[PATCH v3 0/9] PCI: endpoint: Differentiate between disabled and reserved BARs

[PATCH v3 0/9] PCI: endpoint: Differentiate between disabled and reserved BARs

[Niklas Cassel]

Hello all,

This series was originally written in response to the patch series from
Manikanta Maddireddy that was posted here:
https://lore.kernel.org/linux-pci/291dab65-3fa6-4fc8-90a2-4ad608ca015c@nvidia.com/T/#t

Manikanta has reviewed V1 and will send a small series on top of this one.


Changes since v2:
-Picked up tags from Frank and Koichiro (thank you)
-Fixed a comment in pcie-dw-rockchip.c to no longer reflect the old
 definition of BAR_RESERVED.

Link to v2:
https://lore.kernel.org/linux-pci/20260225170324.4033466-11-cassel@kernel.org/


Koichiro Den (2):
  PCI: endpoint: Describe reserved subregions within BARs
  PCI: dw-rockchip: Describe RK3588 BAR4 DMA ctrl window

Niklas Cassel (7):
  PCI: endpoint: Introduce pci_epc_bar_type BAR_64BIT_UPPER
  PCI: endpoint: Introduce pci_epc_bar_type BAR_DISABLED
  PCI: dwc: Replace certain BAR_RESERVED with BAR_DISABLED in glue
    drivers
  PCI: dwc: Disable BARs in common code instead of in each glue driver
  PCI: endpoint: pci-epf-test: Advertise reserved BARs
  misc: pci_endpoint_test: Give reserved BARs a distinct error code
  selftests: pci_endpoint: Skip reserved BARs

 drivers/misc/pci_endpoint_test.c              | 21 ++++++++-
 drivers/pci/controller/dwc/pci-dra7xx.c       |  4 --
 drivers/pci/controller/dwc/pci-imx6.c         | 22 +++------
 drivers/pci/controller/dwc/pci-keystone.c     | 12 +++++
 .../pci/controller/dwc/pci-layerscape-ep.c    |  8 +---
 drivers/pci/controller/dwc/pcie-artpec6.c     |  4 --
 .../pci/controller/dwc/pcie-designware-ep.c   | 24 ++++++++++
 .../pci/controller/dwc/pcie-designware-plat.c | 10 -----
 drivers/pci/controller/dwc/pcie-dw-rockchip.c | 23 ++++++----
 drivers/pci/controller/dwc/pcie-keembay.c     |  6 +--
 drivers/pci/controller/dwc/pcie-qcom-ep.c     | 14 +-----
 drivers/pci/controller/dwc/pcie-rcar-gen4.c   | 16 ++-----
 drivers/pci/controller/dwc/pcie-stm32-ep.c    | 10 -----
 drivers/pci/controller/dwc/pcie-tegra194.c    | 20 +++------
 drivers/pci/controller/dwc/pcie-uniphier-ep.c | 24 +++-------
 drivers/pci/controller/pcie-rcar-ep.c         |  6 +--
 drivers/pci/endpoint/functions/pci-epf-test.c | 24 ++++++++++
 drivers/pci/endpoint/pci-epc-core.c           |  6 ++-
 include/linux/pci-epc.h                       | 45 +++++++++++++++++--
 .../pci_endpoint/pci_endpoint_test.c          |  4 ++
 20 files changed, 175 insertions(+), 128 deletions(-)


base-commit: 36bfc3642b19a98f1302aed4437c331df9b481f0
-- 
2.53.0

[PATCH v3 1/9] PCI: endpoint: Introduce pci_epc_bar_type BAR_64BIT_UPPER

[Niklas Cassel]

Add a pci_epc_bar_type BAR_64BIT_UPPER to more clearly differentiate from
BAR_RESERVED.

This BAR type will only be used for a BAR following a "only_64bit" BAR.

This makes the BAR description more clear, and the reader does no longer
need to check the BAR type for the preceding BAR to know how to interpret
the BAR type.

No functional changes.

Tested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Tested-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/controller/dwc/pci-layerscape-ep.c |  4 ++--
 drivers/pci/controller/dwc/pcie-keembay.c      |  6 +++---
 drivers/pci/controller/dwc/pcie-qcom-ep.c      |  4 ++--
 drivers/pci/controller/dwc/pcie-tegra194.c     |  2 +-
 drivers/pci/controller/dwc/pcie-uniphier-ep.c  | 10 +++++-----
 drivers/pci/controller/pcie-rcar-ep.c          |  6 +++---
 drivers/pci/endpoint/pci-epc-core.c            |  3 ++-
 include/linux/pci-epc.h                        |  5 ++++-
 8 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-layerscape-ep.c b/drivers/pci/controller/dwc/pci-layerscape-ep.c
index a4a800699f89..5a03a8f895f9 100644
--- a/drivers/pci/controller/dwc/pci-layerscape-ep.c
+++ b/drivers/pci/controller/dwc/pci-layerscape-ep.c
@@ -251,9 +251,9 @@ static int __init ls_pcie_ep_probe(struct platform_device *pdev)
 	pci->ops = pcie->drvdata->dw_pcie_ops;
 
 	ls_epc->bar[BAR_2].only_64bit = true;
-	ls_epc->bar[BAR_3].type = BAR_RESERVED;
+	ls_epc->bar[BAR_3].type = BAR_64BIT_UPPER;
 	ls_epc->bar[BAR_4].only_64bit = true;
-	ls_epc->bar[BAR_5].type = BAR_RESERVED;
+	ls_epc->bar[BAR_5].type = BAR_64BIT_UPPER;
 	ls_epc->linkup_notifier = true;
 
 	pcie->pci = pci;
diff --git a/drivers/pci/controller/dwc/pcie-keembay.c b/drivers/pci/controller/dwc/pcie-keembay.c
index 2666a9c3d67e..5a00b8cf5b53 100644
--- a/drivers/pci/controller/dwc/pcie-keembay.c
+++ b/drivers/pci/controller/dwc/pcie-keembay.c
@@ -313,11 +313,11 @@ static const struct pci_epc_features keembay_pcie_epc_features = {
 	.msi_capable		= true,
 	.msix_capable		= true,
 	.bar[BAR_0]		= { .only_64bit = true, },
-	.bar[BAR_1]		= { .type = BAR_RESERVED, },
+	.bar[BAR_1]		= { .type = BAR_64BIT_UPPER, },
 	.bar[BAR_2]		= { .only_64bit = true, },
-	.bar[BAR_3]		= { .type = BAR_RESERVED, },
+	.bar[BAR_3]		= { .type = BAR_64BIT_UPPER, },
 	.bar[BAR_4]		= { .only_64bit = true, },
-	.bar[BAR_5]		= { .type = BAR_RESERVED, },
+	.bar[BAR_5]		= { .type = BAR_64BIT_UPPER, },
 	.align			= SZ_16K,
 };
 
diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index 18460f01b2c6..e55675b3840a 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -850,9 +850,9 @@ static const struct pci_epc_features qcom_pcie_epc_features = {
 	.msi_capable = true,
 	.align = SZ_4K,
 	.bar[BAR_0] = { .only_64bit = true, },
-	.bar[BAR_1] = { .type = BAR_RESERVED, },
+	.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
 	.bar[BAR_2] = { .only_64bit = true, },
-	.bar[BAR_3] = { .type = BAR_RESERVED, },
+	.bar[BAR_3] = { .type = BAR_64BIT_UPPER, },
 };
 
