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 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 static int dw_wdt_suspend(struct device *dev)
 379 {
 380         struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
 381
 382         dw_wdt->control = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 383         dw_wdt->timeout = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 384
 385         clk_disable_unprepare(dw_wdt->pclk);
 386         clk_disable_unprepare(dw_wdt->clk);
 387
 388         return 0;
 389 }
 390
 391 static int dw_wdt_resume(struct device *dev)
 392 {
 393         struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
 394         int err = clk_prepare_enable(dw_wdt->clk);
 395
 396         if (err)
 397                 return err;
 398
 399         err = clk_prepare_enable(dw_wdt->pclk);
 400         if (err) {
 401                 clk_disable_unprepare(dw_wdt->clk);
 402                 return err;
 403         }
 404
 405         writel(dw_wdt->timeout, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
 406         writel(dw_wdt->control, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
 407
 408         dw_wdt_ping(&dw_wdt->wdd);
 409
 410         return 0;
 411 }
 412
 413 static DEFINE_SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
 414
 415 /*
 416  * In case if DW WDT IP core is synthesized with fixed TOP feature disabled the
 417  * TOPs array can be arbitrary ordered with nearly any sixteen uint numbers
 418  * depending on the system engineer imagination. The next method handles the
 419  * passed TOPs array to pre-calculate the effective timeouts and to sort the
 420  * TOP items out in the ascending order with respect to the timeouts.
 421  */
 422
 423 static void dw_wdt_handle_tops(struct dw_wdt *dw_wdt, const u32 *tops)
 424 {
 425         struct dw_wdt_timeout tout, *dst;
 426         int val, tidx;
 427         u64 msec;
 428
 429         /*
 430          * We walk over the passed TOPs array and calculate corresponding
 431          * timeouts in seconds and milliseconds. The milliseconds granularity
 432          * is needed to distinguish the TOPs with very close timeouts and to
 433          * set the watchdog max heartbeat setting further.
 434          */
 435         for (val = 0; val < DW_WDT_NUM_TOPS; ++val) {
 436                 tout.top_val = val;
 437                 tout.sec = tops[val] / dw_wdt->rate;
 438                 msec = (u64)tops[val] * MSEC_PER_SEC;
 439                 do_div(msec, dw_wdt->rate);
 440                 tout.msec = msec - ((u64)tout.sec * MSEC_PER_SEC);
 441
 442                 /*
 443                  * Find a suitable place for the current TOP in the timeouts
 444                  * array so that the list is remained in the ascending order.
 445                  */
 446                 for (tidx = 0; tidx < val; ++tidx) {
 447                         dst = &dw_wdt->timeouts[tidx];
 448                         if (tout.sec > dst->sec || (tout.sec == dst->sec &&
 449                             tout.msec >= dst->msec))
 450                                 continue;
 451                         else
 452                                 swap(*dst, tout);
 453                 }
 454
 455                 dw_wdt->timeouts[val] = tout;
 456         }
 457 }
 458
 459 static int dw_wdt_init_timeouts(struct dw_wdt *dw_wdt, struct device *dev)
 460 {
 461         u32 data, of_tops[DW_WDT_NUM_TOPS];
 462         const u32 *tops;
 463         int ret;
 464
 465         /*
 466          * Retrieve custom or fixed counter values depending on the
 467          * WDT_USE_FIX_TOP flag found in the component specific parameters
 468          * #1 register.
 469          */
 470         data = readl(dw_wdt->regs + WDOG_COMP_PARAMS_1_REG_OFFSET);
 471         if (data & WDOG_COMP_PARAMS_1_USE_FIX_TOP) {
 472                 tops = dw_wdt_fix_tops;
 473         } else {
 474                 ret = of_property_read_variable_u32_array(dev_of_node(dev),
 475                         "snps,watchdog-tops", of_tops, DW_WDT_NUM_TOPS,
 476                         DW_WDT_NUM_TOPS);
 477                 if (ret < 0) {
 478                         dev_warn(dev, "No valid TOPs array specified\n");
 479                         tops = dw_wdt_fix_tops;
 480                 } else {
 481                         tops = of_tops;
