drivers/watchdog/lpc18xx_wdt.c

   1 /*
   2  * NXP LPC18xx Watchdog Timer (WDT)
   3  *
   4  * Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published by
   8  * the Free Software Foundation.
   9  *
  10  * Notes
  11  * -----
  12  * The Watchdog consists of a fixed divide-by-4 clock pre-scaler and a 24-bit
  13  * counter which decrements on every clock cycle.
  14  */
  15
  16 #include <linux/clk.h>
  17 #include <linux/io.h>
  18 #include <linux/module.h>
  19 #include <linux/of.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/watchdog.h>
  22
  23 /* Registers */
  24 #define LPC18XX_WDT_MOD                 0x00
  25 #define LPC18XX_WDT_MOD_WDEN            BIT(0)
  26 #define LPC18XX_WDT_MOD_WDRESET         BIT(1)
  27
  28 #define LPC18XX_WDT_TC                  0x04
  29 #define LPC18XX_WDT_TC_MIN              0xff
  30 #define LPC18XX_WDT_TC_MAX              0xffffff
  31
  32 #define LPC18XX_WDT_FEED                0x08
  33 #define LPC18XX_WDT_FEED_MAGIC1         0xaa
  34 #define LPC18XX_WDT_FEED_MAGIC2         0x55
  35
  36 #define LPC18XX_WDT_TV                  0x0c
  37
  38 /* Clock pre-scaler */
  39 #define LPC18XX_WDT_CLK_DIV             4
  40
  41 /* Timeout values in seconds */
  42 #define LPC18XX_WDT_DEF_TIMEOUT         30U
  43
  44 static int heartbeat;
  45 module_param(heartbeat, int, 0);
  46 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds (default="
  47                  __MODULE_STRING(LPC18XX_WDT_DEF_TIMEOUT) ")");
  48
  49 static bool nowayout = WATCHDOG_NOWAYOUT;
  50 module_param(nowayout, bool, 0);
  51 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  52                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  53
  54 struct lpc18xx_wdt_dev {
  55         struct watchdog_device  wdt_dev;
  56         struct clk              *reg_clk;
  57         struct clk              *wdt_clk;
  58         unsigned long           clk_rate;
  59         void __iomem            *base;
  60         struct timer_list       timer;
  61         spinlock_t              lock;
  62 };
  63
  64 static int lpc18xx_wdt_feed(struct watchdog_device *wdt_dev)
  65 {
  66         struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev);
  67         unsigned long flags;
  68
  69         /*
  70          * An abort condition will occur if an interrupt happens during the feed
  71          * sequence.
  72          */
  73         spin_lock_irqsave(&lpc18xx_wdt->lock, flags);
  74         writel(LPC18XX_WDT_FEED_MAGIC1, lpc18xx_wdt->base + LPC18XX_WDT_FEED);
  75         writel(LPC18XX_WDT_FEED_MAGIC2, lpc18xx_wdt->base + LPC18XX_WDT_FEED);
  76         spin_unlock_irqrestore(&lpc18xx_wdt->lock, flags);
  77
  78         return 0;
  79 }
  80
  81 static void lpc18xx_wdt_timer_feed(unsigned long data)
  82 {
  83         struct watchdog_device *wdt_dev = (struct watchdog_device *)data;
  84         struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev);
  85
  86         lpc18xx_wdt_feed(wdt_dev);
  87
  88         /* Use safe value (1/2 of real timeout) */
  89         mod_timer(&lpc18xx_wdt->timer, jiffies +
  90                   msecs_to_jiffies((wdt_dev->timeout * MSEC_PER_SEC) / 2));
  91 }
  92
  93 /*
  94  * Since LPC18xx Watchdog cannot be disabled in hardware, we must keep feeding
  95  * it with a timer until userspace watchdog software takes over.
  96  */
  97 static int lpc18xx_wdt_stop(struct watchdog_device *wdt_dev)
  98 {
  99         lpc18xx_wdt_timer_feed((unsigned long)wdt_dev);
 100
 101         return 0;
 102 }
 103
 104 static void __lpc18xx_wdt_set_timeout(struct lpc18xx_wdt_dev *lpc18xx_wdt)
 105 {
 106         unsigned int val;
 107
 108         val = DIV_ROUND_UP(lpc18xx_wdt->wdt_dev.timeout * lpc18xx_wdt->clk_rate,
 109                            LPC18XX_WDT_CLK_DIV);
 110         writel(val, lpc18xx_wdt->base + LPC18XX_WDT_TC);
 111 }
 112
 113 static int lpc18xx_wdt_set_timeout(struct watchdog_device *wdt_dev,
 114                                    unsigned int new_timeout)
 115 {
 116         struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev);
 117
 118         lpc18xx_wdt->wdt_dev.timeout = new_timeout;
 119         __lpc18xx_wdt_set_timeout(lpc18xx_wdt);
 120
 121         return 0;
 122 }
 123
 124 static unsigned int lpc18xx_wdt_get_timeleft(struct watchdog_device *wdt_dev)
 125 {
 126         struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev);
 127         unsigned int val;
 128
 129         val = readl(lpc18xx_wdt->base + LPC18XX_WDT_TV);
 130         return (val * LPC18XX_WDT_CLK_DIV) / lpc18xx_wdt->clk_rate;
 131 }
 132
 133 static int lpc18xx_wdt_start(struct watchdog_device *wdt_dev)
 134 {
 135         struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev);
 136         unsigned int val;
 137
 138         if (timer_pending(&lpc18xx_wdt->timer))
 139                 del_timer(&lpc18xx_wdt->timer);
 140
 141         val = readl(lpc18xx_wdt->base + LPC18XX_WDT_MOD);
 142         val |= LPC18XX_WDT_MOD_WDEN;
 143         val |= LPC18XX_WDT_MOD_WDRESET;
 144         writel(val, lpc18xx_wdt->base + LPC18XX_WDT_MOD);
 145
 146         /*
 147          * Setting the WDEN bit in the WDMOD register is not sufficient to
 148          * enable the Watchdog. A valid feed sequence must be completed after
 149          * setting WDEN before the Watchdog is capable of generating a reset.
