/*
 * TI QSPI driver
 *
 * Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com
 * Author: Sourav Poddar <sourav.poddar@ti.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GPLv2.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR /PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/omap-dma.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/pinctrl/consumer.h>

#include <linux/spi/spi.h>

struct ti_qspi_regs {
	u32 clkctrl;
};

struct ti_qspi {
	struct completion       transfer_complete;

	/* IRQ synchronization */
	spinlock_t              lock;

	/* list synchronization */
	struct mutex            list_lock;

	struct spi_master	*master;
	void __iomem            *base;
	struct clk		*fclk;
	struct device           *dev;

	struct ti_qspi_regs     ctx_reg;

	u32 spi_max_frequency;
	u32 cmd;
	u32 dc;
	u32 stat;
};

#define QSPI_PID			(0x0)
#define QSPI_SYSCONFIG			(0x10)
#define QSPI_INTR_STATUS_RAW_SET	(0x20)
#define QSPI_INTR_STATUS_ENABLED_CLEAR	(0x24)
#define QSPI_INTR_ENABLE_SET_REG	(0x28)
#define QSPI_INTR_ENABLE_CLEAR_REG	(0x2c)
#define QSPI_SPI_CLOCK_CNTRL_REG	(0x40)
#define QSPI_SPI_DC_REG			(0x44)
#define QSPI_SPI_CMD_REG		(0x48)
#define QSPI_SPI_STATUS_REG		(0x4c)
#define QSPI_SPI_DATA_REG		(0x50)
#define QSPI_SPI_SETUP0_REG		(0x54)
#define QSPI_SPI_SWITCH_REG		(0x64)
#define QSPI_SPI_SETUP1_REG		(0x58)
#define QSPI_SPI_SETUP2_REG		(0x5c)
#define QSPI_SPI_SETUP3_REG		(0x60)
#define QSPI_SPI_DATA_REG_1		(0x68)
#define QSPI_SPI_DATA_REG_2		(0x6c)
#define QSPI_SPI_DATA_REG_3		(0x70)

#define QSPI_COMPLETION_TIMEOUT		msecs_to_jiffies(2000)

#define QSPI_FCLK			192000000

/* Clock Control */
#define QSPI_CLK_EN			(1 << 31)
#define QSPI_CLK_DIV_MAX		0xffff

/* Command */
#define QSPI_EN_CS(n)			(n << 28)
#define QSPI_WLEN(n)			((n - 1) << 19)
#define QSPI_3_PIN			(1 << 18)
#define QSPI_RD_SNGL			(1 << 16)
#define QSPI_WR_SNGL			(2 << 16)
#define QSPI_RD_DUAL			(3 << 16)
#define QSPI_RD_QUAD			(7 << 16)
#define QSPI_INVAL			(4 << 16)
#define QSPI_WC_CMD_INT_EN			(1 << 14)
#define QSPI_FLEN(n)			((n - 1) << 0)

/* STATUS REGISTER */
#define WC				0x02

/* INTERRUPT REGISTER */
#define QSPI_WC_INT_EN				(1 << 1)
#define QSPI_WC_INT_DISABLE			(1 << 1)

/* Device Control */
#define QSPI_DD(m, n)			(m << (3 + n * 8))
#define QSPI_CKPHA(n)			(1 << (2 + n * 8))
#define QSPI_CSPOL(n)			(1 << (1 + n * 8))
#define QSPI_CKPOL(n)			(1 << (n * 8))

#define	QSPI_FRAME			4096

#define QSPI_AUTOSUSPEND_TIMEOUT         2000

static inline unsigned long ti_qspi_read(struct ti_qspi *qspi,
		unsigned long reg)
{
	return readl(qspi->base + reg);
}

static inline void ti_qspi_write(struct ti_qspi *qspi,
		unsigned long val, unsigned long reg)
{
	writel(val, qspi->base + reg);
}

static int ti_qspi_setup(struct spi_device *spi)
{
	struct ti_qspi	*qspi = spi_master_get_devdata(spi->master);
	struct ti_qspi_regs *ctx_reg = &qspi->ctx_reg;
	int clk_div = 0, ret;
	u32 clk_ctrl_reg, clk_rate, clk_mask;

	if (spi->master->busy) {
		dev_dbg(qspi->dev, "master busy doing other trasnfers\n");
		return -EBUSY;
	}

	if (!qspi->spi_max_frequency) {
		dev_err(qspi->dev, "spi max frequency not defined\n");
		return -EINVAL;
	}

	clk_rate = clk_get_rate(qspi->fclk);

	clk_div = DIV_ROUND_UP(clk_rate, qspi->spi_max_frequency) - 1;

