USB: redbear-usb-hotplugd — auto-spawn class drivers on device connect
Cross-referenced with Linux 7.1 drivers/usb/core/hub.c port event handling and drivers/usb/core/driver.c device-driver binding. New daemon (216 lines) that watches USB controllers for device attachment/detachment and auto-spawns the appropriate class driver. Architecture: - Polls /scheme/usb/ every 1000ms for controller directories - For each controller, enumerates root hub ports - Reads device descriptors (class/subclass/protocol) via XhciClientHandle - Maps class to driver binary: HID(0x03)→usbhidd, Storage(0x08)→usbscsid, Hub(0x09)→usbhubd - Spawns driver with <scheme> <port> <protocol> arguments - Tracks spawned Child processes in HashMap<port_path, TrackedDevice> - Detects disconnection (descriptor read fails) → kills driver + removes from tracking - Detects driver exit (try_wait) → removes from tracking - Skips hub interfaces (usbhubd handles its own children) Config: - Added to redbear-mini.toml (inherited by redbear-full) - Auto-started via 02_usb_hotplug.service (oneshot_async, after base.target and pcid-spawner) Driver map supports: HID (0x03), Mass Storage (0x08 with BOT protocol), Hub (0x09). Additional class drivers extendable via DRIVER_MAP constant.
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@@ -59,6 +59,7 @@ redbear-acmd = {}
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redbear-ftdi = {}
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redbear-ecmd = {}
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redbear-usbaudiod = {}
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redbear-usb-hotplugd = {}
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driver-params = {}
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# ── PCI device database (critical for PCI driver matching) ──
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@@ -172,6 +173,21 @@ cmd = "audiod"
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type = "oneshot_async"
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"""
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[[files]]
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path = "/etc/init.d/02_usb_hotplug.service"
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data = """
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[unit]
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description = "USB device hotplug daemon (auto-spawns class drivers)"
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requires_weak = [
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"00_base.target",
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"00_pcid-spawner.service",
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]
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[service]
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cmd = "redbear-usb-hotplugd"
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type = "oneshot_async"
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"""
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[[files]]
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path = "/etc/init.d/02_serial_probe.service"
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data = """
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@@ -0,0 +1,3 @@
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[workspace]
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members = ["source"]
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resolver = "3"
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@@ -0,0 +1,8 @@
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[source]
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path = "source"
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[build]
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template = "cargo"
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[package.files]
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"/usr/bin/redbear-usb-hotplugd" = "redbear-usb-hotplugd"
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@@ -0,0 +1,19 @@
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[package]
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name = "redbear-usb-hotplugd"
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version = "0.2.5"
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edition = "2024"
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[[bin]]
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name = "redbear-usb-hotplugd"
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path = "src/main.rs"
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[dependencies]
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log = "0.4"
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redox_syscall = { path = "../../../../../local/sources/syscall" }
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libredox = { path = "../../../../../local/sources/libredox", features = ["call", "std"] }
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xhcid = { path = "../../../../../local/sources/base/drivers/usb/xhcid" }
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common = { path = "../../../../../local/sources/base/drivers/common" }
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[patch.crates-io]
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redox_syscall = { path = "../../../../../local/sources/syscall" }
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libredox = { path = "../../../../../local/sources/libredox" }
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@@ -0,0 +1,216 @@
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//! USB device hotplug daemon.
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//!
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//! Cross-referenced with Linux 7.1 `drivers/usb/core/hub.c` port event
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//! handling and `drivers/usb/core/driver.c` device-driver binding.
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//!
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//! Watches USB controllers for device attachment/detachment events.
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//! When a device connects, reads its class/subclass/protocol from the
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//! device descriptor, maps it to the appropriate class driver binary,
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//! and spawns the driver with the correct scheme + port arguments.
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//! When a device disconnects, terminates the associated driver process.
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use std::collections::HashMap;
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use std::fs;
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use std::process::{Child, Command};
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use std::thread;
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use std::time::Duration;
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use xhcid_interface::XhciClientHandle;
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// USB class → driver binary mapping.
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// Linux 7.1: usb_device_match() → usb_device_driver.id_table.
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// Red Bear: static map in usb-core spawn.rs. Replicated here for the
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// hotplug daemon which runs independently of usb-core.
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const DRIVER_MAP: &[(u8, &str, &[&str])] = &[
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(0x03, "/usr/bin/usbhidd", &[]), // HID
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(0x08, "/usr/bin/usbscsid", &["0x50"]), // Mass Storage (BOT)
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(0x09, "/usr/bin/usbhubd", &[]), // Hub
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];
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const POLL_INTERVAL_MS: u64 = 1000;
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struct TrackedDevice {
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scheme: String,
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port: String,
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child: Child,
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}
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fn find_driver_for_class(class: u8, _subclass: u8, protocol: u8) -> Option<(&'static str, &'static str)> {
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for &(cls, binary, _extra_args) in DRIVER_MAP {
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if cls == class {
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let extra = if protocol == 0x50 { "0x50" } else { "0" };
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return Some((binary, extra));
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}
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}
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None
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}
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fn scan_controllers() -> Vec<(String, String)> {
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let mut controllers = Vec::new();
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if let Ok(dir) = fs::read_dir("/scheme/usb") {
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for entry in dir.flatten() {
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let path = entry.path();
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if path.is_dir() {
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if let Some(name) = path.file_name().and_then(|n| n.to_str()) {
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// Skip class driver scheme symlinks (not controller dirs)
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if name.contains("_xhci") || name.contains("_ehci") || name.contains("_ohci") || name.contains("_uhci") {
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controllers.push((name.to_string(), path.to_str().unwrap_or("").to_string()));
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}
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}
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}
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}
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}
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controllers
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}
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fn scan_ports(_scheme: &str, controller_name: &str) -> Vec<String> {
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let mut ports = Vec::new();
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let path = format!("/scheme/usb/{}", controller_name);
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if let Ok(dir) = fs::read_dir(&path) {
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for entry in dir.flatten() {
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let name = entry.file_name();
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let name_str = name.to_string_lossy();
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if let Some(port_num) = name_str.strip_prefix("port") {
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// Only root ports (no dots = root hub port)
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if !port_num.contains('.') {
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ports.push(format!("{}/{}", path, name_str));
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}
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}
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}
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}
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ports
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}
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fn try_read_descriptors(scheme: &str, _controller_name: &str, port_num: &str) -> Option<(u8, u8, u8)> {
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// Try to open an XhciClientHandle to read device descriptors.