 482                 }
 483         }
 484
 485         /* Convert the specified TOPs into an array of watchdog timeouts. */
 486         dw_wdt_handle_tops(dw_wdt, tops);
 487         if (!dw_wdt->timeouts[DW_WDT_NUM_TOPS - 1].sec) {
 488                 dev_err(dev, "No any valid TOP detected\n");
 489                 return -EINVAL;
 490         }
 491
 492         return 0;
 493 }
 494
 495 #ifdef CONFIG_DEBUG_FS
 496
 497 #define DW_WDT_DBGFS_REG(_name, _off) \
 498 {                                     \
 499         .name = _name,                \
 500         .offset = _off                \
 501 }
 502
 503 static const struct debugfs_reg32 dw_wdt_dbgfs_regs[] = {
 504         DW_WDT_DBGFS_REG("cr", WDOG_CONTROL_REG_OFFSET),
 505         DW_WDT_DBGFS_REG("torr", WDOG_TIMEOUT_RANGE_REG_OFFSET),
 506         DW_WDT_DBGFS_REG("ccvr", WDOG_CURRENT_COUNT_REG_OFFSET),
 507         DW_WDT_DBGFS_REG("crr", WDOG_COUNTER_RESTART_REG_OFFSET),
 508         DW_WDT_DBGFS_REG("stat", WDOG_INTERRUPT_STATUS_REG_OFFSET),
 509         DW_WDT_DBGFS_REG("param5", WDOG_COMP_PARAMS_5_REG_OFFSET),
 510         DW_WDT_DBGFS_REG("param4", WDOG_COMP_PARAMS_4_REG_OFFSET),
 511         DW_WDT_DBGFS_REG("param3", WDOG_COMP_PARAMS_3_REG_OFFSET),
 512         DW_WDT_DBGFS_REG("param2", WDOG_COMP_PARAMS_2_REG_OFFSET),
 513         DW_WDT_DBGFS_REG("param1", WDOG_COMP_PARAMS_1_REG_OFFSET),
 514         DW_WDT_DBGFS_REG("version", WDOG_COMP_VERSION_REG_OFFSET),
 515         DW_WDT_DBGFS_REG("type", WDOG_COMP_TYPE_REG_OFFSET)
 516 };
 517
 518 static void dw_wdt_dbgfs_init(struct dw_wdt *dw_wdt)
 519 {
 520         struct device *dev = dw_wdt->wdd.parent;
 521         struct debugfs_regset32 *regset;
 522
 523         regset = devm_kzalloc(dev, sizeof(*regset), GFP_KERNEL);
 524         if (!regset)
 525                 return;
 526
 527         regset->regs = dw_wdt_dbgfs_regs;
 528         regset->nregs = ARRAY_SIZE(dw_wdt_dbgfs_regs);
 529         regset->base = dw_wdt->regs;
 530
 531         dw_wdt->dbgfs_dir = debugfs_create_dir(dev_name(dev), NULL);
 532
 533         debugfs_create_regset32("registers", 0444, dw_wdt->dbgfs_dir, regset);
 534 }
 535
 536 static void dw_wdt_dbgfs_clear(struct dw_wdt *dw_wdt)
 537 {
 538         debugfs_remove_recursive(dw_wdt->dbgfs_dir);
 539 }
 540
 541 #else /* !CONFIG_DEBUG_FS */
 542
 543 static void dw_wdt_dbgfs_init(struct dw_wdt *dw_wdt) {}
 544 static void dw_wdt_dbgfs_clear(struct dw_wdt *dw_wdt) {}
 545
 546 #endif /* !CONFIG_DEBUG_FS */
 547
 548 static int dw_wdt_drv_probe(struct platform_device *pdev)
 549 {
 550         struct device *dev = &pdev->dev;
 551         struct watchdog_device *wdd;
 552         struct dw_wdt *dw_wdt;
 553         int ret;
 554
 555         dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);
 556         if (!dw_wdt)
 557                 return -ENOMEM;
 558
 559         dw_wdt->regs = devm_platform_ioremap_resource(pdev, 0);
 560         if (IS_ERR(dw_wdt->regs))
 561                 return PTR_ERR(dw_wdt->regs);
 562
 563         /*
 564          * Try to request the watchdog dedicated timer clock source. It must
 565          * be supplied if asynchronous mode is enabled. Otherwise fallback
 566          * to the common timer/bus clocks configuration, in which the very
 567          * first found clock supply both timer and APB signals.
 568          */
 569         dw_wdt->clk = devm_clk_get(dev, "tclk");
 570         if (IS_ERR(dw_wdt->clk)) {
 571                 dw_wdt->clk = devm_clk_get(dev, NULL);
 572                 if (IS_ERR(dw_wdt->clk))
 573                         return PTR_ERR(dw_wdt->clk);
 574         }
 575
 576         ret = clk_prepare_enable(dw_wdt->clk);
 577         if (ret)
 578                 return ret;
 579
 580         dw_wdt->rate = clk_get_rate(dw_wdt->clk);
 581         if (dw_wdt->rate == 0) {
 582                 ret = -EINVAL;
 583                 goto out_disable_clk;
 584         }
 585
 586         /*
 587          * Request APB clock if device is configured with async clocks mode.
 588          * In this case both tclk and pclk clocks are supposed to be specified.
 589          * Alas we can't know for sure whether async mode was really activated,
 590          * so the pclk phandle reference is left optional. If it couldn't be
 591          * found we consider the device configured in synchronous clocks mode.