 150          */
 151         lpc18xx_wdt_feed(wdt_dev);
 152
 153         return 0;
 154 }
 155
 156 static int lpc18xx_wdt_restart(struct watchdog_device *wdt_dev,
 157                                unsigned long action, void *data)
 158 {
 159         struct lpc18xx_wdt_dev *lpc18xx_wdt = watchdog_get_drvdata(wdt_dev);
 160         unsigned long flags;
 161         int val;
 162
 163         /*
 164          * Incorrect feed sequence causes immediate watchdog reset if enabled.
 165          */
 166         spin_lock_irqsave(&lpc18xx_wdt->lock, flags);
 167
 168         val = readl(lpc18xx_wdt->base + LPC18XX_WDT_MOD);
 169         val |= LPC18XX_WDT_MOD_WDEN;
 170         val |= LPC18XX_WDT_MOD_WDRESET;
 171         writel(val, lpc18xx_wdt->base + LPC18XX_WDT_MOD);
 172
 173         writel(LPC18XX_WDT_FEED_MAGIC1, lpc18xx_wdt->base + LPC18XX_WDT_FEED);
 174         writel(LPC18XX_WDT_FEED_MAGIC2, lpc18xx_wdt->base + LPC18XX_WDT_FEED);
 175
 176         writel(LPC18XX_WDT_FEED_MAGIC1, lpc18xx_wdt->base + LPC18XX_WDT_FEED);
 177         writel(LPC18XX_WDT_FEED_MAGIC1, lpc18xx_wdt->base + LPC18XX_WDT_FEED);
 178
 179         spin_unlock_irqrestore(&lpc18xx_wdt->lock, flags);
 180
 181         return 0;
 182 }
 183
 184 static struct watchdog_info lpc18xx_wdt_info = {
 185         .identity       = "NXP LPC18xx Watchdog",
 186         .options        = WDIOF_SETTIMEOUT |
 187                           WDIOF_KEEPALIVEPING |
 188                           WDIOF_MAGICCLOSE,
 189 };
 190
 191 static const struct watchdog_ops lpc18xx_wdt_ops = {
 192         .owner          = THIS_MODULE,
 193         .start          = lpc18xx_wdt_start,
 194         .stop           = lpc18xx_wdt_stop,
 195         .ping           = lpc18xx_wdt_feed,
 196         .set_timeout    = lpc18xx_wdt_set_timeout,
 197         .get_timeleft   = lpc18xx_wdt_get_timeleft,
 198         .restart        = lpc18xx_wdt_restart,
 199 };
 200
 201 static int lpc18xx_wdt_probe(struct platform_device *pdev)
 202 {
 203         struct lpc18xx_wdt_dev *lpc18xx_wdt;
 204         struct device *dev = &pdev->dev;
 205         struct resource *res;
 206         int ret;
 207
 208         lpc18xx_wdt = devm_kzalloc(dev, sizeof(*lpc18xx_wdt), GFP_KERNEL);
 209         if (!lpc18xx_wdt)
 210                 return -ENOMEM;
 211
 212         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 213         lpc18xx_wdt->base = devm_ioremap_resource(dev, res);
 214         if (IS_ERR(lpc18xx_wdt->base))
 215                 return PTR_ERR(lpc18xx_wdt->base);
 216
 217         lpc18xx_wdt->reg_clk = devm_clk_get(dev, "reg");
 218         if (IS_ERR(lpc18xx_wdt->reg_clk)) {
 219                 dev_err(dev, "failed to get the reg clock\n");
 220                 return PTR_ERR(lpc18xx_wdt->reg_clk);
 221         }
 222
 223         lpc18xx_wdt->wdt_clk = devm_clk_get(dev, "wdtclk");
 224         if (IS_ERR(lpc18xx_wdt->wdt_clk)) {
 225                 dev_err(dev, "failed to get the wdt clock\n");
 226                 return PTR_ERR(lpc18xx_wdt->wdt_clk);
 227         }
 228
 229         ret = clk_prepare_enable(lpc18xx_wdt->reg_clk);
 230         if (ret) {
 231                 dev_err(dev, "could not prepare or enable sys clock\n");
 232                 return ret;
 233         }
 234
 235         ret = clk_prepare_enable(lpc18xx_wdt->wdt_clk);
 236         if (ret) {
 237                 dev_err(dev, "could not prepare or enable wdt clock\n");
 238                 goto disable_reg_clk;
