/*
 *  HID driver for Logitech Unifying receivers
 *
 *  Copyright (c) 2011 Logitech
 */

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.

 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */


#include <linux/device.h>
#include <linux/hid.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/kfifo.h>
#include <asm/unaligned.h>
#include "hid-ids.h"

#define DJ_MAX_PAIRED_DEVICES                   6
#define DJ_MAX_NUMBER_NOTIFICATIONS             8
#define DJ_RECEIVER_INDEX                       0
#define DJ_DEVICE_INDEX_MIN                     1
#define DJ_DEVICE_INDEX_MAX                     6

#define DJREPORT_SHORT_LENGTH                   15
#define DJREPORT_LONG_LENGTH                    32

#define REPORT_ID_DJ_SHORT                      0x20
#define REPORT_ID_DJ_LONG                       0x21

#define REPORT_ID_HIDPP_SHORT                   0x10
#define REPORT_ID_HIDPP_LONG                    0x11

#define HIDPP_REPORT_SHORT_LENGTH               7
#define HIDPP_REPORT_LONG_LENGTH                20

#define HIDPP_RECEIVER_INDEX                    0xff

#define REPORT_TYPE_RFREPORT_FIRST              0x01
#define REPORT_TYPE_RFREPORT_LAST               0x1F

/* Command Switch to DJ mode */
#define REPORT_TYPE_CMD_SWITCH                  0x80
#define CMD_SWITCH_PARAM_DEVBITFIELD            0x00
#define CMD_SWITCH_PARAM_TIMEOUT_SECONDS        0x01
#define TIMEOUT_NO_KEEPALIVE                    0x00

/* Command to Get the list of Paired devices */
#define REPORT_TYPE_CMD_GET_PAIRED_DEVICES      0x81

/* Device Paired Notification */
#define REPORT_TYPE_NOTIF_DEVICE_PAIRED         0x41
#define SPFUNCTION_MORE_NOTIF_EXPECTED          0x01
#define SPFUNCTION_DEVICE_LIST_EMPTY            0x02
#define DEVICE_PAIRED_PARAM_SPFUNCTION          0x00
#define DEVICE_PAIRED_PARAM_EQUAD_ID_LSB        0x01
#define DEVICE_PAIRED_PARAM_EQUAD_ID_MSB        0x02
#define DEVICE_PAIRED_RF_REPORT_TYPE            0x03

/* Device Un-Paired Notification */
#define REPORT_TYPE_NOTIF_DEVICE_UNPAIRED       0x40


/* Connection Status Notification */
#define REPORT_TYPE_NOTIF_CONNECTION_STATUS     0x42
#define CONNECTION_STATUS_PARAM_STATUS          0x00
#define STATUS_LINKLOSS                         0x01

/* Error Notification */
#define REPORT_TYPE_NOTIF_ERROR                 0x7F
#define NOTIF_ERROR_PARAM_ETYPE                 0x00
#define ETYPE_KEEPALIVE_TIMEOUT                 0x01

/* supported DJ HID && RF report types */
#define REPORT_TYPE_KEYBOARD                    0x01
#define REPORT_TYPE_MOUSE                       0x02
#define REPORT_TYPE_CONSUMER_CONTROL            0x03
#define REPORT_TYPE_SYSTEM_CONTROL              0x04
#define REPORT_TYPE_MEDIA_CENTER                0x08
#define REPORT_TYPE_LEDS                        0x0E

/* RF Report types bitfield */
#define STD_KEYBOARD                            0x00000002
#define STD_MOUSE                               0x00000004
#define MULTIMEDIA                              0x00000008
#define POWER_KEYS                              0x00000010
#define MEDIA_CENTER                            0x00000100
#define KBD_LEDS                                0x00004000

struct dj_report {
        u8 report_id;
        u8 device_index;
        u8 report_type;
        u8 report_params[DJREPORT_SHORT_LENGTH - 3];
};

struct dj_receiver_dev {
        struct hid_device *hdev;
        struct dj_device *paired_dj_devices[DJ_MAX_PAIRED_DEVICES +
                                            DJ_DEVICE_INDEX_MIN];
        struct work_struct work;
        struct kfifo notif_fifo;
        spinlock_t lock;
        bool querying_devices;
};

struct dj_device {
        struct hid_device *hdev;
        struct dj_receiver_dev *dj_receiver_dev;
        u32 reports_supported;
        u8 device_index;
};

/* Keyboard descriptor (1) */
static const char kbd_descriptor[] = {
        0x05, 0x01,             /* USAGE_PAGE (generic Desktop)     */
        0x09, 0x06,             /* USAGE (Keyboard)         */
        0xA1, 0x01,             /* COLLECTION (Application)     */
        0x85, 0x01,             /* REPORT_ID (1)            */
        0x95, 0x08,             /*   REPORT_COUNT (8)           */
        0x75, 0x01,             /*   REPORT_SIZE (1)            */
        0x15, 0x00,             /*   LOGICAL_MINIMUM (0)        */
        0x25, 0x01,             /*   LOGICAL_MAXIMUM (1)        */
        0x05, 0x07,             /*   USAGE_PAGE (Keyboard)      */
        0x19, 0xE0,             /*   USAGE_MINIMUM (Left Control)   */
        0x29, 0xE7,             /*   USAGE_MAXIMUM (Right GUI)      */
        0x81, 0x02,             /*   INPUT (Data,Var,Abs)       */
        0x95, 0x06,             /*   REPORT_COUNT (6)           */
        0x75, 0x08,             /*   REPORT_SIZE (8)            */
        0x15, 0x00,             /*   LOGICAL_MINIMUM (0)        */
        0x26, 0xFF, 0x00,       /*   LOGICAL_MAXIMUM (255)      */
        0x05, 0x07,             /*   USAGE_PAGE (Keyboard)      */
        0x19, 0x00,             /*   USAGE_MINIMUM (no event)       */
        0x2A, 0xFF, 0x00,       /*   USAGE_MAXIMUM (reserved)       */
        0x81, 0x00,             /*   INPUT (Data,Ary,Abs)       */
        0x85, 0x0e,             /* REPORT_ID (14)               */
        0x05, 0x08,             /*   USAGE PAGE (LED page)      */
        0x95, 0x05,             /*   REPORT COUNT (5)           */
        0x75, 0x01,             /*   REPORT SIZE (1)            */
        0x15, 0x00,             /*   LOGICAL_MINIMUM (0)        */
        0x25, 0x01,             /*   LOGICAL_MAXIMUM (1)        */
        0x19, 0x01,             /*   USAGE MINIMUM (1)          */
        0x29, 0x05,             /*   USAGE MAXIMUM (5)          */
        0x91, 0x02,             /*   OUTPUT (Data, Variable, Absolute)  */
        0x95, 0x01,             /*   REPORT COUNT (1)           */
        0x75, 0x03,             /*   REPORT SIZE (3)            */
        0x91, 0x01,             /*   OUTPUT (Constant)          */
        0xC0
};

