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 static int heartbeat = DEFAULT_HEARTBEAT;
  63
  64 /*
  65  * struct to hold data for each WDT device
  66  * @base - base io address of WD device
  67  * @freq - source clock frequency of WDT
  68  * @wdd  - hold watchdog device as is in WDT core
  69  */
  70 struct rti_wdt_device {
  71         void __iomem            *base;
  72         unsigned long           freq;
  73         struct watchdog_device  wdd;
  74 };
  75
  76 static int rti_wdt_start(struct watchdog_device *wdd)
  77 {
  78         u32 timer_margin;
  79         struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
  80
  81         /* set timeout period */
  82         timer_margin = (u64)wdd->timeout * wdt->freq;
  83         timer_margin >>= WDT_PRELOAD_SHIFT;
  84         if (timer_margin > WDT_PRELOAD_MAX)
  85                 timer_margin = WDT_PRELOAD_MAX;
  86         writel_relaxed(timer_margin, wdt->base + RTIDWDPRLD);
  87
  88         /*
  89          * RTI only supports a windowed mode, where the watchdog can only
  90          * be petted during the open window; not too early or not too late.
  91          * The HW configuration options only allow for the open window size
  92          * to be 50% or less than that; we obviouly want to configure the open
  93          * window as large as possible so we select the 50% option.
  94          */
  95         wdd->min_hw_heartbeat_ms = 500 * wdd->timeout;
  96
  97         /* Generate NMI when wdt expires */
  98         writel_relaxed(RTIWWDRX_NMI, wdt->base + RTIWWDRXCTRL);
  99
 100         /* Open window size 50%; this is the largest window size available */
 101         writel_relaxed(RTIWWDSIZE_50P, wdt->base + RTIWWDSIZECTRL);
 102
 103         readl_relaxed(wdt->base + RTIWWDSIZECTRL);
 104
 105         /* enable watchdog */
 106         writel_relaxed(WDENABLE_KEY, wdt->base + RTIDWDCTRL);
 107         return 0;
 108 }
 109
 110 static int rti_wdt_ping(struct watchdog_device *wdd)
 111 {
 112         struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
 113
 114         /* put watchdog in service state */
 115         writel_relaxed(WDKEY_SEQ0, wdt->base + RTIWDKEY);
 116         /* put watchdog in active state */
 117         writel_relaxed(WDKEY_SEQ1, wdt->base + RTIWDKEY);
 118
 119         return 0;
 120 }
 121
 122 static int rti_wdt_setup_hw_hb(struct watchdog_device *wdd, u32 wsize)
 123 {
 124         /*
 125          * RTI only supports a windowed mode, where the watchdog can only
 126          * be petted during the open window; not too early or not too late.
 127          * The HW configuration options only allow for the open window size
 128          * to be 50% or less than that.
 129          */
 130         switch (wsize) {
 131         case RTIWWDSIZE_50P:
 132                 /* 50% open window => 50% min heartbeat */
 133                 wdd->min_hw_heartbeat_ms = 500 * heartbeat;
 134                 break;
 135
 136         case RTIWWDSIZE_25P:
 137                 /* 25% open window => 75% min heartbeat */
 138                 wdd->min_hw_heartbeat_ms = 750 * heartbeat;
 139                 break;
 140
 141         case RTIWWDSIZE_12P5:
 142                 /* 12.5% open window => 87.5% min heartbeat */
 143                 wdd->min_hw_heartbeat_ms = 875 * heartbeat;
 144                 break;
 145
 146         case RTIWWDSIZE_6P25:
 147                 /* 6.5% open window => 93.5% min heartbeat */
 148                 wdd->min_hw_heartbeat_ms = 935 * heartbeat;
 149                 break;
 150
 151         case RTIWWDSIZE_3P125:
 152                 /* 3.125% open window => 96.9% min heartbeat */
 153                 wdd->min_hw_heartbeat_ms = 969 * heartbeat;
 154                 break;
 155
 156         default:
 157                 return -EINVAL;
 158         }
 159
 160         return 0;
 161 }
 162
 163 static unsigned int rti_wdt_get_timeleft_ms(struct watchdog_device *wdd)
 164 {
 165         u64 timer_counter;
 166         u32 val;
 167         struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
 168
 169         /* if timeout has occurred then return 0 */
 170         val = readl_relaxed(wdt->base + RTIWDSTATUS);
 171         if (val & DWDST)
 172                 return 0;
 173
 174         timer_counter = readl_relaxed(wdt->base + RTIDWDCNTR);
 175
 176         timer_counter *= 1000;
 177
 178         do_div(timer_counter, wdt->freq);
 179
 180         return timer_counter;
 181 }
 182
 183 static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd)
 184 {
 185         return rti_wdt_get_timeleft_ms(wdd) / 1000;
 186 }
