/*
 * PXA930 track ball mouse driver
 *
 * Copyright (C) 2007 Marvell International Ltd.
 * 2008-02-28: Yong Yao <yaoyong@marvell.com>
 *             initial version
 *
 *  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/init.h>
#include <linux/input.h>
#include <linux/version.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/slab.h>

#include <mach/hardware.h>
#include <mach/pxa930_trkball.h>

/* Trackball Controller Register Definitions */
#define TBCR            (0x000C)
#define TBCNTR          (0x0010)
#define TBSBC           (0x0014)

#define TBCR_TBRST      (1 << 1)
#define TBCR_TBSB       (1 << 10)

#define TBCR_Y_FLT(n)   (((n) & 0xf) << 6)
#define TBCR_X_FLT(n)   (((n) & 0xf) << 2)

#define TBCNTR_YM(n)    (((n) >> 24) & 0xff)
#define TBCNTR_YP(n)    (((n) >> 16) & 0xff)
#define TBCNTR_XM(n)    (((n) >> 8) & 0xff)
#define TBCNTR_XP(n)    ((n) & 0xff)

#define TBSBC_TBSBC     (0x1)

struct pxa930_trkball {
        struct pxa930_trkball_platform_data *pdata;

        /* Memory Mapped Register */
        struct resource *mem;
        void __iomem *mmio_base;

        struct input_dev *input;
};

static irqreturn_t pxa930_trkball_interrupt(int irq, void *dev_id)
{
        struct pxa930_trkball *trkball = dev_id;
        struct input_dev *input = trkball->input;
        int tbcntr, x, y;

        /* According to the spec software must read TBCNTR twice:
         * if the read value is the same, the reading is valid
         */
        tbcntr = __raw_readl(trkball->mmio_base + TBCNTR);

        if (tbcntr == __raw_readl(trkball->mmio_base + TBCNTR)) {
                x = (TBCNTR_XP(tbcntr) - TBCNTR_XM(tbcntr)) / 2;
                y = (TBCNTR_YP(tbcntr) - TBCNTR_YM(tbcntr)) / 2;

                input_report_rel(input, REL_X, x);
                input_report_rel(input, REL_Y, y);
                input_sync(input);
        }

        __raw_writel(TBSBC_TBSBC, trkball->mmio_base + TBSBC);
        __raw_writel(0, trkball->mmio_base + TBSBC);

        return IRQ_HANDLED;
}

/* For TBCR, we need to wait for a while to make sure it has been modified. */
static int write_tbcr(struct pxa930_trkball *trkball, int v)
{
        int i = 100;

        __raw_writel(v, trkball->mmio_base + TBCR);

        while (--i) {
                if (__raw_readl(trkball->mmio_base + TBCR) == v)
                        break;
                msleep(1);
        }

        if (i == 0) {
                pr_err("%s: timed out writing TBCR(%x)!\n", __func__, v);
                return -ETIMEDOUT;
        }

        return 0;
}

static void pxa930_trkball_config(struct pxa930_trkball *trkball)
{
        uint32_t tbcr;

        /* According to spec, need to write the filters of x,y to 0xf first! */
        tbcr = __raw_readl(trkball->mmio_base + TBCR);
        write_tbcr(trkball, tbcr | TBCR_X_FLT(0xf) | TBCR_Y_FLT(0xf));
        write_tbcr(trkball, TBCR_X_FLT(trkball->pdata->x_filter) |
                            TBCR_Y_FLT(trkball->pdata->y_filter));

        /* According to spec, set TBCR_TBRST first, before clearing it! */
        tbcr = __raw_readl(trkball->mmio_base + TBCR);
        write_tbcr(trkball, tbcr | TBCR_TBRST);
        write_tbcr(trkball, tbcr & ~TBCR_TBRST);

        __raw_writel(TBSBC_TBSBC, trkball->mmio_base + TBSBC);
        __raw_writel(0, trkball->mmio_base + TBSBC);

        pr_debug("%s: final TBCR=%x!\n", __func__,
                 __raw_readl(trkball->mmio_base + TBCR));
}

static int pxa930_trkball_open(struct input_dev *dev)
{
        struct pxa930_trkball *trkball = input_get_drvdata(dev);

        pxa930_trkball_config(trkball);

        return 0;
}

static void pxa930_trkball_disable(struct pxa930_trkball *trkball)
{
        uint32_t tbcr = __raw_readl(trkball->mmio_base + TBCR);

