/*
 * 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
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

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

#define DRV_NAME "altera_ps2"

struct ps2if {
	struct serio *io;
	struct resource *iomem_res;
	void __iomem *base;
	unsigned irq;
};

/*
 * 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;
	int 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); /* 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;

	ps2if = kzalloc(sizeof(struct ps2if), GFP_KERNEL);
	serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
	if (!ps2if || !serio) {
		error = -ENOMEM;
		goto err_free_mem;
	}

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

	ps2if->iomem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (ps2if->iomem_res == NULL) {
		error = -ENOENT;
		goto err_free_mem;
	}

	ps2if->irq  = platform_get_irq(pdev, 0);
	if (ps2if->irq < 0) {
		error = -ENXIO;
		goto err_free_mem;
	}

	if (!request_mem_region(ps2if->iomem_res->start,
				resource_size(ps2if->iomem_res), pdev->name)) {
		error = -EBUSY;
		goto err_free_mem;
	}

	ps2if->base = ioremap(ps2if->iomem_res->start,
			      resource_size(ps2if->iomem_res));
	if (!ps2if->base) {
		error = -ENOMEM;
		goto err_free_res;
	}

	error = request_irq(ps2if->irq, altera_ps2_rxint, 0, pdev->name, ps2if);
	if (error) {
		dev_err(&pdev->dev, "could not allocate IRQ %d: %d\n",
			ps2if->irq, error);
		goto err_unmap;
	}

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

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

	return 0;

 err_unmap:
	iounmap(ps2if->base);
 err_free_res:
	release_mem_region(ps2if->iomem_res->start,
			   resource_size(ps2if->iomem_res));
 err_free_mem:
	kfree(ps2if);
	kfree(serio);
	return error;
}

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

	platform_set_drvdata(pdev, NULL);
	serio_unregister_port(ps2if->io);
	free_irq(ps2if->irq, ps2if);
	iounmap(ps2if->base);
	release_mem_region(ps2if->iomem_res->start,
			   resource_size(ps2if->iomem_res));
	kfree(ps2if);

	return 0;
}

/*
 * Our device driver structure
 */
static struct platform_driver altera_ps2_driver = {
	.probe		= altera_ps2_probe,
	.remove		= altera_ps2_remove,
	.driver	= {
		.name	= DRV_NAME,
	},
};

static int __init altera_ps2_init(void)
{
	return platform_driver_register(&altera_ps2_driver);
}

static void __exit altera_ps2_exit(void)
{
	platform_driver_unregister(&altera_ps2_driver);
}

module_init(altera_ps2_init);
module_exit(altera_ps2_exit);

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