linux/drivers/reset/reset-meson.c
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   1/*
   2 * Amlogic Meson Reset Controller driver
   3 *
   4 * This file is provided under a dual BSD/GPLv2 license.  When using or
   5 * redistributing this file, you may do so under either license.
   6 *
   7 * GPL LICENSE SUMMARY
   8 *
   9 * Copyright (c) 2016 BayLibre, SAS.
  10 * Author: Neil Armstrong <narmstrong@baylibre.com>
  11 *
  12 * This program is free software; you can redistribute it and/or modify
  13 * it under the terms of version 2 of the GNU General Public License as
  14 * published by the Free Software Foundation.
  15 *
  16 * This program is distributed in the hope that it will be useful, but
  17 * WITHOUT ANY WARRANTY; without even the implied warranty of
  18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19 * General Public License for more details.
  20 *
  21 * You should have received a copy of the GNU General Public License
  22 * along with this program; if not, see <http://www.gnu.org/licenses/>.
  23 * The full GNU General Public License is included in this distribution
  24 * in the file called COPYING.
  25 *
  26 * BSD LICENSE
  27 *
  28 * Copyright (c) 2016 BayLibre, SAS.
  29 * Author: Neil Armstrong <narmstrong@baylibre.com>
  30 *
  31 * Redistribution and use in source and binary forms, with or without
  32 * modification, are permitted provided that the following conditions
  33 * are met:
  34 *
  35 *   * Redistributions of source code must retain the above copyright
  36 *     notice, this list of conditions and the following disclaimer.
  37 *   * Redistributions in binary form must reproduce the above copyright
  38 *     notice, this list of conditions and the following disclaimer in
  39 *     the documentation and/or other materials provided with the
  40 *     distribution.
  41 *   * Neither the name of Intel Corporation nor the names of its
  42 *     contributors may be used to endorse or promote products derived
  43 *     from this software without specific prior written permission.
  44 *
  45 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  46 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  47 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  48 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  49 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  50 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  51 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  52 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  53 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  54 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  55 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  56 */
  57#include <linux/err.h>
  58#include <linux/init.h>
  59#include <linux/io.h>
  60#include <linux/of.h>
  61#include <linux/platform_device.h>
  62#include <linux/reset-controller.h>
  63#include <linux/slab.h>
  64#include <linux/types.h>
  65#include <linux/of_device.h>
  66
  67#define REG_COUNT       8
  68#define BITS_PER_REG    32
  69#define LEVEL_OFFSET    0x7c
  70
  71struct meson_reset {
  72        void __iomem *reg_base;
  73        struct reset_controller_dev rcdev;
  74        spinlock_t lock;
  75};
  76
  77static int meson_reset_reset(struct reset_controller_dev *rcdev,
  78                              unsigned long id)
  79{
  80        struct meson_reset *data =
  81                container_of(rcdev, struct meson_reset, rcdev);
  82        unsigned int bank = id / BITS_PER_REG;
  83        unsigned int offset = id % BITS_PER_REG;
  84        void __iomem *reg_addr = data->reg_base + (bank << 2);
  85
  86        writel(BIT(offset), reg_addr);
  87
  88        return 0;
  89}
  90
  91static int meson_reset_level(struct reset_controller_dev *rcdev,
  92                            unsigned long id, bool assert)
  93{
  94        struct meson_reset *data =
  95                container_of(rcdev, struct meson_reset, rcdev);
  96        unsigned int bank = id / BITS_PER_REG;
  97        unsigned int offset = id % BITS_PER_REG;
  98        void __iomem *reg_addr = data->reg_base + LEVEL_OFFSET + (bank << 2);
  99        unsigned long flags;
 100        u32 reg;
 101
 102        spin_lock_irqsave(&data->lock, flags);
 103
 104        reg = readl(reg_addr);
 105        if (assert)
 106                writel(reg & ~BIT(offset), reg_addr);
 107        else
 108                writel(reg | BIT(offset), reg_addr);
 109
 110        spin_unlock_irqrestore(&data->lock, flags);
 111
 112        return 0;
 113}
 114
 115static int meson_reset_assert(struct reset_controller_dev *rcdev,
 116                              unsigned long id)
 117{
 118        return meson_reset_level(rcdev, id, true);
 119}
 120
 121static int meson_reset_deassert(struct reset_controller_dev *rcdev,
 122                                unsigned long id)
 123{
 124        return meson_reset_level(rcdev, id, false);
 125}
 126
 127static const struct reset_control_ops meson_reset_ops = {
 128        .reset          = meson_reset_reset,
 129        .assert         = meson_reset_assert,
 130        .deassert       = meson_reset_deassert,
 131};
 132
 133static const struct of_device_id meson_reset_dt_ids[] = {
 134         { .compatible = "amlogic,meson8b-reset" },
 135         { .compatible = "amlogic,meson-gxbb-reset" },
 136         { .compatible = "amlogic,meson-axg-reset" },
 137         { /* sentinel */ },
 138};
 139
 140static int meson_reset_probe(struct platform_device *pdev)
 141{
 142        struct meson_reset *data;
 143        struct resource *res;
 144
 145        data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 146        if (!data)
 147                return -ENOMEM;
 148
 149        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 150        data->reg_base = devm_ioremap_resource(&pdev->dev, res);
 151        if (IS_ERR(data->reg_base))
 152                return PTR_ERR(data->reg_base);
 153
 154        platform_set_drvdata(pdev, data);
 155
 156        spin_lock_init(&data->lock);
 157
 158        data->rcdev.owner = THIS_MODULE;
 159        data->rcdev.nr_resets = REG_COUNT * BITS_PER_REG;
 160        data->rcdev.ops = &meson_reset_ops;
 161        data->rcdev.of_node = pdev->dev.of_node;
 162
 163        return devm_reset_controller_register(&pdev->dev, &data->rcdev);
 164}
 165
 166static struct platform_driver meson_reset_driver = {
 167        .probe  = meson_reset_probe,
 168        .driver = {
 169                .name           = "meson_reset",
 170                .of_match_table = meson_reset_dt_ids,
 171        },
 172};
 173builtin_platform_driver(meson_reset_driver);
 174