[Skiboot] [PATCH 2/2] xscom: Parse P10 ec revision

[Dan Horák]

On Thu, 12 May 2022 13:59:38 +0930
Joel Stanley <joel at jms.id.au> wrote:

> Use a look up table to support the p9, p10dd1 and p10dd2 conversions.
> 
> Running on a Rainier:
> 
> > [  268.267370706,6] CPU: P10 generation processor (max 4 threads/core)
> > [  268.267372501,7] CPU: Boot CPU PIR is 0x0460 PVR is 0x00801200
> 
> > [  268.284420384,5] CHIP: Chip ID 0000 type: P10 DD2.02
> > [  268.284464084,5] CHIP: Chip ID 0002 type: P10 DD2.02
> > [  268.284500468,5] CHIP: Chip ID 0004 type: P10 DD2.02
> > [  268.284538166,5] CHIP: Chip ID 0006 type: P10 DD2.02
> > [  268.286317879,5] PLAT: Detected Rainier platform
> 
> Signed-off-by: Joel Stanley <joel at jms.id.au>
> ---
>  hw/xscom.c | 37 +++++++++++++++++++------------------
>  1 file changed, 19 insertions(+), 18 deletions(-)
> 
> diff --git a/hw/xscom.c b/hw/xscom.c
> index 862bd36ab75d..e40d69336ea6 100644
> --- a/hw/xscom.c
> +++ b/hw/xscom.c
> @@ -841,41 +841,42 @@ int64_t xscom_read_cfam_chipid(uint32_t partid, uint32_t *chip_id)
>  	return rc;
>  }
>  
> +/* The recipe comes from the p10_getecid hardware procedure */
>  static uint8_t xscom_get_ec_rev(struct proc_chip *chip)
>  {
>  	uint64_t ecid2 = 0;
> -	uint8_t rev;
> +	int8_t rev;
> +	const int8_t *table;
> +	/*                             0   1   2   3   4   5   6   7 */
> +	const int8_t p9table[8] =     {0,  1, -1,  2, -1, -1, -1,  3};
> +	const int8_t p10dd1table[8] = {0,  1,  2,  3, -1, -1,  4, -1};
> +	const int8_t p10dd2table[8] = {0,  2,  3,  4, -1, -1,  5, -1};
>  
>  	if (chip_quirk(QUIRK_MAMBO_CALLOUTS))
>  		return 0;
>  
>  	switch (proc_gen) {
>  	case proc_gen_p9:
> +		table = p9table;
> +		break;
> +	case proc_gen_p10:
> +		if (chip->ec_level < 0x20)
> +			table = p10dd1table;
> +		else
> +			table = p10dd2table;
>  		break;
>  	default:
>  		return 0;
>  	}
>  
>  	xscom_read(chip->id, 0x18002, &ecid2);
> -	switch((ecid2 >> 45) & 7) {
> -	case 0:
> -		rev = 0;
> -		break;
> -	case 1:
> -		rev = 1;
> -		break;
> -	case 3:
> -		rev = 2;
> -		break;
> -	case 7:
> -		rev = 3;
> -		break;
> -	default:
> -		rev = 0;
> -	}
> +
> +	rev = table[ecid2 >> 45 & 7];

personally I would prefer the parens there as used in the original
code, looks better readable to me


		Dan

> +	if (rev < 0)
> +		return 0;
>  
>  	prlog(PR_INFO,"P%d DD%i.%i%d detected\n",
> -			9,
> +			proc_gen == proc_gen_p9 ? 9 : 10,
>  			0xf & (chip->ec_level >> 4),
>  			chip->ec_level & 0xf,
>  			rev);
> -- 
> 2.35.1
> 
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