text: // SPDX-License-Identifier: GPL-2.0-or-later
  /* ZD1211 USB-WLAN driver for Linux
   *
   * Copyright (C) 2005-2007 Ulrich Kunitz <kune@deine-taler.de>
   * Copyright (C) 2006-2007 Daniel Drake <dsd@gentoo.org>
   * Copyright (C) 2006-2007 Michael Wu <flamingice@sourmilk.net>
   */
  
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/firmware.h>
  #include <linux/device.h>
  #include <linux/errno.h>
  #include <linux/slab.h>
  #include <linux/skbuff.h>
  #include <linux/usb.h>
  #include <linux/workqueue.h>
  #include <linux/module.h>
  #include <net/mac80211.h>
  #include <asm/unaligned.h>
  
  #include "zd_def.h"
  #include "zd_mac.h"
  #include "zd_usb.h"
  
  static const struct usb_device_id usb_ids[] = {
  	/* ZD1211 */
  	{ USB_DEVICE(0x0105, 0x145f), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x0586, 0x3401), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x0586, 0x3402), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x0586, 0x3407), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x0586, 0x3409), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x079b, 0x004a), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x07b8, 0x6001), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x0ace, 0x1211), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x0ace, 0xa211), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x0b05, 0x170c), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x0b3b, 0x1630), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x0b3b, 0x5630), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x0df6, 0x9071), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x0df6, 0x9075), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x126f, 0xa006), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x129b, 0x1666), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x13b1, 0x001e), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x1435, 0x0711), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x14ea, 0xab10), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x14ea, 0xab13), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x157e, 0x300a), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x157e, 0x300b), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x157e, 0x3204), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x157e, 0x3207), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x1740, 0x2000), .driver_info = DEVICE_ZD1211 },
  	{ USB_DEVICE(0x6891, 0xa727), .driver_info = DEVICE_ZD1211 },
  	/* ZD1211B */
  	{ USB_DEVICE(0x0053, 0x5301), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0409, 0x0248), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0411, 0x00da), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0471, 0x1236), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0471, 0x1237), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x050d, 0x705c), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x054c, 0x0257), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0586, 0x340a), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0586, 0x340f), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0586, 0x3410), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0586, 0x3412), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0586, 0x3413), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x079b, 0x0062), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x07b8, 0x6001), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x07fa, 0x1196), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x083a, 0x4505), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x083a, 0xe501), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x083a, 0xe503), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x083a, 0xe506), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0ace, 0x1215), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0ace, 0xb215), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0b05, 0x171b), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0baf, 0x0121), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0cde, 0x001a), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x0df6, 0x0036), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x129b, 0x1667), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x13b1, 0x0024), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x157e, 0x300d), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x1582, 0x6003), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x2019, 0x5303), .driver_info = DEVICE_ZD1211B },
  	{ USB_DEVICE(0x2019, 0xed01), .driver_info = DEVICE_ZD1211B },
  	/* "Driverless" devices that need ejecting */
  	{ USB_DEVICE(0x0ace, 0x2011), .driver_info = DEVICE_INSTALLER },
  	{ USB_DEVICE(0x0ace, 0x20ff), .driver_info = DEVICE_INSTALLER },
  	{}
  };
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("USB driver for devices with the ZD1211 chip.");
  MODULE_AUTHOR("Ulrich Kunitz");
  MODULE_AUTHOR("Daniel Drake");
  MODULE_VERSION("1.0");
  MODULE_DEVICE_TABLE(usb, usb_ids);
  
  #define FW_ZD1211_PREFIX	"zd1211/zd1211_"
  #define FW_ZD1211B_PREFIX	"zd1211/zd1211b_"
  
  static bool check_read_regs(struct zd_usb *usb, struct usb_req_read_regs *req,
  			    unsigned int count);
  
  /* USB device initialization */
  static void int_urb_complete(struct urb *urb);
  
  static int request_fw_file(
  	const struct firmware **fw, const char *name, struct device *device)
  {
  	int r;
  
  	dev_dbg_f(device, "fw name %s\n", name);
  
  	r = request_firmware(fw, name, device);
  	if (r)
  		dev_err(device,
  		       "Could not load firmware file %s. Error number %d\n",
  		       name, r);
  	return r;
  }
  
  static inline u16 get_bcdDevice(const struct usb_device *udev)
  {
  	return le16_to_cpu(udev->descriptor.bcdDevice);
  }
  
  enum upload_code_flags {
  	REBOOT = 1,
  };
  
  /* Ensures that MAX_TRANSFER_SIZE is even. */
  #define MAX_TRANSFER_SIZE (USB_MAX_TRANSFER_SIZE & ~1)
  
  static int upload_code(struct usb_device *udev,
  	const u8 *data, size_t size, u16 code_offset, int flags)
  {
  	u8 *p;
  	int r;
  
  	/* USB request blocks need "kmalloced" buffers.
  	 */
  	p = kmalloc(MAX_TRANSFER_SIZE, GFP_KERNEL);
  	if (!p) {
  		r = -ENOMEM;
  		goto error;
  	}
  
  	size &= ~1;
  	while (size > 0) {
  		size_t transfer_size = size <= MAX_TRANSFER_SIZE ?
  			size : MAX_TRANSFER_SIZE;
  
  		dev_dbg_f(&udev->dev, "transfer size %zu\n", transfer_size);
  
  		memcpy(p, data, transfer_size);
  		r = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
  			USB_REQ_FIRMWARE_DOWNLOAD,
  			USB_DIR_OUT | USB_TYPE_VENDOR,
  			code_offset, 0, p, transfer_size, 1000 /* ms */);
  		if (r < 0) {
  			dev_err(&udev->dev,
  			       "USB control request for firmware upload"
  			       " failed. Error number %d\n", r);
  			goto error;
  		}
  		transfer_size = r & ~1;
  
  		size -= transfer_size;
  		data += transfer_size;
  		code_offset += transfer_size/sizeof(u16);
  	}
  
  	if (flags & REBOOT) {
  		u8 ret;
  
  		/* Use "DMA-aware" buffer. */
  		r = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
  			USB_REQ_FIRMWARE_CONFIRM,
  			USB_DIR_IN | USB_TYPE_VENDOR,
  			0, 0, p, sizeof(ret), 5000 /* ms */);
  		if (r != sizeof(ret)) {
  			dev_err(&udev->dev,
  				"control request firmware confirmation failed."
  				" Return value %d\n", r);
  			if (r >= 0)
  				r = -ENODEV;
  			goto error;
  		}
  		ret = p[0];
  		if (ret & 0x80) {
  			dev_err(&udev->dev,
  				"Internal error while downloading."
  				" Firmware confirm return value %#04x\n",
  				(unsigned int)ret);
  			r = -ENODEV;
  			goto error;
  		}
  		dev_dbg_f(&udev->dev, "firmware confirm return value %#04x\n",
  			(unsigned int)ret);
  	}
  
  	r = 0;
  error:
  	kfree(p);
  	return r;
  }
  
  static u16 get_word(const void *data, u16 offset)
  {
  	const __le16 *p = data;
  	return le16_to_cpu(p[offset]);
  }
  
  static char *get_fw_name(struct zd_usb *usb, char *buffer, size_t size,
  	               const char* postfix)
  {
  	scnprintf(buffer, size, "%s%s",
  		usb->is_zd1211b ?
  			FW_ZD1211B_PREFIX : FW_ZD1211_PREFIX,
  		postfix);
  	return buffer;
  }
  
  static int handle_version_mismatch(struct zd_usb *usb,
  	const struct firmware *ub_fw)
  {
  	struct usb_device *udev = zd_usb_to_usbdev(usb);
  	const struct firmware *ur_fw = NULL;
  	int offset;
  	int r = 0;
  	char fw_name[128];
  
  	r = request_fw_file(&ur_fw,
  		get_fw_name(usb, fw_name, sizeof(fw_name), "ur"),
  		&udev->dev);
  	if (r)
  		goto error;
  
  	r = upload_code(udev, ur_fw->data, ur_fw->size, FW_START, REBOOT);
  	if (r)
  		goto error;
  
  	offset = (E2P_BOOT_CODE_OFFSET * sizeof(u16));
  	r = upload_code(udev, ub_fw->data + offset, ub_fw->size - offset,
  		E2P_START + E2P_BOOT_CODE_OFFSET, REBOOT);
  
