spapr: split the IRQ allocation sequence

Today, when a device requests for IRQ number in a sPAPR machine, the
spapr_irq_alloc() routine first scans the ICSState status array to
find an empty slot and then performs the assignement of the selected
numbers. Split this sequence in two distinct routines : spapr_irq_find()
for lookups and spapr_irq_claim() for claiming the IRQ numbers.

This will ease the introduction of a static layout of IRQ numbers.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 50 insertions, 0 deletions

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 4a0b679..b7705c3 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -3816,6 +3816,36 @@ static int ics_find_free_block(ICSState *ics, int num, int alignnum)
     return -1;
 }
 
+int spapr_irq_find(sPAPRMachineState *spapr, int num, bool align, Error **errp)
+{
+    ICSState *ics = spapr->ics;
+    int first = -1;
+
+    assert(ics);
+
+    /*
+     * MSIMesage::data is used for storing VIRQ so
+     * it has to be aligned to num to support multiple
+     * MSI vectors. MSI-X is not affected by this.
+     * The hint is used for the first IRQ, the rest should
+     * be allocated continuously.
+     */
+    if (align) {
+        assert((num == 1) || (num == 2) || (num == 4) ||
+               (num == 8) || (num == 16) || (num == 32));
+        first = ics_find_free_block(ics, num, num);
+    } else {
+        first = ics_find_free_block(ics, num, 1);
+    }
+
+    if (first < 0) {
+        error_setg(errp, "can't find a free %d-IRQ block", num);
+        return -1;
+    }
+
+    return first + ics->offset;
+}
+
 /*
  * Allocate the IRQ number and set the IRQ type, LSI or MSI
  */
@@ -3894,6 +3924,26 @@ int spapr_irq_alloc_block(sPAPRMachineState *spapr, int num, bool lsi,
     return first;
 }
 
+int spapr_irq_claim(sPAPRMachineState *spapr, int irq, bool lsi, Error **errp)
+{
+    ICSState *ics = spapr->ics;
+
+    assert(ics);
+
+    if (!ics_valid_irq(ics, irq)) {
+        error_setg(errp, "IRQ %d is invalid", irq);
+        return -1;
+    }
+
+    if (!ICS_IRQ_FREE(ics, irq - ics->offset)) {
+        error_setg(errp, "IRQ %d is not free", irq);
+        return -1;
+    }
+
+    spapr_irq_set_lsi(spapr, irq, lsi);
+    return 0;
+}
+
 void spapr_irq_free(sPAPRMachineState *spapr, int irq, int num)
 {
     ICSState *ics = spapr->ics;