Re: [PATCH v2 3/3] power: domain: Add Apple pmgr driver

Simon Glass
2021-12-29T13:36:58Z

Hi Mark,

On Tue, 28 Dec 2021 at 07:27, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
>
> > From: Simon Glass <sjg@chromium.org>
> > Date: Tue, 28 Dec 2021 01:34:16 -0700
> >
> > Hi Mark,
> >
> > On Thu, 23 Dec 2021 at 14:35, Mark Kettenis <kettenis@openbsd.org> wrote:
> > >
> > > This driver supports power domains for the power management
> > > controller found on Apple SoCs.
> > >
> > > Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
> > > ---
> > > arch/arm/Kconfig | 3 +
> > > drivers/power/domain/Kconfig | 8 +++
> > > drivers/power/domain/Makefile | 1 +
> > > drivers/power/domain/apple-pmgr.c | 113 ++++++++++++++++++++++++++++++
> > > 4 files changed, 125 insertions(+)
> > > create mode 100644 drivers/power/domain/apple-pmgr.c
> >
> > Reviewed-by: Simon Glass <sjg@chromium.org>
> >
> > nits below
> >
> > >
> > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> > > index 59e031de04..40d3f66acb 100644
> > > --- a/arch/arm/Kconfig
> > > +++ b/arch/arm/Kconfig
> > > @@ -938,6 +938,9 @@ config ARCH_APPLE
> > > select OF_BOARD
> > > select PINCTRL
> > > select POSITION_INDEPENDENT
> > > + select POWER_DOMAIN
> > > + select REGMAP
> > > + select SYSCON
> > > select SYSRESET
> > > select SYSRESET_WATCHDOG
> > > select SYSRESET_WATCHDOG_AUTO
> > > diff --git a/drivers/power/domain/Kconfig b/drivers/power/domain/Kconfig
> > > index 99b3f9ae71..6ef7a3b3a7 100644
> > > --- a/drivers/power/domain/Kconfig
> > > +++ b/drivers/power/domain/Kconfig
> > > @@ -9,6 +9,14 @@ config POWER_DOMAIN
> > > domains). This may be used to save power. This API provides the
> > > means to control such power management hardware.
> > >
> > > +config APPLE_PMGR_POWER_DOMAIN
> > > + bool "Enable the Apple PMGR power domain driver"
> > > + depends on POWER_DOMAIN
> > > + default y if ARCH_APPLE
> > > + help
> > > + Enable support for manipulating the Apple M1 power domains via
> > > + MMIO mapped registers.
> >
> > Needs more detail here, perhaps a pointer to docs, or something about
> > what the driver supports.
>
> Struggling to come up with more. The "via MMIO mapped registers" is
> already a bit silly. There are no docs. And the one line already
> indicates what the driver supports. Do you want me to add a sentence
> that says the same thing but in different words?

What is PMGR?

What power domains does the driver support? All of them or just a subset?

>
> > > +
> > > config BCM6328_POWER_DOMAIN
> > > bool "Enable the BCM6328 power domain driver"
> > > depends on POWER_DOMAIN && ARCH_BMIPS
> > > diff --git a/drivers/power/domain/Makefile b/drivers/power/domain/Makefile
> > > index 3d1e5f073c..530ae35671 100644
> > > --- a/drivers/power/domain/Makefile
> > > +++ b/drivers/power/domain/Makefile
> > > @@ -4,6 +4,7 @@
> > > #
> > >
> > > obj-$(CONFIG_$(SPL_)POWER_DOMAIN) += power-domain-uclass.o
> > > +obj-$(CONFIG_APPLE_PMGR_POWER_DOMAIN) += apple-pmgr.o
> > > obj-$(CONFIG_BCM6328_POWER_DOMAIN) += bcm6328-power-domain.o
> > > obj-$(CONFIG_IMX8_POWER_DOMAIN) += imx8-power-domain-legacy.o imx8-power-domain.o
> > > obj-$(CONFIG_IMX8M_POWER_DOMAIN) += imx8m-power-domain.o
> > > diff --git a/drivers/power/domain/apple-pmgr.c b/drivers/power/domain/apple-pmgr.c
> > > new file mode 100644
> > > index 0000000000..08a30c8ebf
> > > --- /dev/null
> > > +++ b/drivers/power/domain/apple-pmgr.c
> > > @@ -0,0 +1,113 @@
> > > +// SPDX-License-Identifier: GPL-2.0+
> > > +/*
> > > + * Copyright (C) 2021 Mark Kettenis <kettenis@openbsd.org>
> > > + */
> > > +
> > > +#include <common.h>
> > > +#include <asm/io.h>
> > > +#include <dm.h>
> > > +#include <linux/err.h>
> > > +#include <linux/bitfield.h>
> > > +#include <power-domain-uclass.h>
> > > +#include <regmap.h>
> > > +#include <syscon.h>
> > > +
> > > +#define APPLE_PMGR_PS_TARGET GENMASK(3, 0)
> > > +#define APPLE_PMGR_PS_ACTUAL GENMASK(7, 4)
> > > +
> > > +#define APPLE_PMGR_PS_ACTIVE 0xf
> > > +#define APPLE_PMGR_PS_PWRGATE 0x0
> > > +
> > > +#define APPLE_PMGR_PS_SET_TIMEOUT 100
> >
> > TIMEOUT_MS ?
> > _US ?
>
> _US
>
> > > +
> > > +struct apple_pmgr_priv {
> > > + struct regmap *regmap;
> > > + u32 offset;
> >
> > Needs comment for struct
>
> Really? I mean, I can add a "Device private data" comment, but that's
> pretty much implied by the _priv and the vast majority of the drivers
> don't do such a thing.

What is offset?

>
> >
> > > +};
> > > +
> > > +static int apple_pmgr_request(struct power_domain *power_domain)
> > > +{
> > > + return 0;
> > > +}
> > > +
> > > +static int apple_pmgr_rfree(struct power_domain *power_domain)
> > > +{
> > > + return 0;
> > > +}
> > > +
> > > +static int apple_pmgr_ps_set(struct power_domain *power_domain, u32 pstate)
> > > +{
> > > + struct apple_pmgr_priv *priv = dev_get_priv(power_domain->dev);
> > > + uint reg;
> > > +
> > > + regmap_update_bits(priv->regmap, priv->offset, APPLE_PMGR_PS_TARGET,
> > > + FIELD_PREP(APPLE_PMGR_PS_TARGET, pstate));
> > > +
> > > + return regmap_read_poll_timeout(
> > > + priv->regmap, priv->offset, reg,
> > > + (FIELD_GET(APPLE_PMGR_PS_ACTUAL, reg) == pstate), 1,
> > > + APPLE_PMGR_PS_SET_TIMEOUT);
> > > +}
> > > +
> > > +static int apple_pmgr_on(struct power_domain *power_domain)
> > > +{
> > > + return apple_pmgr_ps_set(power_domain, APPLE_PMGR_PS_ACTIVE);
> > > +}
> > > +
> > > +static int apple_pmgr_off(struct power_domain *power_domain)
> > > +{
> > > + return 0;
> > > +}
> > > +
> > > +static int apple_pmgr_of_xlate(struct power_domain *power_domain,
> > > + struct ofnode_phandle_args *args)
> > > +{
> > > + if (args->args_count != 0) {
> >
> > s/ != 0//
>
> != 0 seems better here since that is the value we're checking for.

It can't be negative though.

[..]

Regards,
Simon