// SPDX-License-Identifier: GPL-2.0+
/*
 *  HID driver for Cougar 500k Gaming Keyboard
 *
 *  Copyright (c) 2018 Daniel M. Lambea <dmlambea@gmail.com>
 */

#include <linux/hid.h>
#include <linux/module.h>
#include <linux/printk.h>

#include "hid-ids.h"

MODULE_AUTHOR("Daniel M. Lambea <dmlambea@gmail.com>");
MODULE_DESCRIPTION("Cougar 500k Gaming Keyboard");
MODULE_LICENSE("GPL");
MODULE_INFO(key_mappings, "G1-G6 are mapped to F13-F18");

static bool g6_is_space = true;
MODULE_PARM_DESC(g6_is_space,
        "If true, G6 programmable key sends SPACE instead of F18 (default=true)");

#define COUGAR_VENDOR_USAGE     0xff00ff00

#define COUGAR_FIELD_CODE       1
#define COUGAR_FIELD_ACTION     2

#define COUGAR_KEY_G1           0x83
#define COUGAR_KEY_G2           0x84
#define COUGAR_KEY_G3           0x85
#define COUGAR_KEY_G4           0x86
#define COUGAR_KEY_G5           0x87
#define COUGAR_KEY_G6           0x78
#define COUGAR_KEY_FN           0x0d
#define COUGAR_KEY_MR           0x6f
#define COUGAR_KEY_M1           0x80
#define COUGAR_KEY_M2           0x81
#define COUGAR_KEY_M3           0x82
#define COUGAR_KEY_LEDS         0x67
#define COUGAR_KEY_LOCK         0x6e


/* Default key mappings. The special key COUGAR_KEY_G6 is defined first
 * because it is more frequent to use the spacebar rather than any other
 * special keys. Depending on the value of the parameter 'g6_is_space',
 * the mapping will be updated in the probe function.
 */
static unsigned char cougar_mapping[][2] = {
        { COUGAR_KEY_G6,   KEY_SPACE },
        { COUGAR_KEY_G1,   KEY_F13 },
        { COUGAR_KEY_G2,   KEY_F14 },
        { COUGAR_KEY_G3,   KEY_F15 },
        { COUGAR_KEY_G4,   KEY_F16 },
        { COUGAR_KEY_G5,   KEY_F17 },
        { COUGAR_KEY_LOCK, KEY_SCREENLOCK },
/* The following keys are handled by the hardware itself, so no special
 * treatment is required:
        { COUGAR_KEY_FN, KEY_RESERVED },
        { COUGAR_KEY_MR, KEY_RESERVED },
        { COUGAR_KEY_M1, KEY_RESERVED },
        { COUGAR_KEY_M2, KEY_RESERVED },
        { COUGAR_KEY_M3, KEY_RESERVED },
        { COUGAR_KEY_LEDS, KEY_RESERVED },
*/
        { 0, 0 },
};

struct cougar_shared {
        struct list_head list;
        struct kref kref;
        bool enabled;
        struct hid_device *dev;
        struct input_dev *input;
};

struct cougar {
        bool special_intf;
        struct cougar_shared *shared;
};

static LIST_HEAD(cougar_udev_list);
static DEFINE_MUTEX(cougar_udev_list_lock);

/**
 * cougar_fix_g6_mapping - configure the mapping for key G6/Spacebar
 */
static void cougar_fix_g6_mapping(void)
{
        int i;

        for (i = 0; cougar_mapping[i][0]; i++) {
                if (cougar_mapping[i][0] == COUGAR_KEY_G6) {
                        cougar_mapping[i][1] =
                                g6_is_space ? KEY_SPACE : KEY_F18;
                        pr_info("cougar: G6 mapped to %s\n",
                                g6_is_space ? "space" : "F18");
                        return;
                }
        }
        pr_warn("cougar: no mappings defined for G6/spacebar");
}

/*
 * Constant-friendly rdesc fixup for mouse interface
 */
static const __u8 *cougar_report_fixup(struct hid_device *hdev, __u8 *rdesc,
                                       unsigned int *rsize)
{
        if (*rsize >= 117 && rdesc[2] == 0x09 && rdesc[3] == 0x02 &&
            (rdesc[115] | rdesc[116] << 8) >= HID_MAX_USAGES) {
                hid_info(hdev,
                        "usage count exceeds max: fixing up report descriptor\n");
                rdesc[115] = ((HID_MAX_USAGES-1) & 0xff);
                rdesc[116] = ((HID_MAX_USAGES-1) >> 8);
        }
        return rdesc;
}

static struct cougar_shared *cougar_get_shared_data(struct hid_device *hdev)
{
        struct cougar_shared *shared;

        /* Try to find an already-probed interface from the same device */
        list_for_each_entry(shared, &cougar_udev_list, list) {
                if (hid_compare_device_paths(hdev, shared->dev, '/')) {
                        kref_get(&shared->kref);
                        return shared;
                }
        }
        return NULL;
}

static void cougar_release_shared_data(struct kref *kref)
{
        struct cougar_shared *shared = container_of(kref,
                                                    struct cougar_shared, kref);

        mutex_lock(&cougar_udev_list_lock);
        list_del(&shared->list);
        mutex_unlock(&cougar_udev_list_lock);

        kfree(shared);
}

static void cougar_remove_shared_data(void *resource)
{
        struct cougar *cougar = resource;

        if (cougar->shared) {
                kref_put(&cougar->shared->kref, cougar_release_shared_data);
                cougar->shared = NULL;
        }
}

