drivers/watchdog/dw_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright 2010-2011 Picochip Ltd., Jamie Iles
   4  * https://www.picochip.com
   5  *
   6  * This file implements a driver for the Synopsys DesignWare watchdog device
   7  * in the many subsystems. The watchdog has 16 different timeout periods
   8  * and these are a function of the input clock frequency.
   9  *
  10  * The DesignWare watchdog cannot be stopped once it has been started so we
  11  * do not implement a stop function. The watchdog core will continue to send
  12  * heartbeat requests after the watchdog device has been closed.
  13  */
  14
  15 #include <linux/bitops.h>
  16 #include <linux/clk.h>
  17 #include <linux/debugfs.h>
  18 #include <linux/delay.h>
  19 #include <linux/err.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/io.h>
  22 #include <linux/kernel.h>
  23 #include <linux/limits.h>
  24 #include <linux/module.h>
  25 #include <linux/moduleparam.h>
  26 #include <linux/of.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/pm.h>
  29 #include <linux/reset.h>
  30 #include <linux/watchdog.h>
  31
  32 #define WDOG_CONTROL_REG_OFFSET             0x00
  33 #define WDOG_CONTROL_REG_WDT_EN_MASK        0x01
  34 #define WDOG_CONTROL_REG_RESP_MODE_MASK     0x02
  35 #define WDOG_TIMEOUT_RANGE_REG_OFFSET       0x04
  36 #define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT    4
  37 #define WDOG_CURRENT_COUNT_REG_OFFSET       0x08
  38 #define WDOG_COUNTER_RESTART_REG_OFFSET     0x0c
  39 #define WDOG_COUNTER_RESTART_KICK_VALUE     0x76
  40 #define WDOG_INTERRUPT_STATUS_REG_OFFSET    0x10
  41 #define WDOG_INTERRUPT_CLEAR_REG_OFFSET     0x14
  42 #define WDOG_COMP_PARAMS_5_REG_OFFSET       0xe4
  43 #define WDOG_COMP_PARAMS_4_REG_OFFSET       0xe8
  44 #define WDOG_COMP_PARAMS_3_REG_OFFSET       0xec
  45 #define WDOG_COMP_PARAMS_2_REG_OFFSET       0xf0
  46 #define WDOG_COMP_PARAMS_1_REG_OFFSET       0xf4
  47 #define WDOG_COMP_PARAMS_1_USE_FIX_TOP      BIT(6)
  48 #define WDOG_COMP_VERSION_REG_OFFSET        0xf8
  49 #define WDOG_COMP_TYPE_REG_OFFSET           0xfc
  50
  51 /* There are sixteen TOPs (timeout periods) that can be set in the watchdog. */
  52 #define DW_WDT_NUM_TOPS         16
  53 #define DW_WDT_FIX_TOP(_idx)    (1U << (16 + _idx))
  54
  55 #define DW_WDT_DEFAULT_SECONDS  30
  56
  57 static const u32 dw_wdt_fix_tops[DW_WDT_NUM_TOPS] = {
  58         DW_WDT_FIX_TOP(0), DW_WDT_FIX_TOP(1), DW_WDT_FIX_TOP(2),
  59         DW_WDT_FIX_TOP(3), DW_WDT_FIX_TOP(4), DW_WDT_FIX_TOP(5),
  60         DW_WDT_FIX_TOP(6), DW_WDT_FIX_TOP(7), DW_WDT_FIX_TOP(8),
  61         DW_WDT_FIX_TOP(9), DW_WDT_FIX_TOP(10), DW_WDT_FIX_TOP(11),
  62         DW_WDT_FIX_TOP(12), DW_WDT_FIX_TOP(13), DW_WDT_FIX_TOP(14),
  63         DW_WDT_FIX_TOP(15)
  64 };
  65
  66 static bool nowayout = WATCHDOG_NOWAYOUT;
  67 module_param(nowayout, bool, 0);
  68 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  69                  "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  70
  71 enum dw_wdt_rmod {
  72         DW_WDT_RMOD_RESET = 1,
  73         DW_WDT_RMOD_IRQ = 2
  74 };
  75
  76 struct dw_wdt_timeout {
  77         u32 top_val;
  78         unsigned int sec;
  79         unsigned int msec;
  80 };
  81
  82 struct dw_wdt {
  83         void __iomem            *regs;
  84         struct clk              *clk;
  85         struct clk              *pclk;
  86         unsigned long           rate;
  87         enum dw_wdt_rmod        rmod;
  88         struct dw_wdt_timeout   timeouts[DW_WDT_NUM_TOPS];
  89         struct watchdog_device  wdd;
  90         struct reset_control    *rst;
  91         /* Save/restore */
  92         u32                     control;
  93         u32                     timeout;
  94
  95 #ifdef CONFIG_DEBUG_FS
  96         struct dentry           *dbgfs_dir;
  97 #endif
  98 };
  99
 100 #define to_dw_wdt(wdd)  container_of(wdd, struct dw_wdt, wdd)
 101