  	/* At this point, the vendor driver downloads the whole firmware
  	 * image, hacks around with version IDs, and uploads it again,
  	 * completely overwriting the boot code. We do not do this here as
  	 * it is not required on any tested devices, and it is suspected to
  	 * cause problems. */
  error:
  	release_firmware(ur_fw);
  	return r;
  }
  
  static int upload_firmware(struct zd_usb *usb)
  {
  	int r;
  	u16 fw_bcdDevice;
  	u16 bcdDevice;
  	struct usb_device *udev = zd_usb_to_usbdev(usb);
  	const struct firmware *ub_fw = NULL;
  	const struct firmware *uph_fw = NULL;
  	char fw_name[128];
  
  	bcdDevice = get_bcdDevice(udev);
  
  	r = request_fw_file(&ub_fw,
  		get_fw_name(usb, fw_name, sizeof(fw_name), "ub"),
  		&udev->dev);
  	if (r)
  		goto error;
  
  	fw_bcdDevice = get_word(ub_fw->data, E2P_DATA_OFFSET);
  
  	if (fw_bcdDevice != bcdDevice) {
  		dev_info(&udev->dev,
  			"firmware version %#06x and device bootcode version "
  			"%#06x differ\n", fw_bcdDevice, bcdDevice);
  		if (bcdDevice <= 0x4313)
  			dev_warn(&udev->dev, "device has old bootcode, please "
  				"report success or failure\n");
  
  		r = handle_version_mismatch(usb, ub_fw);
  		if (r)
  			goto error;
  	} else {
  		dev_dbg_f(&udev->dev,
  			"firmware device id %#06x is equal to the "
  			"actual device id\n", fw_bcdDevice);
  	}
  
  
  	r = request_fw_file(&uph_fw,
  		get_fw_name(usb, fw_name, sizeof(fw_name), "uphr"),
  		&udev->dev);
  	if (r)
  		goto error;
  
  	r = upload_code(udev, uph_fw->data, uph_fw->size, FW_START, REBOOT);
  	if (r) {
  		dev_err(&udev->dev,
  			"Could not upload firmware code uph. Error number %d\n",
  			r);
  	}
  
  	/* FALL-THROUGH */
  error:
  	release_firmware(ub_fw);
  	release_firmware(uph_fw);
  	return r;
  }
  
  MODULE_FIRMWARE(FW_ZD1211B_PREFIX "ur");
  MODULE_FIRMWARE(FW_ZD1211_PREFIX "ur");
  MODULE_FIRMWARE(FW_ZD1211B_PREFIX "ub");
  MODULE_FIRMWARE(FW_ZD1211_PREFIX "ub");
  MODULE_FIRMWARE(FW_ZD1211B_PREFIX "uphr");
  MODULE_FIRMWARE(FW_ZD1211_PREFIX "uphr");
  
  /* Read data from device address space using "firmware interface" which does
   * not require firmware to be loaded. */
  int zd_usb_read_fw(struct zd_usb *usb, zd_addr_t addr, u8 *data, u16 len)
  {
  	int r;
  	struct usb_device *udev = zd_usb_to_usbdev(usb);
  	u8 *buf;
  
  	/* Use "DMA-aware" buffer. */
  	buf = kmalloc(len, GFP_KERNEL);
  	if (!buf)
  		return -ENOMEM;
  	r = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
  		USB_REQ_FIRMWARE_READ_DATA, USB_DIR_IN | 0x40, addr, 0,
  		buf, len, 5000);
  	if (r < 0) {
  		dev_err(&udev->dev,
  			"read over firmware interface failed: %d\n", r);
  		goto exit;
  	} else if (r != len) {
  		dev_err(&udev->dev,
  			"incomplete read over firmware interface: %d/%d\n",
  			r, len);
  		r = -EIO;
  		goto exit;
  	}
  	r = 0;
  	memcpy(data, buf, len);
  exit:
  	kfree(buf);
  	return r;
  }
  
  #define urb_dev(urb) (&(urb)->dev->dev)
  
  static inline void handle_regs_int_override(struct urb *urb)
  {
  	struct zd_usb *usb = urb->context;
  	struct zd_usb_interrupt *intr = &usb->intr;
  	unsigned long flags;
  
  	spin_lock_irqsave(&intr->lock, flags);
  	if (atomic_read(&intr->read_regs_enabled)) {
  		atomic_set(&intr->read_regs_enabled, 0);
  		intr->read_regs_int_overridden = 1;
  		complete(&intr->read_regs.completion);
  	}
  	spin_unlock_irqrestore(&intr->lock, flags);
  }
  
  static inline void handle_regs_int(struct urb *urb)
  {
  	struct zd_usb *usb = urb->context;
  	struct zd_usb_interrupt *intr = &usb->intr;
  	unsigned long flags;
  	int len;
  	u16 int_num;
  
  	ZD_ASSERT(in_interrupt());
  	spin_lock_irqsave(&intr->lock, flags);
  
  	int_num = le16_to_cpu(*(__le16 *)(urb->transfer_buffer+2));
  	if (int_num == CR_INTERRUPT) {
  		struct zd_mac *mac = zd_hw_mac(zd_usb_to_hw(urb->context));
  		spin_lock(&mac->lock);
  		memcpy(&mac->intr_buffer, urb->transfer_buffer,
  				USB_MAX_EP_INT_BUFFER);
  		spin_unlock(&mac->lock);
  		schedule_work(&mac->process_intr);
  	} else if (atomic_read(&intr->read_regs_enabled)) {
  		len = urb->actual_length;
  		intr->read_regs.length = urb->actual_length;
  		if (len > sizeof(intr->read_regs.buffer))
  			len = sizeof(intr->read_regs.buffer);
  
  		memcpy(intr->read_regs.buffer, urb->transfer_buffer, len);
  
  		/* Sometimes USB_INT_ID_REGS is not overridden, but comes after
  		 * USB_INT_ID_RETRY_FAILED. Read-reg retry then gets this
  		 * delayed USB_INT_ID_REGS, but leaves USB_INT_ID_REGS of
  		 * retry unhandled. Next read-reg command then might catch
  		 * this wrong USB_INT_ID_REGS. Fix by ignoring wrong reads.
  		 */
  		if (!check_read_regs(usb, intr->read_regs.req,
  						intr->read_regs.req_count))
  			goto out;
  
  		atomic_set(&intr->read_regs_enabled, 0);
  		intr->read_regs_int_overridden = 0;
  		complete(&intr->read_regs.completion);
  
  		goto out;
  	}
  
  out:
  	spin_unlock_irqrestore(&intr->lock, flags);
  
  	/* CR_INTERRUPT might override read_reg too. */
  	if (int_num == CR_INTERRUPT && atomic_read(&intr->read_regs_enabled))
  		handle_regs_int_override(urb);
  }
  
  static void int_urb_complete(struct urb *urb)
  {
  	int r;
  	struct usb_int_header *hdr;
  	struct zd_usb *usb;
  	struct zd_usb_interrupt *intr;
  
  	switch (urb->status) {
  	case 0:
  		break;
  	case -ESHUTDOWN:
  	case -EINVAL:
  	case -ENODEV:
  	case -ENOENT:
  	case -ECONNRESET:
  	case -EPIPE:
  		dev_dbg_f(urb_dev(urb), "urb %p error %d\n", urb, urb->status);
  		return;
  	default:
  		dev_dbg_f(urb_dev(urb), "urb %p error %d\n", urb, urb->status);
  		goto resubmit;
  	}
  
  	if (urb->actual_length < sizeof(hdr)) {
  		dev_dbg_f(urb_dev(urb), "error: urb %p to small\n", urb);
  		goto resubmit;
  	}
  
  	hdr = urb->transfer_buffer;
  	if (hdr->type != USB_INT_TYPE) {
  		dev_dbg_f(urb_dev(urb), "error: urb %p wrong type\n", urb);
  		goto resubmit;
  	}
  
  	/* USB_INT_ID_RETRY_FAILED triggered by tx-urb submit can override
  	 * pending USB_INT_ID_REGS causing read command timeout.
  	 */
  	usb = urb->context;
  	intr = &usb->intr;
  	if (hdr->id != USB_INT_ID_REGS && atomic_read(&intr->read_regs_enabled))
  		handle_regs_int_override(urb);
  
  	switch (hdr->id) {
  	case USB_INT_ID_REGS:
  		handle_regs_int(urb);
  		break;
  	case USB_INT_ID_RETRY_FAILED:
  		zd_mac_tx_failed(urb);
  		break;
  	default:
  		dev_dbg_f(urb_dev(urb), "error: urb %p unknown id %x\n", urb,
  			(unsigned int)hdr->id);
  		goto resubmit;
  	}
  
  resubmit:
  	r = usb_submit_urb(urb, GFP_ATOMIC);
  	if (r) {
  		dev_dbg_f(urb_dev(urb), "error: resubmit urb %p err code %d\n",
  			  urb, r);
  		/* TODO: add worker to reset intr->urb */
  	}
  	return;
  }
  
  static inline int int_urb_interval(struct usb_device *udev)
  {
  	switch (udev->speed) {
  	case USB_SPEED_HIGH:
  		return 4;
  	case USB_SPEED_LOW:
  		return 10;
  	case USB_SPEED_FULL:
  	default:
  		return 1;
  	}
  }
  
  static inline int usb_int_enabled(struct zd_usb *usb)
  {
  	unsigned long flags;
  	struct zd_usb_interrupt *intr = &usb->intr;
  	struct urb *urb;
  
  	spin_lock_irqsave(&intr->lock, flags);
  	urb = intr->urb;
  	spin_unlock_irqrestore(&intr->lock, flags);
  	return urb != NULL;
  }
  
  int zd_usb_enable_int(struct zd_usb *usb)
  {
  	int r;
  	struct usb_device *udev = zd_usb_to_usbdev(usb);
  	struct zd_usb_interrupt *intr = &usb->intr;
  	struct urb *urb;
  
  	dev_dbg_f(zd_usb_dev(usb), "\n");
  
  	urb = usb_alloc_urb(0, GFP_KERNEL);
  	if (!urb) {
  		r = -ENOMEM;
  		goto out;
  	}
  
