1 /* 2 * Watchdog driver for Alphascale ASM9260. 3 * 4 * Copyright (c) 2014 Oleksij Rempel <linux@rempel-privat.de> 5 * 6 * Licensed under GPLv2 or later. 7 */ 8 9 #include <linux/bitops.h> 10 #include <linux/clk.h> 11 #include <linux/delay.h> 12 #include <linux/interrupt.h> 13 #include <linux/io.h> 14 #include <linux/module.h> 15 #include <linux/of.h> 16 #include <linux/platform_device.h> 17 #include <linux/reboot.h> 18 #include <linux/reset.h> 19 #include <linux/watchdog.h> 20 21 #define CLOCK_FREQ 1000000 22 23 /* Watchdog Mode register */ 24 #define HW_WDMOD 0x00 25 /* Wake interrupt. Set by HW, can't be cleared. */ 26 #define BM_MOD_WDINT BIT(3) 27 /* This bit set if timeout reached. Cleared by SW. */ 28 #define BM_MOD_WDTOF BIT(2) 29 /* HW Reset on timeout */ 30 #define BM_MOD_WDRESET BIT(1) 31 /* WD enable */ 32 #define BM_MOD_WDEN BIT(0) 33 34 /* 35 * Watchdog Timer Constant register 36 * Minimal value is 0xff, the meaning of this value 37 * depends on used clock: T = WDCLK * (0xff + 1) * 4 38 */ 39 #define HW_WDTC 0x04 40 #define BM_WDTC_MAX(freq) (0x7fffffff / (freq)) 41 42 /* Watchdog Feed register */ 43 #define HW_WDFEED 0x08 44 45 /* Watchdog Timer Value register */ 46 #define HW_WDTV 0x0c 47 48 #define ASM9260_WDT_DEFAULT_TIMEOUT 30 49 50 enum asm9260_wdt_mode { 51 HW_RESET, 52 SW_RESET, 53 DEBUG, 54 }; 55 56 struct asm9260_wdt_priv { 57 struct device *dev; 58 struct watchdog_device wdd; 59 struct clk *clk; 60 struct clk *clk_ahb; 61 struct reset_control *rst; 62 struct notifier_block restart_handler; 63 64 void __iomem *iobase; 65 int irq; 66 unsigned long wdt_freq; 67 enum asm9260_wdt_mode mode; 68 }; 69 70 static int asm9260_wdt_feed(struct watchdog_device *wdd) 71 { 72 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd); 73 74 iowrite32(0xaa, priv->iobase + HW_WDFEED); 75 iowrite32(0x55, priv->iobase + HW_WDFEED); 76 77 return 0; 78 } 79 80 static unsigned int asm9260_wdt_gettimeleft(struct watchdog_device *wdd) 81 { 82 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd); 83 u32 counter; 84 85 counter = ioread32(priv->iobase + HW_WDTV); 86 87 return DIV_ROUND_CLOSEST(counter, priv->wdt_freq); 88 } 89 90 static int asm9260_wdt_updatetimeout(struct watchdog_device *wdd) 91 { 92 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd); 93 u32 counter; 94 95 counter = wdd->timeout * priv->wdt_freq; 96 97 iowrite32(counter, priv->iobase + HW_WDTC); 98 99 return 0; 100 } 101 102 static int asm9260_wdt_enable(struct watchdog_device *wdd) 103 { 104 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd); 105 u32 mode = 0; 106 107 if (priv->mode == HW_RESET) 108 mode = BM_MOD_WDRESET; 109 110 iowrite32(BM_MOD_WDEN | mode, priv->iobase + HW_WDMOD); 111 112 asm9260_wdt_updatetimeout(wdd); 113 114 asm9260_wdt_feed(wdd); 115 116 return 0; 117 } 118 119 static int asm9260_wdt_disable(struct watchdog_device *wdd) 120 { 121 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd); 122 123 /* The only way to disable WD is to reset it. */ 124 reset_control_assert(priv->rst); 125 reset_control_deassert(priv->rst); 126 127 return 0; 128 } 129 130 static int asm9260_wdt_settimeout(struct watchdog_device *wdd, unsigned int to) 131 { 132 wdd->timeout = to; 133 asm9260_wdt_updatetimeout(wdd); 134 135 return 0; 136 } 137 138 static void asm9260_wdt_sys_reset(struct asm9260_wdt_priv *priv) 139 { 140 /* init WD if it was not started */ 141 142 iowrite32(BM_MOD_WDEN | BM_MOD_WDRESET, priv->iobase + HW_WDMOD); 143 144 iowrite32(0xff, priv->iobase + HW_WDTC); 145 /* first pass correct sequence */ 146 asm9260_wdt_feed(&priv->wdd); 147 /* 148 * Then write wrong pattern to the feed to trigger reset 149 * ASAP. 150 */ 151 iowrite32(0xff, priv->iobase + HW_WDFEED); 152 153 mdelay(1000); 154 } 155 156 static irqreturn_t asm9260_wdt_irq(int irq, void *devid) 157 { 158 struct asm9260_wdt_priv *priv = devid; 159 u32 stat; 160 161 stat = ioread32(priv->iobase + HW_WDMOD); 162 if (!