/*
 * lirc_ttusbir.c
 *
 * lirc_ttusbir - LIRC device driver for the TechnoTrend USB IR Receiver
 *
 * Copyright (C) 2007 Stefan Macher <st_maker-lirc@yahoo.de>
 *
 * This LIRC driver provides access to the TechnoTrend USB IR Receiver.
 * The receiver delivers the IR signal as raw sampled true/false data in
 * isochronous USB packets each of size 128 byte.
 * Currently the driver reduces the sampling rate by factor of 8 as this
 * is still more than enough to decode RC-5 - others should be analyzed.
 * But the driver does not rely on RC-5 it should be able to decode every
 * IR signal that is not too fast.
 */

/*
 *  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.
 *
 *  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/version.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/usb.h>

#include <media/lirc.h>
#include <media/lirc_dev.h>

MODULE_DESCRIPTION("TechnoTrend USB IR device driver for LIRC");
MODULE_AUTHOR("Stefan Macher (st_maker-lirc@yahoo.de)");
MODULE_LICENSE("GPL");

/* #define DEBUG */
#ifdef DEBUG
#define DPRINTK printk
#else
#define DPRINTK(_x_, a...)
#endif

/* function declarations */
static int probe(struct usb_interface *intf, const struct usb_device_id *id);
static void disconnect(struct usb_interface *intf);
static void urb_complete(struct urb *urb);
static int set_use_inc(void *data);
static void set_use_dec(void *data);

static int num_urbs = 2;
module_param(num_urbs, int, S_IRUGO);
MODULE_PARM_DESC(num_urbs,
                 "Number of URBs in queue. Try to increase to 4 in case "
                 "of problems (default: 2; minimum: 2)");

/* table of devices that work with this driver */
static struct usb_device_id device_id_table[] = {
        /* TechnoTrend USB IR Receiver */
        { USB_DEVICE(0x0B48, 0x2003) },
        /* Terminating entry */
        { }
};
MODULE_DEVICE_TABLE(usb, device_id_table);

/* USB driver definition */
static struct usb_driver usb_driver = {
        .name = "TTUSBIR",
        .id_table = &(device_id_table[0]),
        .probe = probe,
        .disconnect = disconnect,
};

/* USB device definition */
struct ttusbir_device {
        struct usb_driver *usb_driver;
        struct usb_device *udev;
        struct usb_interface *interf;
        struct usb_class_driver class_driver;
        unsigned int ifnum; /* Interface number to use */
        unsigned int alt_setting; /* alternate setting to use */
        unsigned int endpoint; /* Endpoint to use */
        struct urb **urb; /* num_urb URB pointers*/
        char **buffer; /* 128 byte buffer for each URB */
        struct lirc_buffer rbuf; /* Buffer towards LIRC */
        struct lirc_driver driver;
        int minor;
        int last_pulse; /* remembers if last received byte was pulse or space */
        int last_num; /* remembers how many last bytes appeared */
        int opened;
};

/*** LIRC specific functions ***/
static int set_use_inc(void *data)
{
        int i, retval;
        struct ttusbir_device *ttusbir = data;

        DPRINTK("Sending first URBs\n");
        /* @TODO Do I need to check if I am already opened */
        ttusbir->opened = 1;

        for (i = 0; i < num_urbs; i++) {
                retval = usb_submit_urb(ttusbir->urb[i], GFP_KERNEL);
                if (retval) {
                        err("%s: usb_submit_urb failed on urb %d",
                            __func__, i);
                        return retval;
                }
        }
        return 0;
}

static void set_use_dec(void *data)
{
        struct ttusbir_device *ttusbir = data;

        DPRINTK("Device closed\n");

        ttusbir->opened = 0;
}

/*** USB specific functions ***/

/*
 * This mapping table is used to do a very simple filtering of the
 * input signal.
 * For a value with at least 4 bits set it returns 0xFF otherwise
 * 0x00.  For faster IR signals this can not be used. But for RC-5 we
 * still have about 14 samples per pulse/space, i.e. we sample with 14
 * times higher frequency than the signal frequency
 */
const unsigned char map_table[] = {
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF,
        0x00, 0x00, 0x00, 0xFF, 0x00, 0xFF, 0xFF, 0xFF,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF,
        0x00, 0x00, 0x00, 0xFF, 0x00, 0xFF, 0xFF, 0xFF,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF,
        0x00, 0x00, 0x00, 0xFF, 0x00, 0xFF, 0xFF, 0xFF,
        0x00, 0x00, 0x00, 0xFF, 0x00, 0xFF, 0xFF, 0xFF,
        0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF,
        0x00, 0x00, 0x00, 0xFF, 0x00, 0xFF, 0xFF, 0xFF,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF,
        0x00, 0x00, 0x00, 0xFF, 0x00, 0xFF, 0xFF, 0xFF,
        0x00, 0x00, 0x00, 0xFF, 0x00, 0xFF, 0xFF, 0xFF,
        0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF,
        0x00, 0x00, 0x00, 0xFF, 0x00, 0xFF, 0xFF, 0xFF,
        0x00, 0x00, 0x00, 0xFF, 0x00, 0xFF, 0xFF, 0xFF,
        0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
        0x00, 0x00, 0x00, 0xFF, 0x00, 0xFF, 0xFF, 0xFF,
        0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
        0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
};