 187
 188 static const struct watchdog_info rti_wdt_info = {
 189         .options = WDIOF_KEEPALIVEPING,
 190         .identity = "K3 RTI Watchdog",
 191 };
 192
 193 static const struct watchdog_ops rti_wdt_ops = {
 194         .owner          = THIS_MODULE,
 195         .start          = rti_wdt_start,
 196         .ping           = rti_wdt_ping,
 197         .get_timeleft   = rti_wdt_get_timeleft,
 198 };
 199
 200 static int rti_wdt_probe(struct platform_device *pdev)
 201 {
 202         int ret = 0;
 203         struct device *dev = &pdev->dev;
 204         struct watchdog_device *wdd;
 205         struct rti_wdt_device *wdt;
 206         struct clk *clk;
 207         u32 last_ping = 0;
 208         struct device_node *node;
 209         u32 reserved_mem_size;
 210         struct resource res;
 211         u32 *vaddr;
 212         u64 paddr;
 213
 214         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 215         if (!wdt)
 216                 return -ENOMEM;
 217
 218         clk = clk_get(dev, NULL);
 219         if (IS_ERR(clk))
 220                 return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n");
 221
 222         wdt->freq = clk_get_rate(clk);
 223
 224         clk_put(clk);
 225
 226         if (!wdt->freq) {
 227                 dev_err(dev, "Failed to get fck rate.\n");
 228                 return -EINVAL;
 229         }
 230
 231         /*
 232          * If watchdog is running at 32k clock, it is not accurate.
 233          * Adjust frequency down in this case so that we don't pet
 234          * the watchdog too often.
 235          */
 236         if (wdt->freq < 32768)
 237                 wdt->freq = wdt->freq * 9 / 10;
 238
 239         pm_runtime_enable(dev);
 240         ret = pm_runtime_resume_and_get(dev);
 241         if (ret < 0) {
 242                 pm_runtime_disable(&pdev->dev);
 243                 return dev_err_probe(dev, ret, "runtime pm failed\n");
 244         }
 245
 246         platform_set_drvdata(pdev, wdt);
 247
 248         wdd = &wdt->wdd;
 249         wdd->info = &rti_wdt_info;
 250         wdd->ops = &rti_wdt_ops;
 251         wdd->min_timeout = 1;
 252         wdd->max_hw_heartbeat_ms = (WDT_PRELOAD_MAX << WDT_PRELOAD_SHIFT) /
 253                 wdt->freq * 1000;
 254         wdd->parent = dev;
 255
 256         watchdog_set_drvdata(wdd, wdt);
 257         watchdog_set_nowayout(wdd, 1);
 258         watchdog_set_restart_priority(wdd, 128);
 259
 260         wdt->base = devm_platform_ioremap_resource(pdev, 0);
 261         if (IS_ERR(wdt->base)) {
 262                 ret = PTR_ERR(wdt->base);
 263                 goto err_iomap;
 264         }
 265
 266         if (readl(wdt->base + RTIDWDCTRL) == WDENABLE_KEY) {
 267                 int preset_heartbeat;
 268                 u32 time_left_ms;
 269                 u64 heartbeat_ms;
 270                 u32 wsize;
 271
 272                 set_bit(WDOG_HW_RUNNING, &wdd->status);
 273                 time_left_ms = rti_wdt_get_timeleft_ms(wdd);
 274                 heartbeat_ms = readl(wdt->base + RTIDWDPRLD);
 275                 heartbeat_ms <<= WDT_PRELOAD_SHIFT;
 276                 heartbeat_ms *= 1000;
 277                 do_div(heartbeat_ms, wdt->freq);
 278                 preset_heartbeat = heartbeat_ms + 500;
 279                 preset_heartbeat /= 1000;
 280                 if (preset_heartbeat != heartbeat)
 281                         dev_warn(dev, "watchdog already running, ignoring heartbeat config!\n");
 282
 283                 heartbeat = preset_heartbeat;
 284
 285                 wsize = readl(wdt->base + RTIWWDSIZECTRL);
 286                 ret = rti_wdt_setup_hw_hb(wdd, wsize);
 287                 if (ret) {
 288                         dev_err(dev, "bad window size.\n");
 289                         goto err_iomap;
 290                 }
 291
 292                 last_ping = heartbeat_ms - time_left_ms;
 293                 if (time_left_ms > heartbeat_ms) {
 294                         dev_warn(dev, "time_left > heartbeat? Assuming last ping just before now.\n");
 295                         last_ping = 0;
 296                 }
 297         }
 298
 299         node = of_parse_phandle(pdev->dev.of_node, "memory-region", 0);
 300         if (node) {
 301                 ret = of_address_to_resource(node, 0, &res);
 302                 if (ret) {
 303                         dev_err(dev, "No memory address assigned to the region.\n");
 304                         goto err_iomap;
 305                 }
 306
 307                 /*
 308                  * If reserved memory is defined for watchdog reset cause.