(stat & BM_MOD_WDINT)) 163 return IRQ_NONE; 164 165 if (priv->mode == DEBUG) { 166 dev_info(priv->dev, "Watchdog Timeout. Do nothing.\n"); 167 } else { 168 dev_info(priv->dev, "Watchdog Timeout. Doing SW Reset.\n"); 169 asm9260_wdt_sys_reset(priv); 170 } 171 172 return IRQ_HANDLED; 173 } 174 175 static int asm9260_restart_handler(struct notifier_block *this, 176 unsigned long mode, void *cmd) 177 { 178 struct asm9260_wdt_priv *priv = 179 container_of(this, struct asm9260_wdt_priv, restart_handler); 180 181 asm9260_wdt_sys_reset(priv); 182 183 return NOTIFY_DONE; 184 } 185 186 static const struct watchdog_info asm9260_wdt_ident = { 187 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING 188 | WDIOF_MAGICCLOSE, 189 .identity = "Alphascale asm9260 Watchdog", 190 }; 191 192 static struct watchdog_ops asm9260_wdt_ops = { 193 .owner = THIS_MODULE, 194 .start = asm9260_wdt_enable, 195 .stop = asm9260_wdt_disable, 196 .get_timeleft = asm9260_wdt_gettimeleft, 197 .ping = asm9260_wdt_feed, 198 .set_timeout = asm9260_wdt_settimeout, 199 }; 200 201 static int asm9260_wdt_get_dt_clks(struct asm9260_wdt_priv *priv) 202 { 203 int err; 204 unsigned long clk; 205 206 priv->clk = devm_clk_get(priv->dev, "mod"); 207 if (IS_ERR(priv->clk)) { 208 dev_err(priv->dev, "Failed to get \"mod\" clk\n"); 209 return PTR_ERR(priv->clk); 210 } 211 212 /* configure AHB clock */ 213 priv->clk_ahb = devm_clk_get(priv->dev, "ahb"); 214 if (IS_ERR(priv->clk_ahb)) { 215 dev_err(priv->dev, "Failed to get \"ahb\" clk\n"); 216 return PTR_ERR(priv->clk_ahb); 217 } 218 219 err = clk_prepare_enable(priv->clk_ahb); 220 if (err) { 221 dev_err(priv->dev, "Failed to enable ahb_clk!\n"); 222 return err; 223 } 224 225 err = clk_set_rate(priv->clk, CLOCK_FREQ); 226 if (err) { 227 clk_disable_unprepare(priv->clk_ahb); 228 dev_err(priv->dev, "Failed to set rate!\n"); 229 return err; 230 } 231 232 err = clk_prepare_enable(priv->clk); 233 if (err) { 234 clk_disable_unprepare(priv->clk_ahb); 235 dev_err(priv->dev, "Failed to enable clk!\n"); 236 return err; 237 } 238 239 /* wdt has internal divider */ 240 clk = clk_get_rate(priv->clk); 241 if (!clk) { 242 clk_disable_unprepare(priv->clk); 243 clk_disable_unprepare(priv->clk_ahb); 244 dev_err(priv->dev, "Failed, clk is 0!\n"); 245 return -EINVAL; 246 } 247 248 priv->wdt_freq = clk / 2; 249 250 return 0; 251 } 252 253 static void asm9260_wdt_get_dt_mode(struct asm9260_wdt_priv *priv) 254 { 255 const char *tmp; 256 int ret; 257 258 /* default mode */ 259 priv->mode = HW_RESET; 260 261 ret = of_property_read_string(priv->dev->of_node, 262 "alphascale,mode", &tmp); 263 if (ret < 0) 264 return; 265 266 if (!strcmp(tmp, "hw")) 267 priv->mode = HW_RESET; 268 else if (!strcmp(tmp, "sw")) 269 priv->mode = SW_RESET; 270 else if (!strcmp(tmp, "debug")) 271 priv->mode = DEBUG; 272 else 273 dev_warn(priv->dev, "unknown reset-type: %s. Using default \"hw\" mode.", 274 tmp); 275 } 276 277 static int asm9260_wdt_probe(struct platform_device *pdev) 278 { 279 struct asm9260_wdt_priv *priv; 