xics: Implement xics_ics_free()

This implements interrupt release function so IRQs can be returned back
to the pool for reuse in cases such as PCI hot plug.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Alexander Graf <agraf@suse.de>

hw/intc/xics.c

@@ -775,6 +775,33 @@ int xics_alloc_block(XICSState *icp, int src, int num, bool lsi, bool align)
     return first;
 }
 
+static void ics_free(ICSState *ics, int srcno, int num)
+{
+    int i;
+
+    for (i = srcno; i < srcno + num; ++i) {
+        if (ICS_IRQ_FREE(ics, i)) {
+            trace_xics_ics_free_warn(ics - ics->icp->ics, i + ics->offset);
+        }
+        memset(&ics->irqs[i], 0, sizeof(ICSIRQState));
+    }
+}
+
+void xics_free(XICSState *icp, int irq, int num)
+{
+    int src = xics_find_source(icp, irq);
+
+    if (src >= 0) {
+        ICSState *ics = &icp->ics[src];
+
+        /* FIXME: implement multiple sources */
+        assert(src == 0);
+
+        trace_xics_ics_free(ics - icp->ics, irq, num);
+        ics_free(ics, irq - ics->offset, num);
+    }
+}
+
 /*
  * Guest interfaces
  */

include/hw/ppc/xics.h

@@ -162,6 +162,7 @@ qemu_irq xics_get_qirq(XICSState *icp, int irq);
 void xics_set_irq_type(XICSState *icp, int irq, bool lsi);
 int xics_alloc(XICSState *icp, int src, int irq_hint, bool lsi);
 int xics_alloc_block(XICSState *icp, int src, int num, bool lsi, bool align);
+void xics_free(XICSState *icp, int irq, int num);
 
 void xics_cpu_setup(XICSState *icp, PowerPCCPU *cpu);
 

trace-events

@@ -1192,6 +1192,8 @@ xics_alloc(int src, int irq) "source#%d, irq %d"
 xics_alloc_failed_hint(int src, int irq) "source#%d, irq %d is already in use"
 xics_alloc_failed_no_left(int src) "source#%d, no irq left"
 xics_alloc_block(int src, int first, int num, bool lsi, int align) "source#%d, first irq %d, %d irqs, lsi=%d, alignnum %d"
+xics_ics_free(int src, int irq, int num) "Source#%d, first irq %d, %d irqs"
+xics_ics_free_warn(int src, int irq) "Source#%d, irq %d is already free"
 
 # hw/ppc/spapr.c
 spapr_cas_failed(unsigned long n) "DT diff buffer is too small: %ld bytes"