// SPDX-License-Identifier: GPL-2.0-only
/*
 * Altera University Program PS2 controller driver
 *
 * Copyright (C) 2008 Thomas Chou <thomas@wytron.com.tw>
 *
 * Based on sa1111ps2.c, which is:
 * Copyright (C) 2002 Russell King
 */

#include <linux/module.h>
#include <linux/input.h>
#include <linux/serio.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/of.h>

#define DRV_NAME "altera_ps2"

struct ps2if {
	struct serio *io;
	void __iomem *base;
};

/*
 * Read all bytes waiting in the PS2 port.  There should be
 * at the most one, but we loop for safety.
 */
static irqreturn_t altera_ps2_rxint(int irq, void *dev_id)
{
	struct ps2if *ps2if = dev_id;
	unsigned int status;
	irqreturn_t handled = IRQ_NONE;

	while ((status = readl(ps2if->base)) & 0xffff0000) {
		serio_interrupt(ps2if->io, status & 0xff, 0);
		handled = IRQ_HANDLED;
	}

	return handled;
}

/*
 * Write a byte to the PS2 port.
 */
static int altera_ps2_write(struct serio *io, unsigned char val)
{
	struct ps2if *ps2if = io->port_data;

	writel(val, ps2if->base);
	return 0;
}

static int altera_ps2_open(struct serio *io)
{
	struct ps2if *ps2if = io->port_data;

	/* clear fifo */
	while (readl(ps2if->base) & 0xffff0000)
		/* empty */;

	writel(1, ps2if->base + 4); /* enable rx irq */
	return 0;
}

static void altera_ps2_close(struct serio *io)
{
	struct ps2if *ps2if = io->port_data;

	writel(0, ps2if->base + 4); /* disable rx irq */
}

/*
 * Add one device to this driver.
 */
static int altera_ps2_probe(struct platform_device *pdev)
{
	struct ps2if *ps2if;
	struct serio *serio;
	int error, irq;

	ps2if = devm_kzalloc(&pdev->dev, sizeof(*ps2if), GFP_KERNEL);
	if (!ps2if)
		return -ENOMEM;

	ps2if->base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
	if (IS_ERR(ps2if->base))
		return PTR_ERR(ps2if->base);

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

	error = devm_request_irq(&pdev->dev, irq, altera_ps2_rxint, 0,
				 pdev->name, ps2if);
	if (error) {
		dev_err(&pdev->dev, "could not request IRQ %d\n", irq);
		return error;
	}

	serio = kzalloc_obj(*serio);
	if (!serio)
		return -ENOMEM;

	serio->id.type		= SERIO_8042;
	serio->write		= altera_ps2_write;
	serio->open		= altera_ps2_open;
	serio->close		= altera_ps2_close;
	strscpy(serio->name, dev_name(&pdev->dev), sizeof(serio->name));
	strscpy(serio->phys, dev_name(&pdev->dev), sizeof(serio->phys));
	serio->port_data	= ps2if;
	serio->dev.parent	= &pdev->dev;
	ps2if->io		= serio;

	dev_info(&pdev->dev, "base %p, irq %d\n", ps2if->base, irq);

	serio_register_port(ps2if->io);
	platform_set_drvdata(pdev, ps2if);

	return 0;
}

/*
 * Remove one device from this driver.
 */
static void altera_ps2_remove(struct platform_device *pdev)
{
	struct ps2if *ps2if = platform_get_drvdata(pdev);

	serio_unregister_port(ps2if->io);
}

#ifdef CONFIG_OF
static const struct of_device_id altera_ps2_match[] = {
	{ .compatible = "ALTR,ps2-1.0", },
	{ .compatible = "altr,ps2-1.0", },
	{},
};
MODULE_DEVICE_TABLE(of, altera_ps2_match);
#endif /* CONFIG_OF */

/*
 * Our device driver structure
 */
static struct platform_driver altera_ps2_driver = {
	.probe		= altera_ps2_probe,
	.remove		= altera_ps2_remove,
	.driver	= {
		.name	= DRV_NAME,
		.of_match_table = of_match_ptr(altera_ps2_match),
	},
};
module_platform_driver(altera_ps2_driver);

MODULE_DESCRIPTION("Altera University Program PS2 controller driver");
MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);