PCI: endpoint: Align pci_epc_get_msi(), pci_epc_ops::get_msi() return value encoding

The kdoc for API pci_epc_get_msi() says:
"Invoke to get the number of MSI interrupts allocated by the RC"

The kdoc for the callback pci_epc_ops::get_msi() says:
"ops to get the number of MSI interrupts allocated by the RC from
the MSI capability register"

pci_epc_ops::get_msi() does however return the number of interrupts in the
encoding as defined by the Multiple Message Enable (MME) field of the MSI
Capability structure.

Nowhere in the kdoc does it say that the returned number of interrupts is
in MME encoding. It is very confusing that the API pci_epc_get_msi() and
the callback function pci_epc_ops::get_msi() don't return the same value.

Clean up the API and the callback function to have the same semantics,
i.e. return the number of interrupts, regardless of the internal encoding
of that value.

[bhelgaas: more specific subject]

Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Cc: stable+noautosel@kernel.org # this is simply a cleanup
Link: https://patch.msgid.link/20250514074313.283156-11-cassel@kernel.org

5 files changed, 5 insertions, 7 deletions

diff --git a/drivers/pci/controller/cadence/pcie-cadence-ep.c b/drivers/pci/controller/cadence/pcie-cadence-ep.c
index 112ae200b393..78b4d009cd04 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-ep.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-ep.c
@@ -262,7 +262,7 @@ static int cdns_pcie_ep_get_msi(struct pci_epc *epc, u8 fn, u8 vfn)
 	 */
 	mme = FIELD_GET(PCI_MSI_FLAGS_QSIZE, flags);
 
-	return mme;
+	return 1 << mme;
 }
 
 static int cdns_pcie_ep_get_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no)
diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 24026f3f3413..03597551f4cd 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -532,7 +532,7 @@ static int dw_pcie_ep_get_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no)
 
 	val = FIELD_GET(PCI_MSI_FLAGS_QSIZE, val);
 
-	return val;
+	return 1 << val;
 }
 
 static int dw_pcie_ep_set_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
diff --git a/drivers/pci/controller/pcie-rcar-ep.c b/drivers/pci/controller/pcie-rcar-ep.c
index c5e0d025bc43..9da39a4617b6 100644
--- a/drivers/pci/controller/pcie-rcar-ep.c
+++ b/drivers/pci/controller/pcie-rcar-ep.c
@@ -280,7 +280,7 @@ static int rcar_pcie_ep_get_msi(struct pci_epc *epc, u8 fn, u8 vfn)
 	if (!(flags & MSICAP0_MSIE))
 		return -EINVAL;
 
-	return ((flags & MSICAP0_MMESE_MASK) >> MSICAP0_MMESE_OFFSET);
+	return 1 << ((flags & MSICAP0_MMESE_MASK) >> MSICAP0_MMESE_OFFSET);
 }
 
 static int rcar_pcie_ep_map_addr(struct pci_epc *epc, u8 fn, u8 vfn,
diff --git a/drivers/pci/controller/pcie-rockchip-ep.c b/drivers/pci/controller/pcie-rockchip-ep.c
index 85ea36df2f59..85ca7d9b4c77 100644
--- a/drivers/pci/controller/pcie-rockchip-ep.c
+++ b/drivers/pci/controller/pcie-rockchip-ep.c
@@ -340,8 +340,8 @@ static int rockchip_pcie_ep_get_msi(struct pci_epc *epc, u8 fn, u8 vfn)
 	if (!(flags & ROCKCHIP_PCIE_EP_MSI_CTRL_ME))
 		return -EINVAL;
 
-	return ((flags & ROCKCHIP_PCIE_EP_MSI_CTRL_MME_MASK) >>
-			ROCKCHIP_PCIE_EP_MSI_CTRL_MME_OFFSET);
+	return 1 << ((flags & ROCKCHIP_PCIE_EP_MSI_CTRL_MME_MASK) >>
+		     ROCKCHIP_PCIE_EP_MSI_CTRL_MME_OFFSET);
 }
 
 static void rockchip_pcie_ep_assert_intx(struct rockchip_pcie_ep *ep, u8 fn,
diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index beabea00af91..cc1456bd188e 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -293,8 +293,6 @@ int pci_epc_get_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no)
 	if (interrupt < 0)
 		return 0;
 
-	interrupt = 1 << interrupt;
-
 	return interrupt;
 }
 EXPORT_SYMBOL_GPL(pci_epc_get_msi);