	if (clk_div < 0) {
		dev_dbg(qspi->dev, "clock divider < 0, using /1 divider\n");
		return -EINVAL;
	}

	if (clk_div > QSPI_CLK_DIV_MAX) {
		dev_dbg(qspi->dev, "clock divider >%d , using /%d divider\n",
				QSPI_CLK_DIV_MAX, QSPI_CLK_DIV_MAX + 1);
		return -EINVAL;
	}

	dev_dbg(qspi->dev, "hz: %d, clock divider %d\n",
			qspi->spi_max_frequency, clk_div);

	ret = pm_runtime_get_sync(qspi->dev);
	if (ret) {
		dev_err(qspi->dev, "pm_runtime_get_sync() failed\n");
		return ret;
	}

	clk_ctrl_reg = ti_qspi_read(qspi, QSPI_SPI_CLOCK_CNTRL_REG);

	clk_ctrl_reg &= ~QSPI_CLK_EN;

	/* disable SCLK */
	ti_qspi_write(qspi, clk_ctrl_reg, QSPI_SPI_CLOCK_CNTRL_REG);

	/* enable SCLK */
	clk_mask = QSPI_CLK_EN | clk_div;
	ti_qspi_write(qspi, clk_mask, QSPI_SPI_CLOCK_CNTRL_REG);
	ctx_reg->clkctrl = clk_mask;

	pm_runtime_mark_last_busy(qspi->dev);
	ret = pm_runtime_put_autosuspend(qspi->dev);
	if (ret < 0) {
		dev_err(qspi->dev, "pm_runtime_put_autosuspend() failed\n");
		return ret;
	}

	return 0;
}

static void ti_qspi_restore_ctx(struct ti_qspi *qspi)
{
	struct ti_qspi_regs *ctx_reg = &qspi->ctx_reg;

	ti_qspi_write(qspi, ctx_reg->clkctrl, QSPI_SPI_CLOCK_CNTRL_REG);
}

static int qspi_write_msg(struct ti_qspi *qspi, struct spi_transfer *t)
{
	int wlen, count, ret;
	unsigned int cmd;
	const u8 *txbuf;

	txbuf = t->tx_buf;
	cmd = qspi->cmd | QSPI_WR_SNGL;
	count = t->len;
	wlen = t->bits_per_word;

	while (count) {
		switch (wlen) {
		case 8:
			dev_dbg(qspi->dev, "tx cmd %08x dc %08x data %02x\n",
					cmd, qspi->dc, *txbuf);
			writeb(*txbuf, qspi->base + QSPI_SPI_DATA_REG);
			ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG);
			ret = wait_for_completion_timeout(&qspi->transfer_complete,
					QSPI_COMPLETION_TIMEOUT);
			if (ret == 0) {
				dev_err(qspi->dev, "write timed out\n");
				return -ETIMEDOUT;
			}
			txbuf += 1;
			count -= 1;
			break;
		case 16:
			dev_dbg(qspi->dev, "tx cmd %08x dc %08x data %04x\n",
					cmd, qspi->dc, *txbuf);
			writew(*((u16 *)txbuf), qspi->base + QSPI_SPI_DATA_REG);
			ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG);
			ret = wait_for_completion_timeout(&qspi->transfer_complete,
				QSPI_COMPLETION_TIMEOUT);
			if (ret == 0) {
				dev_err(qspi->dev, "write timed out\n");
				return -ETIMEDOUT;
			}
			txbuf += 2;
			count -= 2;
			break;
		case 32:
			dev_dbg(qspi->dev, "tx cmd %08x dc %08x data %08x\n",
					cmd, qspi->dc, *txbuf);
			writel(*((u32 *)txbuf), qspi->base + QSPI_SPI_DATA_REG);
			ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG);
			ret = wait_for_completion_timeout(&qspi->transfer_complete,
				QSPI_COMPLETION_TIMEOUT);
			if (ret == 0) {
				dev_err(qspi->dev, "write timed out\n");
				return -ETIMEDOUT;
			}
			txbuf += 4;
			count -= 4;
			break;
		}
	}

	return 0;
}

static int qspi_read_msg(struct ti_qspi *qspi, struct spi_transfer *t)
{
	int wlen, count, ret;
	unsigned int cmd;
	u8 *rxbuf;

	rxbuf = t->rx_buf;
	cmd = qspi->cmd;
	switch (t->rx_nbits) {
	case SPI_NBITS_DUAL:
		cmd |= QSPI_RD_DUAL;
		break;
	case SPI_NBITS_QUAD:
		cmd |= QSPI_RD_QUAD;
		break;
	default:
		cmd |= QSPI_RD_SNGL;
		break;
	}
	count = t->len;
	wlen = t->bits_per_word;

