/*
 * atusb.c - Driver for the ATUSB IEEE 802.15.4 dongle
 *
 * Written 2013 by Werner Almesberger <werner@almesberger.net>
 *
 * Copyright (c) 2015 - 2016 Stefan Schmidt <stefan@datenfreihafen.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, version 2
 *
 * Based on at86rf230.c and spi_atusb.c.
 * at86rf230.c is
 * Copyright (C) 2009 Siemens AG
 * Written by: Dmitry Eremin-Solenikov <dmitry.baryshkov@siemens.com>
 *
 * spi_atusb.c is
 * Copyright (c) 2011 Richard Sharpe <realrichardsharpe@gmail.com>
 * Copyright (c) 2011 Stefan Schmidt <stefan@datenfreihafen.org>
 * Copyright (c) 2011 Werner Almesberger <werner@almesberger.net>
 *
 * USB initialization is
 * Copyright (c) 2013 Alexander Aring <alex.aring@gmail.com>
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/jiffies.h>
#include <linux/usb.h>
#include <linux/skbuff.h>

#include <net/cfg802154.h>
#include <net/mac802154.h>

#include "at86rf230.h"
#include "atusb.h"

#define ATUSB_JEDEC_ATMEL       0x1f    /* JEDEC manufacturer ID */

#define ATUSB_NUM_RX_URBS       4       /* allow for a bit of local latency */
#define ATUSB_ALLOC_DELAY_MS    100     /* delay after failed allocation */
#define ATUSB_TX_TIMEOUT_MS     200     /* on the air timeout */

struct atusb {
        struct ieee802154_hw *hw;
        struct usb_device *usb_dev;
        int shutdown;                   /* non-zero if shutting down */
        int err;                        /* set by first error */

        /* RX variables */
        struct delayed_work work;       /* memory allocations */
        struct usb_anchor idle_urbs;    /* URBs waiting to be submitted */
        struct usb_anchor rx_urbs;      /* URBs waiting for reception */

        /* TX variables */
        struct usb_ctrlrequest tx_dr;
        struct urb *tx_urb;
        struct sk_buff *tx_skb;
        uint8_t tx_ack_seq;             /* current TX ACK sequence number */
};

/* ----- USB commands without data ----------------------------------------- */

/* To reduce the number of error checks in the code, we record the first error
 * in atusb->err and reject all subsequent requests until the error is cleared.
 */

static int atusb_control_msg(struct atusb *atusb, unsigned int pipe,
                             __u8 request, __u8 requesttype,
                             __u16 value, __u16 index,
                             void *data, __u16 size, int timeout)
{
        struct usb_device *usb_dev = atusb->usb_dev;
        int ret;

        if (atusb->err)
                return atusb->err;

        ret = usb_control_msg(usb_dev, pipe, request, requesttype,
                              value, index, data, size, timeout);
        if (ret < 0) {
                atusb->err = ret;
                dev_err(&usb_dev->dev,
                        "atusb_control_msg: req 0x%02x val 0x%x idx 0x%x, error %d\n",
                        request, value, index, ret);
        }
        return ret;
}

static int atusb_command(struct atusb *atusb, uint8_t cmd, uint8_t arg)
{
        struct usb_device *usb_dev = atusb->usb_dev;

        dev_dbg(&usb_dev->dev, "atusb_command: cmd = 0x%x\n", cmd);
        return atusb_control_msg(atusb, usb_sndctrlpipe(usb_dev, 0),
                                 cmd, ATUSB_REQ_TO_DEV, arg, 0, NULL, 0, 1000);
}

static int atusb_write_reg(struct atusb *atusb, uint8_t reg, uint8_t value)
{
        struct usb_device *usb_dev = atusb->usb_dev;

        dev_dbg(&usb_dev->dev, "atusb_write_reg: 0x%02x <- 0x%02x\n",
                reg, value);
        return atusb_control_msg(atusb, usb_sndctrlpipe(usb_dev, 0),
                                 ATUSB_REG_WRITE, ATUSB_REQ_TO_DEV,
                                 value, reg, NULL, 0, 1000);
}

