/*
 * Copyright (c) 2012 Hans Verkuil <hverkuil@xs4all.nl>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 */

/* kernel includes */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/videodev2.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-ctrls.h>
#include <media/v4l2-event.h>
#include <linux/usb.h>
#include <linux/mutex.h>

/* driver and module definitions */
MODULE_AUTHOR("Hans Verkuil <hverkuil@xs4all.nl>");
MODULE_DESCRIPTION("Keene FM Transmitter driver");
MODULE_LICENSE("GPL");

/* Actually, it advertises itself as a Logitech */
#define USB_KEENE_VENDOR 0x046d
#define USB_KEENE_PRODUCT 0x0a0e

/* Probably USB_TIMEOUT should be modified in module parameter */
#define BUFFER_LENGTH 8
#define USB_TIMEOUT 500

/* Frequency limits in MHz */
#define FREQ_MIN  76U
#define FREQ_MAX 108U
#define FREQ_MUL 16000U

/* USB Device ID List */
static const struct usb_device_id usb_keene_device_table[] = {
        {USB_DEVICE_AND_INTERFACE_INFO(USB_KEENE_VENDOR, USB_KEENE_PRODUCT,
                                                        USB_CLASS_HID, 0, 0) },
        { }                                             /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, usb_keene_device_table);

struct keene_device {
        struct usb_device *usbdev;
        struct usb_interface *intf;
        struct video_device vdev;
        struct v4l2_device v4l2_dev;
        struct v4l2_ctrl_handler hdl;
        struct mutex lock;

        u8 *buffer;
        unsigned curfreq;
        u8 tx;
        u8 pa;
        bool stereo;
        bool muted;
        bool preemph_75_us;
};

static inline struct keene_device *to_keene_dev(struct v4l2_device *v4l2_dev)
{
        return container_of(v4l2_dev, struct keene_device, v4l2_dev);
}

/* Set frequency (if non-0), PA, mute and turn on/off the FM transmitter. */
static int keene_cmd_main(struct keene_device *radio, unsigned freq, bool play)
{
        unsigned short freq_send = freq ? (freq - 76 * 16000) / 800 : 0;
        int ret;

        radio->buffer[0] = 0x00;
        radio->buffer[1] = 0x50;
        radio->buffer[2] = (freq_send >> 8) & 0xff;
        radio->buffer[3] = freq_send & 0xff;
        radio->buffer[4] = radio->pa;
        /* If bit 4 is set, then tune to the frequency.
           If bit 3 is set, then unmute; if bit 2 is set, then mute.
           If bit 1 is set, then enter idle mode; if bit 0 is set,
           then enter transmit mode.
         */
        radio->buffer[5] = (radio->muted ? 4 : 8) | (play ? 1 : 2) |
                                                        (freq ? 0x10 : 0);
        radio->buffer[6] = 0x00;
        radio->buffer[7] = 0x00;

        ret = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
                9, 0x21, 0x200, 2, radio->buffer, BUFFER_LENGTH, USB_TIMEOUT);

        if (ret < 0) {
                dev_warn(&radio->vdev.dev, "%s failed (%d)\n", __func__, ret);
                return ret;
        }
        if (freq)
                radio->curfreq = freq;
        return 0;
}

/* Set TX, stereo and preemphasis mode (50 us vs 75 us). */
static int keene_cmd_set(struct keene_device *radio)
{
        int ret;

        radio->buffer[0] = 0x00;
        radio->buffer[1] = 0x51;
        radio->buffer[2] = radio->tx;
        /* If bit 0 is set, then transmit mono, otherwise stereo.
           If bit 2 is set, then enable 75 us preemphasis, otherwise
           it is 50 us. */
        radio->buffer[3] = (radio->stereo ? 0 : 1) | (radio->preemph_75_us ? 4 : 0);
        radio->buffer[4] = 0x00;
        radio->buffer[5] = 0x00;
        radio->buffer[6] = 0x00;
        radio->buffer[7] = 0x00;

        ret = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
                9, 0x21, 0x200, 2, radio->buffer, BUFFER_LENGTH, USB_TIMEOUT);

        if (ret < 0) {
                dev_warn(&radio->vdev.dev, "%s failed (%d)\n", __func__, ret);
                return ret;
        }
        return 0;
}

/* Handle unplugging the device.
 * We call video_unregister_device in any case.
 * The last function called in this procedure is
 * usb_keene_device_release.
 */
static void usb_keene_disconnect(struct usb_interface *intf)
{
        struct keene_device *radio = to_keene_dev(usb_get_intfdata(intf));

        mutex_lock(&radio->lock);
        usb_set_intfdata(intf, NULL);
        video_unregister_device(&radio->vdev);
        v4l2_device_disconnect(&radio->v4l2_dev);
        mutex_unlock(&radio->lock);
        v4l2_device_put(&radio->v4l2_dev);
}

static int usb_keene_suspend(struct usb_interface *intf, pm_message_t message)
{
        struct keene_device *radio = to_keene_dev(usb_get_intfdata(intf));

