// SPDX-License-Identifier: GPL-2.0-only
// Copyright (c) 2021 Sunplus Inc.
// Author: Li-hao Kuo <lhjeff911@gmail.com>

#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>
#include <linux/spi/spi.h>

#define SP7021_DATA_RDY_REG		0x0044
#define SP7021_SLAVE_DMA_CTRL_REG	0x0048
#define SP7021_SLAVE_DMA_LENGTH_REG	0x004c
#define SP7021_SLAVE_DMA_ADDR_REG	0x004c

#define SP7021_SLAVE_DATA_RDY		BIT(0)
#define SP7021_SLAVE_SW_RST		BIT(1)
#define SP7021_SLA_DMA_W_INT		BIT(8)
#define SP7021_SLAVE_CLR_INT		BIT(8)
#define SP7021_SLAVE_DMA_EN		BIT(0)
#define SP7021_SLAVE_DMA_RW		BIT(6)
#define SP7021_SLAVE_DMA_CMD		GENMASK(3, 2)

#define SP7021_FIFO_REG			0x0034
#define SP7021_SPI_STATUS_REG		0x0038
#define SP7021_SPI_CONFIG_REG		0x003c
#define SP7021_INT_BUSY_REG		0x004c
#define SP7021_DMA_CTRL_REG		0x0050

#define SP7021_SPI_START_FD		BIT(0)
#define SP7021_FD_SW_RST		BIT(1)
#define SP7021_TX_EMP_FLAG		BIT(2)
#define SP7021_RX_EMP_FLAG		BIT(4)
#define SP7021_RX_FULL_FLAG		BIT(5)
#define SP7021_FINISH_FLAG		BIT(6)

#define SP7021_TX_CNT_MASK		GENMASK(11, 8)
#define SP7021_RX_CNT_MASK		GENMASK(15, 12)
#define SP7021_TX_LEN_MASK		GENMASK(23, 16)
#define SP7021_GET_LEN_MASK		GENMASK(31, 24)
#define SP7021_SET_TX_LEN		GENMASK(23, 16)
#define SP7021_SET_XFER_LEN		GENMASK(31, 24)

#define SP7021_CPOL_FD			BIT(0)
#define SP7021_CPHA_R			BIT(1)
#define SP7021_CPHA_W			BIT(2)
#define SP7021_LSB_SEL			BIT(4)
#define SP7021_CS_POR			BIT(5)
#define SP7021_FD_SEL			BIT(6)

#define SP7021_RX_UNIT			GENMASK(8, 7)
#define SP7021_TX_UNIT			GENMASK(10, 9)
#define SP7021_TX_EMP_FLAG_MASK		BIT(11)
#define SP7021_RX_FULL_FLAG_MASK	BIT(14)
#define SP7021_FINISH_FLAG_MASK		BIT(15)
#define SP7021_CLEAN_RW_BYTE		GENMASK(10, 7)
#define SP7021_CLEAN_FLUG_MASK		GENMASK(15, 11)
#define SP7021_CLK_MASK			GENMASK(31, 16)

#define SP7021_INT_BYPASS		BIT(3)
#define SP7021_CLR_MASTER_INT		BIT(6)

#define SP7021_SPI_DATA_SIZE		(255)
#define SP7021_FIFO_DATA_LEN		(16)

enum {
	SP7021_HOST_MODE = 0,
	SP7021_TARGET_MODE = 1,
};

struct sp7021_spi_ctlr {
	struct device *dev;
	struct spi_controller *ctlr;
	void __iomem *m_base;
	void __iomem *s_base;
	u32 xfer_conf;
	int mode;
	int m_irq;
	int s_irq;
	struct clk *spi_clk;
	struct reset_control *rstc;
	// data xfer lock
	struct mutex buf_lock;
	struct completion isr_done;
	struct completion target_isr;
	unsigned int  rx_cur_len;
	unsigned int  tx_cur_len;
	unsigned int  data_unit;
	const u8 *tx_buf;
	u8 *rx_buf;
};

static irqreturn_t sp7021_spi_target_irq(int irq, void *dev)
{
	struct sp7021_spi_ctlr *pspim = dev;
	unsigned int data_status;