static int atusb_read_reg(struct atusb *atusb, uint8_t reg)
{
        struct usb_device *usb_dev = atusb->usb_dev;
        int ret;
        uint8_t value;

        dev_dbg(&usb_dev->dev, "atusb: reg = 0x%x\n", reg);
        ret = atusb_control_msg(atusb, usb_rcvctrlpipe(usb_dev, 0),
                                ATUSB_REG_READ, ATUSB_REQ_FROM_DEV,
                                0, reg, &value, 1, 1000);
        return ret >= 0 ? value : ret;
}

static int atusb_write_subreg(struct atusb *atusb, uint8_t reg, uint8_t mask,
                              uint8_t shift, uint8_t value)
{
        struct usb_device *usb_dev = atusb->usb_dev;
        uint8_t orig, tmp;
        int ret = 0;

        dev_dbg(&usb_dev->dev, "atusb_write_subreg: 0x%02x <- 0x%02x\n",
                reg, value);

        orig = atusb_read_reg(atusb, reg);

        /* Write the value only into that part of the register which is allowed
         * by the mask. All other bits stay as before.
         */
        tmp = orig & ~mask;
        tmp |= (value << shift) & mask;

        if (tmp != orig)
                ret = atusb_write_reg(atusb, reg, tmp);

        return ret;
}

static int atusb_get_and_clear_error(struct atusb *atusb)
{
        int err = atusb->err;

        atusb->err = 0;
        return err;
}

/* ----- skb allocation ---------------------------------------------------- */

#define MAX_PSDU        127
#define MAX_RX_XFER     (1 + MAX_PSDU + 2 + 1)  /* PHR+PSDU+CRC+LQI */

#define SKB_ATUSB(skb)  (*(struct atusb **)(skb)->cb)

static void atusb_in(struct urb *urb);

static int atusb_submit_rx_urb(struct atusb *atusb, struct urb *urb)
{
        struct usb_device *usb_dev = atusb->usb_dev;
        struct sk_buff *skb = urb->context;
        int ret;

        if (!skb) {
                skb = alloc_skb(MAX_RX_XFER, GFP_KERNEL);
                if (!skb) {
                        dev_warn_ratelimited(&usb_dev->dev,
                                             "atusb_in: can't allocate skb\n");
                        return -ENOMEM;
                }
                skb_put(skb, MAX_RX_XFER);
                SKB_ATUSB(skb) = atusb;
        }

        usb_fill_bulk_urb(urb, usb_dev, usb_rcvbulkpipe(usb_dev, 1),
                          skb->data, MAX_RX_XFER, atusb_in, skb);
        usb_anchor_urb(urb, &atusb->rx_urbs);

        ret = usb_submit_urb(urb, GFP_KERNEL);
        if (ret) {
                usb_unanchor_urb(urb);
                kfree_skb(skb);
                urb->context = NULL;
        }
        return ret;
}

static void atusb_work_urbs(struct work_struct *work)
{
        struct atusb *atusb =
            container_of(to_delayed_work(work), struct atusb, work);
        struct usb_device *usb_dev = atusb->usb_dev;
        struct urb *urb;
        int ret;

        if (atusb->shutdown)
                return;

        do {
                urb = usb_get_from_anchor(&atusb->idle_urbs);
                if (!urb)
                        return;
                ret = atusb_submit_rx_urb(atusb, urb);
        } while (!ret);

        usb_anchor_urb(urb, &atusb->idle_urbs);
        dev_warn_ratelimited(&usb_dev->dev,
                             "atusb_in: can't allocate/submit URB (%d)\n", ret);
        schedule_delayed_work(&atusb->work,
                              msecs_to_jiffies(ATUSB_ALLOC_DELAY_MS) + 1);
}

