[PATCH v2 4/4] PCI: dwc: Fix missing iATU setup when ECAM is enabled

[Niklas Cassel <cassel@kernel.org>]

From: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>

When ECAM is enabled, the driver skipped calling dw_pcie_iatu_setup()
before configuring ECAM iATU entries. This left IO and MEM outbound
windows unprogrammed, resulting in broken IO transactions. Additionally,
dw_pcie_config_ecam_iatu() was only called during host initialization,
so ECAM-related iATU entries were not restored after suspend/resume,
leading to failures in configuration space access

To resolve these issues, the ECAM iATU configuration is moved into
dw_pcie_iatu_setup(), and dw_pcie_iatu_setup() is invoked when ECAM is
enabled.

Furthermore, error checks are added in dw_pcie_prog_outbound_atu() and
dw_pcie_prog_inbound_atu() so that an error is returned if trying to
programming an iATU that is outside the number of iATUs provided by
the controller.

Fixes: f6fd357f7afb ("PCI: dwc: Prepare the driver for enabling ECAM mechanism using iATU 'CFG Shift Feature'")
Reported-by: Maciej W. Rozycki <macro@orcam.me.uk>
Closes: https://lore.kernel.org/all/alpine.DEB.2.21.2511280256260.36486@angie.orcam.me.uk/
Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Co-developed-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 .../pci/controller/dwc/pcie-designware-host.c | 30 +++++++++++--------
 drivers/pci/controller/dwc/pcie-designware.c  |  6 ++++
 2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 76be24af7cfd..ef66a031f0bb 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -441,7 +441,7 @@ static int dw_pcie_config_ecam_iatu(struct dw_pcie_rp *pp)
 	/*
 	 * Root bus under the host bridge doesn't require any iATU configuration
 	 * as DBI region will be used to access root bus config space.
-	 * Immediate bus under Root Bus, needs type 0 iATU configuration and
+	 * Immediate bus under Root Bus needs type 0 iATU configuration and
 	 * remaining buses need type 1 iATU configuration.
 	 */
 	atu.index = 0;
@@ -641,14 +641,6 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
 	if (ret)
 		goto err_free_msi;
 
-	if (pp->ecam_enabled) {
-		ret = dw_pcie_config_ecam_iatu(pp);
-		if (ret) {
-			dev_err(dev, "Failed to configure iATU in ECAM mode\n");
-			goto err_free_msi;
-		}
-	}
-
 	/*
 	 * Allocate the resource for MSG TLP before programming the iATU
 	 * outbound window in dw_pcie_setup_rc(). Since the allocation depends
@@ -915,8 +907,21 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
 	 * NOTE: For outbound address translation, outbound iATU at index 0 is
 	 * reserved for CFG IOs (dw_pcie_other_conf_map_bus()), thus start at
 	 * index 1.
+	 *
+	 * If using ECAM, outbound iATU at index 0 and index 1 is reserved for
+	 * CFG IOs.
 	 */
-	ob_iatu_index_to_use = 1;
+	if (pp->ecam_enabled) {
+		ob_iatu_index_to_use = 2;
+		ret = dw_pcie_config_ecam_iatu(pp);
+		if (ret) {
+			dev_err(pci->dev, "Failed to configure iATU in ECAM mode\n");
+			return ret;
+		}
+	} else {
+		ob_iatu_index_to_use = 1;
+	}
+
 	resource_list_for_each_entry(entry, &pp->bridge->windows) {
 		resource_size_t res_size;
 
@@ -1157,9 +1162,10 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
 	/*
 	 * If the platform provides its own child bus config accesses, it means
 	 * the platform uses its own address translation component rather than
-	 * ATU, so we should not program the ATU here.
+	 * ATU, so we should not program the ATU here. If ECAM is enabled,
+	 * config space access goes through ATU, so set up ATU here.
 	 */
-	if (pp->bridge->child_ops == &dw_child_pcie_ops) {
+	if (pp->bridge->child_ops == &dw_child_pcie_ops || pp->ecam_enabled) {
 		ret = dw_pcie_iatu_setup(pp);
 		if (ret)
 			return ret;
diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 2fa9f6ee149e..225897c87c49 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -531,6 +531,9 @@ int dw_pcie_prog_outbound_atu(struct dw_pcie *pci,
 	u32 retries, val;
 	u64 limit_addr;
 
+	if (!(atu->index < pci->num_ob_windows))
+		return -ENOSPC;
+
 	limit_addr = parent_bus_addr + atu->size - 1;
 
 	if ((limit_addr & ~pci->region_limit) != (parent_bus_addr & ~pci->region_limit) ||
@@ -604,6 +607,9 @@ int dw_pcie_prog_inbound_atu(struct dw_pcie *pci, int index, int type,
 	u64 limit_addr = pci_addr + size - 1;
 	u32 retries, val;
 
+	if (!(index < pci->num_ib_windows))
+		return -ENOSPC;
+
 	if ((limit_addr & ~pci->region_limit) != (pci_addr & ~pci->region_limit) ||
 	    !IS_ALIGNED(parent_bus_addr, pci->region_align) ||
 	    !IS_ALIGNED(pci_addr, pci->region_align) || !size) {
-- 
2.52.0