/*
 * IguanaWorks USB IR Transceiver support
 *
 * Copyright (C) 2012 Sean Young <sean@mess.org>
 *
 * 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.
 */

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/usb/input.h>
#include <linux/slab.h>
#include <linux/completion.h>
#include <media/rc-core.h>

#define DRIVER_NAME "iguanair"
#define BUF_SIZE 152

struct iguanair {
        struct rc_dev *rc;

        struct device *dev;
        struct usb_device *udev;

        uint16_t version;
        uint8_t bufsize;
        uint8_t cycle_overhead;

        struct mutex lock;

        /* receiver support */
        bool receiver_on;
        dma_addr_t dma_in, dma_out;
        uint8_t *buf_in;
        struct urb *urb_in, *urb_out;
        struct completion completion;

        /* transmit support */
        bool tx_overflow;
        uint32_t carrier;
        struct send_packet *packet;

        char name[64];
        char phys[64];
};

#define CMD_NOP                 0x00
#define CMD_GET_VERSION         0x01
#define CMD_GET_BUFSIZE         0x11
#define CMD_GET_FEATURES        0x10
#define CMD_SEND                0x15
#define CMD_EXECUTE             0x1f
#define CMD_RX_OVERFLOW         0x31
#define CMD_TX_OVERFLOW         0x32
#define CMD_RECEIVER_ON         0x12
#define CMD_RECEIVER_OFF        0x14

#define DIR_IN                  0xdc
#define DIR_OUT                 0xcd

#define MAX_IN_PACKET           8u
#define MAX_OUT_PACKET          (sizeof(struct send_packet) + BUF_SIZE)
#define TIMEOUT                 1000
#define RX_RESOLUTION           21333

struct packet {
        uint16_t start;
        uint8_t direction;
        uint8_t cmd;
};

struct send_packet {
        struct packet header;
        uint8_t length;
        uint8_t channels;
        uint8_t busy7;
        uint8_t busy4;
        uint8_t payload[0];
};

static void process_ir_data(struct iguanair *ir, unsigned len)
{
        if (len >= 4 && ir->buf_in[0] == 0 && ir->buf_in[1] == 0) {
                switch (ir->buf_in[3]) {
                case CMD_GET_VERSION:
                        if (len == 6) {
                                ir->version = (ir->buf_in[5] << 8) |
                                                        ir->buf_in[4];
                                complete(&ir->completion);
                        }
                        break;
                case CMD_GET_BUFSIZE:
                        if (len >= 5) {
                                ir->bufsize = ir->buf_in[4];
                                complete(&ir->completion);
                        }
                        break;
                case CMD_GET_FEATURES:
                        if (len > 5) {
                                ir->cycle_overhead = ir->buf_in[5];
                                complete(&ir->completion);
                        }
                        break;
                case CMD_TX_OVERFLOW:
                        ir->tx_overflow = true;
                        /* fall through */
                case CMD_RECEIVER_OFF:
                case CMD_RECEIVER_ON:
                case CMD_SEND:
                        complete(&ir->completion);
                        break;
                case CMD_RX_OVERFLOW:
                        dev_warn(ir->dev, "receive overflow\n");
                        ir_raw_event_reset(ir->rc);
                        break;
                default:
                        dev_warn(ir->dev, "control code %02x received\n",
                                                        ir->buf_in[3]);
                        break;
                }
        } else if (len >= 7) {
                DEFINE_IR_RAW_EVENT(rawir);
                unsigned i;
                bool event = false;

                init_ir_raw_event(&rawir);

                for (i = 0; i < 7; i++) {
                        if (ir->buf_in[i] == 0x80) {
                                rawir.pulse = false;
                                rawir.duration = US_TO_NS(21845);
                        } else {
                                rawir.pulse = (ir->buf_in[i] & 0x80) == 0;
                                rawir.duration = ((ir->buf_in[i] & 0x7f) + 1) *
                                                                 RX_RESOLUTION;
                        }

                        if (ir_raw_event_store_with_filter(ir->rc, &rawir))
                                event = true;
                }

                if (event)
                        ir_raw_event_handle(ir->rc);
        }
}

static void iguanair_rx(struct urb *urb)
{
        struct iguanair *ir;
        int rc;

        if (!urb)
                return;

        ir = urb->context;
        if (!ir) {
                usb_unlink_urb(urb);
                return;
        }

        switch (urb->status) {
        case 0:
                process_ir_data(ir, urb->actual_length);
                break;
        case -ECONNRESET:
        case -ENOENT:
        case -ESHUTDOWN:
                usb_unlink_urb(urb);
                return;
        case -EPIPE:
        default:
                dev_dbg(ir->dev, "Error: urb status = %d\n", urb->status);
                break;
        }

        rc = usb_submit_urb(urb, GFP_ATOMIC);
        if (rc && rc != -ENODEV)
                dev_warn(ir->dev, "failed to resubmit urb: %d\n", rc);
}

static void iguanair_irq_out(struct urb *urb)
{
        struct iguanair *ir = urb->context;

        if (urb->status)
                dev_dbg(ir->dev, "Error: out urb status = %d\n", urb->status);