/* ----- Asynchronous USB -------------------------------------------------- */

static void atusb_tx_done(struct atusb *atusb, uint8_t seq)
{
        struct usb_device *usb_dev = atusb->usb_dev;
        uint8_t expect = atusb->tx_ack_seq;

        dev_dbg(&usb_dev->dev, "atusb_tx_done (0x%02x/0x%02x)\n", seq, expect);
        if (seq == expect) {
                /* TODO check for ifs handling in firmware */
                ieee802154_xmit_complete(atusb->hw, atusb->tx_skb, false);
        } else {
                /* TODO I experience this case when atusb has a tx complete
                 * irq before probing, we should fix the firmware it's an
                 * unlikely case now that seq == expect is then true, but can
                 * happen and fail with a tx_skb = NULL;
                 */
                ieee802154_wake_queue(atusb->hw);
                if (atusb->tx_skb)
                        dev_kfree_skb_irq(atusb->tx_skb);
        }
}

static void atusb_in_good(struct urb *urb)
{
        struct usb_device *usb_dev = urb->dev;
        struct sk_buff *skb = urb->context;
        struct atusb *atusb = SKB_ATUSB(skb);
        uint8_t len, lqi;

        if (!urb->actual_length) {
                dev_dbg(&usb_dev->dev, "atusb_in: zero-sized URB ?\n");
                return;
        }

        len = *skb->data;

        if (urb->actual_length == 1) {
                atusb_tx_done(atusb, len);
                return;
        }

        if (len + 1 > urb->actual_length - 1) {
                dev_dbg(&usb_dev->dev, "atusb_in: frame len %d+1 > URB %u-1\n",
                        len, urb->actual_length);
                return;
        }

        if (!ieee802154_is_valid_psdu_len(len)) {
                dev_dbg(&usb_dev->dev, "atusb_in: frame corrupted\n");
                return;
        }

        lqi = skb->data[len + 1];
        dev_dbg(&usb_dev->dev, "atusb_in: rx len %d lqi 0x%02x\n", len, lqi);
        skb_pull(skb, 1);       /* remove PHR */
        skb_trim(skb, len);     /* get payload only */
        ieee802154_rx_irqsafe(atusb->hw, skb, lqi);
        urb->context = NULL;    /* skb is gone */
}

static void atusb_in(struct urb *urb)
{
        struct usb_device *usb_dev = urb->dev;
        struct sk_buff *skb = urb->context;
        struct atusb *atusb = SKB_ATUSB(skb);

        dev_dbg(&usb_dev->dev, "atusb_in: status %d len %d\n",
                urb->status, urb->actual_length);
        if (urb->status) {
                if (urb->status == -ENOENT) { /* being killed */
                        kfree_skb(skb);
                        urb->context = NULL;
                        return;
                }
                dev_dbg(&usb_dev->dev, "atusb_in: URB error %d\n", urb->status);
        } else {
                atusb_in_good(urb);
        }

        usb_anchor_urb(urb, &atusb->idle_urbs);
        if (!atusb->shutdown)
                schedule_delayed_work(&atusb->work, 0);
}

/* ----- URB allocation/deallocation --------------------------------------- */

static void atusb_free_urbs(struct atusb *atusb)
{
        struct urb *urb;

        while (1) {
                urb = usb_get_from_anchor(&atusb->idle_urbs);
                if (!urb)
                        break;
                kfree_skb(urb->context);
                usb_free_urb(urb);
        }
}

static int atusb_alloc_urbs(struct atusb *atusb, int n)
{
        struct urb *urb;

        while (n) {
                urb = usb_alloc_urb(0, GFP_KERNEL);
                if (!urb) {
                        atusb_free_urbs(atusb);
                        return -ENOMEM;
                }
                usb_anchor_urb(urb, &atusb->idle_urbs);
                n--;
        }
        return 0;
}