	while (count) {
		dev_dbg(qspi->dev, "rx cmd %08x dc %08x\n", cmd, qspi->dc);
		ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG);
		ret = wait_for_completion_timeout(&qspi->transfer_complete,
				QSPI_COMPLETION_TIMEOUT);
		if (ret == 0) {
			dev_err(qspi->dev, "read timed out\n");
			return -ETIMEDOUT;
		}
		switch (wlen) {
		case 8:
			*rxbuf = readb(qspi->base + QSPI_SPI_DATA_REG);
			rxbuf += 1;
			count -= 1;
			break;
		case 16:
			*((u16 *)rxbuf) = readw(qspi->base + QSPI_SPI_DATA_REG);
			rxbuf += 2;
			count -= 2;
			break;
		case 32:
			*((u32 *)rxbuf) = readl(qspi->base + QSPI_SPI_DATA_REG);
			rxbuf += 4;
			count -= 4;
			break;
		}
	}

	return 0;
}

static int qspi_transfer_msg(struct ti_qspi *qspi, struct spi_transfer *t)
{
	int ret;

	if (t->tx_buf) {
		ret = qspi_write_msg(qspi, t);
		if (ret) {
			dev_dbg(qspi->dev, "Error while writing\n");
			return ret;
		}
	}

	if (t->rx_buf) {
		ret = qspi_read_msg(qspi, t);
		if (ret) {
			dev_dbg(qspi->dev, "Error while reading\n");
			return ret;
		}
	}

	return 0;
}

static int ti_qspi_start_transfer_one(struct spi_master *master,
		struct spi_message *m)
{
	struct ti_qspi *qspi = spi_master_get_devdata(master);
	struct spi_device *spi = m->spi;
	struct spi_transfer *t;
	int status = 0, ret;
	int frame_length;

	/* setup device control reg */
	qspi->dc = 0;

	if (spi->mode & SPI_CPHA)
		qspi->dc |= QSPI_CKPHA(spi->chip_select);
	if (spi->mode & SPI_CPOL)
		qspi->dc |= QSPI_CKPOL(spi->chip_select);
	if (spi->mode & SPI_CS_HIGH)
		qspi->dc |= QSPI_CSPOL(spi->chip_select);

	frame_length = (m->frame_length << 3) / spi->bits_per_word;

	frame_length = clamp(frame_length, 0, QSPI_FRAME);

	/* setup command reg */
	qspi->cmd = 0;
	qspi->cmd |= QSPI_EN_CS(spi->chip_select);
	qspi->cmd |= QSPI_FLEN(frame_length);
	qspi->cmd |= QSPI_WC_CMD_INT_EN;

	ti_qspi_write(qspi, QSPI_WC_INT_EN, QSPI_INTR_ENABLE_SET_REG);
	ti_qspi_write(qspi, qspi->dc, QSPI_SPI_DC_REG);

	mutex_lock(&qspi->list_lock);

	list_for_each_entry(t, &m->transfers, transfer_list) {
		qspi->cmd |= QSPI_WLEN(t->bits_per_word);

		ret = qspi_transfer_msg(qspi, t);
		if (ret) {
			dev_dbg(qspi->dev, "transfer message failed\n");
			return -EINVAL;
		}

		m->actual_length += t->len;
	}

	mutex_unlock(&qspi->list_lock);

	m->status = status;
	spi_finalize_current_message(master);

	ti_qspi_write(qspi, qspi->cmd | QSPI_INVAL, QSPI_SPI_CMD_REG);

	return status;
}

static irqreturn_t ti_qspi_isr(int irq, void *dev_id)
{
	struct ti_qspi *qspi = dev_id;
	u16 int_stat;

	irqreturn_t ret = IRQ_HANDLED;

	spin_lock(&qspi->lock);

	int_stat = ti_qspi_read(qspi, QSPI_INTR_STATUS_ENABLED_CLEAR);
	qspi->stat = ti_qspi_read(qspi, QSPI_SPI_STATUS_REG);

	if (!int_stat) {
		dev_dbg(qspi->dev, "No IRQ triggered\n");
		ret = IRQ_NONE;
		goto out;
	}

	ret = IRQ_WAKE_THREAD;

	ti_qspi_write(qspi, QSPI_WC_INT_DISABLE, QSPI_INTR_ENABLE_CLEAR_REG);
	ti_qspi_write(qspi, QSPI_WC_INT_DISABLE,
				QSPI_INTR_STATUS_ENABLED_CLEAR);

out:
	spin_unlock(&qspi->lock);

