linux-kernel - Re: [PATCH 2/7] phy: exynos5-usbdrd: use exynos_get_pmu_regmap_by

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Date: Thu, 25 Apr 2024 09:47:23 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: André Draszik <andre.draszik@...aro.org>,
 Vinod Koul <vkoul@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Peter Griffin
 <peter.griffin@...aro.org>, Marek Szyprowski <m.szyprowski@...sung.com>,
 Sylwester Nawrocki <s.nawrocki@...sung.com>,
 Alim Akhtar <alim.akhtar@...sung.com>,
 Sam Protsenko <semen.protsenko@...aro.org>
Cc: Krzysztof Kozlowski <krzk@...nel.org>,
 Tudor Ambarus <tudor.ambarus@...aro.org>,
 Will McVicker <willmcvicker@...gle.com>, Roy Luo <royluo@...gle.com>,
 kernel-team@...roid.com, linux-phy@...ts.infradead.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH 2/7] phy: exynos5-usbdrd: use
 exynos_get_pmu_regmap_by_phandle() for PMU regs

On 23/04/2024 19:06, André Draszik wrote:
> Some Exynos based SoCs like Tensor gs101 protect the PMU registers for
> security hardening reasons so that they are only write accessible in
> EL3 via an SMC call.
> 
> The Exynos PMU driver handles this transparently when using
> exynos_get_pmu_regmap_by_phandle().
> 
> Switch to using that API to support such SoCs. As this driver now no
> longer depends on mfd syscon remove that header and Kconfig dependency.
> 
> Signed-off-by: André Draszik <andre.draszik@...aro.org>
> ---
>  drivers/phy/samsung/Kconfig              | 1 -
>  drivers/phy/samsung/phy-exynos5-usbdrd.c | 4 ++--
>  2 files changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/phy/samsung/Kconfig b/drivers/phy/samsung/Kconfig
> index f10afa3d7ff5..bb63fa710803 100644
> --- a/drivers/phy/samsung/Kconfig
> +++ b/drivers/phy/samsung/Kconfig
> @@ -82,7 +82,6 @@ config PHY_EXYNOS5_USBDRD
>  	depends on HAS_IOMEM
>  	depends on USB_DWC3_EXYNOS
>  	select GENERIC_PHY
> -	select MFD_SYSCON
>  	default y
>  	help
>  	  Enable USB DRD PHY support for Exynos 5 SoC series.
> diff --git a/drivers/phy/samsung/phy-exynos5-usbdrd.c b/drivers/phy/samsung/phy-exynos5-usbdrd.c
> index 04171eed5b16..ac208b89f5a6 100644
> --- a/drivers/phy/samsung/phy-exynos5-usbdrd.c
> +++ b/drivers/phy/samsung/phy-exynos5-usbdrd.c
> @@ -18,9 +18,9 @@
>  #include <linux/phy/phy.h>
>  #include <linux/platform_device.h>
>  #include <linux/mutex.h>
> -#include <linux/mfd/syscon.h>
>  #include <linux/regmap.h>
>  #include <linux/regulator/consumer.h>
> +#include <linux/soc/samsung/exynos-pmu.h>
>  #include <linux/soc/samsung/exynos-regs-pmu.h>

This is getting out of hand: shall we expect to convert all the drivers
from generic syscon to Exynos-specific API? What if one driver is some
shared IP, like DWC USB3 controller?

I already commented on Google hwrng driver: I prefer to keep the syscon
API and change the syscon driver to expose proper regmap. IOW, use
generic API syscon_regmap_lookup_by_phandle() and the type of regmap
returned is defined by the provider (so node pointed by phandle).

Best regards,
Krzysztof