[U-Boot] [PATCH 2/2] ARM: bcm283x: Implement EFI RTS reset_system

[Simon Glass]

Hi Alexander,


On 5 June 2016 at 15:17, Alexander Graf <agraf at suse.de> wrote:
> The rpi has a pretty simple way of resetting the whole system. All it takes
> is to poke a few registers at a well defined location in MMIO space.
>
> This patch adds support for the EFI loader implementation to allow an OS to
> reset and power off the system when we're outside of boot time.
>
> Signed-off-by: Alexander Graf <agraf at suse.de>
> ---
>  arch/arm/mach-bcm283x/include/mach/wdog.h |  2 +-
>  arch/arm/mach-bcm283x/reset.c             | 59 +++++++++++++++++++++++++++----
>  2 files changed, 54 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm/mach-bcm283x/include/mach/wdog.h b/arch/arm/mach-bcm283x/include/mach/wdog.h
> index 7741d7b..b4caca1 100644
> --- a/arch/arm/mach-bcm283x/include/mach/wdog.h
> +++ b/arch/arm/mach-bcm283x/include/mach/wdog.h
> @@ -16,7 +16,7 @@
>  struct bcm2835_wdog_regs {
>         u32 unknown0[7];
>         u32 rstc;
> -       u32 unknown1;
> +       u32 rsts;
>         u32 wdog;
>  };
>
> diff --git a/arch/arm/mach-bcm283x/reset.c b/arch/arm/mach-bcm283x/reset.c
> index 72cdc31..e87241d 100644
> --- a/arch/arm/mach-bcm283x/reset.c
> +++ b/arch/arm/mach-bcm283x/reset.c
> @@ -10,19 +10,66 @@
>  #include <common.h>
>  #include <asm/io.h>
>  #include <asm/arch/wdog.h>
> +#include <efi_loader.h>
>
>  #define RESET_TIMEOUT 10
>
> -void reset_cpu(ulong addr)
> +/*
> + * The Raspberry Pi firmware uses the RSTS register to know which partiton
> + * to boot from. The partiton value is spread into bits 0, 2, 4, 6, 8, 10.
> + * Partiton 63 is a special partition used by the firmware to indicate halt.
> + */
> +#define BCM2835_WDOG_RSTS_RASPBERRYPI_HALT     0x555
> +
> +EFI_RUNTIME_DATA struct bcm2835_wdog_regs *wdog_regs =
> +       (struct bcm2835_wdog_regs *)BCM2835_WDOG_PHYSADDR;
> +
> +void EFI_RUNTIME_TEXT reset_cpu(ulong addr)
>  {
> -       struct bcm2835_wdog_regs *regs =
> -               (struct bcm2835_wdog_regs *)BCM2835_WDOG_PHYSADDR;
>         uint32_t rstc;
>
> -       rstc = readl(&regs->rstc);
> +       rstc = readl(&wdog_regs->rstc);
>         rstc &= ~BCM2835_WDOG_RSTC_WRCFG_MASK;
>         rstc |= BCM2835_WDOG_RSTC_WRCFG_FULL_RESET;
>
> -       writel(BCM2835_WDOG_PASSWORD | RESET_TIMEOUT, &regs->wdog);
> -       writel(BCM2835_WDOG_PASSWORD | rstc, &regs->rstc);
> +       writel(BCM2835_WDOG_PASSWORD | RESET_TIMEOUT, &wdog_regs->wdog);
> +       writel(BCM2835_WDOG_PASSWORD | rstc, &wdog_regs->rstc);

This is rpi-specific code, and presumably U-Boot itself would want to
provide this reset facility.

But this code is marked with EFI_RUNTIME_TEXT. I think this means that
it can still be called as a normal U-Boot function, right?

Is there some enforcement at link-time that all the function called by
EFI_RUNTIME_TEXT functions are also EFI_RUNTIME_TEXT?

Also I'd like to suggest a better name. How about __efi_runtime
instead of EFI_RUNTIME_TEXT? All those capital letters in function
declarations will give me a headache...we use __packed, __weak, etc.

> +}
> +
> +#ifdef CONFIG_EFI_LOADER
> +
> +void EFI_RUNTIME_TEXT EFIAPI efi_reset_system(
> +                       enum efi_reset_type reset_type,
> +                       efi_status_t reset_status,
> +                       unsigned long data_size, void *reset_data)
> +{
> +       u32 val;
> +
> +       switch (reset_type) {
> +       case EFI_RESET_COLD:
> +       case EFI_RESET_WARM:
> +               reset_cpu(0);
> +               break;
> +       case EFI_RESET_SHUTDOWN:
> +               /*
> +                * We set the watchdog hard reset bit here to distinguish this reset
> +                * from the normal (full) reset. bootcode.bin will not reboot after a
> +                * hard reset.
> +                */
> +               val = readl(&wdog_regs->rsts);
> +               val |= BCM2835_WDOG_PASSWORD;
> +               val |= BCM2835_WDOG_RSTS_RASPBERRYPI_HALT;
> +               writel(val, &wdog_regs->rsts);
> +               reset_cpu(0);
> +               break;
> +       }
> +
> +       while (1) { }
>  }
> +
> +void efi_reset_system_init(void)
> +{
> +       efi_add_runtime_mmio(&wdog_regs, sizeof(*wdog_regs));
> +}
> +
> +#endif
> --
> 1.8.5.6
>

Regards,
Simon