 102 static inline int dw_wdt_is_enabled(struct dw_wdt *dw_wdt)
 103 {
 104         return readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET) &
 105                 WDOG_CONTROL_REG_WDT_EN_MASK;
 106 }
 107
 108 static void dw_wdt_update_mode(struct dw_wdt *dw_wdt, enum dw_wdt_rmod rmod)
 109 {
 110         u32 val;
 111
 112         val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 113         if (rmod == DW_WDT_RMOD_IRQ)
 114                 val |= WDOG_CONTROL_REG_RESP_MODE_MASK;
 115         else
 116                 val &= ~WDOG_CONTROL_REG_RESP_MODE_MASK;
 117         writel(val, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 118
 119         dw_wdt->rmod = rmod;
 120 }
 121
 122 static unsigned int dw_wdt_find_best_top(struct dw_wdt *dw_wdt,
 123                                          unsigned int timeout, u32 *top_val)
 124 {
 125         int idx;
 126
 127         /*
 128          * Find a TOP with timeout greater or equal to the requested number.
 129          * Note we'll select a TOP with maximum timeout if the requested
 130          * timeout couldn't be reached.
 131          */
 132         for (idx = 0; idx < DW_WDT_NUM_TOPS; ++idx) {
 133                 if (dw_wdt->timeouts[idx].sec >= timeout)
 134                         break;
 135         }
 136
 137         if (idx == DW_WDT_NUM_TOPS)
 138                 --idx;
 139
 140         *top_val = dw_wdt->timeouts[idx].top_val;
 141
 142         return dw_wdt->timeouts[idx].sec;
 143 }
 144
 145 static unsigned int dw_wdt_get_min_timeout(struct dw_wdt *dw_wdt)
 146 {
 147         int idx;
 148
 149         /*
 150          * We'll find a timeout greater or equal to one second anyway because
 151          * the driver probe would have failed if there was none.
 152          */
 153         for (idx = 0; idx < DW_WDT_NUM_TOPS; ++idx) {
 154                 if (dw_wdt->timeouts[idx].sec)
 155                         break;
 156         }
 157
 158         return dw_wdt->timeouts[idx].sec;
 159 }
 160
 161 static unsigned int dw_wdt_get_max_timeout_ms(struct dw_wdt *dw_wdt)
 162 {
 163         struct dw_wdt_timeout *timeout = &dw_wdt->timeouts[DW_WDT_NUM_TOPS - 1];
 164         u64 msec;
 165
 166         msec = (u64)timeout->sec * MSEC_PER_SEC + timeout->msec;
 167
 168         return msec < UINT_MAX ? msec : UINT_MAX;
 169 }
 170
 171 static unsigned int dw_wdt_get_timeout(struct dw_wdt *dw_wdt)
 172 {
 173         int top_val = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
 174         int idx;
 175
 176         for (idx = 0; idx < DW_WDT_NUM_TOPS; ++idx) {
 177                 if (dw_wdt->timeouts[idx].top_val == top_val)
 178                         break;
 179         }
 180
 181         /*
 182          * In IRQ mode due to the two stages counter, the actual timeout is
 183          * twice greater than the TOP setting.
 184          */
 185         return dw_wdt->timeouts[idx].sec * dw_wdt->rmod;
 186 }
 187
 188 static int dw_wdt_ping(struct watchdog_device *wdd)
 189 {
 190         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 191
 192         writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt->regs +
 193                WDOG_COUNTER_RESTART_REG_OFFSET);
 194
 195         return 0;
 196 }
 197
 198 static int dw_wdt_set_timeout(struct watchdog_device *wdd, unsigned int top_s)
 199 {
 200         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 201         unsigned int timeout;
 202         u32 top_val;
 203
 204         /*
 205          * Note IRQ mode being enabled means having a non-zero pre-timeout
 206          * setup. In this case we try to find a TOP as close to the half of the
 207          * requested timeout as possible since DW Watchdog IRQ mode is designed
 208          * in two stages way - first timeout rises the pre-timeout interrupt,
 209          * second timeout performs the system reset. So basically the effective
 210          * watchdog-caused reset happens after two watchdog TOPs elapsed.