 309                  * Readout the Power-on(PON) reason and pass to bootstatus.
 310                  */
 311                 paddr = res.start;
 312                 reserved_mem_size = resource_size(&res);
 313                 if (reserved_mem_size < RESERVED_MEM_MIN_SIZE) {
 314                         dev_err(dev, "The size of reserved memory is too small.\n");
 315                         ret = -EINVAL;
 316                         goto err_iomap;
 317                 }
 318
 319                 vaddr = memremap(paddr, reserved_mem_size, MEMREMAP_WB);
 320                 if (!vaddr) {
 321                         dev_err(dev, "Failed to map memory-region.\n");
 322                         ret = -ENOMEM;
 323                         goto err_iomap;
 324                 }
 325
 326                 if (vaddr[0] == PON_REASON_SOF_NUM &&
 327                     vaddr[1] == PON_REASON_MAGIC_NUM &&
 328                     vaddr[2] == PON_REASON_EOF_NUM) {
 329                         wdd->bootstatus |= WDIOF_CARDRESET;
 330                 }
 331                 memset(vaddr, 0, reserved_mem_size);
 332                 memunmap(vaddr);
 333         }
 334
 335         watchdog_init_timeout(wdd, heartbeat, dev);
 336
 337         ret = watchdog_register_device(wdd);
 338         if (ret) {
 339                 dev_err(dev, "cannot register watchdog device\n");
 340                 goto err_iomap;
 341         }
 342
 343         if (last_ping)
 344                 watchdog_set_last_hw_keepalive(wdd, last_ping);
 345
 346         return 0;
 347
 348 err_iomap:
 349         pm_runtime_put_sync(&pdev->dev);
 350         pm_runtime_disable(&pdev->dev);
 351
 352         return ret;
 353 }
 354
 355 static void rti_wdt_remove(struct platform_device *pdev)
 356 {
 357         struct rti_wdt_device *wdt = platform_get_drvdata(pdev);
 358
 359         watchdog_unregister_device(&wdt->wdd);
 360         pm_runtime_put(&pdev->dev);
 361         pm_runtime_disable(&pdev->dev);
 362 }
 363
 364 static const struct of_device_id rti_wdt_of_match[] = {
 365         { .compatible = "ti,j7-rti-wdt", },
 366         {},
 367 };
 368 MODULE_DEVICE_TABLE(of, rti_wdt_of_match);
 369
 370 static struct platform_driver rti_wdt_driver = {
 371         .driver = {
 372                 .name = "rti-wdt",
 373                 .of_match_table = rti_wdt_of_match,
 374         },
 375         .probe = rti_wdt_probe,
 376         .remove_new = rti_wdt_remove,
 377 };
 378
 379 module_platform_driver(rti_wdt_driver);
 380
 381 MODULE_AUTHOR("Tero Kristo <t-kristo@ti.com>");
 382 MODULE_DESCRIPTION("K3 RTI Watchdog Driver");
 383
 384 module_param(heartbeat, int, 0);
 385 MODULE_PARM_DESC(heartbeat,
 386                  "Watchdog heartbeat period in seconds from 1 to "
 387                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 388                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 389
 390 MODULE_LICENSE("GPL");
 391 MODULE_ALIAS("platform:rti-wdt");