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node-feature-discovery/source/internal/usb_utils.go

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usb: Add support for USB device discovery This builds on the PCI support to enable the discovery of USB devices. This is primarily intended to be used for the discovery of Edge-based heterogeneous accelerators that are connected via USB, such as the Coral USB Accelerator and the Intel NCS2 - our main motivation for adding this capability to NFD, and as part of our work in the SODALITE H2020 project. USB devices may define their base class at either the device or interface levels. In the case where no device class is set, the per-device interfaces are enumerated instead. USB devices may furthermore have multiple interfaces, which may or may not use the identical class across each interface. We therefore report device existence for each unique class definition to enable more fine-grained labelling and node selection. The default labelling format includes the class, vendor and device (product) IDs, as follows: feature.node.kubernetes.io/usb-fe_1a6e_089a.present=true As with PCI, a subset of device classes are whitelisted for matching. By default, there are only a subset of device classes under which accelerators tend to be mapped, which is used as the basis for the whitelist. These are: - Video - Miscellaneous - Application Specific - Vendor Specific For those interested in matching other classes, this may be extended by using the UsbId rule provided through the custom source. A full list of class codes is provided by the USB-IF at: https://www.usb.org/defined-class-codes For the moment, owing to a lack of a demonstrable use case, neither the subclass nor the protocol information are exposed. If this becomes necessary, support for these attributes can be trivially added. Signed-off-by: Paul Mundt <paul.mundt@adaptant.io>
2020-05-14 22:32:55 +02:00
/*
Copyright 2020 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package busutils
import (
"fmt"
"io/ioutil"
"log"
"path"
"path/filepath"
"strings"
)
type UsbDeviceInfo map[string]string
type UsbClassMap map[string]UsbDeviceInfo
var DefaultUsbDevAttrs = []string{"class", "vendor", "device"}
// The USB device sysfs files do not have terribly user friendly names, map
// these for consistency with the PCI matcher.
var devAttrFileMap = map[string]string{
"class": "bDeviceClass",
"device": "idProduct",
"vendor": "idVendor",
}
func readSingleUsbSysfsAttribute(path string) (string, error) {
data, err := ioutil.ReadFile(path)
if err != nil {
return "", fmt.Errorf("failed to read device attribute %s: %v", filepath.Base(path), err)
}
attrVal := strings.TrimSpace(string(data))
return attrVal, nil
}
// Read a single USB device attribute
// A USB attribute in this context, maps to the corresponding sysfs file
func readSingleUsbAttribute(devPath string, attrName string) (string, error) {
return readSingleUsbSysfsAttribute(path.Join(devPath, devAttrFileMap[attrName]))
}
// Read information of one USB device
func readUsbDevInfo(devPath string, deviceAttrSpec map[string]bool) (UsbClassMap, error) {
classmap := UsbClassMap{}
info := UsbDeviceInfo{}
for attr, _ := range deviceAttrSpec {
attrVal, _ := readSingleUsbAttribute(devPath, attr)
if len(attrVal) > 0 {
info[attr] = attrVal
}
}
// USB devices encode their class information either at the device or the interface level. If the device class
// is set, return as-is.
if info["class"] != "00" {
classmap[info["class"]] = info
} else {
// Otherwise, if a 00 is presented at the device level, descend to the interface level.
interfaces, err := filepath.Glob(devPath + "/*/bInterfaceClass")
if err != nil {
return classmap, err
}
// A device may, notably, have multiple interfaces with mixed classes, so we create a unique device for each
// unique interface class.
for _, intf := range interfaces {
// Determine the interface class
attrVal, err := readSingleUsbSysfsAttribute(intf)
if err != nil {
return classmap, err
}
attr := UsbDeviceInfo{}
for k, v := range info {
attr[k] = v
}
attr["class"] = attrVal
classmap[attrVal] = attr
}
}
return classmap, nil
}
// List available USB devices and retrieve device attributes.
// deviceAttrSpec is a map which specifies which attributes to retrieve.
// a false value for a specific attribute marks the attribute as optional.
// a true value for a specific attribute marks the attribute as mandatory.
// "class" attribute is considered mandatory.
// DetectUsb() will fail if the retrieval of a mandatory attribute fails.
func DetectUsb(deviceAttrSpec map[string]bool) (map[string][]UsbDeviceInfo, error) {
// Unlike PCI, the USB sysfs interface includes entries not just for
// devices. We work around this by globbing anything that includes a
// valid product ID.
const devicePath = "/sys/bus/usb/devices/*/idProduct"
devInfo := make(map[string][]UsbDeviceInfo)
devices, err := filepath.Glob(devicePath)
if err != nil {
return nil, err
}
// "class" is a mandatory attribute, inject it to spec if needed.
deviceAttrSpec["class"] = true
// Iterate over devices
for _, device := range devices {
devMap, err := readUsbDevInfo(filepath.Dir(device), deviceAttrSpec)
if err != nil {
log.Print(err)
continue
}
for class, info := range devMap {
devInfo[class] = append(devInfo[class], info)
}
}
return devInfo, nil
}