From: Marek Behún kabel@kernel.org
commit 39bd54d43b3f8b3c7b3a75f5d868d8bb858860e7 upstream.
This reverts commit 239edf686c14a9ff926dec2f350289ed7adfefe2.
239edf686c14 ("PCI: aardvark: Fix support for PCI_ROM_ADDRESS1 on emulated bridge") added support for the Type 1 Expansion ROM BAR at config offset 0x38, based on the register being listed in the Marvell Armada A3720 spec. But the spec doesn't document it at all for RC mode, and there is no ROM in the SOC, so remove this emulation for now.
The PCI bridge which represents aardvark's PCIe Root Port has an Expansion ROM Base Address register at offset 0x30, but its meaning is different than PCI's Expansion ROM BAR register, although the layout is the same. (This is why we thought it does the same thing.)
First: there is no ROM (or part of BootROM) in the A3720 SOC dedicated for PCIe Root Port (or controller in RC mode) containing executable code that would initialize the Root Port, suitable for execution in bootloader (this is how Expansion ROM BAR is used on x86).
Second: in A3720 spec the register (address 0xD0070030) is not documented at all for Root Complex mode, but similar to other BAR registers, it has an "entangled partner" in register 0xD0075920, which does address translation for the BAR in 0xD0070030:
- the BAR register sets the address from the view of PCIe bus
- the translation register sets the address from the view of the CPU
The other BAR registers also have this entangled partner, and they can be used to:
- in RC mode: address-checking on the receive side of the RC (they can define address ranges for memory accesses from remote Endpoints to the RC)
- in Endpoint mode: allow the remote CPU to access memory on A3720
The Expansion ROM BAR has only the Endpoint part documented, but from the similarities we think that it can also be used in RC mode in that way.
So either Expansion ROM BAR has different meaning (if the hypothesis above is true), or we don't know it's meaning (since it is not documented for RC mode).
Remove the register from the emulated bridge accessing functions.
[bhelgaas: summarize reason for removal (first paragraph)] Fixes: 239edf686c14 ("PCI: aardvark: Fix support for PCI_ROM_ADDRESS1 on emulated bridge") Link: https://lore.kernel.org/r/20211125160148.26029-3-kabel@kernel.org Signed-off-by: Marek Behún kabel@kernel.org Signed-off-by: Bjorn Helgaas bhelgaas@google.com Reviewed-by: Pali Rohár pali@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/pci/controller/pci-aardvark.c | 9 --------- 1 file changed, 9 deletions(-)
--- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -32,7 +32,6 @@ #define PCIE_CORE_DEV_ID_REG 0x0 #define PCIE_CORE_CMD_STATUS_REG 0x4 #define PCIE_CORE_DEV_REV_REG 0x8 -#define PCIE_CORE_EXP_ROM_BAR_REG 0x30 #define PCIE_CORE_PCIEXP_CAP 0xc0 #define PCIE_CORE_ERR_CAPCTL_REG 0x118 #define PCIE_CORE_ERR_CAPCTL_ECRC_CHK_TX BIT(5) @@ -774,10 +773,6 @@ advk_pci_bridge_emul_base_conf_read(stru *value = advk_readl(pcie, PCIE_CORE_CMD_STATUS_REG); return PCI_BRIDGE_EMUL_HANDLED;
- case PCI_ROM_ADDRESS1: - *value = advk_readl(pcie, PCIE_CORE_EXP_ROM_BAR_REG); - return PCI_BRIDGE_EMUL_HANDLED; - case PCI_INTERRUPT_LINE: { /* * From the whole 32bit register we support reading from HW only @@ -810,10 +805,6 @@ advk_pci_bridge_emul_base_conf_write(str advk_writel(pcie, new, PCIE_CORE_CMD_STATUS_REG); break;
- case PCI_ROM_ADDRESS1: - advk_writel(pcie, new, PCIE_CORE_EXP_ROM_BAR_REG); - break; - case PCI_INTERRUPT_LINE: if (mask & (PCI_BRIDGE_CTL_BUS_RESET << 16)) { u32 val = advk_readl(pcie, PCIE_CORE_CTRL1_REG);