diff options
Diffstat (limited to 'drivers/usb/core/usb.c')
| -rw-r--r-- | drivers/usb/core/usb.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c index d1e9440..99e5458 100644 --- a/drivers/usb/core/usb.c +++ b/drivers/usb/core/usb.c @@ -64,6 +64,43 @@ MODULE_PARM_DESC(autosuspend, "default autosuspend delay"); /** + * usb_find_alt_setting() - Given a configuration, find the alternate setting + * for the given interface. + * @config - the configuration to search (not necessarily the current config). + * @iface_num - interface number to search in + * @alt_num - alternate interface setting number to search for. + * + * Search the configuration's interface cache for the given alt setting. + */ +struct usb_host_interface *usb_find_alt_setting( + struct usb_host_config *config, + unsigned int iface_num, + unsigned int alt_num) +{ + struct usb_interface_cache *intf_cache = NULL; + int i; + + for (i = 0; i < config->desc.bNumInterfaces; i++) { + if (config->intf_cache[i]->altsetting[0].desc.bInterfaceNumber + == iface_num) { + intf_cache = config->intf_cache[i]; + break; + } + } + if (!intf_cache) + return NULL; + for (i = 0; i < intf_cache->num_altsetting; i++) + if (intf_cache->altsetting[i].desc.bAlternateSetting == alt_num) + return &intf_cache->altsetting[i]; + + printk(KERN_DEBUG "Did not find alt setting %u for intf %u, " + "config %u\n", alt_num, iface_num, + config->desc.bConfigurationValue); + return NULL; +} +EXPORT_SYMBOL_GPL(usb_find_alt_setting); + +/** * usb_ifnum_to_if - get the interface object with a given interface number * @dev: the device whose current configuration is considered * @ifnum: the desired interface |