Subject: Re: [PATCH 2/3] soc: amlogic: Add support for Secure power domains controller

From: Kevin Hilman <[email-masked]>
Date: Wed, 25 Sep 2019 15:41:01 -0700

Hi Jianxin,

Jianxin Pan <[email-masked]> writes:

> Add support for the Amlogic Secure Power controller. In A1/C1 series, power
> control registers are in secure domain, and should be accessed by smc.
>
> Signed-off-by: Jianxin Pan <[email-masked]>
> Signed-off-by: Zhiqiang Liang <[email-masked]>

Thanks for the new power domain driver.

> ---
>  drivers/soc/amlogic/Kconfig             |  13 +++
>  drivers/soc/amlogic/Makefile            |   1 +
>  drivers/soc/amlogic/meson-secure-pwrc.c | 182 ++++++++++++++++++++++++++++++++
>  3 files changed, 196 insertions(+)
>  create mode 100644 drivers/soc/amlogic/meson-secure-pwrc.c
>
> diff --git a/drivers/soc/amlogic/Kconfig b/drivers/soc/amlogic/Kconfig
> index bc2c912..6cb06e7 100644
> --- a/drivers/soc/amlogic/Kconfig
> +++ b/drivers/soc/amlogic/Kconfig
> @@ -48,6 +48,19 @@ config MESON_EE_PM_DOMAINS
>  	  Say yes to expose Amlogic Meson Everything-Else Power Domains as
>  	  Generic Power Domains.
>  
> +config MESON_SECURE_PM_DOMAINS
> +	bool "Amlogic Meson Secure Power Domains driver"
> +	depends on ARCH_MESON || COMPILE_TEST
> +	depends on PM && OF
> +	depends on HAVE_ARM_SMCCC
> +	default ARCH_MESON
> +	select PM_GENERIC_DOMAINS
> +	select PM_GENERIC_DOMAINS_OF
> +	help
> +	  Support for the power controller on Amlogic A1/C1 series.
> +	  Say yes to expose Amlogic Meson Secure Power Domains as Generic
> +	  Power Domains.
> +
>  config MESON_MX_SOCINFO
>  	bool "Amlogic Meson MX SoC Information driver"
>  	depends on ARCH_MESON || COMPILE_TEST
> diff --git a/drivers/soc/amlogic/Makefile b/drivers/soc/amlogic/Makefile
> index de79d044..7b8c5d3 100644
> --- a/drivers/soc/amlogic/Makefile
> +++ b/drivers/soc/amlogic/Makefile
> @@ -5,3 +5,4 @@ obj-$(CONFIG_MESON_GX_SOCINFO) += meson-gx-socinfo.o
>  obj-$(CONFIG_MESON_GX_PM_DOMAINS) += meson-gx-pwrc-vpu.o
>  obj-$(CONFIG_MESON_MX_SOCINFO) += meson-mx-socinfo.o
>  obj-$(CONFIG_MESON_EE_PM_DOMAINS) += meson-ee-pwrc.o
> +obj-$(CONFIG_MESON_SECURE_PM_DOMAINS) += meson-secure-pwrc.o
> diff --git a/drivers/soc/amlogic/meson-secure-pwrc.c b/drivers/soc/amlogic/meson-secure-pwrc.c
> new file mode 100644
> index 00000000..00c7232
> --- /dev/null
> +++ b/drivers/soc/amlogic/meson-secure-pwrc.c
> @@ -0,0 +1,182 @@
> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> +/*
> + * Copyright (c) 2019 Amlogic, Inc.
> + * Author: Jianxin Pan <[email-masked]>
> + */
> +#include <linux/io.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_domain.h>
> +#include <dt-bindings/power/meson-a1-power.h>
> +#include <linux/arm-smccc.h>
> +
> +#define PWRC_ON		1
> +#define PWRC_OFF	0
> +#define SMC_PWRC_SET	0x82000093
> +#define SMC_PWRC_GET	0x82000095
> +
> +struct meson_secure_pwrc_domain {
> +	struct generic_pm_domain base;
> +	unsigned int index;
> +};
> +
> +struct meson_secure_pwrc {
> +	struct meson_secure_pwrc_domain *domains;
> +	struct genpd_onecell_data xlate;
> +};
> +
> +struct meson_secure_pwrc_domain_desc {
> +	unsigned int index;
> +	unsigned int flags;
> +	char *name;
> +	bool (*get_power)(struct meson_secure_pwrc_domain *pwrc_domain);
> +};
> +
> +struct meson_secure_pwrc_domain_data {
> +	unsigned int count;
> +	struct meson_secure_pwrc_domain_desc *domains;
> +};
> +
> +static bool pwrc_secure_get_power(struct meson_secure_pwrc_domain *pwrc_domain)
> +{
> +	struct arm_smccc_res res;
> +
> +	arm_smccc_smc(SMC_PWRC_GET, pwrc_domain->index, 0,
> +		      0, 0, 0, 0, 0, &res);
> +
> +	return res.a0 & 0x1;

Please use a #define with a readable name for this mask.

> +}

What does the return value for this function mean?  Does true mean
"powered off" or "powered on"?

