drivers/watchdog/asm9260_wdt.c

   1 /*
   2  * Watchdog driver for Alphascale ASM9260.
   3  *
   4  * Copyright (c) 2014 Oleksij Rempel <linux@rempel-privat.de>
   5  *
   6  * Licensed under GPLv2 or later.
   7  */
   8
   9 #include <linux/bitops.h>
  10 #include <linux/clk.h>
  11 #include <linux/delay.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/io.h>
  14 #include <linux/module.h>
  15 #include <linux/of.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/reboot.h>
  18 #include <linux/reset.h>
  19 #include <linux/watchdog.h>
  20
  21 #define CLOCK_FREQ      1000000
  22
  23 /* Watchdog Mode register */
  24 #define HW_WDMOD                        0x00
  25 /* Wake interrupt. Set by HW, can't be cleared. */
  26 #define BM_MOD_WDINT                    BIT(3)
  27 /* This bit set if timeout reached. Cleared by SW. */
  28 #define BM_MOD_WDTOF                    BIT(2)
  29 /* HW Reset on timeout */
  30 #define BM_MOD_WDRESET                  BIT(1)
  31 /* WD enable */
  32 #define BM_MOD_WDEN                     BIT(0)
  33
  34 /*
  35  * Watchdog Timer Constant register
  36  * Minimal value is 0xff, the meaning of this value
  37  * depends on used clock: T = WDCLK * (0xff + 1) * 4
  38  */
  39 #define HW_WDTC                         0x04
  40 #define BM_WDTC_MAX(freq)               (0x7fffffff / (freq))
  41
  42 /* Watchdog Feed register */
  43 #define HW_WDFEED                       0x08
  44
  45 /* Watchdog Timer Value register */
  46 #define HW_WDTV                         0x0c
  47
  48 #define ASM9260_WDT_DEFAULT_TIMEOUT     30
  49
  50 enum asm9260_wdt_mode {
  51         HW_RESET,
  52         SW_RESET,
  53         DEBUG,
  54 };
  55
  56 struct asm9260_wdt_priv {
  57         struct device           *dev;
  58         struct watchdog_device  wdd;
  59         struct clk              *clk;
  60         struct clk              *clk_ahb;
  61         struct reset_control    *rst;
  62         struct notifier_block   restart_handler;
  63
  64         void __iomem            *iobase;
  65         int                     irq;
  66         unsigned long           wdt_freq;
  67         enum asm9260_wdt_mode   mode;
  68 };
  69
  70 static int asm9260_wdt_feed(struct watchdog_device *wdd)
  71 {
  72         struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
  73
  74         iowrite32(0xaa, priv->iobase + HW_WDFEED);
  75         iowrite32(0x55, priv->iobase + HW_WDFEED);
  76
  77         return 0;
  78 }
  79
  80 static unsigned int asm9260_wdt_gettimeleft(struct watchdog_device *wdd)
  81 {
  82         struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
  83         u32 counter;
  84
  85         counter = ioread32(priv->iobase + HW_WDTV);
  86
  87         return DIV_ROUND_CLOSEST(counter, priv->wdt_freq);
  88 }
  89
  90 static int asm9260_wdt_updatetimeout(struct watchdog_device *wdd)
  91 {
  92         struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
  93         u32 counter;
  94
  95         counter = wdd->timeout * priv->wdt_freq;
  96
  97         iowrite32(counter, priv->iobase + HW_WDTC);
  98
  99         return 0;
 100 }
 101
 102 static int asm9260_wdt_enable(struct watchdog_device *wdd)
 103 {
 104         struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
 105         u32 mode = 0;
 106
 107         if (priv->mode == HW_RESET)
 108                 mode = BM_MOD_WDRESET;
 109
 110         iowrite32(BM_MOD_WDEN | mode, priv->iobase + HW_WDMOD);
 111
 112         asm9260_wdt_updatetimeout(wdd);
 113
 114         asm9260_wdt_feed(wdd);
 115
 116         return 0;
 117 }
 118
 119 static int asm9260_wdt_disable(struct watchdog_device *wdd)
 120 {
 121         struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
 122
 123         /* The only way to disable WD is to reset it. */
 124         reset_control_assert(priv->rst);
 125         reset_control_deassert(priv->rst);
 126
 127         return 0;
 128 }
 129
 130 static int asm9260_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
 131 {
 132         wdd->timeout = to;
 133         asm9260_wdt_updatetimeout(wdd);
 134
 135         return 0;
 136 }
 137
 138 static void asm9260_wdt_sys_reset(struct asm9260_wdt_priv *priv)
 139 {
 140         /* init WD if it was not started */
 141
 142         iowrite32(BM_MOD_WDEN | BM_MOD_WDRESET, priv->iobase + HW_WDMOD);
 143
 144         iowrite32(0xff, priv->iobase + HW_WDTC);
 145         /* first pass correct sequence */
 146         asm9260_wdt_feed(&priv->wdd);
 147         /*
 148          * Then write wrong pattern to the feed to trigger reset
 149          * ASAP.