        return keene_cmd_main(radio, 0, false);
}

static int usb_keene_resume(struct usb_interface *intf)
{
        struct keene_device *radio = to_keene_dev(usb_get_intfdata(intf));

        mdelay(50);
        keene_cmd_set(radio);
        keene_cmd_main(radio, radio->curfreq, true);
        return 0;
}

static int vidioc_querycap(struct file *file, void *priv,
                                        struct v4l2_capability *v)
{
        struct keene_device *radio = video_drvdata(file);

        strlcpy(v->driver, "radio-keene", sizeof(v->driver));
        strlcpy(v->card, "Keene FM Transmitter", sizeof(v->card));
        usb_make_path(radio->usbdev, v->bus_info, sizeof(v->bus_info));
        v->device_caps = V4L2_CAP_RADIO | V4L2_CAP_MODULATOR;
        v->capabilities = v->device_caps | V4L2_CAP_DEVICE_CAPS;
        return 0;
}

static int vidioc_g_modulator(struct file *file, void *priv,
                                struct v4l2_modulator *v)
{
        struct keene_device *radio = video_drvdata(file);

        if (v->index > 0)
                return -EINVAL;

        strlcpy(v->name, "FM", sizeof(v->name));
        v->rangelow = FREQ_MIN * FREQ_MUL;
        v->rangehigh = FREQ_MAX * FREQ_MUL;
        v->txsubchans = radio->stereo ? V4L2_TUNER_SUB_STEREO : V4L2_TUNER_SUB_MONO;
        v->capability = V4L2_TUNER_CAP_LOW | V4L2_TUNER_CAP_STEREO;
        return 0;
}

static int vidioc_s_modulator(struct file *file, void *priv,
                                const struct v4l2_modulator *v)
{
        struct keene_device *radio = video_drvdata(file);

        if (v->index > 0)
                return -EINVAL;

        radio->stereo = (v->txsubchans == V4L2_TUNER_SUB_STEREO);
        return keene_cmd_set(radio);
}

static int vidioc_s_frequency(struct file *file, void *priv,
                                const struct v4l2_frequency *f)
{
        struct keene_device *radio = video_drvdata(file);
        unsigned freq = f->frequency;

        if (f->tuner != 0 || f->type != V4L2_TUNER_RADIO)
                return -EINVAL;
        freq = clamp(freq, FREQ_MIN * FREQ_MUL, FREQ_MAX * FREQ_MUL);
        return keene_cmd_main(radio, freq, true);
}

static int vidioc_g_frequency(struct file *file, void *priv,
                                struct v4l2_frequency *f)
{
        struct keene_device *radio = video_drvdata(file);

        if (f->tuner != 0)
                return -EINVAL;
        f->type = V4L2_TUNER_RADIO;
        f->frequency = radio->curfreq;
        return 0;
}

static int keene_s_ctrl(struct v4l2_ctrl *ctrl)
{
        static const u8 db2tx[] = {
             /*  -15,  -12,   -9,   -6,   -3,    0 dB */
                0x03, 0x13, 0x02, 0x12, 0x22, 0x32,
             /*    3,    6,    9,   12,   15,   18 dB */
                0x21, 0x31, 0x20, 0x30, 0x40, 0x50
        };
        struct keene_device *radio =
                container_of(ctrl->handler, struct keene_device, hdl);

        switch (ctrl->id) {
        case V4L2_CID_AUDIO_MUTE:
                radio->muted = ctrl->val;
                return keene_cmd_main(radio, 0, true);

        case V4L2_CID_TUNE_POWER_LEVEL:
                /* To go from dBuV to the register value we apply the
                   following formula: */
                radio->pa = (ctrl->val - 71) * 100 / 62;
                return keene_cmd_main(radio, 0, true);

        case V4L2_CID_TUNE_PREEMPHASIS:
                radio->preemph_75_us = ctrl->val == V4L2_PREEMPHASIS_75_uS;
                return keene_cmd_set(radio);

        case V4L2_CID_AUDIO_COMPRESSION_GAIN:
                radio->tx = db2tx[(ctrl->val - (s32)ctrl->minimum) / (s32)ctrl->step];
                return keene_cmd_set(radio);
        }
        return -EINVAL;
}

/* File system interface */
static const struct v4l2_file_operations usb_keene_fops = {
        .owner          = THIS_MODULE,
        .open           = v4l2_fh_open,
        .release        = v4l2_fh_release,
        .poll           = v4l2_ctrl_poll,
        .unlocked_ioctl = video_ioctl2,
};

static const struct v4l2_ctrl_ops keene_ctrl_ops = {
        .s_ctrl = keene_s_ctrl,
};

static const struct v4l2_ioctl_ops usb_keene_ioctl_ops = {
        .vidioc_querycap    = vidioc_querycap,
        .vidioc_g_modulator = vidioc_g_modulator,
        .vidioc_s_modulator = vidioc_s_modulator,
        .vidioc_g_frequency = vidioc_g_frequency,
        .vidioc_s_frequency = vidioc_s_frequency,
        .vidioc_log_status = v4l2_ctrl_log_status,
        .vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
        .vidioc_unsubscribe_event = v4l2_event_unsubscribe,
};

static void usb_keene_video_device_release(struct v4l2_device *v4l2_dev)
{
        struct keene_device *radio = to_keene_dev(v4l2_dev);