See the rename I just did on the ee-pwrc driver:
https://lore.kernel.org/linux-amlogic/[email-masked]/

> +static int meson_secure_pwrc_off(struct generic_pm_domain *domain)
> +{
> +	struct arm_smccc_res res;
> +	struct meson_secure_pwrc_domain *pwrc_domain =
> +		container_of(domain, struct meson_secure_pwrc_domain, base);
> +
> +	arm_smccc_smc(SMC_PWRC_SET, pwrc_domain->index, PWRC_OFF,
> +		      0, 0, 0, 0, 0, &res);
> +
> +	return 0;
> +}
> +
> +static int meson_secure_pwrc_on(struct generic_pm_domain *domain)
> +{
> +	struct arm_smccc_res res;
> +	struct meson_secure_pwrc_domain *pwrc_domain =
> +		container_of(domain, struct meson_secure_pwrc_domain, base);
> +
> +	arm_smccc_smc(SMC_PWRC_SET, pwrc_domain->index, PWRC_ON,
> +		      0, 0, 0, 0, 0, &res);
> +
> +	return 0;
> +}
> +
> +#define SEC_PD(__name, __flag)			\
> +{						\
> +	.name = #__name,			\
> +	.index = PWRC_##__name##_ID,		\
> +	.get_power = pwrc_secure_get_power,	\
> +	.flags = __flag,			\
> +}
> +
> +static struct meson_secure_pwrc_domain_desc a1_pwrc_domains[] = {
> +	SEC_PD(DSPA,	0),
> +	SEC_PD(DSPB,	0),
> +	SEC_PD(UART,	GENPD_FLAG_ALWAYS_ON),

This flag should only be used for domains where there are no linux
drivers.

Rather than using this flag, you need to add a 'power-domain' property
to the uart driver in DT, and then update the meson_uart driver to use
the runtime PM API so that the domain is enabled whenever the UART is in
use.

> +	SEC_PD(DMC,	GENPD_FLAG_ALWAYS_ON),

Please explain the need for ALWAYS_ON.

> +	SEC_PD(I2C,	0),
> +	SEC_PD(PSRAM,	0),
> +	SEC_PD(ACODEC,	0),
> +	SEC_PD(AUDIO,	0),
> +	SEC_PD(OTP,	0),
> +	SEC_PD(DMA,	0),
> +	SEC_PD(SD_EMMC,	0),
> +	SEC_PD(RAMA,	0),
> +	SEC_PD(RAMB,	GENPD_FLAG_ALWAYS_ON),

Please explain the need for ALWAYS_ON.

> +	SEC_PD(IR,	0),
> +	SEC_PD(SPICC,	0),
> +	SEC_PD(SPIFC,	0),
> +	SEC_PD(USB,	0),
> +	SEC_PD(NIC,	GENPD_FLAG_ALWAYS_ON),

Please explain the need for ALWAYS_ON.

> +	SEC_PD(PDMIN,	0),
> +	SEC_PD(RSA,	0),
> +};
> +
> +static int meson_secure_pwrc_probe(struct platform_device *pdev)
> +{
> +	const struct meson_secure_pwrc_domain_data *match;
> +	struct meson_secure_pwrc *pwrc;
> +	int i;
> +
> +	match = of_device_get_match_data(&pdev->dev);
> +	if (!match) {
> +		dev_err(&pdev->dev, "failed to get match data\n");
> +		return -ENODEV;
> +	}
> +
> +	pwrc = devm_kzalloc(&pdev->dev, sizeof(*pwrc), GFP_KERNEL);
> +	if (!pwrc)
> +		return -ENOMEM;
> +
> +	pwrc->xlate.domains = devm_kcalloc(&pdev->dev, match->count,
> +					   sizeof(*pwrc->xlate.domains),
> +					   GFP_KERNEL);
> +	if (!pwrc->xlate.domains)
> +		return -ENOMEM;
> +
> +	pwrc->domains = devm_kcalloc(&pdev->dev, match->count,
> +				     sizeof(*pwrc->domains), GFP_KERNEL);
> +	if (!pwrc->domains)
> +		return -ENOMEM;
> +
> +	pwrc->xlate.num_domains = match->count;
> +	platform_set_drvdata(pdev, pwrc);
> +
> +	for (i = 0 ; i < match->count ; ++i) {
> +		struct meson_secure_pwrc_domain *dom = &pwrc->domains[i];
> +
> +		if (!match->domains[i].index)
> +			continue;
> +
> +		dom->index = match->domains[i].index;
> +		dom->base.name = match->domains[i].name;
> +		dom->base.flags = match->domains[i].flags;
> +		dom->base.power_on = meson_secure_pwrc_on;
> +		dom->base.power_off = meson_secure_pwrc_off;
> +
> +		pm_genpd_init(&dom->base, NULL,
> +			      (match->domains[i].get_power ?
> +			      match->domains[i].get_power(dom) : true));
> +
> +		pwrc->xlate.domains[i] = &dom->base;
> +	}
> +
> +	return of_genpd_add_provider_onecell(pdev->dev.of_node, &pwrc->xlate);
> +}
> +
> +static struct meson_secure_pwrc_domain_data meson_secure_a1_pwrc_data = {
> +	.domains = a1_pwrc_domains,
> +	.count = ARRAY_SIZE(a1_pwrc_domains),
> +};
> +
> +static const struct of_device_id meson_secure_pwrc_match_table[] = {
> +	{
> +		.compatible = "amlogic,meson-a1-pwrc",
> +		.data = &meson_secure_a1_pwrc_data,
> +	},
> +	{ }

as mentioned by Martin, please add the sentinel string here.  Helps for
readability.

> +};
> +
> +static struct platform_driver meson_secure_pwrc_driver = {
> +	.probe = meson_secure_pwrc_probe,
> +	.driver = {
> +		.name		= "meson_secure_pwrc",
> +		.of_match_table	= meson_secure_pwrc_match_table,
> +	},
> +};
> +
> +static int meson_secure_pwrc_init(void)
> +{
> +	return platform_driver_register(&meson_secure_pwrc_driver);
> +}
> +arch_initcall_sync(meson_secure_pwrc_init);

Please use builtin_platform_driver() or explain in detail why the
initcall is needed.

Thanks,

Kevin

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