[U-Boot] [PATCH 1/4] sunxi: Make FEL mode usable again

[Simon Glass]

Hi,

On 30 January 2015 at 04:58, Siarhei Siamashka
<siarhei.siamashka at gmail.com> wrote:
> The commit f630974ccb3ce93e9607a3354e9acb266a8b7e95
> 'sunxi: Move SPL s_init() code to board_init_f()'
> broke the FEL boot mode.
>
> This patch moves the DRAM initialization back to s_init() and
> introduces an assembly entry point for FEL in order to provide
> guaranteed initialization of the gdata pointer (r9). The assembly
> entry point is also needed to ensure that the SPL code starts
> executing in ARM mode.
>
> Because the sunxi board_init_f() does not contain anything that
> is not already done by the default board_init_f(), it is removed
> too.
>
> Signed-off-by: Siarhei Siamashka <siarhei.siamashka at gmail.com>
> ---
>  arch/arm/cpu/armv7/sunxi/Makefile           |  1 +
>  arch/arm/cpu/armv7/sunxi/board.c            | 26 ++++++++++----------------
>  arch/arm/cpu/armv7/sunxi/start_fel.S        | 16 ++++++++++++++++
>  arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds |  3 ++-
>  4 files changed, 29 insertions(+), 17 deletions(-)
>  create mode 100644 arch/arm/cpu/armv7/sunxi/start_fel.S
>
> diff --git a/arch/arm/cpu/armv7/sunxi/Makefile b/arch/arm/cpu/armv7/sunxi/Makefile
> index 48db744..e0d413d 100644
> --- a/arch/arm/cpu/armv7/sunxi/Makefile
> +++ b/arch/arm/cpu/armv7/sunxi/Makefile
> @@ -40,5 +40,6 @@ obj-$(CONFIG_MACH_SUN7I)      += dram_sun4i.o
>  obj-$(CONFIG_MACH_SUN8I)       += dram_sun8i.o
>  ifdef CONFIG_SPL_FEL
>  obj-y  += start.o
> +extra-y        += start_fel.o
>  endif
>  endif
> diff --git a/arch/arm/cpu/armv7/sunxi/board.c b/arch/arm/cpu/armv7/sunxi/board.c
> index 6e28bcd..ea6cb60 100644
> --- a/arch/arm/cpu/armv7/sunxi/board.c
> +++ b/arch/arm/cpu/armv7/sunxi/board.c
> @@ -85,6 +85,16 @@ void s_init(void)
>         timer_init();
>         gpio_init();
>         i2c_init_board();
> +
> +#ifdef CONFIG_SPL_BUILD
> +       preloader_console_init();

s_init() is called before we have global_data, so you can't use a console.

> +
> +#ifdef CONFIG_SPL_I2C_SUPPORT
> +       /* Needed early by sunxi_board_init if PMU is enabled */
> +       i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);
> +#endif
> +       sunxi_board_init();
> +#endif

Why do you need this code here? Can it not go in board_init_f()?

>  }
>
>  #ifdef CONFIG_SPL_BUILD
> @@ -103,22 +113,6 @@ u32 spl_boot_mode(void)
>  {
>         return MMCSD_MODE_RAW;
>  }
> -
> -void board_init_f(ulong dummy)
> -{
> -       preloader_console_init();
> -
> -#ifdef CONFIG_SPL_I2C_SUPPORT
> -       /* Needed early by sunxi_board_init if PMU is enabled */
> -       i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);
> -#endif
> -       sunxi_board_init();
> -
> -       /* Clear the BSS. */
> -       memset(__bss_start, 0, __bss_end - __bss_start);
> -
> -       board_init_r(NULL, 0);
> -}
>  #endif
>
>  void reset_cpu(ulong addr)
> diff --git a/arch/arm/cpu/armv7/sunxi/start_fel.S b/arch/arm/cpu/armv7/sunxi/start_fel.S
> new file mode 100644
> index 0000000..e1c7cd4
> --- /dev/null
> +++ b/arch/arm/cpu/armv7/sunxi/start_fel.S
> @@ -0,0 +1,16 @@
> +/*
> + * Entry point of the FEL mode SPL.
> + *
> + * Copyright (c) 2015 Siarhei Siamashka <siarhei.siamashka at gmail.com>
> + *
> + * SPDX-License-Identifier:    GPL-2.0+
> + */
> +
> +#include <asm-offsets.h>
> +#include <config.h>
> +#include <linux/linkage.h>
> +
> +ENTRY(_start_fel)
> +       ldr     r9, =gdata
> +       b       s_init

No we don't want global data here, and need to get rid of gdata so we
can use driver model, etc.

> +ENDPROC(_start_fel)
> diff --git a/arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds b/arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds
> index 928b7c1..beb8900 100644
> --- a/arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds
> +++ b/arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds
> @@ -6,7 +6,7 @@
>   */
>  OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
>  OUTPUT_ARCH(arm)
> -ENTRY(s_init)
> +ENTRY(_start_fel)
>  SECTIONS
>  {
>         . = 0x00002000;
> @@ -14,6 +14,7 @@ SECTIONS
>         . = ALIGN(4);
>         .text :
>         {
> +               arch/arm/cpu/armv7/sunxi/start_fel.o    (.text)
>                 *(.text.s_init)

Why does this have to jump to a special s_init? Can it not just start
SPL normally as it does on Tegra, Exynos, etc?

>                 *(.text*)
>         }

There has to be a better way of making this work. Also do you have
instructions on how I can try this out on a pcduino3 or other low-cost
board?

I understand that we need to fix this, but other archs deal with this
within the existing framework, so I'd really like to get sunxi into
the same state.

Regards,
Simon