PCI: endpoint: Align pci_epc_set_msi(), pci_epc_ops::set_msi() nr_irqs encoding

The kdoc for pci_epc_set_msi() says:
"Invoke to set the required number of MSI interrupts."

The kdoc for the callback pci_epc_ops::set_msi() says:
"ops to set the requested number of MSI interrupts in the MSI capability
register"

pci_epc_ops::set_msi() does however expect the parameter 'interrupts' to be
in the encoding as defined by the Multiple Message Capable (MMC) field of
the MSI capability structure. Nowhere in the kdoc does it say that the
number of interrupts should be in MMC encoding.

It is very confusing that the API pci_epc_set_msi() and the callback
function pci_epc_ops::set_msi() both take a parameter named 'interrupts',
but they expect completely different encodings.

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

Also rename the parameter 'interrupts' to 'nr_irqs', in both the wrapper
function and the callback function, such that the name is unambiguous.

[bhelgaas: more specific subject]

Signed-off-by: Niklas Cassel <[email protected]>
Signed-off-by: Manivannan Sadhasivam <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Cc: [email protected] # this is simply a cleanup
Link: https://patch.msgid.link/[email protected]

Author: floatious

drivers/pci/controller/cadence/pcie-cadence-ep.c

@@ -220,10 +220,11 @@ static void cdns_pcie_ep_unmap_addr(struct pci_epc *epc, u8 fn, u8 vfn,
 	clear_bit(r, &ep->ob_region_map);
 }
 
-static int cdns_pcie_ep_set_msi(struct pci_epc *epc, u8 fn, u8 vfn, u8 mmc)
+static int cdns_pcie_ep_set_msi(struct pci_epc *epc, u8 fn, u8 vfn, u8 nr_irqs)
 {
 	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
 	struct cdns_pcie *pcie = &ep->pcie;
+	u8 mmc = order_base_2(nr_irqs);
 	u32 cap = CDNS_PCIE_EP_FUNC_MSI_CAP_OFFSET;
 	u16 flags;
 

drivers/pci/controller/dwc/pcie-designware-ep.c

@@ -536,11 +536,12 @@ static int dw_pcie_ep_get_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no)
 }
 
 static int dw_pcie_ep_set_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
-			      u8 interrupts)
+			      u8 nr_irqs)
 {
 	struct dw_pcie_ep *ep = epc_get_drvdata(epc);
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
 	struct dw_pcie_ep_func *ep_func;
+	u8 mmc = order_base_2(nr_irqs);
 	u32 val, reg;
 
 	ep_func = dw_pcie_ep_get_func_from_ep(ep, func_no);
@@ -550,7 +551,7 @@ static int dw_pcie_ep_set_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 	reg = ep_func->msi_cap + PCI_MSI_FLAGS;
 	val = dw_pcie_ep_readw_dbi(ep, func_no, reg);
 	val &= ~PCI_MSI_FLAGS_QMASK;
-	val |= FIELD_PREP(PCI_MSI_FLAGS_QMASK, interrupts);
+	val |= FIELD_PREP(PCI_MSI_FLAGS_QMASK, mmc);
 	dw_pcie_dbi_ro_wr_en(pci);
 	dw_pcie_ep_writew_dbi(ep, func_no, reg, val);
 	dw_pcie_dbi_ro_wr_dis(pci);

drivers/pci/controller/pcie-rcar-ep.c

@@ -256,15 +256,15 @@ static void rcar_pcie_ep_clear_bar(struct pci_epc *epc, u8 fn, u8 vfn,
 	clear_bit(atu_index + 1, ep->ib_window_map);
 }
 
