[PATCH 6.19 321/781] PCI: rzg3s-host: Use pci_generic_config_write() for the root bus

Greg Kroah-Hartman
2026-02-25T01:32:49Z

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

[ Upstream commit 4b86eff47e205819eb862097493ec20e25ac8f56 ]

The Renesas RZ/G3S host controller allows writing to read-only PCIe
configuration registers when the RZG3S_PCI_PERM_CFG_HWINIT_EN bit is set in
the RZG3S_PCI_PERM register. However, callers of struct pci_ops::write
expect the semantics defined by the PCIe specification, meaning that writes
to read-only registers must not be allowed.

The previous custom struct pci_ops::write implementation for the root bus
temporarily enabled write access before calling pci_generic_config_write().
This breaks the expected semantics.

Remove the custom implementation and simply use pci_generic_config_write().

Along with this change, the updates of the PCI_PRIMARY_BUS,
PCI_SECONDARY_BUS, and PCI_SUBORDINATE_BUS registers were moved so that
they no longer depends on the RZG3S_PCI_PERM_CFG_HWINIT_EN bit in the
RZG3S_PCI_PERM_CFG register, since these registers are R/W.

Fixes: 7ef502fb35b2 ("PCI: Add Renesas RZ/G3S host controller driver")
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://patch.msgid.link/20251217111510.138848-2-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/pci/controller/pcie-rzg3s-host.c | 27 ++++--------------------
1 file changed, 4 insertions(+), 23 deletions(-)

diff --git a/drivers/pci/controller/pcie-rzg3s-host.c b/drivers/pci/controller/pcie-rzg3s-host.c
index 83ec66a708236..ae6d9c7dc2c12 100644
--- a/drivers/pci/controller/pcie-rzg3s-host.c
+++ b/drivers/pci/controller/pcie-rzg3s-host.c
@@ -439,28 +439,9 @@ static void __iomem *rzg3s_pcie_root_map_bus(struct pci_bus *bus,
return host->pcie + where;
}

-/* Serialized by 'pci_lock' */
-static int rzg3s_pcie_root_write(struct pci_bus *bus, unsigned int devfn,
- int where, int size, u32 val)
-{
- struct rzg3s_pcie_host *host = bus->sysdata;
- int ret;
-
- /* Enable access control to the CFGU */
- writel_relaxed(RZG3S_PCI_PERM_CFG_HWINIT_EN,
- host->axi + RZG3S_PCI_PERM);
-
- ret = pci_generic_config_write(bus, devfn, where, size, val);
-
- /* Disable access control to the CFGU */
- writel_relaxed(0, host->axi + RZG3S_PCI_PERM);
-
- return ret;
-}
-
static struct pci_ops rzg3s_pcie_root_ops = {
.read = pci_generic_config_read,
- .write = rzg3s_pcie_root_write,
+ .write = pci_generic_config_write,
.map_bus = rzg3s_pcie_root_map_bus,
};

@@ -1065,14 +1046,14 @@ static int rzg3s_pcie_config_init(struct rzg3s_pcie_host *host)
writel_relaxed(0xffffffff, host->pcie + RZG3S_PCI_CFG_BARMSK00L);
writel_relaxed(0xffffffff, host->pcie + RZG3S_PCI_CFG_BARMSK00U);

+ /* Disable access control to the CFGU */
+ writel_relaxed(0, host->axi + RZG3S_PCI_PERM);
+
/* Update bus info */
writeb_relaxed(primary_bus, host->pcie + PCI_PRIMARY_BUS);
writeb_relaxed(secondary_bus, host->pcie + PCI_SECONDARY_BUS);
writeb_relaxed(subordinate_bus, host->pcie + PCI_SUBORDINATE_BUS);

- /* Disable access control to the CFGU */
- writel_relaxed(0, host->axi + RZG3S_PCI_PERM);
-
return 0;
}

--
2.51.0