 211          */
 212         timeout = dw_wdt_find_best_top(dw_wdt, DIV_ROUND_UP(top_s, dw_wdt->rmod),
 213                                        &top_val);
 214         if (dw_wdt->rmod == DW_WDT_RMOD_IRQ)
 215                 wdd->pretimeout = timeout;
 216         else
 217                 wdd->pretimeout = 0;
 218
 219         /*
 220          * Set the new value in the watchdog.  Some versions of dw_wdt
 221          * have have TOPINIT in the TIMEOUT_RANGE register (as per
 222          * CP_WDT_DUAL_TOP in WDT_COMP_PARAMS_1).  On those we
 223          * effectively get a pat of the watchdog right here.
 224          */
 225         writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
 226                dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 227
 228         /* Kick new TOP value into the watchdog counter if activated. */
 229         if (watchdog_active(wdd))
 230                 dw_wdt_ping(wdd);
 231
 232         /*
 233          * In case users set bigger timeout value than HW can support,
 234          * kernel(watchdog_dev.c) helps to feed watchdog before
 235          * wdd->max_hw_heartbeat_ms
 236          */
 237         if (top_s * 1000 <= wdd->max_hw_heartbeat_ms)
 238                 wdd->timeout = timeout * dw_wdt->rmod;
 239         else
 240                 wdd->timeout = top_s;
 241
 242         return 0;
 243 }
 244
 245 static int dw_wdt_set_pretimeout(struct watchdog_device *wdd, unsigned int req)
 246 {
 247         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 248
 249         /*
 250          * We ignore actual value of the timeout passed from user-space
 251          * using it as a flag whether the pretimeout functionality is intended
 252          * to be activated.
 253          */
 254         dw_wdt_update_mode(dw_wdt, req ? DW_WDT_RMOD_IRQ : DW_WDT_RMOD_RESET);
 255         dw_wdt_set_timeout(wdd, wdd->timeout);
 256
 257         return 0;
 258 }
 259
 260 static void dw_wdt_arm_system_reset(struct dw_wdt *dw_wdt)
 261 {
 262         u32 val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 263
 264         /* Disable/enable interrupt mode depending on the RMOD flag. */
 265         if (dw_wdt->rmod == DW_WDT_RMOD_IRQ)
 266                 val |= WDOG_CONTROL_REG_RESP_MODE_MASK;
 267         else
 268                 val &= ~WDOG_CONTROL_REG_RESP_MODE_MASK;
 269         /* Enable watchdog. */
 270         val |= WDOG_CONTROL_REG_WDT_EN_MASK;
 271         writel(val, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 272 }
 273
 274 static int dw_wdt_start(struct watchdog_device *wdd)
 275 {
 276         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 277
 278         dw_wdt_set_timeout(wdd, wdd->timeout);
 279         dw_wdt_ping(&dw_wdt->wdd);
 280         dw_wdt_arm_system_reset(dw_wdt);
 281
 282         return 0;
 283 }
 284
 285 static int dw_wdt_stop(struct watchdog_device *wdd)
 286 {
 287         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 288
 289         if (!dw_wdt->rst) {
 290                 set_bit(WDOG_HW_RUNNING, &wdd->status);
 291                 return 0;
 292         }
 293
 294         reset_control_assert(dw_wdt->rst);
 295         reset_control_deassert(dw_wdt->rst);
 296
 297         return 0;
 298 }
 299
 300 static int dw_wdt_restart(struct watchdog_device *wdd,
 301                           unsigned long action, void *data)
 302 {
 303         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 304
 305         writel(0, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 306         dw_wdt_update_mode(dw_wdt, DW_WDT_RMOD_RESET);
 307         if (dw_wdt_is_enabled(dw_wdt))
 308                 writel(WDOG_COUNTER_RESTART_KICK_VALUE,
 309                        dw_wdt->regs + WDOG_COUNTER_RESTART_REG_OFFSET);
 310         else
 311                 dw_wdt_arm_system_reset(dw_wdt);
 312
 313         /* wait for reset to assert... */