  	ZD_ASSERT(!irqs_disabled());
  	spin_lock_irq(&intr->lock);
  	if (intr->urb) {
  		spin_unlock_irq(&intr->lock);
  		r = 0;
  		goto error_free_urb;
  	}
  	intr->urb = urb;
  	spin_unlock_irq(&intr->lock);
  
  	r = -ENOMEM;
  	intr->buffer = usb_alloc_coherent(udev, USB_MAX_EP_INT_BUFFER,
  					  GFP_KERNEL, &intr->buffer_dma);
  	if (!intr->buffer) {
  		dev_dbg_f(zd_usb_dev(usb),
  			"couldn't allocate transfer_buffer\n");
  		goto error_set_urb_null;
  	}
  
  	usb_fill_int_urb(urb, udev, usb_rcvintpipe(udev, EP_INT_IN),
  			 intr->buffer, USB_MAX_EP_INT_BUFFER,
  			 int_urb_complete, usb,
  			 intr->interval);
  	urb->transfer_dma = intr->buffer_dma;
  	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
  
  	dev_dbg_f(zd_usb_dev(usb), "submit urb %p\n", intr->urb);
  	r = usb_submit_urb(urb, GFP_KERNEL);
  	if (r) {
  		dev_dbg_f(zd_usb_dev(usb),
  			 "Couldn't submit urb. Error number %d\n", r);
  		goto error;
  	}
  
  	return 0;
  error:
  	usb_free_coherent(udev, USB_MAX_EP_INT_BUFFER,
  			  intr->buffer, intr->buffer_dma);
  error_set_urb_null:
  	spin_lock_irq(&intr->lock);
  	intr->urb = NULL;
  	spin_unlock_irq(&intr->lock);
  error_free_urb:
  	usb_free_urb(urb);
  out:
  	return r;
  }
  
  void zd_usb_disable_int(struct zd_usb *usb)
  {
  	unsigned long flags;
  	struct usb_device *udev = zd_usb_to_usbdev(usb);
  	struct zd_usb_interrupt *intr = &usb->intr;
  	struct urb *urb;
  	void *buffer;
  	dma_addr_t buffer_dma;
  
  	spin_lock_irqsave(&intr->lock, flags);
  	urb = intr->urb;
  	if (!urb) {
  		spin_unlock_irqrestore(&intr->lock, flags);
  		return;
  	}
  	intr->urb = NULL;
  	buffer = intr->buffer;
  	buffer_dma = intr->buffer_dma;
  	intr->buffer = NULL;
  	spin_unlock_irqrestore(&intr->lock, flags);
  
  	usb_kill_urb(urb);
  	dev_dbg_f(zd_usb_dev(usb), "urb %p killed\n", urb);
  	usb_free_urb(urb);
  
  	if (buffer)
  		usb_free_coherent(udev, USB_MAX_EP_INT_BUFFER,
  				  buffer, buffer_dma);
  }
  
  static void handle_rx_packet(struct zd_usb *usb, const u8 *buffer,
  			     unsigned int length)
  {
  	int i;
  	const struct rx_length_info *length_info;
  
  	if (length < sizeof(struct rx_length_info)) {
  		/* It's not a complete packet anyhow. */
  		dev_dbg_f(zd_usb_dev(usb), "invalid, small RX packet : %d\n",
  					   length);
  		return;
  	}
  	length_info = (struct rx_length_info *)
  		(buffer + length - sizeof(struct rx_length_info));
  
  	/* It might be that three frames are merged into a single URB
  	 * transaction. We have to check for the length info tag.
  	 *
  	 * While testing we discovered that length_info might be unaligned,
  	 * because if USB transactions are merged, the last packet will not
  	 * be padded. Unaligned access might also happen if the length_info
  	 * structure is not present.
  	 */
  	if (get_unaligned_le16(&length_info->tag) == RX_LENGTH_INFO_TAG)
  	{
  		unsigned int l, k, n;
  		for (i = 0, l = 0;; i++) {
  			k = get_unaligned_le16(&length_info->length[i]);
  			if (k == 0)
  				return;
  			n = l+k;
  			if (n > length)
  				return;
  			zd_mac_rx(zd_usb_to_hw(usb), buffer+l, k);
  			if (i >= 2)
  				return;
  			l = (n+3) & ~3;
  		}
  	} else {
  		zd_mac_rx(zd_usb_to_hw(usb), buffer, length);
  	}
  }
  
  static void rx_urb_complete(struct urb *urb)
  {
  	int r;
  	struct zd_usb *usb;
  	struct zd_usb_rx *rx;
  	const u8 *buffer;
  	unsigned int length;
  	unsigned long flags;
  
  	switch (urb->status) {
  	case 0:
  		break;
  	case -ESHUTDOWN:
  	case -EINVAL:
  	case -ENODEV:
  	case -ENOENT:
  	case -ECONNRESET:
  	case -EPIPE:
  		dev_dbg_f(urb_dev(urb), "urb %p error %d\n", urb, urb->status);
  		return;
  	default:
  		dev_dbg_f(urb_dev(urb), "urb %p error %d\n", urb, urb->status);
  		goto resubmit;
  	}
  
  	buffer = urb->transfer_buffer;
  	length = urb->actual_length;
  	usb = urb->context;
  	rx = &usb->rx;
  
  	tasklet_schedule(&rx->reset_timer_tasklet);
  
  	if (length%rx->usb_packet_size > rx->usb_packet_size-4) {
  		/* If there is an old first fragment, we don't care. */
  		dev_dbg_f(urb_dev(urb), "*** first fragment ***\n");
  		ZD_ASSERT(length <= ARRAY_SIZE(rx->fragment));
  		spin_lock_irqsave(&rx->lock, flags);
  		memcpy(rx->fragment, buffer, length);
  		rx->fragment_length = length;
  		spin_unlock_irqrestore(&rx->lock, flags);
  		goto resubmit;
  	}
  
  	spin_lock_irqsave(&rx->lock, flags);
  	if (rx->fragment_length > 0) {
  		/* We are on a second fragment, we believe */
  		ZD_ASSERT(length + rx->fragment_length <=
  			  ARRAY_SIZE(rx->fragment));
  		dev_dbg_f(urb_dev(urb), "*** second fragment ***\n");
  		memcpy(rx->fragment+rx->fragment_length, buffer, length);
  		handle_rx_packet(usb, rx->fragment,
  			         rx->fragment_length + length);
  		rx->fragment_length = 0;
  		spin_unlock_irqrestore(&rx->lock, flags);
  	} else {
  		spin_unlock_irqrestore(&rx->lock, flags);
  		handle_rx_packet(usb, buffer, length);
  	}
  
  resubmit:
  	r = usb_submit_urb(urb, GFP_ATOMIC);
  	if (r)
  		dev_dbg_f(urb_dev(urb), "urb %p resubmit error %d\n", urb, r);
  }
  
  static struct urb *alloc_rx_urb(struct zd_usb *usb)
  {
  	struct usb_device *udev = zd_usb_to_usbdev(usb);
  	struct urb *urb;
  	void *buffer;
  
  	urb = usb_alloc_urb(0, GFP_KERNEL);
  	if (!urb)
  		return NULL;
  	buffer = usb_alloc_coherent(udev, USB_MAX_RX_SIZE, GFP_KERNEL,
  				    &urb->transfer_dma);
  	if (!buffer) {
  		usb_free_urb(urb);
  		return NULL;
  	}
  
  	usb_fill_bulk_urb(urb, udev, usb_rcvbulkpipe(udev, EP_DATA_IN),
  			  buffer, USB_MAX_RX_SIZE,
  			  rx_urb_complete, usb);
  	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
  
  	return urb;
  }
  
  static void free_rx_urb(struct urb *urb)
  {
  	if (!urb)
  		return;
  	usb_free_coherent(urb->dev, urb->transfer_buffer_length,
  			  urb->transfer_buffer, urb->transfer_dma);
  	usb_free_urb(urb);
  }
  
  static int __zd_usb_enable_rx(struct zd_usb *usb)
  {
  	int i, r;
  	struct zd_usb_rx *rx = &usb->rx;
  	struct urb **urbs;
  
  	dev_dbg_f(zd_usb_dev(usb), "\n");
  
  	r = -ENOMEM;
  	urbs = kcalloc(RX_URBS_COUNT, sizeof(struct urb *), GFP_KERNEL);
  	if (!urbs)
  		goto error;
  	for (i = 0; i < RX_URBS_COUNT; i++) {
  		urbs[i] = alloc_rx_urb(usb);
  		if (!urbs[i])
  			goto error;
  	}
  
