/*
 * drivers/staging/media/st-cec/stih-cec.c
 *
 * STIH4xx CEC driver
 * Copyright (C) STMicroelectronic SA 2016
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */
#include <linux/clk.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/version.h>

#include <media/cec.h>

#define CEC_NAME	"stih-cec"

/* CEC registers  */
#define CEC_CLK_DIV           0x0
#define CEC_CTRL              0x4
#define CEC_IRQ_CTRL          0x8
#define CEC_STATUS            0xC
#define CEC_EXT_STATUS        0x10
#define CEC_TX_CTRL           0x14
#define CEC_FREE_TIME_THRESH  0x18
#define CEC_BIT_TOUT_THRESH   0x1C
#define CEC_BIT_PULSE_THRESH  0x20
#define CEC_DATA              0x24
#define CEC_TX_ARRAY_CTRL     0x28
#define CEC_CTRL2             0x2C
#define CEC_TX_ERROR_STS      0x30
#define CEC_ADDR_TABLE        0x34
#define CEC_DATA_ARRAY_CTRL   0x38
#define CEC_DATA_ARRAY_STATUS 0x3C
#define CEC_TX_DATA_BASE      0x40
#define CEC_TX_DATA_TOP       0x50
#define CEC_TX_DATA_SIZE      0x1
#define CEC_RX_DATA_BASE      0x54
#define CEC_RX_DATA_TOP       0x64
#define CEC_RX_DATA_SIZE      0x1

/* CEC_CTRL2 */
#define CEC_LINE_INACTIVE_EN   BIT(0)
#define CEC_AUTO_BUS_ERR_EN    BIT(1)
#define CEC_STOP_ON_ARB_ERR_EN BIT(2)
#define CEC_TX_REQ_WAIT_EN     BIT(3)

/* CEC_DATA_ARRAY_CTRL */
#define CEC_TX_ARRAY_EN          BIT(0)
#define CEC_RX_ARRAY_EN          BIT(1)
#define CEC_TX_ARRAY_RESET       BIT(2)
#define CEC_RX_ARRAY_RESET       BIT(3)
#define CEC_TX_N_OF_BYTES_IRQ_EN BIT(4)
#define CEC_TX_STOP_ON_NACK      BIT(7)

/* CEC_TX_ARRAY_CTRL */
#define CEC_TX_N_OF_BYTES  0x1F
#define CEC_TX_START       BIT(5)
#define CEC_TX_AUTO_SOM_EN BIT(6)
#define CEC_TX_AUTO_EOM_EN BIT(7)

/* CEC_IRQ_CTRL */
#define CEC_TX_DONE_IRQ_EN   BIT(0)
#define CEC_ERROR_IRQ_EN     BIT(2)
#define CEC_RX_DONE_IRQ_EN   BIT(3)
#define CEC_RX_SOM_IRQ_EN    BIT(4)
#define CEC_RX_EOM_IRQ_EN    BIT(5)
#define CEC_FREE_TIME_IRQ_EN BIT(6)
#define CEC_PIN_STS_IRQ_EN   BIT(7)

/* CEC_CTRL */
#define CEC_IN_FILTER_EN    BIT(0)
#define CEC_PWR_SAVE_EN     BIT(1)
#define CEC_EN              BIT(4)
#define CEC_ACK_CTRL        BIT(5)
#define CEC_RX_RESET_EN     BIT(6)
#define CEC_IGNORE_RX_ERROR BIT(7)

/* CEC_STATUS */
#define CEC_TX_DONE_STS       BIT(0)
#define CEC_TX_ACK_GET_STS    BIT(1)
#define CEC_ERROR_STS         BIT(2)
#define CEC_RX_DONE_STS       BIT(3)
#define CEC_RX_SOM_STS        BIT(4)
#define CEC_RX_EOM_STS        BIT(5)
#define CEC_FREE_TIME_IRQ_STS BIT(6)
#define CEC_PIN_STS           BIT(7)
#define CEC_SBIT_TOUT_STS     BIT(8)
#define CEC_DBIT_TOUT_STS     BIT(9)
#define CEC_LPULSE_ERROR_STS  BIT(10)
#define CEC_HPULSE_ERROR_STS  BIT(11)
#define CEC_TX_ERROR          BIT(12)
#define CEC_TX_ARB_ERROR      BIT(13)
#define CEC_RX_ERROR_MIN      BIT(14)
#define CEC_RX_ERROR_MAX      BIT(15)

/* Signal free time in bit periods (2.4ms) */
#define CEC_PRESENT_INIT_SFT 7
#define CEC_NEW_INIT_SFT     5
#define CEC_RETRANSMIT_SFT   3

