PCI: dwc: Add start_link/stop_link inlines

Factor out this pattern:

if (!pci->ops || !pci->ops->start_link)
return -EINVAL;

return pci->ops->start_link(pci);

into a new dw_pcie_start_link() wrapper and do the same for the stop_link()
method.

Note that dw_pcie_ep_start() previously returned -EINVAL if there was no
platform start_link() method, which didn't make much sense since that is
not an error. It will now return 0 in that case.

As a side-effect, drop the empty start_link() and dummy dw_pcie_ops
instances from the generic DW PCIe and Layerscape EP platform drivers.

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Serge Semin <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Reviewed-by: Manivannan Sadhasivam <[e-mail]>

drivers/pci/controller/dwc/pci-layerscape-ep.c

···
 	const struct ls_pcie_ep_drvdata *drvdata;
 };
 
-static int ls_pcie_establish_link(struct dw_pcie *pci)
-{
-	return 0;
-}
-
-static const struct dw_pcie_ops dw_ls_pcie_ep_ops = {
-	.start_link = ls_pcie_establish_link,
-};
-
 static const struct pci_epc_features*
 ls_pcie_ep_get_features(struct dw_pcie_ep *ep)
 {
···
 
 static const struct ls_pcie_ep_drvdata ls1_ep_drvdata = {
 	.ops = &ls_pcie_ep_ops,
-	.dw_pcie_ops = &dw_ls_pcie_ep_ops,
 };
 
 static const struct ls_pcie_ep_drvdata ls2_ep_drvdata = {
 	.func_offset = 0x20000,
 	.ops = &ls_pcie_ep_ops,
-	.dw_pcie_ops = &dw_ls_pcie_ep_ops,
 };
 
 static const struct ls_pcie_ep_drvdata lx2_ep_drvdata = {
 	.func_offset = 0x8000,
 	.ops = &ls_pcie_ep_ops,
-	.dw_pcie_ops = &dw_ls_pcie_ep_ops,
 };
 
 static const struct of_device_id ls_pcie_ep_of_match[] = {

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

···
 	struct dw_pcie_ep *ep = epc_get_drvdata(epc);
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
 
-	if (pci->ops && pci->ops->stop_link)
-		pci->ops->stop_link(pci);
+	dw_pcie_stop_link(pci);
 }
 
 static int dw_pcie_ep_start(struct pci_epc *epc)
···
 	struct dw_pcie_ep *ep = epc_get_drvdata(epc);
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
 
-	if (!pci->ops || !pci->ops->start_link)
-		return -EINVAL;
-
-	return pci->ops->start_link(pci);
+	return dw_pcie_start_link(pci);
 }
 
 static const struct pci_epc_features*

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

···
 
 	dw_pcie_setup_rc(pp);
 
-	if (!dw_pcie_link_up(pci) && pci->ops && pci->ops->start_link) {
-		ret = pci->ops->start_link(pci);
+	if (!dw_pcie_link_up(pci)) {
+		ret = dw_pcie_start_link(pci);
 		if (ret)
 			goto err_free_msi;
 	}
···
 	return 0;
 
 err_stop_link:
-	if (pci->ops && pci->ops->stop_link)
-		pci->ops->stop_link(pci);
+	dw_pcie_stop_link(pci);
 
 err_free_msi:
 	if (pp->has_msi_ctrl)
···
 	pci_stop_root_bus(pp->bridge->bus);
 	pci_remove_root_bus(pp->bridge->bus);
 
-	if (pci->ops && pci->ops->stop_link)
-		pci->ops->stop_link(pci);
+	dw_pcie_stop_link(pci);
 
 	if (pp->has_msi_ctrl)
 		dw_pcie_free_msi(pp);

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

···
 static const struct dw_pcie_host_ops dw_plat_pcie_host_ops = {
 };
 
-static int dw_plat_pcie_establish_link(struct dw_pcie *pci)
-{
-	return 0;
-}
-
-static const struct dw_pcie_ops dw_pcie_ops = {
-	.start_link = dw_plat_pcie_establish_link,
-};
-
 static void dw_plat_pcie_ep_init(struct dw_pcie_ep *ep)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
···
 		return -ENOMEM;
 
 	pci->dev = dev;
-	pci->ops = &dw_pcie_ops;
 
 	dw_plat_pcie->pci = pci;
 	dw_plat_pcie->mode = mode;

drivers/pci/controller/dwc/pcie-designware.h

···
 	dw_pcie_writel_dbi(pci, reg, val);
 }
 
+static inline int dw_pcie_start_link(struct dw_pcie *pci)
+{
+	if (pci->ops && pci->ops->start_link)
+		return pci->ops->start_link(pci);
+
+	return 0;
+}
+
+static inline void dw_pcie_stop_link(struct dw_pcie *pci)
+{
+	if (pci->ops && pci->ops->stop_link)
+		pci->ops->stop_link(pci);
+}
+
 #ifdef CONFIG_PCIE_DW_HOST
 irqreturn_t dw_handle_msi_irq(struct pcie_port *pp);
 void dw_pcie_setup_rc(struct pcie_port *pp);