usb.c

/*
 * Most of this source has been derived from the Linux USB
 * project:
 * (C) Copyright Linus Torvalds 1999
 * (C) Copyright Johannes Erdfelt 1999-2001
 * (C) Copyright Andreas Gal 1999
 * (C) Copyright Gregory P. Smith 1999
 * (C) Copyright Deti Fliegl 1999 (new USB architecture)
 * (C) Copyright Randy Dunlap 2000
 * (C) Copyright David Brownell 2000 (kernel hotplug, usb_device_id)
 * (C) Copyright Yggdrasil Computing, Inc. 2000
 *     (usb_device_id matching changes by Adam J. Richter)
 *
 * Adapted for U-Boot:
 * (C) Copyright 2001 Denis Peter, MPL AG Switzerland
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

/*
 * How it works:
 *
 * Since this is a bootloader, the devices will not be automatic
 * (re)configured on hotplug, but after a restart of the USB the
 * device should work.
 *
 * For each transfer (except "Interrupt") we wait for completion.
 */
#include <common.h>
#include <command.h>
#include <dm.h>
#include <asm/processor.h>
#include <linux/compiler.h>
#include <linux/ctype.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>
#include <errno.h>
#include <usb.h>
#ifdef CONFIG_4xx
#include <asm/4xx_pci.h>
#endif

#define USB_BUFSIZ	512

static int asynch_allowed;
char usb_started; /* flag for the started/stopped USB status */

#ifndef CONFIG_DM_USB
static struct usb_device usb_dev[USB_MAX_DEVICE];
static int dev_index;

#ifndef CONFIG_USB_MAX_CONTROLLER_COUNT
#define CONFIG_USB_MAX_CONTROLLER_COUNT 1
#endif

/***************************************************************************
 * Init USB Device
 */
int usb_init(void)
{
	void *ctrl;
	struct usb_device *dev;
	int i, start_index = 0;
	int controllers_initialized = 0;
	int ret;

	dev_index = 0;
	asynch_allowed = 1;
	usb_hub_reset();

	/* first make all devices unknown */
	for (i = 0; i < USB_MAX_DEVICE; i++) {
		memset(&usb_dev[i], 0, sizeof(struct usb_device));
		usb_dev[i].devnum = -1;
	}

	/* init low_level USB */
	for (i = 0; i < CONFIG_USB_MAX_CONTROLLER_COUNT; i++) {
		/* init low_level USB */
		printf("USB%d:   ", i);
		ret = usb_lowlevel_init(i, USB_INIT_HOST, &ctrl);
		if (ret == -ENODEV) {	/* No such device. */
			puts("Port not available.\n");
			controllers_initialized++;
			continue;
		}

		if (ret) {		/* Other error. */
			puts("lowlevel init failed\n");
			continue;
		}
		/*
		 * lowlevel init is OK, now scan the bus for devices
		 * i.e. search HUBs and configure them
		 */
		controllers_initialized++;
		start_index = dev_index;
		printf("scanning bus %d for devices... ", i);
		ret = usb_alloc_new_device(ctrl, &dev);
		if (ret)
			break;

		/*
		 * device 0 is always present
		 * (root hub, so let it analyze)
		 */
		ret = usb_new_device(dev);
		if (ret)
			usb_free_device(dev->controller);

		if (start_index == dev_index) {
			puts("No USB Device found\n");
			continue;
		} else {
			printf("%d USB Device(s) found\n",
				dev_index - start_index);
		}

		usb_started = 1;
	}

	debug("scan end\n");
	/* if we were not able to find at least one working bus, bail out */
	if (controllers_initialized == 0)
		puts("USB error: all controllers failed lowlevel init\n");

	return usb_started ? 0 : -ENODEV;
}

/******************************************************************************
 * Stop USB this stops the LowLevel Part and deregisters USB devices.
 */
int usb_stop(void)
{
	int i;

	if (usb_started) {
		asynch_allowed = 1;
		usb_started = 0;
		usb_hub_reset();

