[RFC PATCH] PCI: keystone: Refactor ks_pcie_v3_65_add_bus() functionality

[Siddharth Vadapalli]

The .add_bus() callback "ks_pcie_v3_65_add_bus()" exists to setup BAR0 for
MSI configuration. This method is expected to be invoked after the
enumeration of endpoints for the v3.65a DWC PCIe IP Controller.

Based on the discussion at [0], the contents of "ks_pcie_v3_65_add_bus()"
can be moved to the .host_init callback "ks_pcie_host_init()" and the
.add_bus callback within "struct pci_ops ks_pcie_ops" is no longer
required.

Hence, for the v3.65a DWC PCIe IP Controllers (!ks_pcie->is_am6), perform
the MSI specific configuration of BAR0 within "ks_pcie_host_init()"
itself.

[0] https://lore.kernel.org/r/20231019220847.GA1413474@bhelgaas/

Suggested-by: Serge Semin <fancer.lancer at gmail.com>
Suggested-by: Bjorn Helgaas <helgaas at kernel.org>
Signed-off-by: Siddharth Vadapalli <s-vadapalli at ti.com>
---
Hello,

This patch is based on linux-next tagged next-20231027.
This patch depends on the patch at:
https://lore.kernel.org/r/20231019081330.2975470-1-s-vadapalli@ti.com/

Regards,
Siddharth.

 drivers/pci/controller/dwc/pci-keystone.c | 51 ++++++++---------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
index e9245b7632c5..369f5e556df3 100644
--- a/drivers/pci/controller/dwc/pci-keystone.c
+++ b/drivers/pci/controller/dwc/pci-keystone.c
@@ -447,44 +447,10 @@ static struct pci_ops ks_child_pcie_ops = {
 	.write = pci_generic_config_write,
 };
 
-/**
- * ks_pcie_v3_65_add_bus() - keystone add_bus post initialization
- * @bus: A pointer to the PCI bus structure.
- *
- * This sets BAR0 to enable inbound access for MSI_IRQ register
- */
-static int ks_pcie_v3_65_add_bus(struct pci_bus *bus)
-{
-	struct dw_pcie_rp *pp = bus->sysdata;
-	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
-	struct keystone_pcie *ks_pcie = to_keystone_pcie(pci);
-
-	if (!pci_is_root_bus(bus))
-		return 0;
-
-	/* Configure and set up BAR0 */
-	ks_pcie_set_dbi_mode(ks_pcie);
-
-	/* Enable BAR0 */
-	dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, 1);
-	dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, SZ_4K - 1);
-
-	ks_pcie_clear_dbi_mode(ks_pcie);
-
-	 /*
-	  * For BAR0, just setting bus address for inbound writes (MSI) should
-	  * be sufficient.  Use physical address to avoid any conflicts.
-	  */
-	dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, ks_pcie->app.start);
-
-	return 0;
-}
-
 static struct pci_ops ks_pcie_ops = {
 	.map_bus = dw_pcie_own_conf_map_bus,
 	.read = pci_generic_config_read,
 	.write = pci_generic_config_write,
-	.add_bus = ks_pcie_v3_65_add_bus,
 };
 
 static struct pci_ops ks_pcie_am6_ops = {
@@ -834,6 +800,23 @@ static int __init ks_pcie_host_init(struct dw_pcie_rp *pp)
 	if (ret < 0)
 		return ret;
 
+	if (!ks_pcie->is_am6) {
+		/* Configure and set up BAR0 */
+		ks_pcie_set_dbi_mode(ks_pcie);
+
+		/* Enable BAR0 */
+		dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, 1);
+		dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, SZ_4K - 1);
+
+		ks_pcie_clear_dbi_mode(ks_pcie);
+
+		/*
+		 * For BAR0, just setting bus address for inbound writes (MSI) should
+		 * be sufficient.  Use physical address to avoid any conflicts.
+		 */
+		dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, ks_pcie->app.start);
+	}
+
 #ifdef CONFIG_ARM
 	/*
 	 * PCIe access errors that result into OCP errors are caught by ARM as
-- 
2.34.1