sb/intel/bd82x6x: Improve SLCAP

- Use pci_find_capability() and defines from pci_def.h
- Set the 'Hotplug Capable' bit and 'Hot Plug Surprise' bit in SLCAP
  for hotplugable PCIe slots.
- Assign unique slot number and set power limit for PCIe root ports
  that have a slot connected. For integrated devices clear slot number
  and power limit.

Test: System still boots and all PCIe devices are working.

Change-Id: I03aeb0a1ff0041901acc20fe700d3f7995d22366
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78228
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

1 files changed, 27 insertions, 6 deletions

diff --git a/src/southbridge/intel/bd82x6x/pcie.c b/src/southbridge/intel/bd82x6x/pcie.c
index 206894d8a4..da6e007501 100644
--- a/src/southbridge/intel/bd82x6x/pcie.c
+++ b/src/southbridge/intel/bd82x6x/pcie.c
@@ -42,8 +42,10 @@ static bool pci_is_hotplugable(struct device *dev)
 static void pch_pcie_pm_early(struct device *dev)
 {
 	u16 link_width_p0, link_width_p4;
+	struct device *child = NULL;
 	u8 slot_power_limit = 10; /* 10W for x1 */
-	u32 reg32;
+	static u8 slot_number = 1;
+	u32 reg32, cap;
 	u8 reg8;
 
 	reg32 = RCBA32(RPC);
@@ -136,12 +138,31 @@ static void pch_pcie_pm_early(struct device *dev)
 	}
 	pci_write_config32(dev, 0x4c, reg32);
 
+	/*
+	 * PCI device enumeration hasn't started yet, thus any downstream device here
+	 * must be a static device from devicetree.cb.
+	 * If one is found assume it's an integrated device and not a PCIe slot.
+	 */
+	if (dev->link_list)
+		child = pcidev_path_behind(dev->link_list, PCI_DEVFN(0, 0));
+
 	/* Set slot power limit as configured above */
-	reg32 = pci_read_config32(dev, 0x54);
-	reg32 &= ~((1 << 15) | (1 << 16)); /* 16:15 = Slot power scale */
-	reg32 &= ~(0xff << 7);             /* 14:7  = Slot power limit */
-	reg32 |= (slot_power_limit << 7);
-	pci_write_config32(dev, 0x54, reg32);
+	cap = pci_find_capability(dev, PCI_CAP_ID_PCIE);
+
+	reg32 = pci_read_config32(dev, cap + PCI_EXP_SLTCAP);
+	if (pci_is_hotplugable(dev))
+		reg32 |= (PCI_EXP_SLTCAP_HPS | PCI_EXP_SLTCAP_HPC);
+	else
+		reg32 &= ~(PCI_EXP_SLTCAP_HPS | PCI_EXP_SLTCAP_HPC);
+	reg32 &= ~PCI_EXP_SLTCAP_SPLS; /* 16:15 = Slot power scale */
+	reg32 &= ~PCI_EXP_SLTCAP_SPLV; /* 14:7  = Slot power limit */
+	reg32 &= ~PCI_EXP_SLTCAP_PSN;
+	if (!child || !child->on_mainboard) {
+		/* Only PCIe slots have a power limit and slot number */
+		reg32 |= (slot_power_limit << 7);
+		reg32 |= (slot_number++ << 19);
+	}
+	pci_write_config32(dev, cap + PCI_EXP_SLTCAP, reg32);
 }
 
 static void pch_pcie_pm_late(struct device *dev)