static void urb_complete(struct urb *urb)
{
        struct ttusbir_device *ttusbir;
        unsigned char *buf;
        int i;
        int l;

        ttusbir = urb->context;

        if (!ttusbir->opened)
                return;

        buf = (unsigned char *)urb->transfer_buffer;

        for (i = 0; i < 128; i++) {
                /* Here we do the filtering and some kind of down sampling */
                buf[i] = ~map_table[buf[i]];
                if (ttusbir->last_pulse == buf[i]) {
                        if (ttusbir->last_num < PULSE_MASK/63)
                                ttusbir->last_num++;
                /*
                 * else we are in a idle period and do not need to
                 * increment any longer
                 */
                } else {
                        l = ttusbir->last_num * 62; /* about 62 = us/byte */
                        if (ttusbir->last_pulse) /* pulse or space? */
                                l |= PULSE_BIT;
                        if (!lirc_buffer_full(&ttusbir->rbuf)) {
                                lirc_buffer_write(&ttusbir->rbuf, (void *)&l);
                                wake_up_interruptible(&ttusbir->rbuf.wait_poll);
                        }
                        ttusbir->last_num = 0;
                        ttusbir->last_pulse = buf[i];
                }
        }
        usb_submit_urb(urb, GFP_ATOMIC); /* keep data rolling :-) */
}

/*
 * Called whenever the USB subsystem thinks we could be the right driver
 * to handle this device
 */
static int probe(struct usb_interface *intf, const struct usb_device_id *id)
{
        int alt_set, endp;
        int found = 0;
        int i, j;
        int struct_size;
        struct usb_host_interface *host_interf;
        struct usb_interface_descriptor *interf_desc;
        struct usb_host_endpoint *host_endpoint;
        struct ttusbir_device *ttusbir;

        DPRINTK("Module ttusbir probe\n");

        /* To reduce memory fragmentation we use only one allocation */
        struct_size =  sizeof(struct ttusbir_device) +
                (sizeof(struct urb *) * num_urbs) +
                (sizeof(char *) * num_urbs) +
                (num_urbs * 128);
        ttusbir = kzalloc(struct_size, GFP_KERNEL);
        if (!ttusbir)
                return -ENOMEM;

        ttusbir->urb = (struct urb **)((char *)ttusbir +
                                      sizeof(struct ttusbir_device));
        ttusbir->buffer = (char **)((char *)ttusbir->urb +
                                   (sizeof(struct urb *) * num_urbs));
        for (i = 0; i < num_urbs; i++)
                ttusbir->buffer[i] = (char *)ttusbir->buffer +
                        (sizeof(char *)*num_urbs) + (i * 128);

        ttusbir->usb_driver = &usb_driver;
        ttusbir->alt_setting = -1;
        /* @TODO check if error can be returned */
        ttusbir->udev = usb_get_dev(interface_to_usbdev(intf));
        ttusbir->interf = intf;
        ttusbir->last_pulse = 0x00;
        ttusbir->last_num = 0;

        /*
         * Now look for interface setting we can handle
         * We are searching for the alt setting where end point
         * 0x82 has max packet size 16
         */
        for (alt_set = 0; alt_set < intf->num_altsetting && !found; alt_set++) {
                host_interf = &intf->altsetting[alt_set];
                interf_desc = &host_interf->desc;
                for (endp = 0; endp < interf_desc->bNumEndpoints; endp++) {
                        host_endpoint = &host_interf->endpoint[endp];
                        if ((host_endpoint->desc.bEndpointAddress == 0x82) &&
                            (host_endpoint->desc.wMaxPacketSize == 0x10)) {
                                ttusbir->alt_setting = alt_set;
                                ttusbir->endpoint = endp;
                                found = 1;
                                break;
                        }
                }
        }
        if (ttusbir->alt_setting != -1)
                DPRINTK("alt setting: %d\n", ttusbir->alt_setting);
        else {
                err("Could not find alternate setting\n");
                kfree(ttusbir);
                return -EINVAL;
        }