 314         mdelay(500);
 315
 316         return 0;
 317 }
 318
 319 static unsigned int dw_wdt_get_timeleft(struct watchdog_device *wdd)
 320 {
 321         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 322         unsigned int sec;
 323         u32 val;
 324
 325         val = readl(dw_wdt->regs + WDOG_CURRENT_COUNT_REG_OFFSET);
 326         sec = val / dw_wdt->rate;
 327
 328         if (dw_wdt->rmod == DW_WDT_RMOD_IRQ) {
 329                 val = readl(dw_wdt->regs + WDOG_INTERRUPT_STATUS_REG_OFFSET);
 330                 if (!val)
 331                         sec += wdd->pretimeout;
 332         }
 333
 334         return sec;
 335 }
 336
 337 static const struct watchdog_info dw_wdt_ident = {
 338         .options        = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 339                           WDIOF_MAGICCLOSE,
 340         .identity       = "Synopsys DesignWare Watchdog",
 341 };
 342
 343 static const struct watchdog_info dw_wdt_pt_ident = {
 344         .options        = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 345                           WDIOF_PRETIMEOUT | WDIOF_MAGICCLOSE,
 346         .identity       = "Synopsys DesignWare Watchdog",
 347 };
 348
 349 static const struct watchdog_ops dw_wdt_ops = {
 350         .owner          = THIS_MODULE,
 351         .start          = dw_wdt_start,
 352         .stop           = dw_wdt_stop,
 353         .ping           = dw_wdt_ping,
 354         .set_timeout    = dw_wdt_set_timeout,
 355         .set_pretimeout = dw_wdt_set_pretimeout,
 356         .get_timeleft   = dw_wdt_get_timeleft,
 357         .restart        = dw_wdt_restart,
 358 };
 359
 360 static irqreturn_t dw_wdt_irq(int irq, void *devid)
 361 {
 362         struct dw_wdt *dw_wdt = devid;
 363         u32 val;
 364
 365         /*
 366          * We don't clear the IRQ status. It's supposed to be done by the
 367          * following ping operations.
 368          */
 369         val = readl(dw_wdt->regs + WDOG_INTERRUPT_STATUS_REG_OFFSET);
 370         if (!val)
 371                 return IRQ_NONE;
 372
 373         watchdog_notify_pretimeout(&dw_wdt->wdd);
 374
 375         return IRQ_HANDLED;
 376 }
 377
 378 #ifdef CONFIG_PM_SLEEP
 379 static int dw_wdt_suspend(struct device *dev)
 380 {
 381         struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
 382
 383         dw_wdt->control = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 384         dw_wdt->timeout = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 385
 386         clk_disable_unprepare(dw_wdt->pclk);
 387         clk_disable_unprepare(dw_wdt->clk);
 388
 389         return 0;
 390 }
 391
 392 static int dw_wdt_resume(struct device *dev)
 393 {
 394         struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
 395         int err = clk_prepare_enable(dw_wdt->clk);
 396
 397         if (err)
 398                 return err;
 399
 400         err = clk_prepare_enable(dw_wdt->pclk);
 401         if (err) {
 402                 clk_disable_unprepare(dw_wdt->clk);
 403                 return err;
 404         }
 405
 406         writel(dw_wdt->timeout, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 407         writel(dw_wdt->control, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 408
 409         dw_wdt_ping(&dw_wdt->wdd);
 410
 411         return 0;
 412 }
 413 #endif /* CONFIG_PM_SLEEP */
 414
 415 static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
 416
 417 /*
 418  * In case if DW WDT IP core is synthesized with fixed TOP feature disabled the
 419  * TOPs array can be arbitrary ordered with nearly any sixteen uint numbers
 420  * depending on the system engineer imagination. The next method handles the
 421  * passed TOPs array to pre-calculate the effective timeouts and to sort the
 422  * TOP items out in the ascending order with respect to the timeouts.
