// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  SGI Volume Button interface driver
 *
 *  Copyright (C) 2008  Thomas Bogendoerfer <tsbogend@alpha.franken.de>
 */
#include <linux/input.h>
#include <linux/ioport.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#ifdef CONFIG_SGI_IP22
#include <asm/sgi/ioc.h>

static inline u8 button_status(void)
{
        u8 status;

        status = readb(&sgioc->panel) ^ 0xa0;
        return ((status & 0x80) >> 6) | ((status & 0x20) >> 5);
}
#endif

#ifdef CONFIG_SGI_IP32
#include <asm/ip32/mace.h>

static inline u8 button_status(void)
{
        u64 status;

        status = readq(&mace->perif.audio.control);
        writeq(status & ~(3U << 23), &mace->perif.audio.control);

        return (status >> 23) & 3;
}
#endif

#define BUTTONS_POLL_INTERVAL   30      /* msec */
#define BUTTONS_COUNT_THRESHOLD 3

static const unsigned short sgi_map[] = {
        KEY_VOLUMEDOWN,
        KEY_VOLUMEUP
};

struct buttons_dev {
        unsigned short keymap[ARRAY_SIZE(sgi_map)];
        int count[ARRAY_SIZE(sgi_map)];
};

static void handle_buttons(struct input_dev *input)
{
        struct buttons_dev *bdev = input_get_drvdata(input);
        u8 status;
        int i;

        status = button_status();

        for (i = 0; i < ARRAY_SIZE(bdev->keymap); i++) {
                if (status & (1U << i)) {
                        if (++bdev->count[i] == BUTTONS_COUNT_THRESHOLD) {
                                input_event(input, EV_MSC, MSC_SCAN, i);
                                input_report_key(input, bdev->keymap[i], 1);
                                input_sync(input);
                        }
                } else {
                        if (bdev->count[i] >= BUTTONS_COUNT_THRESHOLD) {
                                input_event(input, EV_MSC, MSC_SCAN, i);
                                input_report_key(input, bdev->keymap[i], 0);
                                input_sync(input);
                        }
                        bdev->count[i] = 0;
                }
        }
}

static int sgi_buttons_probe(struct platform_device *pdev)
{
        struct buttons_dev *bdev;
        struct input_dev *input;
        int error, i;

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

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

        memcpy(bdev->keymap, sgi_map, sizeof(bdev->keymap));

        input_set_drvdata(input, bdev);

        input->name = "SGI buttons";
        input->phys = "sgi/input0";
        input->id.bustype = BUS_HOST;

        input->keycode = bdev->keymap;
        input->keycodemax = ARRAY_SIZE(bdev->keymap);
        input->keycodesize = sizeof(unsigned short);

        input_set_capability(input, EV_MSC, MSC_SCAN);
        __set_bit(EV_KEY, input->evbit);
        for (i = 0; i < ARRAY_SIZE(sgi_map); i++)
                __set_bit(bdev->keymap[i], input->keybit);
        __clear_bit(KEY_RESERVED, input->keybit);

        error = input_setup_polling(input, handle_buttons);
        if (error)
                return error;

        input_set_poll_interval(input, BUTTONS_POLL_INTERVAL);

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

        return 0;
}

static struct platform_driver sgi_buttons_driver = {
        .probe  = sgi_buttons_probe,
        .driver = {
                .name   = "sgibtns",
        },
};
module_platform_driver(sgi_buttons_driver);

MODULE_DESCRIPTION("SGI Indy/O2 volume button interface driver");
MODULE_LICENSE("GPL");