		for (i = 0; i < CONFIG_USB_MAX_CONTROLLER_COUNT; i++) {
			if (usb_lowlevel_stop(i))
				printf("failed to stop USB controller %d\n", i);
		}
	}

	return 0;
}

/*
 * disables the asynch behaviour of the control message. This is used for data
 * transfers that uses the exclusiv access to the control and bulk messages.
 * Returns the old value so it can be restored later.
 */
int usb_disable_asynch(int disable)
{
	int old_value = asynch_allowed;

	asynch_allowed = !disable;
	return old_value;
}
#endif /* !CONFIG_DM_USB */


/*-------------------------------------------------------------------
 * Message wrappers.
 *
 */

/*
 * submits an Interrupt Message
 */
int usb_submit_int_msg(struct usb_device *dev, unsigned long pipe,
			void *buffer, int transfer_len, int interval)
{
	return submit_int_msg(dev, pipe, buffer, transfer_len, interval);
}

/*
 * submits a control message and waits for comletion (at least timeout * 1ms)
 * If timeout is 0, we don't wait for completion (used as example to set and
 * clear keyboards LEDs). For data transfers, (storage transfers) we don't
 * allow control messages with 0 timeout, by previousely resetting the flag
 * asynch_allowed (usb_disable_asynch(1)).
 * returns the transfered length if OK or -1 if error. The transfered length
 * and the current status are stored in the dev->act_len and dev->status.
 */
int usb_control_msg(struct usb_device *dev, unsigned int pipe,
			unsigned char request, unsigned char requesttype,
			unsigned short value, unsigned short index,
			void *data, unsigned short size, int timeout)
{
	ALLOC_CACHE_ALIGN_BUFFER(struct devrequest, setup_packet, 1);
	int err;

	if ((timeout == 0) && (!asynch_allowed)) {
		/* request for a asynch control pipe is not allowed */
		return -EINVAL;
	}

	/* set setup command */
	setup_packet->requesttype = requesttype;
	setup_packet->request = request;
	setup_packet->value = cpu_to_le16(value);
	setup_packet->index = cpu_to_le16(index);
	setup_packet->length = cpu_to_le16(size);
	debug("usb_control_msg: request: 0x%X, requesttype: 0x%X, " \
	      "value 0x%X index 0x%X length 0x%X\n",
	      request, requesttype, value, index, size);
	dev->status = USB_ST_NOT_PROC; /*not yet processed */

	err = submit_control_msg(dev, pipe, data, size, setup_packet);
	if (err < 0)
		return err;
	if (timeout == 0)
		return (int)size;

	/*
	 * Wait for status to update until timeout expires, USB driver
	 * interrupt handler may set the status when the USB operation has
	 * been completed.
	 */
	while (timeout--) {
		if (!((volatile unsigned long)dev->status & USB_ST_NOT_PROC))
			break;
		mdelay(1);
	}
	if (dev->status)
		return -1;

	return dev->act_len;

}

/*-------------------------------------------------------------------
 * submits bulk message, and waits for completion. returns 0 if Ok or
 * negative if Error.
 * synchronous behavior
 */
int usb_bulk_msg(struct usb_device *dev, unsigned int pipe,
			void *data, int len, int *actual_length, int timeout)
{
	if (len < 0)
		return -EINVAL;
	dev->status = USB_ST_NOT_PROC; /*not yet processed */
	if (submit_bulk_msg(dev, pipe, data, len) < 0)
		return -EIO;
	while (timeout--) {
		if (!((volatile unsigned long)dev->status & USB_ST_NOT_PROC))
			break;
		mdelay(1);
	}
	*actual_length = dev->act_len;
	if (dev->status == 0)
		return 0;
	else
		return -EIO;
}


/*-------------------------------------------------------------------
 * Max Packet stuff
 */

