drivers/reset/reset-meson.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Amlogic Meson Reset Controller driver
   4  *
   5  * Copyright (c) 2018 BayLibre, SAS.
   6  * Author: Neil Armstrong <narmstrong@baylibre.com>
   7  */
   8
   9 #include <common.h>
  10 #include <dm.h>
  11 #include <malloc.h>
  12 #include <reset-uclass.h>
  13 #include <regmap.h>
  14
  15 #define REG_COUNT       8
  16 #define BITS_PER_REG    32
  17 #define LEVEL_OFFSET    0x7c
  18
  19 struct meson_reset_priv {
  20         struct regmap *regmap;
  21 };
  22
  23 static int meson_reset_request(struct reset_ctl *reset_ctl)
  24 {
  25         if (reset_ctl->id > (REG_COUNT * BITS_PER_REG))
  26                 return -EINVAL;
  27
  28         return 0;
  29 }
  30
  31 static int meson_reset_free(struct reset_ctl *reset_ctl)
  32 {
  33         return 0;
  34 }
  35
  36 static int meson_reset_level(struct reset_ctl *reset_ctl, bool assert)
  37 {
  38         struct meson_reset_priv *priv = dev_get_priv(reset_ctl->dev);
  39         uint bank = reset_ctl->id / BITS_PER_REG;
  40         uint offset = reset_ctl->id % BITS_PER_REG;
  41         uint reg_offset = LEVEL_OFFSET + (bank << 2);
  42         uint val;
  43
  44         regmap_read(priv->regmap, reg_offset, &val);
  45         if (assert)
  46                 val &= ~BIT(offset);
  47         else
  48                 val |= BIT(offset);
  49         regmap_write(priv->regmap, reg_offset, val);
  50
  51         return 0;
  52 }
  53
  54 static int meson_reset_assert(struct reset_ctl *reset_ctl)
  55 {
  56         return meson_reset_level(reset_ctl, true);
  57 }
  58
  59 static int meson_reset_deassert(struct reset_ctl *reset_ctl)
  60 {
  61         return meson_reset_level(reset_ctl, false);
  62 }
  63
  64 struct reset_ops meson_reset_ops = {
  65         .request = meson_reset_request,
  66         .rfree = meson_reset_free,
  67         .rst_assert = meson_reset_assert,
  68         .rst_deassert = meson_reset_deassert,
  69 };
  70
  71 static const struct udevice_id meson_reset_ids[] = {
  72         { .compatible = "amlogic,meson-gxbb-reset" },
  73         { .compatible = "amlogic,meson-axg-reset" },
  74         { }
  75 };
  76
  77 static int meson_reset_probe(struct udevice *dev)
  78 {
  79         struct meson_reset_priv *priv = dev_get_priv(dev);
  80
  81         return regmap_init_mem(dev_ofnode(dev), &priv->regmap);
  82 }
  83
  84 U_BOOT_DRIVER(meson_reset) = {
  85         .name = "meson_reset",
  86         .id = UCLASS_RESET,
  87         .of_match = meson_reset_ids,
  88         .probe = meson_reset_probe,
  89         .ops = &meson_reset_ops,
  90         .priv_auto_alloc_size = sizeof(struct meson_reset_priv),
  91 };