[Skiboot] [PATCH v3 6/6] platform: Identify correct bmc platform based on bmc hw version

[Nicholas Piggin]

On Thu Feb 6, 2025 at 11:56 PM AEST, Mahesh Salgaonkar wrote:
> At the moment the generic platform sets bmc_generic() as bmc platform
> which does not have any support to initialize the flash and hence it
> fails to load petitboot kernel.
>
> [  583.105000325,4] FLASH: Failed to load VERSION data
> [  583.105490257,5] INIT: Waiting for kernel...
> [  583.105523156,5] INIT: platform wait for kernel load failed
> [  583.105555219,5] INIT: Assuming kernel at 0x20000000
> [  583.105589925,3] INIT: ELF header not found. Assuming raw binary.
> [...]
> [  583.299682673,5] INIT: Starting kernel at 0x20000000, fdt at 0x30a44eb0
> 1274673 bytes
> [  583.344432417,3] ***********************************************
> [  583.344490230,3] Fatal Exception 0x800 at 0000000020000000
> MSR 9000000000000000
> [  583.344535875,3] CFAR : 0000000030022948 MSR  : 9000000000000000
> [  583.344578019,3] SRR0 : 0000000020000000 SRR1 : 9000000000000000
> [  583.344620242,3] HSRR0: 0000000020000000 HSRR1: 9000000000000000
>
> OPAL builds the device tree for BMC based system using HDAT. It
> populates bmc/compatible node with bmc hw version e.g.
> "ibm,ast2600,openbmc". Use that to identify proper BMC hw board and
> initialize BMC platform with proper backend. This allows opal to
> successfully load and boot into petitboot kernel.

Interesting hack. So you need this because there no real platform
for P11 yet? I'd almost rather rip the generic stuff out entirely, it
looks like you'll miss the power down and some other things for
example.

If you're finding it useful for now then okay, but would be nice to
have a platform for it.

Reviewed-by: Nicholas Piggin <npiggin at gmail.com>

>
> Signed-off-by: Mahesh Salgaonkar <mahesh at linux.ibm.com>
> ---
>  core/platform.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/core/platform.c b/core/platform.c
> index 320fdea03d..34ef5e5d7b 100644
> --- a/core/platform.c
> +++ b/core/platform.c
> @@ -135,15 +135,27 @@ static int64_t opal_cec_reboot2(uint32_t reboot_type, char *diag)
>  }
>  opal_call(OPAL_CEC_REBOOT2, opal_cec_reboot2, 2);
>  
> +static void generic_platform_fixup_bmc(struct dt_node *bmc)
> +{
> +	/* Try setting proper bmc platform by checking compatible property */
> +	if (dt_node_is_compatible(bmc, "ibm,ast2600,openbmc"))
> +		platform.bmc = &bmc_plat_ast2600_openbmc;
> +}
> +
>  static bool generic_platform_probe(void)
>  {
> -	if (dt_find_by_path(dt_root, "bmc")) {
> +	struct dt_node *bmc;
> +
> +	bmc = dt_find_by_path(dt_root, "bmc");
> +	if (bmc) {
>  		/* We appear to have a BMC... so let's cross our fingers
>  		 * and see if we can do anything!
>  		 */
>  		prlog(PR_ERR, "GENERIC BMC PLATFORM: **GUESSING** that there's "
>  		      "*maybe* a BMC we can talk to.\n");
>  		prlog(PR_ERR, "THIS IS ****UNSUPPORTED****, BRINGUP USE ONLY.\n");
> +
> +		generic_platform_fixup_bmc(bmc);
>  		astbmc_early_init();
>  	} else {
>  		uart_init();