  	ZD_ASSERT(!irqs_disabled());
  	spin_lock_irq(&rx->lock);
  	if (rx->urbs) {
  		spin_unlock_irq(&rx->lock);
  		r = 0;
  		goto error;
  	}
  	rx->urbs = urbs;
  	rx->urbs_count = RX_URBS_COUNT;
  	spin_unlock_irq(&rx->lock);
  
  	for (i = 0; i < RX_URBS_COUNT; i++) {
  		r = usb_submit_urb(urbs[i], GFP_KERNEL);
  		if (r)
  			goto error_submit;
  	}
  
  	return 0;
  error_submit:
  	for (i = 0; i < RX_URBS_COUNT; i++) {
  		usb_kill_urb(urbs[i]);
  	}
  	spin_lock_irq(&rx->lock);
  	rx->urbs = NULL;
  	rx->urbs_count = 0;
  	spin_unlock_irq(&rx->lock);
  error:
  	if (urbs) {
  		for (i = 0; i < RX_URBS_COUNT; i++)
  			free_rx_urb(urbs[i]);
  	}
  	return r;
  }
  
  int zd_usb_enable_rx(struct zd_usb *usb)
  {
  	int r;
  	struct zd_usb_rx *rx = &usb->rx;
  
  	mutex_lock(&rx->setup_mutex);
  	r = __zd_usb_enable_rx(usb);
  	mutex_unlock(&rx->setup_mutex);
  
  	zd_usb_reset_rx_idle_timer(usb);
  
  	return r;
  }
  
  static void __zd_usb_disable_rx(struct zd_usb *usb)
  {
  	int i;
  	unsigned long flags;
  	struct urb **urbs;
  	unsigned int count;
  	struct zd_usb_rx *rx = &usb->rx;
  
  	spin_lock_irqsave(&rx->lock, flags);
  	urbs = rx->urbs;
  	count = rx->urbs_count;
  	spin_unlock_irqrestore(&rx->lock, flags);
  	if (!urbs)
  		return;
  
  	for (i = 0; i < count; i++) {
  		usb_kill_urb(urbs[i]);
  		free_rx_urb(urbs[i]);
  	}
  	kfree(urbs);
  
  	spin_lock_irqsave(&rx->lock, flags);
  	rx->urbs = NULL;
  	rx->urbs_count = 0;
  	spin_unlock_irqrestore(&rx->lock, flags);
  }
  
  void zd_usb_disable_rx(struct zd_usb *usb)
  {
  	struct zd_usb_rx *rx = &usb->rx;
  
  	mutex_lock(&rx->setup_mutex);
  	__zd_usb_disable_rx(usb);
  	mutex_unlock(&rx->setup_mutex);
  
  	tasklet_kill(&rx->reset_timer_tasklet);
  	cancel_delayed_work_sync(&rx->idle_work);
  }
  
  static void zd_usb_reset_rx(struct zd_usb *usb)
  {
  	bool do_reset;
  	struct zd_usb_rx *rx = &usb->rx;
  	unsigned long flags;
  
  	mutex_lock(&rx->setup_mutex);
  
  	spin_lock_irqsave(&rx->lock, flags);
  	do_reset = rx->urbs != NULL;
  	spin_unlock_irqrestore(&rx->lock, flags);
  
  	if (do_reset) {
  		__zd_usb_disable_rx(usb);
  		__zd_usb_enable_rx(usb);
  	}
  
  	mutex_unlock(&rx->setup_mutex);
  
  	if (do_reset)
  		zd_usb_reset_rx_idle_timer(usb);
  }
  
  /**
   * zd_usb_disable_tx - disable transmission
   * @usb: the zd1211rw-private USB structure
   *
   * Frees all URBs in the free list and marks the transmission as disabled.
   */
  void zd_usb_disable_tx(struct zd_usb *usb)
  {
  	struct zd_usb_tx *tx = &usb->tx;
  	unsigned long flags;
  
  	atomic_set(&tx->enabled, 0);
  
  	/* kill all submitted tx-urbs */
  	usb_kill_anchored_urbs(&tx->submitted);
  
  	spin_lock_irqsave(&tx->lock, flags);
  	WARN_ON(!skb_queue_empty(&tx->submitted_skbs));
  	WARN_ON(tx->submitted_urbs != 0);
  	tx->submitted_urbs = 0;
  	spin_unlock_irqrestore(&tx->lock, flags);
  
  	/* The stopped state is ignored, relying on ieee80211_wake_queues()
  	 * in a potentionally following zd_usb_enable_tx().
  	 */
  }
  
  /**
   * zd_usb_enable_tx - enables transmission
   * @usb: a &struct zd_usb pointer
   *
   * This function enables transmission and prepares the &zd_usb_tx data
   * structure.
   */
  void zd_usb_enable_tx(struct zd_usb *usb)
  {
  	unsigned long flags;
  	struct zd_usb_tx *tx = &usb->tx;
  
  	spin_lock_irqsave(&tx->lock, flags);
  	atomic_set(&tx->enabled, 1);
  	tx->submitted_urbs = 0;
  	ieee80211_wake_queues(zd_usb_to_hw(usb));
  	tx->stopped = 0;
  	spin_unlock_irqrestore(&tx->lock, flags);
  }
  
  static void tx_dec_submitted_urbs(struct zd_usb *usb)
  {
  	struct zd_usb_tx *tx = &usb->tx;
  	unsigned long flags;
  
  	spin_lock_irqsave(&tx->lock, flags);
  	--tx->submitted_urbs;
  	if (tx->stopped && tx->submitted_urbs <= ZD_USB_TX_LOW) {
  		ieee80211_wake_queues(zd_usb_to_hw(usb));
  		tx->stopped = 0;
  	}
  	spin_unlock_irqrestore(&tx->lock, flags);
  }
  
  static void tx_inc_submitted_urbs(struct zd_usb *usb)
  {
  	struct zd_usb_tx *tx = &usb->tx;
  	unsigned long flags;
  
  	spin_lock_irqsave(&tx->lock, flags);
  	++tx->submitted_urbs;
  	if (!tx->stopped && tx->submitted_urbs > ZD_USB_TX_HIGH) {
  		ieee80211_stop_queues(zd_usb_to_hw(usb));
  		tx->stopped = 1;
  	}
  	spin_unlock_irqrestore(&tx->lock, flags);
  }
  
  /**
   * tx_urb_complete - completes the execution of an URB
   * @urb: a URB
   *
   * This function is called if the URB has been transferred to a device or an
   * error has happened.
   */
  static void tx_urb_complete(struct urb *urb)
  {
  	int r;
  	struct sk_buff *skb;
  	struct ieee80211_tx_info *info;
  	struct zd_usb *usb;
  	struct zd_usb_tx *tx;
  
  	skb = (struct sk_buff *)urb->context;
  	info = IEEE80211_SKB_CB(skb);
  	/*
  	 * grab 'usb' pointer before handing off the skb (since
  	 * it might be freed by zd_mac_tx_to_dev or mac80211)
  	 */
  	usb = &zd_hw_mac(info->rate_driver_data[0])->chip.usb;
  	tx = &usb->tx;
  
  	switch (urb->status) {
  	case 0:
  		break;
  	case -ESHUTDOWN:
  	case -EINVAL:
  	case -ENODEV:
  	case -ENOENT:
  	case -ECONNRESET:
  	case -EPIPE:
  		dev_dbg_f(urb_dev(urb), "urb %p error %d\n", urb, urb->status);
  		break;
  	default:
  		dev_dbg_f(urb_dev(urb), "urb %p error %d\n", urb, urb->status);
  		goto resubmit;
  	}
  free_urb:
  	skb_unlink(skb, &usb->tx.submitted_skbs);
  	zd_mac_tx_to_dev(skb, urb->status);
  	usb_free_urb(urb);
  	tx_dec_submitted_urbs(usb);
  	return;
  resubmit:
  	usb_anchor_urb(urb, &tx->submitted);
  	r = usb_submit_urb(urb, GFP_ATOMIC);
  	if (r) {
  		usb_unanchor_urb(urb);
  		dev_dbg_f(urb_dev(urb), "error resubmit urb %p %d\n", urb, r);
  		goto free_urb;
  	}
  }
  
