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/platform_device.h>
  18 #include <linux/pm_runtime.h>
  19 #include <linux/types.h>
  20 #include <linux/watchdog.h>
  21
  22 #define DEFAULT_HEARTBEAT 60
  23
  24 /* Max heartbeat is calculated at 32kHz source clock */
  25 #define MAX_HEARTBEAT   1000
  26
  27 /* Timer register set definition */
  28 #define RTIDWDCTRL      0x90
  29 #define RTIDWDPRLD      0x94
  30 #define RTIWDSTATUS     0x98
  31 #define RTIWDKEY        0x9c
  32 #define RTIDWDCNTR      0xa0
  33 #define RTIWWDRXCTRL    0xa4
  34 #define RTIWWDSIZECTRL  0xa8
  35
  36 #define RTIWWDRX_NMI    0xa
  37
  38 #define RTIWWDSIZE_50P          0x50
  39 #define RTIWWDSIZE_25P          0x500
  40 #define RTIWWDSIZE_12P5         0x5000
  41 #define RTIWWDSIZE_6P25         0x50000
  42 #define RTIWWDSIZE_3P125        0x500000
  43
  44 #define WDENABLE_KEY    0xa98559da
  45
  46 #define WDKEY_SEQ0              0xe51a
  47 #define WDKEY_SEQ1              0xa35c
  48
  49 #define WDT_PRELOAD_SHIFT       13
  50
  51 #define WDT_PRELOAD_MAX         0xfff
  52
  53 #define DWDST                   BIT(1)
  54
  55 static int heartbeat = DEFAULT_HEARTBEAT;
  56
  57 /*
  58  * struct to hold data for each WDT device
  59  * @base - base io address of WD device
  60  * @freq - source clock frequency of WDT
  61  * @wdd  - hold watchdog device as is in WDT core
  62  */
  63 struct rti_wdt_device {
  64         void __iomem            *base;
  65         unsigned long           freq;
  66         struct watchdog_device  wdd;
  67 };
  68
  69 static int rti_wdt_start(struct watchdog_device *wdd)
  70 {
  71         u32 timer_margin;
  72         struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
  73         int ret;
  74
  75         ret = pm_runtime_resume_and_get(wdd->parent);
  76         if (ret)
  77                 return ret;
  78
  79         /* set timeout period */
  80         timer_margin = (u64)wdd->timeout * wdt->freq;
  81         timer_margin >>= WDT_PRELOAD_SHIFT;
  82         if (timer_margin > WDT_PRELOAD_MAX)
  83                 timer_margin = WDT_PRELOAD_MAX;
  84         writel_relaxed(timer_margin, wdt->base + RTIDWDPRLD);
  85
  86         /*
  87          * RTI only supports a windowed mode, where the watchdog can only
  88          * be petted during the open window; not too early or not too late.
  89          * The HW configuration options only allow for the open window size
  90          * to be 50% or less than that; we obviouly want to configure the open
  91          * window as large as possible so we select the 50% option.
  92          */
  93         wdd->min_hw_heartbeat_ms = 500 * wdd->timeout;
  94
  95         /* Generate NMI when wdt expires */
  96         writel_relaxed(RTIWWDRX_NMI, wdt->base + RTIWWDRXCTRL);
  97
  98         /* Open window size 50%; this is the largest window size available */
  99         writel_relaxed(RTIWWDSIZE_50P, wdt->base + RTIWWDSIZECTRL);
 100
 101         readl_relaxed(wdt->base + RTIWWDSIZECTRL);
 102
 103         /* enable watchdog */
 104         writel_relaxed(WDENABLE_KEY, wdt->base + RTIDWDCTRL);
 105         return 0;
 106 }
 107
 108 static int rti_wdt_ping(struct watchdog_device *wdd)
 109 {
 110         struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
 111
 112         /* put watchdog in service state */
 113         writel_relaxed(WDKEY_SEQ0, wdt->base + RTIWDKEY);
 114         /* put watchdog in active state */
 115         writel_relaxed(WDKEY_SEQ1, wdt->base + RTIWDKEY);
 116
 117         return 0;
 118 }
 119
 120 static int rti_wdt_setup_hw_hb(struct watchdog_device *wdd, u32 wsize)
 121 {
 122         /*
 123          * RTI only supports a windowed mode, where the watchdog can only
 124          * be petted during the open window; not too early or not too late.