-static int rcar_pcie_ep_set_msi(struct pci_epc *epc, u8 fn, u8 vfn,
-				u8 interrupts)
+static int rcar_pcie_ep_set_msi(struct pci_epc *epc, u8 fn, u8 vfn, u8 nr_irqs)
 {
 	struct rcar_pcie_endpoint *ep = epc_get_drvdata(epc);
 	struct rcar_pcie *pcie = &ep->pcie;
+	u8 mmc = order_base_2(nr_irqs);
 	u32 flags;
 
 	flags = rcar_pci_read_reg(pcie, MSICAP(fn));
-	flags |= interrupts << MSICAP0_MMESCAP_OFFSET;
+	flags |= mmc << MSICAP0_MMESCAP_OFFSET;
 	rcar_pci_write_reg(pcie, flags, MSICAP(fn));
 
 	return 0;

drivers/pci/controller/pcie-rockchip-ep.c

@@ -308,18 +308,19 @@ static void rockchip_pcie_ep_unmap_addr(struct pci_epc *epc, u8 fn, u8 vfn,
 }
 
 static int rockchip_pcie_ep_set_msi(struct pci_epc *epc, u8 fn, u8 vfn,
-				    u8 multi_msg_cap)
+				    u8 nr_irqs)
 {
 	struct rockchip_pcie_ep *ep = epc_get_drvdata(epc);
 	struct rockchip_pcie *rockchip = &ep->rockchip;
+	u8 mmc = order_base_2(nr_irqs);
 	u32 flags;
 
 	flags = rockchip_pcie_read(rockchip,
 				   ROCKCHIP_PCIE_EP_FUNC_BASE(fn) +
 				   ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
 	flags &= ~ROCKCHIP_PCIE_EP_MSI_CTRL_MMC_MASK;
 	flags |=
-	   (multi_msg_cap << ROCKCHIP_PCIE_EP_MSI_CTRL_MMC_OFFSET) |
+	   (mmc << ROCKCHIP_PCIE_EP_MSI_CTRL_MMC_OFFSET) |
 	   (PCI_MSI_FLAGS_64BIT << ROCKCHIP_PCIE_EP_MSI_FLAGS_OFFSET);
 	flags &= ~ROCKCHIP_PCIE_EP_MSI_CTRL_MASK_MSI_CAP;
 	rockchip_pcie_write(rockchip, flags,

drivers/pci/endpoint/pci-epc-core.c

@@ -302,28 +302,25 @@ EXPORT_SYMBOL_GPL(pci_epc_get_msi);
  * @epc: the EPC device on which MSI has to be configured
  * @func_no: the physical endpoint function number in the EPC device
  * @vfunc_no: the virtual endpoint function number in the physical function
- * @interrupts: number of MSI interrupts required by the EPF
+ * @nr_irqs: number of MSI interrupts required by the EPF
  *
  * Invoke to set the required number of MSI interrupts.
  */
-int pci_epc_set_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no, u8 interrupts)
+int pci_epc_set_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no, u8 nr_irqs)
 {
 	int ret;
-	u8 encode_int;
 
 	if (!pci_epc_function_is_valid(epc, func_no, vfunc_no))
 		return -EINVAL;
 
-	if (interrupts < 1 || interrupts > 32)
+	if (nr_irqs < 1 || nr_irqs > 32)
 		return -EINVAL;
 
 	if (!epc->ops->set_msi)
 		return 0;
 
-	encode_int = order_base_2(interrupts);
-
 	mutex_lock(&epc->lock);
-	ret = epc->ops->set_msi(epc, func_no, vfunc_no, encode_int);
+	ret = epc->ops->set_msi(epc, func_no, vfunc_no, nr_irqs);
 	mutex_unlock(&epc->lock);
 
 	return ret;

include/linux/pci-epc.h

@@ -100,7 +100,7 @@ struct pci_epc_ops {
 	void	(*unmap_addr)(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 			      phys_addr_t addr);
 	int	(*set_msi)(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
-			   u8 interrupts);
+			   u8 nr_irqs);
 	int	(*get_msi)(struct pci_epc *epc, u8 func_no, u8 vfunc_no);
 	int	(*set_msix)(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 			    u16 interrupts, enum pci_barno, u32 offset);
@@ -286,8 +286,7 @@ int pci_epc_map_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 		     u64 pci_addr, size_t size);
 void pci_epc_unmap_addr(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 			phys_addr_t phys_addr);
-int pci_epc_set_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
-		    u8 interrupts);
+int pci_epc_set_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no, u8 nr_irqs);
 int pci_epc_get_msi(struct pci_epc *epc, u8 func_no, u8 vfunc_no);
 int pci_epc_set_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 		     u16 interrupts, enum pci_barno, u32 offset);