/* ----- IEEE 802.15.4 interface operations -------------------------------- */

static void atusb_xmit_complete(struct urb *urb)
{
        dev_dbg(&urb->dev->dev, "atusb_xmit urb completed");
}

static int atusb_xmit(struct ieee802154_hw *hw, struct sk_buff *skb)
{
        struct atusb *atusb = hw->priv;
        struct usb_device *usb_dev = atusb->usb_dev;
        int ret;

        dev_dbg(&usb_dev->dev, "atusb_xmit (%d)\n", skb->len);
        atusb->tx_skb = skb;
        atusb->tx_ack_seq++;
        atusb->tx_dr.wIndex = cpu_to_le16(atusb->tx_ack_seq);
        atusb->tx_dr.wLength = cpu_to_le16(skb->len);

        usb_fill_control_urb(atusb->tx_urb, usb_dev,
                             usb_sndctrlpipe(usb_dev, 0),
                             (unsigned char *)&atusb->tx_dr, skb->data,
                             skb->len, atusb_xmit_complete, NULL);
        ret = usb_submit_urb(atusb->tx_urb, GFP_ATOMIC);
        dev_dbg(&usb_dev->dev, "atusb_xmit done (%d)\n", ret);
        return ret;
}

static int atusb_channel(struct ieee802154_hw *hw, u8 page, u8 channel)
{
        struct atusb *atusb = hw->priv;
        int ret;

        ret = atusb_write_subreg(atusb, SR_CHANNEL, channel);
        if (ret < 0)
                return ret;
        msleep(1);      /* @@@ ugly synchronization */
        return 0;
}

static int atusb_ed(struct ieee802154_hw *hw, u8 *level)
{
        BUG_ON(!level);
        *level = 0xbe;
        return 0;
}

static int atusb_set_hw_addr_filt(struct ieee802154_hw *hw,
                                  struct ieee802154_hw_addr_filt *filt,
                                  unsigned long changed)
{
        struct atusb *atusb = hw->priv;
        struct device *dev = &atusb->usb_dev->dev;

        if (changed & IEEE802154_AFILT_SADDR_CHANGED) {
                u16 addr = le16_to_cpu(filt->short_addr);

                dev_vdbg(dev, "atusb_set_hw_addr_filt called for saddr\n");
                atusb_write_reg(atusb, RG_SHORT_ADDR_0, addr);
                atusb_write_reg(atusb, RG_SHORT_ADDR_1, addr >> 8);
        }

        if (changed & IEEE802154_AFILT_PANID_CHANGED) {
                u16 pan = le16_to_cpu(filt->pan_id);

                dev_vdbg(dev, "atusb_set_hw_addr_filt called for pan id\n");
                atusb_write_reg(atusb, RG_PAN_ID_0, pan);
                atusb_write_reg(atusb, RG_PAN_ID_1, pan >> 8);
        }

        if (changed & IEEE802154_AFILT_IEEEADDR_CHANGED) {
                u8 i, addr[IEEE802154_EXTENDED_ADDR_LEN];

                memcpy(addr, &filt->ieee_addr, IEEE802154_EXTENDED_ADDR_LEN);
                dev_vdbg(dev, "atusb_set_hw_addr_filt called for IEEE addr\n");
                for (i = 0; i < 8; i++)
                        atusb_write_reg(atusb, RG_IEEE_ADDR_0 + i, addr[i]);
        }

        if (changed & IEEE802154_AFILT_PANC_CHANGED) {
                dev_vdbg(dev,
                         "atusb_set_hw_addr_filt called for panc change\n");
                if (filt->pan_coord)
                        atusb_write_subreg(atusb, SR_AACK_I_AM_COORD, 1);
                else
                        atusb_write_subreg(atusb, SR_AACK_I_AM_COORD, 0);
        }

        return atusb_get_and_clear_error(atusb);
}

static int atusb_start(struct ieee802154_hw *hw)
{
        struct atusb *atusb = hw->priv;
        struct usb_device *usb_dev = atusb->usb_dev;
        int ret;