 static const struct pci_epc_features *
diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 06571d806ab3..31aa9a494dbc 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -1993,7 +1993,7 @@ static const struct pci_epc_features tegra_pcie_epc_features = {
 	.msi_capable = true,
 	.bar[BAR_0] = { .type = BAR_FIXED, .fixed_size = SZ_1M,
 			.only_64bit = true, },
-	.bar[BAR_1] = { .type = BAR_RESERVED, },
+	.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
 	.bar[BAR_2] = { .type = BAR_RESERVED, },
 	.bar[BAR_3] = { .type = BAR_RESERVED, },
 	.bar[BAR_4] = { .type = BAR_RESERVED, },
diff --git a/drivers/pci/controller/dwc/pcie-uniphier-ep.c b/drivers/pci/controller/dwc/pcie-uniphier-ep.c
index d52753060970..f873a1659592 100644
--- a/drivers/pci/controller/dwc/pcie-uniphier-ep.c
+++ b/drivers/pci/controller/dwc/pcie-uniphier-ep.c
@@ -426,9 +426,9 @@ static const struct uniphier_pcie_ep_soc_data uniphier_pro5_data = {
 		.msix_capable = false,
 		.align = 1 << 16,
 		.bar[BAR_0] = { .only_64bit = true, },
-		.bar[BAR_1] = { .type = BAR_RESERVED, },
+		.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
 		.bar[BAR_2] = { .only_64bit = true, },
-		.bar[BAR_3] = { .type = BAR_RESERVED, },
+		.bar[BAR_3] = { .type = BAR_64BIT_UPPER, },
 		.bar[BAR_4] = { .type = BAR_RESERVED, },
 		.bar[BAR_5] = { .type = BAR_RESERVED, },
 	},
@@ -445,11 +445,11 @@ static const struct uniphier_pcie_ep_soc_data uniphier_nx1_data = {
 		.msix_capable = false,
 		.align = 1 << 12,
 		.bar[BAR_0] = { .only_64bit = true, },
-		.bar[BAR_1] = { .type = BAR_RESERVED, },
+		.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
 		.bar[BAR_2] = { .only_64bit = true, },
-		.bar[BAR_3] = { .type = BAR_RESERVED, },
+		.bar[BAR_3] = { .type = BAR_64BIT_UPPER, },
 		.bar[BAR_4] = { .only_64bit = true, },
-		.bar[BAR_5] = { .type = BAR_RESERVED, },
+		.bar[BAR_5] = { .type = BAR_64BIT_UPPER, },
 	},
 };
 
diff --git a/drivers/pci/controller/pcie-rcar-ep.c b/drivers/pci/controller/pcie-rcar-ep.c
index 657875ef4657..9b3f5391fabe 100644
--- a/drivers/pci/controller/pcie-rcar-ep.c
+++ b/drivers/pci/controller/pcie-rcar-ep.c
@@ -440,13 +440,13 @@ static const struct pci_epc_features rcar_pcie_epc_features = {
 	/* use 64-bit BARs so mark BAR[1,3,5] as reserved */
 	.bar[BAR_0] = { .type = BAR_FIXED, .fixed_size = 128,
 			.only_64bit = true, },
-	.bar[BAR_1] = { .type = BAR_RESERVED, },
+	.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
 	.bar[BAR_2] = { .type = BAR_FIXED, .fixed_size = 256,
 			.only_64bit = true, },
-	.bar[BAR_3] = { .type = BAR_RESERVED, },
+	.bar[BAR_3] = { .type = BAR_64BIT_UPPER, },
 	.bar[BAR_4] = { .type = BAR_FIXED, .fixed_size = 256,
 			.only_64bit = true, },
-	.bar[BAR_5] = { .type = BAR_RESERVED, },
+	.bar[BAR_5] = { .type = BAR_64BIT_UPPER, },
 };
 
 static const struct pci_epc_features*
diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index e546b3dbb240..1ad2f62963c8 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -104,7 +104,8 @@ enum pci_barno pci_epc_get_next_free_bar(const struct pci_epc_features
 
 	for (i = bar; i < PCI_STD_NUM_BARS; i++) {
 		/* If the BAR is not reserved, return it. */
-		if (epc_features->bar[i].type != BAR_RESERVED)
+		if (epc_features->bar[i].type != BAR_RESERVED &&
+		    epc_features->bar[i].type != BAR_64BIT_UPPER)
 			return i;
 	}
 
diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index c021c7af175f..c22f8a6cf9a3 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -192,12 +192,15 @@ struct pci_epc {
  *		   NOTE: An EPC driver can currently only set a single supported
  *		   size.
  * @BAR_RESERVED: The BAR should not be touched by an EPF driver.
+ * @BAR_64BIT_UPPER: Should only be set on a BAR if the preceding BAR is marked
+ *		     as only_64bit.
  */
 enum pci_epc_bar_type {
 	BAR_PROGRAMMABLE = 0,
 	BAR_FIXED,
 	BAR_RESIZABLE,
 	BAR_RESERVED,
+	BAR_64BIT_UPPER,
 };
 
 /**
@@ -207,7 +210,7 @@ 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. Additionally, the BAR succeeding
- *		this BAR must be set to type BAR_RESERVED.
+ *		this BAR must be set to type BAR_64BIT_UPPER.
  *
  *		only_64bit should not be set on a BAR of type BAR_RESERVED.
  *		(If BARx is a 64-bit BAR that an EPF driver is not allowed to
-- 
2.53.0

[PATCH v3 2/9] PCI: endpoint: Describe reserved subregions within BARs

[Niklas Cassel]

From: Koichiro Den <den@valinux.co.jp>

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.

Tested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Signed-off-by: Koichiro Den <den@valinux.co.jp>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Tested-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 include/linux/pci-epc.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index c22f8a6cf9a3..f7f48f43d370 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -203,6 +203,30 @@ enum pci_epc_bar_type {
 	BAR_64BIT_UPPER,
 };
 
+/**
+ * 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
@@ -216,11 +240,15 @@ enum pci_epc_bar_type {
  *		(If BARx is a 64-bit BAR that an EPF driver is not allowed to
  *		touch, then both BARx and BARx+1 must be set to type
  *		BAR_RESERVED.)
+ * @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;
 };
 
 /**
-- 
2.53.0

[PATCH v3 3/9] PCI: dw-rockchip: Describe RK3588 BAR4 DMA ctrl window

[Niklas Cassel]

From: Koichiro Den <den@valinux.co.jp>

On RK3588 PCIe3_4L in EP mode, the integrated DMA controller registers
are permanently mapped to BAR4 and must not be repurposed by EPF
drivers.

When the remote peer needs to access these registers, it must use the
fixed BAR4 window instead of creating another inbound mapping in a
different BAR. Mixing the fixed window with an additional mapping can
lead to incorrect behavior.

Advertise the DMA controller MMIO window as a reserved BAR subregion so
EPF drivers can reuse it safely.

Reviewed-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Signed-off-by: Koichiro Den <den@valinux.co.jp>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Tested-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/controller/dwc/pcie-dw-rockchip.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
index 5b17da63151d..ecc28093c589 100644
--- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
+++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
@@ -403,6 +403,15 @@ static const struct pci_epc_features rockchip_pcie_epc_features_rk3568 = {
 	.bar[BAR_5] = { .type = BAR_RESIZABLE, },
 };
 
+static const struct pci_epc_bar_rsvd_region rk3588_bar4_rsvd[] = {
+	{
+		/* DMA_CAP (BAR4: DMA Port Logic Structure) */
+		.type = PCI_EPC_BAR_RSVD_DMA_CTRL_MMIO,
+		.offset = 0x0,
+		.size = 0x2000,
+	},
+};
+
 /*
  * BAR4 on rk3588 exposes the ATU Port Logic Structure to the host regardless of
  * iATU settings for BAR4. This means that BAR4 cannot be used by an EPF driver,
@@ -420,7 +429,11 @@ static const struct pci_epc_features rockchip_pcie_epc_features_rk3588 = {
 	.bar[BAR_1] = { .type = BAR_RESIZABLE, },
 	.bar[BAR_2] = { .type = BAR_RESIZABLE, },
 	.bar[BAR_3] = { .type = BAR_RESIZABLE, },
-	.bar[BAR_4] = { .type = BAR_RESERVED, },
+	.bar[BAR_4] = {
+		.type = BAR_RESERVED,
+		.nr_rsvd_regions = ARRAY_SIZE(rk3588_bar4_rsvd),
+		.rsvd_regions = rk3588_bar4_rsvd,
+	},
 	.bar[BAR_5] = { .type = BAR_RESIZABLE, },
 };
 
-- 
2.53.0

[PATCH v3 4/9] PCI: endpoint: Introduce pci_epc_bar_type BAR_DISABLED

[Niklas Cassel]

Add a pci_epc_bar_type BAR_DISABLED to more clearly differentiate from
BAR_RESERVED.

This BAR type will only be used to describe a BAR that the EPC driver
should disable, and will thus never be available to an EPF drive.
(Unlike BAR_RESERVED, which will never be disabled by default by an EPC
driver.)

