/*
 * Copyright (C) 2007 Google, Inc.
 * Copyright (C) 2012 Intel, Inc.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/types.h>
#include <linux/input.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/acpi.h>

enum {
        REG_READ        = 0x00,
        REG_SET_PAGE    = 0x00,
        REG_LEN         = 0x04,
        REG_DATA        = 0x08,

        PAGE_NAME       = 0x00000,
        PAGE_EVBITS     = 0x10000,
        PAGE_ABSDATA    = 0x20000 | EV_ABS,
};

struct event_dev {
        struct input_dev *input;
        int irq;
        void __iomem *addr;
        char name[0];
};

static irqreturn_t events_interrupt(int irq, void *dev_id)
{
        struct event_dev *edev = dev_id;
        unsigned int type, code, value;

        type = __raw_readl(edev->addr + REG_READ);
        code = __raw_readl(edev->addr + REG_READ);
        value = __raw_readl(edev->addr + REG_READ);

        input_event(edev->input, type, code, value);
        input_sync(edev->input);
        return IRQ_HANDLED;
}

static void events_import_bits(struct event_dev *edev,
                        unsigned long bits[], unsigned int type, size_t count)
{
        void __iomem *addr = edev->addr;
        int i, j;
        size_t size;
        uint8_t val;

        __raw_writel(PAGE_EVBITS | type, addr + REG_SET_PAGE);

        size = __raw_readl(addr + REG_LEN) * 8;
        if (size < count)
                count = size;

        addr += REG_DATA;
        for (i = 0; i < count; i += 8) {
                val = __raw_readb(addr++);
                for (j = 0; j < 8; j++)
                        if (val & 1 << j)
                                set_bit(i + j, bits);
        }
}

static void events_import_abs_params(struct event_dev *edev)
{
        struct input_dev *input_dev = edev->input;
        void __iomem *addr = edev->addr;
        u32 val[4];
        int count;
        int i, j;

        __raw_writel(PAGE_ABSDATA, addr + REG_SET_PAGE);

        count = __raw_readl(addr + REG_LEN) / sizeof(val);
        if (count > ABS_MAX)
                count = ABS_MAX;

        for (i = 0; i < count; i++) {
                if (!test_bit(i, input_dev->absbit))
                        continue;

                for (j = 0; j < ARRAY_SIZE(val); j++) {
                        int offset = (i * ARRAY_SIZE(val) + j) * sizeof(u32);

                        val[j] = __raw_readl(edev->addr + REG_DATA + offset);
                }

                input_set_abs_params(input_dev, i,
                                     val[0], val[1], val[2], val[3]);
        }
}

static int events_probe(struct platform_device *pdev)
{
        struct input_dev *input_dev;
        struct event_dev *edev;
        struct resource *res;
        unsigned int keymapnamelen;
        void __iomem *addr;
        int irq;
        int i;
        int error;

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

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -EINVAL;

        addr = devm_ioremap(&pdev->dev, res->start, 4096);
        if (!addr)
                return -ENOMEM;

        __raw_writel(PAGE_NAME, addr + REG_SET_PAGE);
        keymapnamelen = __raw_readl(addr + REG_LEN);

        edev = devm_kzalloc(&pdev->dev,
                            sizeof(struct event_dev) + keymapnamelen + 1,
                            GFP_KERNEL);
        if (!edev)
                return -ENOMEM;

        input_dev = devm_input_allocate_device(&pdev->dev);
        if (!input_dev)
                return -ENOMEM;

        edev->input = input_dev;
        edev->addr = addr;
        edev->irq = irq;

        for (i = 0; i < keymapnamelen; i++)
                edev->name[i] = __raw_readb(edev->addr + REG_DATA + i);

        pr_debug("%s: keymap=%s\n", __func__, edev->name);

        input_dev->name = edev->name;
        input_dev->id.bustype = BUS_HOST;

        events_import_bits(edev, input_dev->evbit, EV_SYN, EV_MAX);
        events_import_bits(edev, input_dev->keybit, EV_KEY, KEY_MAX);
        events_import_bits(edev, input_dev->relbit, EV_REL, REL_MAX);
        events_import_bits(edev, input_dev->absbit, EV_ABS, ABS_MAX);
        events_import_bits(edev, input_dev->mscbit, EV_MSC, MSC_MAX);
        events_import_bits(edev, input_dev->ledbit, EV_LED, LED_MAX);
        events_import_bits(edev, input_dev->sndbit, EV_SND, SND_MAX);
        events_import_bits(edev, input_dev->ffbit, EV_FF, FF_MAX);
        events_import_bits(edev, input_dev->swbit, EV_SW, SW_MAX);

        events_import_abs_params(edev);

        error = devm_request_irq(&pdev->dev, edev->irq, events_interrupt, 0,
                                 "goldfish-events-keypad", edev);
        if (error)
                return error;

        error = input_register_device(input_dev);
        if (error)
                return error;

        return 0;
}

static const struct of_device_id goldfish_events_of_match[] = {
        { .compatible = "google,goldfish-events-keypad", },
        {},
};
MODULE_DEVICE_TABLE(of, goldfish_events_of_match);

#ifdef CONFIG_ACPI
static const struct acpi_device_id goldfish_events_acpi_match[] = {
        { "GFSH0002", 0 },
        { },
};
MODULE_DEVICE_TABLE(acpi, goldfish_events_acpi_match);
#endif

static struct platform_driver events_driver = {
        .probe  = events_probe,
        .driver = {
                .name   = "goldfish_events",
                .of_match_table = goldfish_events_of_match,
                .acpi_match_table = ACPI_PTR(goldfish_events_acpi_match),
        },
};

module_platform_driver(events_driver);

MODULE_AUTHOR("Brian Swetland");
MODULE_DESCRIPTION("Goldfish Event Device");
MODULE_LICENSE("GPL");