        dev_dbg(&usb_dev->dev, "atusb_start\n");
        schedule_delayed_work(&atusb->work, 0);
        atusb_command(atusb, ATUSB_RX_MODE, 1);
        ret = atusb_get_and_clear_error(atusb);
        if (ret < 0)
                usb_kill_anchored_urbs(&atusb->idle_urbs);
        return ret;
}

static void atusb_stop(struct ieee802154_hw *hw)
{
        struct atusb *atusb = hw->priv;
        struct usb_device *usb_dev = atusb->usb_dev;

        dev_dbg(&usb_dev->dev, "atusb_stop\n");
        usb_kill_anchored_urbs(&atusb->idle_urbs);
        atusb_command(atusb, ATUSB_RX_MODE, 0);
        atusb_get_and_clear_error(atusb);
}

#define ATUSB_MAX_TX_POWERS 0xF
static const s32 atusb_powers[ATUSB_MAX_TX_POWERS + 1] = {
        300, 280, 230, 180, 130, 70, 0, -100, -200, -300, -400, -500, -700,
        -900, -1200, -1700,
};

static int
atusb_set_txpower(struct ieee802154_hw *hw, s32 mbm)
{
        struct atusb *atusb = hw->priv;
        u32 i;

        for (i = 0; i < hw->phy->supported.tx_powers_size; i++) {
                if (hw->phy->supported.tx_powers[i] == mbm)
                        return atusb_write_subreg(atusb, SR_TX_PWR_23X, i);
        }

        return -EINVAL;
}

#define ATUSB_MAX_ED_LEVELS 0xF
static const s32 atusb_ed_levels[ATUSB_MAX_ED_LEVELS + 1] = {
        -9100, -8900, -8700, -8500, -8300, -8100, -7900, -7700, -7500, -7300,
        -7100, -6900, -6700, -6500, -6300, -6100,
};

static int
atusb_set_cca_mode(struct ieee802154_hw *hw, const struct wpan_phy_cca *cca)
{
        struct atusb *atusb = hw->priv;
        u8 val;

        /* mapping 802.15.4 to driver spec */
        switch (cca->mode) {
        case NL802154_CCA_ENERGY:
                val = 1;
                break;
        case NL802154_CCA_CARRIER:
                val = 2;
                break;
        case NL802154_CCA_ENERGY_CARRIER:
                switch (cca->opt) {
                case NL802154_CCA_OPT_ENERGY_CARRIER_AND:
                        val = 3;
                        break;
                case NL802154_CCA_OPT_ENERGY_CARRIER_OR:
                        val = 0;
                        break;
                default:
                        return -EINVAL;
                }
                break;
        default:
                return -EINVAL;
        }

        return atusb_write_subreg(atusb, SR_CCA_MODE, val);
}

static int
atusb_set_cca_ed_level(struct ieee802154_hw *hw, s32 mbm)
{
        struct atusb *atusb = hw->priv;
        u32 i;

        for (i = 0; i < hw->phy->supported.cca_ed_levels_size; i++) {
                if (hw->phy->supported.cca_ed_levels[i] == mbm)
                        return atusb_write_subreg(atusb, SR_CCA_ED_THRES, i);
        }

        return -EINVAL;
}

static int
atusb_set_csma_params(struct ieee802154_hw *hw, u8 min_be, u8 max_be, u8 retries)
{
        struct atusb *atusb = hw->priv;
        int ret;

        ret = atusb_write_subreg(atusb, SR_MIN_BE, min_be);
        if (ret)
                return ret;

        ret = atusb_write_subreg(atusb, SR_MAX_BE, max_be);
        if (ret)
                return ret;

        return atusb_write_subreg(atusb, SR_MAX_CSMA_RETRIES, retries);
}

static int
atusb_set_promiscuous_mode(struct ieee802154_hw *hw, const bool on)
{
        struct atusb *atusb = hw->priv;
        int ret;

        if (on) {
                ret = atusb_write_subreg(atusb, SR_AACK_DIS_ACK, 1);
                if (ret < 0)
                        return ret;

