drivers/watchdog/rti_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Watchdog driver for the K3 RTI module
   4  *
   5  * (c) Copyright 2019-2020 Texas Instruments Inc.
   6  * All rights reserved.
   7  */
   8
   9 #include <linux/clk.h>
  10 #include <linux/device.h>
  11 #include <linux/err.h>
  12 #include <linux/io.h>
  13 #include <linux/kernel.h>
  14 #include <linux/mod_devicetable.h>
  15 #include <linux/module.h>
  16 #include <linux/moduleparam.h>
  17 #include <linux/of.h>
  18 #include <linux/of_address.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/pm_runtime.h>
  21 #include <linux/types.h>
  22 #include <linux/watchdog.h>
  23
  24 #define DEFAULT_HEARTBEAT 60
  25
  26 /* Max heartbeat is calculated at 32kHz source clock */
  27 #define MAX_HEARTBEAT   1000
  28
  29 /* Timer register set definition */
  30 #define RTIDWDCTRL      0x90
  31 #define RTIDWDPRLD      0x94
  32 #define RTIWDSTATUS     0x98
  33 #define RTIWDKEY        0x9c
  34 #define RTIDWDCNTR      0xa0
  35 #define RTIWWDRXCTRL    0xa4
  36 #define RTIWWDSIZECTRL  0xa8
  37
  38 #define RTIWWDRX_NMI    0xa
  39
  40 #define RTIWWDSIZE_50P          0x50
  41 #define RTIWWDSIZE_25P          0x500
  42 #define RTIWWDSIZE_12P5         0x5000
  43 #define RTIWWDSIZE_6P25         0x50000
  44 #define RTIWWDSIZE_3P125        0x500000
  45
  46 #define WDENABLE_KEY    0xa98559da
  47
  48 #define WDKEY_SEQ0              0xe51a
  49 #define WDKEY_SEQ1              0xa35c
  50
  51 #define WDT_PRELOAD_SHIFT       13
  52
  53 #define WDT_PRELOAD_MAX         0xfff
  54
  55 #define DWDST                   BIT(1)
  56
  57 #define PON_REASON_SOF_NUM      0xBBBBCCCC
  58 #define PON_REASON_MAGIC_NUM    0xDDDDDDDD
  59 #define PON_REASON_EOF_NUM      0xCCCCBBBB
  60 #define RESERVED_MEM_MIN_SIZE   12
  61
  62 #define MAX_HW_ERROR            250
  63
  64 static int heartbeat = DEFAULT_HEARTBEAT;
  65
  66 /*
  67  * struct to hold data for each WDT device
  68  * @base - base io address of WD device
  69  * @freq - source clock frequency of WDT
  70  * @wdd  - hold watchdog device as is in WDT core
  71  */
  72 struct rti_wdt_device {
  73         void __iomem            *base;
  74         unsigned long           freq;
  75         struct watchdog_device  wdd;
  76 };
  77
  78 static int rti_wdt_start(struct watchdog_device *wdd)
  79 {
  80         u32 timer_margin;
  81         struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
  82         int ret;
  83
  84         ret = pm_runtime_resume_and_get(wdd->parent);
  85         if (ret)
  86                 return ret;
  87
  88         /* set timeout period */
  89         timer_margin = (u64)wdd->timeout * wdt->freq;
  90         timer_margin >>= WDT_PRELOAD_SHIFT;
  91         if (timer_margin > WDT_PRELOAD_MAX)
  92                 timer_margin = WDT_PRELOAD_MAX;
  93         writel_relaxed(timer_margin, wdt->base + RTIDWDPRLD);
  94
  95         /*
  96          * RTI only supports a windowed mode, where the watchdog can only
  97          * be petted during the open window; not too early or not too late.
  98          * The HW configuration options only allow for the open window size
  99          * to be 50% or less than that; we obviouly want to configure the open
 100          * window as large as possible so we select the 50% option.
