[U-Boot] [PATCH 2/5] arm: Allow reset init to be controlled

[Simon Glass]

Hi Albert,

On 4 February 2015 at 01:50, Albert ARIBAUD <albert.u.boot at aribaud.net> wrote:
> Hello Simon,
>
> On Tue,  3 Feb 2015 21:18:51 -0700, Simon Glass <sjg at chromium.org>
> wrote:
>> Some boards want to skip the normal reset init. For example OMAP4 SPL
>> does not want to touch VBAR and many boards don't want to set up
>> CP15.
>>
>> Provide a return value from save_boot_params() which allows the board
>> to indicate what reset processing should be done.
>
> Does this have to be at run-time? I'd rather it were a build-time
> config option.

For sunxi, my objective is to remove the special-case FEL code.

Unfortunately when running in FEL mode it does not work if this init
is done. I would ideally like to have SPL determine what mode it is
running in, and work in each case (i.e. not hang). Yes we could make
this a compile-time option, but only at the expense of having two
different SPLs, one for FEL and one for everything else. See Hans'
work on trying to unify these also.

>
>> Signed-off-by: Simon Glass <sjg at chromium.org>
>> ---
>>
>>  arch/arm/cpu/armv7/exynos/spl_boot.c |  5 ++++-
>>  arch/arm/cpu/armv7/start.S           | 11 ++++++++---
>>  arch/arm/include/asm/system.h        | 15 +++++++++++++++
>>  3 files changed, 27 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/arm/cpu/armv7/exynos/spl_boot.c b/arch/arm/cpu/armv7/exynos/spl_boot.c
>> index bc237c9..6e249f1 100644
>> --- a/arch/arm/cpu/armv7/exynos/spl_boot.c
>> +++ b/arch/arm/cpu/armv7/exynos/spl_boot.c
>> @@ -309,4 +309,7 @@ void board_init_r(gd_t *id, ulong dest_addr)
>>       while (1)
>>               ;
>>  }
>> -void save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3) {}
>> +u32 save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3)
>> +{
>> +     return 0;
>> +}
>> diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
>> index c5f94ef..0ba26f7 100644
>> --- a/arch/arm/cpu/armv7/start.S
>> +++ b/arch/arm/cpu/armv7/start.S
>> @@ -52,6 +52,9 @@ reset:
>>   * Continue to use ROM code vector only in OMAP4 spl)
>>   */
>>  #if !(defined(CONFIG_OMAP44XX) && defined(CONFIG_SPL_BUILD))
>> +     teq     r0, #RESET_SKIP_VBVAR
>> +     bne     vbar_done
>> +
>>       /* Set V=0 in CP15 SCTLR register - for VBAR to point to vector */
>>       mrc     p15, 0, r2, c1, c0, 0   @ Read CP15 SCTLR Register
>>       bic     r2, #CR_V               @ V = 0
>> @@ -61,10 +64,11 @@ reset:
>>       ldr     r2, =_start
>>       mcr     p15, 0, r2, c12, c0, 0  @Set VBAR
>>  #endif
>> -
>> +vbar_done:
>>       /* the mask ROM code should have PLL and others stable */
>>  #ifndef CONFIG_SKIP_LOWLEVEL_INIT
>> -     bl      cpu_init_cp15
>> +     teq     r0, #RESET_SKIP_CP15
>> +     bleq    cpu_init_cp15
>>       bl      cpu_init_crit
>>  #endif
>>
>> @@ -88,11 +92,12 @@ ENDPROC(c_runtime_cpu_setup)
>>
>>  /*************************************************************************
>>   *
>> - * void save_boot_params(u32 r2, u32 r1, u32 r2, u32 r3)
>> + * u32 save_boot_params(u32 r2, u32 r1, u32 r2, u32 r3)
>>   *   __attribute__((weak));
>>   *
>>   * Stack pointer is not yet initialized at this moment
>>   * Don't save anything to stack even if compiled with -O0
>> + * Return flags - see RESET_... in system.h
>>   *
>>   *************************************************************************/
>>  ENTRY(save_boot_params)
>> diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
>> index 89f2294..98e49a7 100644
>> --- a/arch/arm/include/asm/system.h
>> +++ b/arch/arm/include/asm/system.h
>> @@ -140,8 +140,23 @@ void flush_l3_cache(void);
>>   */
>>  #define __asmeq(x, y)  ".ifnc " x "," y " ; .err ; .endif\n\t"
>>
>> +/* Control bits for reset processing */
>> +#define RESET_SKIP_VBVAR     (1 << 0)        /* Skip vector address setup */
>> +#define RESET_SKIP_CP15              (1 << 1)        /* Skip CP15 setup */
>> +
>>  #ifndef __ASSEMBLY__
>>
>> +/**
>> + * save_boot_params() - Save boot parameters before starting reset sequence
>> + *
>> + * @r0:              Value of r0
>> + * @r1:              Value of r1
>> + * @r2:              Value of r2
>> + * @r3:              Value of r3
>> + * @return reset flags (see RESET_... above)
>> + */
>> +u32 save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3);
>> +
>>  #define isb() __asm__ __volatile__ ("" : : : "memory")
>>
>>  #define nop() __asm__ __volatile__("mov\tr0,r0\t@ nop\n\t");
>> --
>> 2.2.0.rc0.207.ga3a616c

Regards,
Simon