USB: core: add helpers to retrieve endpoints
Many USB drivers iterate over the available endpoints to find required endpoints of a specific type and direction. Typically the endpoints are required for proper function and a missing endpoint should abort probe. To facilitate code reuse, add a helper to retrieve common endpoints (bulk or interrupt, in or out) and four wrappers to find a single endpoint. Note that the helpers are marked as __must_check to serve as a reminder to always verify that all expected endpoints are indeed present. This also means that any optional endpoints, typically need to be looked up through separate calls. Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -75,6 +75,89 @@ MODULE_PARM_DESC(autosuspend, "default autosuspend delay");
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#endif
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/**
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* usb_find_common_endpoints() -- look up common endpoint descriptors
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* @alt: alternate setting to search
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* @bulk_in: pointer to descriptor pointer, or NULL
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* @bulk_out: pointer to descriptor pointer, or NULL
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* @int_in: pointer to descriptor pointer, or NULL
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* @int_out: pointer to descriptor pointer, or NULL
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*
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* Search the alternate setting's endpoint descriptors for the first bulk-in,
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* bulk-out, interrupt-in and interrupt-out endpoints and return them in the
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* provided pointers (unless they are NULL).
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*
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* If a requested endpoint is not found, the corresponding pointer is set to
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* NULL.
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*
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* Return: Zero if all requested descriptors were found, or -ENXIO otherwise.
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*/
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int usb_find_common_endpoints(struct usb_host_interface *alt,
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struct usb_endpoint_descriptor **bulk_in,
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struct usb_endpoint_descriptor **bulk_out,
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struct usb_endpoint_descriptor **int_in,
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struct usb_endpoint_descriptor **int_out)
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{
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struct usb_endpoint_descriptor *epd;
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int i;
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if (bulk_in)
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*bulk_in = NULL;
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if (bulk_out)
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*bulk_out = NULL;
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if (int_in)
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*int_in = NULL;
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if (int_out)
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*int_out = NULL;
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for (i = 0; i < alt->desc.bNumEndpoints; ++i) {
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epd = &alt->endpoint[i].desc;
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switch (usb_endpoint_type(epd)) {
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case USB_ENDPOINT_XFER_BULK:
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if (usb_endpoint_dir_in(epd)) {
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if (bulk_in && !*bulk_in) {
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*bulk_in = epd;
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break;
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}
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} else {
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if (bulk_out && !*bulk_out) {
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*bulk_out = epd;
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break;
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}
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}
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continue;
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case USB_ENDPOINT_XFER_INT:
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if (usb_endpoint_dir_in(epd)) {
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if (int_in && !*int_in) {
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*int_in = epd;
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break;
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}
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} else {
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if (int_out && !*int_out) {
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*int_out = epd;
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break;
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}
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}
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continue;
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default:
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continue;
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}
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if ((!bulk_in || *bulk_in) &&
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(!bulk_out || *bulk_out) &&
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(!int_in || *int_in) &&
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(!int_out || *int_out)) {
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return 0;
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}
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}
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return -ENXIO;
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}
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EXPORT_SYMBOL_GPL(usb_find_common_endpoints);
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/**
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* usb_find_alt_setting() - Given a configuration, find the alternate setting
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* for the given interface.
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@ -99,6 +99,41 @@ enum usb_interface_condition {
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USB_INTERFACE_UNBINDING,
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};
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int __must_check
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usb_find_common_endpoints(struct usb_host_interface *alt,
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struct usb_endpoint_descriptor **bulk_in,
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struct usb_endpoint_descriptor **bulk_out,
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struct usb_endpoint_descriptor **int_in,
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struct usb_endpoint_descriptor **int_out);
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static inline int __must_check
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usb_find_bulk_in_endpoint(struct usb_host_interface *alt,
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struct usb_endpoint_descriptor **bulk_in)
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{
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return usb_find_common_endpoints(alt, bulk_in, NULL, NULL, NULL);
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}
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static inline int __must_check
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usb_find_bulk_out_endpoint(struct usb_host_interface *alt,
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struct usb_endpoint_descriptor **bulk_out)
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{
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return usb_find_common_endpoints(alt, NULL, bulk_out, NULL, NULL);
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}
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static inline int __must_check
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usb_find_int_in_endpoint(struct usb_host_interface *alt,
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struct usb_endpoint_descriptor **int_in)
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{
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return usb_find_common_endpoints(alt, NULL, NULL, int_in, NULL);
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}
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static inline int __must_check
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usb_find_int_out_endpoint(struct usb_host_interface *alt,
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struct usb_endpoint_descriptor **int_out)
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{
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return usb_find_common_endpoints(alt, NULL, NULL, NULL, int_out);
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}
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/**
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* struct usb_interface - what usb device drivers talk to
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* @altsetting: array of interface structures, one for each alternate
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