                ret = atusb_write_subreg(atusb, SR_AACK_PROM_MODE, 1);
                if (ret < 0)
                        return ret;
        } else {
                ret = atusb_write_subreg(atusb, SR_AACK_PROM_MODE, 0);
                if (ret < 0)
                        return ret;

                ret = atusb_write_subreg(atusb, SR_AACK_DIS_ACK, 0);
                if (ret < 0)
                        return ret;
        }

        return 0;
}

static struct ieee802154_ops atusb_ops = {
        .owner                  = THIS_MODULE,
        .xmit_async             = atusb_xmit,
        .ed                     = atusb_ed,
        .set_channel            = atusb_channel,
        .start                  = atusb_start,
        .stop                   = atusb_stop,
        .set_hw_addr_filt       = atusb_set_hw_addr_filt,
        .set_txpower            = atusb_set_txpower,
        .set_cca_mode           = atusb_set_cca_mode,
        .set_cca_ed_level       = atusb_set_cca_ed_level,
        .set_csma_params        = atusb_set_csma_params,
        .set_promiscuous_mode   = atusb_set_promiscuous_mode,
};

/* ----- Firmware and chip version information ----------------------------- */

static int atusb_get_and_show_revision(struct atusb *atusb)
{
        struct usb_device *usb_dev = atusb->usb_dev;
        unsigned char buffer[3];
        int ret;

        /* Get a couple of the ATMega Firmware values */
        ret = atusb_control_msg(atusb, usb_rcvctrlpipe(usb_dev, 0),
                                ATUSB_ID, ATUSB_REQ_FROM_DEV, 0, 0,
                                buffer, 3, 1000);
        if (ret >= 0)
                dev_info(&usb_dev->dev,
                         "Firmware: major: %u, minor: %u, hardware type: %u\n",
                         buffer[0], buffer[1], buffer[2]);
        if (buffer[0] == 0 && buffer[1] < 2) {
                dev_info(&usb_dev->dev,
                         "Firmware version (%u.%u) is predates our first public release.",
                         buffer[0], buffer[1]);
                dev_info(&usb_dev->dev, "Please update to version 0.2 or newer");
        }

        return ret;
}

static int atusb_get_and_show_build(struct atusb *atusb)
{
        struct usb_device *usb_dev = atusb->usb_dev;
        char build[ATUSB_BUILD_SIZE + 1];
        int ret;

        ret = atusb_control_msg(atusb, usb_rcvctrlpipe(usb_dev, 0),
                                ATUSB_BUILD, ATUSB_REQ_FROM_DEV, 0, 0,
                                build, ATUSB_BUILD_SIZE, 1000);
        if (ret >= 0) {
                build[ret] = 0;
                dev_info(&usb_dev->dev, "Firmware: build %s\n", build);
        }

        return ret;
}

static int atusb_get_and_show_chip(struct atusb *atusb)
{
        struct usb_device *usb_dev = atusb->usb_dev;
        uint8_t man_id_0, man_id_1, part_num, version_num;
        const char *chip;

        man_id_0 = atusb_read_reg(atusb, RG_MAN_ID_0);
        man_id_1 = atusb_read_reg(atusb, RG_MAN_ID_1);
        part_num = atusb_read_reg(atusb, RG_PART_NUM);
        version_num = atusb_read_reg(atusb, RG_VERSION_NUM);

        if (atusb->err)
                return atusb->err;

        if ((man_id_1 << 8 | man_id_0) != ATUSB_JEDEC_ATMEL) {
                dev_err(&usb_dev->dev,
                        "non-Atmel transceiver xxxx%02x%02x\n",
                        man_id_1, man_id_0);
                goto fail;
        }

        switch (part_num) {
        case 2:
                chip = "AT86RF230";
                break;
        case 3:
                chip = "AT86RF231";
                break;
        default:
                dev_err(&usb_dev->dev,
                        "unexpected transceiver, part 0x%02x version 0x%02x\n",
                        part_num, version_num);
                goto fail;
        }

        dev_info(&usb_dev->dev, "ATUSB: %s version %d\n", chip, version_num);