 101          */
 102         wdd->min_hw_heartbeat_ms = 520 * wdd->timeout + MAX_HW_ERROR;
 103
 104         /* Generate NMI when wdt expires */
 105         writel_relaxed(RTIWWDRX_NMI, wdt->base + RTIWWDRXCTRL);
 106
 107         /* Open window size 50%; this is the largest window size available */
 108         writel_relaxed(RTIWWDSIZE_50P, wdt->base + RTIWWDSIZECTRL);
 109
 110         readl_relaxed(wdt->base + RTIWWDSIZECTRL);
 111
 112         /* enable watchdog */
 113         writel_relaxed(WDENABLE_KEY, wdt->base + RTIDWDCTRL);
 114         return 0;
 115 }
 116
 117 static int rti_wdt_ping(struct watchdog_device *wdd)
 118 {
 119         struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
 120
 121         /* put watchdog in service state */
 122         writel_relaxed(WDKEY_SEQ0, wdt->base + RTIWDKEY);
 123         /* put watchdog in active state */
 124         writel_relaxed(WDKEY_SEQ1, wdt->base + RTIWDKEY);
 125
 126         return 0;
 127 }
 128
 129 static int rti_wdt_setup_hw_hb(struct watchdog_device *wdd, u32 wsize)
 130 {
 131         /*
 132          * RTI only supports a windowed mode, where the watchdog can only
 133          * be petted during the open window; not too early or not too late.
 134          * The HW configuration options only allow for the open window size
 135          * to be 50% or less than that.
 136          * To avoid any glitches, we accommodate 2% + max hardware error
 137          * safety margin.
 138          */
 139         switch (wsize) {
 140         case RTIWWDSIZE_50P:
 141                 /* 50% open window => 52% min heartbeat */
 142                 wdd->min_hw_heartbeat_ms = 520 * heartbeat + MAX_HW_ERROR;
 143                 break;
 144
 145         case RTIWWDSIZE_25P:
 146                 /* 25% open window => 77% min heartbeat */
 147                 wdd->min_hw_heartbeat_ms = 770 * heartbeat + MAX_HW_ERROR;
 148                 break;
 149
 150         case RTIWWDSIZE_12P5:
 151                 /* 12.5% open window => 89.5% min heartbeat */
 152                 wdd->min_hw_heartbeat_ms = 895 * heartbeat + MAX_HW_ERROR;
 153                 break;
 154
 155         case RTIWWDSIZE_6P25:
 156                 /* 6.5% open window => 95.5% min heartbeat */
 157                 wdd->min_hw_heartbeat_ms = 955 * heartbeat + MAX_HW_ERROR;
 158                 break;
 159
 160         case RTIWWDSIZE_3P125:
 161                 /* 3.125% open window => 98.9% min heartbeat */
 162                 wdd->min_hw_heartbeat_ms = 989 * heartbeat + MAX_HW_ERROR;
 163                 break;
 164
 165         default:
 166                 return -EINVAL;
 167         }
 168
 169         return 0;
 170 }
 171
 172 static unsigned int rti_wdt_get_timeleft_ms(struct watchdog_device *wdd)
 173 {
 174         u64 timer_counter;
 175         u32 val;
 176         struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
 177
 178         /* if timeout has occurred then return 0 */
 179         val = readl_relaxed(wdt->base + RTIWDSTATUS);
 180         if (val & DWDST)
 181                 return 0;
 182
 183         timer_counter = readl_relaxed(wdt->base + RTIDWDCNTR);
 184
 185         timer_counter *= 1000;
 186
 187         do_div(timer_counter, wdt->freq);
 188
 189         return timer_counter;
 190 }
 191
 192 static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd)
 193 {
 194         return rti_wdt_get_timeleft_ms(wdd) / 1000;
 195 }
 196
 197 static const struct watchdog_info rti_wdt_info = {
 198         .options = WDIOF_KEEPALIVEPING,
 199         .identity = "K3 RTI Watchdog",
 200 };
 201
 202 static const struct watchdog_ops rti_wdt_ops = {
 203         .owner          = THIS_MODULE,
 204         .start          = rti_wdt_start,
 205         .ping           = rti_wdt_ping,
 206         .get_timeleft   = rti_wdt_get_timeleft,
 207 };
 208
