[PATCH v3 6/6] PCI: endpoint: Cleanup set_msix() callback

[Niklas Cassel <cassel@kernel.org>]

The kdoc for pci_epc_set_msix() says:
"Invoke to set the required number of MSI-X interrupts."
the kdoc for the callback pci_epc_ops->set_msix() says:
"ops to set the requested number of MSI-X interrupts in the MSI-X
capability register"

pci_epc_ops->set_msix() does however expect the parameter 'interrupts' to
be in the encoding as defined by the Table Size field.

Nowhere in the kdoc does it say that the number of interrupts should be
in Table Size encoding.

Thus, it is very confusing that the wrapper function (pci_epc_set_msix())
and the callback function (pci_epc_ops->set_msix()) both take a parameter
named interrupts, but they both expect completely different encodings.

Cleanup the API so that the wrapper function and the callback function
will 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.

Cc: <stable+noautosel@kernel.org> # this is simply a cleanup
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/controller/cadence/pcie-cadence-ep.c |  8 +++-----
 drivers/pci/controller/dwc/pcie-designware-ep.c  |  7 +++----
 drivers/pci/endpoint/pci-epc-core.c              | 11 +++++------
 include/linux/pci-epc.h                          |  6 +++---
 4 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/drivers/pci/controller/cadence/pcie-cadence-ep.c b/drivers/pci/controller/cadence/pcie-cadence-ep.c
index f09f29ed27ed..0e9ebe956e7a 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-ep.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-ep.c
@@ -286,21 +286,19 @@ static int cdns_pcie_ep_get_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no)
 }
 
 static int cdns_pcie_ep_set_msix(struct pci_epc *epc, u8 fn, u8 vfn,
-				 u16 interrupts, enum pci_barno bir,
-				 u32 offset)
+				 u16 nr_irqs, enum pci_barno bir, u32 offset)
 {
 	struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
 	struct cdns_pcie *pcie = &ep->pcie;
 	u32 cap = CDNS_PCIE_EP_FUNC_MSIX_CAP_OFFSET;
 	u32 val, reg;
-	u16 actual_interrupts = interrupts + 1;
 
 	fn = cdns_pcie_get_fn_from_vfn(pcie, fn, vfn);
 
 	reg = cap + PCI_MSIX_FLAGS;
 	val = cdns_pcie_ep_fn_readw(pcie, fn, reg);
 	val &= ~PCI_MSIX_FLAGS_QSIZE;
-	val |= interrupts; /* 0's based value */
+	val |= nr_irqs - 1; /* encoded as N-1 */
 	cdns_pcie_ep_fn_writew(pcie, fn, reg, val);
 
 	/* Set MSI-X BAR and offset */
@@ -310,7 +308,7 @@ static int cdns_pcie_ep_set_msix(struct pci_epc *epc, u8 fn, u8 vfn,
 
 	/* Set PBA BAR and offset.  BAR must match MSI-X BAR */
 	reg = cap + PCI_MSIX_PBA;
-	val = (offset + (actual_interrupts * PCI_MSIX_ENTRY_SIZE)) | bir;
+	val = (offset + (nr_irqs * PCI_MSIX_ENTRY_SIZE)) | bir;
 	cdns_pcie_ep_fn_writel(pcie, fn, reg, val);
 
 	return 0;
diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 230e82674591..6770318c0636 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -580,13 +580,12 @@ static int dw_pcie_ep_get_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no)
 }
 
 static int dw_pcie_ep_set_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
-			       u16 interrupts, enum pci_barno bir, u32 offset)
+			       u16 nr_irqs, enum pci_barno bir, u32 offset)
 {
 	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;
 	u32 val, reg;
-	u16 actual_interrupts = interrupts + 1;
 
 	ep_func = dw_pcie_ep_get_func_from_ep(ep, func_no);
 	if (!ep_func || !ep_func->msix_cap)
@@ -597,7 +596,7 @@ static int dw_pcie_ep_set_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 	reg = ep_func->msix_cap + PCI_MSIX_FLAGS;
 	val = dw_pcie_ep_readw_dbi(ep, func_no, reg);
 	val &= ~PCI_MSIX_FLAGS_QSIZE;
-	val |= interrupts; /* 0's based value */
+	val |= nr_irqs - 1; /* encoded as N-1 */
 	dw_pcie_writew_dbi(pci, reg, val);
 
 	reg = ep_func->msix_cap + PCI_MSIX_TABLE;
@@ -605,7 +604,7 @@ static int dw_pcie_ep_set_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 	dw_pcie_ep_writel_dbi(ep, func_no, reg, val);
 
 	reg = ep_func->msix_cap + PCI_MSIX_PBA;
-	val = (offset + (actual_interrupts * PCI_MSIX_ENTRY_SIZE)) | bir;
+	val = (offset + (nr_irqs * PCI_MSIX_ENTRY_SIZE)) | bir;
 	dw_pcie_ep_writel_dbi(ep, func_no, reg, val);
 
 	dw_pcie_dbi_ro_wr_dis(pci);
diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index ea698551f9d8..ca7f19cc973a 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -361,29 +361,28 @@ EXPORT_SYMBOL_GPL(pci_epc_get_msix);
  * @epc: the EPC device on which MSI-X 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-X interrupts required by the EPF
+ * @nr_irqs: number of MSI-X interrupts required by the EPF
  * @bir: BAR where the MSI-X table resides
  * @offset: Offset pointing to the start of MSI-X table
  *
  * Invoke to set the required number of MSI-X interrupts.
  */
-int pci_epc_set_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
-		     u16 interrupts, enum pci_barno bir, u32 offset)
+int pci_epc_set_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no, u16 nr_irqs,
+		     enum pci_barno bir, u32 offset)
 {
 	int ret;
 
 	if (!pci_epc_function_is_valid(epc, func_no, vfunc_no))
 		return -EINVAL;
 
-	if (interrupts < 1 || interrupts > 2048)
+	if (nr_irqs < 1 || nr_irqs > 2048)
 		return -EINVAL;
 
 	if (!epc->ops->set_msix)
 		return 0;
 
 	mutex_lock(&epc->lock);
-	ret = epc->ops->set_msix(epc, func_no, vfunc_no, interrupts - 1, bir,
-				 offset);
+	ret = epc->ops->set_msix(epc, func_no, vfunc_no, nr_irqs, bir, offset);
 	mutex_unlock(&epc->lock);
 
 	return ret;
diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index 15d10c07c9f1..4286bfdbfdfa 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -103,7 +103,7 @@ struct pci_epc_ops {
 			   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);
+			    u16 nr_irqs, enum pci_barno, u32 offset);
 	int	(*get_msix)(struct pci_epc *epc, u8 func_no, u8 vfunc_no);
 	int	(*raise_irq)(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 			     unsigned int type, u16 interrupt_num);
@@ -288,8 +288,8 @@ 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 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);
+int pci_epc_set_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no, u16 nr_irqs,
+		     enum pci_barno, u32 offset);
 int pci_epc_get_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no);
 int pci_epc_map_msi_irq(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 			phys_addr_t phys_addr, u8 interrupt_num,
-- 
2.49.0