  /**
   * zd_usb_tx: initiates transfer of a frame of the device
   *
   * @usb: the zd1211rw-private USB structure
   * @skb: a &struct sk_buff pointer
   *
   * This function tranmits a frame to the device. It doesn't wait for
   * completion. The frame must contain the control set and have all the
   * control set information available.
   *
   * The function returns 0 if the transfer has been successfully initiated.
   */
  int zd_usb_tx(struct zd_usb *usb, struct sk_buff *skb)
  {
  	int r;
  	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
  	struct usb_device *udev = zd_usb_to_usbdev(usb);
  	struct urb *urb;
  	struct zd_usb_tx *tx = &usb->tx;
  
  	if (!atomic_read(&tx->enabled)) {
  		r = -ENOENT;
  		goto out;
  	}
  
  	urb = usb_alloc_urb(0, GFP_ATOMIC);
  	if (!urb) {
  		r = -ENOMEM;
  		goto out;
  	}
  
  	usb_fill_bulk_urb(urb, udev, usb_sndbulkpipe(udev, EP_DATA_OUT),
  		          skb->data, skb->len, tx_urb_complete, skb);
  
  	info->rate_driver_data[1] = (void *)jiffies;
  	skb_queue_tail(&tx->submitted_skbs, skb);
  	usb_anchor_urb(urb, &tx->submitted);
  
  	r = usb_submit_urb(urb, GFP_ATOMIC);
  	if (r) {
  		dev_dbg_f(zd_usb_dev(usb), "error submit urb %p %d\n", urb, r);
  		usb_unanchor_urb(urb);
  		skb_unlink(skb, &tx->submitted_skbs);
  		goto error;
  	}
  	tx_inc_submitted_urbs(usb);
  	return 0;
  error:
  	usb_free_urb(urb);
  out:
  	return r;
  }
  
  static bool zd_tx_timeout(struct zd_usb *usb)
  {
  	struct zd_usb_tx *tx = &usb->tx;
  	struct sk_buff_head *q = &tx->submitted_skbs;
  	struct sk_buff *skb, *skbnext;
  	struct ieee80211_tx_info *info;
  	unsigned long flags, trans_start;
  	bool have_timedout = false;
  
  	spin_lock_irqsave(&q->lock, flags);
  	skb_queue_walk_safe(q, skb, skbnext) {
  		info = IEEE80211_SKB_CB(skb);
  		trans_start = (unsigned long)info->rate_driver_data[1];
  
  		if (time_is_before_jiffies(trans_start + ZD_TX_TIMEOUT)) {
  			have_timedout = true;
  			break;
  		}
  	}
  	spin_unlock_irqrestore(&q->lock, flags);
  
  	return have_timedout;
  }
  
  static void zd_tx_watchdog_handler(struct work_struct *work)
  {
  	struct zd_usb *usb =
  		container_of(work, struct zd_usb, tx.watchdog_work.work);
  	struct zd_usb_tx *tx = &usb->tx;
  
  	if (!atomic_read(&tx->enabled) || !tx->watchdog_enabled)
  		goto out;
  	if (!zd_tx_timeout(usb))
  		goto out;
  
  	/* TX halted, try reset */
  	dev_warn(zd_usb_dev(usb), "TX-stall detected, resetting device...");
  
  	usb_queue_reset_device(usb->intf);
  
  	/* reset will stop this worker, don't rearm */
  	return;
  out:
  	queue_delayed_work(zd_workqueue, &tx->watchdog_work,
  			   ZD_TX_WATCHDOG_INTERVAL);
  }
  
  void zd_tx_watchdog_enable(struct zd_usb *usb)
  {
  	struct zd_usb_tx *tx = &usb->tx;
  
  	if (!tx->watchdog_enabled) {
  		dev_dbg_f(zd_usb_dev(usb), "\n");
  		queue_delayed_work(zd_workqueue, &tx->watchdog_work,
  				   ZD_TX_WATCHDOG_INTERVAL);
  		tx->watchdog_enabled = 1;
  	}
  }
  
  void zd_tx_watchdog_disable(struct zd_usb *usb)
  {
  	struct zd_usb_tx *tx = &usb->tx;
  
  	if (tx->watchdog_enabled) {
  		dev_dbg_f(zd_usb_dev(usb), "\n");
  		tx->watchdog_enabled = 0;
  		cancel_delayed_work_sync(&tx->watchdog_work);
  	}
  }
  
  static void zd_rx_idle_timer_handler(struct work_struct *work)
  {
  	struct zd_usb *usb =
  		container_of(work, struct zd_usb, rx.idle_work.work);
  	struct zd_mac *mac = zd_usb_to_mac(usb);
  
  	if (!test_bit(ZD_DEVICE_RUNNING, &mac->flags))
  		return;
  
  	dev_dbg_f(zd_usb_dev(usb), "\n");
  
  	/* 30 seconds since last rx, reset rx */
  	zd_usb_reset_rx(usb);
  }
  
  static void zd_usb_reset_rx_idle_timer_tasklet(unsigned long param)
  {
  	struct zd_usb *usb = (struct zd_usb *)param;
  
  	zd_usb_reset_rx_idle_timer(usb);
  }
  
  void zd_usb_reset_rx_idle_timer(struct zd_usb *usb)
  {
  	struct zd_usb_rx *rx = &usb->rx;
  
  	mod_delayed_work(zd_workqueue, &rx->idle_work, ZD_RX_IDLE_INTERVAL);
  }
  
  static inline void init_usb_interrupt(struct zd_usb *usb)
  {
  	struct zd_usb_interrupt *intr = &usb->intr;
  
  	spin_lock_init(&intr->lock);
  	intr->interval = int_urb_interval(zd_usb_to_usbdev(usb));
  	init_completion(&intr->read_regs.completion);
  	atomic_set(&intr->read_regs_enabled, 0);
  	intr->read_regs.cr_int_addr = cpu_to_le16((u16)CR_INTERRUPT);
  }
  
  static inline void init_usb_rx(struct zd_usb *usb)
  {
  	struct zd_usb_rx *rx = &usb->rx;
  
  	spin_lock_init(&rx->lock);
  	mutex_init(&rx->setup_mutex);
  	if (interface_to_usbdev(usb->intf)->speed == USB_SPEED_HIGH) {
  		rx->usb_packet_size = 512;
  	} else {
  		rx->usb_packet_size = 64;
  	}
  	ZD_ASSERT(rx->fragment_length == 0);
  	INIT_DELAYED_WORK(&rx->idle_work, zd_rx_idle_timer_handler);
  	rx->reset_timer_tasklet.func = zd_usb_reset_rx_idle_timer_tasklet;
  	rx->reset_timer_tasklet.data = (unsigned long)usb;
  }
  
  static inline void init_usb_tx(struct zd_usb *usb)
  {
  	struct zd_usb_tx *tx = &usb->tx;
  
  	spin_lock_init(&tx->lock);
  	atomic_set(&tx->enabled, 0);
  	tx->stopped = 0;
  	skb_queue_head_init(&tx->submitted_skbs);
  	init_usb_anchor(&tx->submitted);
  	tx->submitted_urbs = 0;
  	tx->watchdog_enabled = 0;
  	INIT_DELAYED_WORK(&tx->watchdog_work, zd_tx_watchdog_handler);
  }
  
  void zd_usb_init(struct zd_usb *usb, struct ieee80211_hw *hw,
  	         struct usb_interface *intf)
  {
  	memset(usb, 0, sizeof(*usb));
  	usb->intf = usb_get_intf(intf);
  	usb_set_intfdata(usb->intf, hw);
  	init_usb_anchor(&usb->submitted_cmds);
  	init_usb_interrupt(usb);
  	init_usb_tx(usb);
  	init_usb_rx(usb);
  }
  
  void zd_usb_clear(struct zd_usb *usb)
  {
  	usb_set_intfdata(usb->intf, NULL);
  	usb_put_intf(usb->intf);
  	ZD_MEMCLEAR(usb, sizeof(*usb));
  	/* FIXME: usb_interrupt, usb_tx, usb_rx? */
  }
  
  static const char *speed(enum usb_device_speed speed)
  {
  	switch (speed) {
  	case USB_SPEED_LOW:
  		return "low";
  	case USB_SPEED_FULL:
  		return "full";
  	case USB_SPEED_HIGH:
  		return "high";
  	default:
  		return "unknown speed";
  	}
  }
  
  static int scnprint_id(struct usb_device *udev, char *buffer, size_t size)
  {
  	return scnprintf(buffer, size, "%04hx:%04hx v%04hx %s",
  		le16_to_cpu(udev->descriptor.idVendor),
  		le16_to_cpu(udev->descriptor.idProduct),
  		get_bcdDevice(udev),
  		speed(udev->speed));
  }
  
  int zd_usb_scnprint_id(struct zd_usb *usb, char *buffer, size_t size)
  {
  	struct usb_device *udev = interface_to_usbdev(usb->intf);
  	return scnprint_id(udev, buffer, size);
  }
  
  #ifdef DEBUG
  static void print_id(struct usb_device *udev)
  {
  	char buffer[40];
  
  	scnprint_id(udev, buffer, sizeof(buffer));
  	buffer[sizeof(buffer)-1] = 0;
  	dev_dbg_f(&udev->dev, "%s\n", buffer);
  }
  #else
  #define print_id(udev) do { } while (0)
  #endif
  
  static int eject_installer(struct usb_interface *intf)
  {
  	struct usb_device *udev = interface_to_usbdev(intf);
  	struct usb_host_interface *iface_desc = intf->cur_altsetting;
  	struct usb_endpoint_descriptor *endpoint;
  	unsigned char *cmd;
  	u8 bulk_out_ep;
  	int r;
  
  	if (iface_desc->desc.bNumEndpoints < 2)
  		return -ENODEV;
  
  	/* Find bulk out endpoint */
  	for (r = 1; r >= 0; r--) {
  		endpoint = &iface_desc->endpoint[r].desc;
  		if (usb_endpoint_dir_out(endpoint) &&
  		    usb_endpoint_xfer_bulk(endpoint)) {
  			bulk_out_ep = endpoint->bEndpointAddress;
  			break;
  		}
  	}
  	if (r == -1) {
  		dev_err(&udev->dev,
  			"zd1211rw: Could not find bulk out endpoint\n");
  		return -ENODEV;
  	}
  
  	cmd = kzalloc(31, GFP_KERNEL);
  	if (cmd == NULL)
  		return -ENODEV;
  
