// SPDX-License-Identifier: GPL-2.0
//
// Driver for the Winmate FM07 front-panel keys
//
// Author: Daniel Beer <daniel.beer@tirotech.co.nz>

#include <linux/init.h>
#include <linux/module.h>
#include <linux/input.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>
#include <linux/dmi.h>
#include <linux/io.h>

#define DRV_NAME        "winmate-fm07keys"

#define PORT_CMD        0x6c
#define PORT_DATA       0x68

#define EC_ADDR_KEYS    0x3b
#define EC_CMD_READ     0x80

#define BASE_KEY        KEY_F13
#define NUM_KEYS        5

/* Typically we're done in fewer than 10 iterations */
#define LOOP_TIMEOUT    1000

static void fm07keys_poll(struct input_dev *input)
{
        uint8_t k;
        int i;

        /* Flush output buffer */
        i = 0;
        while (inb(PORT_CMD) & 0x01) {
                if (++i >= LOOP_TIMEOUT)
                        goto timeout;
                inb(PORT_DATA);
        }

        /* Send request and wait for write completion */
        outb(EC_CMD_READ, PORT_CMD);
        i = 0;
        while (inb(PORT_CMD) & 0x02)
                if (++i >= LOOP_TIMEOUT)
                        goto timeout;

        outb(EC_ADDR_KEYS, PORT_DATA);
        i = 0;
        while (inb(PORT_CMD) & 0x02)
                if (++i >= LOOP_TIMEOUT)
                        goto timeout;

        /* Wait for data ready */
        i = 0;
        while (!(inb(PORT_CMD) & 0x01))
                if (++i >= LOOP_TIMEOUT)
                        goto timeout;
        k = inb(PORT_DATA);

        /* Notify of new key states */
        for (i = 0; i < NUM_KEYS; i++) {
                input_report_key(input, BASE_KEY + i, (~k) & 1);
                k >>= 1;
        }

        input_sync(input);
        return;

timeout:
        dev_warn_ratelimited(&input->dev, "timeout polling IO memory\n");
}

static int fm07keys_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct input_dev *input;
        int ret;
        int i;

        input = devm_input_allocate_device(dev);
        if (!input) {
                dev_err(dev, "no memory for input device\n");
                return -ENOMEM;
        }

        if (!devm_request_region(dev, PORT_CMD, 1, "Winmate FM07 EC"))
                return -EBUSY;
        if (!devm_request_region(dev, PORT_DATA, 1, "Winmate FM07 EC"))
                return -EBUSY;

        input->name = "Winmate FM07 front-panel keys";
        input->phys = DRV_NAME "/input0";

        input->id.bustype = BUS_HOST;
        input->id.vendor = 0x0001;
        input->id.product = 0x0001;
        input->id.version = 0x0100;

        __set_bit(EV_KEY, input->evbit);

        for (i = 0; i < NUM_KEYS; i++)
                __set_bit(BASE_KEY + i, input->keybit);

        ret = input_setup_polling(input, fm07keys_poll);
        if (ret) {
                dev_err(dev, "unable to set up polling, err=%d\n", ret);
                return ret;
        }

        /* These are silicone buttons. They can't be pressed in rapid
         * succession too quickly, and 50 Hz seems to be an adequate
         * sampling rate without missing any events when tested.
         */
        input_set_poll_interval(input, 20);

        ret = input_register_device(input);
        if (ret) {
                dev_err(dev, "unable to register polled device, err=%d\n",
                        ret);
                return ret;
        }

        input_sync(input);
        return 0;
}

static struct platform_driver fm07keys_driver = {
        .probe          = fm07keys_probe,
        .driver         = {
                .name   = DRV_NAME
        },
};

static struct platform_device *dev;

static const struct dmi_system_id fm07keys_dmi_table[] __initconst = {
        {
                /* FM07 and FM07P */
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Winmate Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "IP30"),
                },
        },
        { }
};

MODULE_DEVICE_TABLE(dmi, fm07keys_dmi_table);

static int __init fm07keys_init(void)
{
        int ret;

        if (!dmi_check_system(fm07keys_dmi_table))
                return -ENODEV;

        ret = platform_driver_register(&fm07keys_driver);
        if (ret) {
                pr_err("fm07keys: failed to register driver, err=%d\n", ret);
                return ret;
        }

        dev = platform_device_register_simple(DRV_NAME, PLATFORM_DEVID_NONE, NULL, 0);
        if (IS_ERR(dev)) {
                ret = PTR_ERR(dev);
                pr_err("fm07keys: failed to allocate device, err = %d\n", ret);
                goto fail_register;
        }

        return 0;

fail_register:
        platform_driver_unregister(&fm07keys_driver);
        return ret;
}

static void __exit fm07keys_exit(void)
{
        platform_driver_unregister(&fm07keys_driver);
        platform_device_unregister(dev);
}

module_init(fm07keys_init);
module_exit(fm07keys_exit);

MODULE_AUTHOR("Daniel Beer <daniel.beer@tirotech.co.nz>");
MODULE_DESCRIPTION("Winmate FM07 front-panel keys driver");
MODULE_LICENSE("GPL");