// 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
  ",
  				g6_is_space ? "space" : "F18");

  			return;
  		}
  	}

  	pr_warn("cougar: no mappings defined for G6/spacebar");

  }
  
  /*
   * Constant-friendly rdesc fixup for mouse interface
   */
  static __u8 *cougar_report_fixup(struct hid_device *hdev, __u8 *rdesc,
  				 unsigned int *rsize)
  {
  	if (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
  ");
  		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(sizeof(*shared), GFP_KERNEL);
  		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(&hdev->dev, cougar_remove_shared_data, cougar);
  	if (error) {
  		mutex_unlock(&cougar_udev_list_lock);
  		cougar_remove_shared_data(cougar);
  		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
  ");

  		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
  ");

  		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
  ", 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);