4_wdt *wdt; 256 void __iomem *regs; 257 u32 irq = 0; 258 int ret; 259 260 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 261 if (!wdt) 262 return -ENOMEM; 263 264 wdd = &wdt->wdd; 265 wdd->timeout = WDT_DEFAULT_TIMEOUT; 266 wdd->info = &sama5d4_wdt_info; 267 wdd->ops = &sama5d4_wdt_ops; 268 wdd->min_timeout = MIN_WDT_TIMEOUT; 269 wdd->max_timeout = MAX_WDT_TIMEOUT; 270 wdt->last_ping = jiffies; 271 272 if (of_device_is_compatible(dev->of_node, "microchip,sam9x60-wdt") || 273 of_device_is_compatible(dev->of_node, "microchip,sama7g5-wdt")) 274 wdt->sam9x60_support = true; 275 276 watchdog_set_drvdata(wdd, wdt); 277 278 regs = devm_platform_ioremap_resource(pdev, 0); 279 if (IS_ERR(regs)) 280 return PTR_ERR(regs); 281 282 wdt->reg_base = regs; 283 284 ret = of_sama5d4_wdt_init(dev->of_node, wdt); 285 if (ret) 286 return ret; 287 288 if (wdt->need_irq) { 289 irq = irq_of_parse_and_map(dev->of_node, 0); 290 if (!irq) { 291 dev_warn(dev, "failed to get IRQ from DT\n"); 292 wdt->need_irq = false; 293 } 294 } 295 296 if (wdt->need_irq) { 297 ret = devm_request_irq(dev, irq, sama5d4_wdt_irq_handler, 298 IRQF_SHARED | IRQF_IRQPOLL | 299 IRQF_NO_SUSPEND, pdev->name, pdev); 300 if (ret) { 301 dev_err(dev, "cannot register interrupt handler\n"); 302 return ret; 303 } 304 } 305 306 watchdog_init_timeout(wdd, wdt_timeout, dev); 307 308 ret = sama5d4_wdt_init(wdt); 309 if (ret) 310 return ret; 311 312 watchdog_set_nowayout(wdd, nowayout); 313 314 watchdog_stop_on_unregister(wdd); 315 ret = devm_watchdog_register_device(dev, wdd); 316 if (ret) 317 return ret; 318 319 platform_set_drvdata(pdev, wdt); 320 321 dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n", 322 wdd->timeout, nowayout); 323 324 return 0; 325 } 326 327 static const struct of_device_id sama5d4_wdt_of_match[] = { 328 { 329 .compatible = "atmel,sama5d4-wdt", 330 }, 331 { 332 .compatible = "microchip,sam9x60-wdt", 333 }, 334 { 335 .compatible = "microchip,sama7g5-wdt", 336 }, 337 338 { } 339 }; 340 MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match); 341 342 static int sama5d4_wdt_suspend_late(struct device *dev) 343 { 344 struct sama5d4_wdt *wdt = dev_get_drvdata(dev); 345 346 if (watchdog_active(&wdt->wdd)) 347 sama5d4_wdt_stop(&wdt->wdd); 348 349 return 0; 350 } 351 352 static int sama5d4_wdt_resume_early(struct device *dev) 353 { 354 struct sama5d4_wdt *wdt = dev_get_drvdata(dev); 355 356 /* 357 * FIXME: writing MR also pings the watchdog which may not be desired. 358 * This should only be done when the registers are lost on suspend but 359 * there is no way to get this information right now. 360 */ 361 sama5d4_wdt_init(wdt); 362 363 if (watchdog_active(&wdt->wdd)) 364 sama5d4_wdt_start(&wdt->wdd); 365 366 return 0; 367 } 368 369 static const struct dev_pm_ops sama5d4_wdt_pm_ops = { 370 LATE_SYSTEM_SLEEP_PM_OPS(sama5d4_wdt_suspend_late, 371 sama5d4_wdt_resume_early) 372 }; 373 374 static struct platform_driver sama5d4_wdt_driver = { 375 .probe = sama5d4_wdt_probe, 376 .driver = { 377 .name = "sama5d4_wdt", 378 .pm = pm_sleep_ptr(&sama5d4_wdt_pm_ops), 379 .of_match_table = sama5d4_wdt_of_match, 380 } 381 }; 382 module_platform_driver(sama5d4_wdt_driver); 383 384 MODULE_AUTHOR("Atmel Corporation"); 385 MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver"); 386 MODULE_LICENSE("GPL v2"); 387