Commit 4b86eff4 authored by Claudiu Beznea's avatar Claudiu Beznea Committed by Manivannan Sadhasivam
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PCI: rzg3s-host: Use pci_generic_config_write() for the root bus 



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: 7ef502fb ("PCI: Add Renesas RZ/G3S host controller driver")
Suggested-by: default avatarBjorn Helgaas <helgaas@kernel.org>
Signed-off-by: default avatarClaudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Signed-off-by: default avatarManivannan Sadhasivam <mani@kernel.org>
Tested-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://patch.msgid.link/20251217111510.138848-2-claudiu.beznea.uj@bp.renesas.com
parent 8f0b4cce

drivers/pci/controller/pcie-rzg3s-host.c

+4 −23
Original line number Diff line number Diff line
@@ -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;

}