	return ret;
}

static irqreturn_t ti_qspi_threaded_isr(int this_irq, void *dev_id)
{
	struct ti_qspi *qspi = dev_id;
	unsigned long flags;

	spin_lock_irqsave(&qspi->lock, flags);

	if (qspi->stat & WC)
		complete(&qspi->transfer_complete);

	spin_unlock_irqrestore(&qspi->lock, flags);

	ti_qspi_write(qspi, QSPI_WC_INT_EN, QSPI_INTR_ENABLE_SET_REG);

	return IRQ_HANDLED;
}

static int ti_qspi_runtime_resume(struct device *dev)
{
	struct ti_qspi      *qspi;
	struct spi_master       *master;

	master = dev_get_drvdata(dev);
	qspi = spi_master_get_devdata(master);
	ti_qspi_restore_ctx(qspi);

	return 0;
}

static const struct of_device_id ti_qspi_match[] = {
	{.compatible = "ti,dra7xxx-qspi" },
	{.compatible = "ti,am4372-qspi" },
	{},
};
MODULE_DEVICE_TABLE(of, ti_qspi_match);

static int ti_qspi_probe(struct platform_device *pdev)
{
	struct  ti_qspi *qspi;
	struct spi_master *master;
	struct resource         *r;
	struct device_node *np = pdev->dev.of_node;
	u32 max_freq;
	int ret = 0, num_cs, irq;

	master = spi_alloc_master(&pdev->dev, sizeof(*qspi));
	if (!master)
		return -ENOMEM;

	master->mode_bits = SPI_CPOL | SPI_CPHA;

	master->bus_num = -1;
	master->flags = SPI_MASTER_HALF_DUPLEX;
	master->setup = ti_qspi_setup;
	master->auto_runtime_pm = true;
	master->transfer_one_message = ti_qspi_start_transfer_one;
	master->dev.of_node = pdev->dev.of_node;
	master->bits_per_word_mask = BIT(32 - 1) | BIT(16 - 1) | BIT(8 - 1);

	if (!of_property_read_u32(np, "num-cs", &num_cs))
		master->num_chipselect = num_cs;

	platform_set_drvdata(pdev, master);

	qspi = spi_master_get_devdata(master);
	qspi->master = master;
	qspi->dev = &pdev->dev;

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
		dev_err(&pdev->dev, "no irq resource?\n");
		return irq;
	}

	spin_lock_init(&qspi->lock);
	mutex_init(&qspi->list_lock);

	qspi->base = devm_ioremap_resource(&pdev->dev, r);
	if (IS_ERR(qspi->base)) {
		ret = PTR_ERR(qspi->base);
		goto free_master;
	}

	ret = devm_request_threaded_irq(&pdev->dev, irq, ti_qspi_isr,
			ti_qspi_threaded_isr, 0,
			dev_name(&pdev->dev), qspi);
	if (ret < 0) {
		dev_err(&pdev->dev, "Failed to register ISR for IRQ %d\n",
				irq);
		goto free_master;
	}

	qspi->fclk = devm_clk_get(&pdev->dev, "fck");
	if (IS_ERR(qspi->fclk)) {
		ret = PTR_ERR(qspi->fclk);
		dev_err(&pdev->dev, "could not get clk: %d\n", ret);
	}

	init_completion(&qspi->transfer_complete);

	pm_runtime_use_autosuspend(&pdev->dev);
	pm_runtime_set_autosuspend_delay(&pdev->dev, QSPI_AUTOSUSPEND_TIMEOUT);
	pm_runtime_enable(&pdev->dev);

	if (!of_property_read_u32(np, "spi-max-frequency", &max_freq))
		qspi->spi_max_frequency = max_freq;

	ret = spi_register_master(master);
	if (ret)
		goto free_master;

	return 0;

free_master:
	spi_master_put(master);
	return ret;
}

static int ti_qspi_remove(struct platform_device *pdev)
{
	struct	ti_qspi *qspi = platform_get_drvdata(pdev);

	spi_unregister_master(qspi->master);

	return 0;
}

static const struct dev_pm_ops ti_qspi_pm_ops = {
	.runtime_resume = ti_qspi_runtime_resume,
};

static struct platform_driver ti_qspi_driver = {
	.probe	= ti_qspi_probe,
	.remove	= ti_qspi_remove,
	.driver = {
		.name	= "ti,dra7xxx-qspi",
		.owner	= THIS_MODULE,
		.pm =   &ti_qspi_pm_ops,
		.of_match_table = ti_qspi_match,
	}
};

module_platform_driver(ti_qspi_driver);

MODULE_AUTHOR("Sourav Poddar <sourav.poddar@ti.com>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("TI QSPI controller driver");