	data_status = readl(pspim->s_base + SP7021_DATA_RDY_REG);
	data_status |= SP7021_SLAVE_CLR_INT;
	writel(data_status, pspim->s_base + SP7021_DATA_RDY_REG);
	complete(&pspim->target_isr);
	return IRQ_HANDLED;
}

static int sp7021_spi_target_abort(struct spi_controller *ctlr)
{
	struct sp7021_spi_ctlr *pspim = spi_controller_get_devdata(ctlr);

	complete(&pspim->target_isr);
	complete(&pspim->isr_done);
	return 0;
}

static int sp7021_spi_target_tx(struct spi_device *spi, struct spi_transfer *xfer)
{
	struct sp7021_spi_ctlr *pspim = spi_controller_get_devdata(spi->controller);
	u32 value;

	reinit_completion(&pspim->target_isr);
	value = SP7021_SLAVE_DMA_EN | SP7021_SLAVE_DMA_RW | FIELD_PREP(SP7021_SLAVE_DMA_CMD, 3);
	writel(value, pspim->s_base + SP7021_SLAVE_DMA_CTRL_REG);
	writel(xfer->len, pspim->s_base + SP7021_SLAVE_DMA_LENGTH_REG);
	writel(xfer->tx_dma, pspim->s_base + SP7021_SLAVE_DMA_ADDR_REG);
	value = readl(pspim->s_base + SP7021_DATA_RDY_REG);
	value |= SP7021_SLAVE_DATA_RDY;
	writel(value, pspim->s_base + SP7021_DATA_RDY_REG);
	if (wait_for_completion_interruptible(&pspim->isr_done)) {
		dev_err(&spi->dev, "%s() wait_for_completion err\n", __func__);
		return -EINTR;
	}
	return 0;
}

static int sp7021_spi_target_rx(struct spi_device *spi, struct spi_transfer *xfer)
{
	struct sp7021_spi_ctlr *pspim = spi_controller_get_devdata(spi->controller);
	u32 value;

	reinit_completion(&pspim->isr_done);
	value = SP7021_SLAVE_DMA_EN | FIELD_PREP(SP7021_SLAVE_DMA_CMD, 3);
	writel(value, pspim->s_base + SP7021_SLAVE_DMA_CTRL_REG);
	writel(xfer->len, pspim->s_base + SP7021_SLAVE_DMA_LENGTH_REG);
	writel(xfer->rx_dma, pspim->s_base + SP7021_SLAVE_DMA_ADDR_REG);
	if (wait_for_completion_interruptible(&pspim->isr_done)) {
		dev_err(&spi->dev, "%s() wait_for_completion err\n", __func__);
		return -EINTR;
	}
	writel(SP7021_SLAVE_SW_RST, pspim->s_base + SP7021_SLAVE_DMA_CTRL_REG);
	return 0;
}

static void sp7021_spi_host_rb(struct sp7021_spi_ctlr *pspim, unsigned int len)
{
	int i;

	for (i = 0; i < len; i++) {
		pspim->rx_buf[pspim->rx_cur_len] =
			readl(pspim->m_base + SP7021_FIFO_REG);
		pspim->rx_cur_len++;
	}
}

static void sp7021_spi_host_wb(struct sp7021_spi_ctlr *pspim, unsigned int len)
{
	int i;

	for (i = 0; i < len; i++) {
		writel(pspim->tx_buf[pspim->tx_cur_len],
		       pspim->m_base + SP7021_FIFO_REG);
		pspim->tx_cur_len++;
	}
}

static irqreturn_t sp7021_spi_host_irq(int irq, void *dev)
{
	struct sp7021_spi_ctlr *pspim = dev;
	unsigned int tx_cnt, total_len;
	unsigned int tx_len, rx_cnt;
	unsigned int fd_status;
	bool isrdone = false;
	u32 value;

	fd_status = readl(pspim->m_base + SP7021_SPI_STATUS_REG);
	tx_cnt = FIELD_GET(SP7021_TX_CNT_MASK, fd_status);
	tx_len = FIELD_GET(SP7021_TX_LEN_MASK, fd_status);
	total_len = FIELD_GET(SP7021_GET_LEN_MASK, fd_status);