Tested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Co-developed-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Tested-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/endpoint/pci-epc-core.c |  5 +++--
 include/linux/pci-epc.h             | 12 ++++++++++--
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index 1ad2f62963c8..32cf9a9bc365 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -103,9 +103,10 @@ enum pci_barno pci_epc_get_next_free_bar(const struct pci_epc_features
 		bar++;
 
 	for (i = bar; i < PCI_STD_NUM_BARS; i++) {
-		/* If the BAR is not reserved, return it. */
+		/* If the BAR is not reserved or disabled, return it. */
 		if (epc_features->bar[i].type != BAR_RESERVED &&
-		    epc_features->bar[i].type != BAR_64BIT_UPPER)
+		    epc_features->bar[i].type != BAR_64BIT_UPPER &&
+		    epc_features->bar[i].type != BAR_DISABLED)
 			return i;
 	}
 
diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index f7f48f43d370..63a24ebf144c 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -191,7 +191,14 @@ struct pci_epc {
  * @BAR_RESIZABLE: The BAR implements the PCI-SIG Resizable BAR Capability.
  *		   NOTE: An EPC driver can currently only set a single supported
  *		   size.
- * @BAR_RESERVED: The BAR should not be touched by an EPF driver.
+ * @BAR_RESERVED: Used for HW-backed BARs (e.g. MSI-X table, DMA regs). The BAR
+ *		  should not be disabled by an EPC driver. The BAR should not be
+ *		  reprogrammed by an EPF driver. An EPF driver is allowed to
+ *		  disable the BAR if absolutely necessary. (However, right now
+ *		  there is no EPC operation to disable a BAR that has not been
+ *		  programmed using pci_epc_set_bar().)
+ * @BAR_DISABLED: The BAR should be disabled by an EPC driver. The BAR will be
+ *		  unavailable to an EPF driver.
  * @BAR_64BIT_UPPER: Should only be set on a BAR if the preceding BAR is marked
  *		     as only_64bit.
  */
@@ -200,6 +207,7 @@ enum pci_epc_bar_type {
 	BAR_FIXED,
 	BAR_RESIZABLE,
 	BAR_RESERVED,
+	BAR_DISABLED,
 	BAR_64BIT_UPPER,
 };
 
@@ -238,7 +246,7 @@ struct pci_epc_bar_rsvd_region {
  *
  *		only_64bit should not be set on a BAR of type BAR_RESERVED.
  *		(If BARx is a 64-bit BAR that an EPF driver is not allowed to
- *		touch, then both BARx and BARx+1 must be set to type
+ *		reprogram, then both BARx and BARx+1 must be set to type
  *		BAR_RESERVED.)
  * @nr_rsvd_regions: number of fixed subregions described for BAR_RESERVED
  * @rsvd_regions: fixed subregions behind BAR_RESERVED
-- 
2.53.0

[PATCH v3 5/9] PCI: dwc: Replace certain BAR_RESERVED with BAR_DISABLED in glue drivers

[Niklas Cassel]

Most DWC based EPC glue drivers that have BARs marked as BAR_RESERVED in
epc_features also call dw_pcie_ep_reset_bar() for these reserved BARs in
ep->ops->init(). (The only exception is pci-keystone.c.)

An EPF driver will be able to get/enable BARs that have been disabled/reset
using dw_pcie_ep_reset_bar(), except if the BAR is marked as BAR_RESERVED
(see pci_epc_get_next_free_bar()).

Thus, all EPC drivers that have BARs marked as BAR_RESERVED in epc_features
and call dw_pcie_ep_reset_bar(), should really have these BARs marked as
BAR_DISABLED. If dw_pcie_ep_reset_bar() is not called by the glue driver,
the BARs are kept as BAR_RESERVED.

No EPC drivers outside drivers/pci/controllers/dwc mark their BARs as
BAR_RESERVED, so there is nothing to do in non-DWC based EPC drivers.

Tested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Tested-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/controller/dwc/pci-imx6.c         | 12 ++++++------
 drivers/pci/controller/dwc/pci-keystone.c     | 12 ++++++++++++
 drivers/pci/controller/dwc/pcie-rcar-gen4.c   |  6 +++---
 drivers/pci/controller/dwc/pcie-tegra194.c    |  8 ++++----
 drivers/pci/controller/dwc/pcie-uniphier-ep.c |  4 ++--
 5 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index a5b8d0b71677..ec1e3557ca53 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -1433,19 +1433,19 @@ static int imx_pcie_ep_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
 static const struct pci_epc_features imx8m_pcie_epc_features = {
 	DWC_EPC_COMMON_FEATURES,
 	.msi_capable = true,
-	.bar[BAR_1] = { .type = BAR_RESERVED, },
-	.bar[BAR_3] = { .type = BAR_RESERVED, },
+	.bar[BAR_1] = { .type = BAR_DISABLED, },
+	.bar[BAR_3] = { .type = BAR_DISABLED, },
 	.bar[BAR_4] = { .type = BAR_FIXED, .fixed_size = SZ_256, },
-	.bar[BAR_5] = { .type = BAR_RESERVED, },
+	.bar[BAR_5] = { .type = BAR_DISABLED, },
 	.align = SZ_64K,
 };
 
 static const struct pci_epc_features imx8q_pcie_epc_features = {
 	DWC_EPC_COMMON_FEATURES,
 	.msi_capable = true,
-	.bar[BAR_1] = { .type = BAR_RESERVED, },
-	.bar[BAR_3] = { .type = BAR_RESERVED, },
-	.bar[BAR_5] = { .type = BAR_RESERVED, },
+	.bar[BAR_1] = { .type = BAR_DISABLED, },
+	.bar[BAR_3] = { .type = BAR_DISABLED, },
+	.bar[BAR_5] = { .type = BAR_DISABLED, },
 	.align = SZ_64K,
 };
 
diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
index 20fa4dadb82a..278d2dba1db0 100644
--- a/drivers/pci/controller/dwc/pci-keystone.c
+++ b/drivers/pci/controller/dwc/pci-keystone.c
@@ -933,6 +933,18 @@ static const struct pci_epc_features ks_pcie_am654_epc_features = {
 	DWC_EPC_COMMON_FEATURES,
 	.msi_capable = true,
 	.msix_capable = true,
+	/*
+	 * TODO: This driver is the only DWC glue driver that had BAR_RESERVED
+	 * BARs, but did not call dw_pcie_ep_reset_bar() for the reserved BARs.
+	 *
+	 * To not change the existing behavior, these BARs were not migrated to
+	 * BAR_DISABLED. If this driver wants the BAR_RESERVED BARs to be
+	 * disabled, it should migrate them to BAR_DISABLED.
+	 *
+	 * If they actually should be enabled, then the driver must also define
+	 * what is behind these reserved BARs, see the definition of struct
+	 * pci_epc_bar_rsvd_region.
+	 */
 	.bar[BAR_0] = { .type = BAR_RESERVED, },
 	.bar[BAR_1] = { .type = BAR_RESERVED, },
 	.bar[BAR_2] = { .type = BAR_RESIZABLE, },
diff --git a/drivers/pci/controller/dwc/pcie-rcar-gen4.c b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
index a6912e85e4dd..9dd05bac22b9 100644
--- a/drivers/pci/controller/dwc/pcie-rcar-gen4.c
+++ b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
@@ -422,10 +422,10 @@ static int rcar_gen4_pcie_ep_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
 static const struct pci_epc_features rcar_gen4_pcie_epc_features = {
 	DWC_EPC_COMMON_FEATURES,
 	.msi_capable = true,
-	.bar[BAR_1] = { .type = BAR_RESERVED, },
-	.bar[BAR_3] = { .type = BAR_RESERVED, },
+	.bar[BAR_1] = { .type = BAR_DISABLED, },
+	.bar[BAR_3] = { .type = BAR_DISABLED, },
 	.bar[BAR_4] = { .type = BAR_FIXED, .fixed_size = 256 },
-	.bar[BAR_5] = { .type = BAR_RESERVED, },
+	.bar[BAR_5] = { .type = BAR_DISABLED, },
 	.align = SZ_1M,
 };
 
diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 31aa9a494dbc..9f9453e8cd23 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -1994,10 +1994,10 @@ static const struct pci_epc_features tegra_pcie_epc_features = {
 	.bar[BAR_0] = { .type = BAR_FIXED, .fixed_size = SZ_1M,
 			.only_64bit = true, },
 	.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
-	.bar[BAR_2] = { .type = BAR_RESERVED, },
-	.bar[BAR_3] = { .type = BAR_RESERVED, },
-	.bar[BAR_4] = { .type = BAR_RESERVED, },
-	.bar[BAR_5] = { .type = BAR_RESERVED, },
+	.bar[BAR_2] = { .type = BAR_DISABLED, },
+	.bar[BAR_3] = { .type = BAR_DISABLED, },
+	.bar[BAR_4] = { .type = BAR_DISABLED, },
+	.bar[BAR_5] = { .type = BAR_DISABLED, },
 	.align = SZ_64K,
 };
 
diff --git a/drivers/pci/controller/dwc/pcie-uniphier-ep.c b/drivers/pci/controller/dwc/pcie-uniphier-ep.c
index f873a1659592..5bde3ee682b5 100644
--- a/drivers/pci/controller/dwc/pcie-uniphier-ep.c
+++ b/drivers/pci/controller/dwc/pcie-uniphier-ep.c
@@ -429,8 +429,8 @@ static const struct uniphier_pcie_ep_soc_data uniphier_pro5_data = {
 		.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
 		.bar[BAR_2] = { .only_64bit = true, },
 		.bar[BAR_3] = { .type = BAR_64BIT_UPPER, },
-		.bar[BAR_4] = { .type = BAR_RESERVED, },
-		.bar[BAR_5] = { .type = BAR_RESERVED, },
+		.bar[BAR_4] = { .type = BAR_DISABLED, },
+		.bar[BAR_5] = { .type = BAR_DISABLED, },
 	},
 };
 
-- 
2.53.0

[PATCH v3 6/9] PCI: dwc: Disable BARs in common code instead of in each glue driver

[Niklas Cassel]

The current EPC core design relies on an EPC driver disabling all BARs by
default. An EPF driver will then enable the BARs that it wants to enabled.

This design is there because there is no epc->ops->disable_bar().
(There is a epc->ops->clear_bar(), but that is only to disable a BAR that
has been enabled using epc->ops->set_bar() first.)

By default, an EPF driver will not be able to get/enable BARs that are
marked as BAR_RESERVED or BAR_DISABLED (see pci_epc_get_next_free_bar()).

Since the current EPC code design requires an EPC driver to disable all
BARs by default, let's move this to DWC common code from each glue driver.

BAR_RESERVED BARs are not disabled by default because these BARs are
hardware backed, and should only be disabled explicitly by an EPF driver
if absolutely necessary for the EPF driver to function correctly.
(This is similar to how e.g. NVMe may have vendor specific BARs outside of
the mandatory BAR0 which contains the NVMe registers.)

Note that there is currently no EPC operation to disable a BAR that has not
first been programmed using pci_epc_set_bar(). If an EPF driver ever wants
to disable a BAR marked as BAR_RESERVED, a disable_bar() operation would
have to be added first.

No functional changes intended.

Tested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Tested-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/controller/dwc/pci-dra7xx.c       |  4 ----
 drivers/pci/controller/dwc/pci-imx6.c         | 10 --------
 .../pci/controller/dwc/pci-layerscape-ep.c    |  4 ----
 drivers/pci/controller/dwc/pcie-artpec6.c     |  4 ----
 .../pci/controller/dwc/pcie-designware-ep.c   | 24 +++++++++++++++++++
 .../pci/controller/dwc/pcie-designware-plat.c | 10 --------
 drivers/pci/controller/dwc/pcie-dw-rockchip.c |  8 +------
 drivers/pci/controller/dwc/pcie-qcom-ep.c     | 10 --------
 drivers/pci/controller/dwc/pcie-rcar-gen4.c   | 10 --------
 drivers/pci/controller/dwc/pcie-stm32-ep.c    | 10 --------
 drivers/pci/controller/dwc/pcie-tegra194.c    | 10 --------
 drivers/pci/controller/dwc/pcie-uniphier-ep.c | 10 --------
 12 files changed, 25 insertions(+), 89 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-dra7xx.c b/drivers/pci/controller/dwc/pci-dra7xx.c
index d5d26229063f..cd904659c321 100644
--- a/drivers/pci/controller/dwc/pci-dra7xx.c
+++ b/drivers/pci/controller/dwc/pci-dra7xx.c
@@ -378,10 +378,6 @@ static void dra7xx_pcie_ep_init(struct dw_pcie_ep *ep)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
 	struct dra7xx_pcie *dra7xx = to_dra7xx_pcie(pci);
-	enum pci_barno bar;
-
-	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
-		dw_pcie_ep_reset_bar(pci, bar);
 
 	dra7xx_pcie_enable_wrapper_interrupts(dra7xx);
 }
diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index ec1e3557ca53..f5fe5cfc46c7 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -1401,15 +1401,6 @@ static const struct dw_pcie_ops dw_pcie_ops = {
 	.stop_link = imx_pcie_stop_link,
 };
 
-static void imx_pcie_ep_init(struct dw_pcie_ep *ep)
-{
-	enum pci_barno bar;
-	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
-
-	for (bar = BAR_0; bar <= BAR_5; bar++)
-		dw_pcie_ep_reset_bar(pci, bar);
-}
-
 static int imx_pcie_ep_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
 				  unsigned int type, u16 interrupt_num)
 {
@@ -1478,7 +1469,6 @@ imx_pcie_ep_get_features(struct dw_pcie_ep *ep)
 }
 
 static const struct dw_pcie_ep_ops pcie_ep_ops = {
-	.init = imx_pcie_ep_init,
 	.raise_irq = imx_pcie_ep_raise_irq,
 	.get_features = imx_pcie_ep_get_features,
 };
diff --git a/drivers/pci/controller/dwc/pci-layerscape-ep.c b/drivers/pci/controller/dwc/pci-layerscape-ep.c
index 5a03a8f895f9..1f5fccdb4ff4 100644
--- a/drivers/pci/controller/dwc/pci-layerscape-ep.c
+++ b/drivers/pci/controller/dwc/pci-layerscape-ep.c
@@ -152,15 +152,11 @@ static void ls_pcie_ep_init(struct dw_pcie_ep *ep)
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
 	struct ls_pcie_ep *pcie = to_ls_pcie_ep(pci);
 	struct dw_pcie_ep_func *ep_func;
-	enum pci_barno bar;
 
 	ep_func = dw_pcie_ep_get_func_from_ep(ep, 0);
 	if (!ep_func)
 		return;
 
-	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
-		dw_pcie_ep_reset_bar(pci, bar);
-
 	pcie->ls_epc->msi_capable = ep_func->msi_cap ? true : false;
 	pcie->ls_epc->msix_capable = ep_func->msix_cap ? true : false;
 }
diff --git a/drivers/pci/controller/dwc/pcie-artpec6.c b/drivers/pci/controller/dwc/pcie-artpec6.c
index e994b75986c3..55cb957ae1f3 100644
--- a/drivers/pci/controller/dwc/pcie-artpec6.c
+++ b/drivers/pci/controller/dwc/pcie-artpec6.c
@@ -340,15 +340,11 @@ static void artpec6_pcie_ep_init(struct dw_pcie_ep *ep)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
 	struct artpec6_pcie *artpec6_pcie = to_artpec6_pcie(pci);
-	enum pci_barno bar;
 
 	artpec6_pcie_assert_core_reset(artpec6_pcie);
 	artpec6_pcie_init_phy(artpec6_pcie);
 	artpec6_pcie_deassert_core_reset(artpec6_pcie);
 	artpec6_pcie_wait_for_phy(artpec6_pcie);
-
-	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
-		dw_pcie_ep_reset_bar(pci, bar);
 }
 
 static int artpec6_pcie_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 295076cf70de..386bfb7b2bf6 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -1114,6 +1114,28 @@ static void dw_pcie_ep_init_non_sticky_registers(struct dw_pcie *pci)
 	dw_pcie_dbi_ro_wr_dis(pci);
 }
 
+static void dw_pcie_ep_disable_bars(struct dw_pcie_ep *ep)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+	enum pci_epc_bar_type bar_type;
+	enum pci_barno bar;
+
+	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
+		bar_type = dw_pcie_ep_get_bar_type(ep, bar);
+
+		/*
+		 * Reserved BARs should not get disabled by default. All other
+		 * BAR types are disabled by default.
+		 *
+		 * This is in line with the current EPC core design, where all
+		 * BARs are disabled by default, and then the EPF driver enables
+		 * the BARs it wishes to use.
+		 */
+		if (bar_type != BAR_RESERVED)
+			dw_pcie_ep_reset_bar(pci, bar);
+	}
+}
+
 /**
  * dw_pcie_ep_init_registers - Initialize DWC EP specific registers
  * @ep: DWC EP device
@@ -1196,6 +1218,8 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep)
 	if (ep->ops->init)
 		ep->ops->init(ep);
 