/*
 * Bind the device group's shared data to this cougar struct.
 * If no shared data exists for this group, create and initialize it.
 */
static int cougar_bind_shared_data(struct hid_device *hdev,
                                   struct cougar *cougar)
{
        struct cougar_shared *shared;
        int error = 0;

        mutex_lock(&cougar_udev_list_lock);

        shared = cougar_get_shared_data(hdev);
        if (!shared) {
                shared = kzalloc_obj(*shared);
                if (!shared) {
                        error = -ENOMEM;
                        goto out;
                }

                kref_init(&shared->kref);
                shared->dev = hdev;
                list_add_tail(&shared->list, &cougar_udev_list);
        }

        cougar->shared = shared;

        error = devm_add_action_or_reset(&hdev->dev, cougar_remove_shared_data, cougar);
        if (error) {
                mutex_unlock(&cougar_udev_list_lock);
                return error;
        }

out:
        mutex_unlock(&cougar_udev_list_lock);
        return error;
}

static int cougar_probe(struct hid_device *hdev,
                        const struct hid_device_id *id)
{
        struct cougar *cougar;
        struct hid_input *next, *hidinput = NULL;
        unsigned int connect_mask;
        int error;

        cougar = devm_kzalloc(&hdev->dev, sizeof(*cougar), GFP_KERNEL);
        if (!cougar)
                return -ENOMEM;
        hid_set_drvdata(hdev, cougar);

        error = hid_parse(hdev);
        if (error) {
                hid_err(hdev, "parse failed\n");
                return error;
        }

        if (hdev->collection->usage == COUGAR_VENDOR_USAGE) {
                cougar->special_intf = true;
                connect_mask = HID_CONNECT_HIDRAW;
        } else
                connect_mask = HID_CONNECT_DEFAULT;

        error = hid_hw_start(hdev, connect_mask);
        if (error) {
                hid_err(hdev, "hw start failed\n");
                return error;
        }

        error = cougar_bind_shared_data(hdev, cougar);
        if (error)
                goto fail_stop_and_cleanup;

        /* The custom vendor interface will use the hid_input registered
         * for the keyboard interface, in order to send translated key codes
         * to it.
         */
        if (hdev->collection->usage == HID_GD_KEYBOARD) {
                list_for_each_entry_safe(hidinput, next, &hdev->inputs, list) {
                        if (hidinput->registered && hidinput->input != NULL) {
                                cougar->shared->input = hidinput->input;
                                cougar->shared->enabled = true;
                                break;
                        }
                }
        } else if (hdev->collection->usage == COUGAR_VENDOR_USAGE) {
                /* Preinit the mapping table */
                cougar_fix_g6_mapping();
                error = hid_hw_open(hdev);
                if (error)
                        goto fail_stop_and_cleanup;
        }
        return 0;

fail_stop_and_cleanup:
        hid_hw_stop(hdev);
        return error;
}

/*
 * Convert events from vendor intf to input key events
 */
static int cougar_raw_event(struct hid_device *hdev, struct hid_report *report,
                            u8 *data, int size)
{
        struct cougar *cougar;
        struct cougar_shared *shared;
        unsigned char code, action;
        int i;

        cougar = hid_get_drvdata(hdev);
        shared = cougar->shared;
        if (!cougar->special_intf || !shared)
                return 0;

        if (!shared->enabled || !shared->input)
                return -EPERM;

        code = data[COUGAR_FIELD_CODE];
        action = data[COUGAR_FIELD_ACTION];
        for (i = 0; cougar_mapping[i][0]; i++) {
                if (code == cougar_mapping[i][0]) {
                        input_event(shared->input, EV_KEY,
                                    cougar_mapping[i][1], action);
                        input_sync(shared->input);
                        return -EPERM;
                }
        }
        /* Avoid warnings on the same unmapped key twice */
        if (action != 0)
                hid_warn(hdev, "unmapped special key code %0x: ignoring\n", code);
        return -EPERM;
}

static void cougar_remove(struct hid_device *hdev)
{
        struct cougar *cougar = hid_get_drvdata(hdev);

        if (cougar) {
                /* Stop the vendor intf to process more events */
                if (cougar->shared)
                        cougar->shared->enabled = false;
                if (cougar->special_intf)
                        hid_hw_close(hdev);
        }
        hid_hw_stop(hdev);
}

static int cougar_param_set_g6_is_space(const char *val,
                                        const struct kernel_param *kp)
{
        int ret;

        ret = param_set_bool(val, kp);
        if (ret)
                return ret;

        cougar_fix_g6_mapping();

        return 0;
}

static const struct kernel_param_ops cougar_g6_is_space_ops = {
        .set    = cougar_param_set_g6_is_space,
        .get    = param_get_bool,
};
module_param_cb(g6_is_space, &cougar_g6_is_space_ops, &g6_is_space, 0644);

static const struct hid_device_id cougar_id_table[] = {
        { HID_USB_DEVICE(USB_VENDOR_ID_SOLID_YEAR,
                         USB_DEVICE_ID_COUGAR_500K_GAMING_KEYBOARD) },
        { HID_USB_DEVICE(USB_VENDOR_ID_SOLID_YEAR,
                         USB_DEVICE_ID_COUGAR_700K_GAMING_KEYBOARD) },
        {}
};
MODULE_DEVICE_TABLE(hid, cougar_id_table);

static struct hid_driver cougar_driver = {
        .name                   = "cougar",
        .id_table               = cougar_id_table,
        .report_fixup           = cougar_report_fixup,
        .probe                  = cougar_probe,
        .remove                 = cougar_remove,
        .raw_event              = cougar_raw_event,
};

module_hid_driver(cougar_driver);