jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2022, Jesse Buhagiar <jesse.buhagiar@serenityos.org>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <AK/FixedArray.h>
8#include <Kernel/Bus/USB/USBClasses.h>
9#include <Kernel/Bus/USB/USBConfiguration.h>
10#include <Kernel/Bus/USB/USBInterface.h>
11#include <Kernel/Bus/USB/USBRequest.h>
12#include <Kernel/StdLib.h>
13
14namespace Kernel::USB {
15
16ErrorOr<void> USBConfiguration::enumerate_interfaces()
17{
18 auto descriptor_hierarchy_buffer = TRY(FixedArray<u8>::create(m_descriptor.total_length)); // Buffer for us to store the entire hierarchy into
19
20 // The USB spec is a little bit janky here... Interface and Endpoint descriptors aren't fetched
21 // through a `GET_DESCRIPTOR` request to the device. Instead, the _entire_ hierarchy is returned
22 // to us in one go.
23 auto transfer_length = TRY(m_device.control_transfer(USB_REQUEST_TRANSFER_DIRECTION_DEVICE_TO_HOST, USB_REQUEST_GET_DESCRIPTOR, (DESCRIPTOR_TYPE_CONFIGURATION << 8), 0, m_descriptor.total_length, descriptor_hierarchy_buffer.data()));
24
25 // FIXME: Why does transfer length return the actual size +8 bytes?
26 if (transfer_length < m_descriptor.total_length)
27 return EIO;
28
29 u8* interface_descriptors_base = descriptor_hierarchy_buffer.data() + sizeof(USBConfigurationDescriptor);
30 USBInterfaceDescriptor* interface_descriptor = reinterpret_cast<USBInterfaceDescriptor*>(interface_descriptors_base);
31 Vector<USBEndpointDescriptor> endpoint_descriptors;
32 for (auto interface = 0u; interface < m_descriptor.number_of_interfaces; interface++) {
33 endpoint_descriptors.ensure_capacity(interface_descriptor->number_of_endpoints);
34
35 if constexpr (USB_DEBUG) {
36 dbgln("Interface Descriptor {}", interface);
37 dbgln("interface_id: {:02x}", interface_descriptor->interface_id);
38 dbgln("alternate_setting: {:02x}", interface_descriptor->alternate_setting);
39 dbgln("number_of_endpoints: {:02x}", interface_descriptor->number_of_endpoints);
40 dbgln("interface_class_code: {:02x}", interface_descriptor->interface_class_code);
41 dbgln("interface_sub_class_code: {:02x}", interface_descriptor->interface_sub_class_code);
42 dbgln("interface_protocol: {:02x}", interface_descriptor->interface_protocol);
43 dbgln("interface_string_descriptor_index: {}", interface_descriptor->interface_string_descriptor_index);
44 }
45
46 // Get all the endpoint descriptors
47 for (auto endpoint = 0u; endpoint < interface_descriptor->number_of_endpoints; endpoint++) {
48 u8* raw_endpoint_descriptor_offset = interface_descriptors_base + sizeof(USBInterfaceDescriptor) + (endpoint * sizeof(USBEndpointDescriptor));
49
50 // FIXME: It looks like HID descriptors come BEFORE the endpoint descriptors for a HID device, so we should load
51 // these too eventually.
52 // See here: https://www.usb.org/defined-class-codes
53 if (interface_descriptor->interface_class_code == USB_CLASS_HID)
54 raw_endpoint_descriptor_offset += sizeof(USBHIDDescriptor); // Skip the HID descriptor (this was worked out via buffer inspection)
55
56 USBEndpointDescriptor endpoint_descriptor;
57 memcpy(&endpoint_descriptor, raw_endpoint_descriptor_offset, sizeof(USBEndpointDescriptor));
58
59 if constexpr (USB_DEBUG) {
60 dbgln("Endpoint Descriptor {}", endpoint);
61 dbgln("Endpoint Address: {}", endpoint_descriptor.endpoint_address);
62 dbgln("Endpoint Attribute Bitmap: {:08b}", endpoint_descriptor.endpoint_attributes_bitmap);
63 dbgln("Endpoint Maximum Packet Size: {}", endpoint_descriptor.max_packet_size);
64 dbgln("Endpoint Poll Interval (in frames): {}", endpoint_descriptor.poll_interval_in_frames);
65 }
66
67 endpoint_descriptors.append(endpoint_descriptor);
68 }
69
70 USBInterface device_interface(*this, *interface_descriptor, endpoint_descriptors);
71 m_interfaces.append(device_interface);
72 interface_descriptor += interface_descriptor->number_of_endpoints * sizeof(USBEndpointDescriptor);
73 }
74
75 return {};
76}
77
78}