/* Mouse descriptor (2)     */
static const char mse_descriptor[] = {
        0x05, 0x01,             /*  USAGE_PAGE (Generic Desktop)        */
        0x09, 0x02,             /*  USAGE (Mouse)                       */
        0xA1, 0x01,             /*  COLLECTION (Application)            */
        0x85, 0x02,             /*    REPORT_ID = 2                     */
        0x09, 0x01,             /*    USAGE (pointer)                   */
        0xA1, 0x00,             /*    COLLECTION (physical)             */
        0x05, 0x09,             /*      USAGE_PAGE (buttons)            */
        0x19, 0x01,             /*      USAGE_MIN (1)                   */
        0x29, 0x10,             /*      USAGE_MAX (16)                  */
        0x15, 0x00,             /*      LOGICAL_MIN (0)                 */
        0x25, 0x01,             /*      LOGICAL_MAX (1)                 */
        0x95, 0x10,             /*      REPORT_COUNT (16)               */
        0x75, 0x01,             /*      REPORT_SIZE (1)                 */
        0x81, 0x02,             /*      INPUT (data var abs)            */
        0x05, 0x01,             /*      USAGE_PAGE (generic desktop)    */
        0x16, 0x01, 0xF8,       /*      LOGICAL_MIN (-2047)             */
        0x26, 0xFF, 0x07,       /*      LOGICAL_MAX (2047)              */
        0x75, 0x0C,             /*      REPORT_SIZE (12)                */
        0x95, 0x02,             /*      REPORT_COUNT (2)                */
        0x09, 0x30,             /*      USAGE (X)                       */
        0x09, 0x31,             /*      USAGE (Y)                       */
        0x81, 0x06,             /*      INPUT                           */
        0x15, 0x81,             /*      LOGICAL_MIN (-127)              */
        0x25, 0x7F,             /*      LOGICAL_MAX (127)               */
        0x75, 0x08,             /*      REPORT_SIZE (8)                 */
        0x95, 0x01,             /*      REPORT_COUNT (1)                */
        0x09, 0x38,             /*      USAGE (wheel)                   */
        0x81, 0x06,             /*      INPUT                           */
        0x05, 0x0C,             /*      USAGE_PAGE(consumer)            */
        0x0A, 0x38, 0x02,       /*      USAGE(AC Pan)                   */
        0x95, 0x01,             /*      REPORT_COUNT (1)                */
        0x81, 0x06,             /*      INPUT                           */
        0xC0,                   /*    END_COLLECTION                    */
        0xC0,                   /*  END_COLLECTION                      */
};

/* Consumer Control descriptor (3) */
static const char consumer_descriptor[] = {
        0x05, 0x0C,             /* USAGE_PAGE (Consumer Devices)       */
        0x09, 0x01,             /* USAGE (Consumer Control)            */
        0xA1, 0x01,             /* COLLECTION (Application)            */
        0x85, 0x03,             /* REPORT_ID = 3                       */
        0x75, 0x10,             /* REPORT_SIZE (16)                    */
        0x95, 0x02,             /* REPORT_COUNT (2)                    */
        0x15, 0x01,             /* LOGICAL_MIN (1)                     */
        0x26, 0x8C, 0x02,       /* LOGICAL_MAX (652)                   */
        0x19, 0x01,             /* USAGE_MIN (1)                       */
        0x2A, 0x8C, 0x02,       /* USAGE_MAX (652)                     */
        0x81, 0x00,             /* INPUT (Data Ary Abs)                */
        0xC0,                   /* END_COLLECTION                      */
};                              /*                                     */

/* System control descriptor (4) */
static const char syscontrol_descriptor[] = {
        0x05, 0x01,             /*   USAGE_PAGE (Generic Desktop)      */
        0x09, 0x80,             /*   USAGE (System Control)            */
        0xA1, 0x01,             /*   COLLECTION (Application)          */
        0x85, 0x04,             /*   REPORT_ID = 4                     */
        0x75, 0x02,             /*   REPORT_SIZE (2)                   */
        0x95, 0x01,             /*   REPORT_COUNT (1)                  */
        0x15, 0x01,             /*   LOGICAL_MIN (1)                   */
        0x25, 0x03,             /*   LOGICAL_MAX (3)                   */
        0x09, 0x82,             /*   USAGE (System Sleep)              */
        0x09, 0x81,             /*   USAGE (System Power Down)         */
        0x09, 0x83,             /*   USAGE (System Wake Up)            */
        0x81, 0x60,             /*   INPUT (Data Ary Abs NPrf Null)    */
        0x75, 0x06,             /*   REPORT_SIZE (6)                   */
        0x81, 0x03,             /*   INPUT (Cnst Var Abs)              */
        0xC0,                   /*   END_COLLECTION                    */
};

/* Media descriptor (8) */
static const char media_descriptor[] = {
        0x06, 0xbc, 0xff,       /* Usage Page 0xffbc                   */
        0x09, 0x88,             /* Usage 0x0088                        */
        0xa1, 0x01,             /* BeginCollection                     */
        0x85, 0x08,             /*   Report ID 8                       */
        0x19, 0x01,             /*   Usage Min 0x0001                  */
        0x29, 0xff,             /*   Usage Max 0x00ff                  */
        0x15, 0x01,             /*   Logical Min 1                     */
        0x26, 0xff, 0x00,       /*   Logical Max 255                   */
        0x75, 0x08,             /*   Report Size 8                     */
        0x95, 0x01,             /*   Report Count 1                    */
        0x81, 0x00,             /*   Input                             */
        0xc0,                   /* EndCollection                       */
};                              /*                                     */