        /* if we sent an nop packet, do not expect a response */
        if (urb->status == 0 && ir->packet->header.cmd == CMD_NOP)
                complete(&ir->completion);
}

static int iguanair_send(struct iguanair *ir, unsigned size)
{
        int rc;

        reinit_completion(&ir->completion);

        ir->urb_out->transfer_buffer_length = size;
        rc = usb_submit_urb(ir->urb_out, GFP_KERNEL);
        if (rc)
                return rc;

        if (wait_for_completion_timeout(&ir->completion, TIMEOUT) == 0)
                return -ETIMEDOUT;

        return rc;
}

static int iguanair_get_features(struct iguanair *ir)
{
        int rc;

        /*
         * On cold boot, the iguanair initializes on the first packet
         * received but does not process that packet. Send an empty
         * packet.
         */
        ir->packet->header.start = 0;
        ir->packet->header.direction = DIR_OUT;
        ir->packet->header.cmd = CMD_NOP;
        iguanair_send(ir, sizeof(ir->packet->header));

        ir->packet->header.cmd = CMD_GET_VERSION;
        rc = iguanair_send(ir, sizeof(ir->packet->header));
        if (rc) {
                dev_info(ir->dev, "failed to get version\n");
                goto out;
        }

        if (ir->version < 0x205) {
                dev_err(ir->dev, "firmware 0x%04x is too old\n", ir->version);
                rc = -ENODEV;
                goto out;
        }

        ir->bufsize = 150;
        ir->cycle_overhead = 65;

        ir->packet->header.cmd = CMD_GET_BUFSIZE;

        rc = iguanair_send(ir, sizeof(ir->packet->header));
        if (rc) {
                dev_info(ir->dev, "failed to get buffer size\n");
                goto out;
        }

        if (ir->bufsize > BUF_SIZE) {
                dev_info(ir->dev, "buffer size %u larger than expected\n",
                                                                ir->bufsize);
                ir->bufsize = BUF_SIZE;
        }

        ir->packet->header.cmd = CMD_GET_FEATURES;

        rc = iguanair_send(ir, sizeof(ir->packet->header));
        if (rc)
                dev_info(ir->dev, "failed to get features\n");
out:
        return rc;
}

static int iguanair_receiver(struct iguanair *ir, bool enable)
{
        ir->packet->header.start = 0;
        ir->packet->header.direction = DIR_OUT;
        ir->packet->header.cmd = enable ? CMD_RECEIVER_ON : CMD_RECEIVER_OFF;

        if (enable)
                ir_raw_event_reset(ir->rc);

        return iguanair_send(ir, sizeof(ir->packet->header));
}

/*
 * The iguanair creates the carrier by busy spinning after each half period.
 * This is counted in CPU cycles, with the CPU running at 24MHz. It is
 * broken down into 7-cycles and 4-cyles delays, with a preference for
 * 4-cycle delays, minus the overhead of the loop itself (cycle_overhead).
 */
static int iguanair_set_tx_carrier(struct rc_dev *dev, uint32_t carrier)
{
        struct iguanair *ir = dev->priv;

        if (carrier < 25000 || carrier > 150000)
                return -EINVAL;

        mutex_lock(&ir->lock);

        if (carrier != ir->carrier) {
                uint32_t cycles, fours, sevens;

                ir->carrier = carrier;

                cycles = DIV_ROUND_CLOSEST(24000000, carrier * 2) -
                                                        ir->cycle_overhead;

                /*
                 * Calculate minimum number of 7 cycles needed so
                 * we are left with a multiple of 4; so we want to have
                 * (sevens * 7) & 3 == cycles & 3
                 */
                sevens = (4 - cycles) & 3;
                fours = (cycles - sevens * 7) / 4;

