soc/mediatek: Add PCIe support

Add PCIe support for MediaTek platform.

Reference:
  - MT8195 Register Map V0.3-2, Chapter 3.18 PCIe controller (Page 1250)
  - linux/drivers/pci/controller/pcie-mediatek-gen3.c

This code is based on MT8195 platform, but it should be common in each
platform with the same PCIe IP in the future.

TEST=Build pass and boot up to kernel successfully via SSD on Dojo
board, here is the SSD information in boot log:
 == NVME IDENTIFY CONTROLLER DATA ==
    PCI VID   : 0x15b7
    PCI SSVID : 0x15b7
    SN        : 21517J440114
    MN        : WDC PC SN530 SDBPTPZ-256G-1006
    RAB       : 0x4
    AERL      : 0x7
    SQES      : 0x66
    CQES      : 0x44
    NN        : 0x1
Identified NVMe model WDC PC SN530 SDBPTPZ-256G-1006

BUG=b:178565024

Signed-off-by: Jianjun Wang <jianjun.wang@mediatek.com>
Change-Id: Ib9b6adaafa20aeee136372ec9564273f86776da0
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56791
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>

0 files changed, 0 insertions, 0 deletions