[Qemu-devel] [RFT][PATCH 07/15] qemu_irq: Add IRQ handlers with delivery feedback

[Jan Kiszka]

From: Jan Kiszka <address@hidden>

This allows to communicate potential IRQ coalescing during delivery from
the sink back to the source. Targets that support IRQ coalescing
workarounds need to register handlers that return the appropriate
QEMU_IRQ_* code, and they have to propergate the code across all IRQ
redirections. If the IRQ source receives a QEMU_IRQ_COALESCED, it can
apply its workaround. If multiple sinks exist, the source may only
consider an IRQ coalesced if all other sinks either report
QEMU_IRQ_COALESCED as well or QEMU_IRQ_MASKED.

Signed-off-by: Jan Kiszka <address@hidden>
---
 hw/irq.c |   38 +++++++++++++++++++++++++++++---------
 hw/irq.h |   22 +++++++++++++++-------
 2 files changed, 44 insertions(+), 16 deletions(-)

diff --git a/hw/irq.c b/hw/irq.c
index 7703f62..db2cce6 100644
--- a/hw/irq.c
+++ b/hw/irq.c
@@ -26,19 +26,27 @@
 
 struct IRQState {
     qemu_irq_handler handler;
+    qemu_irq_fb_handler feedback_handler;
     void *opaque;
     int n;
 };
 
-void qemu_set_irq(qemu_irq irq, int level)
+int qemu_set_irq(qemu_irq irq, int level)
 {
-    if (!irq)
-        return;
-
-    irq->handler(irq->opaque, irq->n, level);
+    if (!irq) {
+        return 0;
+    }
+    if (irq->feedback_handler) {
+        return irq->feedback_handler(irq->opaque, irq->n, level);
+    } else {
+        irq->handler(irq->opaque, irq->n, level);
+        return QEMU_IRQ_DELIVERED;
+    }
 }
 
-qemu_irq *qemu_allocate_irqs(qemu_irq_handler handler, void *opaque, int n)
+static qemu_irq *allocate_irqs(qemu_irq_handler handler,
+                               qemu_irq_fb_handler feedback_handler,
+                               void *opaque, int n)
 {
     qemu_irq *s;
     struct IRQState *p;
@@ -48,6 +56,7 @@ qemu_irq *qemu_allocate_irqs(qemu_irq_handler handler, void 
*opaque, int n)
     p = (struct IRQState *)qemu_mallocz(sizeof(struct IRQState) * n);
     for (i = 0; i < n; i++) {
         p->handler = handler;
+        p->feedback_handler = feedback_handler;
         p->opaque = opaque;
         p->n = i;
         s[i] = p;
@@ -56,22 +65,33 @@ qemu_irq *qemu_allocate_irqs(qemu_irq_handler handler, void 
*opaque, int n)
     return s;
 }
 
+qemu_irq *qemu_allocate_irqs(qemu_irq_handler handler, void *opaque, int n)
+{
+    return allocate_irqs(handler, NULL, opaque, n);
+}
+
+qemu_irq *qemu_allocate_feedback_irqs(qemu_irq_fb_handler handler,
+                                      void *opaque, int n)
+{
+    return allocate_irqs(NULL, handler, opaque, n);
+}
+
 void qemu_free_irqs(qemu_irq *s)
 {
     qemu_free(s[0]);
     qemu_free(s);
 }
 
-static void qemu_notirq(void *opaque, int line, int level)
+static int qemu_notirq(void *opaque, int line, int level)
 {
     struct IRQState *irq = opaque;
 
-    irq->handler(irq->opaque, irq->n, !level);
+    return qemu_set_irq(irq, !level);
 }
 
 qemu_irq qemu_irq_invert(qemu_irq irq)
 {
     /* The default state for IRQs is low, so raise the output now.  */
     qemu_irq_raise(irq);
-    return qemu_allocate_irqs(qemu_notirq, irq, 1)[0];
+    return allocate_irqs(NULL, qemu_notirq, irq, 1)[0];
 }
diff --git a/hw/irq.h b/hw/irq.h
index 5daae44..eee03e6 100644
--- a/hw/irq.h
+++ b/hw/irq.h
@@ -3,15 +3,18 @@
 
 /* Generic IRQ/GPIO pin infrastructure.  */
 
-/* FIXME: Rmove one of these.  */
+#define QEMU_IRQ_DELIVERED      0
+#define QEMU_IRQ_COALESCED      (-1)
+#define QEMU_IRQ_MASKED         (-2)
+
 typedef void (*qemu_irq_handler)(void *opaque, int n, int level);
-typedef void SetIRQFunc(void *opaque, int irq_num, int level);
+typedef int (*qemu_irq_fb_handler)(void *opaque, int n, int level);
 
-void qemu_set_irq(qemu_irq irq, int level);
+int qemu_set_irq(qemu_irq irq, int level);
 
-static inline void qemu_irq_raise(qemu_irq irq)
+static inline int qemu_irq_raise(qemu_irq irq)
 {
-    qemu_set_irq(irq, 1);
+    return qemu_set_irq(irq, 1);
 }
 
 static inline void qemu_irq_lower(qemu_irq irq)
@@ -19,14 +22,19 @@ static inline void qemu_irq_lower(qemu_irq irq)
     qemu_set_irq(irq, 0);
 }
 
-static inline void qemu_irq_pulse(qemu_irq irq)
+static inline int qemu_irq_pulse(qemu_irq irq)
 {
-    qemu_set_irq(irq, 1);
+    int ret;
+
+    ret = qemu_set_irq(irq, 1);
     qemu_set_irq(irq, 0);
+    return ret;
 }
 
 /* Returns an array of N IRQs.  */
 qemu_irq *qemu_allocate_irqs(qemu_irq_handler handler, void *opaque, int n);
+qemu_irq *qemu_allocate_feedback_irqs(qemu_irq_fb_handler handler,
+                                      void *opaque, int n);
 void qemu_free_irqs(qemu_irq *s);
 
 /* Returns a new IRQ with opposite polarity.  */
-- 
1.6.0.2