/*
 * keyspan_remote: USB driver for the Keyspan DMR
 *
 * Copyright (C) 2005 Zymeta Corporation - Michael Downey (downey@zymeta.com)
 *
 *      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, version 2.
 *
 * This driver has been put together with the support of Innosys, Inc.
 * and Keyspan, Inc the manufacturers of the Keyspan USB DMR product.
 */

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

#define DRIVER_VERSION  "v0.1"
#define DRIVER_AUTHOR   "Michael Downey <downey@zymeta.com>"
#define DRIVER_DESC     "Driver for the USB Keyspan remote control."
#define DRIVER_LICENSE  "GPL"

/* Parameters that can be passed to the driver. */
static int debug;
module_param(debug, int, 0444);
MODULE_PARM_DESC(debug, "Enable extra debug messages and information");

/* Vendor and product ids */
#define USB_KEYSPAN_VENDOR_ID           0x06CD
#define USB_KEYSPAN_PRODUCT_UIA11       0x0202

/* Defines for converting the data from the remote. */
#define ZERO            0x18
#define ZERO_MASK       0x1F    /* 5 bits for a 0 */
#define ONE             0x3C
#define ONE_MASK        0x3F    /* 6 bits for a 1 */
#define SYNC            0x3F80
#define SYNC_MASK       0x3FFF  /* 14 bits for a SYNC sequence */
#define STOP            0x00
#define STOP_MASK       0x1F    /* 5 bits for the STOP sequence */
#define GAP             0xFF

#define RECV_SIZE       8       /* The UIA-11 type have a 8 byte limit. */

/*
 * Table that maps the 31 possible keycodes to input keys.
 * Currently there are 15 and 17 button models so RESERVED codes
 * are blank areas in the mapping.
 */
static const unsigned short keyspan_key_table[] = {
        KEY_RESERVED,           /* 0 is just a place holder. */
        KEY_RESERVED,
        KEY_STOP,
        KEY_PLAYCD,
        KEY_RESERVED,
        KEY_PREVIOUSSONG,
        KEY_REWIND,
        KEY_FORWARD,
        KEY_NEXTSONG,
        KEY_RESERVED,
        KEY_RESERVED,
        KEY_RESERVED,
        KEY_PAUSE,
        KEY_VOLUMEUP,
        KEY_RESERVED,
        KEY_RESERVED,
        KEY_RESERVED,
        KEY_VOLUMEDOWN,
        KEY_RESERVED,
        KEY_UP,
        KEY_RESERVED,
        KEY_MUTE,
        KEY_LEFT,
        KEY_ENTER,
        KEY_RIGHT,
        KEY_RESERVED,
        KEY_RESERVED,
        KEY_DOWN,
        KEY_RESERVED,
        KEY_KPASTERISK,
        KEY_RESERVED,
        KEY_MENU
};

/* table of devices that work with this driver */
static struct usb_device_id keyspan_table[] = {
        { USB_DEVICE(USB_KEYSPAN_VENDOR_ID, USB_KEYSPAN_PRODUCT_UIA11) },
        { }                                     /* Terminating entry */
};

/* Structure to store all the real stuff that a remote sends to us. */
struct keyspan_message {
        u16     system;
        u8      button;
        u8      toggle;
};

/* Structure used for all the bit testing magic needed to be done. */
struct bit_tester {
        u32     tester;
        int     len;
        int     pos;
        int     bits_left;
        u8      buffer[32];
};

/* Structure to hold all of our driver specific stuff */
struct usb_keyspan {
        char                            name[128];
        char                            phys[64];
        unsigned short                  keymap[ARRAY_SIZE(keyspan_key_table)];
        struct usb_device               *udev;
        struct input_dev                *input;
        struct usb_interface            *interface;
        struct usb_endpoint_descriptor  *in_endpoint;
        struct urb*                     irq_urb;
        int                             open;
        dma_addr_t                      in_dma;
        unsigned char                   *in_buffer;

        /* variables used to parse messages from remote. */
        struct bit_tester               data;
        int                             stage;
        int                             toggle;
};

static struct usb_driver keyspan_driver;

/*
 * Debug routine that prints out what we've received from the remote.
 */
static void keyspan_print(struct usb_keyspan* dev) /*unsigned char* data)*/
{
        char codes[4 * RECV_SIZE];
        int i;

        for (i = 0; i < RECV_SIZE; i++)
                snprintf(codes + i * 3, 4, "%02x ", dev->in_buffer[i]);

        dev_info(&dev->udev->dev, "%s\n", codes);
}

/*
 * Routine that manages the bit_tester structure.  It makes sure that there are
 * at least bits_needed bits loaded into the tester.
 */
static int keyspan_load_tester(struct usb_keyspan* dev, int bits_needed)
{
        if (dev->data.bits_left >= bits_needed)
                return 0;

