PCI: dwc: Simplify in/outbound iATU setup methods

Previously __dw_pcie_prog_outbound_atu() duplicated a lot of code between
the iatu_unroll_enabled version and the PCIE_ATU_VIEWPORT version:

__dw_pcie_prog_outbound_atu
if (iatu_unroll_enabled)
dw_pcie_prog_outbound_atu_unroll
dw_pcie_writel_ob_unroll(PCIE_ATU_UNR_LOWER_BASE, ...)
dw_pcie_writel_ob_unroll(PCIE_ATU_UNR_UPPER_BASE, ...)
...
return
dw_pcie_writel_dbi(PCIE_ATU_VIEWPORT, ...)
dw_pcie_writel_dbi(PCIE_ATU_LOWER_BASE, ...)
dw_pcie_writel_dbi(PCIE_ATU_UPPER_BASE, ...)
...

Unify those by pushing the unroll address computation and viewport
selection down into dw_pcie_writel_atu() so we can use the same
dw_pcie_writel_atu_ob() accessor for both paths:

__dw_pcie_prog_outbound_atu
dw_pcie_writel_atu_ob(PCIE_ATU_LOWER_BASE, ...)
dw_pcie_writel_atu
dw_pcie_select_atu # new
if (iatu_unroll_enabled)
return pci->atu_base + PCIE_ATU_UNROLL_BASE(...)
dw_pcie_writel_dbi(PCIE_ATU_VIEWPORT, ...)
return pci->atu_base
dw_pcie_write(base + reg)
dw_pcie_writel_atu_ob(PCIE_ATU_UPPER_BASE, ...)
...

In the non-unroll case, this does involve more MMIO writes to
PCIE_ATU_VIEWPORT, but it's mainly in initialization paths and the code
simplification is significant.

[bhelgaas: commit log, simplify dw_pcie_select_atu()]
Link: https://lore.kernel.org/r/20220624143947.8991-12-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI: tegra194: Fix MCFG quirk build regressions

7f100744749e ("PCI: tegra: Add Tegra194 MCFG quirks for ECAM errata")
caused a few build regressions:

- 7f100744749e removed the Makefile rule for CONFIG_PCIE_TEGRA194, so
pcie-tegra.c can no longer be built as a module. Restore that rule.

- 7f100744749e added "#ifdef CONFIG_PCIE_TEGRA194" around the native
driver, but that's only set when the driver is built-in (for a module,
CONFIG_PCIE_TEGRA194_MODULE is defined).

The ACPI quirk is completely independent of the rest of the native
driver, so move the quirk to its own file and remove the #ifdef in the
native driver.

- 7f100744749e added symbols that are always defined but used only when
CONFIG_PCIEASPM, which causes warnings when CONFIG_PCIEASPM is not set:

drivers/pci/controller/dwc/pcie-tegra194.c:259:18: warning: ‘event_cntr_data_offset’ defined but not used [-Wunused-const-variable=]
drivers/pci/controller/dwc/pcie-tegra194.c:250:18: warning: ‘event_cntr_ctrl_offset’ defined but not used [-Wunused-const-variable=]
drivers/pci/controller/dwc/pcie-tegra194.c:243:27: warning: ‘pcie_gen_freq’ defined but not used [-Wunused-const-variable=]

Fixes: 7f100744749e ("PCI: tegra: Add Tegra194 MCFG quirks for ECAM errata")
Link: https://lore.kernel.org/r/20210610064134.336781-1-jonathanh@nvidia.com
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>