+	dw_pcie_ep_disable_bars(ep);
+
 	/*
 	 * PCIe r6.0, section 7.9.15 states that for endpoints that support
 	 * PTM, this capability structure is required in exactly one
diff --git a/drivers/pci/controller/dwc/pcie-designware-plat.c b/drivers/pci/controller/dwc/pcie-designware-plat.c
index 8530746ec5cb..d103ab759c4e 100644
--- a/drivers/pci/controller/dwc/pcie-designware-plat.c
+++ b/drivers/pci/controller/dwc/pcie-designware-plat.c
@@ -32,15 +32,6 @@ struct dw_plat_pcie_of_data {
 static const struct dw_pcie_host_ops dw_plat_pcie_host_ops = {
 };
 
-static void dw_plat_pcie_ep_init(struct dw_pcie_ep *ep)
-{
-	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
-	enum pci_barno bar;
-
-	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
-		dw_pcie_ep_reset_bar(pci, bar);
-}
-
 static int dw_plat_pcie_ep_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
 				     unsigned int type, u16 interrupt_num)
 {
@@ -73,7 +64,6 @@ dw_plat_pcie_get_features(struct dw_pcie_ep *ep)
 }
 
 static const struct dw_pcie_ep_ops pcie_ep_ops = {
-	.init = dw_plat_pcie_ep_init,
 	.raise_irq = dw_plat_pcie_ep_raise_irq,
 	.get_features = dw_plat_pcie_get_features,
 };
diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
index ecc28093c589..8db27199cfa6 100644
--- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
+++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
@@ -361,13 +361,9 @@ static void rockchip_pcie_ep_hide_broken_ats_cap_rk3588(struct dw_pcie_ep *ep)
 static void rockchip_pcie_ep_init(struct dw_pcie_ep *ep)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
-	enum pci_barno bar;
 
 	rockchip_pcie_enable_l0s(pci);
 	rockchip_pcie_ep_hide_broken_ats_cap_rk3588(ep);
-
-	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
-		dw_pcie_ep_reset_bar(pci, bar);
 };
 
 static int rockchip_pcie_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
@@ -415,9 +411,7 @@ static const struct pci_epc_bar_rsvd_region rk3588_bar4_rsvd[] = {
 /*
  * BAR4 on rk3588 exposes the ATU Port Logic Structure to the host regardless of
  * iATU settings for BAR4. This means that BAR4 cannot be used by an EPF driver,
- * so mark it as RESERVED. (rockchip_pcie_ep_init() will disable all BARs by
- * default.) If the host could write to BAR4, the iATU settings (for all other
- * BARs) would be overwritten, resulting in (all other BARs) no longer working.
+ * so mark it as RESERVED.
  */
 static const struct pci_epc_features rockchip_pcie_epc_features_rk3588 = {
 	DWC_EPC_COMMON_FEATURES,
diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index e55675b3840a..e8c8ba1659fd 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -861,17 +861,7 @@ qcom_pcie_epc_get_features(struct dw_pcie_ep *pci_ep)
 	return &qcom_pcie_epc_features;
 }
 
-static void qcom_pcie_ep_init(struct dw_pcie_ep *ep)
-{
-	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
-	enum pci_barno bar;
-
-	for (bar = BAR_0; bar <= BAR_5; bar++)
-		dw_pcie_ep_reset_bar(pci, bar);
-}
-
 static const struct dw_pcie_ep_ops pci_ep_ops = {
-	.init = qcom_pcie_ep_init,
 	.raise_irq = qcom_pcie_ep_raise_irq,
 	.get_features = qcom_pcie_epc_get_features,
 };
diff --git a/drivers/pci/controller/dwc/pcie-rcar-gen4.c b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
index 9dd05bac22b9..1198ddc1752c 100644
--- a/drivers/pci/controller/dwc/pcie-rcar-gen4.c
+++ b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
@@ -386,15 +386,6 @@ static void rcar_gen4_pcie_ep_pre_init(struct dw_pcie_ep *ep)
 	writel(PCIEDMAINTSTSEN_INIT, rcar->base + PCIEDMAINTSTSEN);
 }
 
-static void rcar_gen4_pcie_ep_init(struct dw_pcie_ep *ep)
-{
-	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
-	enum pci_barno bar;
-
-	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
-		dw_pcie_ep_reset_bar(pci, bar);
-}
-
 static void rcar_gen4_pcie_ep_deinit(struct rcar_gen4_pcie *rcar)
 {
 	writel(0, rcar->base + PCIEDMAINTSTSEN);
@@ -449,7 +440,6 @@ static unsigned int rcar_gen4_pcie_ep_get_dbi2_offset(struct dw_pcie_ep *ep,
 
 static const struct dw_pcie_ep_ops pcie_ep_ops = {
 	.pre_init = rcar_gen4_pcie_ep_pre_init,
-	.init = rcar_gen4_pcie_ep_init,
 	.raise_irq = rcar_gen4_pcie_ep_raise_irq,
 	.get_features = rcar_gen4_pcie_ep_get_features,
 	.get_dbi_offset = rcar_gen4_pcie_ep_get_dbi_offset,
diff --git a/drivers/pci/controller/dwc/pcie-stm32-ep.c b/drivers/pci/controller/dwc/pcie-stm32-ep.c
index c1944b40ce02..a7988dff1045 100644
--- a/drivers/pci/controller/dwc/pcie-stm32-ep.c
+++ b/drivers/pci/controller/dwc/pcie-stm32-ep.c
@@ -28,15 +28,6 @@ struct stm32_pcie {
 	unsigned int perst_irq;
 };
 
-static void stm32_pcie_ep_init(struct dw_pcie_ep *ep)
-{
-	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
-	enum pci_barno bar;
-
-	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
-		dw_pcie_ep_reset_bar(pci, bar);
-}
-
 static int stm32_pcie_start_link(struct dw_pcie *pci)
 {
 	struct stm32_pcie *stm32_pcie = to_stm32_pcie(pci);
@@ -82,7 +73,6 @@ stm32_pcie_get_features(struct dw_pcie_ep *ep)
 }
 
 static const struct dw_pcie_ep_ops stm32_pcie_ep_ops = {
-	.init = stm32_pcie_ep_init,
 	.raise_irq = stm32_pcie_raise_irq,
 	.get_features = stm32_pcie_get_features,
 };
diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 9f9453e8cd23..3a6bffaff9ea 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -1923,15 +1923,6 @@ static irqreturn_t tegra_pcie_ep_pex_rst_irq(int irq, void *arg)
 	return IRQ_HANDLED;
 }
 
-static void tegra_pcie_ep_init(struct dw_pcie_ep *ep)
-{
-	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
-	enum pci_barno bar;
-
-	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
-		dw_pcie_ep_reset_bar(pci, bar);
-};
-
 static int tegra_pcie_ep_raise_intx_irq(struct tegra_pcie_dw *pcie, u16 irq)
 {
 	/* Tegra194 supports only INTA */
@@ -2008,7 +1999,6 @@ tegra_pcie_ep_get_features(struct dw_pcie_ep *ep)
 }
 
 static const struct dw_pcie_ep_ops pcie_ep_ops = {
-	.init = tegra_pcie_ep_init,
 	.raise_irq = tegra_pcie_ep_raise_irq,
 	.get_features = tegra_pcie_ep_get_features,
 };
diff --git a/drivers/pci/controller/dwc/pcie-uniphier-ep.c b/drivers/pci/controller/dwc/pcie-uniphier-ep.c
index 5bde3ee682b5..494376d1812d 100644
--- a/drivers/pci/controller/dwc/pcie-uniphier-ep.c
+++ b/drivers/pci/controller/dwc/pcie-uniphier-ep.c
@@ -203,15 +203,6 @@ static void uniphier_pcie_stop_link(struct dw_pcie *pci)
 	uniphier_pcie_ltssm_enable(priv, false);
 }
 
-static void uniphier_pcie_ep_init(struct dw_pcie_ep *ep)
-{
-	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
-	enum pci_barno bar;
-
-	for (bar = BAR_0; bar <= BAR_5; bar++)
-		dw_pcie_ep_reset_bar(pci, bar);
-}
-
 static int uniphier_pcie_ep_raise_intx_irq(struct dw_pcie_ep *ep)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
@@ -283,7 +274,6 @@ uniphier_pcie_get_features(struct dw_pcie_ep *ep)
 }
 
 static const struct dw_pcie_ep_ops uniphier_pcie_ep_ops = {
-	.init = uniphier_pcie_ep_init,
 	.raise_irq = uniphier_pcie_ep_raise_irq,
 	.get_features = uniphier_pcie_get_features,
 };
-- 
2.53.0

[PATCH v3 7/9] PCI: endpoint: pci-epf-test: Advertise reserved BARs

[Niklas Cassel]

Advertise reserved BARs as reserved in the Capabilities register,
such that the host side driver will be able to skip reserved BARs.