/* Constants for CEC_BIT_TOUT_THRESH register */
#define CEC_SBIT_TOUT_47MS BIT(1)
#define CEC_SBIT_TOUT_48MS BIT(0) | BIT(1)
#define CEC_SBIT_TOUT_50MS BIT(2)
#define CEC_DBIT_TOUT_27MS BIT(0)
#define CEC_DBIT_TOUT_28MS BIT(1)
#define CEC_DBIT_TOUT_29MS BIT(0) | BIT(1)

/* Constants for CEC_BIT_PULSE_THRESH register */
#define CEC_BIT_LPULSE_03MS BIT(1)
#define CEC_BIT_HPULSE_03MS BIT(3)

/* Constants for CEC_DATA_ARRAY_STATUS register */
#define CEC_RX_N_OF_BYTES                     0x1F
#define CEC_TX_N_OF_BYTES_SENT                BIT(5)
#define CEC_RX_OVERRUN                        BIT(6)

struct stih_cec {
	struct cec_adapter	*adap;
	struct device		*dev;
	struct clk		*clk;
	void __iomem		*regs;
	int			irq;
	u32			irq_status;
};

static int stih_cec_adap_enable(struct cec_adapter *adap, bool enable)
{
	struct stih_cec *cec = adap->priv;

	if (enable) {
		/* The doc says (input TCLK_PERIOD * CEC_CLK_DIV) = 0.1ms */
		unsigned long clk_freq = clk_get_rate(cec->clk);
		u32 cec_clk_div = clk_freq / 10000;

		writel(cec_clk_div, cec->regs + CEC_CLK_DIV);

		/* Configuration of the durations activating a timeout */
		writel(CEC_SBIT_TOUT_47MS | (CEC_DBIT_TOUT_28MS << 4),
		       cec->regs + CEC_BIT_TOUT_THRESH);

		/* Configuration of the smallest allowed duration for pulses */
		writel(CEC_BIT_LPULSE_03MS | CEC_BIT_HPULSE_03MS,
		       cec->regs + CEC_BIT_PULSE_THRESH);

		/* Minimum received bit period threshold */
		writel(BIT(5) | BIT(7), cec->regs + CEC_TX_CTRL);

		/* Configuration of transceiver data arrays */
		writel(CEC_TX_ARRAY_EN | CEC_RX_ARRAY_EN | CEC_TX_STOP_ON_NACK,
		       cec->regs + CEC_DATA_ARRAY_CTRL);

		/* Configuration of the control bits for CEC Transceiver */
		writel(CEC_IN_FILTER_EN | CEC_EN | CEC_RX_RESET_EN,
		       cec->regs + CEC_CTRL);

		/* Clear logical addresses */
		writel(0, cec->regs + CEC_ADDR_TABLE);

		/* Clear the status register */
		writel(0x0, cec->regs + CEC_STATUS);

		/* Enable the interrupts */
		writel(CEC_TX_DONE_IRQ_EN | CEC_RX_DONE_IRQ_EN |
		       CEC_RX_SOM_IRQ_EN | CEC_RX_EOM_IRQ_EN |
		       CEC_ERROR_IRQ_EN,
		       cec->regs + CEC_IRQ_CTRL);

	} else {
		/* Clear logical addresses */
		writel(0, cec->regs + CEC_ADDR_TABLE);

		/* Clear the status register */
		writel(0x0, cec->regs + CEC_STATUS);

		/* Disable the interrupts */
		writel(0, cec->regs + CEC_IRQ_CTRL);
	}

	return 0;
}

static int stih_cec_adap_log_addr(struct cec_adapter *adap, u8 logical_addr)
{
	struct stih_cec *cec = adap->priv;
	u32 reg = readl(cec->regs + CEC_ADDR_TABLE);

	reg |= 1 << logical_addr;

	if (logical_addr == CEC_LOG_ADDR_INVALID)
		reg = 0;

	writel(reg, cec->regs + CEC_ADDR_TABLE);

	return 0;
}

static int stih_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
				  u32 signal_free_time, struct cec_msg *msg)
{
	struct stih_cec *cec = adap->priv;
	int i;

	/* Copy message into registers */
	for (i = 0; i < msg->len; i++)
		writeb(msg->msg[i], cec->regs + CEC_TX_DATA_BASE + i);