/*
 * returns the max packet size, depending on the pipe direction and
 * the configurations values
 */
int usb_maxpacket(struct usb_device *dev, unsigned long pipe)
{
	/* direction is out -> use emaxpacket out */
	if ((pipe & USB_DIR_IN) == 0)
		return dev->epmaxpacketout[((pipe>>15) & 0xf)];
	else
		return dev->epmaxpacketin[((pipe>>15) & 0xf)];
}

/*
 * The routine usb_set_maxpacket_ep() is extracted from the loop of routine
 * usb_set_maxpacket(), because the optimizer of GCC 4.x chokes on this routine
 * when it is inlined in 1 single routine. What happens is that the register r3
 * is used as loop-count 'i', but gets overwritten later on.
 * This is clearly a compiler bug, but it is easier to workaround it here than
 * to update the compiler (Occurs with at least several GCC 4.{1,2},x
 * CodeSourcery compilers like e.g. 2007q3, 2008q1, 2008q3 lite editions on ARM)
 *
 * NOTE: Similar behaviour was observed with GCC4.6 on ARMv5.
 */
static void noinline
usb_set_maxpacket_ep(struct usb_device *dev, int if_idx, int ep_idx)
{
	int b;
	struct usb_endpoint_descriptor *ep;
	u16 ep_wMaxPacketSize;

	ep = &dev->config.if_desc[if_idx].ep_desc[ep_idx];

	b = ep->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK;
	ep_wMaxPacketSize = get_unaligned(&ep->wMaxPacketSize);

	if ((ep->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) ==
						USB_ENDPOINT_XFER_CONTROL) {
		/* Control => bidirectional */
		dev->epmaxpacketout[b] = ep_wMaxPacketSize;
		dev->epmaxpacketin[b] = ep_wMaxPacketSize;
		debug("##Control EP epmaxpacketout/in[%d] = %d\n",
		      b, dev->epmaxpacketin[b]);
	} else {
		if ((ep->bEndpointAddress & 0x80) == 0) {
			/* OUT Endpoint */
			if (ep_wMaxPacketSize > dev->epmaxpacketout[b]) {
				dev->epmaxpacketout[b] = ep_wMaxPacketSize;
				debug("##EP epmaxpacketout[%d] = %d\n",
				      b, dev->epmaxpacketout[b]);
			}
		} else {
			/* IN Endpoint */
			if (ep_wMaxPacketSize > dev->epmaxpacketin[b]) {
				dev->epmaxpacketin[b] = ep_wMaxPacketSize;
				debug("##EP epmaxpacketin[%d] = %d\n",
				      b, dev->epmaxpacketin[b]);
			}
		} /* if out */
	} /* if control */
}

/*
 * set the max packed value of all endpoints in the given configuration
 */
static int usb_set_maxpacket(struct usb_device *dev)
{
	int i, ii;

	for (i = 0; i < dev->config.desc.bNumInterfaces; i++)
		for (ii = 0; ii < dev->config.if_desc[i].desc.bNumEndpoints; ii++)
			usb_set_maxpacket_ep(dev, i, ii);

	return 0;
}

/*******************************************************************************
 * Parse the config, located in buffer, and fills the dev->config structure.
 * Note that all little/big endian swapping are done automatically.
 * (wTotalLength has already been swapped and sanitized when it was read.)
 */
static int usb_parse_config(struct usb_device *dev,
			unsigned char *buffer, int cfgno)
{
	struct usb_descriptor_header *head;
	int index, ifno, epno, curr_if_num;
	u16 ep_wMaxPacketSize;
	struct usb_interface *if_desc = NULL;

	ifno = -1;
	epno = -1;
	curr_if_num = -1;

	dev->configno = cfgno;
	head = (struct usb_descriptor_header *) &buffer[0];
	if (head->bDescriptorType != USB_DT_CONFIG) {
		printf(" ERROR: NOT USB_CONFIG_DESC %x\n",
			head->bDescriptorType);
		return -EINVAL;
	}
	if (head->bLength != USB_DT_CONFIG_SIZE) {
		printf("ERROR: Invalid USB CFG length (%d)\n", head->bLength);
		return -EINVAL;
	}
	memcpy(&dev->config, head, USB_DT_CONFIG_SIZE);
	dev->config.no_of_if = 0;

