From de239d043fbfddbcb509e64186f963697127983e Mon Sep 17 00:00:00 2001
From: Keir Fraser <keir.fraser@citrix.com>
Date: Mon, 12 May 2008 10:10:03 +0100
Subject: pvfb/ioemu: transmit refresh interval advice from backend to frontend
 which permits the frontend to avoid useless polls.

Signed-off-by: Samuel Thibault <samuel.thibault@eu.citrix.com>
---
 extras/mini-os/fbfront.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

(limited to 'extras/mini-os/fbfront.c')

diff --git a/extras/mini-os/fbfront.c b/extras/mini-os/fbfront.c
index 3a361b829c..d5acadf085 100644
--- a/extras/mini-os/fbfront.c
+++ b/extras/mini-os/fbfront.c
@@ -255,13 +255,57 @@ struct fbfront_dev {
     int offset;
 
     xenbus_event_queue events;
+
+#ifdef HAVE_LIBC
+    int fd;
+#endif
 };
 
 void fbfront_handler(evtchn_port_t port, struct pt_regs *regs, void *data)
 {
+#ifdef HAVE_LIBC
+    struct fbfront_dev *dev = data;
+    int fd = dev->fd;
+
+    files[fd].read = 1;
+#endif
     wake_up(&fbfront_queue);
 }
 
+int fbfront_receive(struct fbfront_dev *dev, union xenfb_in_event *buf, int n)
+{
+    struct xenfb_page *page = dev->page;
+    uint32_t prod, cons;
+    int i;
+
+#ifdef HAVE_LIBC
+    files[dev->fd].read = 0;
+    mb(); /* Make sure to let the handler set read to 1 before we start looking at the ring */
+#endif
+
+    prod = page->in_prod;
+
+    if (prod == page->in_cons)
+        return 0;
+
+    rmb();      /* ensure we see ring contents up to prod */
+
+    for (i = 0, cons = page->in_cons; i < n && cons != prod; i++, cons++)
+        memcpy(buf + i, &XENFB_IN_RING_REF(page, cons), sizeof(*buf));
+
+    mb();       /* ensure we got ring contents */
+    page->in_cons = cons;
+    notify_remote_via_evtchn(dev->evtchn);
+
+#ifdef HAVE_LIBC
+    if (cons != prod)
+        /* still some events to read */
+        files[dev->fd].read = 1;
+#endif
+
+    return i;
+}
+
 struct fbfront_dev *init_fbfront(char *nodename, unsigned long *mfns, int width, int height, int depth, int stride, int n)
 {
     xenbus_transaction_t xbt;
@@ -482,3 +526,14 @@ void shutdown_fbfront(struct fbfront_dev *dev)
     free(dev->backend);
     free(dev);
 }
+
+#ifdef HAVE_LIBC
+int fbfront_open(struct fbfront_dev *dev)
+{
+    dev->fd = alloc_fd(FTYPE_FB);
+    printk("fb_open(%s) -> %d\n", dev->nodename, dev->fd);
+    files[dev->fd].fb.dev = dev;
+    return dev->fd;
+}
+#endif
+
-- 
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