/* HIDPP descriptor */
static const char hidpp_descriptor[] = {
        0x06, 0x00, 0xff,       /* Usage Page (Vendor Defined Page 1)  */
        0x09, 0x01,             /* Usage (Vendor Usage 1)              */
        0xa1, 0x01,             /* Collection (Application)            */
        0x85, 0x10,             /*   Report ID (16)                    */
        0x75, 0x08,             /*   Report Size (8)                   */
        0x95, 0x06,             /*   Report Count (6)                  */
        0x15, 0x00,             /*   Logical Minimum (0)               */
        0x26, 0xff, 0x00,       /*   Logical Maximum (255)             */
        0x09, 0x01,             /*   Usage (Vendor Usage 1)            */
        0x81, 0x00,             /*   Input (Data,Arr,Abs)              */
        0x09, 0x01,             /*   Usage (Vendor Usage 1)            */
        0x91, 0x00,             /*   Output (Data,Arr,Abs)             */
        0xc0,                   /* End Collection                      */
        0x06, 0x00, 0xff,       /* Usage Page (Vendor Defined Page 1)  */
        0x09, 0x02,             /* Usage (Vendor Usage 2)              */
        0xa1, 0x01,             /* Collection (Application)            */
        0x85, 0x11,             /*   Report ID (17)                    */
        0x75, 0x08,             /*   Report Size (8)                   */
        0x95, 0x13,             /*   Report Count (19)                 */
        0x15, 0x00,             /*   Logical Minimum (0)               */
        0x26, 0xff, 0x00,       /*   Logical Maximum (255)             */
        0x09, 0x02,             /*   Usage (Vendor Usage 2)            */
        0x81, 0x00,             /*   Input (Data,Arr,Abs)              */
        0x09, 0x02,             /*   Usage (Vendor Usage 2)            */
        0x91, 0x00,             /*   Output (Data,Arr,Abs)             */
        0xc0,                   /* End Collection                      */
        0x06, 0x00, 0xff,       /* Usage Page (Vendor Defined Page 1)  */
        0x09, 0x04,             /* Usage (Vendor Usage 0x04)           */
        0xa1, 0x01,             /* Collection (Application)            */
        0x85, 0x20,             /*   Report ID (32)                    */
        0x75, 0x08,             /*   Report Size (8)                   */
        0x95, 0x0e,             /*   Report Count (14)                 */
        0x15, 0x00,             /*   Logical Minimum (0)               */
        0x26, 0xff, 0x00,       /*   Logical Maximum (255)             */
        0x09, 0x41,             /*   Usage (Vendor Usage 0x41)         */
        0x81, 0x00,             /*   Input (Data,Arr,Abs)              */
        0x09, 0x41,             /*   Usage (Vendor Usage 0x41)         */
        0x91, 0x00,             /*   Output (Data,Arr,Abs)             */
        0x85, 0x21,             /*   Report ID (33)                    */
        0x95, 0x1f,             /*   Report Count (31)                 */
        0x15, 0x00,             /*   Logical Minimum (0)               */
        0x26, 0xff, 0x00,       /*   Logical Maximum (255)             */
        0x09, 0x42,             /*   Usage (Vendor Usage 0x42)         */
        0x81, 0x00,             /*   Input (Data,Arr,Abs)              */
        0x09, 0x42,             /*   Usage (Vendor Usage 0x42)         */
        0x91, 0x00,             /*   Output (Data,Arr,Abs)             */
        0xc0,                   /* End Collection                      */
};

/* Maximum size of all defined hid reports in bytes (including report id) */
#define MAX_REPORT_SIZE 8

/* Make sure all descriptors are present here */
#define MAX_RDESC_SIZE                          \
        (sizeof(kbd_descriptor) +               \
         sizeof(mse_descriptor) +               \
         sizeof(consumer_descriptor) +          \
         sizeof(syscontrol_descriptor) +        \
         sizeof(media_descriptor) +     \
         sizeof(hidpp_descriptor))

/* Number of possible hid report types that can be created by this driver.
 *
 * Right now, RF report types have the same report types (or report id's)
 * than the hid report created from those RF reports. In the future
 * this doesnt have to be true.
 *
 * For instance, RF report type 0x01 which has a size of 8 bytes, corresponds
 * to hid report id 0x01, this is standard keyboard. Same thing applies to mice
 * reports and consumer control, etc. If a new RF report is created, it doesn't
 * has to have the same report id as its corresponding hid report, so an
 * translation may have to take place for future report types.
 */
#define NUMBER_OF_HID_REPORTS 32
static const u8 hid_reportid_size_map[NUMBER_OF_HID_REPORTS] = {
        [1] = 8,                /* Standard keyboard */
        [2] = 8,                /* Standard mouse */
        [3] = 5,                /* Consumer control */
        [4] = 2,                /* System control */
        [8] = 2,                /* Media Center */
};


#define LOGITECH_DJ_INTERFACE_NUMBER 0x02

static struct hid_ll_driver logi_dj_ll_driver;

static int logi_dj_recv_query_paired_devices(struct dj_receiver_dev *djrcv_dev);

static void logi_dj_recv_destroy_djhid_device(struct dj_receiver_dev *djrcv_dev,
                                                struct dj_report *dj_report)
{
        /* Called in delayed work context */
        struct dj_device *dj_dev;
        unsigned long flags;

        spin_lock_irqsave(&djrcv_dev->lock, flags);
        dj_dev = djrcv_dev->paired_dj_devices[dj_report->device_index];
        djrcv_dev->paired_dj_devices[dj_report->device_index] = NULL;
        spin_unlock_irqrestore(&djrcv_dev->lock, flags);

        if (dj_dev != NULL) {
                hid_destroy_device(dj_dev->hdev);
                kfree(dj_dev);
        } else {
                dev_err(&djrcv_dev->hdev->dev, "%s: can't destroy a NULL device\n",
                        __func__);
        }
}

static void logi_dj_recv_add_djhid_device(struct dj_receiver_dev *djrcv_dev,
                                          struct dj_report *dj_report)
{
        /* Called in delayed work context */
        struct hid_device *djrcv_hdev = djrcv_dev->hdev;
        struct usb_interface *intf = to_usb_interface(djrcv_hdev->dev.parent);
        struct usb_device *usbdev = interface_to_usbdev(intf);
        struct hid_device *dj_hiddev;
        struct dj_device *dj_dev;