                /*
                 * The firmware interprets these values as a relative offset
                 * for a branch. Immediately following the branches, there
                 * 4 instructions of 7 cycles (2 bytes each) and 110
                 * instructions of 4 cycles (1 byte each). A relative branch
                 * of 0 will execute all of them, branch further for less
                 * cycle burning.
                 */
                ir->packet->busy7 = (4 - sevens) * 2;
                ir->packet->busy4 = 110 - fours;
        }

        mutex_unlock(&ir->lock);

        return 0;
}

static int iguanair_set_tx_mask(struct rc_dev *dev, uint32_t mask)
{
        struct iguanair *ir = dev->priv;

        if (mask > 15)
                return 4;

        mutex_lock(&ir->lock);
        ir->packet->channels = mask << 4;
        mutex_unlock(&ir->lock);

        return 0;
}

static int iguanair_tx(struct rc_dev *dev, unsigned *txbuf, unsigned count)
{
        struct iguanair *ir = dev->priv;
        unsigned int i, size, p, periods;
        int rc;

        mutex_lock(&ir->lock);

        /* convert from us to carrier periods */
        for (i = size = 0; i < count; i++) {
                periods = DIV_ROUND_CLOSEST(txbuf[i] * ir->carrier, 1000000);
                while (periods) {
                        p = min(periods, 127u);
                        if (size >= ir->bufsize) {
                                rc = -EINVAL;
                                goto out;
                        }
                        ir->packet->payload[size++] = p | ((i & 1) ? 0x80 : 0);
                        periods -= p;
                }
        }

        ir->packet->header.start = 0;
        ir->packet->header.direction = DIR_OUT;
        ir->packet->header.cmd = CMD_SEND;
        ir->packet->length = size;

        ir->tx_overflow = false;

        rc = iguanair_send(ir, sizeof(*ir->packet) + size);

        if (rc == 0 && ir->tx_overflow)
                rc = -EOVERFLOW;

out:
        mutex_unlock(&ir->lock);

        return rc ? rc : count;
}

static int iguanair_open(struct rc_dev *rdev)
{
        struct iguanair *ir = rdev->priv;
        int rc;

        mutex_lock(&ir->lock);

        rc = iguanair_receiver(ir, true);
        if (rc == 0)
                ir->receiver_on = true;

        mutex_unlock(&ir->lock);

        return rc;
}

static void iguanair_close(struct rc_dev *rdev)
{
        struct iguanair *ir = rdev->priv;
        int rc;

        mutex_lock(&ir->lock);

        rc = iguanair_receiver(ir, false);
        ir->receiver_on = false;
        if (rc && rc != -ENODEV)
                dev_warn(ir->dev, "failed to disable receiver: %d\n", rc);

        mutex_unlock(&ir->lock);
}

static int iguanair_probe(struct usb_interface *intf,
                          const struct usb_device_id *id)
{
        struct usb_device *udev = interface_to_usbdev(intf);
        struct iguanair *ir;
        struct rc_dev *rc;
        int ret, pipein, pipeout;
        struct usb_host_interface *idesc;

        ir = kzalloc(sizeof(*ir), GFP_KERNEL);
        rc = rc_allocate_device(RC_DRIVER_IR_RAW);
        if (!ir || !rc) {
                ret = -ENOMEM;
                goto out;
        }

        ir->buf_in = usb_alloc_coherent(udev, MAX_IN_PACKET, GFP_KERNEL,
                                                                &ir->dma_in);
        ir->packet = usb_alloc_coherent(udev, MAX_OUT_PACKET, GFP_KERNEL,
                                                                &ir->dma_out);
        ir->urb_in = usb_alloc_urb(0, GFP_KERNEL);
        ir->urb_out = usb_alloc_urb(0, GFP_KERNEL);

        if (!ir->buf_in || !ir->packet || !ir->urb_in || !ir->urb_out) {
                ret = -ENOMEM;
                goto out;
        }

        idesc = intf->altsetting;

        if (idesc->desc.bNumEndpoints < 2) {
                ret = -ENODEV;
                goto out;
        }

        ir->rc = rc;
        ir->dev = &intf->dev;
        ir->udev = udev;
        mutex_init(&ir->lock);

        init_completion(&ir->completion);
        pipeout = usb_sndintpipe(udev,
                                idesc->endpoint[1].desc.bEndpointAddress);
        usb_fill_int_urb(ir->urb_out, udev, pipeout, ir->packet, MAX_OUT_PACKET,
                                                iguanair_irq_out, ir, 1);
        ir->urb_out->transfer_dma = ir->dma_out;
        ir->urb_out->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

        pipein = usb_rcvintpipe(udev, idesc->endpoint[0].desc.bEndpointAddress);
        usb_fill_int_urb(ir->urb_in, udev, pipein, ir->buf_in, MAX_IN_PACKET,
                                                         iguanair_rx, ir, 1);
        ir->urb_in->transfer_dma = ir->dma_in;
        ir->urb_in->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

        ret = usb_submit_urb(ir->urb_in, GFP_KERNEL);
        if (ret) {
                dev_warn(&intf->dev, "failed to submit urb: %d\n", ret);
                goto out;
        }