	if ((fd_status & SP7021_TX_EMP_FLAG) && (fd_status & SP7021_RX_EMP_FLAG) && total_len == 0)
		return IRQ_NONE;

	if (tx_len == 0 && total_len == 0)
		return IRQ_NONE;

	rx_cnt = FIELD_GET(SP7021_RX_CNT_MASK, fd_status);
	if (fd_status & SP7021_RX_FULL_FLAG)
		rx_cnt = pspim->data_unit;

	tx_cnt = min(tx_len - pspim->tx_cur_len, pspim->data_unit - tx_cnt);
	dev_dbg(pspim->dev, "fd_st=0x%x rx_c:%d tx_c:%d tx_l:%d",
		fd_status, rx_cnt, tx_cnt, tx_len);

	if (rx_cnt > 0)
		sp7021_spi_host_rb(pspim, rx_cnt);
	if (tx_cnt > 0)
		sp7021_spi_host_wb(pspim, tx_cnt);

	fd_status = readl(pspim->m_base + SP7021_SPI_STATUS_REG);
	tx_len = FIELD_GET(SP7021_TX_LEN_MASK, fd_status);
	total_len = FIELD_GET(SP7021_GET_LEN_MASK, fd_status);

	if (fd_status & SP7021_FINISH_FLAG || tx_len == pspim->tx_cur_len) {
		while (total_len != pspim->rx_cur_len) {
			fd_status = readl(pspim->m_base + SP7021_SPI_STATUS_REG);
			total_len = FIELD_GET(SP7021_GET_LEN_MASK, fd_status);
			if (fd_status & SP7021_RX_FULL_FLAG)
				rx_cnt = pspim->data_unit;
			else
				rx_cnt = FIELD_GET(SP7021_RX_CNT_MASK, fd_status);

			if (rx_cnt > 0)
				sp7021_spi_host_rb(pspim, rx_cnt);
		}
		value = readl(pspim->m_base + SP7021_INT_BUSY_REG);
		value |= SP7021_CLR_MASTER_INT;
		writel(value, pspim->m_base + SP7021_INT_BUSY_REG);
		writel(SP7021_FINISH_FLAG, pspim->m_base + SP7021_SPI_STATUS_REG);
		isrdone = true;
	}

	if (isrdone)
		complete(&pspim->isr_done);
	return IRQ_HANDLED;
}

static void sp7021_prep_transfer(struct spi_controller *ctlr, struct spi_device *spi)
{
	struct sp7021_spi_ctlr *pspim = spi_controller_get_devdata(ctlr);

	pspim->tx_cur_len = 0;
	pspim->rx_cur_len = 0;
	pspim->data_unit = SP7021_FIFO_DATA_LEN;
}

// preliminary set CS, CPOL, CPHA and LSB
static int sp7021_spi_controller_prepare_message(struct spi_controller *ctlr,
						 struct spi_message *msg)
{
	struct sp7021_spi_ctlr *pspim = spi_controller_get_devdata(ctlr);
	struct spi_device *s = msg->spi;
	u32 valus, rs = 0;

	valus = readl(pspim->m_base + SP7021_SPI_STATUS_REG);
	valus |= SP7021_FD_SW_RST;
	writel(valus, pspim->m_base + SP7021_SPI_STATUS_REG);
	rs |= SP7021_FD_SEL;
	if (s->mode & SPI_CPOL)
		rs |= SP7021_CPOL_FD;

	if (s->mode & SPI_LSB_FIRST)
		rs |= SP7021_LSB_SEL;

	if (s->mode & SPI_CS_HIGH)
		rs |= SP7021_CS_POR;

	if (s->mode & SPI_CPHA)
		rs |=  SP7021_CPHA_R;
	else
		rs |=  SP7021_CPHA_W;

	rs |=  FIELD_PREP(SP7021_TX_UNIT, 0) | FIELD_PREP(SP7021_RX_UNIT, 0);
	pspim->xfer_conf = rs;
	if (pspim->xfer_conf & SP7021_CPOL_FD)
		writel(pspim->xfer_conf, pspim->m_base + SP7021_SPI_CONFIG_REG);