  	/* USB bulk command block */
  	cmd[0] = 0x55;	/* bulk command signature */
  	cmd[1] = 0x53;	/* bulk command signature */
  	cmd[2] = 0x42;	/* bulk command signature */
  	cmd[3] = 0x43;	/* bulk command signature */
  	cmd[14] = 6;	/* command length */
  
  	cmd[15] = 0x1b;	/* SCSI command: START STOP UNIT */
  	cmd[19] = 0x2;	/* eject disc */
  
  	dev_info(&udev->dev, "Ejecting virtual installer media...\n");
  	r = usb_bulk_msg(udev, usb_sndbulkpipe(udev, bulk_out_ep),
  		cmd, 31, NULL, 2000);
  	kfree(cmd);
  	if (r)
  		return r;
  
  	/* At this point, the device disconnects and reconnects with the real
  	 * ID numbers. */
  
  	usb_set_intfdata(intf, NULL);
  	return 0;
  }
  
  int zd_usb_init_hw(struct zd_usb *usb)
  {
  	int r;
  	struct zd_mac *mac = zd_usb_to_mac(usb);
  
  	dev_dbg_f(zd_usb_dev(usb), "\n");
  
  	r = upload_firmware(usb);
  	if (r) {
  		dev_err(zd_usb_dev(usb),
  		       "couldn't load firmware. Error number %d\n", r);
  		return r;
  	}
  
  	r = usb_reset_configuration(zd_usb_to_usbdev(usb));
  	if (r) {
  		dev_dbg_f(zd_usb_dev(usb),
  			"couldn't reset configuration. Error number %d\n", r);
  		return r;
  	}
  
  	r = zd_mac_init_hw(mac->hw);
  	if (r) {
  		dev_dbg_f(zd_usb_dev(usb),
  		         "couldn't initialize mac. Error number %d\n", r);
  		return r;
  	}
  
  	usb->initialized = 1;
  	return 0;
  }
  
  static int probe(struct usb_interface *intf, const struct usb_device_id *id)
  {
  	int r;
  	struct usb_device *udev = interface_to_usbdev(intf);
  	struct zd_usb *usb;
  	struct ieee80211_hw *hw = NULL;
  
  	print_id(udev);
  
  	if (id->driver_info & DEVICE_INSTALLER)
  		return eject_installer(intf);
  
  	switch (udev->speed) {
  	case USB_SPEED_LOW:
  	case USB_SPEED_FULL:
  	case USB_SPEED_HIGH:
  		break;
  	default:
  		dev_dbg_f(&intf->dev, "Unknown USB speed\n");
  		r = -ENODEV;
  		goto error;
  	}
  
  	r = usb_reset_device(udev);
  	if (r) {
  		dev_err(&intf->dev,
  			"couldn't reset usb device. Error number %d\n", r);
  		goto error;
  	}
  
  	hw = zd_mac_alloc_hw(intf);
  	if (hw == NULL) {
  		r = -ENOMEM;
  		goto error;
  	}
  
  	usb = &zd_hw_mac(hw)->chip.usb;
  	usb->is_zd1211b = (id->driver_info == DEVICE_ZD1211B) != 0;
  
  	r = zd_mac_preinit_hw(hw);
  	if (r) {
  		dev_dbg_f(&intf->dev,
  		         "couldn't initialize mac. Error number %d\n", r);
  		goto error;
  	}
  
  	r = ieee80211_register_hw(hw);
  	if (r) {
  		dev_dbg_f(&intf->dev,
  			 "couldn't register device. Error number %d\n", r);
  		goto error;
  	}
  
  	dev_dbg_f(&intf->dev, "successful\n");
  	dev_info(&intf->dev, "%s\n", wiphy_name(hw->wiphy));
  	return 0;
  error:
  	usb_reset_device(interface_to_usbdev(intf));
  	if (hw) {
  		zd_mac_clear(zd_hw_mac(hw));
  		ieee80211_free_hw(hw);
  	}
  	return r;
  }
  
  static void disconnect(struct usb_interface *intf)
  {
  	struct ieee80211_hw *hw = zd_intf_to_hw(intf);
  	struct zd_mac *mac;
  	struct zd_usb *usb;
  
  	/* Either something really bad happened, or we're just dealing with
  	 * a DEVICE_INSTALLER. */
  	if (hw == NULL)
  		return;
  
  	mac = zd_hw_mac(hw);
  	usb = &mac->chip.usb;
  
  	dev_dbg_f(zd_usb_dev(usb), "\n");
  
  	ieee80211_unregister_hw(hw);
  
  	/* Just in case something has gone wrong! */
  	zd_usb_disable_tx(usb);
  	zd_usb_disable_rx(usb);
  	zd_usb_disable_int(usb);
  
  	/* If the disconnect has been caused by a removal of the
  	 * driver module, the reset allows reloading of the driver. If the
  	 * reset will not be executed here, the upload of the firmware in the
  	 * probe function caused by the reloading of the driver will fail.
  	 */
  	usb_reset_device(interface_to_usbdev(intf));
  
  	zd_mac_clear(mac);
  	ieee80211_free_hw(hw);
  	dev_dbg(&intf->dev, "disconnected\n");
  }
  
  static void zd_usb_resume(struct zd_usb *usb)
  {
  	struct zd_mac *mac = zd_usb_to_mac(usb);
  	int r;
  
  	dev_dbg_f(zd_usb_dev(usb), "\n");
  
  	r = zd_op_start(zd_usb_to_hw(usb));
  	if (r < 0) {
  		dev_warn(zd_usb_dev(usb), "Device resume failed "
  			 "with error code %d. Retrying...\n", r);
  		if (usb->was_running)
  			set_bit(ZD_DEVICE_RUNNING, &mac->flags);
  		usb_queue_reset_device(usb->intf);
  		return;
  	}
  
  	if (mac->type != NL80211_IFTYPE_UNSPECIFIED) {
  		r = zd_restore_settings(mac);
  		if (r < 0) {
  			dev_dbg(zd_usb_dev(usb),
  				"failed to restore settings, %d\n", r);
  			return;
  		}
  	}
  }
  
  static void zd_usb_stop(struct zd_usb *usb)
  {
  	dev_dbg_f(zd_usb_dev(usb), "\n");
  
  	zd_op_stop(zd_usb_to_hw(usb));
  
  	zd_usb_disable_tx(usb);
  	zd_usb_disable_rx(usb);
  	zd_usb_disable_int(usb);
  
  	usb->initialized = 0;
  }
  
  static int pre_reset(struct usb_interface *intf)
  {
  	struct ieee80211_hw *hw = usb_get_intfdata(intf);
  	struct zd_mac *mac;
  	struct zd_usb *usb;
  
  	if (!hw || intf->condition != USB_INTERFACE_BOUND)
  		return 0;
  
  	mac = zd_hw_mac(hw);
  	usb = &mac->chip.usb;
  
  	usb->was_running = test_bit(ZD_DEVICE_RUNNING, &mac->flags);
  
  	zd_usb_stop(usb);
  
  	mutex_lock(&mac->chip.mutex);
  	return 0;
  }
  
  static int post_reset(struct usb_interface *intf)
  {
  	struct ieee80211_hw *hw = usb_get_intfdata(intf);
  	struct zd_mac *mac;
  	struct zd_usb *usb;
  
  	if (!hw || intf->condition != USB_INTERFACE_BOUND)
  		return 0;
  
  	mac = zd_hw_mac(hw);
  	usb = &mac->chip.usb;
  
  	mutex_unlock(&mac->chip.mutex);
  
  	if (usb->was_running)
  		zd_usb_resume(usb);
  	return 0;
  }
  
  static struct usb_driver driver = {
  	.name		= KBUILD_MODNAME,
  	.id_table	= usb_ids,
  	.probe		= probe,
  	.disconnect	= disconnect,
  	.pre_reset	= pre_reset,
  	.post_reset	= post_reset,
  #if LINUX_VERSION_IS_GEQ(3,5,0)
  	.disable_hub_initiated_lpm = 1,
  #endif
  };
  
  struct workqueue_struct *zd_workqueue;
  
  static int __init usb_init(void)
  {
  	int r;
  
  	pr_debug("%s usb_init()\n", driver.name);
  
  	zd_workqueue = create_singlethread_workqueue(driver.name);
  	if (zd_workqueue == NULL) {
  		printk(KERN_ERR "%s couldn't create workqueue\n", driver.name);
  		return -ENOMEM;
  	}
  
  	r = usb_register(&driver);
  	if (r) {
  		destroy_workqueue(zd_workqueue);
  		printk(KERN_ERR "%s usb_register() failed. Error number %d\n",
  		       driver.name, r);
  		return r;
  	}
  
  	pr_debug("%s initialized\n", driver.name);
  	return 0;
  }
  
  static void __exit usb_exit(void)
  {
  	pr_debug("%s usb_exit()\n", driver.name);
  	usb_deregister(&driver);
  	destroy_workqueue(zd_workqueue);
  }
  
