/*
 *	Driver for Allwinner A10 PS2 host controller
 *
 *	Author: Vishnu Patekar <vishnupatekar0510@gmail.com>
 *		Aaron.maoye <leafy.myeh@newbietech.com>
 */

#include <linux/module.h>
#include <linux/serio.h>
#include <linux/interrupt.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>

#define DRIVER_NAME		"sun4i-ps2"

/* register offset definitions */
#define PS2_REG_GCTL		0x00	/* PS2 Module Global Control Reg */
#define PS2_REG_DATA		0x04	/* PS2 Module Data Reg		*/
#define PS2_REG_LCTL		0x08	/* PS2 Module Line Control Reg */
#define PS2_REG_LSTS		0x0C	/* PS2 Module Line Status Reg	*/
#define PS2_REG_FCTL		0x10	/* PS2 Module FIFO Control Reg */
#define PS2_REG_FSTS		0x14	/* PS2 Module FIFO Status Reg	*/
#define PS2_REG_CLKDR		0x18	/* PS2 Module Clock Divider Reg*/

/*  PS2 GLOBAL CONTROL REGISTER PS2_GCTL */
#define PS2_GCTL_INTFLAG	BIT(4)
#define PS2_GCTL_INTEN		BIT(3)
#define PS2_GCTL_RESET		BIT(2)
#define PS2_GCTL_MASTER		BIT(1)
#define PS2_GCTL_BUSEN		BIT(0)

/* PS2 LINE CONTROL REGISTER */
#define PS2_LCTL_NOACK		BIT(18)
#define PS2_LCTL_TXDTOEN	BIT(8)
#define PS2_LCTL_STOPERREN	BIT(3)
#define PS2_LCTL_ACKERREN	BIT(2)
#define PS2_LCTL_PARERREN	BIT(1)
#define PS2_LCTL_RXDTOEN	BIT(0)

/* PS2 LINE STATUS REGISTER */
#define PS2_LSTS_TXTDO		BIT(8)
#define PS2_LSTS_STOPERR	BIT(3)
#define PS2_LSTS_ACKERR		BIT(2)
#define PS2_LSTS_PARERR		BIT(1)
#define PS2_LSTS_RXTDO		BIT(0)

#define PS2_LINE_ERROR_BIT \
	(PS2_LSTS_TXTDO | PS2_LSTS_STOPERR | PS2_LSTS_ACKERR | \
	PS2_LSTS_PARERR | PS2_LSTS_RXTDO)

/* PS2 FIFO CONTROL REGISTER */
#define PS2_FCTL_TXRST		BIT(17)
#define PS2_FCTL_RXRST		BIT(16)
#define PS2_FCTL_TXUFIEN	BIT(10)
#define PS2_FCTL_TXOFIEN	BIT(9)
#define PS2_FCTL_TXRDYIEN	BIT(8)
#define PS2_FCTL_RXUFIEN	BIT(2)
#define PS2_FCTL_RXOFIEN	BIT(1)
#define PS2_FCTL_RXRDYIEN	BIT(0)

/* PS2 FIFO STATUS REGISTER */
#define PS2_FSTS_TXUF		BIT(10)
#define PS2_FSTS_TXOF		BIT(9)
#define PS2_FSTS_TXRDY		BIT(8)
#define PS2_FSTS_RXUF		BIT(2)
#define PS2_FSTS_RXOF		BIT(1)
#define PS2_FSTS_RXRDY		BIT(0)

#define PS2_FIFO_ERROR_BIT \
	(PS2_FSTS_TXUF | PS2_FSTS_TXOF | PS2_FSTS_RXUF | PS2_FSTS_RXOF)

#define PS2_SAMPLE_CLK		1000000
#define PS2_SCLK		125000

struct sun4i_ps2data {
	struct serio *serio;
	struct device *dev;

	/* IO mapping base */
	void __iomem	*reg_base;

	/* clock management */
	struct clk	*clk;

	/* irq */
	spinlock_t	lock;
	int		irq;
};

static irqreturn_t sun4i_ps2_interrupt(int irq, void *dev_id)
{
	struct sun4i_ps2data *drvdata = dev_id;
	u32 intr_status;
	u32 fifo_status;
	unsigned char byte;
	unsigned int rxflags = 0;
	u32 rval;

	spin_lock(&drvdata->lock);