        /* Device index goes from 1 to 6, we need 3 bytes to store the
         * semicolon, the index, and a null terminator
         */
        unsigned char tmpstr[3];

        if (dj_report->report_params[DEVICE_PAIRED_PARAM_SPFUNCTION] &
            SPFUNCTION_DEVICE_LIST_EMPTY) {
                dbg_hid("%s: device list is empty\n", __func__);
                djrcv_dev->querying_devices = false;
                return;
        }

        if (djrcv_dev->paired_dj_devices[dj_report->device_index]) {
                /* The device is already known. No need to reallocate it. */
                dbg_hid("%s: device is already known\n", __func__);
                return;
        }

        dj_hiddev = hid_allocate_device();
        if (IS_ERR(dj_hiddev)) {
                dev_err(&djrcv_hdev->dev, "%s: hid_allocate_device failed\n",
                        __func__);
                return;
        }

        dj_hiddev->ll_driver = &logi_dj_ll_driver;

        dj_hiddev->dev.parent = &djrcv_hdev->dev;
        dj_hiddev->bus = BUS_USB;
        dj_hiddev->vendor = le16_to_cpu(usbdev->descriptor.idVendor);
        dj_hiddev->product =
                (dj_report->report_params[DEVICE_PAIRED_PARAM_EQUAD_ID_MSB]
                                                                        << 8) |
                dj_report->report_params[DEVICE_PAIRED_PARAM_EQUAD_ID_LSB];
        snprintf(dj_hiddev->name, sizeof(dj_hiddev->name),
                "Logitech Unifying Device. Wireless PID:%04x",
                dj_hiddev->product);

        dj_hiddev->group = HID_GROUP_LOGITECH_DJ_DEVICE;

        usb_make_path(usbdev, dj_hiddev->phys, sizeof(dj_hiddev->phys));
        snprintf(tmpstr, sizeof(tmpstr), ":%d", dj_report->device_index);
        strlcat(dj_hiddev->phys, tmpstr, sizeof(dj_hiddev->phys));

        dj_dev = kzalloc(sizeof(struct dj_device), GFP_KERNEL);

        if (!dj_dev) {
                dev_err(&djrcv_hdev->dev, "%s: failed allocating dj_device\n",
                        __func__);
                goto dj_device_allocate_fail;
        }

        dj_dev->reports_supported = get_unaligned_le32(
                dj_report->report_params + DEVICE_PAIRED_RF_REPORT_TYPE);
        dj_dev->hdev = dj_hiddev;
        dj_dev->dj_receiver_dev = djrcv_dev;
        dj_dev->device_index = dj_report->device_index;
        dj_hiddev->driver_data = dj_dev;

        djrcv_dev->paired_dj_devices[dj_report->device_index] = dj_dev;

        if (hid_add_device(dj_hiddev)) {
                dev_err(&djrcv_hdev->dev, "%s: failed adding dj_device\n",
                        __func__);
                goto hid_add_device_fail;
        }

        return;

hid_add_device_fail:
        djrcv_dev->paired_dj_devices[dj_report->device_index] = NULL;
        kfree(dj_dev);
dj_device_allocate_fail:
        hid_destroy_device(dj_hiddev);
}

static void delayedwork_callback(struct work_struct *work)
{
        struct dj_receiver_dev *djrcv_dev =
                container_of(work, struct dj_receiver_dev, work);

        struct dj_report dj_report;
        unsigned long flags;
        int count;
        int retval;

        dbg_hid("%s\n", __func__);

        spin_lock_irqsave(&djrcv_dev->lock, flags);

        count = kfifo_out(&djrcv_dev->notif_fifo, &dj_report,
                                sizeof(struct dj_report));

        if (count != sizeof(struct dj_report)) {
                dev_err(&djrcv_dev->hdev->dev, "%s: workitem triggered without "
                        "notifications available\n", __func__);
                spin_unlock_irqrestore(&djrcv_dev->lock, flags);
                return;
        }

        if (!kfifo_is_empty(&djrcv_dev->notif_fifo)) {
                if (schedule_work(&djrcv_dev->work) == 0) {
                        dbg_hid("%s: did not schedule the work item, was "
                                "already queued\n", __func__);
                }
        }

        spin_unlock_irqrestore(&djrcv_dev->lock, flags);

        switch (dj_report.report_type) {
        case REPORT_TYPE_NOTIF_DEVICE_PAIRED:
                logi_dj_recv_add_djhid_device(djrcv_dev, &dj_report);
                break;
        case REPORT_TYPE_NOTIF_DEVICE_UNPAIRED:
                logi_dj_recv_destroy_djhid_device(djrcv_dev, &dj_report);
                break;
        default:
        /* A normal report (i. e. not belonging to a pair/unpair notification)
         * arriving here, means that the report arrived but we did not have a
         * paired dj_device associated to the report's device_index, this
         * means that the original "device paired" notification corresponding
         * to this dj_device never arrived to this driver. The reason is that
         * hid-core discards all packets coming from a device while probe() is
         * executing. */
        if (!djrcv_dev->paired_dj_devices[dj_report.device_index]) {
                /* ok, we don't know the device, just re-ask the
                 * receiver for the list of connected devices. */
                retval = logi_dj_recv_query_paired_devices(djrcv_dev);
                if (!retval) {
                        /* everything went fine, so just leave */
                        break;
                }
                dev_err(&djrcv_dev->hdev->dev,
                        "%s:logi_dj_recv_query_paired_devices "
                        "error:%d\n", __func__, retval);
                }
                dbg_hid("%s: unexpected report type\n", __func__);
        }
}

