// SPDX-License-Identifier: GPL-2.0
/*
 * BCM63268 Timer Clock and Reset Controller Driver
 *
 * Copyright (C) 2023 Álvaro Fernández Rojas <noltari@gmail.com>
 */

#include <linux/clk-provider.h>
#include <linux/container_of.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/reset-controller.h>
#include <linux/spinlock.h>

#include <dt-bindings/clock/bcm63268-clock.h>

#define BCM63268_TIMER_RESET_SLEEP_MIN_US	10000
#define BCM63268_TIMER_RESET_SLEEP_MAX_US	20000

struct bcm63268_tclkrst_hw {
	void __iomem *regs;
	spinlock_t lock;

	struct reset_controller_dev rcdev;
	struct clk_hw_onecell_data data;
};

struct bcm63268_tclk_table_entry {
	const char * const name;
	u8 bit;
};

static const struct bcm63268_tclk_table_entry bcm63268_timer_clocks[] = {
	{
		.name = "ephy1",
		.bit = BCM63268_TCLK_EPHY1,
	}, {
		.name = "ephy2",
		.bit = BCM63268_TCLK_EPHY2,
	}, {
		.name = "ephy3",
		.bit = BCM63268_TCLK_EPHY3,
	}, {
		.name = "gphy1",
		.bit = BCM63268_TCLK_GPHY1,
	}, {
		.name = "dsl",
		.bit = BCM63268_TCLK_DSL,
	}, {
		.name = "wakeon_ephy",
		.bit = BCM63268_TCLK_WAKEON_EPHY,
	}, {
		.name = "wakeon_dsl",
		.bit = BCM63268_TCLK_WAKEON_DSL,
	}, {
		.name = "fap1_pll",
		.bit = BCM63268_TCLK_FAP1,
	}, {
		.name = "fap2_pll",
		.bit = BCM63268_TCLK_FAP2,
	}, {
		.name = "uto_50",
		.bit = BCM63268_TCLK_UTO_50,
	}, {
		.name = "uto_extin",
		.bit = BCM63268_TCLK_UTO_EXTIN,
	}, {
		.name = "usb_ref",
		.bit = BCM63268_TCLK_USB_REF,
	}, {
		/* sentinel */
	}
};

static inline struct bcm63268_tclkrst_hw *
to_bcm63268_timer_reset(struct reset_controller_dev *rcdev)
{
	return container_of(rcdev, struct bcm63268_tclkrst_hw, rcdev);
}

static int bcm63268_timer_reset_update(struct reset_controller_dev *rcdev,
				unsigned long id, bool assert)
{
	struct bcm63268_tclkrst_hw *reset = to_bcm63268_timer_reset(rcdev);
	unsigned long flags;
	uint32_t val;

	spin_lock_irqsave(&reset->lock, flags);
	val = __raw_readl(reset->regs);
	if (assert)
		val &= ~BIT(id);
	else
		val |= BIT(id);
	__raw_writel(val, reset->regs);
	spin_unlock_irqrestore(&reset->lock, flags);

	return 0;
}

static int bcm63268_timer_reset_assert(struct reset_controller_dev *rcdev,
				unsigned long id)
{
	return bcm63268_timer_reset_update(rcdev, id, true);
}

static int bcm63268_timer_reset_deassert(struct reset_controller_dev *rcdev,
				  unsigned long id)
{
	return bcm63268_timer_reset_update(rcdev, id, false);
}

static int bcm63268_timer_reset_reset(struct reset_controller_dev *rcdev,
			       unsigned long id)
{
	bcm63268_timer_reset_update(rcdev, id, true);
	usleep_range(BCM63268_TIMER_RESET_SLEEP_MIN_US,
		     BCM63268_TIMER_RESET_SLEEP_MAX_US);

	bcm63268_timer_reset_update(rcdev, id, false);
	/*
	 * Ensure component is taken out reset state by sleeping also after
	 * deasserting the reset. Otherwise, the component may not be ready
	 * for operation.
	 */
	usleep_range(BCM63268_TIMER_RESET_SLEEP_MIN_US,
		     BCM63268_TIMER_RESET_SLEEP_MAX_US);

	return 0;
}

static int bcm63268_timer_reset_status(struct reset_controller_dev *rcdev,
				unsigned long id)
{
	struct bcm63268_tclkrst_hw *reset = to_bcm63268_timer_reset(rcdev);

	return !(__raw_readl(reset->regs) & BIT(id));
}

static const struct reset_control_ops bcm63268_timer_reset_ops = {
	.assert = bcm63268_timer_reset_assert,
	.deassert = bcm63268_timer_reset_deassert,
	.reset = bcm63268_timer_reset_reset,
	.status = bcm63268_timer_reset_status,
};

static int bcm63268_tclk_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	const struct bcm63268_tclk_table_entry *entry;
	struct bcm63268_tclkrst_hw *hw;
	struct clk_hw *clk;
	u8 maxbit = 0;
	int i, ret;

	for (entry = bcm63268_timer_clocks; entry->name; entry++)
		maxbit = max(maxbit, entry->bit);
	maxbit++;

	hw = devm_kzalloc(&pdev->dev, struct_size(hw, data.hws, maxbit),
			  GFP_KERNEL);
	if (!hw)
		return -ENOMEM;

	platform_set_drvdata(pdev, hw);

	spin_lock_init(&hw->lock);

	hw->data.num = maxbit;
	for (i = 0; i < maxbit; i++)
		hw->data.hws[i] = ERR_PTR(-ENODEV);

	hw->regs = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(hw->regs))
		return PTR_ERR(hw->regs);

	for (entry = bcm63268_timer_clocks; entry->name; entry++) {
		clk = devm_clk_hw_register_gate(dev, entry->name, NULL, 0,
						hw->regs, entry->bit,
						CLK_GATE_BIG_ENDIAN,
						&hw->lock);
		if (IS_ERR(clk))
			return PTR_ERR(clk);

		hw->data.hws[entry->bit] = clk;
	}

	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
					  &hw->data);
	if (ret)
		return ret;

	hw->rcdev.of_node = dev->of_node;
	hw->rcdev.ops = &bcm63268_timer_reset_ops;

	ret = devm_reset_controller_register(dev, &hw->rcdev);
	if (ret)
		dev_err(dev, "Failed to register reset controller\n");

	return 0;
}

static const struct of_device_id bcm63268_tclk_dt_ids[] = {
	{ .compatible = "brcm,bcm63268-timer-clocks" },
	{ /* sentinel */ }
};

static struct platform_driver bcm63268_tclk = {
	.probe = bcm63268_tclk_probe,
	.driver = {
		.name = "bcm63268-timer-clock",
		.of_match_table = bcm63268_tclk_dt_ids,
	},
};
builtin_platform_driver(bcm63268_tclk);