 209 static int rti_wdt_probe(struct platform_device *pdev)
 210 {
 211         int ret = 0;
 212         struct device *dev = &pdev->dev;
 213         struct watchdog_device *wdd;
 214         struct rti_wdt_device *wdt;
 215         struct clk *clk;
 216         u32 last_ping = 0;
 217         struct device_node *node;
 218         u32 reserved_mem_size;
 219         struct resource res;
 220         u32 *vaddr;
 221         u64 paddr;
 222
 223         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 224         if (!wdt)
 225                 return -ENOMEM;
 226
 227         clk = clk_get(dev, NULL);
 228         if (IS_ERR(clk))
 229                 return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n");
 230
 231         wdt->freq = clk_get_rate(clk);
 232
 233         clk_put(clk);
 234
 235         if (!wdt->freq) {
 236                 dev_err(dev, "Failed to get fck rate.\n");
 237                 return -EINVAL;
 238         }
 239
 240         pm_runtime_enable(dev);
 241         ret = pm_runtime_resume_and_get(dev);
 242         if (ret < 0) {
 243                 pm_runtime_disable(&pdev->dev);
 244                 return dev_err_probe(dev, ret, "runtime pm failed\n");
 245         }
 246
 247         platform_set_drvdata(pdev, wdt);
 248
 249         wdd = &wdt->wdd;
 250         wdd->info = &rti_wdt_info;
 251         wdd->ops = &rti_wdt_ops;
 252         wdd->min_timeout = 1;
 253         wdd->max_hw_heartbeat_ms = (WDT_PRELOAD_MAX << WDT_PRELOAD_SHIFT) /
 254                 wdt->freq * 1000;
 255         wdd->parent = dev;
 256
 257         watchdog_set_drvdata(wdd, wdt);
 258         watchdog_set_nowayout(wdd, 1);
 259         watchdog_set_restart_priority(wdd, 128);
 260
 261         wdt->base = devm_platform_ioremap_resource(pdev, 0);
 262         if (IS_ERR(wdt->base)) {
 263                 ret = PTR_ERR(wdt->base);
 264                 goto err_iomap;
 265         }
 266
 267         if (readl(wdt->base + RTIDWDCTRL) == WDENABLE_KEY) {
 268                 int preset_heartbeat;
 269                 u32 time_left_ms;
 270                 u64 heartbeat_ms;
 271                 u32 wsize;
 272
 273                 set_bit(WDOG_HW_RUNNING, &wdd->status);
 274                 time_left_ms = rti_wdt_get_timeleft_ms(wdd);
 275                 heartbeat_ms = readl(wdt->base + RTIDWDPRLD);
 276                 heartbeat_ms <<= WDT_PRELOAD_SHIFT;
 277                 heartbeat_ms *= 1000;
 278                 do_div(heartbeat_ms, wdt->freq);
 279                 preset_heartbeat = heartbeat_ms + 500;
 280                 preset_heartbeat /= 1000;
 281                 if (preset_heartbeat != heartbeat)
 282                         dev_warn(dev, "watchdog already running, ignoring heartbeat config!\n");
 283
 284                 heartbeat = preset_heartbeat;
 285
 286                 wsize = readl(wdt->base + RTIWWDSIZECTRL);
 287                 ret = rti_wdt_setup_hw_hb(wdd, wsize);
 288                 if (ret) {
 289                         dev_err(dev, "bad window size.\n");
 290                         goto err_iomap;
 291                 }
 292
 293                 last_ping = heartbeat_ms - time_left_ms;
 294                 if (time_left_ms > heartbeat_ms) {
 295                         dev_warn(dev, "time_left > heartbeat? Assuming last ping just before now.\n");
 296                         last_ping = 0;
 297                 }
 298         }
 299
 300         node = of_parse_phandle(pdev->dev.of_node, "memory-region", 0);
 301         if (node) {
 302                 ret = of_address_to_resource(node, 0, &res);
 303                 if (ret) {
 304                         dev_err(dev, "No memory address assigned to the region.\n");
 305                         goto err_iomap;
 306                 }
 307
 308                 /*
 309                  * If reserved memory is defined for watchdog reset cause.
