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

From: Kevin Hilman <[email-masked]>
Date: Thu, 26 Sep 2019 09:23:42 -0700

Jianxin Pan <[email-masked]> writes:

> Hi Kevin,
>
> Thanks for your review. Please see my comments below.
>
>
> On 2019/9/26 6:41, Kevin Hilman wrote:
>> 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)
> [...]
>>> +
>>> +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.
>> The return type of this smc is bool. I will remove 0x1 mask in next version. 
>
> Another question about smc:
> In this driver, no share memory is needed, and I use arm_smccc_smc() directly.
> Should I add secure-monitor = <&sm> in dtb and use meson_sm_call() from sm driver instead? 

Yes, that would be preferred.

>>> +}
>> 
>> What does the return value for this function mean?  Does true mean
>> "powered off" or "powered on">
> The return vaule for SMC_PWRC_GET :
> 0 -> power on
> 1 -> power off> See the rename I just did on the ee-pwrc driver:
>> https://lore.kernel.org/linux-amlogic/[email-masked]/
>> I will follow and rename to _is_off() in the next verson.
>>> +static int meson_secure_pwrc_off(struct generic_pm_domain *domain)
>>> +{
>>> +	struct arm_smccc_res res;
>>> +	struct meson_secure_pwrc_domain *pwrc_domain =
> [...]
>>> +
>>> +#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.
>
> PM_UART Power domain is shared by uart, msr, jtag and cec.
> Uart should keep working in BL31, after kernel suspend and before kernel resume.

OK.

>> 
>>> +	SEC_PD(DMC,	GENPD_FLAG_ALWAYS_ON),
>> 
>> Please explain the need for ALWAYS_ON.
>> 
> PM_DMC is used for DDR PHY ana/dig and DMC. 
> There is no linux drver for them, and it should be always on. 
>
> I will add comments for all these always on domains.

OK, thank you.

Kevin

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