	/* Start transmission, configure hardware to add start and stop bits
	 * Signal free time is handled by the hardware
	 */
	writel(CEC_TX_AUTO_SOM_EN | CEC_TX_AUTO_EOM_EN | CEC_TX_START |
	       msg->len, cec->regs + CEC_TX_ARRAY_CTRL);

	return 0;
}

static void stih_tx_done(struct stih_cec *cec, u32 status)
{
	if (status & CEC_TX_ERROR) {
		cec_transmit_done(cec->adap, CEC_TX_STATUS_ERROR, 0, 0, 0, 1);
		return;
	}

	if (status & CEC_TX_ARB_ERROR) {
		cec_transmit_done(cec->adap,
				  CEC_TX_STATUS_ARB_LOST, 1, 0, 0, 0);
		return;
	}

	if (!(status & CEC_TX_ACK_GET_STS)) {
		cec_transmit_done(cec->adap, CEC_TX_STATUS_NACK, 0, 1, 0, 0);
		return;
	}

	cec_transmit_done(cec->adap, CEC_TX_STATUS_OK, 0, 0, 0, 0);
}

static void stih_rx_done(struct stih_cec *cec, u32 status)
{
	struct cec_msg msg = {};
	u8 i;

	if (status & CEC_RX_ERROR_MIN)
		return;

	if (status & CEC_RX_ERROR_MAX)
		return;

	msg.len = readl(cec->regs + CEC_DATA_ARRAY_STATUS) & 0x1f;

	if (!msg.len)
		return;

	if (msg.len > 16)
		msg.len = 16;

	for (i = 0; i < msg.len; i++)
		msg.msg[i] = readl(cec->regs + CEC_RX_DATA_BASE + i);

	cec_received_msg(cec->adap, &msg);
}

static irqreturn_t stih_cec_irq_handler_thread(int irq, void *priv)
{
	struct stih_cec *cec = priv;

	if (cec->irq_status & CEC_TX_DONE_STS)
		stih_tx_done(cec, cec->irq_status);

	if (cec->irq_status & CEC_RX_DONE_STS)
		stih_rx_done(cec, cec->irq_status);

	cec->irq_status = 0;

	return IRQ_HANDLED;
}

static irqreturn_t stih_cec_irq_handler(int irq, void *priv)
{
	struct stih_cec *cec = priv;

	cec->irq_status = readl(cec->regs + CEC_STATUS);
	writel(cec->irq_status, cec->regs + CEC_STATUS);

	return IRQ_WAKE_THREAD;
}

static const struct cec_adap_ops sti_cec_adap_ops = {
	.adap_enable = stih_cec_adap_enable,
	.adap_log_addr = stih_cec_adap_log_addr,
	.adap_transmit = stih_cec_adap_transmit,
};

static int stih_cec_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct resource *res;
	struct stih_cec *cec;
	int ret;

	cec = devm_kzalloc(dev, sizeof(*cec), GFP_KERNEL);
	if (!cec)
		return -ENOMEM;

	cec->dev = dev;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	cec->regs = devm_ioremap_resource(dev, res);
	if (IS_ERR(cec->regs))
		return PTR_ERR(cec->regs);

	cec->irq = platform_get_irq(pdev, 0);
	if (cec->irq < 0)
		return cec->irq;

	ret = devm_request_threaded_irq(dev, cec->irq, stih_cec_irq_handler,
					stih_cec_irq_handler_thread, 0,
					pdev->name, cec);
	if (ret)
		return ret;

	cec->clk = devm_clk_get(dev, "cec-clk");
	if (IS_ERR(cec->clk)) {
		dev_err(dev, "Cannot get cec clock\n");
		return PTR_ERR(cec->clk);
	}

	cec->adap = cec_allocate_adapter(&sti_cec_adap_ops, cec,
			CEC_NAME,
			CEC_CAP_LOG_ADDRS | CEC_CAP_PASSTHROUGH |
			CEC_CAP_PHYS_ADDR | CEC_CAP_TRANSMIT,
			1, &pdev->dev);
	ret = PTR_ERR_OR_ZERO(cec->adap);
	if (ret)
		return ret;

	ret = cec_register_adapter(cec->adap);
	if (ret) {
		cec_delete_adapter(cec->adap);
		return ret;
	}

	platform_set_drvdata(pdev, cec);
	return 0;
}

static int stih_cec_remove(struct platform_device *pdev)
{
	return 0;
}

static const struct of_device_id stih_cec_match[] = {
	{
		.compatible	= "st,stih-cec",
	},
	{},
};

static struct platform_driver stih_cec_pdrv = {
	.probe	= stih_cec_probe,
	.remove = stih_cec_remove,
	.driver = {
		.name		= CEC_NAME,
		.of_match_table	= stih_cec_match,
	},
};

module_platform_driver(stih_cec_pdrv);

MODULE_AUTHOR("Benjamin Gaignard <benjamin.gaignard@linaro.org>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("STIH4xx CEC driver");