 125          * The HW configuration options only allow for the open window size
 126          * to be 50% or less than that.
 127          */
 128         switch (wsize) {
 129         case RTIWWDSIZE_50P:
 130                 /* 50% open window => 50% min heartbeat */
 131                 wdd->min_hw_heartbeat_ms = 500 * heartbeat;
 132                 break;
 133
 134         case RTIWWDSIZE_25P:
 135                 /* 25% open window => 75% min heartbeat */
 136                 wdd->min_hw_heartbeat_ms = 750 * heartbeat;
 137                 break;
 138
 139         case RTIWWDSIZE_12P5:
 140                 /* 12.5% open window => 87.5% min heartbeat */
 141                 wdd->min_hw_heartbeat_ms = 875 * heartbeat;
 142                 break;
 143
 144         case RTIWWDSIZE_6P25:
 145                 /* 6.5% open window => 93.5% min heartbeat */
 146                 wdd->min_hw_heartbeat_ms = 935 * heartbeat;
 147                 break;
 148
 149         case RTIWWDSIZE_3P125:
 150                 /* 3.125% open window => 96.9% min heartbeat */
 151                 wdd->min_hw_heartbeat_ms = 969 * heartbeat;
 152                 break;
 153
 154         default:
 155                 return -EINVAL;
 156         }
 157
 158         return 0;
 159 }
 160
 161 static unsigned int rti_wdt_get_timeleft_ms(struct watchdog_device *wdd)
 162 {
 163         u64 timer_counter;
 164         u32 val;
 165         struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
 166
 167         /* if timeout has occurred then return 0 */
 168         val = readl_relaxed(wdt->base + RTIWDSTATUS);
 169         if (val & DWDST)
 170                 return 0;
 171
 172         timer_counter = readl_relaxed(wdt->base + RTIDWDCNTR);
 173
 174         timer_counter *= 1000;
 175
 176         do_div(timer_counter, wdt->freq);
 177
 178         return timer_counter;
 179 }
 180
 181 static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd)
 182 {
 183         return rti_wdt_get_timeleft_ms(wdd) / 1000;
 184 }
 185
 186 static const struct watchdog_info rti_wdt_info = {
 187         .options = WDIOF_KEEPALIVEPING,
 188         .identity = "K3 RTI Watchdog",
 189 };
 190
 191 static const struct watchdog_ops rti_wdt_ops = {
 192         .owner          = THIS_MODULE,
 193         .start          = rti_wdt_start,
 194         .ping           = rti_wdt_ping,
 195         .get_timeleft   = rti_wdt_get_timeleft,
 196 };
 197
 198 static int rti_wdt_probe(struct platform_device *pdev)
 199 {
 200         int ret = 0;
 201         struct device *dev = &pdev->dev;
 202         struct resource *wdt_mem;
 203         struct watchdog_device *wdd;
 204         struct rti_wdt_device *wdt;
 205         struct clk *clk;
 206         u32 last_ping = 0;
 207
 208         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 209         if (!wdt)
 210                 return -ENOMEM;
 211
 212         clk = clk_get(dev, NULL);
 213         if (IS_ERR(clk))
 214                 return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n");
 215
 216         wdt->freq = clk_get_rate(clk);
 217
 218         clk_put(clk);
 219
 220         if (!wdt->freq) {
 221                 dev_err(dev, "Failed to get fck rate.\n");
 222                 return -EINVAL;
 223         }
 224
 225         /*
 226          * If watchdog is running at 32k clock, it is not accurate.
 227          * Adjust frequency down in this case so that we don't pet
 228          * the watchdog too often.