static void logi_dj_recv_queue_notification(struct dj_receiver_dev *djrcv_dev,
                                           struct dj_report *dj_report)
{
        /* We are called from atomic context (tasklet && djrcv->lock held) */

        kfifo_in(&djrcv_dev->notif_fifo, dj_report, sizeof(struct dj_report));

        if (schedule_work(&djrcv_dev->work) == 0) {
                dbg_hid("%s: did not schedule the work item, was already "
                        "queued\n", __func__);
        }
}

static void logi_dj_recv_forward_null_report(struct dj_receiver_dev *djrcv_dev,
                                             struct dj_report *dj_report)
{
        /* We are called from atomic context (tasklet && djrcv->lock held) */
        unsigned int i;
        u8 reportbuffer[MAX_REPORT_SIZE];
        struct dj_device *djdev;

        djdev = djrcv_dev->paired_dj_devices[dj_report->device_index];

        memset(reportbuffer, 0, sizeof(reportbuffer));

        for (i = 0; i < NUMBER_OF_HID_REPORTS; i++) {
                if (djdev->reports_supported & (1 << i)) {
                        reportbuffer[0] = i;
                        if (hid_input_report(djdev->hdev,
                                             HID_INPUT_REPORT,
                                             reportbuffer,
                                             hid_reportid_size_map[i], 1)) {
                                dbg_hid("hid_input_report error sending null "
                                        "report\n");
                        }
                }
        }
}

static void logi_dj_recv_forward_report(struct dj_receiver_dev *djrcv_dev,
                                        struct dj_report *dj_report)
{
        /* We are called from atomic context (tasklet && djrcv->lock held) */
        struct dj_device *dj_device;

        dj_device = djrcv_dev->paired_dj_devices[dj_report->device_index];

        if ((dj_report->report_type > ARRAY_SIZE(hid_reportid_size_map) - 1) ||
            (hid_reportid_size_map[dj_report->report_type] == 0)) {
                dbg_hid("invalid report type:%x\n", dj_report->report_type);
                return;
        }

        if (hid_input_report(dj_device->hdev,
                        HID_INPUT_REPORT, &dj_report->report_type,
                        hid_reportid_size_map[dj_report->report_type], 1)) {
                dbg_hid("hid_input_report error\n");
        }
}

static void logi_dj_recv_forward_hidpp(struct dj_device *dj_dev, u8 *data,
                                       int size)
{
        /* We are called from atomic context (tasklet && djrcv->lock held) */
        if (hid_input_report(dj_dev->hdev, HID_INPUT_REPORT, data, size, 1))
                dbg_hid("hid_input_report error\n");
}

static int logi_dj_recv_send_report(struct dj_receiver_dev *djrcv_dev,
                                    struct dj_report *dj_report)
{
        struct hid_device *hdev = djrcv_dev->hdev;
        struct hid_report *report;
        struct hid_report_enum *output_report_enum;
        u8 *data = (u8 *)(&dj_report->device_index);
        unsigned int i;

        output_report_enum = &hdev->report_enum[HID_OUTPUT_REPORT];
        report = output_report_enum->report_id_hash[REPORT_ID_DJ_SHORT];

        if (!report) {
                dev_err(&hdev->dev, "%s: unable to find dj report\n", __func__);
                return -ENODEV;
        }

        for (i = 0; i < DJREPORT_SHORT_LENGTH - 1; i++)
                report->field[0]->value[i] = data[i];

        hid_hw_request(hdev, report, HID_REQ_SET_REPORT);

        return 0;
}

static int logi_dj_recv_query_paired_devices(struct dj_receiver_dev *djrcv_dev)
{
        struct dj_report *dj_report;
        int retval;

        /* no need to protect djrcv_dev->querying_devices */
        if (djrcv_dev->querying_devices)
                return 0;

        dj_report = kzalloc(sizeof(struct dj_report), GFP_KERNEL);
        if (!dj_report)
                return -ENOMEM;
        dj_report->report_id = REPORT_ID_DJ_SHORT;
        dj_report->device_index = 0xFF;
        dj_report->report_type = REPORT_TYPE_CMD_GET_PAIRED_DEVICES;
        retval = logi_dj_recv_send_report(djrcv_dev, dj_report);
        kfree(dj_report);
        return retval;
}


static int logi_dj_recv_switch_to_dj_mode(struct dj_receiver_dev *djrcv_dev,
                                          unsigned timeout)
{
        struct hid_device *hdev = djrcv_dev->hdev;
        struct dj_report *dj_report;
        u8 *buf;
        int retval;

        dj_report = kzalloc(sizeof(struct dj_report), GFP_KERNEL);
        if (!dj_report)
                return -ENOMEM;
        dj_report->report_id = REPORT_ID_DJ_SHORT;
        dj_report->device_index = 0xFF;
        dj_report->report_type = REPORT_TYPE_CMD_SWITCH;
        dj_report->report_params[CMD_SWITCH_PARAM_DEVBITFIELD] = 0x3F;
        dj_report->report_params[CMD_SWITCH_PARAM_TIMEOUT_SECONDS] = (u8)timeout;
        retval = logi_dj_recv_send_report(djrcv_dev, dj_report);

        /*
         * Ugly sleep to work around a USB 3.0 bug when the receiver is still
         * processing the "switch-to-dj" command while we send an other command.
         * 50 msec should gives enough time to the receiver to be ready.
         */
        msleep(50);