	index = dev->config.desc.bLength;
	/* Ok the first entry must be a configuration entry,
	 * now process the others */
	head = (struct usb_descriptor_header *) &buffer[index];
	while (index + 1 < dev->config.desc.wTotalLength && head->bLength) {
		switch (head->bDescriptorType) {
		case USB_DT_INTERFACE:
			if (head->bLength != USB_DT_INTERFACE_SIZE) {
				printf("ERROR: Invalid USB IF length (%d)\n",
					head->bLength);
				break;
			}
			if (index + USB_DT_INTERFACE_SIZE >
			    dev->config.desc.wTotalLength) {
				puts("USB IF descriptor overflowed buffer!\n");
				break;
			}
			if (((struct usb_interface_descriptor *) \
			     head)->bInterfaceNumber != curr_if_num) {
				/* this is a new interface, copy new desc */
				ifno = dev->config.no_of_if;
				if (ifno >= USB_MAXINTERFACES) {
					puts("Too many USB interfaces!\n");
					/* try to go on with what we have */
					return -EINVAL;
				}
				if_desc = &dev->config.if_desc[ifno];
				dev->config.no_of_if++;
				memcpy(if_desc, head,
					USB_DT_INTERFACE_SIZE);
				if_desc->no_of_ep = 0;
				if_desc->num_altsetting = 1;
				curr_if_num =
				     if_desc->desc.bInterfaceNumber;
			} else {
				/* found alternate setting for the interface */
				if (ifno >= 0) {
					if_desc = &dev->config.if_desc[ifno];
					if_desc->num_altsetting++;
				}
			}
			break;
		case USB_DT_ENDPOINT:
			if (head->bLength != USB_DT_ENDPOINT_SIZE) {
				printf("ERROR: Invalid USB EP length (%d)\n",
					head->bLength);
				break;
			}
			if (index + USB_DT_ENDPOINT_SIZE >
			    dev->config.desc.wTotalLength) {
				puts("USB EP descriptor overflowed buffer!\n");
				break;
			}
			if (ifno < 0) {
				puts("Endpoint descriptor out of order!\n");
				break;
			}
			epno = dev->config.if_desc[ifno].no_of_ep;
			if_desc = &dev->config.if_desc[ifno];
			if (epno > USB_MAXENDPOINTS) {
				printf("Interface %d has too many endpoints!\n",
					if_desc->desc.bInterfaceNumber);
				return -EINVAL;
			}
			/* found an endpoint */
			if_desc->no_of_ep++;
			memcpy(&if_desc->ep_desc[epno], head,
				USB_DT_ENDPOINT_SIZE);
			ep_wMaxPacketSize = get_unaligned(&dev->config.\
							if_desc[ifno].\
							ep_desc[epno].\
							wMaxPacketSize);
			put_unaligned(le16_to_cpu(ep_wMaxPacketSize),
					&dev->config.\
					if_desc[ifno].\
					ep_desc[epno].\
					wMaxPacketSize);
			debug("if %d, ep %d\n", ifno, epno);
			break;
		case USB_DT_SS_ENDPOINT_COMP:
			if (head->bLength != USB_DT_SS_EP_COMP_SIZE) {
				printf("ERROR: Invalid USB EPC length (%d)\n",
					head->bLength);
				break;
			}
			if (index + USB_DT_SS_EP_COMP_SIZE >
			    dev->config.desc.wTotalLength) {
				puts("USB EPC descriptor overflowed buffer!\n");
				break;
			}
			if (ifno < 0 || epno < 0) {
				puts("EPC descriptor out of order!\n");
				break;
			}
			if_desc = &dev->config.if_desc[ifno];
			memcpy(&if_desc->ss_ep_comp_desc[epno], head,
				USB_DT_SS_EP_COMP_SIZE);
			break;
		default:
			if (head->bLength == 0)
				return -EINVAL;

			debug("unknown Description Type : %x\n",
			      head->bDescriptorType);

