[PATCH] pci-host-ecam-generic: access config space independent of system-wide bus id

[Vladimir Oltean]

From: Vladimir Oltean <vladimir.oltean at nxp.com>

The pci-host-ecam-generic code assumes that the ECAM is the first PCI
bus in the system to be probed. Therefore, the system-wide bus number
allocated by U-Boot in sequence for it is going to be zero, which
corresponds to the memory-mapped config spaces found within it.

Reuse the logic from other PCI bus drivers, and assume that U-Boot will
allocate bus numbers in sequence for all buses within the current ECAM.
So the base number of the bus needs to be subtracted when indexing the
correct config space.

Fixes: 3675cb044e68 ("PCI: Add driver for a 'pci-host-ecam-generic' host controller")
Signed-off-by: Vladimir Oltean <vladimir.oltean at nxp.com>
---
 drivers/pci/pcie_ecam_generic.c | 36 +++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/pcie_ecam_generic.c b/drivers/pci/pcie_ecam_generic.c
index 00644edd2646..190919d26a67 100644
--- a/drivers/pci/pcie_ecam_generic.c
+++ b/drivers/pci/pcie_ecam_generic.c
@@ -19,6 +19,8 @@
  */
 struct generic_ecam_pcie {
 	void *cfg_base;
+	pci_size_t size;
+	int first_busno;
 };
 
 /**
@@ -42,7 +44,7 @@ static int pci_generic_ecam_conf_address(struct udevice *bus, pci_dev_t bdf,
 	void *addr;
 
 	addr = pcie->cfg_base;
-	addr += PCI_BUS(bdf) << 20;
+	addr += (PCI_BUS(bdf) - pcie->first_busno) << 20;
 	addr += PCI_DEV(bdf) << 15;
 	addr += PCI_FUNC(bdf) << 12;
 	addr += offset;
@@ -51,6 +53,15 @@ static int pci_generic_ecam_conf_address(struct udevice *bus, pci_dev_t bdf,
 	return 0;
 }
 
+static bool pci_generic_ecam_addr_valid(struct udevice *bus, pci_dev_t bdf)
+{
+	struct generic_ecam_pcie *pcie = dev_get_priv(bus);
+	int num_buses = DIV_ROUND_UP(pcie->size, 1 << 16);
+
+	return (PCI_BUS(bdf) >= pcie->first_busno &&
+		PCI_BUS(bdf) < pcie->first_busno + num_buses);
+}
+
 /**
  * pci_generic_ecam_read_config() - Read from configuration space
  * @bus: Pointer to the PCI bus
@@ -67,6 +78,11 @@ static int pci_generic_ecam_read_config(struct udevice *bus, pci_dev_t bdf,
 				   uint offset, ulong *valuep,
 				   enum pci_size_t size)
 {
+	if (!pci_generic_ecam_addr_valid(bus, bdf)) {
+		*valuep = pci_get_ff(size);
+		return 0;
+	}
+
 	return pci_generic_mmap_read_config(bus, pci_generic_ecam_conf_address,
 					    bdf, offset, valuep, size);
 }
@@ -87,6 +103,9 @@ static int pci_generic_ecam_write_config(struct udevice *bus, pci_dev_t bdf,
 				    uint offset, ulong value,
 				    enum pci_size_t size)
 {
+	if (!pci_generic_ecam_addr_valid(bus, bdf))
+		return 0;
+
 	return pci_generic_mmap_write_config(bus, pci_generic_ecam_conf_address,
 					     bdf, offset, value, size);
 }
@@ -115,9 +134,17 @@ static int pci_generic_ecam_ofdata_to_platdata(struct udevice *dev)
 		return err;
 	}
 
-	pcie->cfg_base = map_physmem(reg_res.start,
-				     fdt_resource_size(&reg_res),
-				     MAP_NOCACHE);
+	pcie->size = fdt_resource_size(&reg_res);
+	pcie->cfg_base = map_physmem(reg_res.start, pcie->size, MAP_NOCACHE);
+
+	return 0;
+}
+
+static int pci_generic_ecam_probe(struct udevice *dev)
+{
+	struct generic_ecam_pcie *pcie = dev_get_priv(dev);
+
+	pcie->first_busno = dev->seq;
 
 	return 0;
 }
@@ -137,6 +164,7 @@ U_BOOT_DRIVER(pci_generic_ecam) = {
 	.id			= UCLASS_PCI,
 	.of_match		= pci_generic_ecam_ids,
 	.ops			= &pci_generic_ecam_ops,
+	.probe			= pci_generic_ecam_probe,
 	.ofdata_to_platdata	= pci_generic_ecam_ofdata_to_platdata,
 	.priv_auto_alloc_size	= sizeof(struct generic_ecam_pcie),
 };
-- 
2.17.1