	/* Get the PS/2 interrupts and clear them */
	intr_status  = readl(drvdata->reg_base + PS2_REG_LSTS);
	fifo_status  = readl(drvdata->reg_base + PS2_REG_FSTS);

	/* Check line status register */
	if (intr_status & PS2_LINE_ERROR_BIT) {
		rxflags = (intr_status & PS2_LINE_ERROR_BIT) ? SERIO_FRAME : 0;
		rxflags |= (intr_status & PS2_LSTS_PARERR) ? SERIO_PARITY : 0;
		rxflags |= (intr_status & PS2_LSTS_PARERR) ? SERIO_TIMEOUT : 0;

		rval = PS2_LSTS_TXTDO | PS2_LSTS_STOPERR | PS2_LSTS_ACKERR |
			PS2_LSTS_PARERR | PS2_LSTS_RXTDO;
		writel(rval, drvdata->reg_base + PS2_REG_LSTS);
	}

	/* Check FIFO status register */
	if (fifo_status & PS2_FIFO_ERROR_BIT) {
		rval = PS2_FSTS_TXUF | PS2_FSTS_TXOF | PS2_FSTS_TXRDY |
			PS2_FSTS_RXUF | PS2_FSTS_RXOF | PS2_FSTS_RXRDY;
		writel(rval, drvdata->reg_base + PS2_REG_FSTS);
	}

	rval = (fifo_status >> 16) & 0x3;
	while (rval--) {
		byte = readl(drvdata->reg_base + PS2_REG_DATA) & 0xff;
		serio_interrupt(drvdata->serio, byte, rxflags);
	}

	writel(intr_status, drvdata->reg_base + PS2_REG_LSTS);
	writel(fifo_status, drvdata->reg_base + PS2_REG_FSTS);

	spin_unlock(&drvdata->lock);

	return IRQ_HANDLED;
}

static int sun4i_ps2_open(struct serio *serio)
{
	struct sun4i_ps2data *drvdata = serio->port_data;
	u32 src_clk = 0;
	u32 clk_scdf;
	u32 clk_pcdf;
	u32 rval;
	unsigned long flags;

	/* Set line control and enable interrupt */
	rval = PS2_LCTL_STOPERREN | PS2_LCTL_ACKERREN
		| PS2_LCTL_PARERREN | PS2_LCTL_RXDTOEN;
	writel(rval, drvdata->reg_base + PS2_REG_LCTL);

	/* Reset FIFO */
	rval = PS2_FCTL_TXRST | PS2_FCTL_RXRST | PS2_FCTL_TXUFIEN
		| PS2_FCTL_TXOFIEN | PS2_FCTL_RXUFIEN
		| PS2_FCTL_RXOFIEN | PS2_FCTL_RXRDYIEN;

	writel(rval, drvdata->reg_base + PS2_REG_FCTL);

	src_clk = clk_get_rate(drvdata->clk);
	/* Set clock divider register */
	clk_scdf = src_clk / PS2_SAMPLE_CLK - 1;
	clk_pcdf = PS2_SAMPLE_CLK / PS2_SCLK - 1;
	rval = (clk_scdf << 8) | clk_pcdf;
	writel(rval, drvdata->reg_base + PS2_REG_CLKDR);

	/* Set global control register */
	rval = PS2_GCTL_RESET | PS2_GCTL_INTEN | PS2_GCTL_MASTER
		| PS2_GCTL_BUSEN;

	spin_lock_irqsave(&drvdata->lock, flags);
	writel(rval, drvdata->reg_base + PS2_REG_GCTL);
	spin_unlock_irqrestore(&drvdata->lock, flags);

	return 0;
}

static void sun4i_ps2_close(struct serio *serio)
{
	struct sun4i_ps2data *drvdata = serio->port_data;
	u32 rval;