#ifdef DEBUG
			{
				unsigned char *ch = (unsigned char *)head;
				int i;

				for (i = 0; i < head->bLength; i++)
					debug("%02X ", *ch++);
				debug("\n\n\n");
			}
#endif
			break;
		}
		index += head->bLength;
		head = (struct usb_descriptor_header *)&buffer[index];
	}
	return 0;
}

/***********************************************************************
 * Clears an endpoint
 * endp: endpoint number in bits 0-3;
 * direction flag in bit 7 (1 = IN, 0 = OUT)
 */
int usb_clear_halt(struct usb_device *dev, int pipe)
{
	int result;
	int endp = usb_pipeendpoint(pipe)|(usb_pipein(pipe)<<7);

	result = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
				 USB_REQ_CLEAR_FEATURE, USB_RECIP_ENDPOINT, 0,
				 endp, NULL, 0, USB_CNTL_TIMEOUT * 3);

	/* don't clear if failed */
	if (result < 0)
		return result;

	/*
	 * NOTE: we do not get status and verify reset was successful
	 * as some devices are reported to lock up upon this check..
	 */

	usb_endpoint_running(dev, usb_pipeendpoint(pipe), usb_pipeout(pipe));

	/* toggle is reset on clear */
	usb_settoggle(dev, usb_pipeendpoint(pipe), usb_pipeout(pipe), 0);
	return 0;
}


/**********************************************************************
 * get_descriptor type
 */
static int usb_get_descriptor(struct usb_device *dev, unsigned char type,
			unsigned char index, void *buf, int size)
{
	int res;
	res = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
			USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
			(type << 8) + index, 0,
			buf, size, USB_CNTL_TIMEOUT);
	return res;
}

/**********************************************************************
 * gets configuration cfgno and store it in the buffer
 */
int usb_get_configuration_no(struct usb_device *dev,
			     unsigned char *buffer, int cfgno)
{
	int result;
	unsigned int length;
	struct usb_config_descriptor *config;

	config = (struct usb_config_descriptor *)&buffer[0];
	result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno, buffer, 9);
	if (result < 9) {
		if (result < 0)
			printf("unable to get descriptor, error %lX\n",
				dev->status);
		else
			printf("config descriptor too short " \
				"(expected %i, got %i)\n", 9, result);
		return -EIO;
	}
	length = le16_to_cpu(config->wTotalLength);

	if (length > USB_BUFSIZ) {
		printf("%s: failed to get descriptor - too long: %d\n",
			__func__, length);
		return -EIO;
	}

	result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno, buffer, length);
	debug("get_conf_no %d Result %d, wLength %d\n", cfgno, result, length);
	config->wTotalLength = length; /* validated, with CPU byte order */

	return result;
}

/********************************************************************
 * set address of a device to the value in dev->devnum.
 * This can only be done by addressing the device via the default address (0)
 */
static int usb_set_address(struct usb_device *dev)
{
	int res;

	debug("set address %d\n", dev->devnum);
	res = usb_control_msg(dev, usb_snddefctrl(dev),
				USB_REQ_SET_ADDRESS, 0,
				(dev->devnum), 0,
				NULL, 0, USB_CNTL_TIMEOUT);
	return res;
}

/********************************************************************
 * set interface number to interface
 */
int usb_set_interface(struct usb_device *dev, int interface, int alternate)
{
	struct usb_interface *if_face = NULL;
	int ret, i;

	for (i = 0; i < dev->config.desc.bNumInterfaces; i++) {
		if (dev->config.if_desc[i].desc.bInterfaceNumber == interface) {
			if_face = &dev->config.if_desc[i];
			break;
		}
	}
	if (!if_face) {
		printf("selecting invalid interface %d", interface);
		return -EINVAL;
	}
	/*
	 * We should return now for devices with only one alternate setting.
	 * According to 9.4.10 of the Universal Serial Bus Specification
	 * Revision 2.0 such devices can return with a STALL. This results in
	 * some USB sticks timeouting during initialization and then being
	 * unusable in U-Boot.
	 */
	if (if_face->num_altsetting == 1)
		return 0;

	ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
				USB_REQ_SET_INTERFACE, USB_RECIP_INTERFACE,
				alternate, interface, NULL, 0,
				USB_CNTL_TIMEOUT * 5);
	if (ret < 0)
		return ret;

	return 0;
}

/********************************************************************
 * set configuration number to configuration
 */
static int usb_set_configuration(struct usb_device *dev, int configuration)
{
	int res;
	debug("set configuration %d\n", configuration);
	/* set setup command */
	res = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
				USB_REQ_SET_CONFIGURATION, 0,
				configuration, 0,
				NULL, 0, USB_CNTL_TIMEOUT);
	if (res == 0) {
		dev->toggle[0] = 0;
		dev->toggle[1] = 0;
		return 0;
	} else
		return -EIO;
}

/********************************************************************
 * set protocol to protocol
 */
int usb_set_protocol(struct usb_device *dev, int ifnum, int protocol)
{
	return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
		USB_REQ_SET_PROTOCOL, USB_TYPE_CLASS | USB_RECIP_INTERFACE,
		protocol, ifnum, NULL, 0, USB_CNTL_TIMEOUT);
}

/********************************************************************
 * set idle
 */
int usb_set_idle(struct usb_device *dev, int ifnum, int duration, int report_id)
{
	return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
		USB_REQ_SET_IDLE, USB_TYPE_CLASS | USB_RECIP_INTERFACE,
		(duration << 8) | report_id, ifnum, NULL, 0, USB_CNTL_TIMEOUT);
}

/********************************************************************
 * get report
 */
int usb_get_report(struct usb_device *dev, int ifnum, unsigned char type,
		   unsigned char id, void *buf, int size)
{
	return usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
			USB_REQ_GET_REPORT,
			USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
			(type << 8) + id, ifnum, buf, size, USB_CNTL_TIMEOUT);
}

/********************************************************************
 * get class descriptor
 */
int usb_get_class_descriptor(struct usb_device *dev, int ifnum,
		unsigned char type, unsigned char id, void *buf, int size)
{
	return usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
		USB_REQ_GET_DESCRIPTOR, USB_RECIP_INTERFACE | USB_DIR_IN,
		(type << 8) + id, ifnum, buf, size, USB_CNTL_TIMEOUT);
}

/********************************************************************
 * get string index in buffer
 */
static int usb_get_string(struct usb_device *dev, unsigned short langid,
		   unsigned char index, void *buf, int size)
{
	int i;
	int result;

	for (i = 0; i < 3; ++i) {
		/* some devices are flaky */
		result = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
			USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
			(USB_DT_STRING << 8) + index, langid, buf, size,
			USB_CNTL_TIMEOUT);

		if (result > 0)
			break;
	}

	return result;
}


static void usb_try_string_workarounds(unsigned char *buf, int *length)
{
	int newlength, oldlength = *length;

	for (newlength = 2; newlength + 1 < oldlength; newlength += 2)
		if (!isprint(buf[newlength]) || buf[newlength + 1])
			break;

	if (newlength > 2) {
		buf[0] = newlength;
		*length = newlength;
	}
}


static int usb_string_sub(struct usb_device *dev, unsigned int langid,
		unsigned int index, unsigned char *buf)
{
	int rc;

	/* Try to read the string descriptor by asking for the maximum
	 * possible number of bytes */
	rc = usb_get_string(dev, langid, index, buf, 255);

	/* If that failed try to read the descriptor length, then
	 * ask for just that many bytes */
	if (rc < 2) {
		rc = usb_get_string(dev, langid, index, buf, 2);
		if (rc == 2)
			rc = usb_get_string(dev, langid, index, buf, buf[0]);
	}

	if (rc >= 2) {
		if (!buf[0] && !buf[1])
			usb_try_string_workarounds(buf, &rc);

