drivers/reset/reset-meson.c

   1 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
   2 /*
   3  * Amlogic Meson Reset Controller driver
   4  *
   5  * Copyright (c) 2016 BayLibre, SAS.
   6  * Author: Neil Armstrong <narmstrong@baylibre.com>
   7  */
   8 #include <linux/err.h>
   9 #include <linux/init.h>
  10 #include <linux/io.h>
  11 #include <linux/of.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/reset-controller.h>
  14 #include <linux/slab.h>
  15 #include <linux/types.h>
  16 #include <linux/of_device.h>
  17
  18 #define REG_COUNT       8
  19 #define BITS_PER_REG    32
  20 #define LEVEL_OFFSET    0x7c
  21
  22 struct meson_reset {
  23         void __iomem *reg_base;
  24         struct reset_controller_dev rcdev;
  25         spinlock_t lock;
  26 };
  27
  28 static int meson_reset_reset(struct reset_controller_dev *rcdev,
  29                               unsigned long id)
  30 {
  31         struct meson_reset *data =
  32                 container_of(rcdev, struct meson_reset, rcdev);
  33         unsigned int bank = id / BITS_PER_REG;
  34         unsigned int offset = id % BITS_PER_REG;
  35         void __iomem *reg_addr = data->reg_base + (bank << 2);
  36
  37         writel(BIT(offset), reg_addr);
  38
  39         return 0;
  40 }
  41
  42 static int meson_reset_level(struct reset_controller_dev *rcdev,
  43                             unsigned long id, bool assert)
  44 {
  45         struct meson_reset *data =
  46                 container_of(rcdev, struct meson_reset, rcdev);
  47         unsigned int bank = id / BITS_PER_REG;
  48         unsigned int offset = id % BITS_PER_REG;
  49         void __iomem *reg_addr = data->reg_base + LEVEL_OFFSET + (bank << 2);
  50         unsigned long flags;
  51         u32 reg;
  52
  53         spin_lock_irqsave(&data->lock, flags);
  54
  55         reg = readl(reg_addr);
  56         if (assert)
  57                 writel(reg & ~BIT(offset), reg_addr);
  58         else
  59                 writel(reg | BIT(offset), reg_addr);
  60
  61         spin_unlock_irqrestore(&data->lock, flags);
  62
  63         return 0;
  64 }
  65
  66 static int meson_reset_assert(struct reset_controller_dev *rcdev,
  67                               unsigned long id)
  68 {
  69         return meson_reset_level(rcdev, id, true);
  70 }
  71
  72 static int meson_reset_deassert(struct reset_controller_dev *rcdev,
  73                                 unsigned long id)
  74 {
  75         return meson_reset_level(rcdev, id, false);
  76 }
  77
  78 static const struct reset_control_ops meson_reset_ops = {
  79         .reset          = meson_reset_reset,
  80         .assert         = meson_reset_assert,
  81         .deassert       = meson_reset_deassert,
  82 };
  83
  84 static const struct of_device_id meson_reset_dt_ids[] = {
  85          { .compatible = "amlogic,meson8b-reset" },
  86          { .compatible = "amlogic,meson-gxbb-reset" },
  87          { .compatible = "amlogic,meson-axg-reset" },
  88          { /* sentinel */ },
  89 };
  90
  91 static int meson_reset_probe(struct platform_device *pdev)
  92 {
  93         struct meson_reset *data;
  94         struct resource *res;
  95
  96         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
  97         if (!data)
  98                 return -ENOMEM;
  99
 100         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 101         data->reg_base = devm_ioremap_resource(&pdev->dev, res);
 102         if (IS_ERR(data->reg_base))
 103                 return PTR_ERR(data->reg_base);
 104
 105         platform_set_drvdata(pdev, data);
 106
 107         spin_lock_init(&data->lock);
 108
 109         data->rcdev.owner = THIS_MODULE;
 110         data->rcdev.nr_resets = REG_COUNT * BITS_PER_REG;
 111         data->rcdev.ops = &meson_reset_ops;
 112         data->rcdev.of_node = pdev->dev.of_node;
 113
 114         return devm_reset_controller_register(&pdev->dev, &data->rcdev);
 115 }
 116
 117 static struct platform_driver meson_reset_driver = {
 118         .probe  = meson_reset_probe,
 119         .driver = {
 120                 .name           = "meson_reset",
 121                 .of_match_table = meson_reset_dt_ids,
 122         },
 123 };
 124 builtin_platform_driver(meson_reset_driver);