usb-host: wire up timer for windows

On windows we can't wait on file descriptors.
Poll libusb using a timer instead.

Fixes long-standing FIXME.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/431
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-Id: <20210623085249.1151901-2-kraxel@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

diff --git a/hw/usb/host-libusb.c b/hw/usb/host-libusb.c
index c0f314462aaf7c16253e5d31e97983ba3b7454e4..00f6fbb29b3922e4b25a0bda4e465d169f73f3a0 100644 (file)
--- a/hw/usb/host-libusb.c
+++ b/hw/usb/host-libusb.c
@@ -254,6 +254,29 @@ static void usb_host_del_fd(int fd, void *user_data)
     qemu_set_fd_handler(fd, NULL, NULL, NULL);
 }
 
+#else
+
+static QEMUTimer *poll_timer;
+static uint32_t request_count;
+
+static void usb_host_timer_kick(void)
+{
+    int64_t delay_ns;
+
+    delay_ns = request_count
+        ? (NANOSECONDS_PER_SECOND / 100)  /* 10 ms interval with active req */
+        : (NANOSECONDS_PER_SECOND);       /* 1 sec interval otherwise */
+    timer_mod(poll_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + delay_ns);
+}
+
+static void usb_host_timer(void *opaque)
+{
+    struct timeval tv = { 0, 0 };
+
+    libusb_handle_events_timeout(ctx, &tv);
+    usb_host_timer_kick();
+}
+
 #endif /* !CONFIG_WIN32 */
 
 static int usb_host_init(void)
@@ -276,7 +299,8 @@ static int usb_host_init(void)
     libusb_set_debug(ctx, loglevel);
 #endif
 #ifdef CONFIG_WIN32
-    /* FIXME: add support for Windows. */
+    poll_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, usb_host_timer, NULL);
+    usb_host_timer_kick();
 #else
     libusb_set_pollfd_notifiers(ctx, usb_host_add_fd,
                                 usb_host_del_fd,
@@ -364,11 +388,18 @@ static USBHostRequest *usb_host_req_alloc(USBHostDevice *s, USBPacket *p,
         r->buffer = g_malloc(bufsize);
     }
     QTAILQ_INSERT_TAIL(&s->requests, r, next);
+#ifdef CONFIG_WIN32
+    request_count++;
+    usb_host_timer_kick();
+#endif
     return r;
 }
 
 static void usb_host_req_free(USBHostRequest *r)
 {
+#ifdef CONFIG_WIN32
+    request_count--;
+#endif
     QTAILQ_REMOVE(&r->host->requests, r, next);
     libusb_free_transfer(r->xfer);
     g_free(r->buffer);