[PATCH v3 5/9] pci: pcie_dw_rockchip: Hide BARs of the root complex

[Jonas Karlman]

PCI Autoconfig read the Root Complex BARs and try to claim the entire
1 GiB memory region on RK3568, leaving no space for any attached device.

With a memory region less than 1 GiB this was not a real issue:

  PCI Autoconfig: Bus Memory region: [0-3eefffff],
  PCI Autoconfig: Bus I/O region: [3ef00000-3effffff],
  PCI Autoconfig: Found P2P bridge, device 0
  PCI Autoconfig: BAR 0, Mem, size=0x40000000, No room in resource, avail start=1000 / size=3ef00000, need=40000000
  PCI: Failed autoconfig bar 10
  PCI Autoconfig: BAR 1, Mem, size=0x40000000, No room in resource, avail start=1000 / size=3ef00000, need=40000000
  PCI: Failed autoconfig bar 14
  PCI Autoconfig: ROM, size=0x10000, address=0x10000 bus_lower=0x20000

  PCI Autoconfig: BAR 0, Mem64, size=0x4000, address=0x100000 bus_lower=0x104000

With a memory region of the entire 1 GiB this leads to:

  PCI Autoconfig: Bus Memory region: [40000000-7fffffff],
  PCI Autoconfig: Bus I/O region: [f0100000-f01fffff],
  PCI Autoconfig: Found P2P bridge, device 0
  PCI Autoconfig: BAR 0, Mem, size=0x40000000, address=0x40000000 bus_lower=0x80000000
  PCI Autoconfig: BAR 1, Mem, size=0x40000000, No room in resource, avail start=80000000 / size=40000000, need=40000000
  PCI: Failed autoconfig bar 14
  PCI Autoconfig: ROM, size=0x10000, No room in resource, avail start=80000000 / size=40000000, need=10000

  PCI Autoconfig: BAR 0, Mem64, size=0x4000, No room in resource, avail start=80000000 / size=40000000, need=4000
  PCI: Failed autoconfig bar 10

After this change with a memory region of the entire 1 GiB:

  PCI Autoconfig: Bus Memory region: [40000000-7fffffff],
  PCI Autoconfig: Bus I/O region: [f0100000-f01fffff],
  PCI Autoconfig: Found P2P bridge, device 0
  PCI Autoconfig: ROM, size=0x10000, address=0x40000000 bus_lower=0x40010000

  PCI Autoconfig: BAR 0, Mem64, size=0x4000, address=0x40100000 bus_lower=0x40104000

Return an invalid value during config read of Root Complex BARs during
autoconfig to work around such issue.

Signed-off-by: Jonas Karlman <jonas at kwiboo.se>
---
v3:
- No change

v2:
- Update commit message

 drivers/pci/pcie_dw_rockchip.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pcie_dw_rockchip.c b/drivers/pci/pcie_dw_rockchip.c
index 82a8b9c96e2b..f56773c2e58c 100644
--- a/drivers/pci/pcie_dw_rockchip.c
+++ b/drivers/pci/pcie_dw_rockchip.c
@@ -146,6 +146,32 @@ static inline void rk_pcie_writel_apb(struct rk_pcie *rk_pcie, u32 reg,
 	__rk_pcie_write_apb(rk_pcie, rk_pcie->apb_base, reg, 0x4, val);
 }
 
+/**
+ * The BARs of bridge should be hidden during enumeration to avoid
+ * allocation of the entire memory region by PCIe core on RK3568.
+ */
+static bool rk_pcie_hide_rc_bar(struct pcie_dw *pcie, pci_dev_t bdf,
+				uint offset)
+{
+	int bus = PCI_BUS(bdf) - pcie->first_busno;
+
+	return bus == 0 && PCI_DEV(bdf) == 0 && PCI_FUNC(bdf) == 0 &&
+	       offset >= PCI_BASE_ADDRESS_0 && offset <= PCI_BASE_ADDRESS_1;
+}
+
+static int rk_pcie_read_config(const struct udevice *bus, pci_dev_t bdf,
+			       uint offset, ulong *valuep,
+			       enum pci_size_t size)
+{
+	struct pcie_dw *pcie = dev_get_priv(bus);
+	int ret = pcie_dw_read_config(bus, bdf, offset, valuep, size);
+
+	if (!ret && rk_pcie_hide_rc_bar(pcie, bdf, offset))
+		*valuep = pci_get_ff(size);
+
+	return ret;
+}
+
 /**
  * rk_pcie_configure() - Configure link capabilities and speed
  *
@@ -476,7 +502,7 @@ rockchip_pcie_probe_err_init_port:
 }
 
 static const struct dm_pci_ops rockchip_pcie_ops = {
-	.read_config	= pcie_dw_read_config,
+	.read_config	= rk_pcie_read_config,
 	.write_config	= pcie_dw_write_config,
 };
 
-- 
2.41.0