 310                  * Readout the Power-on(PON) reason and pass to bootstatus.
 311                  */
 312                 paddr = res.start;
 313                 reserved_mem_size = resource_size(&res);
 314                 if (reserved_mem_size < RESERVED_MEM_MIN_SIZE) {
 315                         dev_err(dev, "The size of reserved memory is too small.\n");
 316                         ret = -EINVAL;
 317                         goto err_iomap;
 318                 }
 319
 320                 vaddr = memremap(paddr, reserved_mem_size, MEMREMAP_WB);
 321                 if (!vaddr) {
 322                         dev_err(dev, "Failed to map memory-region.\n");
 323                         ret = -ENOMEM;
 324                         goto err_iomap;
 325                 }
 326
 327                 if (vaddr[0] == PON_REASON_SOF_NUM &&
 328                     vaddr[1] == PON_REASON_MAGIC_NUM &&
 329                     vaddr[2] == PON_REASON_EOF_NUM) {
 330                         wdd->bootstatus |= WDIOF_CARDRESET;
 331                 }
 332                 memset(vaddr, 0, reserved_mem_size);
 333                 memunmap(vaddr);
 334         }
 335
 336         watchdog_init_timeout(wdd, heartbeat, dev);
 337
 338         ret = watchdog_register_device(wdd);
 339         if (ret) {
 340                 dev_err(dev, "cannot register watchdog device\n");
 341                 goto err_iomap;
 342         }
 343
 344         if (last_ping)
 345                 watchdog_set_last_hw_keepalive(wdd, last_ping);
 346
 347         if (!watchdog_hw_running(wdd))
 348                 pm_runtime_put_sync(&pdev->dev);
 349
 350         return 0;
 351
 352 err_iomap:
 353         pm_runtime_put_sync(&pdev->dev);
 354         pm_runtime_disable(&pdev->dev);
 355
 356         return ret;
 357 }
 358
 359 static void rti_wdt_remove(struct platform_device *pdev)
 360 {
 361         struct rti_wdt_device *wdt = platform_get_drvdata(pdev);
 362
 363         watchdog_unregister_device(&wdt->wdd);
 364
 365         if (!pm_runtime_suspended(&pdev->dev))
 366                 pm_runtime_put(&pdev->dev);
 367
 368         pm_runtime_disable(&pdev->dev);
 369 }
 370
 371 static const struct of_device_id rti_wdt_of_match[] = {
 372         { .compatible = "ti,j7-rti-wdt", },
 373         {},
 374 };
 375 MODULE_DEVICE_TABLE(of, rti_wdt_of_match);
 376
 377 static struct platform_driver rti_wdt_driver = {
 378         .driver = {
 379                 .name = "rti-wdt",
 380                 .of_match_table = rti_wdt_of_match,
 381         },
 382         .probe = rti_wdt_probe,
 383         .remove_new = rti_wdt_remove,
 384 };
 385
 386 module_platform_driver(rti_wdt_driver);
 387
 388 MODULE_AUTHOR("Tero Kristo <[email protected]>");
 389 MODULE_DESCRIPTION("K3 RTI Watchdog Driver");
 390
 391 module_param(heartbeat, int, 0);
 392 MODULE_PARM_DESC(heartbeat,
 393                  "Watchdog heartbeat period in seconds from 1 to "
 394                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 395                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 396
 397 MODULE_LICENSE("GPL");
 398 MODULE_ALIAS("platform:rti-wdt");