[PATCH 0/4] reboot SiFive Unmatched via PMIC

[Bin Meng]

On Fri, Sep 24, 2021 at 7:34 PM Nikita Shubin <nikita.shubin at maquefel.me> wrote:
>
> From: Nikita Shubin <n.shubin at yadro.com>
>
> This series introduce rebooting via i2c PMIC, currently on
> SiFive Unmatched board.
>
> teseted via Linux with reset extension and direct ecall from
> u-boot.
>
> With this it becomes possible to reboot/shutdown the board
> if Linux or u-boot is accompanied with OpenSBI reset extension.
>
> "gpio-poweroff" is required to be removed from u-boot dts file, as
> it overrides fdt_reset_da9063.
>
> fdt_reset_da9063 is loaded if "dlg,da9063" is present in device tree.
>
> Moreover it's look like we require a convenient "sleep" functionality,
> currently i've implemented sleep via CSR_MCYCLE, assuming we don't normally
> communicate with device while operational only on start/shutdown.
>
> ```
> static inline void wait_cycles(unsigned long cycles)
> {
>         csr_write(CSR_MCYCLE, 0);
>         while (cycles > csr_read_num(CSR_MCYCLE));
> }
> ```
>
> The original sequence was discovered by Alexandre Ghiti posted a patch on
> linux-riscv mail-lists.
>
> https://patchwork.kernel.org/project/linux-riscv/patch/20210921053356.1705833-1-alexandre.ghiti@canonical.com/
>
> These magick numbers are readed as:
> - select PAGE0
> - set WAKE_UP bit in CONTROL_A reg
> - mask setting POWER1, POWER domain and STANDBY, and poweroff SYSTEM domain
>
> Nikita Shubin (4):
>   lib: utils/i2c: Add generic I2C configuration library
>   lib: utils/gpio: Add simple FDT based I2C framework
>   lib: utils/gpio: Add minimal SiFive I2C driver
>   lib: utils/reset: Add generic da9063 reset driver
>

It looks like we will end up having lots of reset drivers in OpenSBI
in the future, no surprise, as this is what the spec requires, sigh.

Alexandre Ghiti has posted U-Boot patches to reset Unmatched via PMIC as well.
http://patchwork.ozlabs.org/project/uboot/patch/20210924084231.3311216-5-alexandre.ghiti@canonical.com/

Regards,
Bin