        return 0;

fail:
        atusb->err = -ENODEV;
        return -ENODEV;
}

/* ----- Setup ------------------------------------------------------------- */

static int atusb_probe(struct usb_interface *interface,
                       const struct usb_device_id *id)
{
        struct usb_device *usb_dev = interface_to_usbdev(interface);
        struct ieee802154_hw *hw;
        struct atusb *atusb = NULL;
        int ret = -ENOMEM;

        hw = ieee802154_alloc_hw(sizeof(struct atusb), &atusb_ops);
        if (!hw)
                return -ENOMEM;

        atusb = hw->priv;
        atusb->hw = hw;
        atusb->usb_dev = usb_get_dev(usb_dev);
        usb_set_intfdata(interface, atusb);

        atusb->shutdown = 0;
        atusb->err = 0;
        INIT_DELAYED_WORK(&atusb->work, atusb_work_urbs);
        init_usb_anchor(&atusb->idle_urbs);
        init_usb_anchor(&atusb->rx_urbs);

        if (atusb_alloc_urbs(atusb, ATUSB_NUM_RX_URBS))
                goto fail;

        atusb->tx_dr.bRequestType = ATUSB_REQ_TO_DEV;
        atusb->tx_dr.bRequest = ATUSB_TX;
        atusb->tx_dr.wValue = cpu_to_le16(0);

        atusb->tx_urb = usb_alloc_urb(0, GFP_ATOMIC);
        if (!atusb->tx_urb)
                goto fail;

        hw->parent = &usb_dev->dev;
        hw->flags = IEEE802154_HW_TX_OMIT_CKSUM | IEEE802154_HW_AFILT |
                    IEEE802154_HW_PROMISCUOUS | IEEE802154_HW_CSMA_PARAMS;

        hw->phy->flags = WPAN_PHY_FLAG_TXPOWER | WPAN_PHY_FLAG_CCA_ED_LEVEL |
                         WPAN_PHY_FLAG_CCA_MODE;

        hw->phy->supported.cca_modes = BIT(NL802154_CCA_ENERGY) |
                BIT(NL802154_CCA_CARRIER) | BIT(NL802154_CCA_ENERGY_CARRIER);
        hw->phy->supported.cca_opts = BIT(NL802154_CCA_OPT_ENERGY_CARRIER_AND) |
                BIT(NL802154_CCA_OPT_ENERGY_CARRIER_OR);

        hw->phy->supported.cca_ed_levels = atusb_ed_levels;
        hw->phy->supported.cca_ed_levels_size = ARRAY_SIZE(atusb_ed_levels);

        hw->phy->cca.mode = NL802154_CCA_ENERGY;

        hw->phy->current_page = 0;
        hw->phy->current_channel = 11;  /* reset default */
        hw->phy->supported.channels[0] = 0x7FFF800;
        hw->phy->supported.tx_powers = atusb_powers;
        hw->phy->supported.tx_powers_size = ARRAY_SIZE(atusb_powers);
        hw->phy->transmit_power = hw->phy->supported.tx_powers[0];
        ieee802154_random_extended_addr(&hw->phy->perm_extended_addr);
        hw->phy->cca_ed_level = hw->phy->supported.cca_ed_levels[7];

        atusb_command(atusb, ATUSB_RF_RESET, 0);
        atusb_get_and_show_chip(atusb);
        atusb_get_and_show_revision(atusb);
        atusb_get_and_show_build(atusb);
        ret = atusb_get_and_clear_error(atusb);
        if (ret) {
                dev_err(&atusb->usb_dev->dev,
                        "%s: initialization failed, error = %d\n",
                        __func__, ret);
                goto fail;
        }

        ret = ieee802154_register_hw(hw);
        if (ret)
                goto fail;

