Received-SPF: pass (google.com: domain of linux-kernel+bounces-59966-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Precedence: bulk
MIME-Version: 1.0
References: <20240208161700.268570-1-peter.griffin@linaro.org> <20240208161700.268570-2-peter.griffin@linaro.org>
In-Reply-To: <20240208161700.268570-2-peter.griffin@linaro.org>
From: Sam Protsenko <semen.protsenko@linaro.org>
Date: Fri, 9 Feb 2024 14:50:48 -0600
Message-ID: <CAPLW+4mSyqnkzz5N1seFoaDAR1pd_jQEO3ThkGf3U_ozfwedyA@mail.gmail.com>
Subject: Re: [PATCH v4 1/2] soc: samsung: exynos-pmu: Add regmap support for
 SoCs that protect PMU regs
To: Peter Griffin <peter.griffin@linaro.org>
Cc: arnd@arndb.de, krzysztof.kozlowski@linaro.org, linux@roeck-us.net, 
	wim@linux-watchdog.org, alim.akhtar@samsung.com, jaewon02.kim@samsung.com, 
	alexey.klimov@linaro.org, kernel-team@android.com, tudor.ambarus@linaro.org, 
	andre.draszik@linaro.org, saravanak@google.com, willmcvicker@google.com, 
	linux-fsd@tesla.com, linux-watchdog@vger.kernel.org, 
	linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, 
	linux-samsung-soc@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Thu, Feb 8, 2024 at 10:21=E2=80=AFAM Peter Griffin <peter.griffin@linaro=
org> 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.
>
> As most Exynos drivers that need to write PMU registers currently obtain =
a
> regmap via syscon (phys, pinctrl, watchdog). Support for the above usecas=
e
> is implemented in this driver using a custom regmap similar to syscon to
> handle the SMC call. Platforms that don't secure PMU registers, get a mmi=
o
> regmap like before. As regmaps abstract out the underlying register acces=
s
> changes to the leaf drivers are minimal.
>
> A new API exynos_get_pmu_regmap_by_phandle() is provided for leaf drivers
> that currently use syscon_regmap_lookup_by_phandle(). This also handles
> deferred probing.
>
> Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
> ---
> Changes since v3:
>  - Fix PMUALIVE_MASK
>  - Add TENSOR_ prefix
>  - clear SET_BITS bits on each loop iteration
>  - change set_bit to set_bits in func name
>  - Fix some alignment
>  - Add missing return on dev_err_probe
>  - Reduce indentation in loop
>
> Changes since v2
>  - Add select REGMAP to Kconfig
>  - Add constant for SET/CLEAR bits
>  - Replace kerneldoc with one line comment
>  - Fix kerneldoc for EXPORT_SYMBOL_GPL funcs
>  - remove superfluous extern keyword
>  - dev_err_probe() on probe error
>  - shorten regmcfg name
>  - no compatibles inside probe, use match data
>  - don't mix declarations with/without initializations
>  - tensor_sec_reg_read() use mmio to avoid access restrictions
>  - Collect up Reviewed-by
>  - const for regmap_config structs
> ---

Tested-by: Sam Protsenko <semen.protsenko@linaro.org>

Tested on my E850-96. All modules that use PMU are still functional
with this patch (watchdog, USB host and Ethernet). No regressions.

[snip]