[PATCH v4] PCI: keystone: Fix pci_ops for AM654x SoC

[Siddharth Vadapalli <s-vadapalli@ti.com>]

In the process of converting .scan_bus() callbacks to .add_bus(), the
ks_pcie_v3_65_scan_bus() function was changed to ks_pcie_v3_65_add_bus().
The .scan_bus() method belonged to ks_pcie_host_ops which was specific
to controller version 3.65a, while the .add_bus() method had been added
to ks_pcie_ops which is shared between the controller versions 3.65a and
4.90a. Neither the older ks_pcie_v3_65_scan_bus() method, nor the newer
ks_pcie_v3_65_add_bus() method are applicable to the controller version
4.90a which is present in AM654x SoCs.

Thus, as a fix, move the contents of "ks_pcie_v3_65_add_bus()" to the
.host_init callback "ks_pcie_host_init()" and execute it only for non
AM654x SoC devices which have the v3.65a DWC PCIe IP Controllers.

Fixes: 6ab15b5e7057 ("PCI: dwc: keystone: Convert .scan_bus() callback to use add_bus")
Suggested-by: Serge Semin <fancer.lancer@gmail.com>
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
---

Hello,

This patch is based on linux-next tagged next-20240325.
This patch is technically the next version for the v3 patch at:
https://patchwork.kernel.org/project/linux-pci/patch/20231019081330.2975470-1-s-vadapalli@ti.com/
but the implementation is based on the RFC patch at:
https://patchwork.kernel.org/project/linux-pci/patch/20231027084159.4166188-1-s-vadapalli@ti.com/
Since the RFC patch mentioned above fixes the same issue being
fixed by the v3 patch, I have dropped the v3 patch and am using
the RFC patch since it is a cleaner implementation and was discussed at:
https://lore.kernel.org/r/20231019220847.GA1413474@bhelgaas/

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 844de4418724..f45bdeac520a 100644
--- a/drivers/pci/controller/dwc/pci-keystone.c
+++ b/drivers/pci/controller/dwc/pci-keystone.c
@@ -445,44 +445,10 @@ 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,
 };
 
 /**
@@ -822,6 +788,23 @@ 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
-- 
2.40.1