// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) STMicroelectronics 2022 - All Rights Reserved
 * Author: Gabriel Fernandez <gabriel.fernandez@foss.st.com> for STMicroelectronics.
 */

#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/reset-controller.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

#include "reset-stm32.h"

struct stm32_reset_data {
        /* reset lock */
        spinlock_t                      lock;
        struct reset_controller_dev     rcdev;
        void __iomem                    *membase;
        u32                             clear_offset;
        const struct stm32_reset_cfg    **reset_lines;
};

static inline struct stm32_reset_data *
to_stm32_reset_data(struct reset_controller_dev *rcdev)
{
        return container_of(rcdev, struct stm32_reset_data, rcdev);
}

static const struct stm32_reset_cfg *stm32_get_reset_line(struct reset_controller_dev *rcdev,
                                                          unsigned long id,
                                                          struct stm32_reset_cfg *line)
{
        struct stm32_reset_data *data = to_stm32_reset_data(rcdev);

        if (!data->reset_lines) {
                int reg_width = sizeof(u32);
                int bank = id / (reg_width * BITS_PER_BYTE);
                int offset = id % (reg_width * BITS_PER_BYTE);

                line->offset = bank * reg_width;
                line->bit_idx = offset;
                line->set_clr = (data->clear_offset ? true : false);

                return line;
        }

        return data->reset_lines[id];
}

static int stm32_reset_update(struct reset_controller_dev *rcdev,
                              unsigned long id, bool assert)
{
        struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
        struct stm32_reset_cfg line_reset;
        const struct stm32_reset_cfg *ptr_line;

        ptr_line = stm32_get_reset_line(rcdev, id, &line_reset);
        if (!ptr_line)
                return -EPERM;

        if (ptr_line->set_clr) {
                void __iomem *addr;

                addr = data->membase + ptr_line->offset;
                if (!assert)
                        addr += data->clear_offset;

                writel(BIT(ptr_line->bit_idx), addr);

        } else {
                unsigned long flags;
                u32 reg;

                spin_lock_irqsave(&data->lock, flags);

                reg = readl(data->membase + ptr_line->offset);

                if (assert)
                        reg |= BIT(ptr_line->bit_idx);
                else
                        reg &= ~BIT(ptr_line->bit_idx);

                writel(reg, data->membase + ptr_line->offset);

                spin_unlock_irqrestore(&data->lock, flags);
        }

        return 0;
}

static int stm32_reset_assert(struct reset_controller_dev *rcdev,
                              unsigned long id)
{
        return stm32_reset_update(rcdev, id, true);
}

static int stm32_reset_deassert(struct reset_controller_dev *rcdev,
                                unsigned long id)
{
        return stm32_reset_update(rcdev, id, false);
}

static int stm32_reset_status(struct reset_controller_dev *rcdev,
                              unsigned long id)
{
        struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
        struct stm32_reset_cfg line_reset;
        const struct stm32_reset_cfg *ptr_line;
        u32 reg;

        ptr_line = stm32_get_reset_line(rcdev, id, &line_reset);
        if (!ptr_line)
                return -EPERM;

        reg = readl(data->membase + ptr_line->offset);

        return !!(reg & BIT(ptr_line->bit_idx));
}

static const struct reset_control_ops stm32_reset_ops = {
        .assert         = stm32_reset_assert,
        .deassert       = stm32_reset_deassert,
        .status         = stm32_reset_status,
};

int stm32_rcc_reset_init(struct device *dev, struct clk_stm32_reset_data *data,
                         void __iomem *base)
{
        struct stm32_reset_data *reset_data;

        reset_data = kzalloc_obj(*reset_data);
        if (!reset_data)
                return -ENOMEM;

        spin_lock_init(&reset_data->lock);

        reset_data->membase = base;
        reset_data->rcdev.owner = THIS_MODULE;
        reset_data->rcdev.ops = &stm32_reset_ops;
        reset_data->rcdev.of_node = dev_of_node(dev);
        reset_data->rcdev.nr_resets = data->nr_lines;
        reset_data->reset_lines = data->reset_lines;
        reset_data->clear_offset = data->clear_offset;

        return reset_controller_register(&reset_data->rcdev);
}