        /*
         * Magical bits to set up hidpp notifications when the dj devices
         * are connected/disconnected.
         *
         * We can reuse dj_report because HIDPP_REPORT_SHORT_LENGTH is smaller
         * than DJREPORT_SHORT_LENGTH.
         */
        buf = (u8 *)dj_report;

        memset(buf, 0, HIDPP_REPORT_SHORT_LENGTH);

        buf[0] = REPORT_ID_HIDPP_SHORT;
        buf[1] = 0xFF;
        buf[2] = 0x80;
        buf[3] = 0x00;
        buf[4] = 0x00;
        buf[5] = 0x09;
        buf[6] = 0x00;

        hid_hw_raw_request(hdev, REPORT_ID_HIDPP_SHORT, buf,
                        HIDPP_REPORT_SHORT_LENGTH, HID_OUTPUT_REPORT,
                        HID_REQ_SET_REPORT);

        kfree(dj_report);
        return retval;
}


static int logi_dj_ll_open(struct hid_device *hid)
{
        dbg_hid("%s:%s\n", __func__, hid->phys);
        return 0;

}

static void logi_dj_ll_close(struct hid_device *hid)
{
        dbg_hid("%s:%s\n", __func__, hid->phys);
}

/*
 * Register 0xB5 is "pairing information". It is solely intended for the
 * receiver, so do not overwrite the device index.
 */
static u8 unifying_pairing_query[]  = {0x10, 0xff, 0x83, 0xb5};
static u8 unifying_pairing_answer[] = {0x11, 0xff, 0x83, 0xb5};

static int logi_dj_ll_raw_request(struct hid_device *hid,
                                  unsigned char reportnum, __u8 *buf,
                                  size_t count, unsigned char report_type,
                                  int reqtype)
{
        struct dj_device *djdev = hid->driver_data;
        struct dj_receiver_dev *djrcv_dev = djdev->dj_receiver_dev;
        u8 *out_buf;
        int ret;

        if ((buf[0] == REPORT_ID_HIDPP_SHORT) ||
            (buf[0] == REPORT_ID_HIDPP_LONG)) {
                if (count < 2)
                        return -EINVAL;

                /* special case where we should not overwrite
                 * the device_index */
                if (count == 7 && !memcmp(buf, unifying_pairing_query,
                                          sizeof(unifying_pairing_query)))
                        buf[4] = (buf[4] & 0xf0) | (djdev->device_index - 1);
                else
                        buf[1] = djdev->device_index;
                return hid_hw_raw_request(djrcv_dev->hdev, reportnum, buf,
                                count, report_type, reqtype);
        }

        if (buf[0] != REPORT_TYPE_LEDS)
                return -EINVAL;

        out_buf = kzalloc(DJREPORT_SHORT_LENGTH, GFP_ATOMIC);
        if (!out_buf)
                return -ENOMEM;

        if (count > DJREPORT_SHORT_LENGTH - 2)
                count = DJREPORT_SHORT_LENGTH - 2;

        out_buf[0] = REPORT_ID_DJ_SHORT;
        out_buf[1] = djdev->device_index;
        memcpy(out_buf + 2, buf, count);

        ret = hid_hw_raw_request(djrcv_dev->hdev, out_buf[0], out_buf,
                DJREPORT_SHORT_LENGTH, report_type, reqtype);

        kfree(out_buf);
        return ret;
}

static void rdcat(char *rdesc, unsigned int *rsize, const char *data, unsigned int size)
{
        memcpy(rdesc + *rsize, data, size);
        *rsize += size;
}

static int logi_dj_ll_parse(struct hid_device *hid)
{
        struct dj_device *djdev = hid->driver_data;
        unsigned int rsize = 0;
        char *rdesc;
        int retval;

        dbg_hid("%s\n", __func__);

        djdev->hdev->version = 0x0111;
        djdev->hdev->country = 0x00;

        rdesc = kmalloc(MAX_RDESC_SIZE, GFP_KERNEL);
        if (!rdesc)
                return -ENOMEM;

        if (djdev->reports_supported & STD_KEYBOARD) {
                dbg_hid("%s: sending a kbd descriptor, reports_supported: %x\n",
                        __func__, djdev->reports_supported);
                rdcat(rdesc, &rsize, kbd_descriptor, sizeof(kbd_descriptor));
        }

        if (djdev->reports_supported & STD_MOUSE) {
                dbg_hid("%s: sending a mouse descriptor, reports_supported: "
                        "%x\n", __func__, djdev->reports_supported);
                rdcat(rdesc, &rsize, mse_descriptor, sizeof(mse_descriptor));
        }

        if (djdev->reports_supported & MULTIMEDIA) {
                dbg_hid("%s: sending a multimedia report descriptor: %x\n",
                        __func__, djdev->reports_supported);
                rdcat(rdesc, &rsize, consumer_descriptor, sizeof(consumer_descriptor));
        }

        if (djdev->reports_supported & POWER_KEYS) {
                dbg_hid("%s: sending a power keys report descriptor: %x\n",
                        __func__, djdev->reports_supported);
                rdcat(rdesc, &rsize, syscontrol_descriptor, sizeof(syscontrol_descriptor));
        }

        if (djdev->reports_supported & MEDIA_CENTER) {
                dbg_hid("%s: sending a media center report descriptor: %x\n",
                        __func__, djdev->reports_supported);
                rdcat(rdesc, &rsize, media_descriptor, sizeof(media_descriptor));
        }

        if (djdev->reports_supported & KBD_LEDS) {
                dbg_hid("%s: need to send kbd leds report descriptor: %x\n",
                        __func__, djdev->reports_supported);
        }

        rdcat(rdesc, &rsize, hidpp_descriptor, sizeof(hidpp_descriptor));

        retval = hid_parse_report(hid, rdesc, rsize);
        kfree(rdesc);

        return retval;
}

static int logi_dj_ll_start(struct hid_device *hid)
{
        dbg_hid("%s\n", __func__);
        return 0;
}

static void logi_dj_ll_stop(struct hid_device *hid)
{
        dbg_hid("%s\n", __func__);
}


static struct hid_ll_driver logi_dj_ll_driver = {
        .parse = logi_dj_ll_parse,
        .start = logi_dj_ll_start,
        .stop = logi_dj_ll_stop,
        .open = logi_dj_ll_open,
        .close = logi_dj_ll_close,
        .raw_request = logi_dj_ll_raw_request,
};

static int logi_dj_dj_event(struct hid_device *hdev,
                             struct hid_report *report, u8 *data,
                             int size)
{
        struct dj_receiver_dev *djrcv_dev = hid_get_drvdata(hdev);
        struct dj_report *dj_report = (struct dj_report *) data;
        unsigned long flags;