	return 0;
}

static void sp7021_spi_setup_clk(struct spi_controller *ctlr, struct spi_transfer *xfer)
{
	struct sp7021_spi_ctlr *pspim = spi_controller_get_devdata(ctlr);
	u32 clk_rate, clk_sel, div;

	clk_rate = clk_get_rate(pspim->spi_clk);
	div = max(2U, clk_rate / xfer->speed_hz);

	clk_sel = (div / 2) - 1;
	FIELD_MODIFY(SP7021_CLK_MASK, &pspim->xfer_conf, clk_sel);
	writel(pspim->xfer_conf, pspim->m_base + SP7021_SPI_CONFIG_REG);
}

static int sp7021_spi_host_transfer_one(struct spi_controller *ctlr, struct spi_device *spi,
					struct spi_transfer *xfer)
{
	struct sp7021_spi_ctlr *pspim = spi_controller_get_devdata(ctlr);
	unsigned long timeout = msecs_to_jiffies(1000);
	unsigned int xfer_cnt, xfer_len, last_len;
	unsigned int i, len_temp;
	u32 reg_temp;

	xfer_cnt = xfer->len / SP7021_SPI_DATA_SIZE;
	last_len = xfer->len % SP7021_SPI_DATA_SIZE;

	for (i = 0; i <= xfer_cnt; i++) {
		mutex_lock(&pspim->buf_lock);
		sp7021_prep_transfer(ctlr, spi);
		sp7021_spi_setup_clk(ctlr, xfer);
		reinit_completion(&pspim->isr_done);

		if (i == xfer_cnt)
			xfer_len = last_len;
		else
			xfer_len = SP7021_SPI_DATA_SIZE;

		pspim->tx_buf = xfer->tx_buf + i * SP7021_SPI_DATA_SIZE;
		pspim->rx_buf = xfer->rx_buf + i * SP7021_SPI_DATA_SIZE;

		if (pspim->tx_cur_len < xfer_len) {
			len_temp = min(pspim->data_unit, xfer_len);
			sp7021_spi_host_wb(pspim, len_temp);
		}
		reg_temp = readl(pspim->m_base + SP7021_SPI_CONFIG_REG);
		reg_temp &= ~SP7021_CLEAN_RW_BYTE;
		reg_temp &= ~SP7021_CLEAN_FLUG_MASK;
		reg_temp |= SP7021_FD_SEL | SP7021_FINISH_FLAG_MASK |
			    SP7021_TX_EMP_FLAG_MASK | SP7021_RX_FULL_FLAG_MASK |
			    FIELD_PREP(SP7021_TX_UNIT, 0) | FIELD_PREP(SP7021_RX_UNIT, 0);
		writel(reg_temp, pspim->m_base + SP7021_SPI_CONFIG_REG);

		reg_temp = FIELD_PREP(SP7021_SET_TX_LEN, xfer_len) |
				      FIELD_PREP(SP7021_SET_XFER_LEN, xfer_len) |
				      SP7021_SPI_START_FD;
		writel(reg_temp, pspim->m_base + SP7021_SPI_STATUS_REG);

		if (!wait_for_completion_interruptible_timeout(&pspim->isr_done, timeout)) {
			dev_err(&spi->dev, "wait_for_completion err\n");
			mutex_unlock(&pspim->buf_lock);
			return -ETIMEDOUT;
		}

		reg_temp = readl(pspim->m_base + SP7021_SPI_STATUS_REG);
		if (reg_temp & SP7021_FINISH_FLAG) {
			writel(SP7021_FINISH_FLAG, pspim->m_base + SP7021_SPI_STATUS_REG);
			writel(readl(pspim->m_base + SP7021_SPI_CONFIG_REG) &
				SP7021_CLEAN_FLUG_MASK, pspim->m_base + SP7021_SPI_CONFIG_REG);
		}

		if (pspim->xfer_conf & SP7021_CPOL_FD)
			writel(pspim->xfer_conf, pspim->m_base + SP7021_SPI_CONFIG_REG);

		mutex_unlock(&pspim->buf_lock);
	}
	return 0;
}

static int sp7021_spi_target_transfer_one(struct spi_controller *ctlr, struct spi_device *spi,
					  struct spi_transfer *xfer)
{
	struct sp7021_spi_ctlr *pspim = spi_controller_get_devdata(ctlr);
	struct device *dev = pspim->dev;
	int ret;

