[U-Boot] [RFC v1 PATCH 1/1] mpc85xx: Enable pre-relocation malloc for MPC85xx

[York Sun <york.sun@nxp.com>]

On 03/29/2016 11:53 PM, Mario Six wrote:
> To enable DM on MPC85xx, we need pre-relocation malloc, which is
> implemented in this patch.
> 
> Signed-off-by: Mario Six <mario.six@gdsys.cc>
> Cc: York Sun <york.sun@nxp.com>
> Cc: Simon Glass <sjg@chromium.org>
> ---
>  arch/powerpc/cpu/mpc85xx/cpu_init_early.c |  8 --------
>  arch/powerpc/cpu/mpc85xx/start.S          | 28 ++++++++++++++++++++++++++++
>  2 files changed, 28 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/powerpc/cpu/mpc85xx/cpu_init_early.c b/arch/powerpc/cpu/mpc85xx/cpu_init_early.c
> index 235a635..e6e1688 100644
> --- a/arch/powerpc/cpu/mpc85xx/cpu_init_early.c
> +++ b/arch/powerpc/cpu/mpc85xx/cpu_init_early.c
> @@ -82,7 +82,6 @@ void setup_ifc(void)
>  void cpu_init_early_f(void *fdt)
>  {
>  	u32 mas0, mas1, mas2, mas3, mas7;
> -	int i;
>  #ifdef CONFIG_SYS_FSL_ERRATUM_P1010_A003549
>  	ccsr_gur_t *gur = (void *)(CONFIG_SYS_MPC85xx_GUTS_ADDR);
>  #endif
> @@ -95,13 +94,6 @@ void cpu_init_early_f(void *fdt)
>  	/* Pointer is writable since we allocated a register for it */
>  	gd = (gd_t *) (CONFIG_SYS_INIT_RAM_ADDR + CONFIG_SYS_GBL_DATA_OFFSET);
> 
> -	/*
> -	 * Clear initial global data
> -	 *   we don't use memset so we can share this code with NAND_SPL
> -	 */
> -	for (i = 0; i < sizeof(gd_t); i++)
> -		((char *)gd)[i] = 0;
> -
>  #ifdef CONFIG_QEMU_E500
>  	/*
>  	 * CONFIG_SYS_CCSRBAR_PHYS below may use gd->fdt_blob on ePAPR systems,
> diff --git a/arch/powerpc/cpu/mpc85xx/start.S b/arch/powerpc/cpu/mpc85xx/start.S
> index d867e2a..e6b5203 100644
> --- a/arch/powerpc/cpu/mpc85xx/start.S
> +++ b/arch/powerpc/cpu/mpc85xx/start.S
> @@ -1152,6 +1152,34 @@ _start_cont:
>  	/* Setup the stack in initial RAM,could be L2-as-SRAM or L1 dcache*/
>  	lis	r3,(CONFIG_SYS_INIT_RAM_ADDR)@h
>  	ori	r3,r3,((CONFIG_SYS_INIT_SP_OFFSET-16)&~0xf)@l /* Align to 16 */
> +
> +#ifdef CONFIG_SYS_MALLOC_F_LEN
> +	/* Leave 16+ byte for back chain termination and NULL return address */
> +	subi	r3,r3,((CONFIG_SYS_MALLOC_F_LEN+16+15)&~0xf)
> +
> +	/* End of RAM */
> +	lis	r4,(CONFIG_SYS_INIT_RAM_ADDR)@h
> +	ori	r4,r4,(CONFIG_SYS_INIT_RAM_SIZE)@l
> +
> +	li	r0,0
> +
> +1: 	subi 	r4,r4,4
> +	stw 	r0,0(r4)
> +	cmplw 	r4,r3
> +	bne	1b
> +
> +	lis	r4,(CONFIG_SYS_INIT_RAM_ADDR)@h
> +	ori	r4,r4,(CONFIG_SYS_GBL_DATA_OFFSET)@l
> +
> +	addi	r3,r3,16	/* Pre-relocation malloc area */
> +	stw	r3,GD_MALLOC_BASE(r4)
> +	subi	r3,r3,16
> +
> +	/* Fix issue with exception handler alignment */
> +	nop
> +	nop
> +	nop

Why do you need this? Does the code get too long and enters exception handler space?

> +#endif
>  	li	r0,0
>  	stw	r0,0(r3)	/* Terminate Back Chain */
>  	stw	r0,+4(r3)	/* NULL return address. */
> --

This patch presumes stack is right under GD, which is OK. But
CONFIG_SYS_MALLOC_F_LEN has not been used by powerpc. Presumption of
(CONFIG_SYS_MALLOC_F_LEN + GENERATED_GBL_DATA_SIZE) < CONFIG_SYS_INIT_RAM_SIZE
may not be true. Would it be better to check@compiling time to make sure we
have enough init ram for the malloc len?

York