        /*
         * Somehow we've missed the last message. The message will be repeated
         * though so it's not too big a deal
         */
        if (dev->data.pos >= dev->data.len) {
                dev_dbg(&dev->udev->dev,
                        "%s - Error ran out of data. pos: %d, len: %d\n",
                        __func__, dev->data.pos, dev->data.len);
                return -1;
        }

        /* Load as much as we can into the tester. */
        while ((dev->data.bits_left + 7 < (sizeof(dev->data.tester) * 8)) &&
               (dev->data.pos < dev->data.len)) {
                dev->data.tester += (dev->data.buffer[dev->data.pos++] << dev->data.bits_left);
                dev->data.bits_left += 8;
        }

        return 0;
}

static void keyspan_report_button(struct usb_keyspan *remote, int button, int press)
{
        struct input_dev *input = remote->input;

        input_event(input, EV_MSC, MSC_SCAN, button);
        input_report_key(input, remote->keymap[button], press);
        input_sync(input);
}

/*
 * Routine that handles all the logic needed to parse out the message from the remote.
 */
static void keyspan_check_data(struct usb_keyspan *remote)
{
        int i;
        int found = 0;
        struct keyspan_message message;

        switch(remote->stage) {
        case 0:
                /*
                 * In stage 0 we want to find the start of a message.  The remote sends a 0xFF as filler.
                 * So the first byte that isn't a FF should be the start of a new message.
                 */
                for (i = 0; i < RECV_SIZE && remote->in_buffer[i] == GAP; ++i);

                if (i < RECV_SIZE) {
                        memcpy(remote->data.buffer, remote->in_buffer, RECV_SIZE);
                        remote->data.len = RECV_SIZE;
                        remote->data.pos = 0;
                        remote->data.tester = 0;
                        remote->data.bits_left = 0;
                        remote->stage = 1;
                }
                break;

        case 1:
                /*
                 * Stage 1 we should have 16 bytes and should be able to detect a
                 * SYNC.  The SYNC is 14 bits, 7 0's and then 7 1's.
                 */
                memcpy(remote->data.buffer + remote->data.len, remote->in_buffer, RECV_SIZE);
                remote->data.len += RECV_SIZE;

                found = 0;
                while ((remote->data.bits_left >= 14 || remote->data.pos < remote->data.len) && !found) {
                        for (i = 0; i < 8; ++i) {
                                if (keyspan_load_tester(remote, 14) != 0) {
                                        remote->stage = 0;
                                        return;
                                }

                                if ((remote->data.tester & SYNC_MASK) == SYNC) {
                                        remote->data.tester = remote->data.tester >> 14;
                                        remote->data.bits_left -= 14;
                                        found = 1;
                                        break;
                                } else {
                                        remote->data.tester = remote->data.tester >> 1;
                                        --remote->data.bits_left;
                                }
                        }
                }

                if (!found) {
                        remote->stage = 0;
                        remote->data.len = 0;
                } else {
                        remote->stage = 2;
                }
                break;

        case 2:
                /*
                 * Stage 2 we should have 24 bytes which will be enough for a full
                 * message.  We need to parse out the system code, button code,
                 * toggle code, and stop.
                 */
                memcpy(remote->data.buffer + remote->data.len, remote->in_buffer, RECV_SIZE);
                remote->data.len += RECV_SIZE;

                message.system = 0;
                for (i = 0; i < 9; i++) {
                        keyspan_load_tester(remote, 6);

                        if ((remote->data.tester & ZERO_MASK) == ZERO) {
                                message.system = message.system << 1;
                                remote->data.tester = remote->data.tester >> 5;
                                remote->data.bits_left -= 5;
                        } else if ((remote->data.tester & ONE_MASK) == ONE) {
                                message.system = (message.system << 1) + 1;
                                remote->data.tester = remote->data.tester >> 6;
                                remote->data.bits_left -= 6;
                        } else {
                                err("%s - Unknown sequence found in system data.\n", __func__);
                                remote->stage = 0;
                                return;
                        }
                }

                message.button = 0;
                for (i = 0; i < 5; i++) {
                        keyspan_load_tester(remote, 6);