        /*
         * Here we receive all data coming from iface 2, there are 3 cases:
         *
         * 1) Data is intended for this driver i. e. data contains arrival,
         * departure, etc notifications, in which case we queue them for delayed
         * processing by the work queue. We return 1 to hid-core as no further
         * processing is required from it.
         *
         * 2) Data informs a connection change, if the change means rf link
         * loss, then we must send a null report to the upper layer to discard
         * potentially pressed keys that may be repeated forever by the input
         * layer. Return 1 to hid-core as no further processing is required.
         *
         * 3) Data is an actual input event from a paired DJ device in which
         * case we forward it to the correct hid device (via hid_input_report()
         * ) and return 1 so hid-core does not anything else with it.
         */

        if ((dj_report->device_index < DJ_DEVICE_INDEX_MIN) ||
            (dj_report->device_index > DJ_DEVICE_INDEX_MAX)) {
                /*
                 * Device index is wrong, bail out.
                 * This driver can ignore safely the receiver notifications,
                 * so ignore those reports too.
                 */
                if (dj_report->device_index != DJ_RECEIVER_INDEX)
                        dev_err(&hdev->dev, "%s: invalid device index:%d\n",
                                __func__, dj_report->device_index);
                return false;
        }

        spin_lock_irqsave(&djrcv_dev->lock, flags);

        if (!djrcv_dev->paired_dj_devices[dj_report->device_index]) {
                /* received an event for an unknown device, bail out */
                logi_dj_recv_queue_notification(djrcv_dev, dj_report);
                goto out;
        }

        switch (dj_report->report_type) {
        case REPORT_TYPE_NOTIF_DEVICE_PAIRED:
                /* pairing notifications are handled above the switch */
                break;
        case REPORT_TYPE_NOTIF_DEVICE_UNPAIRED:
                logi_dj_recv_queue_notification(djrcv_dev, dj_report);
                break;
        case REPORT_TYPE_NOTIF_CONNECTION_STATUS:
                if (dj_report->report_params[CONNECTION_STATUS_PARAM_STATUS] ==
                    STATUS_LINKLOSS) {
                        logi_dj_recv_forward_null_report(djrcv_dev, dj_report);
                }
                break;
        default:
                logi_dj_recv_forward_report(djrcv_dev, dj_report);
        }

out:
        spin_unlock_irqrestore(&djrcv_dev->lock, flags);

        return true;
}

static int logi_dj_hidpp_event(struct hid_device *hdev,
                             struct hid_report *report, u8 *data,
                             int size)
{
        struct dj_receiver_dev *djrcv_dev = hid_get_drvdata(hdev);
        struct dj_report *dj_report = (struct dj_report *) data;
        unsigned long flags;
        u8 device_index = dj_report->device_index;

        if (device_index == HIDPP_RECEIVER_INDEX) {
                /* special case were the device wants to know its unifying
                 * name */
                if (size == HIDPP_REPORT_LONG_LENGTH &&
                    !memcmp(data, unifying_pairing_answer,
                            sizeof(unifying_pairing_answer)))
                        device_index = (data[4] & 0x0F) + 1;
                else
                        return false;
        }

        /*
         * Data is from the HID++ collection, in this case, we forward the
         * data to the corresponding child dj device and return 0 to hid-core
         * so he data also goes to the hidraw device of the receiver. This
         * allows a user space application to implement the full HID++ routing
         * via the receiver.
         */

        if ((device_index < DJ_DEVICE_INDEX_MIN) ||
            (device_index > DJ_DEVICE_INDEX_MAX)) {
                /*
                 * Device index is wrong, bail out.
                 * This driver can ignore safely the receiver notifications,
                 * so ignore those reports too.
                 */
                dev_err(&hdev->dev, "%s: invalid device index:%d\n",
                                __func__, dj_report->device_index);
                return false;
        }

        spin_lock_irqsave(&djrcv_dev->lock, flags);

        if (!djrcv_dev->paired_dj_devices[device_index])
                /* received an event for an unknown device, bail out */
                goto out;

        logi_dj_recv_forward_hidpp(djrcv_dev->paired_dj_devices[device_index],
                                   data, size);

out:
        spin_unlock_irqrestore(&djrcv_dev->lock, flags);

        return false;
}

static int logi_dj_raw_event(struct hid_device *hdev,
                             struct hid_report *report, u8 *data,
                             int size)
{
        dbg_hid("%s, size:%d\n", __func__, size);

        switch (data[0]) {
        case REPORT_ID_DJ_SHORT:
                if (size != DJREPORT_SHORT_LENGTH) {
                        dev_err(&hdev->dev, "DJ report of bad size (%d)", size);
                        return false;
                }
                return logi_dj_dj_event(hdev, report, data, size);
        case REPORT_ID_HIDPP_SHORT:
                if (size != HIDPP_REPORT_SHORT_LENGTH) {
                        dev_err(&hdev->dev,
                                "Short HID++ report of bad size (%d)", size);
                        return false;
                }
                return logi_dj_hidpp_event(hdev, report, data, size);
        case REPORT_ID_HIDPP_LONG:
                if (size != HIDPP_REPORT_LONG_LENGTH) {
                        dev_err(&hdev->dev,
                                "Long HID++ report of bad size (%d)", size);
                        return false;
                }
                return logi_dj_hidpp_event(hdev, report, data, size);
        }

        return false;
}

static int logi_dj_probe(struct hid_device *hdev,
                         const struct hid_device_id *id)
{
        struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
        struct dj_receiver_dev *djrcv_dev;
        int retval;

        dbg_hid("%s called for ifnum %d\n", __func__,
                intf->cur_altsetting->desc.bInterfaceNumber);

        /* Ignore interfaces 0 and 1, they will not carry any data, dont create
         * any hid_device for them */
        if (intf->cur_altsetting->desc.bInterfaceNumber !=
            LOGITECH_DJ_INTERFACE_NUMBER) {
                dbg_hid("%s: ignoring ifnum %d\n", __func__,
                        intf->cur_altsetting->desc.bInterfaceNumber);
                return -ENODEV;
        }