 423  */
 424
 425 static void dw_wdt_handle_tops(struct dw_wdt *dw_wdt, const u32 *tops)
 426 {
 427         struct dw_wdt_timeout tout, *dst;
 428         int val, tidx;
 429         u64 msec;
 430
 431         /*
 432          * We walk over the passed TOPs array and calculate corresponding
 433          * timeouts in seconds and milliseconds. The milliseconds granularity
 434          * is needed to distinguish the TOPs with very close timeouts and to
 435          * set the watchdog max heartbeat setting further.
 436          */
 437         for (val = 0; val < DW_WDT_NUM_TOPS; ++val) {
 438                 tout.top_val = val;
 439                 tout.sec = tops[val] / dw_wdt->rate;
 440                 msec = (u64)tops[val] * MSEC_PER_SEC;
 441                 do_div(msec, dw_wdt->rate);
 442                 tout.msec = msec - ((u64)tout.sec * MSEC_PER_SEC);
 443
 444                 /*
 445                  * Find a suitable place for the current TOP in the timeouts
 446                  * array so that the list is remained in the ascending order.
 447                  */
 448                 for (tidx = 0; tidx < val; ++tidx) {
 449                         dst = &dw_wdt->timeouts[tidx];
 450                         if (tout.sec > dst->sec || (tout.sec == dst->sec &&
 451                             tout.msec >= dst->msec))
 452                                 continue;
 453                         else
 454                                 swap(*dst, tout);
 455                 }
 456
 457                 dw_wdt->timeouts[val] = tout;
 458         }
 459 }
 460
 461 static int dw_wdt_init_timeouts(struct dw_wdt *dw_wdt, struct device *dev)
 462 {
 463         u32 data, of_tops[DW_WDT_NUM_TOPS];
 464         const u32 *tops;
 465         int ret;
 466
 467         /*
 468          * Retrieve custom or fixed counter values depending on the
 469          * WDT_USE_FIX_TOP flag found in the component specific parameters
 470          * #1 register.
 471          */
 472         data = readl(dw_wdt->regs + WDOG_COMP_PARAMS_1_REG_OFFSET);
 473         if (data & WDOG_COMP_PARAMS_1_USE_FIX_TOP) {
 474                 tops = dw_wdt_fix_tops;
 475         } else {
 476                 ret = of_property_read_variable_u32_array(dev_of_node(dev),
 477                         "snps,watchdog-tops", of_tops, DW_WDT_NUM_TOPS,
 478                         DW_WDT_NUM_TOPS);
 479                 if (ret < 0) {
 480                         dev_warn(dev, "No valid TOPs array specified\n");
 481                         tops = dw_wdt_fix_tops;
 482                 } else {
 483                         tops = of_tops;
 484                 }
 485         }
 486
 487         /* Convert the specified TOPs into an array of watchdog timeouts. */
 488         dw_wdt_handle_tops(dw_wdt, tops);
 489         if (!dw_wdt->timeouts[DW_WDT_NUM_TOPS - 1].sec) {
 490                 dev_err(dev, "No any valid TOP detected\n");
 491                 return -EINVAL;
 492         }
 493
 494         return 0;
 495 }
 496
 497 #ifdef CONFIG_DEBUG_FS
 498
 499 #define DW_WDT_DBGFS_REG(_name, _off) \
 500 {                                     \
 501         .name = _name,                \
 502         .offset = _off                \
 503 }
 504
 505 static const struct debugfs_reg32 dw_wdt_dbgfs_regs[] = {
 506         DW_WDT_DBGFS_REG("cr", WDOG_CONTROL_REG_OFFSET),
 507         DW_WDT_DBGFS_REG("torr", WDOG_TIMEOUT_RANGE_REG_OFFSET),
 508         DW_WDT_DBGFS_REG("ccvr", WDOG_CURRENT_COUNT_REG_OFFSET),
 509         DW_WDT_DBGFS_REG("crr", WDOG_COUNTER_RESTART_REG_OFFSET),
 510         DW_WDT_DBGFS_REG("stat", WDOG_INTERRUPT_STATUS_REG_OFFSET),
 511         DW_WDT_DBGFS_REG("param5", WDOG_COMP_PARAMS_5_REG_OFFSET),
 512         DW_WDT_DBGFS_REG("param4", WDOG_COMP_PARAMS_4_REG_OFFSET),
 513         DW_WDT_DBGFS_REG("param3", WDOG_COMP_PARAMS_3_REG_OFFSET),
 514         DW_WDT_DBGFS_REG("param2", WDOG_COMP_PARAMS_2_REG_OFFSET),
 515         DW_WDT_DBGFS_REG("param1", WDOG_COMP_PARAMS_1_REG_OFFSET),