  module_init(usb_init);
  module_exit(usb_exit);
  
  static int zd_ep_regs_out_msg(struct usb_device *udev, void *data, int len,
  			      int *actual_length, int timeout)
  {
  	/* In USB 2.0 mode EP_REGS_OUT endpoint is interrupt type. However in
  	 * USB 1.1 mode endpoint is bulk. Select correct type URB by endpoint
  	 * descriptor.
  	 */
  	struct usb_host_endpoint *ep;
  	unsigned int pipe;
  
  	pipe = usb_sndintpipe(udev, EP_REGS_OUT);
  	ep = usb_pipe_endpoint(udev, pipe);
  	if (!ep)
  		return -EINVAL;
  
  	if (usb_endpoint_xfer_int(&ep->desc)) {
  		return usb_interrupt_msg(udev, pipe, data, len,
  					 actual_length, timeout);
  	} else {
  		pipe = usb_sndbulkpipe(udev, EP_REGS_OUT);
  		return usb_bulk_msg(udev, pipe, data, len, actual_length,
  				    timeout);
  	}
  }
  
  static void prepare_read_regs_int(struct zd_usb *usb,
  				  struct usb_req_read_regs *req,
  				  unsigned int count)
  {
  	struct zd_usb_interrupt *intr = &usb->intr;
  
  	spin_lock_irq(&intr->lock);
  	atomic_set(&intr->read_regs_enabled, 1);
  	intr->read_regs.req = req;
  	intr->read_regs.req_count = count;
  	reinit_completion(&intr->read_regs.completion);
  	spin_unlock_irq(&intr->lock);
  }
  
  static void disable_read_regs_int(struct zd_usb *usb)
  {
  	struct zd_usb_interrupt *intr = &usb->intr;
  
  	spin_lock_irq(&intr->lock);
  	atomic_set(&intr->read_regs_enabled, 0);
  	spin_unlock_irq(&intr->lock);
  }
  
  static bool check_read_regs(struct zd_usb *usb, struct usb_req_read_regs *req,
  			    unsigned int count)
  {
  	int i;
  	struct zd_usb_interrupt *intr = &usb->intr;
  	struct read_regs_int *rr = &intr->read_regs;
  	struct usb_int_regs *regs = (struct usb_int_regs *)rr->buffer;
  
  	/* The created block size seems to be larger than expected.
  	 * However results appear to be correct.
  	 */
  	if (rr->length < struct_size(regs, regs, count)) {
  		dev_dbg_f(zd_usb_dev(usb),
  			 "error: actual length %d less than expected %zu\n",
  			 rr->length, struct_size(regs, regs, count));
  		return false;
  	}
  
  	if (rr->length > sizeof(rr->buffer)) {
  		dev_dbg_f(zd_usb_dev(usb),
  			 "error: actual length %d exceeds buffer size %zu\n",
  			 rr->length, sizeof(rr->buffer));
  		return false;
  	}
  
  	for (i = 0; i < count; i++) {
  		struct reg_data *rd = &regs->regs[i];
  		if (rd->addr != req->addr[i]) {
  			dev_dbg_f(zd_usb_dev(usb),
  				 "rd[%d] addr %#06hx expected %#06hx\n", i,
  				 le16_to_cpu(rd->addr),
  				 le16_to_cpu(req->addr[i]));
  			return false;
  		}
  	}
  
  	return true;
  }
  
  static int get_results(struct zd_usb *usb, u16 *values,
  		       struct usb_req_read_regs *req, unsigned int count,
  		       bool *retry)
  {
  	int r;
  	int i;
  	struct zd_usb_interrupt *intr = &usb->intr;
  	struct read_regs_int *rr = &intr->read_regs;
  	struct usb_int_regs *regs = (struct usb_int_regs *)rr->buffer;
  
  	spin_lock_irq(&intr->lock);
  
  	r = -EIO;
  
  	/* Read failed because firmware bug? */
  	*retry = !!intr->read_regs_int_overridden;
  	if (*retry)
  		goto error_unlock;
  
  	if (!check_read_regs(usb, req, count)) {
  		dev_dbg_f(zd_usb_dev(usb), "error: invalid read regs\n");
  		goto error_unlock;
  	}
  
  	for (i = 0; i < count; i++) {
  		struct reg_data *rd = &regs->regs[i];
  		values[i] = le16_to_cpu(rd->value);
  	}
  
  	r = 0;
  error_unlock:
  	spin_unlock_irq(&intr->lock);
  	return r;
  }
  
  int zd_usb_ioread16v(struct zd_usb *usb, u16 *values,
  	             const zd_addr_t *addresses, unsigned int count)
  {
  	int r, i, req_len, actual_req_len, try_count = 0;
  	struct usb_device *udev;
  	struct usb_req_read_regs *req = NULL;
  	unsigned long timeout;
  	bool retry = false;
  
  	if (count < 1) {
  		dev_dbg_f(zd_usb_dev(usb), "error: count is zero\n");
  		return -EINVAL;
  	}
  	if (count > USB_MAX_IOREAD16_COUNT) {
  		dev_dbg_f(zd_usb_dev(usb),
  			 "error: count %u exceeds possible max %u\n",
  			 count, USB_MAX_IOREAD16_COUNT);
  		return -EINVAL;
  	}
  	if (in_atomic()) {
  		dev_dbg_f(zd_usb_dev(usb),
  			 "error: io in atomic context not supported\n");
  		return -EWOULDBLOCK;
  	}
  	if (!usb_int_enabled(usb)) {
  		dev_dbg_f(zd_usb_dev(usb),
  			  "error: usb interrupt not enabled\n");
  		return -EWOULDBLOCK;
  	}
  
  	ZD_ASSERT(mutex_is_locked(&zd_usb_to_chip(usb)->mutex));
  	BUILD_BUG_ON(sizeof(struct usb_req_read_regs) + USB_MAX_IOREAD16_COUNT *
  		     sizeof(__le16) > sizeof(usb->req_buf));
  	BUG_ON(sizeof(struct usb_req_read_regs) + count * sizeof(__le16) >
  	       sizeof(usb->req_buf));
  
  	req_len = sizeof(struct usb_req_read_regs) + count * sizeof(__le16);
  	req = (void *)usb->req_buf;
  
  	req->id = cpu_to_le16(USB_REQ_READ_REGS);
  	for (i = 0; i < count; i++)
  		req->addr[i] = cpu_to_le16((u16)addresses[i]);
  
  retry_read:
  	try_count++;
  	udev = zd_usb_to_usbdev(usb);
  	prepare_read_regs_int(usb, req, count);
  	r = zd_ep_regs_out_msg(udev, req, req_len, &actual_req_len, 50 /*ms*/);
  	if (r) {
  		dev_dbg_f(zd_usb_dev(usb),
  			"error in zd_ep_regs_out_msg(). Error number %d\n", r);
  		goto error;
  	}
  	if (req_len != actual_req_len) {
  		dev_dbg_f(zd_usb_dev(usb), "error in zd_ep_regs_out_msg()\n"
  			" req_len %d != actual_req_len %d\n",
  			req_len, actual_req_len);
  		r = -EIO;
  		goto error;
  	}
  
  	timeout = wait_for_completion_timeout(&usb->intr.read_regs.completion,
  					      msecs_to_jiffies(50));
  	if (!timeout) {
  		disable_read_regs_int(usb);
  		dev_dbg_f(zd_usb_dev(usb), "read timed out\n");
  		r = -ETIMEDOUT;
  		goto error;
  	}
  
  	r = get_results(usb, values, req, count, &retry);
  	if (retry && try_count < 20) {
  		dev_dbg_f(zd_usb_dev(usb), "read retry, tries so far: %d\n",
  				try_count);
  		goto retry_read;
  	}
  error:
  	return r;
  }
  
  static void iowrite16v_urb_complete(struct urb *urb)
  {
  	struct zd_usb *usb = urb->context;
  
  	if (urb->status && !usb->cmd_error)
  		usb->cmd_error = urb->status;
  
  	if (!usb->cmd_error &&
  			urb->actual_length != urb->transfer_buffer_length)
  		usb->cmd_error = -EIO;
  }
  
  static int zd_submit_waiting_urb(struct zd_usb *usb, bool last)
  {
  	int r = 0;
  	struct urb *urb = usb->urb_async_waiting;
  
  	if (!urb)
  		return 0;
  
  	usb->urb_async_waiting = NULL;
  
  	if (!last)
  		urb->transfer_flags |= URB_NO_INTERRUPT;
  
  	usb_anchor_urb(urb, &usb->submitted_cmds);
  	r = usb_submit_urb(urb, GFP_KERNEL);
  	if (r) {
  		usb_unanchor_urb(urb);
  		dev_dbg_f(zd_usb_dev(usb),
  			"error in usb_submit_urb(). Error number %d\n", r);
  		goto error;
  	}
  