 229          */
 230         if (wdt->freq < 32768)
 231                 wdt->freq = wdt->freq * 9 / 10;
 232
 233         pm_runtime_enable(dev);
 234         ret = pm_runtime_get_sync(dev);
 235         if (ret < 0) {
 236                 pm_runtime_put_noidle(dev);
 237                 pm_runtime_disable(&pdev->dev);
 238                 return dev_err_probe(dev, ret, "runtime pm failed\n");
 239         }
 240
 241         platform_set_drvdata(pdev, wdt);
 242
 243         wdd = &wdt->wdd;
 244         wdd->info = &rti_wdt_info;
 245         wdd->ops = &rti_wdt_ops;
 246         wdd->min_timeout = 1;
 247         wdd->max_hw_heartbeat_ms = (WDT_PRELOAD_MAX << WDT_PRELOAD_SHIFT) /
 248                 wdt->freq * 1000;
 249         wdd->parent = dev;
 250
 251         watchdog_set_drvdata(wdd, wdt);
 252         watchdog_set_nowayout(wdd, 1);
 253         watchdog_set_restart_priority(wdd, 128);
 254
 255         wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 256         wdt->base = devm_ioremap_resource(dev, wdt_mem);
 257         if (IS_ERR(wdt->base)) {
 258                 ret = PTR_ERR(wdt->base);
 259                 goto err_iomap;
 260         }
 261
 262         if (readl(wdt->base + RTIDWDCTRL) == WDENABLE_KEY) {
 263                 u32 time_left_ms;
 264                 u64 heartbeat_ms;
 265                 u32 wsize;
 266
 267                 set_bit(WDOG_HW_RUNNING, &wdd->status);
 268                 time_left_ms = rti_wdt_get_timeleft_ms(wdd);
 269                 heartbeat_ms = readl(wdt->base + RTIDWDPRLD);
 270                 heartbeat_ms <<= WDT_PRELOAD_SHIFT;
 271                 heartbeat_ms *= 1000;
 272                 do_div(heartbeat_ms, wdt->freq);
 273                 if (heartbeat_ms != heartbeat * 1000)
 274                         dev_warn(dev, "watchdog already running, ignoring heartbeat config!\n");
 275
 276                 heartbeat = heartbeat_ms;
 277                 heartbeat /= 1000;
 278
 279                 wsize = readl(wdt->base + RTIWWDSIZECTRL);
 280                 ret = rti_wdt_setup_hw_hb(wdd, wsize);
 281                 if (ret) {
 282                         dev_err(dev, "bad window size.\n");
 283                         goto err_iomap;
 284                 }
 285
 286                 last_ping = heartbeat_ms - time_left_ms;
 287                 if (time_left_ms > heartbeat_ms) {
 288                         dev_warn(dev, "time_left > heartbeat? Assuming last ping just before now.\n");
 289                         last_ping = 0;
 290                 }
 291         }
 292
 293         watchdog_init_timeout(wdd, heartbeat, dev);
 294
 295         ret = watchdog_register_device(wdd);
 296         if (ret) {
 297                 dev_err(dev, "cannot register watchdog device\n");
 298                 goto err_iomap;
 299         }
 300
 301         if (last_ping)
 302                 watchdog_set_last_hw_keepalive(wdd, last_ping);
 303
 304         if (!watchdog_hw_running(wdd))
 305                 pm_runtime_put_sync(&pdev->dev);
 306
 307         return 0;
 308
 309 err_iomap:
 310         pm_runtime_put_sync(&pdev->dev);
 311         pm_runtime_disable(&pdev->dev);
 312
 313         return ret;
 314 }
 315
 316 static int rti_wdt_remove(struct platform_device *pdev)
 317 {
 318         struct rti_wdt_device *wdt = platform_get_drvdata(pdev);
 319
 320         watchdog_unregister_device(&wdt->wdd);
 321
 322         if (!pm_runtime_suspended(&pdev->dev))
 323                 pm_runtime_put(&pdev->dev);
 324
 325         pm_runtime_disable(&pdev->dev);
 326
 327         return 0;
 328 }
 329
 330 static const struct of_device_id rti_wdt_of_match[] = {
 331         { .compatible = "ti,j7-rti-wdt", },
 332         {},
 333 };
 334 MODULE_DEVICE_TABLE(of, rti_wdt_of_match);
 335
 336 static struct platform_driver rti_wdt_driver = {
 337         .driver = {
 338                 .name = "rti-wdt",
 339                 .of_match_table = rti_wdt_of_match,
 340         },
 341         .probe = rti_wdt_probe,
 342         .remove = rti_wdt_remove,
 343 };
 344
 345 module_platform_driver(rti_wdt_driver);
 346
 347 MODULE_AUTHOR("Tero Kristo <t-kristo@ti.com>");
 348 MODULE_DESCRIPTION("K3 RTI Watchdog Driver");
 349
 350 module_param(heartbeat, int, 0);
 351 MODULE_PARM_DESC(heartbeat,
 352                  "Watchdog heartbeat period in seconds from 1 to "
 353                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 354                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 355
 356 MODULE_LICENSE("GPL");
 357 MODULE_ALIAS("platform:rti-wdt");