drivers/watchdog/apple_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2021 Mark Kettenis <kettenis@openbsd.org>
   4  */
   5
   6 #include <clk.h>
   7 #include <dm.h>
   8 #include <wdt.h>
   9 #include <asm/io.h>
  10 #include <linux/delay.h>
  11
  12 #define APPLE_WDT_CUR_TIME              0x10
  13 #define APPLE_WDT_BARK_TIME             0x14
  14 #define APPLE_WDT_CTRL                  0x1c
  15 #define  APPLE_WDT_CTRL_RESET_EN        BIT(2)
  16
  17 struct apple_wdt_priv {
  18         void *base;
  19         ulong clk_rate;
  20 };
  21
  22 static int apple_wdt_reset(struct udevice *dev)
  23 {
  24         struct apple_wdt_priv *priv = dev_get_priv(dev);
  25
  26         writel(0, priv->base + APPLE_WDT_CUR_TIME);
  27
  28         return 0;
  29 }
  30
  31 static int apple_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
  32 {
  33         struct apple_wdt_priv *priv = dev_get_priv(dev);
  34         u64 timeout;
  35
  36         timeout = (timeout_ms * priv->clk_rate) / 1000;
  37         if (timeout > U32_MAX)
  38                 return -EINVAL;
  39
  40         writel(0, priv->base + APPLE_WDT_CUR_TIME);
  41         writel(timeout, priv->base + APPLE_WDT_BARK_TIME);
  42         writel(APPLE_WDT_CTRL_RESET_EN, priv->base + APPLE_WDT_CTRL);
  43
  44         return 0;
  45 }
  46
  47 static int apple_wdt_stop(struct udevice *dev)
  48 {
  49         struct apple_wdt_priv *priv = dev_get_priv(dev);
  50
  51         writel(0, priv->base + APPLE_WDT_CTRL);
  52
  53         return 0;
  54 }
  55
  56 static int apple_wdt_expire_now(struct udevice *dev, ulong flags)
  57 {
  58         int ret;
  59
  60         ret = apple_wdt_start(dev, 0, flags);
  61         if (ret)
  62                 return ret;
  63
  64         /*
  65          * It can take up to 25ms until the SoC actually resets, so
  66          * wait 50ms just to be sure.
  67          */
  68         mdelay(50);
  69
  70         return 0;
  71 }
  72
  73 static const struct wdt_ops apple_wdt_ops = {
  74         .reset = apple_wdt_reset,
  75         .start = apple_wdt_start,
  76         .stop = apple_wdt_stop,
  77         .expire_now = apple_wdt_expire_now,
  78 };
  79
  80 static const struct udevice_id apple_wdt_ids[] = {
  81         { .compatible = "apple,wdt" },
  82         { /* sentinel */ }
  83 };
  84
  85 static int apple_wdt_probe(struct udevice *dev)
  86 {
  87         struct apple_wdt_priv *priv = dev_get_priv(dev);
  88         struct clk clk;
  89         int ret;
  90
  91         priv->base = dev_read_addr_ptr(dev);
  92         if (!priv->base)
  93                 return -EINVAL;
  94
  95         ret = clk_get_by_index(dev, 0, &clk);
  96         if (ret)
  97                 return ret;
  98
  99         ret = clk_enable(&clk);
 100         if (ret)
 101                 return ret;
 102
 103         priv->clk_rate = clk_get_rate(&clk);
 104
 105         return 0;
 106 }
 107
 108 U_BOOT_DRIVER(apple_wdt) = {
 109         .name = "apple_wdt",
 110         .id = UCLASS_WDT,
 111         .of_match = apple_wdt_ids,
 112         .priv_auto = sizeof(struct apple_wdt_priv),
 113         .probe = apple_wdt_probe,
 114         .ops = &apple_wdt_ops,
 115 };