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// Parse port number from the path.
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let port_str = port_num.strip_prefix("port").unwrap_or(port_num);
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let port_id: u8 = port_str.parse().ok()?;
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use xhcid_interface::PortId;
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let pid = PortId { root_hub_port_num: port_id, route_string: 0 };
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match XhciClientHandle::new(scheme.to_string(), pid) {
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Ok(handle) => {
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match handle.get_standard_descs() {
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Ok(desc) => {
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// Find the first non-hub interface class (skip hubs,
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// usbhubd handles its own children).
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for conf in &desc.config_descs {
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for ifd in &conf.interface_descs {
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if ifd.class != 0x09 {
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return Some((ifd.class, ifd.sub_class, ifd.protocol));
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}
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}
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}
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None
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}
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Err(_) => None,
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}
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}
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Err(_) => None,
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}
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}
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fn main() {
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log::set_max_level(log::LevelFilter::Info);
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common::init();
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common::setup_logging("usb", "system", "usb-hotplugd",
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common::output_level(), common::file_level());
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log::info!("USB hotplug daemon started — polling /scheme/usb/ every {}ms", POLL_INTERVAL_MS);
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let mut tracked: HashMap<String, TrackedDevice> = HashMap::new();
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loop {
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let controllers = scan_controllers();
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for (ctrl_name, _ctrl_path) in &controllers {
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// The scheme name passed to class drivers. xhci controllers
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// use the full scheme path (e.g. "usb.0000:00:14.0_xhci").
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let scheme_name = format!("usb.{}", ctrl_name);
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// Scan ports under this controller
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let port_paths = scan_ports(&scheme_name, ctrl_name);
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for port_path in &port_paths {
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let port_key = port_path.clone();
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// Already tracking this port?
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if tracked.contains_key(&port_key) {
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continue;
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}
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// Extract port number from path
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let port_num = port_path.rsplit('/').next().unwrap_or("");
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if port_num.is_empty() || !port_num.starts_with("port") {
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continue;
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}
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// Try to read device descriptors
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if let Some((class, subclass, protocol)) = try_read_descriptors(&scheme_name, ctrl_name, port_num) {
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log::info!("New USB device on {}: class={:02X} subclass={:02X} protocol={:02X}",
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port_path, class, subclass, protocol);
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if let Some((driver_binary, extra_arg)) = find_driver_for_class(class, subclass, protocol) {
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let port_str = port_num.strip_prefix("port").unwrap_or(port_num);
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log::info!("Spawning {} for {} on {} port {}", driver_binary, port_path, scheme_name, port_str);
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match Command::new(driver_binary)
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.arg(&scheme_name)
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.arg(port_str)
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.arg(extra_arg)
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.stdin(std::process::Stdio::null())
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.spawn()
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{
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Ok(child) => {
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tracked.insert(port_key.clone(), TrackedDevice {
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scheme: scheme_name.clone(),
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port: port_str.to_string(),
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child,
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});
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}
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Err(e) => {
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log::warn!("Failed to spawn {} for {}: {}", driver_binary, port_path, e);
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}
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}
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}
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}
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}
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}
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// Check for disconnected devices: try to read port status.
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// If a previously-tracked port no longer has a connected device,
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// kill the driver and remove it from tracking.
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let mut disconnected: Vec<String> = Vec::new();
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for (port_key, tracked_dev) in &mut tracked {
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match tracked_dev.child.try_wait() {
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Ok(Some(status)) => {
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log::info!("Driver for {} exited with status {:?}", port_key, status);
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disconnected.push(port_key.clone());
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}
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Ok(None) => {
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// Driver still running. Check if device is still present.
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// We use a simple heuristic: if the descriptors can no
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// longer be read, the device is gone.
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let scheme = tracked_dev.scheme.clone();
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let port_num = format!("port{}", tracked_dev.port);
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let ctrl_name = port_key.split('/').nth(3).unwrap_or("");
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if try_read_descriptors(&scheme, ctrl_name, &port_num).is_none() {
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log::info!("Device disconnected from {}", port_key);
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let _ = tracked_dev.child.kill();
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disconnected.push(port_key.clone());
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}
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}
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Err(e) => {
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log::warn!("Error checking driver for {}: {}", port_key, e);
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}
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}
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}
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for key in &disconnected {
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tracked.remove(key);
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}
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thread::sleep(Duration::from_millis(POLL_INTERVAL_MS));
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}
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}
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+1
@@ -0,0 +1 @@
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../../local/recipes/system/redbear-usb-hotplugd
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Reference in New Issue
Block a user