PPC: e500: pci: Export slot2irq calculation

We need the calculation method to get from a PCI slot ID to its respective
interrupt line twice. Once in the internal map function and once when
assembling the device tree.

So let's extract the calculation to a separate function that can be called
by both users.
Signed-off-by: NAlexander Graf <agraf@suse.de>

hw/ppc/e500.c

@@ -34,6 +34,7 @@
 #include "hw/sysbus.h"
 #include "exec-memory.h"
 #include "host-utils.h"
+#include "hw/ppce500_pci.h"
 
 #define BINARY_DEVICE_TREE_FILE    "mpc8544ds.dtb"
 #define UIMAGE_LOAD_BASE           0
@@ -72,6 +73,7 @@ static uint32_t *pci_map_create(void *fdt, uint32_t mpic, int first_slot,
     int i = 0;
     int slot;
     int pci_irq;
+    int host_irq;
     int last_slot = first_slot + nr_slots;
     uint32_t *pci_map;
 
@@ -85,7 +87,8 @@ static uint32_t *pci_map_create(void *fdt, uint32_t mpic, int first_slot,
             pci_map[i++] = cpu_to_be32(0x0);
             pci_map[i++] = cpu_to_be32(pci_irq + 1);
             pci_map[i++] = cpu_to_be32(mpic);
-            pci_map[i++] = cpu_to_be32(((pci_irq + slot) % 4) + 1);
+            host_irq = ppce500_pci_map_irq_slot(slot, pci_irq);
+            pci_map[i++] = cpu_to_be32(host_irq + 1);
             pci_map[i++] = cpu_to_be32(0x1);
         }
     }

hw/ppce500_pci.c

@@ -19,6 +19,7 @@
 #include "pci.h"
 #include "pci_host.h"
 #include "bswap.h"
+#include "ppce500_pci.h"
 
 #ifdef DEBUG_PCI
 #define pci_debug(fmt, ...) fprintf(stderr, fmt, ## __VA_ARGS__)
@@ -256,7 +257,7 @@ static int mpc85xx_pci_map_irq(PCIDevice *pci_dev, int irq_num)
     int devno = pci_dev->devfn >> 3;
     int ret;
 
-    ret = (irq_num + devno) % 4;
+    ret = ppce500_pci_map_irq_slot(devno, irq_num);
 
     pci_debug("%s: devfn %x irq %d -> %d  devno:%x\n", __func__,
            pci_dev->devfn, irq_num, ret, devno);

hw/ppce500_pci.h

+#ifndef PPCE500_PCI_H
+#define PPCE500_PCI_H
+
+static inline int ppce500_pci_map_irq_slot(int devno, int irq_num)
+{
+    return (devno + irq_num) % 4;
+}
+
+#endif