		/* There might be extra junk at the end of the descriptor */
		if (buf[0] < rc)
			rc = buf[0];

		rc = rc - (rc & 1); /* force a multiple of two */
	}

	if (rc < 2)
		rc = -EINVAL;

	return rc;
}


/********************************************************************
 * usb_string:
 * Get string index and translate it to ascii.
 * returns string length (> 0) or error (< 0)
 */
int usb_string(struct usb_device *dev, int index, char *buf, size_t size)
{
	ALLOC_CACHE_ALIGN_BUFFER(unsigned char, mybuf, USB_BUFSIZ);
	unsigned char *tbuf;
	int err;
	unsigned int u, idx;

	if (size <= 0 || !buf || !index)
		return -EINVAL;
	buf[0] = 0;
	tbuf = &mybuf[0];

	/* get langid for strings if it's not yet known */
	if (!dev->have_langid) {
		err = usb_string_sub(dev, 0, 0, tbuf);
		if (err < 0) {
			debug("error getting string descriptor 0 " \
			      "(error=%lx)\n", dev->status);
			return -EIO;
		} else if (tbuf[0] < 4) {
			debug("string descriptor 0 too short\n");
			return -EIO;
		} else {
			dev->have_langid = -1;
			dev->string_langid = tbuf[2] | (tbuf[3] << 8);
				/* always use the first langid listed */
			debug("USB device number %d default " \
			      "language ID 0x%x\n",
			      dev->devnum, dev->string_langid);
		}
	}

	err = usb_string_sub(dev, dev->string_langid, index, tbuf);
	if (err < 0)
		return err;

	size--;		/* leave room for trailing NULL char in output buffer */
	for (idx = 0, u = 2; u < err; u += 2) {
		if (idx >= size)
			break;
		if (tbuf[u+1])			/* high byte */
			buf[idx++] = '?';  /* non-ASCII character */
		else
			buf[idx++] = tbuf[u];
	}
	buf[idx] = 0;
	err = idx;
	return err;
}


/********************************************************************
 * USB device handling:
 * the USB device are static allocated [USB_MAX_DEVICE].
 */

#ifndef CONFIG_DM_USB

/* returns a pointer to the device with the index [index].
 * if the device is not assigned (dev->devnum==-1) returns NULL
 */
struct usb_device *usb_get_dev_index(int index)
{
	if (usb_dev[index].devnum == -1)
		return NULL;
	else
		return &usb_dev[index];
}

int usb_alloc_new_device(struct udevice *controller, struct usb_device **devp)
{
	int i;
	debug("New Device %d\n", dev_index);
	if (dev_index == USB_MAX_DEVICE) {
		printf("ERROR, too many USB Devices, max=%d\n", USB_MAX_DEVICE);
		return -ENOSPC;
	}
	/* default Address is 0, real addresses start with 1 */
	usb_dev[dev_index].devnum = dev_index + 1;
	usb_dev[dev_index].maxchild = 0;
	for (i = 0; i < USB_MAXCHILDREN; i++)
		usb_dev[dev_index].children[i] = NULL;
	usb_dev[dev_index].parent = NULL;
	usb_dev[dev_index].controller = controller;
	dev_index++;
	*devp = &usb_dev[dev_index - 1];

	return 0;
}

/*
 * Free the newly created device node.
 * Called in error cases where configuring a newly attached
 * device fails for some reason.
 */
void usb_free_device(struct udevice *controller)
{
	dev_index--;
	debug("Freeing device node: %d\n", dev_index);
	memset(&usb_dev[dev_index], 0, sizeof(struct usb_device));
	usb_dev[dev_index].devnum = -1;
}

/*
 * XHCI issues Enable Slot command and thereafter
 * allocates device contexts. Provide a weak alias
 * function for the purpose, so that XHCI overrides it
 * and EHCI/OHCI just work out of the box.
 */
__weak int usb_alloc_device(struct usb_device *udev)
{
	return 0;
}
#endif /* !CONFIG_DM_USB */

