Change in coreboot[master]: device/pci_device.c: Improve pci_bridge_route() readability

[Felix Held (Code Review)]

Felix Held has submitted this change. ( https://review.coreboot.org/c/coreboot/+/59131 )

Change subject: device/pci_device.c: Improve pci_bridge_route() readability
......................................................................

device/pci_device.c: Improve pci_bridge_route() readability

Both the secondary and subordinate bus numbers are configured in this
function but it's not easy to search for in the tree as the PCI writes
are hidden inside a bigger write to 'PCI_PRIMARY_BUS'. Use separate
variables and PCI config writes to improve the readability.

Change-Id: I3bafd6a2e1d3a0b8d1d43997868a787ce3940ca9
Signed-off-by: Arthur Heymans 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59131
Tested-by: build bot (Jenkins) 
Reviewed-by: Nico Huber 
---
M src/device/pci_device.c
1 file changed, 13 insertions(+), 13 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Nico Huber: Looks good to me, approved

diff --git a/src/device/pci_device.c b/src/device/pci_device.c
index 82494b9..22ccf59 100644
--- a/src/device/pci_device.c
+++ b/src/device/pci_device.c
@@ -1499,7 +1499,7 @@
 {
    struct device *dev = link->dev;
    struct bus *parent = dev->bus;
-	u32 reg, buses = 0;
+	uint8_t primary, secondary, subordinate;

if (state == PCI_ROUTE_SCAN) {
    	link->secondary = parent->subordinate + 1;
@@ -1507,15 +1507,17 @@
    }

if (state == PCI_ROUTE_CLOSE) {
-		buses |= 0xfeff << 8;
+		primary = 0;
+		secondary = 0xff;
+		subordinate = 0xfe;
    } else if (state == PCI_ROUTE_SCAN) {
-		buses |= parent->secondary & 0xff;
-		buses |= ((u32) link->secondary & 0xff) << 8;
-		buses |= 0xff << 16; /* MAX PCI_BUS number here */
+		primary = parent->secondary;
+		secondary = link->secondary;
+		subordinate = 0xff; /* MAX PCI_BUS number here */
    } else if (state == PCI_ROUTE_FINAL) {
-		buses |= parent->secondary & 0xff;
-		buses |= ((u32) link->secondary & 0xff) << 8;
-		buses |= ((u32) link->subordinate & 0xff) << 16;
+		primary = parent->secondary;
+		secondary = link->secondary;
+		subordinate = link->subordinate;
    }

if (state == PCI_ROUTE_SCAN) {
@@ -1530,11 +1532,9 @@
     * transactions will not be propagated by the bridge if it is not
     * correctly configured.
     */
-
-	reg = pci_read_config32(dev, PCI_PRIMARY_BUS);
-	reg &= 0xff000000;
-	reg |= buses;
-	pci_write_config32(dev, PCI_PRIMARY_BUS, reg);
+	pci_write_config8(dev, PCI_PRIMARY_BUS, primary);
+	pci_write_config8(dev, PCI_SECONDARY_BUS, secondary);
+	pci_write_config8(dev, PCI_SUBORDINATE_BUS, subordinate);

if (state == PCI_ROUTE_FINAL) {
    	pci_write_config16(dev, PCI_COMMAND, link->bridge_cmd);