virtio_console: use virtqueue notification for hvc_console

This patch exploits the new notifier callbacks of the hvc_console. We can
use the virtio callbacks instead of the polling code.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 33 insertions, 7 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index dc17fe3a88bc..d0f4eb6fdb7f 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -46,6 +46,9 @@ static char *in, *inbuf;
 /* The operations for our console. */
 static struct hv_ops virtio_cons;
 
+/* The hvc device */
+static struct hvc_struct *hvc;
+
 /*D:310 The put_chars() callback is pretty straightforward.
  *
  * We turn the characters into a scatter-gather list, add it to the output
@@ -134,6 +137,27 @@ int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
         return hvc_instantiate(0, 0, &virtio_cons);
 }
 
+/*
+ * we support only one console, the hvc struct is a global var
+ * There is no need to do anything
+ */
+static int notifier_add_vio(struct hvc_struct *hp, int data)
+{
+        hp->irq_requested = 1;
+        return 0;
+}
+
+static void notifier_del_vio(struct hvc_struct *hp, int data)
+{
+        hp->irq_requested = 0;
+}
+
+static void hvc_handle_input(struct virtqueue *vq)
+{
+        if (hvc_poll(hvc))
+                hvc_kick();
+}
+
 /*D:370 Once we're further in boot, we get probed like any other virtio device.
  * At this stage we set up the output virtqueue.
  *
@@ -144,7 +168,6 @@ int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
 static int __devinit virtcons_probe(struct virtio_device *dev)
 {
         int err;
-        struct hvc_struct *hvc;
 
         vdev = dev;
 
@@ -158,7 +181,7 @@ static int __devinit virtcons_probe(struct virtio_device *dev)
         /* Find the input queue. */
         /* FIXME: This is why we want to wean off hvc: we do nothing
          * when input comes in. */
-        in_vq = vdev->config->find_vq(vdev, 0, NULL);
+        in_vq = vdev->config->find_vq(vdev, 0, hvc_handle_input);
         if (IS_ERR(in_vq)) {
                 err = PTR_ERR(in_vq);
                 goto free;
@@ -173,15 +196,18 @@ static int __devinit virtcons_probe(struct virtio_device *dev)
         /* Start using the new console output. */
         virtio_cons.get_chars = get_chars;
         virtio_cons.put_chars = put_chars;
+        virtio_cons.notifier_add = notifier_add_vio;
+        virtio_cons.notifier_del = notifier_del_vio;
 
         /* The first argument of hvc_alloc() is the virtual console number, so
-         * we use zero.  The second argument is the interrupt number; we
-         * currently leave this as zero: it would be better not to use the
-         * hvc mechanism and fix this (FIXME!).
+         * we use zero.  The second argument is the parameter for the
+         * notification mechanism (like irq number). We currently leave this
+         * as zero, virtqueues have implicit notifications.
          *
          * The third argument is a "struct hv_ops" containing the put_chars()
-         * and get_chars() pointers.  The final argument is the output buffer
-         * size: we can do any size, so we put PAGE_SIZE here. */
+         * get_chars(), notifier_add() and notifier_del() pointers.
+         * The final argument is the output buffer size: we can do any size,
+         * so we put PAGE_SIZE here. */
         hvc = hvc_alloc(0, 0, &virtio_cons, PAGE_SIZE);
         if (IS_ERR(hvc)) {
                 err = PTR_ERR(hvc);