        ret = iguanair_get_features(ir);
        if (ret)
                goto out2;

        snprintf(ir->name, sizeof(ir->name),
                "IguanaWorks USB IR Transceiver version 0x%04x", ir->version);

        usb_make_path(ir->udev, ir->phys, sizeof(ir->phys));

        rc->device_name = ir->name;
        rc->input_phys = ir->phys;
        usb_to_input_id(ir->udev, &rc->input_id);
        rc->dev.parent = &intf->dev;
        rc->allowed_protocols = RC_PROTO_BIT_ALL_IR_DECODER;
        rc->priv = ir;
        rc->open = iguanair_open;
        rc->close = iguanair_close;
        rc->s_tx_mask = iguanair_set_tx_mask;
        rc->s_tx_carrier = iguanair_set_tx_carrier;
        rc->tx_ir = iguanair_tx;
        rc->driver_name = DRIVER_NAME;
        rc->map_name = RC_MAP_RC6_MCE;
        rc->min_timeout = 1;
        rc->timeout = IR_DEFAULT_TIMEOUT;
        rc->max_timeout = 10 * IR_DEFAULT_TIMEOUT;
        rc->rx_resolution = RX_RESOLUTION;

        iguanair_set_tx_carrier(rc, 38000);
        iguanair_set_tx_mask(rc, 0);

        ret = rc_register_device(rc);
        if (ret < 0) {
                dev_err(&intf->dev, "failed to register rc device %d", ret);
                goto out2;
        }

        usb_set_intfdata(intf, ir);

        return 0;
out2:
        usb_kill_urb(ir->urb_in);
        usb_kill_urb(ir->urb_out);
out:
        if (ir) {
                usb_free_urb(ir->urb_in);
                usb_free_urb(ir->urb_out);
                usb_free_coherent(udev, MAX_IN_PACKET, ir->buf_in, ir->dma_in);
                usb_free_coherent(udev, MAX_OUT_PACKET, ir->packet,
                                                                ir->dma_out);
        }
        rc_free_device(rc);
        kfree(ir);
        return ret;
}

static void iguanair_disconnect(struct usb_interface *intf)
{
        struct iguanair *ir = usb_get_intfdata(intf);

        rc_unregister_device(ir->rc);
        usb_set_intfdata(intf, NULL);
        usb_kill_urb(ir->urb_in);
        usb_kill_urb(ir->urb_out);
        usb_free_urb(ir->urb_in);
        usb_free_urb(ir->urb_out);
        usb_free_coherent(ir->udev, MAX_IN_PACKET, ir->buf_in, ir->dma_in);
        usb_free_coherent(ir->udev, MAX_OUT_PACKET, ir->packet, ir->dma_out);
        kfree(ir);
}

static int iguanair_suspend(struct usb_interface *intf, pm_message_t message)
{
        struct iguanair *ir = usb_get_intfdata(intf);
        int rc = 0;

        mutex_lock(&ir->lock);

        if (ir->receiver_on) {
                rc = iguanair_receiver(ir, false);
                if (rc)
                        dev_warn(ir->dev, "failed to disable receiver for suspend\n");
        }

        usb_kill_urb(ir->urb_in);
        usb_kill_urb(ir->urb_out);

        mutex_unlock(&ir->lock);

        return rc;
}

static int iguanair_resume(struct usb_interface *intf)
{
        struct iguanair *ir = usb_get_intfdata(intf);
        int rc = 0;

        mutex_lock(&ir->lock);

        rc = usb_submit_urb(ir->urb_in, GFP_KERNEL);
        if (rc)
                dev_warn(&intf->dev, "failed to submit urb: %d\n", rc);

        if (ir->receiver_on) {
                rc = iguanair_receiver(ir, true);
                if (rc)
                        dev_warn(ir->dev, "failed to enable receiver after resume\n");
        }

        mutex_unlock(&ir->lock);

        return rc;
}

static const struct usb_device_id iguanair_table[] = {
        { USB_DEVICE(0x1781, 0x0938) },
        { }
};

static struct usb_driver iguanair_driver = {
        .name = DRIVER_NAME,
        .probe = iguanair_probe,
        .disconnect = iguanair_disconnect,
        .suspend = iguanair_suspend,
        .resume = iguanair_resume,
        .reset_resume = iguanair_resume,
        .id_table = iguanair_table,
        .soft_unbind = 1        /* we want to disable receiver on unbind */
};

module_usb_driver(iguanair_driver);

MODULE_DESCRIPTION("IguanaWorks USB IR Transceiver");
MODULE_AUTHOR("Sean Young <sean@mess.org>");
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(usb, iguanair_table);