 150          */
 151         iowrite32(0xff, priv->iobase + HW_WDFEED);
 152
 153         mdelay(1000);
 154 }
 155
 156 static irqreturn_t asm9260_wdt_irq(int irq, void *devid)
 157 {
 158         struct asm9260_wdt_priv *priv = devid;
 159         u32 stat;
 160
 161         stat = ioread32(priv->iobase + HW_WDMOD);
 162         if (!(stat & BM_MOD_WDINT))
 163                 return IRQ_NONE;
 164
 165         if (priv->mode == DEBUG) {
 166                 dev_info(priv->dev, "Watchdog Timeout. Do nothing.\n");
 167         } else {
 168                 dev_info(priv->dev, "Watchdog Timeout. Doing SW Reset.\n");
 169                 asm9260_wdt_sys_reset(priv);
 170         }
 171
 172         return IRQ_HANDLED;
 173 }
 174
 175 static int asm9260_restart_handler(struct notifier_block *this,
 176                                    unsigned long mode, void *cmd)
 177 {
 178         struct asm9260_wdt_priv *priv =
 179                 container_of(this, struct asm9260_wdt_priv, restart_handler);
 180
 181         asm9260_wdt_sys_reset(priv);
 182
 183         return NOTIFY_DONE;
 184 }
 185
 186 static const struct watchdog_info asm9260_wdt_ident = {
 187         .options          =     WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING
 188                                 | WDIOF_MAGICCLOSE,
 189         .identity         =     "Alphascale asm9260 Watchdog",
 190 };
 191
 192 static struct watchdog_ops asm9260_wdt_ops = {
 193         .owner          = THIS_MODULE,
 194         .start          = asm9260_wdt_enable,
 195         .stop           = asm9260_wdt_disable,
 196         .get_timeleft   = asm9260_wdt_gettimeleft,
 197         .ping           = asm9260_wdt_feed,
 198         .set_timeout    = asm9260_wdt_settimeout,
 199 };
 200
 201 static int asm9260_wdt_get_dt_clks(struct asm9260_wdt_priv *priv)
 202 {
 203         int err;
 204         unsigned long clk;
 205
 206         priv->clk = devm_clk_get(priv->dev, "mod");
 207         if (IS_ERR(priv->clk)) {
 208                 dev_err(priv->dev, "Failed to get \"mod\" clk\n");
 209                 return PTR_ERR(priv->clk);
 210         }
 211
 212         /* configure AHB clock */
 213         priv->clk_ahb = devm_clk_get(priv->dev, "ahb");
 214         if (IS_ERR(priv->clk_ahb)) {
 215                 dev_err(priv->dev, "Failed to get \"ahb\" clk\n");
 216                 return PTR_ERR(priv->clk_ahb);
 217         }
 218
 219         err = clk_prepare_enable(priv->clk_ahb);
 220         if (err) {
 221                 dev_err(priv->dev, "Failed to enable ahb_clk!\n");
 222                 return err;
 223         }
 224
 225         err = clk_set_rate(priv->clk, CLOCK_FREQ);
 226         if (err) {
 227                 clk_disable_unprepare(priv->clk_ahb);
 228                 dev_err(priv->dev, "Failed to set rate!\n");
 229                 return err;
 230         }
 231
 232         err = clk_prepare_enable(priv->clk);
 233         if (err) {
 234                 clk_disable_unprepare(priv->clk_ahb);
 235                 dev_err(priv->dev, "Failed to enable clk!\n");
 236                 return err;
 237         }
 238
 239         /* wdt has internal divider */
 240         clk = clk_get_rate(priv->clk);
 241         if (!clk) {
 242                 clk_disable_unprepare(priv->clk);
 243                 clk_disable_unprepare(priv->clk_ahb);
 244                 dev_err(priv->dev, "Failed, clk is 0!\n");
 245                 return -EINVAL;
 246         }
 247
 248         priv->wdt_freq = clk / 2;
 249
 250         return 0;
 251 }
 252
 253 static void asm9260_wdt_get_dt_mode(struct asm9260_wdt_priv *priv)
 254 {
 255         const char *tmp;
 256         int ret;
 257
 258         /* default mode */
 259         priv->mode = HW_RESET;
 260
 261         ret = of_property_read_string(priv->dev->of_node,
 262                                       "alphascale,mode", &tmp);
 263         if (ret < 0)
 264                 return;
 265
 266         if (!strcmp(tmp, "hw"))
 267                 priv->mode = HW_RESET;
 268         else if (!strcmp(tmp, "sw"))
 269                 priv->mode = SW_RESET;
 270         else if (!strcmp(tmp, "debug"))
 271                 priv->mode = DEBUG;
 272         else
 273                 dev_warn(priv->dev, "unknown reset-type: %s. Using default \"hw\" mode.",
 274                          tmp);
 275 }
 276
 277 static int asm9260_wdt_probe(struct platform_device *pdev)
 278 {
 279         struct asm9260_wdt_priv *priv;