        /* OK lets setup this interface setting */
        usb_set_interface(ttusbir->udev, 0, ttusbir->alt_setting);

        /* Store device info in interface structure */
        usb_set_intfdata(intf, ttusbir);

        /* Register as a LIRC driver */
        if (lirc_buffer_init(&ttusbir->rbuf, sizeof(int), 256) < 0) {
                err("Could not get memory for LIRC data buffer\n");
                usb_set_intfdata(intf, NULL);
                kfree(ttusbir);
                return -ENOMEM;
        }
        strcpy(ttusbir->driver.name, "TTUSBIR");
        ttusbir->driver.minor = -1;
        ttusbir->driver.code_length = 1;
        ttusbir->driver.sample_rate = 0;
        ttusbir->driver.data = ttusbir;
        ttusbir->driver.add_to_buf = NULL;
        ttusbir->driver.rbuf = &ttusbir->rbuf;
        ttusbir->driver.set_use_inc = set_use_inc;
        ttusbir->driver.set_use_dec = set_use_dec;
        ttusbir->driver.dev = &intf->dev;
        ttusbir->driver.owner = THIS_MODULE;
        ttusbir->driver.features = LIRC_CAN_REC_MODE2;
        ttusbir->minor = lirc_register_driver(&ttusbir->driver);
        if (ttusbir->minor < 0) {
                err("Error registering as LIRC driver\n");
                usb_set_intfdata(intf, NULL);
                lirc_buffer_free(&ttusbir->rbuf);
                kfree(ttusbir);
                return -EIO;
        }

        /* Allocate and setup the URB that we will use to talk to the device */
        for (i = 0; i < num_urbs; i++) {
                ttusbir->urb[i] = usb_alloc_urb(8, GFP_KERNEL);
                if (!ttusbir->urb[i]) {
                        err("Could not allocate memory for the URB\n");
                        for (j = i - 1; j >= 0; j--)
                                kfree(ttusbir->urb[j]);
                        lirc_buffer_free(&ttusbir->rbuf);
                        lirc_unregister_driver(ttusbir->minor);
                        kfree(ttusbir);
                        usb_set_intfdata(intf, NULL);
                        return -ENOMEM;
                }
                ttusbir->urb[i]->dev = ttusbir->udev;
                ttusbir->urb[i]->context = ttusbir;
                ttusbir->urb[i]->pipe = usb_rcvisocpipe(ttusbir->udev,
                                                        ttusbir->endpoint);
                ttusbir->urb[i]->interval = 1;
                ttusbir->urb[i]->transfer_flags = URB_ISO_ASAP;
                ttusbir->urb[i]->transfer_buffer = &ttusbir->buffer[i][0];
                ttusbir->urb[i]->complete = urb_complete;
                ttusbir->urb[i]->number_of_packets = 8;
                ttusbir->urb[i]->transfer_buffer_length = 128;
                for (j = 0; j < 8; j++) {
                        ttusbir->urb[i]->iso_frame_desc[j].offset = j*16;
                        ttusbir->urb[i]->iso_frame_desc[j].length = 16;
                }
        }
        return 0;
}

/**
 * Called when the driver is unloaded or the device is unplugged
 */
static void disconnect(struct usb_interface *intf)
{
        int i;
        struct ttusbir_device *ttusbir;

        DPRINTK("Module ttusbir disconnect\n");

        ttusbir = (struct ttusbir_device *) usb_get_intfdata(intf);
        usb_set_intfdata(intf, NULL);
        lirc_unregister_driver(ttusbir->minor);
        DPRINTK("unregistered\n");

        for (i = 0; i < num_urbs; i++) {
                usb_kill_urb(ttusbir->urb[i]);
                usb_free_urb(ttusbir->urb[i]);
        }
        DPRINTK("URBs killed\n");
        lirc_buffer_free(&ttusbir->rbuf);
        kfree(ttusbir);
}

static int ttusbir_init_module(void)
{
        int result;

        DPRINTK(KERN_DEBUG "Module ttusbir init\n");

        /* register this driver with the USB subsystem */
        result = usb_register(&usb_driver);
        if (result)
                err("usb_register failed. Error number %d", result);
        return result;
}

static void ttusbir_exit_module(void)
{
        printk(KERN_DEBUG "Module ttusbir exit\n");
        usb_deregister(&usb_driver);
}

module_init(ttusbir_init_module);
module_exit(ttusbir_exit_module);