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PCI: endpoint: Describe reserved subregions within BARs

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Some endpoint controllers expose platform-owned, fixed register windows
within a BAR that EPF drivers must not reprogram (e.g. a BAR marked
BAR_RESERVED). Even in that case, EPF drivers may need to reference a
well-defined subset of that BAR, e.g. to reuse an integrated DMA
controller MMIO window as a doorbell target.

Introduce struct pci_epc_bar_rsvd_region and extend struct
pci_epc_bar_desc so EPC drivers can advertise such fixed subregions in a
controller-agnostic way.

No functional change for existing users.

Signed-off-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Tested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Tested-by: Koichiro Den <den@valinux.co.jp>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260312130229.2282001-15-cassel@kernel.org
This commit is contained in:
Koichiro Den 2026-03-12 14:02:31 +01:00 committed by Manivannan Sadhasivam
parent 27ce1d8ecb
commit f51644eb40
1 changed files with 28 additions and 0 deletions
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28
include/linux/pci-epc.h
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@ -200,6 +200,30 @@ enum pci_epc_bar_type {
BAR_RESERVED,
};
/**
* enum pci_epc_bar_rsvd_region_type - type of a fixed subregion behind a BAR
* @PCI_EPC_BAR_RSVD_DMA_CTRL_MMIO: Integrated DMA controller MMIO window
*
* BARs marked BAR_RESERVED are owned by the SoC/EPC hardware and must not be
* reprogrammed by EPF drivers. Some of them still expose fixed subregions that
* EPFs may want to reference (e.g. embedded doorbell fallback).
*/
enum pci_epc_bar_rsvd_region_type {
PCI_EPC_BAR_RSVD_DMA_CTRL_MMIO = 0,
};
/**
* struct pci_epc_bar_rsvd_region - fixed subregion behind a BAR
* @type: reserved region type
* @offset: offset within the BAR aperture
* @size: size of the reserved region
*/
struct pci_epc_bar_rsvd_region {
enum pci_epc_bar_rsvd_region_type type;
resource_size_t offset;
resource_size_t size;
};
/**
* struct pci_epc_bar_desc - hardware description for a BAR
* @type: the type of the BAR
@ -207,11 +231,15 @@ enum pci_epc_bar_type {
* @only_64bit: if true, an EPF driver is not allowed to choose if this BAR
* should be configured as 32-bit or 64-bit, the EPF driver must
* configure this BAR as 64-bit.
* @nr_rsvd_regions: number of fixed subregions described for BAR_RESERVED
* @rsvd_regions: fixed subregions behind BAR_RESERVED
*/
struct pci_epc_bar_desc {
enum pci_epc_bar_type type;
u64 fixed_size;
bool only_64bit;
u8 nr_rsvd_regions;
const struct pci_epc_bar_rsvd_region *rsvd_regions;
};
/**