 516         DW_WDT_DBGFS_REG("version", WDOG_COMP_VERSION_REG_OFFSET),
 517         DW_WDT_DBGFS_REG("type", WDOG_COMP_TYPE_REG_OFFSET)
 518 };
 519
 520 static void dw_wdt_dbgfs_init(struct dw_wdt *dw_wdt)
 521 {
 522         struct device *dev = dw_wdt->wdd.parent;
 523         struct debugfs_regset32 *regset;
 524
 525         regset = devm_kzalloc(dev, sizeof(*regset), GFP_KERNEL);
 526         if (!regset)
 527                 return;
 528
 529         regset->regs = dw_wdt_dbgfs_regs;
 530         regset->nregs = ARRAY_SIZE(dw_wdt_dbgfs_regs);
 531         regset->base = dw_wdt->regs;
 532
 533         dw_wdt->dbgfs_dir = debugfs_create_dir(dev_name(dev), NULL);
 534
 535         debugfs_create_regset32("registers", 0444, dw_wdt->dbgfs_dir, regset);
 536 }
 537
 538 static void dw_wdt_dbgfs_clear(struct dw_wdt *dw_wdt)
 539 {
 540         debugfs_remove_recursive(dw_wdt->dbgfs_dir);
 541 }
 542
 543 #else /* !CONFIG_DEBUG_FS */
 544
 545 static void dw_wdt_dbgfs_init(struct dw_wdt *dw_wdt) {}
 546 static void dw_wdt_dbgfs_clear(struct dw_wdt *dw_wdt) {}
 547
 548 #endif /* !CONFIG_DEBUG_FS */
 549
 550 static int dw_wdt_drv_probe(struct platform_device *pdev)
 551 {
 552         struct device *dev = &pdev->dev;
 553         struct watchdog_device *wdd;
 554         struct dw_wdt *dw_wdt;
 555         int ret;
 556
 557         dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);
 558         if (!dw_wdt)
 559                 return -ENOMEM;
 560
 561         dw_wdt->regs = devm_platform_ioremap_resource(pdev, 0);
 562         if (IS_ERR(dw_wdt->regs))
 563                 return PTR_ERR(dw_wdt->regs);
 564
 565         /*
 566          * Try to request the watchdog dedicated timer clock source. It must
 567          * be supplied if asynchronous mode is enabled. Otherwise fallback
 568          * to the common timer/bus clocks configuration, in which the very
 569          * first found clock supply both timer and APB signals.
 570          */
 571         dw_wdt->clk = devm_clk_get(dev, "tclk");
 572         if (IS_ERR(dw_wdt->clk)) {
 573                 dw_wdt->clk = devm_clk_get(dev, NULL);
 574                 if (IS_ERR(dw_wdt->clk))
 575                         return PTR_ERR(dw_wdt->clk);
 576         }
 577
 578         ret = clk_prepare_enable(dw_wdt->clk);
 579         if (ret)
 580                 return ret;
 581
 582         dw_wdt->rate = clk_get_rate(dw_wdt->clk);
 583         if (dw_wdt->rate == 0) {
 584                 ret = -EINVAL;
 585                 goto out_disable_clk;
 586         }
 587
 588         /*
 589          * Request APB clock if device is configured with async clocks mode.
 590          * In this case both tclk and pclk clocks are supposed to be specified.
 591          * Alas we can't know for sure whether async mode was really activated,
 592          * so the pclk phandle reference is left optional. If it couldn't be
 593          * found we consider the device configured in synchronous clocks mode.
 594          */
 595         dw_wdt->pclk = devm_clk_get_optional(dev, "pclk");
 596         if (IS_ERR(dw_wdt->pclk)) {
 597                 ret = PTR_ERR(dw_wdt->pclk);
 598                 goto out_disable_clk;
 599         }
 600
 601         ret = clk_prepare_enable(dw_wdt->pclk);
 602         if (ret)
 603                 goto out_disable_clk;
 604
 605         dw_wdt->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
 606         if (IS_ERR(dw_wdt->rst)) {
 607                 ret = PTR_ERR(dw_wdt->rst);
 608                 goto out_disable_pclk;
 609         }
 610
 611         /* Enable normal reset without pre-timeout by default. */
 612         dw_wdt_update_mode(dw_wdt, DW_WDT_RMOD_RESET);
 613
 614         /*
 615          * Pre-timeout IRQ is optional, since some hardware may lack support
 616          * of it. Note we must request rising-edge IRQ, since the lane is left
 617          * pending either until the next watchdog kick event or up to the
 618          * system reset.