  	/* fall-through with r == 0 */
  error:
  	usb_free_urb(urb);
  	return r;
  }
  
  void zd_usb_iowrite16v_async_start(struct zd_usb *usb)
  {
  	ZD_ASSERT(usb_anchor_empty(&usb->submitted_cmds));
  	ZD_ASSERT(usb->urb_async_waiting == NULL);
  	ZD_ASSERT(!usb->in_async);
  
  	ZD_ASSERT(mutex_is_locked(&zd_usb_to_chip(usb)->mutex));
  
  	usb->in_async = 1;
  	usb->cmd_error = 0;
  	usb->urb_async_waiting = NULL;
  }
  
  int zd_usb_iowrite16v_async_end(struct zd_usb *usb, unsigned int timeout)
  {
  	int r;
  
  	ZD_ASSERT(mutex_is_locked(&zd_usb_to_chip(usb)->mutex));
  	ZD_ASSERT(usb->in_async);
  
  	/* Submit last iowrite16v URB */
  	r = zd_submit_waiting_urb(usb, true);
  	if (r) {
  		dev_dbg_f(zd_usb_dev(usb),
  			"error in zd_submit_waiting_usb(). "
  			"Error number %d\n", r);
  
  		usb_kill_anchored_urbs(&usb->submitted_cmds);
  		goto error;
  	}
  
  	if (timeout)
  		timeout = usb_wait_anchor_empty_timeout(&usb->submitted_cmds,
  							timeout);
  	if (!timeout) {
  		usb_kill_anchored_urbs(&usb->submitted_cmds);
  		if (usb->cmd_error == -ENOENT) {
  			dev_dbg_f(zd_usb_dev(usb), "timed out");
  			r = -ETIMEDOUT;
  			goto error;
  		}
  	}
  
  	r = usb->cmd_error;
  error:
  	usb->in_async = 0;
  	return r;
  }
  
  int zd_usb_iowrite16v_async(struct zd_usb *usb, const struct zd_ioreq16 *ioreqs,
  			    unsigned int count)
  {
  	int r;
  	struct usb_device *udev;
  	struct usb_req_write_regs *req = NULL;
  	int i, req_len;
  	struct urb *urb;
  	struct usb_host_endpoint *ep;
  
  	ZD_ASSERT(mutex_is_locked(&zd_usb_to_chip(usb)->mutex));
  	ZD_ASSERT(usb->in_async);
  
  	if (count == 0)
  		return 0;
  	if (count > USB_MAX_IOWRITE16_COUNT) {
  		dev_dbg_f(zd_usb_dev(usb),
  			"error: count %u exceeds possible max %u\n",
  			count, USB_MAX_IOWRITE16_COUNT);
  		return -EINVAL;
  	}
  	if (in_atomic()) {
  		dev_dbg_f(zd_usb_dev(usb),
  			"error: io in atomic context not supported\n");
  		return -EWOULDBLOCK;
  	}
  
  	udev = zd_usb_to_usbdev(usb);
  
  	ep = usb_pipe_endpoint(udev, usb_sndintpipe(udev, EP_REGS_OUT));
  	if (!ep)
  		return -ENOENT;
  
  	urb = usb_alloc_urb(0, GFP_KERNEL);
  	if (!urb)
  		return -ENOMEM;
  
  	req_len = struct_size(req, reg_writes, count);
  	req = kmalloc(req_len, GFP_KERNEL);
  	if (!req) {
  		r = -ENOMEM;
  		goto error;
  	}
  
  	req->id = cpu_to_le16(USB_REQ_WRITE_REGS);
  	for (i = 0; i < count; i++) {
  		struct reg_data *rw  = &req->reg_writes[i];
  		rw->addr = cpu_to_le16((u16)ioreqs[i].addr);
  		rw->value = cpu_to_le16(ioreqs[i].value);
  	}
  
  	/* In USB 2.0 mode endpoint is interrupt type. However in USB 1.1 mode
  	 * endpoint is bulk. Select correct type URB by endpoint descriptor.
  	 */
  	if (usb_endpoint_xfer_int(&ep->desc))
  		usb_fill_int_urb(urb, udev, usb_sndintpipe(udev, EP_REGS_OUT),
  				 req, req_len, iowrite16v_urb_complete, usb,
  				 ep->desc.bInterval);
  	else
  		usb_fill_bulk_urb(urb, udev, usb_sndbulkpipe(udev, EP_REGS_OUT),
  				  req, req_len, iowrite16v_urb_complete, usb);
  
  	urb->transfer_flags |= URB_FREE_BUFFER;
  
  	/* Submit previous URB */
  	r = zd_submit_waiting_urb(usb, false);
  	if (r) {
  		dev_dbg_f(zd_usb_dev(usb),
  			"error in zd_submit_waiting_usb(). "
  			"Error number %d\n", r);
  		goto error;
  	}
  
  	/* Delay submit so that URB_NO_INTERRUPT flag can be set for all URBs
  	 * of currect batch except for very last.
  	 */
  	usb->urb_async_waiting = urb;
  	return 0;
  error:
  	usb_free_urb(urb);
  	return r;
  }
  
  int zd_usb_iowrite16v(struct zd_usb *usb, const struct zd_ioreq16 *ioreqs,
  			unsigned int count)
  {
  	int r;
  
  	zd_usb_iowrite16v_async_start(usb);
  	r = zd_usb_iowrite16v_async(usb, ioreqs, count);
  	if (r) {
  		zd_usb_iowrite16v_async_end(usb, 0);
  		return r;
  	}
  	return zd_usb_iowrite16v_async_end(usb, 50 /* ms */);
  }
  
  int zd_usb_rfwrite(struct zd_usb *usb, u32 value, u8 bits)
  {
  	int r;
  	struct usb_device *udev;
  	struct usb_req_rfwrite *req = NULL;
  	int i, req_len, actual_req_len;
  	u16 bit_value_template;
  
  	if (in_atomic()) {
  		dev_dbg_f(zd_usb_dev(usb),
  			"error: io in atomic context not supported\n");
  		return -EWOULDBLOCK;
  	}
  	if (bits < USB_MIN_RFWRITE_BIT_COUNT) {
  		dev_dbg_f(zd_usb_dev(usb),
  			"error: bits %d are smaller than"
  			" USB_MIN_RFWRITE_BIT_COUNT %d\n",
  			bits, USB_MIN_RFWRITE_BIT_COUNT);
  		return -EINVAL;
  	}
  	if (bits > USB_MAX_RFWRITE_BIT_COUNT) {
  		dev_dbg_f(zd_usb_dev(usb),
  			"error: bits %d exceed USB_MAX_RFWRITE_BIT_COUNT %d\n",
  			bits, USB_MAX_RFWRITE_BIT_COUNT);
  		return -EINVAL;
  	}
  #ifdef DEBUG
  	if (value & (~0UL << bits)) {
  		dev_dbg_f(zd_usb_dev(usb),
  			"error: value %#09x has bits >= %d set\n",
  			value, bits);
  		return -EINVAL;
  	}
  #endif /* DEBUG */
  
  	dev_dbg_f(zd_usb_dev(usb), "value %#09x bits %d\n", value, bits);
  
  	r = zd_usb_ioread16(usb, &bit_value_template, ZD_CR203);
  	if (r) {
  		dev_dbg_f(zd_usb_dev(usb),
  			"error %d: Couldn't read ZD_CR203\n", r);
  		return r;
  	}
  	bit_value_template &= ~(RF_IF_LE|RF_CLK|RF_DATA);
  
  	ZD_ASSERT(mutex_is_locked(&zd_usb_to_chip(usb)->mutex));
  	BUILD_BUG_ON(sizeof(struct usb_req_rfwrite) +
  		     USB_MAX_RFWRITE_BIT_COUNT * sizeof(__le16) >
  		     sizeof(usb->req_buf));
  	BUG_ON(sizeof(struct usb_req_rfwrite) + bits * sizeof(__le16) >
  	       sizeof(usb->req_buf));
  
  	req_len = sizeof(struct usb_req_rfwrite) + bits * sizeof(__le16);
  	req = (void *)usb->req_buf;
  
  	req->id = cpu_to_le16(USB_REQ_WRITE_RF);
  	/* 1: 3683a, but not used in ZYDAS driver */
  	req->value = cpu_to_le16(2);
  	req->bits = cpu_to_le16(bits);
  
  	for (i = 0; i < bits; i++) {
  		u16 bv = bit_value_template;
  		if (value & (1 << (bits-1-i)))
  			bv |= RF_DATA;
  		req->bit_values[i] = cpu_to_le16(bv);
  	}
  
  	udev = zd_usb_to_usbdev(usb);
  	r = zd_ep_regs_out_msg(udev, req, req_len, &actual_req_len, 50 /*ms*/);
  	if (r) {
  		dev_dbg_f(zd_usb_dev(usb),
  			"error in zd_ep_regs_out_msg(). Error number %d\n", r);
  		goto out;
  	}
  	if (req_len != actual_req_len) {
  		dev_dbg_f(zd_usb_dev(usb), "error in zd_ep_regs_out_msg()"
  			" req_len %d != actual_req_len %d\n",
  			req_len, actual_req_len);
  		r = -EIO;
  		goto out;
  	}
  
  	/* FALL-THROUGH with r == 0 */
  out:
  	return r;
  }
  