NAME

usb_get_string_descr - Get string descriptor from device

SYNOPSIS

#include <sys/usb/usba.h>
int usb_get_string_descr(dev_info_t *dip,
     uint16_t langid, uint8_t index,
     char *buf, size_t buflen);

INTERFACE LEVEL

illumos DDI specific (illumos DDI)

PARAMETERS

dip

Pointer to the device's dev_info structure.

langid

Language ID. Currently only USB_LANG_ID (English ascii) is valid.

index

String index indicating descriptor to retrieve.

buf

Address into which the string descriptor is placed.

buflen

Size of buf in bytes.

DESCRIPTION

The usb_get_string_descr() function retrieves a parsed string descriptor from a device. dip specifies the device, while index indicates which descriptor to return.

String descriptors provide information about other descriptors, or information that is encoded in other descriptors, in readable form. Many descriptor types have one or more index fields which identify string descriptors. (See Sections 9.5 and 9.6 of the USB 2.0 specification.) For example, a configuration descriptor's seventh byte contains the string descriptor index describing a specific configuration.

Retrieved descriptors that do not fit into buflen bytes are truncated. All returned descriptors are null-terminated.

RETURN VALUES

USB_SUCCESS

String descriptor is returned in buf.

USB_INVALID_ARGS

dip or buf are NULL, or index or buflen is 0.

USB_FAILURE

Descriptor cannot be retrieved.

CONTEXT

May be called from user or kernel context.

EXAMPLES

   /* Get the first string descriptor. */
    char buf[SIZE];
    if (usb_get_string_descr(
        dip, USB_LANG_ID, 0, buf, SIZE) == USB_SUCCESS) {
            cmn_err (CE_NOTE, "%s%d: %s",
                ddi_driver_name(dip), ddi_get_instance(dip), buf);
    }

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Architecture	PCI-based systems
Interface stability	Committed