 619          */
 620         ret = platform_get_irq_optional(pdev, 0);
 621         if (ret > 0) {
 622                 ret = devm_request_irq(dev, ret, dw_wdt_irq,
 623                                        IRQF_SHARED | IRQF_TRIGGER_RISING,
 624                                        pdev->name, dw_wdt);
 625                 if (ret)
 626                         goto out_disable_pclk;
 627
 628                 dw_wdt->wdd.info = &dw_wdt_pt_ident;
 629         } else {
 630                 if (ret == -EPROBE_DEFER)
 631                         goto out_disable_pclk;
 632
 633                 dw_wdt->wdd.info = &dw_wdt_ident;
 634         }
 635
 636         reset_control_deassert(dw_wdt->rst);
 637
 638         ret = dw_wdt_init_timeouts(dw_wdt, dev);
 639         if (ret)
 640                 goto out_disable_clk;
 641
 642         wdd = &dw_wdt->wdd;
 643         wdd->ops = &dw_wdt_ops;
 644         wdd->min_timeout = dw_wdt_get_min_timeout(dw_wdt);
 645         wdd->max_hw_heartbeat_ms = dw_wdt_get_max_timeout_ms(dw_wdt);
 646         wdd->parent = dev;
 647
 648         watchdog_set_drvdata(wdd, dw_wdt);
 649         watchdog_set_nowayout(wdd, nowayout);
 650         watchdog_init_timeout(wdd, 0, dev);
 651
 652         /*
 653          * If the watchdog is already running, use its already configured
 654          * timeout. Otherwise use the default or the value provided through
 655          * devicetree.
 656          */
 657         if (dw_wdt_is_enabled(dw_wdt)) {
 658                 wdd->timeout = dw_wdt_get_timeout(dw_wdt);
 659                 set_bit(WDOG_HW_RUNNING, &wdd->status);
 660         } else {
 661                 wdd->timeout = DW_WDT_DEFAULT_SECONDS;
 662                 watchdog_init_timeout(wdd, 0, dev);
 663         }
 664
 665         platform_set_drvdata(pdev, dw_wdt);
 666
 667         watchdog_set_restart_priority(wdd, 128);
 668
 669         ret = watchdog_register_device(wdd);
 670         if (ret)
 671                 goto out_disable_pclk;
 672
 673         dw_wdt_dbgfs_init(dw_wdt);
 674
 675         return 0;
 676
 677 out_disable_pclk:
 678         clk_disable_unprepare(dw_wdt->pclk);
 679
 680 out_disable_clk:
 681         clk_disable_unprepare(dw_wdt->clk);
 682         return ret;
 683 }
 684
 685 static int dw_wdt_drv_remove(struct platform_device *pdev)
 686 {
 687         struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);
 688
 689         dw_wdt_dbgfs_clear(dw_wdt);
 690
 691         watchdog_unregister_device(&dw_wdt->wdd);
 692         reset_control_assert(dw_wdt->rst);
 693         clk_disable_unprepare(dw_wdt->pclk);
 694         clk_disable_unprepare(dw_wdt->clk);
 695
 696         return 0;
 697 }
 698
 699 #ifdef CONFIG_OF
 700 static const struct of_device_id dw_wdt_of_match[] = {
 701         { .compatible = "snps,dw-wdt", },
 702         { /* sentinel */ }
 703 };
 704 MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
 705 #endif
 706
 707 static struct platform_driver dw_wdt_driver = {
 708         .probe          = dw_wdt_drv_probe,
 709         .remove         = dw_wdt_drv_remove,
 710         .driver         = {
 711                 .name   = "dw_wdt",
 712                 .of_match_table = of_match_ptr(dw_wdt_of_match),
 713                 .pm     = &dw_wdt_pm_ops,
 714         },
 715 };
 716
 717 module_platform_driver(dw_wdt_driver);
 718
 719 MODULE_AUTHOR("Jamie Iles");
 720 MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
 721 MODULE_LICENSE("GPL");