Re: [PATCH v3 6/8] cpufreq: sun50i: Add H616 support

[Andre Przywara <andre.przywara@arm.com>]

On Tue, 26 Mar 2024 22:46:27 -0500
Samuel Holland <samuel@sholland.org> wrote:

Hi Samuel,

> On 3/26/24 06:47, Andre Przywara wrote:
> > From: Martin Botka <martin.botka@somainline.org>
> > 
> > The Allwinner H616/H618 SoCs have different OPP tables per SoC version
> > and die revision. The SoC version is stored in NVMEM, as before, though
> > encoded differently. The die revision is in a different register, in the
> > SRAM controller. Firmware already exports that value in a standardised
> > way, through the SMCCC SoCID mechanism. We need both values, as some chips
> > have the same SoC version, but they don't support the same frequencies and
> > they get differentiated by the die revision.
> > 
> > Add the new compatible string and tie the new translation function to
> > it. This mechanism not only covers the original H616 SoC, but also its
> > very close sibling SoCs H618 and H700, so add them to the list as well.
> > 
> > Signed-off-by: Martin Botka <martin.botka@somainline.org>
> > Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> > ---
> >  drivers/cpufreq/sun50i-cpufreq-nvmem.c | 61 ++++++++++++++++++++++++++
> >  1 file changed, 61 insertions(+)
> > 
> > diff --git a/drivers/cpufreq/sun50i-cpufreq-nvmem.c b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > index bd170611c7906..f9e9fc340f848 100644
> > --- a/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > +++ b/drivers/cpufreq/sun50i-cpufreq-nvmem.c
> > @@ -10,6 +10,7 @@
> >  
> >  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> >  
> > +#include <linux/arm-smccc.h>
> >  #include <linux/cpu.h>
> >  #include <linux/module.h>
> >  #include <linux/nvmem-consumer.h>
> > @@ -46,14 +47,71 @@ static u32 sun50i_h6_efuse_xlate(u32 speedbin)
> >  		return 0;
> >  }
> >  
> > +/*
> > + * Judging by the OPP tables in the vendor BSP, the quality order of the
> > + * returned speedbin index is 4 -> 0/2 -> 3 -> 1, from worst to best.
> > + * 0 and 2 seem identical from the OPP tables' point of view.
> > + */
> > +static u32 sun50i_h616_efuse_xlate(u32 speedbin)
> > +{
> > +	int ver_bits = arm_smccc_get_soc_id_revision();  
> 
> This needs a Kconfig dependency on ARM_SMCCC_SOC_ID.

That was my first impulse as well, but it's actually not true:
ARM_SMCCC_SOC_ID just protects the sysfs export code, not this function
here. That does just depend on HAVE_ARM_SMCCC_DISCOVERY, which gets
selected by ARM_GIC_V3, which gets selected by CONFIG_ARM64. So the
arm64 kernel is safe.
Now apart from ARM(32) (where the situation seems a bit more complex) I
just realise that this would torpedo Brandon's D1 efforts, so I need to
add this change I played with to provide an alternative:

static int get_soc_id_revision(void)
{
#ifdef CONFIG_HAVE_ARM_SMCCC_DISCOVERY
	return arm_smccc_get_soc_id_revision();
#else
	/* Return the value for the worse die revision, to be safe. */
	return 2;
#endif
}

Does that look acceptable, despite the #ifdef?

Cheers,
Andre


> 
> Regards,
> Samuel
> 
> > +	u32 value = 0;
> > +
> > +	switch (speedbin & 0xffff) {
> > +	case 0x2000:
> > +		value = 0;
> > +		break;
> > +	case 0x2400:
> > +	case 0x7400:
> > +	case 0x2c00:
> > +	case 0x7c00:
> > +		if (ver_bits != SMCCC_RET_NOT_SUPPORTED &&
> > ver_bits <= 1) {
> > +			/* ic version A/B */
> > +			value = 1;
> > +		} else {
> > +			/* ic version C and later version */
> > +			value = 2;
> > +		}
> > +		break;
> > +	case 0x5000:
> > +	case 0x5400:
> > +	case 0x6000:
> > +		value = 3;
> > +		break;
> > +	case 0x5c00:
> > +		value = 4;
> > +		break;
> > +	case 0x5d00:
> > +		value = 0;
> > +		break;
> > +	case 0x6c00:
> > +		value = 5;
> > +		break;
> > +	default:
> > +		pr_warn("sun50i-cpufreq-nvmem: unknown speed bin
> > 0x%x, using default bin 0\n",
> > +			speedbin & 0xffff);
> > +		value = 0;
> > +		break;
> > +	}
> > +
> > +	return value;
> > +}
> > +
> >  static struct sunxi_cpufreq_data sun50i_h6_cpufreq_data = {
> >  	.efuse_xlate = sun50i_h6_efuse_xlate,
> >  };
> >  
> > +static struct sunxi_cpufreq_data sun50i_h616_cpufreq_data = {
> > +	.efuse_xlate = sun50i_h616_efuse_xlate,
> > +};
> > +
> >  static const struct of_device_id cpu_opp_match_list[] = {
> >  	{ .compatible = "allwinner,sun50i-h6-operating-points",
> >  	  .data = &sun50i_h6_cpufreq_data,
> >  	},
> > +	{ .compatible = "allwinner,sun50i-h616-operating-points",
> > +	  .data = &sun50i_h616_cpufreq_data,
> > +	},
> >  	{}
> >  };
> >  
> > @@ -230,6 +288,9 @@ static struct platform_driver
> > sun50i_cpufreq_driver = { 
> >  static const struct of_device_id sun50i_cpufreq_match_list[] = {
> >  	{ .compatible = "allwinner,sun50i-h6" },
> > +	{ .compatible = "allwinner,sun50i-h616" },
> > +	{ .compatible = "allwinner,sun50i-h618" },
> > +	{ .compatible = "allwinner,sun50i-h700" },
> >  	{}
> >  };
> >  MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list);  
> 
>