        /* Treat interface 2 */

        djrcv_dev = kzalloc(sizeof(struct dj_receiver_dev), GFP_KERNEL);
        if (!djrcv_dev) {
                dev_err(&hdev->dev,
                        "%s:failed allocating dj_receiver_dev\n", __func__);
                return -ENOMEM;
        }
        djrcv_dev->hdev = hdev;
        INIT_WORK(&djrcv_dev->work, delayedwork_callback);
        spin_lock_init(&djrcv_dev->lock);
        if (kfifo_alloc(&djrcv_dev->notif_fifo,
                        DJ_MAX_NUMBER_NOTIFICATIONS * sizeof(struct dj_report),
                        GFP_KERNEL)) {
                dev_err(&hdev->dev,
                        "%s:failed allocating notif_fifo\n", __func__);
                kfree(djrcv_dev);
                return -ENOMEM;
        }
        hid_set_drvdata(hdev, djrcv_dev);

        /* Call  to usbhid to fetch the HID descriptors of interface 2 and
         * subsequently call to the hid/hid-core to parse the fetched
         * descriptors, this will in turn create the hidraw and hiddev nodes
         * for interface 2 of the receiver */
        retval = hid_parse(hdev);
        if (retval) {
                dev_err(&hdev->dev,
                        "%s:parse of interface 2 failed\n", __func__);
                goto hid_parse_fail;
        }

        if (!hid_validate_values(hdev, HID_OUTPUT_REPORT, REPORT_ID_DJ_SHORT,
                                 0, DJREPORT_SHORT_LENGTH - 1)) {
                retval = -ENODEV;
                goto hid_parse_fail;
        }

        /* Starts the usb device and connects to upper interfaces hiddev and
         * hidraw */
        retval = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
        if (retval) {
                dev_err(&hdev->dev,
                        "%s:hid_hw_start returned error\n", __func__);
                goto hid_hw_start_fail;
        }

        retval = logi_dj_recv_switch_to_dj_mode(djrcv_dev, 0);
        if (retval < 0) {
                dev_err(&hdev->dev,
                        "%s:logi_dj_recv_switch_to_dj_mode returned error:%d\n",
                        __func__, retval);
                goto switch_to_dj_mode_fail;
        }

        /* This is enabling the polling urb on the IN endpoint */
        retval = hid_hw_open(hdev);
        if (retval < 0) {
                dev_err(&hdev->dev, "%s:hid_hw_open returned error:%d\n",
                        __func__, retval);
                goto llopen_failed;
        }

        /* Allow incoming packets to arrive: */
        hid_device_io_start(hdev);

        retval = logi_dj_recv_query_paired_devices(djrcv_dev);
        if (retval < 0) {
                dev_err(&hdev->dev, "%s:logi_dj_recv_query_paired_devices "
                        "error:%d\n", __func__, retval);
                goto logi_dj_recv_query_paired_devices_failed;
        }

        return retval;

logi_dj_recv_query_paired_devices_failed:
        hid_hw_close(hdev);

llopen_failed:
switch_to_dj_mode_fail:
        hid_hw_stop(hdev);

hid_hw_start_fail:
hid_parse_fail:
        kfifo_free(&djrcv_dev->notif_fifo);
        kfree(djrcv_dev);
        hid_set_drvdata(hdev, NULL);
        return retval;

}

#ifdef CONFIG_PM
static int logi_dj_reset_resume(struct hid_device *hdev)
{
        int retval;
        struct dj_receiver_dev *djrcv_dev = hid_get_drvdata(hdev);

        retval = logi_dj_recv_switch_to_dj_mode(djrcv_dev, 0);
        if (retval < 0) {
                dev_err(&hdev->dev,
                        "%s:logi_dj_recv_switch_to_dj_mode returned error:%d\n",
                        __func__, retval);
        }

        return 0;
}
#endif

static void logi_dj_remove(struct hid_device *hdev)
{
        struct dj_receiver_dev *djrcv_dev = hid_get_drvdata(hdev);
        struct dj_device *dj_dev;
        int i;

        dbg_hid("%s\n", __func__);

        cancel_work_sync(&djrcv_dev->work);

        hid_hw_close(hdev);
        hid_hw_stop(hdev);

        /* I suppose that at this point the only context that can access
         * the djrecv_data is this thread as the work item is guaranteed to
         * have finished and no more raw_event callbacks should arrive after
         * the remove callback was triggered so no locks are put around the
         * code below */
        for (i = 0; i < (DJ_MAX_PAIRED_DEVICES + DJ_DEVICE_INDEX_MIN); i++) {
                dj_dev = djrcv_dev->paired_dj_devices[i];
                if (dj_dev != NULL) {
                        hid_destroy_device(dj_dev->hdev);
                        kfree(dj_dev);
                        djrcv_dev->paired_dj_devices[i] = NULL;
                }
        }

        kfifo_free(&djrcv_dev->notif_fifo);
        kfree(djrcv_dev);
        hid_set_drvdata(hdev, NULL);
}

static const struct hid_device_id logi_dj_receivers[] = {
        {HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH,
                USB_DEVICE_ID_LOGITECH_UNIFYING_RECEIVER)},
        {HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH,
                USB_DEVICE_ID_LOGITECH_UNIFYING_RECEIVER_2)},
        {}
};

MODULE_DEVICE_TABLE(hid, logi_dj_receivers);

static struct hid_driver logi_djreceiver_driver = {
        .name = "logitech-djreceiver",
        .id_table = logi_dj_receivers,
        .probe = logi_dj_probe,
        .remove = logi_dj_remove,
        .raw_event = logi_dj_raw_event,
#ifdef CONFIG_PM
        .reset_resume = logi_dj_reset_resume,
#endif
};

module_hid_driver(logi_djreceiver_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Logitech");
MODULE_AUTHOR("Nestor Lopez Casado");
MODULE_AUTHOR("nlopezcasad@logitech.com");