                        if ((remote->data.tester & ZERO_MASK) == ZERO) {
                                message.button = message.button << 1;
                                remote->data.tester = remote->data.tester >> 5;
                                remote->data.bits_left -= 5;
                        } else if ((remote->data.tester & ONE_MASK) == ONE) {
                                message.button = (message.button << 1) + 1;
                                remote->data.tester = remote->data.tester >> 6;
                                remote->data.bits_left -= 6;
                        } else {
                                err("%s - Unknown sequence found in button data.\n", __func__);
                                remote->stage = 0;
                                return;
                        }
                }

                keyspan_load_tester(remote, 6);
                if ((remote->data.tester & ZERO_MASK) == ZERO) {
                        message.toggle = 0;
                        remote->data.tester = remote->data.tester >> 5;
                        remote->data.bits_left -= 5;
                } else if ((remote->data.tester & ONE_MASK) == ONE) {
                        message.toggle = 1;
                        remote->data.tester = remote->data.tester >> 6;
                        remote->data.bits_left -= 6;
                } else {
                        err("%s - Error in message, invalid toggle.\n", __func__);
                        remote->stage = 0;
                        return;
                }

                keyspan_load_tester(remote, 5);
                if ((remote->data.tester & STOP_MASK) == STOP) {
                        remote->data.tester = remote->data.tester >> 5;
                        remote->data.bits_left -= 5;
                } else {
                        err("Bad message recieved, no stop bit found.\n");
                }

                dev_dbg(&remote->udev->dev,
                        "%s found valid message: system: %d, button: %d, toggle: %d\n",
                        __func__, message.system, message.button, message.toggle);

                if (message.toggle != remote->toggle) {
                        keyspan_report_button(remote, message.button, 1);
                        keyspan_report_button(remote, message.button, 0);
                        remote->toggle = message.toggle;
                }

                remote->stage = 0;
                break;
        }
}

/*
 * Routine for sending all the initialization messages to the remote.
 */
static int keyspan_setup(struct usb_device* dev)
{
        int retval = 0;

        retval = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                                 0x11, 0x40, 0x5601, 0x0, NULL, 0, 0);
        if (retval) {
                dev_dbg(&dev->dev, "%s - failed to set bit rate due to error: %d\n",
                        __func__, retval);
                return(retval);
        }

        retval = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                                 0x44, 0x40, 0x0, 0x0, NULL, 0, 0);
        if (retval) {
                dev_dbg(&dev->dev, "%s - failed to set resume sensitivity due to error: %d\n",
                        __func__, retval);
                return(retval);
        }

        retval = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                                 0x22, 0x40, 0x0, 0x0, NULL, 0, 0);
        if (retval) {
                dev_dbg(&dev->dev, "%s - failed to turn receive on due to error: %d\n",
                        __func__, retval);
                return(retval);
        }

        dev_dbg(&dev->dev, "%s - Setup complete.\n", __func__);
        return(retval);
}

/*
 * Routine used to handle a new message that has come in.
 */
static void keyspan_irq_recv(struct urb *urb)
{
        struct usb_keyspan *dev = urb->context;
        int retval;

        /* Check our status in case we need to bail out early. */
        switch (urb->status) {
        case 0:
                break;

        /* Device went away so don't keep trying to read from it. */
        case -ECONNRESET:
        case -ENOENT:
        case -ESHUTDOWN:
                return;

        default:
                goto resubmit;
                break;
        }

        if (debug)
                keyspan_print(dev);

        keyspan_check_data(dev);

resubmit:
        retval = usb_submit_urb(urb, GFP_ATOMIC);
        if (retval)
                err ("%s - usb_submit_urb failed with result: %d", __func__, retval);
}

static int keyspan_open(struct input_dev *dev)
{
        struct usb_keyspan *remote = input_get_drvdata(dev);

        remote->irq_urb->dev = remote->udev;
        if (usb_submit_urb(remote->irq_urb, GFP_KERNEL))
                return -EIO;

        return 0;
}

static void keyspan_close(struct input_dev *dev)
{
        struct usb_keyspan *remote = input_get_drvdata(dev);

        usb_kill_urb(remote->irq_urb);
}

static struct usb_endpoint_descriptor *keyspan_get_in_endpoint(struct usb_host_interface *iface)
{

        struct usb_endpoint_descriptor *endpoint;
        int i;

        for (i = 0; i < iface->desc.bNumEndpoints; ++i) {
                endpoint = &iface->endpoint[i].desc;

                if (usb_endpoint_is_int_in(endpoint)) {
                        /* we found our interrupt in endpoint */
                        return endpoint;
                }
        }

        return NULL;
}

/*
 * Routine that sets up the driver to handle a specific USB device detected on the bus.
 */
static int keyspan_probe(struct usb_interface *interface, const struct usb_device_id *id)
{
        struct usb_device *udev = interface_to_usbdev(interface);
        struct usb_endpoint_descriptor *endpoint;
        struct usb_keyspan *remote;
        struct input_dev *input_dev;
        int i, error;

        endpoint = keyspan_get_in_endpoint(interface->cur_altsetting);
        if (!endpoint)
                return -ENODEV;