Tested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Tested-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/endpoint/functions/pci-epf-test.c | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index 6030ae1373b1..14e61ebe1f11 100644
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -65,6 +65,12 @@
 #define CAP_INTX			BIT(3)
 #define CAP_SUBRANGE_MAPPING		BIT(4)
 #define CAP_DYNAMIC_INBOUND_MAPPING	BIT(5)
+#define CAP_BAR0_RESERVED		BIT(6)
+#define CAP_BAR1_RESERVED		BIT(7)
+#define CAP_BAR2_RESERVED		BIT(8)
+#define CAP_BAR3_RESERVED		BIT(9)
+#define CAP_BAR4_RESERVED		BIT(10)
+#define CAP_BAR5_RESERVED		BIT(11)
 
 #define PCI_EPF_TEST_BAR_SUBRANGE_NSUB	2
 
@@ -1112,6 +1118,24 @@ static void pci_epf_test_set_capabilities(struct pci_epf *epf)
 	    epf_test->epc_features->subrange_mapping)
 		caps |= CAP_SUBRANGE_MAPPING;
 
+	if (epf_test->epc_features->bar[BAR_0].type == BAR_RESERVED)
+		caps |= CAP_BAR0_RESERVED;
+
+	if (epf_test->epc_features->bar[BAR_1].type == BAR_RESERVED)
+		caps |= CAP_BAR1_RESERVED;
+
+	if (epf_test->epc_features->bar[BAR_2].type == BAR_RESERVED)
+		caps |= CAP_BAR2_RESERVED;
+
+	if (epf_test->epc_features->bar[BAR_3].type == BAR_RESERVED)
+		caps |= CAP_BAR3_RESERVED;
+
+	if (epf_test->epc_features->bar[BAR_4].type == BAR_RESERVED)
+		caps |= CAP_BAR4_RESERVED;
+
+	if (epf_test->epc_features->bar[BAR_5].type == BAR_RESERVED)
+		caps |= CAP_BAR5_RESERVED;
+
 	reg->caps = cpu_to_le32(caps);
 }
 
-- 
2.53.0

[PATCH v3 8/9] misc: pci_endpoint_test: Give reserved BARs a distinct error code

[Niklas Cassel]

Give reserved BARs a distinct error code, such that the pci_endpoint_test
selftest will be able to skip test cases that are run against reserved
BARs.

Tested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Tested-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/misc/pci_endpoint_test.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
index 93cd57d20881..89d0aba059da 100644
--- a/drivers/misc/pci_endpoint_test.c
+++ b/drivers/misc/pci_endpoint_test.c
@@ -85,6 +85,12 @@
 #define CAP_INTX				BIT(3)
 #define CAP_SUBRANGE_MAPPING			BIT(4)
 #define CAP_DYNAMIC_INBOUND_MAPPING		BIT(5)
+#define CAP_BAR0_RESERVED			BIT(6)
+#define CAP_BAR1_RESERVED			BIT(7)
+#define CAP_BAR2_RESERVED			BIT(8)
+#define CAP_BAR3_RESERVED			BIT(9)
+#define CAP_BAR4_RESERVED			BIT(10)
+#define CAP_BAR5_RESERVED			BIT(11)
 
 #define PCI_ENDPOINT_TEST_DB_BAR		0x34
 #define PCI_ENDPOINT_TEST_DB_OFFSET		0x38
@@ -109,6 +115,7 @@
 #define PCI_DEVICE_ID_ROCKCHIP_RK3588		0x3588
 
 #define PCI_ENDPOINT_TEST_BAR_SUBRANGE_NSUB	2
+#define PCI_ENDPOINT_CAP_BAR0_RESERVED_BIT	6
 
 static DEFINE_IDA(pci_endpoint_test_ida);
 
@@ -276,6 +283,11 @@ static int pci_endpoint_test_request_irq(struct pci_endpoint_test *test)
 	return ret;
 }
 
+static bool bar_is_reserved(struct pci_endpoint_test *test, enum pci_barno bar)
+{
+	return test->ep_caps & BIT(bar + PCI_ENDPOINT_CAP_BAR0_RESERVED_BIT);
+}
+
 static const u32 bar_test_pattern[] = {
 	0xA0A0A0A0,
 	0xA1A1A1A1,
@@ -404,7 +416,7 @@ static int pci_endpoint_test_bars(struct pci_endpoint_test *test)
 
 	/* Write all BARs in order (without reading). */
 	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
-		if (test->bar[bar])
+		if (test->bar[bar] && !bar_is_reserved(test, bar))
 			pci_endpoint_test_bars_write_bar(test, bar);
 
 	/*
@@ -414,7 +426,7 @@ static int pci_endpoint_test_bars(struct pci_endpoint_test *test)
 	 * (Reading back the BAR directly after writing can not detect this.)
 	 */
 	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
-		if (test->bar[bar]) {
+		if (test->bar[bar] && !bar_is_reserved(test, bar)) {
 			ret = pci_endpoint_test_bars_read_bar(test, bar);
 			if (ret)
 				return ret;
@@ -1143,6 +1155,11 @@ static long pci_endpoint_test_ioctl(struct file *file, unsigned int cmd,
 		if (is_am654_pci_dev(pdev) && bar == BAR_0)
 			goto ret;
 
+		if (bar_is_reserved(test, bar)) {
+			ret = -ENOBUFS;
+			goto ret;
+		}
+
 		if (cmd == PCITEST_BAR)
 			ret = pci_endpoint_test_bar(test, bar);
 		else
-- 
2.53.0

[PATCH v3 9/9] selftests: pci_endpoint: Skip reserved BARs

[Niklas Cassel]

Running a test against a reserved BAR will result in the pci-epf-test
driver returning -ENOBUFS.

Make sure that the pci_endpoint_test selftest will return skip instead of
failure or success for reserved BARs.

Tested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Tested-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 tools/testing/selftests/pci_endpoint/pci_endpoint_test.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/pci_endpoint/pci_endpoint_test.c b/tools/testing/selftests/pci_endpoint/pci_endpoint_test.c
index e0dbbb2af8c7..c417fb3a198b 100644
--- a/tools/testing/selftests/pci_endpoint/pci_endpoint_test.c
+++ b/tools/testing/selftests/pci_endpoint/pci_endpoint_test.c
@@ -67,6 +67,8 @@ TEST_F(pci_ep_bar, BAR_TEST)
 	pci_ep_ioctl(PCITEST_BAR, variant->barno);
 	if (ret == -ENODATA)
 		SKIP(return, "BAR is disabled");
+	if (ret == -ENOBUFS)
+		SKIP(return, "BAR is reserved");
 	EXPECT_FALSE(ret) TH_LOG("Test failed for BAR%d", variant->barno);
 }
 
@@ -84,6 +86,8 @@ TEST_F(pci_ep_bar, BAR_SUBRANGE_TEST)
 		SKIP(return, "BAR is test register space");
 	if (ret == -EOPNOTSUPP)
 		SKIP(return, "Subrange map is not supported");
+	if (ret == -ENOBUFS)
+		SKIP(return, "BAR is reserved");
 	EXPECT_FALSE(ret) TH_LOG("Test failed for BAR%d", variant->barno);
 }
 
-- 
2.53.0

Re: [PATCH v3 0/9] PCI: endpoint: Differentiate between disabled and reserved BARs

[Niklas Cassel]

Hello Mani,

Gentle ping on this series.

