[src/trunk]: src/sys/dev/usb Tidy up a bit. Fulfil requests completely.

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/dfe2a56a2326
branches:  trunk
changeset: 825449:dfe2a56a2326
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sat Jul 15 05:46:09 2017 +0000

description:
Tidy up a bit.  Fulfil requests completely.

diffstat:

 sys/dev/usb/ualea.c |  93 +++++++++++++++++++++++++++++++++++++++-------------
 1 files changed, 70 insertions(+), 23 deletions(-)

diffs (191 lines):

diff -r 60099b1319b1 -r dfe2a56a2326 sys/dev/usb/ualea.c
--- a/sys/dev/usb/ualea.c       Fri Jul 14 23:05:27 2017 +0000
+++ b/sys/dev/usb/ualea.c       Sat Jul 15 05:46:09 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ualea.c,v 1.6 2017/04/19 00:01:38 riastradh Exp $      */
+/*     $NetBSD: ualea.c,v 1.7 2017/07/15 05:46:09 riastradh Exp $      */
 
 /*-
  * Copyright (c) 2017 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ualea.c,v 1.6 2017/04/19 00:01:38 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ualea.c,v 1.7 2017/07/15 05:46:09 riastradh Exp $");
 
 #include <sys/types.h>
 #include <sys/atomic.h>
@@ -47,16 +47,21 @@
 
 struct ualea_softc {
        device_t                sc_dev;
-       struct usbd_device      *sc_udev;
-       struct usbd_interface   *sc_uif;
        kmutex_t                sc_lock;
        krndsource_t            sc_rnd;
        uint16_t                sc_maxpktsize;
        struct usbd_pipe        *sc_pipe;
+       /*
+        * Lock covers:
+        * - sc_needed
+        * - sc_attached
+        * - sc_inflight
+        * - usbd_transfer(sc_xfer)
+        */
        struct usbd_xfer        *sc_xfer;
+       size_t                  sc_needed;
        bool                    sc_attached:1;
        bool                    sc_inflight:1;
-       /* lock covers sc_attached, sc_inflight, and usbd_transfer(sc_xfer) */
 };
 
 static int     ualea_match(device_t, cfdata_t, void *);
@@ -88,28 +93,26 @@
 {
        struct usbif_attach_arg *uiaa = aux;
        struct ualea_softc *sc = device_private(self);
-       struct usbd_device *udev = uiaa->uiaa_device;
-       struct usbd_interface *uif = uiaa->uiaa_iface;
        const usb_endpoint_descriptor_t *ed;
        char *devinfop;
        usbd_status status;
 
+       /* Print the device info.  */
        aprint_naive("\n");
        aprint_normal("\n");
-
-       devinfop = usbd_devinfo_alloc(udev, 0);
+       devinfop = usbd_devinfo_alloc(uiaa->uiaa_device, 0);
        aprint_normal_dev(self, "%s\n", devinfop);
        usbd_devinfo_free(devinfop);
 
+       /* Initialize the softc.  */
        sc->sc_dev = self;
-       sc->sc_udev = udev;
-       sc->sc_uif = uif;
        mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_SOFTUSB);
        rndsource_setcb(&sc->sc_rnd, ualea_get, sc);
        rnd_attach_source(&sc->sc_rnd, device_xname(self), RND_TYPE_RNG,
            RND_FLAG_COLLECT_VALUE|RND_FLAG_HASCB);
 
-       ed = usbd_interface2endpoint_descriptor(uif, 0);
+       /* Get endpoint descriptor 0.  Make sure it's bulk-in.  */
+       ed = usbd_interface2endpoint_descriptor(uiaa->uiaa_iface, 0);
        if (ed == NULL) {
                aprint_error_dev(sc->sc_dev, "failed to read endpoint 0\n");
                return;
@@ -120,9 +123,11 @@
                return;
        }
 
+       /* Remember the maximum packet size.  */
        sc->sc_maxpktsize = UGETW(ed->wMaxPacketSize);
 