#ifndef CONFIG_DM_USB
int usb_legacy_port_reset(struct usb_device *hub, int portnr)
{
	if (hub) {
		unsigned short portstatus;
		int err;

		/* reset the port for the second time */
		err = legacy_hub_port_reset(hub, portnr - 1, &portstatus);
		if (err < 0) {
			printf("\n     Couldn't reset port %i\n", portnr);
			return err;
		}
	} else {
		usb_reset_root_port();
	}

	return 0;
}
#endif

static int get_descriptor_len(struct usb_device *dev, int len, int expect_len)
{
	__maybe_unused struct usb_device_descriptor *desc;
	ALLOC_CACHE_ALIGN_BUFFER(unsigned char, tmpbuf, USB_BUFSIZ);
	int err;

	desc = (struct usb_device_descriptor *)tmpbuf;

	err = usb_get_descriptor(dev, USB_DT_DEVICE, 0, desc, len);
	if (err < expect_len) {
		if (err < 0) {
			printf("unable to get device descriptor (error=%d)\n",
				err);
			return err;
		} else {
			printf("USB device descriptor short read (expected %i, got %i)\n",
				expect_len, err);
			return -EIO;
		}
	}
	memcpy(&dev->descriptor, tmpbuf, sizeof(dev->descriptor));

	return 0;
}

static int usb_setup_descriptor(struct usb_device *dev, bool do_read)
{
	__maybe_unused struct usb_device_descriptor *desc;

	/*
	 * This is a Windows scheme of initialization sequence, with double
	 * reset of the device (Linux uses the same sequence)
	 * Some equipment is said to work only with such init sequence; this
	 * patch is based on the work by Alan Stern:
	 * http://sourceforge.net/mailarchive/forum.php?
	 * thread_id=5729457&forum_id=5398
	 */

	/*
	 * send 64-byte GET-DEVICE-DESCRIPTOR request.  Since the descriptor is
	 * only 18 bytes long, this will terminate with a short packet.  But if
	 * the maxpacket size is 8 or 16 the device may be waiting to transmit
	 * some more, or keeps on retransmitting the 8 byte header.
	 */

	if (dev->speed == USB_SPEED_LOW) {
		dev->descriptor.bMaxPacketSize0 = 8;
		dev->maxpacketsize = PACKET_SIZE_8;
	} else {
		dev->descriptor.bMaxPacketSize0 = 64;
		dev->maxpacketsize = PACKET_SIZE_64;
	}
	dev->epmaxpacketin[0] = dev->descriptor.bMaxPacketSize0;
	dev->epmaxpacketout[0] = dev->descriptor.bMaxPacketSize0;

	if (do_read) {
		int err;

		/*
		 * Validate we've received only at least 8 bytes, not that we've
		 * received the entire descriptor. The reasoning is:
		 * - The code only uses fields in the first 8 bytes, so that's all we
		 *   need to have fetched at this stage.
		 * - The smallest maxpacket size is 8 bytes. Before we know the actual
		 *   maxpacket the device uses, the USB controller may only accept a
		 *   single packet. Consequently we are only guaranteed to receive 1
		 *   packet (at least 8 bytes) even in a non-error case.
		 *
		 * At least the DWC2 controller needs to be programmed with the number
		 * of packets in addition to the number of bytes. A request for 64
		 * bytes of data with the maxpacket guessed as 64 (above) yields a
		 * request for 1 packet.
		 */
		err = get_descriptor_len(dev, 64, 8);
		if (err)
			return err;
	}

	dev->epmaxpacketin[0] = dev->descriptor.bMaxPacketSize0;
	dev->epmaxpacketout[0] = dev->descriptor.bMaxPacketSize0;
	switch (dev->descriptor.bMaxPacketSize0) {
	case 8:
		dev->maxpacketsize  = PACKET_SIZE_8;
		break;
	case 16:
		dev->maxpacketsize = PACKET_SIZE_16;
		break;
	case 32:
		dev->maxpacketsize = PACKET_SIZE_32;
		break;
	case 64:
		dev->maxpacketsize = PACKET_SIZE_64;