        remote = kzalloc(sizeof(*remote), GFP_KERNEL);
        input_dev = input_allocate_device();
        if (!remote || !input_dev) {
                error = -ENOMEM;
                goto fail1;
        }

        remote->udev = udev;
        remote->input = input_dev;
        remote->interface = interface;
        remote->in_endpoint = endpoint;
        remote->toggle = -1;    /* Set to -1 so we will always not match the toggle from the first remote message. */

        remote->in_buffer = usb_buffer_alloc(udev, RECV_SIZE, GFP_ATOMIC, &remote->in_dma);
        if (!remote->in_buffer) {
                error = -ENOMEM;
                goto fail1;
        }

        remote->irq_urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!remote->irq_urb) {
                error = -ENOMEM;
                goto fail2;
        }

        error = keyspan_setup(udev);
        if (error) {
                error = -ENODEV;
                goto fail3;
        }

        if (udev->manufacturer)
                strlcpy(remote->name, udev->manufacturer, sizeof(remote->name));

        if (udev->product) {
                if (udev->manufacturer)
                        strlcat(remote->name, " ", sizeof(remote->name));
                strlcat(remote->name, udev->product, sizeof(remote->name));
        }

        if (!strlen(remote->name))
                snprintf(remote->name, sizeof(remote->name),
                         "USB Keyspan Remote %04x:%04x",
                         le16_to_cpu(udev->descriptor.idVendor),
                         le16_to_cpu(udev->descriptor.idProduct));

        usb_make_path(udev, remote->phys, sizeof(remote->phys));
        strlcat(remote->phys, "/input0", sizeof(remote->phys));
        memcpy(remote->keymap, keyspan_key_table, sizeof(remote->keymap));

        input_dev->name = remote->name;
        input_dev->phys = remote->phys;
        usb_to_input_id(udev, &input_dev->id);
        input_dev->dev.parent = &interface->dev;
        input_dev->keycode = remote->keymap;
        input_dev->keycodesize = sizeof(unsigned short);
        input_dev->keycodemax = ARRAY_SIZE(remote->keymap);

        input_set_capability(input_dev, EV_MSC, MSC_SCAN);
        __set_bit(EV_KEY, input_dev->evbit);
        for (i = 0; i < ARRAY_SIZE(keyspan_key_table); i++)
                __set_bit(keyspan_key_table[i], input_dev->keybit);
        __clear_bit(KEY_RESERVED, input_dev->keybit);

        input_set_drvdata(input_dev, remote);

        input_dev->open = keyspan_open;
        input_dev->close = keyspan_close;

        /*
         * Initialize the URB to access the device.
         * The urb gets sent to the device in keyspan_open()
         */
        usb_fill_int_urb(remote->irq_urb,
                         remote->udev,
                         usb_rcvintpipe(remote->udev, endpoint->bEndpointAddress),
                         remote->in_buffer, RECV_SIZE, keyspan_irq_recv, remote,
                         endpoint->bInterval);
        remote->irq_urb->transfer_dma = remote->in_dma;
        remote->irq_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

        /* we can register the device now, as it is ready */
        error = input_register_device(remote->input);
        if (error)
                goto fail3;

        /* save our data pointer in this interface device */
        usb_set_intfdata(interface, remote);

        return 0;

 fail3: usb_free_urb(remote->irq_urb);
 fail2: usb_buffer_free(udev, RECV_SIZE, remote->in_buffer, remote->in_dma);
 fail1: kfree(remote);
        input_free_device(input_dev);

        return error;
}

/*
 * Routine called when a device is disconnected from the USB.
 */
static void keyspan_disconnect(struct usb_interface *interface)
{
        struct usb_keyspan *remote;

        remote = usb_get_intfdata(interface);
        usb_set_intfdata(interface, NULL);

        if (remote) {   /* We have a valid driver structure so clean up everything we allocated. */
                input_unregister_device(remote->input);
                usb_kill_urb(remote->irq_urb);
                usb_free_urb(remote->irq_urb);
                usb_buffer_free(remote->udev, RECV_SIZE, remote->in_buffer, remote->in_dma);
                kfree(remote);
        }
}

/*
 * Standard driver set up sections
 */
static struct usb_driver keyspan_driver =
{
        .name =         "keyspan_remote",
        .probe =        keyspan_probe,
        .disconnect =   keyspan_disconnect,
        .id_table =     keyspan_table
};

static int __init usb_keyspan_init(void)
{
        int result;

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

        return result;
}

static void __exit usb_keyspan_exit(void)
{
        /* deregister this driver with the USB subsystem */
        usb_deregister(&keyspan_driver);
}

module_init(usb_keyspan_init);
module_exit(usb_keyspan_exit);

MODULE_DEVICE_TABLE(usb, keyspan_table);
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE(DRIVER_LICENSE);