PCI: dwc: ep: Add 'address' alignment to 'size' check in dw_pcie_prog_ep_inbound_atu()

PCI: dwc: ep: Add 'address' alignment to 'size' check in dw_pcie_prog_ep_inbound_atu()

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

A memory address returned by e.g. kmalloc() is guaranteed to have natural
alignment (aligned to the size of the allocation). It is however not
guaranteed that pci_epc_set_bar() (and thus dw_pcie_prog_ep_inbound_atu())
is supplied an address that has natural alignment. (An EPF driver can send
in an arbitrary physical address to pci_epc_set_bar().)

The DWC Databook description for the LWR_TARGET_RW and LWR_TARGET_HW fields
in the IATU_LWR_TARGET_ADDR_OFF_INBOUND_i registers state that:
"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.

Link: https://lore.kernel.org/r/20241213143301.4158431-11-cassel@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>