        /* free rest memory */
        v4l2_ctrl_handler_free(&radio->hdl);
        kfree(radio->buffer);
        kfree(radio);
}

/* check if the device is present and register with v4l and usb if it is */
static int usb_keene_probe(struct usb_interface *intf,
                                const struct usb_device_id *id)
{
        struct usb_device *dev = interface_to_usbdev(intf);
        struct keene_device *radio;
        struct v4l2_ctrl_handler *hdl;
        int retval = 0;

        /*
         * The Keene FM transmitter USB device has the same USB ID as
         * the Logitech AudioHub Speaker, but it should ignore the hid.
         * Check if the name is that of the Keene device.
         * If not, then someone connected the AudioHub and we shouldn't
         * attempt to handle this driver.
         * For reference: the product name of the AudioHub is
         * "AudioHub Speaker".
         */
        if (dev->product && strcmp(dev->product, "B-LINK USB Audio  "))
                return -ENODEV;

        radio = kzalloc(sizeof(struct keene_device), GFP_KERNEL);
        if (radio)
                radio->buffer = kmalloc(BUFFER_LENGTH, GFP_KERNEL);

        if (!radio || !radio->buffer) {
                dev_err(&intf->dev, "kmalloc for keene_device failed\n");
                kfree(radio);
                retval = -ENOMEM;
                goto err;
        }

        hdl = &radio->hdl;
        v4l2_ctrl_handler_init(hdl, 4);
        v4l2_ctrl_new_std(hdl, &keene_ctrl_ops, V4L2_CID_AUDIO_MUTE,
                        0, 1, 1, 0);
        v4l2_ctrl_new_std_menu(hdl, &keene_ctrl_ops, V4L2_CID_TUNE_PREEMPHASIS,
                        V4L2_PREEMPHASIS_75_uS, 1, V4L2_PREEMPHASIS_50_uS);
        v4l2_ctrl_new_std(hdl, &keene_ctrl_ops, V4L2_CID_TUNE_POWER_LEVEL,
                        84, 118, 1, 118);
        v4l2_ctrl_new_std(hdl, &keene_ctrl_ops, V4L2_CID_AUDIO_COMPRESSION_GAIN,
                        -15, 18, 3, 0);
        radio->pa = 118;
        radio->tx = 0x32;
        radio->stereo = true;
        if (hdl->error) {
                retval = hdl->error;

                v4l2_ctrl_handler_free(hdl);
                goto err_v4l2;
        }
        retval = v4l2_device_register(&intf->dev, &radio->v4l2_dev);
        if (retval < 0) {
                dev_err(&intf->dev, "couldn't register v4l2_device\n");
                goto err_v4l2;
        }

        mutex_init(&radio->lock);

        radio->v4l2_dev.ctrl_handler = hdl;
        radio->v4l2_dev.release = usb_keene_video_device_release;
        strlcpy(radio->vdev.name, radio->v4l2_dev.name,
                sizeof(radio->vdev.name));
        radio->vdev.v4l2_dev = &radio->v4l2_dev;
        radio->vdev.fops = &usb_keene_fops;
        radio->vdev.ioctl_ops = &usb_keene_ioctl_ops;
        radio->vdev.lock = &radio->lock;
        radio->vdev.release = video_device_release_empty;
        radio->vdev.vfl_dir = VFL_DIR_TX;

        radio->usbdev = interface_to_usbdev(intf);
        radio->intf = intf;
        usb_set_intfdata(intf, &radio->v4l2_dev);

        video_set_drvdata(&radio->vdev, radio);

        /* at least 11ms is needed in order to settle hardware */
        msleep(20);
        keene_cmd_main(radio, 95.16 * FREQ_MUL, false);

        retval = video_register_device(&radio->vdev, VFL_TYPE_RADIO, -1);
        if (retval < 0) {
                dev_err(&intf->dev, "could not register video device\n");
                goto err_vdev;
        }
        v4l2_ctrl_handler_setup(hdl);
        dev_info(&intf->dev, "V4L2 device registered as %s\n",
                        video_device_node_name(&radio->vdev));
        return 0;

err_vdev:
        v4l2_device_unregister(&radio->v4l2_dev);
err_v4l2:
        kfree(radio->buffer);
        kfree(radio);
err:
        return retval;
}

/* USB subsystem interface */
static struct usb_driver usb_keene_driver = {
        .name                   = "radio-keene",
        .probe                  = usb_keene_probe,
        .disconnect             = usb_keene_disconnect,
        .id_table               = usb_keene_device_table,
        .suspend                = usb_keene_suspend,
        .resume                 = usb_keene_resume,
        .reset_resume           = usb_keene_resume,
};

module_usb_driver(usb_keene_driver);