 239         }
 240
 241         /* We use the clock rate to calculate timeouts */
 242         lpc18xx_wdt->clk_rate = clk_get_rate(lpc18xx_wdt->wdt_clk);
 243         if (lpc18xx_wdt->clk_rate == 0) {
 244                 dev_err(dev, "failed to get clock rate\n");
 245                 ret = -EINVAL;
 246                 goto disable_wdt_clk;
 247         }
 248
 249         lpc18xx_wdt->wdt_dev.info = &lpc18xx_wdt_info;
 250         lpc18xx_wdt->wdt_dev.ops = &lpc18xx_wdt_ops;
 251
 252         lpc18xx_wdt->wdt_dev.min_timeout = DIV_ROUND_UP(LPC18XX_WDT_TC_MIN *
 253                                 LPC18XX_WDT_CLK_DIV, lpc18xx_wdt->clk_rate);
 254
 255         lpc18xx_wdt->wdt_dev.max_timeout = (LPC18XX_WDT_TC_MAX *
 256                                 LPC18XX_WDT_CLK_DIV) / lpc18xx_wdt->clk_rate;
 257
 258         lpc18xx_wdt->wdt_dev.timeout = min(lpc18xx_wdt->wdt_dev.max_timeout,
 259                                            LPC18XX_WDT_DEF_TIMEOUT);
 260
 261         spin_lock_init(&lpc18xx_wdt->lock);
 262
 263         lpc18xx_wdt->wdt_dev.parent = dev;
 264         watchdog_set_drvdata(&lpc18xx_wdt->wdt_dev, lpc18xx_wdt);
 265
 266         ret = watchdog_init_timeout(&lpc18xx_wdt->wdt_dev, heartbeat, dev);
 267
 268         __lpc18xx_wdt_set_timeout(lpc18xx_wdt);
 269
 270         setup_timer(&lpc18xx_wdt->timer, lpc18xx_wdt_timer_feed,
 271                     (unsigned long)&lpc18xx_wdt->wdt_dev);
 272
 273         watchdog_set_nowayout(&lpc18xx_wdt->wdt_dev, nowayout);
 274         watchdog_set_restart_priority(&lpc18xx_wdt->wdt_dev, 128);
 275
 276         platform_set_drvdata(pdev, lpc18xx_wdt);
 277
 278         ret = watchdog_register_device(&lpc18xx_wdt->wdt_dev);
 279         if (ret)
 280                 goto disable_wdt_clk;
 281
 282         return 0;
 283
 284 disable_wdt_clk:
 285         clk_disable_unprepare(lpc18xx_wdt->wdt_clk);
 286 disable_reg_clk:
 287         clk_disable_unprepare(lpc18xx_wdt->reg_clk);
 288         return ret;
 289 }
 290
 291 static void lpc18xx_wdt_shutdown(struct platform_device *pdev)
 292 {
 293         struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev);
 294
 295         lpc18xx_wdt_stop(&lpc18xx_wdt->wdt_dev);
 296 }
 297
 298 static int lpc18xx_wdt_remove(struct platform_device *pdev)
 299 {
 300         struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev);
 301
 302         dev_warn(&pdev->dev, "I quit now, hardware will probably reboot!\n");
 303         del_timer(&lpc18xx_wdt->timer);
 304
 305         watchdog_unregister_device(&lpc18xx_wdt->wdt_dev);
 306         clk_disable_unprepare(lpc18xx_wdt->wdt_clk);
 307         clk_disable_unprepare(lpc18xx_wdt->reg_clk);
 308
 309         return 0;
 310 }
 311
 312 static const struct of_device_id lpc18xx_wdt_match[] = {
 313         { .compatible = "nxp,lpc1850-wwdt" },
 314         {}
 315 };
 316 MODULE_DEVICE_TABLE(of, lpc18xx_wdt_match);
 317
 318 static struct platform_driver lpc18xx_wdt_driver = {
 319         .driver = {
 320                 .name = "lpc18xx-wdt",
 321                 .of_match_table = lpc18xx_wdt_match,
 322         },
 323         .probe = lpc18xx_wdt_probe,
 324         .remove = lpc18xx_wdt_remove,
 325         .shutdown = lpc18xx_wdt_shutdown,
 326 };
 327 module_platform_driver(lpc18xx_wdt_driver);
 328
 329 MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>");
 330 MODULE_DESCRIPTION("NXP LPC18xx Watchdog Timer Driver");
 331 MODULE_LICENSE("GPL v2");