On Fri, 29 Jul 2022 13:29:07 +0200 Pali Rohár <p...@kernel.org> wrote:
> New Turris Omnia HW board revision requires that software controls > peripheral reset signals, namely PERST# signals on mPCIe slots, ethernet > phy reset and lan switch reset. Those pins are connected to MCU controlled > by MCU i2c API as GPIOs. On new HW board revision those pins stay in reset > after board reset and software has to release these peripherals from reset > manually. MCU announce this requirement by FEAT_PERIPH_MCU bit in > CMD_GET_FEATURES command. > > On older HW board revisions when FEAT_PERIPH_MCU is not announced, all > those reset signals are automatically released after board finish reset. > > Detect FEAT_PERIPH_MCU bit in board_fix_fdt() and ft_board_setup() > functions and insert into device tree blob pcie "reset-gpios" and eth phy > "phy-reset-gpios" properties with corresponding MCU gpio definitions. > PCIe and eth PHY drivers then automatically release resets during device > initialization. Both U-Boot and Linux kernel drivers support those device > tree reset properties. > > Initialization of lan switch on new HW board revision is more complicated. > Switch strapping pins are shared with switch RGMII pins. And strapping pins > must be in specific configuration after releasing switch reset. Due to pin > sharing, it is first required to switch A385 side of switch pins into GPIO > mode, set strapping configuration, release switch from reset and after that > switch A385 pins back to RGMII mode. > > Because this complicated setup is not supported by switch DSA drivers and > cannot be expressed easily in device tree, implement it manually in SPL > function spl_board_init(). So in proper U-Boot and OS/kernel would be lan > switch initialized and be in same configuration like it was on old HW board > revisions (where reset sequence did those steps at hardware level). > > Signed-off-by: Pali Rohár <p...@kernel.org> Reviewed-by: Marek Behún <ka...@kernel.org>