-       status = usbd_open_pipe(uif, ed->bEndpointAddress,
+       /* Open an exclusive MP-safe pipe for endpoint 0.  */
+       status = usbd_open_pipe(uiaa->uiaa_iface, ed->bEndpointAddress,
            USBD_EXCLUSIVE_USE|USBD_MPSAFE, &sc->sc_pipe);
        if (status) {
                aprint_error_dev(sc->sc_dev, "failed to open pipe: %d\n",
@@ -130,6 +135,7 @@
                return;
        }
 
+       /* Create an xfer of maximum packet size, short OK, on the pipe.  */
        status = usbd_create_xfer(sc->sc_pipe, sc->sc_maxpktsize,
            USBD_SHORT_XFER_OK, 0, &sc->sc_xfer);
        if (status) {
@@ -138,6 +144,7 @@
                return;
        }
 
+       /* Setup the xfer to call ualea_xfer_done with sc.  */
        usbd_setup_xfer(sc->sc_xfer, sc, usbd_get_buffer(sc->sc_xfer),
            sc->sc_maxpktsize, USBD_SHORT_XFER_OK, USBD_NO_TIMEOUT,
            ualea_xfer_done);
@@ -178,24 +185,56 @@
 }
 
 static void
-ualea_get(size_t nbytes, void *cookie)
+ualea_xfer(struct ualea_softc *sc)
 {
-       struct ualea_softc *sc = cookie;
        usbd_status status;
 
-       mutex_enter(&sc->sc_lock);
-       if (!sc->sc_attached)
-               goto out;
-       if (sc->sc_inflight)
-               goto out;
-       sc->sc_inflight = true;
+       KASSERT(mutex_owned(&sc->sc_lock));
+       KASSERT(sc->sc_attached);
+       KASSERT(!sc->sc_inflight);
+
+       /* Do nothing if we need nothing.  */
+       if (sc->sc_needed == 0)
+               return;
+
+       /* Issue xfer or complain if we can't.  */
+       /*
+        * XXX Does USBD_NORMAL_COMPLETION (= 0) make sense here?  The
+        * xfer can't complete synchronously because of the lock.
+        */
        status = usbd_transfer(sc->sc_xfer);
        if (status && status != USBD_IN_PROGRESS) {
                aprint_error_dev(sc->sc_dev, "failed to issue xfer: %d\n",
                    status);
                /* We failed -- let someone else have a go.  */
-               sc->sc_inflight = false;
+               return;
        }
+
+       /* Mark xfer in-flight.  */
+       sc->sc_inflight = true;
+}
+
+static void
+ualea_get(size_t nbytes, void *cookie)
+{
+       struct ualea_softc *sc = cookie;
+
+       mutex_enter(&sc->sc_lock);
+
+       /* Do nothing if not yet attached.  */
+       if (!sc->sc_attached)
+               goto out;
+
+       /* Update how many bytes we need.  */
+       sc->sc_needed = MAX(sc->sc_needed, nbytes);
+
+       /* Do nothing if xfer is already in flight.  */
+       if (sc->sc_inflight)
+               goto out;
+
+       /* Issue xfer.  */
+       ualea_xfer(sc);
+
 out:   mutex_exit(&sc->sc_lock);
 }
 
@@ -226,9 +265,17 @@
        rnd_add_data(&sc->sc_rnd, pkt, pktsize, NBBY*pktsize);
 
 out:
-       /* Allow subsequent transfers.  */
        mutex_enter(&sc->sc_lock);
+
+       /* Debit what we contributed from what we need.  */
+       sc->sc_needed -= MIN(sc->sc_needed, pktsize);
+
+       /* Mark xfer done.  */
        sc->sc_inflight = false;
+
+       /* Reissue xfer if we still need more.  */
+       ualea_xfer(sc);
+
        mutex_exit(&sc->sc_lock);
 }