Add gadget initialization to the qdbd daemon

It's not possible to deterministically control timings of gadget
initialization from an external script. Moved gadget initialization
logic from /usr/bin/qdbd-init.sh to the qdbd USB gadget
initialization. This was causing problems when qdbd daemon launch
was delayed because of kernel random pool initialization.

Done-with: Kari Oikarinen <kari.oikarinen@qt.io>
Task-number: QTBUG-63029
Change-Id: Ia403fbe6ebdbc83908bafb023a88fff058efc840
Reviewed-by: Sami Nurmenniemi <sami.nurmenniemi@qt.io>
Reviewed-by: Samuli Piippo <samuli.piippo@qt.io>

4 files changed, 52 insertions, 0 deletions

diff --git a/qdbd/configuration.cpp b/qdbd/configuration.cpp
index b53defb..9ae452c 100644
--- a/qdbd/configuration.cpp
+++ b/qdbd/configuration.cpp
@@ -50,6 +50,11 @@ QString Configuration::rndisFunctionName()
     return s_rndisFunctionName;
 }
 
+QString Configuration::udcDriverDir()
+{
+    return s_udcDriverDir;
+}
+
 void Configuration::setFunctionFsDir(const QString &path)
 {
     s_functionFsDir = QDir::cleanPath(path);
@@ -74,3 +79,4 @@ QString Configuration::s_functionFsDir = "/dev/usb-ffs/qdb";
 QString Configuration::s_gadgetConfigFsDir = "/sys/kernel/config/usb_gadget/g1";
 QString Configuration::s_rndisFunctionName = "rndis.usb0";
 QString Configuration::s_networkScript = "b2qt-gadget-network.sh";
+QString Configuration::s_udcDriverDir = "/sys/class/udc/";
diff --git a/qdbd/configuration.h b/qdbd/configuration.h
index eb34cd7..dadc2c0 100644
--- a/qdbd/configuration.h
+++ b/qdbd/configuration.h
@@ -38,6 +38,7 @@ public:
     static QString gadgetConfigFsDir();
     static QString networkScript();
     static QString rndisFunctionName();
+    static QString udcDriverDir();
     static void setFunctionFsDir(const QString &path);
     static void setGadgetConfigFsDir(const QString &path);
     static void setNetworkScript(const QString &script);
@@ -48,6 +49,7 @@ private:
     static QString s_gadgetConfigFsDir;
     static QString s_networkScript;
     static QString s_rndisFunctionName;
+    static QString s_udcDriverDir;
 };
 
 #endif // CONFIGURATION_H
diff --git a/qdbd/usb-gadget/usbgadget.cpp b/qdbd/usb-gadget/usbgadget.cpp
index 020b293..599de48 100644
--- a/qdbd/usb-gadget/usbgadget.cpp
+++ b/qdbd/usb-gadget/usbgadget.cpp
@@ -40,6 +40,8 @@
 #include <QtCore/qloggingcategory.h>
 #include <QtCore/qthread.h>
 
+#include <QDirIterator>
+
 #include <linux/usb/functionfs.h>
 
 Q_LOGGING_CATEGORY(usbC, "qdb.usb");
@@ -186,6 +188,7 @@ bool UsbGadget::open(QIODevice::OpenMode mode)
     startControlThread();
     startReadThread();
     startWriteThread();
+    initializeGadgetWithUdc();
 
     return true;
 }
@@ -271,3 +274,43 @@ bool UsbGadget::openControlEndpoint()
     return true;
 }
 
+/**
+ * Initialize usb gadget with the first UDC driver
+ */
+void UsbGadget::initializeGadgetWithUdc()
+{
+    QString driverName = []() {
+        QDirIterator it(Configuration::udcDriverDir());
+        while (it.hasNext()) {
+            it.next();
+            const QString candidate = it.fileName();
+            if (candidate != QLatin1String(".") && candidate != QLatin1String(".."))
+                return candidate;
+        }
+        return QString{};
+    }();
+    if (driverName.isEmpty()) {
+        qCCritical(usbC) << "Failed to initialize USB gadget, no UDC drivers found in"
+                         << Configuration::udcDriverDir();
+        return;
+    }
+
+    const QString gadgetConfigPath = Configuration::gadgetConfigFsDir() + QLatin1String("/UDC");
+    QFile gadgetConfigFile{gadgetConfigPath};
+    if (!gadgetConfigFile.exists()) {
+        qCCritical(usbC) << "Failed to initialize USB gadget, no gadget file found in"
+                         << gadgetConfigPath;
+        return;
+    }
+    if (!gadgetConfigFile.open(QIODevice::ReadWrite | QIODevice::Unbuffered)) {
+        qCCritical(usbC) << "Failed to initialize USB gadget, can't open" << gadgetConfigPath;
+        return;
+    }
+    if (gadgetConfigFile.write(driverName.toUtf8()) == -1) {
+        qCCritical(usbC) << "Failed to initialize USB gadget, can't write to"
+                         << gadgetConfigPath;
+        return;
+    }
+    gadgetConfigFile.close();
+    qCDebug(usbC) << "Initialized USB gadget UDC driver";
+}
diff --git a/qdbd/usb-gadget/usbgadget.h b/qdbd/usb-gadget/usbgadget.h
index 857f213..afae869 100644
--- a/qdbd/usb-gadget/usbgadget.h
+++ b/qdbd/usb-gadget/usbgadget.h
@@ -68,6 +68,7 @@ private:
     void startControlThread();
     void startReadThread();
     void startWriteThread();
+    void initializeGadgetWithUdc();
 
     QFile m_controlEndpoint;
     // Endpoints are named in line with USB terminology. Out means from host to