	/* Shut off the interrupt */
	rval = readl(drvdata->reg_base + PS2_REG_GCTL);
	writel(rval & ~(PS2_GCTL_INTEN), drvdata->reg_base + PS2_REG_GCTL);

	synchronize_irq(drvdata->irq);
}

static int sun4i_ps2_write(struct serio *serio, unsigned char val)
{
	unsigned long expire = jiffies + msecs_to_jiffies(10000);
	struct sun4i_ps2data *drvdata = serio->port_data;

	do {
		if (readl(drvdata->reg_base + PS2_REG_FSTS) & PS2_FSTS_TXRDY) {
			writel(val, drvdata->reg_base + PS2_REG_DATA);
			return 0;
		}
	} while (time_before(jiffies, expire));

	return SERIO_TIMEOUT;
}

static int sun4i_ps2_probe(struct platform_device *pdev)
{
	struct resource *res; /* IO mem resources */
	struct sun4i_ps2data *drvdata;
	struct serio *serio;
	struct device *dev = &pdev->dev;
	int error;

	drvdata = kzalloc(sizeof(struct sun4i_ps2data), GFP_KERNEL);
	serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
	if (!drvdata || !serio) {
		error = -ENOMEM;
		goto err_free_mem;
	}

	spin_lock_init(&drvdata->lock);

	/* IO */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
		dev_err(dev, "failed to locate registers\n");
		error = -ENXIO;
		goto err_free_mem;
	}

	drvdata->reg_base = ioremap(res->start, resource_size(res));
	if (!drvdata->reg_base) {
		dev_err(dev, "failed to map registers\n");
		error = -ENOMEM;
		goto err_free_mem;
	}

	drvdata->clk = clk_get(dev, NULL);
	if (IS_ERR(drvdata->clk)) {
		error = PTR_ERR(drvdata->clk);
		dev_err(dev, "couldn't get clock %d\n", error);
		goto err_ioremap;
	}

	error = clk_prepare_enable(drvdata->clk);
	if (error) {
		dev_err(dev, "failed to enable clock %d\n", error);
		goto err_clk;
	}

	serio->id.type = SERIO_8042;
	serio->write = sun4i_ps2_write;
	serio->open = sun4i_ps2_open;
	serio->close = sun4i_ps2_close;
	serio->port_data = drvdata;
	serio->dev.parent = dev;
	strlcpy(serio->name, dev_name(dev), sizeof(serio->name));
	strlcpy(serio->phys, dev_name(dev), sizeof(serio->phys));

	/* shutoff interrupt */
	writel(0, drvdata->reg_base + PS2_REG_GCTL);

	/* Get IRQ for the device */
	drvdata->irq = platform_get_irq(pdev, 0);
	if (drvdata->irq < 0) {
		error = drvdata->irq;
		goto err_disable_clk;
	}

	drvdata->serio = serio;
	drvdata->dev = dev;

	error = request_irq(drvdata->irq, sun4i_ps2_interrupt, 0,
			    DRIVER_NAME, drvdata);
	if (error) {
		dev_err(drvdata->dev, "failed to allocate interrupt %d: %d\n",
			drvdata->irq, error);
		goto err_disable_clk;
	}

	serio_register_port(serio);
	platform_set_drvdata(pdev, drvdata);

	return 0;	/* success */

err_disable_clk:
	clk_disable_unprepare(drvdata->clk);
err_clk:
	clk_put(drvdata->clk);
err_ioremap:
	iounmap(drvdata->reg_base);
err_free_mem:
	kfree(serio);
	kfree(drvdata);
	return error;
}

static int sun4i_ps2_remove(struct platform_device *pdev)
{
	struct sun4i_ps2data *drvdata = platform_get_drvdata(pdev);

	serio_unregister_port(drvdata->serio);

	free_irq(drvdata->irq, drvdata);

	clk_disable_unprepare(drvdata->clk);
	clk_put(drvdata->clk);

	iounmap(drvdata->reg_base);

	kfree(drvdata);

	return 0;
}

static const struct of_device_id sun4i_ps2_match[] = {
	{ .compatible = "allwinner,sun4i-a10-ps2", },
	{ },
};

MODULE_DEVICE_TABLE(of, sun4i_ps2_match);

static struct platform_driver sun4i_ps2_driver = {
	.probe		= sun4i_ps2_probe,
	.remove		= sun4i_ps2_remove,
	.driver = {
		.name = DRIVER_NAME,
		.of_match_table = sun4i_ps2_match,
	},
};
module_platform_driver(sun4i_ps2_driver);

MODULE_AUTHOR("Vishnu Patekar <vishnupatekar0510@gmail.com>");
MODULE_AUTHOR("Aaron.maoye <leafy.myeh@newbietech.com>");
MODULE_DESCRIPTION("Allwinner A10/Sun4i PS/2 driver");
MODULE_LICENSE("GPL v2");