	if (xfer->tx_buf && !xfer->rx_buf) {
		xfer->tx_dma = dma_map_single(dev, (void *)xfer->tx_buf,
					      xfer->len, DMA_TO_DEVICE);
		if (dma_mapping_error(dev, xfer->tx_dma))
			return -ENOMEM;
		ret = sp7021_spi_target_tx(spi, xfer);
		dma_unmap_single(dev, xfer->tx_dma, xfer->len, DMA_TO_DEVICE);
	} else if (xfer->rx_buf && !xfer->tx_buf) {
		xfer->rx_dma = dma_map_single(dev, xfer->rx_buf, xfer->len,
					      DMA_FROM_DEVICE);
		if (dma_mapping_error(dev, xfer->rx_dma))
			return -ENOMEM;
		ret = sp7021_spi_target_rx(spi, xfer);
		dma_unmap_single(dev, xfer->rx_dma, xfer->len, DMA_FROM_DEVICE);
	} else {
		dev_dbg(&ctlr->dev, "%s() wrong command\n", __func__);
		return -EINVAL;
	}

	spi_finalize_current_transfer(ctlr);
	return ret;
}

static void sp7021_spi_reset_control_assert(void *data)
{
	reset_control_assert(data);
}

static int sp7021_spi_controller_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct sp7021_spi_ctlr *pspim;
	struct spi_controller *ctlr;
	int mode, ret;

	pdev->id = of_alias_get_id(pdev->dev.of_node, "sp_spi");

	if (device_property_read_bool(dev, "spi-slave"))
		mode = SP7021_TARGET_MODE;
	else
		mode = SP7021_HOST_MODE;

	if (mode == SP7021_TARGET_MODE)
		ctlr = devm_spi_alloc_target(dev, sizeof(*pspim));
	else
		ctlr = devm_spi_alloc_host(dev, sizeof(*pspim));
	if (!ctlr)
		return -ENOMEM;
	ctlr->bus_num = pdev->id;
	ctlr->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST;
	ctlr->auto_runtime_pm = true;
	ctlr->prepare_message = sp7021_spi_controller_prepare_message;
	if (mode == SP7021_TARGET_MODE) {
		ctlr->transfer_one = sp7021_spi_target_transfer_one;
		ctlr->target_abort = sp7021_spi_target_abort;
		ctlr->flags = SPI_CONTROLLER_HALF_DUPLEX;
	} else {
		ctlr->bits_per_word_mask = SPI_BPW_MASK(8);
		ctlr->min_speed_hz = 40000;
		ctlr->max_speed_hz = 25000000;
		ctlr->use_gpio_descriptors = true;
		ctlr->flags = SPI_CONTROLLER_MUST_RX | SPI_CONTROLLER_MUST_TX;
		ctlr->transfer_one = sp7021_spi_host_transfer_one;
	}
	platform_set_drvdata(pdev, ctlr);
	pspim = spi_controller_get_devdata(ctlr);
	pspim->mode = mode;
	pspim->ctlr = ctlr;
	pspim->dev = dev;
	mutex_init(&pspim->buf_lock);
	init_completion(&pspim->isr_done);
	init_completion(&pspim->target_isr);

	pspim->m_base = devm_platform_ioremap_resource_byname(pdev, "master");
	if (IS_ERR(pspim->m_base))
		return dev_err_probe(dev, PTR_ERR(pspim->m_base), "m_base get fail\n");

	pspim->s_base = devm_platform_ioremap_resource_byname(pdev, "slave");
	if (IS_ERR(pspim->s_base))
		return dev_err_probe(dev, PTR_ERR(pspim->s_base), "s_base get fail\n");

	pspim->m_irq = platform_get_irq_byname(pdev, "master_risc");
	if (pspim->m_irq < 0)
		return pspim->m_irq;

	pspim->s_irq = platform_get_irq_byname(pdev, "slave_risc");
	if (pspim->s_irq < 0)
		return pspim->s_irq;