280 struct watchdog_device *wdd; 281 struct resource *res; 282 int ret; 283 const char * const mode_name[] = { "hw", "sw", "debug", }; 284 285 priv = devm_kzalloc(&pdev->dev, sizeof(struct asm9260_wdt_priv), 286 GFP_KERNEL); 287 if (!priv) 288 return -ENOMEM; 289 290 priv->dev = &pdev->dev; 291 292 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 293 priv->iobase = devm_ioremap_resource(&pdev->dev, res); 294 if (IS_ERR(priv->iobase)) 295 return PTR_ERR(priv->iobase); 296 297 ret = asm9260_wdt_get_dt_clks(priv); 298 if (ret) 299 return ret; 300 301 priv->rst = devm_reset_control_get(&pdev->dev, "wdt_rst"); 302 if (IS_ERR(priv->rst)) 303 return PTR_ERR(priv->rst); 304 305 wdd = &priv->wdd; 306 wdd->info = &asm9260_wdt_ident; 307 wdd->ops = &asm9260_wdt_ops; 308 wdd->min_timeout = 1; 309 wdd->max_timeout = BM_WDTC_MAX(priv->wdt_freq); 310 wdd->parent = &pdev->dev; 311 312 watchdog_set_drvdata(wdd, priv); 313 314 /* 315 * If 'timeout-sec' unspecified in devicetree, assume a 30 second 316 * default, unless the max timeout is less than 30 seconds, then use 317 * the max instead. 318 */ 319 wdd->timeout = ASM9260_WDT_DEFAULT_TIMEOUT; 320 watchdog_init_timeout(wdd, 0, &pdev->dev); 321 322 asm9260_wdt_get_dt_mode(priv); 323 324 if (priv->mode != HW_RESET) 325 priv->irq = platform_get_irq(pdev, 0); 326 327 if (priv->irq > 0) { 328 /* 329 * Not all supported platforms specify an interrupt for the 330 * watchdog, so let's make it optional. 331 */ 332 ret = devm_request_irq(&pdev->dev, priv->irq, 333 asm9260_wdt_irq, 0, pdev->name, priv); 334 if (ret < 0) 335 dev_warn(&pdev->dev, "failed to request IRQ\n"); 336 } 337 338 ret = watchdog_register_device(wdd); 339 if (ret) 340 goto clk_off; 341 342 platform_set_drvdata(pdev, priv); 343 344 priv->restart_handler.notifier_call = asm9260_restart_handler; 345 priv->restart_handler.priority = 128; 346 ret = register_restart_handler(&priv->restart_handler); 347 if (ret) 348 dev_warn(&pdev->dev, "cannot register restart handler\n"); 349 350 dev_info(&pdev->dev, "Watchdog enabled (timeout: %d sec, mode: %s)\n", 351 wdd->timeout, mode_name[priv->mode]); 352 return 0; 353 354 clk_off: 355 clk_disable_unprepare(priv->clk); 356 clk_disable_unprepare(priv->clk_ahb); 357 return ret; 358 } 359 360 static void asm9260_wdt_shutdown(struct platform_device *pdev) 361 { 362 struct asm9260_wdt_priv *priv = platform_get_drvdata(pdev); 363 364 asm9260_wdt_disable(&priv->wdd); 365 } 366 367 static int asm9260_wdt_remove(struct platform_device *pdev) 368 { 369 struct asm9260_wdt_priv *priv = platform_get_drvdata(pdev); 370 371 asm9260_wdt_disable(&priv->wdd); 372 373 unregister_restart_handler(&priv->restart_handler); 374 375 watchdog_unregister_device(&priv->wdd); 376 377 clk_disable_unprepare(priv->clk); 378 clk_disable_unprepare(priv->clk_ahb); 379 380 return 0; 381 } 382 383 static const struct of_device_id asm9260_wdt_of_match[] = { 384 { .compatible = "alphascale,asm9260-wdt"}, 385 {}, 386 }; 387 MODULE_DEVICE_TABLE(of, asm9260_wdt_of_match); 388 389 static struct platform_driver asm9260_wdt_driver = { 390 .driver = { 391 .name = "asm9260-wdt", 392 .of_match_table = asm9260_wdt_of_match, 393 }, 394 .probe = asm9260_wdt_probe, 395 .remove = asm9260_wdt_remove, 396 .shutdown = asm9260_wdt_shutdown, 397 }; 398 module_platform_driver(asm9260_wdt_driver); 399 400 MODULE_DESCRIPTION("asm9260 WatchDog Timer Driver"); 401 MODULE_AUTHOR("Oleksij Rempel <linux@rempel-privat.de>"); 402 MODULE_LICENSE("GPL"); 403