Considering that there are two other series:
https://lore.kernel.org/linux-pci/20260302071427.534158-1-den@valinux.co.jp/
https://lore.kernel.org/linux-pci/20260303072004.2384079-1-mmaddireddy@nvidia.com/

that have this series as a dependency, I think it would be nice if we
could handle this series, so that the other two series are unblocked.


Kind regards,
Niklas

Re: [PATCH v3 1/9] PCI: endpoint: Introduce pci_epc_bar_type BAR_64BIT_UPPER

[Manivannan Sadhasivam]

On Mon, Mar 02, 2026 at 10:59:13AM +0100, Niklas Cassel wrote:
> Add a pci_epc_bar_type BAR_64BIT_UPPER to more clearly differentiate from
> BAR_RESERVED.
> 
> This BAR type will only be used for a BAR following a "only_64bit" BAR.
> 
> This makes the BAR description more clear, and the reader does no longer
> need to check the BAR type for the preceding BAR to know how to interpret
> the BAR type.
> 

I find the naming a bit confusing. How about BAR_64BIT_UPPER_BASE? This also
brings the question, do we really need to mark the preceding BAR? Why can't we
let the PCI EPC core to always assume that if the previous BAR has 'only_64bit'
bit set, next BAR cannot be used as a standalone 32bit BAR?

I find it weird or redundant to mark both BARs.

- Mani

> No functional changes.
> 
> Tested-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> Tested-by: Koichiro Den <den@valinux.co.jp>
> Signed-off-by: Niklas Cassel <cassel@kernel.org>
> ---
>  drivers/pci/controller/dwc/pci-layerscape-ep.c |  4 ++--
>  drivers/pci/controller/dwc/pcie-keembay.c      |  6 +++---
>  drivers/pci/controller/dwc/pcie-qcom-ep.c      |  4 ++--
>  drivers/pci/controller/dwc/pcie-tegra194.c     |  2 +-
>  drivers/pci/controller/dwc/pcie-uniphier-ep.c  | 10 +++++-----
>  drivers/pci/controller/pcie-rcar-ep.c          |  6 +++---
>  drivers/pci/endpoint/pci-epc-core.c            |  3 ++-
>  include/linux/pci-epc.h                        |  5 ++++-
>  8 files changed, 22 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-layerscape-ep.c b/drivers/pci/controller/dwc/pci-layerscape-ep.c
> index a4a800699f89..5a03a8f895f9 100644
> --- a/drivers/pci/controller/dwc/pci-layerscape-ep.c
> +++ b/drivers/pci/controller/dwc/pci-layerscape-ep.c
> @@ -251,9 +251,9 @@ static int __init ls_pcie_ep_probe(struct platform_device *pdev)
>  	pci->ops = pcie->drvdata->dw_pcie_ops;
>  
>  	ls_epc->bar[BAR_2].only_64bit = true;
> -	ls_epc->bar[BAR_3].type = BAR_RESERVED;
> +	ls_epc->bar[BAR_3].type = BAR_64BIT_UPPER;
>  	ls_epc->bar[BAR_4].only_64bit = true;
> -	ls_epc->bar[BAR_5].type = BAR_RESERVED;
> +	ls_epc->bar[BAR_5].type = BAR_64BIT_UPPER;
>  	ls_epc->linkup_notifier = true;
>  
>  	pcie->pci = pci;
> diff --git a/drivers/pci/controller/dwc/pcie-keembay.c b/drivers/pci/controller/dwc/pcie-keembay.c
> index 2666a9c3d67e..5a00b8cf5b53 100644
> --- a/drivers/pci/controller/dwc/pcie-keembay.c
> +++ b/drivers/pci/controller/dwc/pcie-keembay.c
> @@ -313,11 +313,11 @@ static const struct pci_epc_features keembay_pcie_epc_features = {
>  	.msi_capable		= true,
>  	.msix_capable		= true,
>  	.bar[BAR_0]		= { .only_64bit = true, },
> -	.bar[BAR_1]		= { .type = BAR_RESERVED, },
> +	.bar[BAR_1]		= { .type = BAR_64BIT_UPPER, },
>  	.bar[BAR_2]		= { .only_64bit = true, },
> -	.bar[BAR_3]		= { .type = BAR_RESERVED, },
> +	.bar[BAR_3]		= { .type = BAR_64BIT_UPPER, },
>  	.bar[BAR_4]		= { .only_64bit = true, },
> -	.bar[BAR_5]		= { .type = BAR_RESERVED, },
> +	.bar[BAR_5]		= { .type = BAR_64BIT_UPPER, },
>  	.align			= SZ_16K,
>  };
>  
> diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> index 18460f01b2c6..e55675b3840a 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> @@ -850,9 +850,9 @@ static const struct pci_epc_features qcom_pcie_epc_features = {
>  	.msi_capable = true,
>  	.align = SZ_4K,
>  	.bar[BAR_0] = { .only_64bit = true, },
> -	.bar[BAR_1] = { .type = BAR_RESERVED, },
> +	.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
>  	.bar[BAR_2] = { .only_64bit = true, },
> -	.bar[BAR_3] = { .type = BAR_RESERVED, },
> +	.bar[BAR_3] = { .type = BAR_64BIT_UPPER, },
>  };
>  
>  static const struct pci_epc_features *
> diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> index 06571d806ab3..31aa9a494dbc 100644
> --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> @@ -1993,7 +1993,7 @@ static const struct pci_epc_features tegra_pcie_epc_features = {
>  	.msi_capable = true,
>  	.bar[BAR_0] = { .type = BAR_FIXED, .fixed_size = SZ_1M,
>  			.only_64bit = true, },
> -	.bar[BAR_1] = { .type = BAR_RESERVED, },
> +	.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
>  	.bar[BAR_2] = { .type = BAR_RESERVED, },
>  	.bar[BAR_3] = { .type = BAR_RESERVED, },
>  	.bar[BAR_4] = { .type = BAR_RESERVED, },
> diff --git a/drivers/pci/controller/dwc/pcie-uniphier-ep.c b/drivers/pci/controller/dwc/pcie-uniphier-ep.c
> index d52753060970..f873a1659592 100644
> --- a/drivers/pci/controller/dwc/pcie-uniphier-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-uniphier-ep.c
> @@ -426,9 +426,9 @@ static const struct uniphier_pcie_ep_soc_data uniphier_pro5_data = {
>  		.msix_capable = false,
>  		.align = 1 << 16,
>  		.bar[BAR_0] = { .only_64bit = true, },
> -		.bar[BAR_1] = { .type = BAR_RESERVED, },
> +		.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
>  		.bar[BAR_2] = { .only_64bit = true, },
> -		.bar[BAR_3] = { .type = BAR_RESERVED, },
> +		.bar[BAR_3] = { .type = BAR_64BIT_UPPER, },
>  		.bar[BAR_4] = { .type = BAR_RESERVED, },
>  		.bar[BAR_5] = { .type = BAR_RESERVED, },
>  	},
> @@ -445,11 +445,11 @@ static const struct uniphier_pcie_ep_soc_data uniphier_nx1_data = {
>  		.msix_capable = false,
>  		.align = 1 << 12,
>  		.bar[BAR_0] = { .only_64bit = true, },
> -		.bar[BAR_1] = { .type = BAR_RESERVED, },
> +		.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
>  		.bar[BAR_2] = { .only_64bit = true, },
> -		.bar[BAR_3] = { .type = BAR_RESERVED, },
> +		.bar[BAR_3] = { .type = BAR_64BIT_UPPER, },
>  		.bar[BAR_4] = { .only_64bit = true, },
> -		.bar[BAR_5] = { .type = BAR_RESERVED, },
> +		.bar[BAR_5] = { .type = BAR_64BIT_UPPER, },
>  	},
>  };
>  
> diff --git a/drivers/pci/controller/pcie-rcar-ep.c b/drivers/pci/controller/pcie-rcar-ep.c
> index 657875ef4657..9b3f5391fabe 100644
> --- a/drivers/pci/controller/pcie-rcar-ep.c
> +++ b/drivers/pci/controller/pcie-rcar-ep.c
> @@ -440,13 +440,13 @@ static const struct pci_epc_features rcar_pcie_epc_features = {
>  	/* use 64-bit BARs so mark BAR[1,3,5] as reserved */
>  	.bar[BAR_0] = { .type = BAR_FIXED, .fixed_size = 128,
>  			.only_64bit = true, },
> -	.bar[BAR_1] = { .type = BAR_RESERVED, },
> +	.bar[BAR_1] = { .type = BAR_64BIT_UPPER, },
>  	.bar[BAR_2] = { .type = BAR_FIXED, .fixed_size = 256,
>  			.only_64bit = true, },
> -	.bar[BAR_3] = { .type = BAR_RESERVED, },
> +	.bar[BAR_3] = { .type = BAR_64BIT_UPPER, },
>  	.bar[BAR_4] = { .type = BAR_FIXED, .fixed_size = 256,
>  			.only_64bit = true, },
> -	.bar[BAR_5] = { .type = BAR_RESERVED, },
> +	.bar[BAR_5] = { .type = BAR_64BIT_UPPER, },
>  };
>  
>  static const struct pci_epc_features*
> diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
> index e546b3dbb240..1ad2f62963c8 100644
> --- a/drivers/pci/endpoint/pci-epc-core.c
> +++ b/drivers/pci/endpoint/pci-epc-core.c
> @@ -104,7 +104,8 @@ enum pci_barno pci_epc_get_next_free_bar(const struct pci_epc_features
>  
>  	for (i = bar; i < PCI_STD_NUM_BARS; i++) {
>  		/* If the BAR is not reserved, return it. */
> -		if (epc_features->bar[i].type != BAR_RESERVED)
> +		if (epc_features->bar[i].type != BAR_RESERVED &&
> +		    epc_features->bar[i].type != BAR_64BIT_UPPER)
>  			return i;
>  	}
>  
> diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
> index c021c7af175f..c22f8a6cf9a3 100644
> --- a/include/linux/pci-epc.h
> +++ b/include/linux/pci-epc.h
> @@ -192,12 +192,15 @@ struct pci_epc {
>   *		   NOTE: An EPC driver can currently only set a single supported
>   *		   size.
>   * @BAR_RESERVED: The BAR should not be touched by an EPF driver.
> + * @BAR_64BIT_UPPER: Should only be set on a BAR if the preceding BAR is marked
> + *		     as only_64bit.
>   */
>  enum pci_epc_bar_type {
>  	BAR_PROGRAMMABLE = 0,
>  	BAR_FIXED,
>  	BAR_RESIZABLE,
>  	BAR_RESERVED,
> +	BAR_64BIT_UPPER,
>  };
>  
>  /**
> @@ -207,7 +210,7 @@ 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. Additionally, the BAR succeeding
> - *		this BAR must be set to type BAR_RESERVED.
> + *		this BAR must be set to type BAR_64BIT_UPPER.
>   *
>   *		only_64bit should not be set on a BAR of type BAR_RESERVED.
>   *		(If BARx is a 64-bit BAR that an EPF driver is not allowed to
> -- 
> 2.53.0
> 