	pspim->spi_clk = devm_clk_get_enabled(dev, NULL);
	if (IS_ERR(pspim->spi_clk))
		return dev_err_probe(dev, PTR_ERR(pspim->spi_clk), "clk get fail\n");

	pspim->rstc = devm_reset_control_get_exclusive(dev, NULL);
	if (IS_ERR(pspim->rstc))
		return dev_err_probe(dev, PTR_ERR(pspim->rstc), "rst get fail\n");

	ret = reset_control_deassert(pspim->rstc);
	if (ret)
		return dev_err_probe(dev, ret, "failed to deassert reset\n");

	ret = devm_add_action_or_reset(dev, sp7021_spi_reset_control_assert, pspim->rstc);
	if (ret)
		return ret;

	ret = devm_request_irq(dev, pspim->m_irq, sp7021_spi_host_irq,
			       IRQF_TRIGGER_RISING, pdev->name, pspim);
	if (ret)
		return ret;

	ret = devm_request_irq(dev, pspim->s_irq, sp7021_spi_target_irq,
			       IRQF_TRIGGER_RISING, pdev->name, pspim);
	if (ret)
		return ret;

	pm_runtime_enable(dev);
	ret = spi_register_controller(ctlr);
	if (ret) {
		pm_runtime_disable(dev);
		return dev_err_probe(dev, ret, "spi_register_controller fail\n");
	}
	return 0;
}

static void sp7021_spi_controller_remove(struct platform_device *pdev)
{
	struct spi_controller *ctlr = dev_get_drvdata(&pdev->dev);

	spi_unregister_controller(ctlr);
	pm_runtime_disable(&pdev->dev);
	pm_runtime_set_suspended(&pdev->dev);
}

static int __maybe_unused sp7021_spi_controller_suspend(struct device *dev)
{
	struct spi_controller *ctlr = dev_get_drvdata(dev);
	struct sp7021_spi_ctlr *pspim = spi_controller_get_devdata(ctlr);

	return reset_control_assert(pspim->rstc);
}

static int __maybe_unused sp7021_spi_controller_resume(struct device *dev)
{
	struct spi_controller *ctlr = dev_get_drvdata(dev);
	struct sp7021_spi_ctlr *pspim = spi_controller_get_devdata(ctlr);

	reset_control_deassert(pspim->rstc);
	return clk_prepare_enable(pspim->spi_clk);
}

#ifdef CONFIG_PM
static int sp7021_spi_runtime_suspend(struct device *dev)
{
	struct spi_controller *ctlr = dev_get_drvdata(dev);
	struct sp7021_spi_ctlr *pspim = spi_controller_get_devdata(ctlr);

	return reset_control_assert(pspim->rstc);
}

static int sp7021_spi_runtime_resume(struct device *dev)
{
	struct spi_controller *ctlr = dev_get_drvdata(dev);
	struct sp7021_spi_ctlr *pspim = spi_controller_get_devdata(ctlr);

	return reset_control_deassert(pspim->rstc);
}
#endif

static const struct dev_pm_ops sp7021_spi_pm_ops = {
	SET_RUNTIME_PM_OPS(sp7021_spi_runtime_suspend,
			   sp7021_spi_runtime_resume, NULL)
	SET_SYSTEM_SLEEP_PM_OPS(sp7021_spi_controller_suspend,
				sp7021_spi_controller_resume)
};

static const struct of_device_id sp7021_spi_controller_ids[] = {
	{ .compatible = "sunplus,sp7021-spi" },
	{}
};
MODULE_DEVICE_TABLE(of, sp7021_spi_controller_ids);

static struct platform_driver sp7021_spi_controller_driver = {
	.probe = sp7021_spi_controller_probe,
	.remove = sp7021_spi_controller_remove,
	.driver = {
		.name = "sunplus,sp7021-spi-controller",
		.of_match_table = sp7021_spi_controller_ids,
		.pm     = &sp7021_spi_pm_ops,
	},
};
module_platform_driver(sp7021_spi_controller_driver);

MODULE_AUTHOR("Li-hao Kuo <lhjeff911@gmail.com>");
MODULE_DESCRIPTION("Sunplus SPI controller driver");
MODULE_LICENSE("GPL");