[PATCH 2/2] arm: mvebu: turris_omnia: Add support for design with SW reset signals

[Marek Behún]

On Fri, 29 Jul 2022 13:29:07 +0200
Pali Rohár <pali at 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 <pali at kernel.org>

Reviewed-by: Marek Behún <kabel at kernel.org>