-- 
மணிவண்ணன் சதாசிவம்

Re: [PATCH v3 1/9] PCI: endpoint: Introduce pci_epc_bar_type BAR_64BIT_UPPER

[Niklas Cassel]

Hello Mani,

On Wed, Mar 11, 2026 at 12:05:59PM +0530, Manivannan Sadhasivam wrote:

(snip)

> This also brings the question, do we really need to mark the preceding BAR?

From a pure code PoV, marking the preceding BAR is enough even with the
current code:
https://github.com/torvalds/linux/blob/v7.0-rc3/drivers/pci/endpoint/pci-epc-core.c#L101-L103

However, the current documentation claims that the succeeding BAR must be
marked as BAR_RESERVED:
https://github.com/torvalds/linux/blob/v7.0-rc3/include/linux/pci-epc.h#L207-L210

I want to change this to BAR_64BIT_UPPER / BAR_64BIT_UPPER_BASE, so we can use
BAR_RESERVED for BARs that expose fixed hardware resources (e.g. eDMA regs).


Thus, an EPC driver does not strictly need mark the succeeding BAR with anything.
This was done mostly for clarity. (E.g. with BAR_64BIT_UPPER_BASE it is obvious
that this BAR cannot be a standalone 32-bit BAR.)

If we don't mark the succeeding BAR with anything, IMO, it is less obvious that
the succeeding BAR cannot be used as a standalone 32-bit BAR.

But... since the code already does the "right thing". We could simply nuke this
part of the documentation, and drop the .type for all BARs succeeding a
.only_64bit BAR, if you prefer that option over having a dedicated type for the
"upper base of a 64-bit BAR".


> Why can't we let the PCI EPC core to always assume that if the previous BAR
> has 'only_64bit' bit set, next BAR cannot be used as a standalone 32bit BAR?
> 
> I find it weird or redundant to mark both BARs.

Redundant, yes, but in my opinion marking both BARs makes it unambigious
that two BARs are used when a BAR is "only_64bit".

E.g. Manikanta originally wanted to add code comments for the upper part of
the 64-bit BAR:
https://lore.kernel.org/linux-pci/20260217-master-v1-2-727e26cdfaf5@nvidia.com/

Sure, we can just skip the .type for the succeeding BAR...
But is that really better than clearly showing that a "forced" 64-bit BAR will
always occupy two BARs?


Tell me what you prefer:
1) s/BAR_RESERVED/BAR_64BIT_UPPER_BASE/
2) Change documentation and drop .type for a BAR following a .only_64bit BAR.

And I will respin with that.


Kind regards,
Niklas

Re: [PATCH v3 1/9] PCI: endpoint: Introduce pci_epc_bar_type BAR_64BIT_UPPER

[Manivannan Sadhasivam]

On Wed, Mar 11, 2026 at 11:38:50AM +0100, Niklas Cassel wrote:
> Hello Mani,
> 
> On Wed, Mar 11, 2026 at 12:05:59PM +0530, Manivannan Sadhasivam wrote:
> 
> (snip)
> 
> > This also brings the question, do we really need to mark the preceding BAR?
> 
> From a pure code PoV, marking the preceding BAR is enough even with the
> current code:
> https://github.com/torvalds/linux/blob/v7.0-rc3/drivers/pci/endpoint/pci-epc-core.c#L101-L103
> 
> However, the current documentation claims that the succeeding BAR must be
> marked as BAR_RESERVED:
> https://github.com/torvalds/linux/blob/v7.0-rc3/include/linux/pci-epc.h#L207-L210
> 
> I want to change this to BAR_64BIT_UPPER / BAR_64BIT_UPPER_BASE, so we can use
> BAR_RESERVED for BARs that expose fixed hardware resources (e.g. eDMA regs).
> 
> 
> Thus, an EPC driver does not strictly need mark the succeeding BAR with anything.
> This was done mostly for clarity. (E.g. with BAR_64BIT_UPPER_BASE it is obvious
> that this BAR cannot be a standalone 32-bit BAR.)
> 
> If we don't mark the succeeding BAR with anything, IMO, it is less obvious that
> the succeeding BAR cannot be used as a standalone 32-bit BAR.
> 
> But... since the code already does the "right thing". We could simply nuke this
> part of the documentation, and drop the .type for all BARs succeeding a
> .only_64bit BAR, if you prefer that option over having a dedicated type for the
> "upper base of a 64-bit BAR".
> 

Yes, let's just remove that comment.

> 
> > Why can't we let the PCI EPC core to always assume that if the previous BAR
> > has 'only_64bit' bit set, next BAR cannot be used as a standalone 32bit BAR?
> > 
> > I find it weird or redundant to mark both BARs.
> 
> Redundant, yes, but in my opinion marking both BARs makes it unambigious
> that two BARs are used when a BAR is "only_64bit".
> 
> E.g. Manikanta originally wanted to add code comments for the upper part of
> the 64-bit BAR:
> https://lore.kernel.org/linux-pci/20260217-master-v1-2-727e26cdfaf5@nvidia.com/
> 
> Sure, we can just skip the .type for the succeeding BAR...
> But is that really better than clearly showing that a "forced" 64-bit BAR will
> always occupy two BARs?
> 

To whom are we showing? If it is a developer, then he should understand that a
64bit BAR occupies two consecutive 32bit BARs. The flag should only be set for
the code not for the reader.

> 
> Tell me what you prefer:
> 1) s/BAR_RESERVED/BAR_64BIT_UPPER_BASE/
> 2) Change documentation and drop .type for a BAR following a .only_64bit BAR.
> 

Let's go with 2.

- Mani

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