        /* Held in reset, gate the 32-KHz input clock off */
        write_tbcr(trkball, tbcr | TBCR_TBRST);
}

static void pxa930_trkball_close(struct input_dev *dev)
{
        struct pxa930_trkball *trkball = input_get_drvdata(dev);

        pxa930_trkball_disable(trkball);
}

static int __devinit pxa930_trkball_probe(struct platform_device *pdev)
{
        struct pxa930_trkball *trkball;
        struct input_dev *input;
        struct resource *res;
        int irq, error;

        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                dev_err(&pdev->dev, "failed to get trkball irq\n");
                return -ENXIO;
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                dev_err(&pdev->dev, "failed to get register memory\n");
                return -ENXIO;
        }

        trkball = kzalloc(sizeof(struct pxa930_trkball), GFP_KERNEL);
        if (!trkball)
                return -ENOMEM;

        trkball->pdata = pdev->dev.platform_data;
        if (!trkball->pdata) {
                dev_err(&pdev->dev, "no platform data defined\n");
                error = -EINVAL;
                goto failed;
        }

        trkball->mmio_base = ioremap_nocache(res->start, resource_size(res));
        if (!trkball->mmio_base) {
                dev_err(&pdev->dev, "failed to ioremap registers\n");
                error = -ENXIO;
                goto failed;
        }

        /* held the module in reset, will be enabled in open() */
        pxa930_trkball_disable(trkball);

        error = request_irq(irq, pxa930_trkball_interrupt, IRQF_DISABLED,
                            pdev->name, trkball);
        if (error) {
                dev_err(&pdev->dev, "failed to request irq: %d\n", error);
                goto failed_free_io;
        }

        platform_set_drvdata(pdev, trkball);

        input = input_allocate_device();
        if (!input) {
                dev_err(&pdev->dev, "failed to allocate input device\n");
                error = -ENOMEM;
                goto failed_free_irq;
        }

        input->name = pdev->name;
        input->id.bustype = BUS_HOST;
        input->open = pxa930_trkball_open;
        input->close = pxa930_trkball_close;
        input->dev.parent = &pdev->dev;
        input_set_drvdata(input, trkball);

        trkball->input = input;

        input_set_capability(input, EV_REL, REL_X);
        input_set_capability(input, EV_REL, REL_Y);

        error = input_register_device(input);
        if (error) {
                dev_err(&pdev->dev, "unable to register input device\n");
                goto failed_free_input;
        }

        return 0;

failed_free_input:
        input_free_device(input);
failed_free_irq:
        free_irq(irq, trkball);
failed_free_io:
        iounmap(trkball->mmio_base);
failed:
        kfree(trkball);
        return error;
}

static int __devexit pxa930_trkball_remove(struct platform_device *pdev)
{
        struct pxa930_trkball *trkball = platform_get_drvdata(pdev);
        int irq = platform_get_irq(pdev, 0);

        input_unregister_device(trkball->input);
        free_irq(irq, trkball);
        iounmap(trkball->mmio_base);
        kfree(trkball);

        return 0;
}

static struct platform_driver pxa930_trkball_driver = {
        .driver         = {
                .name   = "pxa930-trkball",
        },
        .probe          = pxa930_trkball_probe,
        .remove         = __devexit_p(pxa930_trkball_remove),
};

static int __init pxa930_trkball_init(void)
{
        return platform_driver_register(&pxa930_trkball_driver);
}

static void __exit pxa930_trkball_exit(void)
{
        platform_driver_unregister(&pxa930_trkball_driver);
}

module_init(pxa930_trkball_init);
module_exit(pxa930_trkball_exit);

MODULE_AUTHOR("Yong Yao <yaoyong@marvell.com>");
MODULE_DESCRIPTION("PXA930 Trackball Mouse Driver");
MODULE_LICENSE("GPL");