 592          */
 593         dw_wdt->pclk = devm_clk_get_optional(dev, "pclk");
 594         if (IS_ERR(dw_wdt->pclk)) {
 595                 ret = PTR_ERR(dw_wdt->pclk);
 596                 goto out_disable_clk;
 597         }
 598
 599         ret = clk_prepare_enable(dw_wdt->pclk);
 600         if (ret)
 601                 goto out_disable_clk;
 602
 603         dw_wdt->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
 604         if (IS_ERR(dw_wdt->rst)) {
 605                 ret = PTR_ERR(dw_wdt->rst);
 606                 goto out_disable_pclk;
 607         }
 608
 609         /* Enable normal reset without pre-timeout by default. */
 610         dw_wdt_update_mode(dw_wdt, DW_WDT_RMOD_RESET);
 611
 612         /*
 613          * Pre-timeout IRQ is optional, since some hardware may lack support
 614          * of it. Note we must request rising-edge IRQ, since the lane is left
 615          * pending either until the next watchdog kick event or up to the
 616          * system reset.
 617          */
 618         ret = platform_get_irq_optional(pdev, 0);
 619         if (ret > 0) {
 620                 ret = devm_request_irq(dev, ret, dw_wdt_irq,
 621                                        IRQF_SHARED | IRQF_TRIGGER_RISING,
 622                                        pdev->name, dw_wdt);
 623                 if (ret)
 624                         goto out_disable_pclk;
 625
 626                 dw_wdt->wdd.info = &dw_wdt_pt_ident;
 627         } else {
 628                 if (ret == -EPROBE_DEFER)
 629                         goto out_disable_pclk;
 630
 631                 dw_wdt->wdd.info = &dw_wdt_ident;
 632         }
 633
 634         reset_control_deassert(dw_wdt->rst);
 635
 636         ret = dw_wdt_init_timeouts(dw_wdt, dev);
 637         if (ret)
 638                 goto out_disable_clk;
 639
 640         wdd = &dw_wdt->wdd;
 641         wdd->ops = &dw_wdt_ops;
 642         wdd->min_timeout = dw_wdt_get_min_timeout(dw_wdt);
 643         wdd->max_hw_heartbeat_ms = dw_wdt_get_max_timeout_ms(dw_wdt);
 644         wdd->parent = dev;
 645
 646         watchdog_set_drvdata(wdd, dw_wdt);
 647         watchdog_set_nowayout(wdd, nowayout);
 648         watchdog_init_timeout(wdd, 0, dev);
 649
 650         /*
 651          * If the watchdog is already running, use its already configured
 652          * timeout. Otherwise use the default or the value provided through
 653          * devicetree.
 654          */
 655         if (dw_wdt_is_enabled(dw_wdt)) {
 656                 wdd->timeout = dw_wdt_get_timeout(dw_wdt);
 657                 set_bit(WDOG_HW_RUNNING, &wdd->status);
 658         } else {
 659                 wdd->timeout = DW_WDT_DEFAULT_SECONDS;
 660                 watchdog_init_timeout(wdd, 0, dev);
 661         }
 662
 663         platform_set_drvdata(pdev, dw_wdt);
 664
 665         watchdog_set_restart_priority(wdd, 128);
 666
 667         ret = watchdog_register_device(wdd);
 668         if (ret)
 669                 goto out_disable_pclk;
 670
 671         dw_wdt_dbgfs_init(dw_wdt);
 672
 673         return 0;
 674
 675 out_disable_pclk:
 676         clk_disable_unprepare(dw_wdt->pclk);
 677
 678 out_disable_clk:
 679         clk_disable_unprepare(dw_wdt->clk);
 680         return ret;
 681 }
 682
 683 static int dw_wdt_drv_remove(struct platform_device *pdev)
 684 {
 685         struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);
 686
 687         dw_wdt_dbgfs_clear(dw_wdt);
 688
 689         watchdog_unregister_device(&dw_wdt->wdd);
 690         reset_control_assert(dw_wdt->rst);
 691         clk_disable_unprepare(dw_wdt->pclk);
 692         clk_disable_unprepare(dw_wdt->clk);
 693
 694         return 0;
 695 }
 696
 697 #ifdef CONFIG_OF
 698 static const struct of_device_id dw_wdt_of_match[] = {
 699         { .compatible = "snps,dw-wdt", },
 700         { /* sentinel */ }
 701 };
 702 MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
 703 #endif
 704
 705 static struct platform_driver dw_wdt_driver = {
 706         .probe          = dw_wdt_drv_probe,
 707         .remove         = dw_wdt_drv_remove,
 708         .driver         = {
 709                 .name   = "dw_wdt",
 710                 .of_match_table = of_match_ptr(dw_wdt_of_match),
 711                 .pm     = pm_sleep_ptr(&dw_wdt_pm_ops),
 712         },
 713 };
 714
 715 module_platform_driver(dw_wdt_driver);
 716
 717 MODULE_AUTHOR("Jamie Iles");
 718 MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
 719 MODULE_LICENSE("GPL");