linux/drivers/reset/reset-bcm6345.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * BCM6345 Reset Controller Driver
   4 *
   5 * Copyright (C) 2020 \xC3\x81lvaro Fern\xC3\xA1ndez Rojas <noltari@gmail.com>
   6 */
   7
   8#include <linux/delay.h>
   9#include <linux/init.h>
  10#include <linux/io.h>
  11#include <linux/mod_devicetable.h>
  12#include <linux/platform_device.h>
  13#include <linux/reset-controller.h>
  14
  15#define BCM6345_RESET_NUM               32
  16#define BCM6345_RESET_SLEEP_MIN_US      10000
  17#define BCM6345_RESET_SLEEP_MAX_US      20000
  18
  19struct bcm6345_reset {
  20        struct reset_controller_dev rcdev;
  21        void __iomem *base;
  22        spinlock_t lock;
  23};
  24
  25static inline struct bcm6345_reset *
  26to_bcm6345_reset(struct reset_controller_dev *rcdev)
  27{
  28        return container_of(rcdev, struct bcm6345_reset, rcdev);
  29}
  30
  31static int bcm6345_reset_update(struct reset_controller_dev *rcdev,
  32                                unsigned long id, bool assert)
  33{
  34        struct bcm6345_reset *bcm6345_reset = to_bcm6345_reset(rcdev);
  35        unsigned long flags;
  36        uint32_t val;
  37
  38        spin_lock_irqsave(&bcm6345_reset->lock, flags);
  39        val = __raw_readl(bcm6345_reset->base);
  40        if (assert)
  41                val &= ~BIT(id);
  42        else
  43                val |= BIT(id);
  44        __raw_writel(val, bcm6345_reset->base);
  45        spin_unlock_irqrestore(&bcm6345_reset->lock, flags);
  46
  47        return 0;
  48}
  49
  50static int bcm6345_reset_assert(struct reset_controller_dev *rcdev,
  51                                unsigned long id)
  52{
  53        return bcm6345_reset_update(rcdev, id, true);
  54}
  55
  56static int bcm6345_reset_deassert(struct reset_controller_dev *rcdev,
  57                                  unsigned long id)
  58{
  59        return bcm6345_reset_update(rcdev, id, false);
  60}
  61
  62static int bcm6345_reset_reset(struct reset_controller_dev *rcdev,
  63                               unsigned long id)
  64{
  65        bcm6345_reset_update(rcdev, id, true);
  66        usleep_range(BCM6345_RESET_SLEEP_MIN_US,
  67                     BCM6345_RESET_SLEEP_MAX_US);
  68
  69        bcm6345_reset_update(rcdev, id, false);
  70        /*
  71         * Ensure component is taken out reset state by sleeping also after
  72         * deasserting the reset. Otherwise, the component may not be ready
  73         * for operation.
  74         */
  75        usleep_range(BCM6345_RESET_SLEEP_MIN_US,
  76                     BCM6345_RESET_SLEEP_MAX_US);
  77
  78        return 0;
  79}
  80
  81static int bcm6345_reset_status(struct reset_controller_dev *rcdev,
  82                                unsigned long id)
  83{
  84        struct bcm6345_reset *bcm6345_reset = to_bcm6345_reset(rcdev);
  85
  86        return !(__raw_readl(bcm6345_reset->base) & BIT(id));
  87}
  88
  89static const struct reset_control_ops bcm6345_reset_ops = {
  90        .assert = bcm6345_reset_assert,
  91        .deassert = bcm6345_reset_deassert,
  92        .reset = bcm6345_reset_reset,
  93        .status = bcm6345_reset_status,
  94};
  95
  96static int bcm6345_reset_probe(struct platform_device *pdev)
  97{
  98        struct bcm6345_reset *bcm6345_reset;
  99
 100        bcm6345_reset = devm_kzalloc(&pdev->dev,
 101                                     sizeof(*bcm6345_reset), GFP_KERNEL);
 102        if (!bcm6345_reset)
 103                return -ENOMEM;
 104
 105        platform_set_drvdata(pdev, bcm6345_reset);
 106
 107        bcm6345_reset->base = devm_platform_ioremap_resource(pdev, 0);
 108        if (IS_ERR(bcm6345_reset->base))
 109                return PTR_ERR(bcm6345_reset->base);
 110
 111        spin_lock_init(&bcm6345_reset->lock);
 112        bcm6345_reset->rcdev.ops = &bcm6345_reset_ops;
 113        bcm6345_reset->rcdev.owner = THIS_MODULE;
 114        bcm6345_reset->rcdev.of_node = pdev->dev.of_node;
 115        bcm6345_reset->rcdev.of_reset_n_cells = 1;
 116        bcm6345_reset->rcdev.nr_resets = BCM6345_RESET_NUM;
 117
 118        return devm_reset_controller_register(&pdev->dev,
 119                                              &bcm6345_reset->rcdev);
 120}
 121
 122static const struct of_device_id bcm6345_reset_of_match[] = {
 123        { .compatible = "brcm,bcm6345-reset" },
 124        { /* sentinel */ },
 125};
 126
 127static struct platform_driver bcm6345_reset_driver = {
 128        .probe = bcm6345_reset_probe,
 129        .driver = {
 130                .name = "bcm6345-reset",
 131                .of_match_table = bcm6345_reset_of_match,
 132                .suppress_bind_attrs = true,
 133        },
 134};
 135builtin_platform_driver(bcm6345_reset_driver);
 136