 280         struct watchdog_device *wdd;
 281         struct resource *res;
 282         int ret;
 283         const char * const mode_name[] = { "hw", "sw", "debug", };
 284
 285         priv = devm_kzalloc(&pdev->dev, sizeof(struct asm9260_wdt_priv),
 286                             GFP_KERNEL);
 287         if (!priv)
 288                 return -ENOMEM;
 289
 290         priv->dev = &pdev->dev;
 291
 292         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 293         priv->iobase = devm_ioremap_resource(&pdev->dev, res);
 294         if (IS_ERR(priv->iobase))
 295                 return PTR_ERR(priv->iobase);
 296
 297         ret = asm9260_wdt_get_dt_clks(priv);
 298         if (ret)
 299                 return ret;
 300
 301         priv->rst = devm_reset_control_get(&pdev->dev, "wdt_rst");
 302         if (IS_ERR(priv->rst))
 303                 return PTR_ERR(priv->rst);
 304
 305         wdd = &priv->wdd;
 306         wdd->info = &asm9260_wdt_ident;
 307         wdd->ops = &asm9260_wdt_ops;
 308         wdd->min_timeout = 1;
 309         wdd->max_timeout = BM_WDTC_MAX(priv->wdt_freq);
 310         wdd->parent = &pdev->dev;
 311
 312         watchdog_set_drvdata(wdd, priv);
 313
 314         /*
 315          * If 'timeout-sec' unspecified in devicetree, assume a 30 second
 316          * default, unless the max timeout is less than 30 seconds, then use
 317          * the max instead.
 318          */
 319         wdd->timeout = ASM9260_WDT_DEFAULT_TIMEOUT;
 320         watchdog_init_timeout(wdd, 0, &pdev->dev);
 321
 322         asm9260_wdt_get_dt_mode(priv);
 323
 324         if (priv->mode != HW_RESET)
 325                 priv->irq = platform_get_irq(pdev, 0);
 326
 327         if (priv->irq > 0) {
 328                 /*
 329                  * Not all supported platforms specify an interrupt for the
 330                  * watchdog, so let's make it optional.
 331                  */
 332                 ret = devm_request_irq(&pdev->dev, priv->irq,
 333                                        asm9260_wdt_irq, 0, pdev->name, priv);
 334                 if (ret < 0)
 335                         dev_warn(&pdev->dev, "failed to request IRQ\n");
 336         }
 337
 338         ret = watchdog_register_device(wdd);
 339         if (ret)
 340                 goto clk_off;
 341
 342         platform_set_drvdata(pdev, priv);
 343
 344         priv->restart_handler.notifier_call = asm9260_restart_handler;
 345         priv->restart_handler.priority = 128;
 346         ret = register_restart_handler(&priv->restart_handler);
 347         if (ret)
 348                 dev_warn(&pdev->dev, "cannot register restart handler\n");
 349
 350         dev_info(&pdev->dev, "Watchdog enabled (timeout: %d sec, mode: %s)\n",
 351                  wdd->timeout, mode_name[priv->mode]);
 352         return 0;
 353
 354 clk_off:
 355         clk_disable_unprepare(priv->clk);
 356         clk_disable_unprepare(priv->clk_ahb);
 357         return ret;
 358 }
 359
 360 static void asm9260_wdt_shutdown(struct platform_device *pdev)
 361 {
 362         struct asm9260_wdt_priv *priv = platform_get_drvdata(pdev);
 363
 364         asm9260_wdt_disable(&priv->wdd);
 365 }
 366
 367 static int asm9260_wdt_remove(struct platform_device *pdev)
 368 {
 369         struct asm9260_wdt_priv *priv = platform_get_drvdata(pdev);
 370
 371         asm9260_wdt_disable(&priv->wdd);
 372
 373         unregister_restart_handler(&priv->restart_handler);
 374
 375         watchdog_unregister_device(&priv->wdd);
 376
 377         clk_disable_unprepare(priv->clk);
 378         clk_disable_unprepare(priv->clk_ahb);
 379
 380         return 0;
 381 }
 382
 383 static const struct of_device_id asm9260_wdt_of_match[] = {
 384         { .compatible = "alphascale,asm9260-wdt"},
 385         {},
 386 };
 387 MODULE_DEVICE_TABLE(of, asm9260_wdt_of_match);
 388
 389 static struct platform_driver asm9260_wdt_driver = {
 390         .driver = {
 391                 .name = "asm9260-wdt",
 392                 .owner = THIS_MODULE,
 393                 .of_match_table = asm9260_wdt_of_match,
 394         },
 395         .probe = asm9260_wdt_probe,
 396         .remove = asm9260_wdt_remove,
 397         .shutdown = asm9260_wdt_shutdown,
 398 };
 399 module_platform_driver(asm9260_wdt_driver);
 400
 401 MODULE_DESCRIPTION("asm9260 WatchDog Timer Driver");
 402 MODULE_AUTHOR("Oleksij Rempel <linux@rempel-privat.de>");
 403 MODULE_LICENSE("GPL");