[PATCH 3/3] PCI: dwc: ep: Improve alignment check in dw_pcie_prog_ep_inbound_atu()

[Niklas Cassel <cassel@kernel.org>]

dw_pcie_prog_ep_inbound_atu() is used to program an inbound iATU in
"BAR Match Mode".

While a memory address returned by kmalloc() is guaranteed to be naturally
aligned (aligned to the size of the allocation), it is not guaranteed that
the address that is supplied to pci_epc_set_bar() (and thus the addres that
is supplied to dw_pcie_prog_ep_inbound_atu()) is naturally aligned.

See the register description for IATU_LWR_TARGET_ADDR_OFF_INBOUND_i,
specifically fields LWR_TARGET_RW and LWR_TARGET_HW in the DWC Databook.

"Field size depends on log2(BAR_MASK+1) in BAR match mode."

I.e. only the upper bits are writable, and the number of writable bits is
dependent on the configured BAR_MASK.

Add a check to ensure that the physical address programmed in the iATU is
aligned to the size of the BAR (BAR_MASK+1), as without this, we can get
hard to debug errors, as we could write to bits that are read-only (without
getting a write error), which could cause the iATU to end up redirecting to
a physical address that is different from the address that we intended.

Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/controller/dwc/pcie-designware-ep.c | 8 +++++---
 drivers/pci/controller/dwc/pcie-designware.c    | 5 +++--
 drivers/pci/controller/dwc/pcie-designware.h    | 2 +-
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 507e40bd18c8f..4ad6ebd2ea320 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -128,7 +128,8 @@ static int dw_pcie_ep_write_header(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 }
 
 static int dw_pcie_ep_inbound_atu(struct dw_pcie_ep *ep, u8 func_no, int type,
-				  dma_addr_t cpu_addr, enum pci_barno bar)
+				  dma_addr_t cpu_addr, enum pci_barno bar,
+				  size_t size)
 {
 	int ret;
 	u32 free_win;
@@ -145,7 +146,7 @@ static int dw_pcie_ep_inbound_atu(struct dw_pcie_ep *ep, u8 func_no, int type,
 	}
 
 	ret = dw_pcie_prog_ep_inbound_atu(pci, func_no, free_win, type,
-					  cpu_addr, bar);
+					  cpu_addr, bar, size);
 	if (ret < 0) {
 		dev_err(pci->dev, "Failed to program IB window\n");
 		return ret;
@@ -229,7 +230,8 @@ static int dw_pcie_ep_set_bar(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
 	else
 		type = PCIE_ATU_TYPE_IO;
 
-	ret = dw_pcie_ep_inbound_atu(ep, func_no, type, epf_bar->phys_addr, bar);
+	ret = dw_pcie_ep_inbound_atu(ep, func_no, type, epf_bar->phys_addr, bar,
+				     size);
 	if (ret)
 		return ret;
 
diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 6d6cbc8b5b2c6..3c683b6119c39 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -597,11 +597,12 @@ int dw_pcie_prog_inbound_atu(struct dw_pcie *pci, int index, int type,
 }
 
 int dw_pcie_prog_ep_inbound_atu(struct dw_pcie *pci, u8 func_no, int index,
-				int type, u64 cpu_addr, u8 bar)
+				int type, u64 cpu_addr, u8 bar, size_t size)
 {
 	u32 retries, val;
 
-	if (!IS_ALIGNED(cpu_addr, pci->region_align))
+	if (!IS_ALIGNED(cpu_addr, pci->region_align) ||
+	    !IS_ALIGNED(cpu_addr, size))
 		return -EINVAL;
 
 	dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_LOWER_TARGET,
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 347ab74ac35aa..fc08727116725 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -491,7 +491,7 @@ int dw_pcie_prog_outbound_atu(struct dw_pcie *pci,
 int dw_pcie_prog_inbound_atu(struct dw_pcie *pci, int index, int type,
 			     u64 cpu_addr, u64 pci_addr, u64 size);
 int dw_pcie_prog_ep_inbound_atu(struct dw_pcie *pci, u8 func_no, int index,
-				int type, u64 cpu_addr, u8 bar);
+				int type, u64 cpu_addr, u8 bar, size_t size);
 void dw_pcie_disable_atu(struct dw_pcie *pci, u32 dir, int index);
 void dw_pcie_setup(struct dw_pcie *pci);
 void dw_pcie_iatu_detect(struct dw_pcie *pci);
-- 
2.47.0