        /* If we just powered on, we're now in P_ON and need to enter TRX_OFF
         * explicitly. Any resets after that will send us straight to TRX_OFF,
         * making the command below redundant.
         */
        atusb_write_reg(atusb, RG_TRX_STATE, STATE_FORCE_TRX_OFF);
        msleep(1);      /* reset => TRX_OFF, tTR13 = 37 us */

#if 0
        /* Calculating the maximum time available to empty the frame buffer
         * on reception:
         *
         * According to [1], the inter-frame gap is
         * R * 20 * 16 us + 128 us
         * where R is a random number from 0 to 7. Furthermore, we have 20 bit
         * times (80 us at 250 kbps) of SHR of the next frame before the
         * transceiver begins storing data in the frame buffer.
         *
         * This yields a minimum time of 208 us between the last data of a
         * frame and the first data of the next frame. This time is further
         * reduced by interrupt latency in the atusb firmware.
         *
         * atusb currently needs about 500 us to retrieve a maximum-sized
         * frame. We therefore have to allow reception of a new frame to begin
         * while we retrieve the previous frame.
         *
         * [1] "JN-AN-1035 Calculating data rates in an IEEE 802.15.4-based
         *      network", Jennic 2006.
         *     http://www.jennic.com/download_file.php?supportFile=JN-AN-1035%20Calculating%20802-15-4%20Data%20Rates-1v0.pdf
         */

        atusb_write_subreg(atusb, SR_RX_SAFE_MODE, 1);
#endif
        atusb_write_reg(atusb, RG_IRQ_MASK, 0xff);

        ret = atusb_get_and_clear_error(atusb);
        if (!ret)
                return 0;

        dev_err(&atusb->usb_dev->dev,
                "%s: setup failed, error = %d\n",
                __func__, ret);

        ieee802154_unregister_hw(hw);
fail:
        atusb_free_urbs(atusb);
        usb_kill_urb(atusb->tx_urb);
        usb_free_urb(atusb->tx_urb);
        usb_put_dev(usb_dev);
        ieee802154_free_hw(hw);
        return ret;
}

static void atusb_disconnect(struct usb_interface *interface)
{
        struct atusb *atusb = usb_get_intfdata(interface);

        dev_dbg(&atusb->usb_dev->dev, "atusb_disconnect\n");

        atusb->shutdown = 1;
        cancel_delayed_work_sync(&atusb->work);

        usb_kill_anchored_urbs(&atusb->rx_urbs);
        atusb_free_urbs(atusb);
        usb_kill_urb(atusb->tx_urb);
        usb_free_urb(atusb->tx_urb);

        ieee802154_unregister_hw(atusb->hw);

        ieee802154_free_hw(atusb->hw);

        usb_set_intfdata(interface, NULL);
        usb_put_dev(atusb->usb_dev);

        pr_debug("atusb_disconnect done\n");
}

/* The devices we work with */
static const struct usb_device_id atusb_device_table[] = {
        {
                .match_flags            = USB_DEVICE_ID_MATCH_DEVICE |
                                          USB_DEVICE_ID_MATCH_INT_INFO,
                .idVendor               = ATUSB_VENDOR_ID,
                .idProduct              = ATUSB_PRODUCT_ID,
                .bInterfaceClass        = USB_CLASS_VENDOR_SPEC
        },
        /* end with null element */
        {}
};
MODULE_DEVICE_TABLE(usb, atusb_device_table);

static struct usb_driver atusb_driver = {
        .name           = "atusb",
        .probe          = atusb_probe,
        .disconnect     = atusb_disconnect,
        .id_table       = atusb_device_table,
};
module_usb_driver(atusb_driver);

MODULE_AUTHOR("Alexander Aring <alex.aring@gmail.com>");
MODULE_AUTHOR("Richard Sharpe <realrichardsharpe@gmail.com>");
MODULE_AUTHOR("Stefan Schmidt <stefan@datenfreihafen.org>");
MODULE_AUTHOR("Werner Almesberger <werner@almesberger.net>");
MODULE_DESCRIPTION("ATUSB IEEE 802.15.4 Driver");
MODULE_LICENSE("GPL");