From: AKASHI Takahiro <takahiro.akashi@linaro.org>
To: sudeep.holla@arm.com, cristian.marussi@arm.com,
robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
conor+dt@kernel.org, linus.walleij@linaro.org
Cc: Oleksii_Moisieiev@epam.com, linux-arm-kernel@lists.infradead.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-gpio@vger.kernel.org,
AKASHI Takahiro <takahiro.akashi@linaro.org>
Subject: [RFC v2 0/5] gpio: add pinctrl based generic gpio driver
Date: Thu, 5 Oct 2023 11:58:38 +0900 [thread overview]
Message-ID: <20231005025843.508689-1-takahiro.akashi@linaro.org> (raw)
This is a revised version of my previous RFC[1]. Although I modified
the commits to make them look SCMI-independent, they are still posted
as RFC because I have never tested them on real hardware.
(background)
I'm currently working on implementing SCMI pinctrl/gpio drivers
on U-Boot[2]. Although the pinctrl driver for the kernel[3] was submitted
by EPAM, it doesn't contain the gpio driver and I believe that we should
discuss a couple of points on the kernel side to finalize my design for
U-Boot.
So this RFC is intended for reviews, especially to raise some issues.
1) how to obtain a value on an input pin
All the existing gpio drivers are set to obtain a value on an input
pin by accessing the hardware directly. In SCMI case, however, this is
just impossible in its nature and must be supported via a protocol
using "Input-value" configuration type. (See the spec[4], table-23.)
The current pinconf framework is missing the feature (the pinconf
parameter and a helper function). See patch#1, #2 and #3.
Please note that there is an issue around the pin configuration in
EPAM's current pinctrl driver as I commented[5].
2) DT bindings
I would like to propose a generic binding for pinctrl based gpio driver.
This allows a "consumer" driver to handle gpio pins like as other
normal gpio controllers support. (patch#5)
3) generic GPIO driver
Based on (2), I tried to prototype a generic driver in patch#4.
Thanks to a set of existing pinctrl_gpio helper functions, except (1),
It seems that the driver can be implemented not relying on pin controller
specific code, at least for SCMI pinctrl.
I will appreciate any comments.
-Takahiro Akashi
[1] https://lkml.iu.edu//hypermail/linux/kernel/2310.0/00362.html
[2] https://lists.denx.de/pipermail/u-boot/2023-September/529765.html
[3] https://lkml.iu.edu/hypermail/linux/kernel/2308.1/01082.html
[4] https://developer.arm.com/documentation/den0056/
[5] https://lkml.iu.edu/hypermail/linux/kernel/2308.2/07483.html
AKASHI Takahiro (5):
pinctrl: define PIN_CONFIG_INPUT
pinctrl: always export pin_config_get_for_pin()
pinctrl: add pinctrl_gpio_get_config()
gpio: add pinctrl based generic gpio driver
dt-bindings: gpio: Add bindings for pinctrl based generic gpio driver
.../bindings/gpio/pin-control-gpio.yaml | 55 ++++++
drivers/gpio/Kconfig | 7 +
drivers/gpio/Makefile | 1 +
drivers/gpio/gpio-by-pinctrl.c | 165 ++++++++++++++++++
drivers/pinctrl/core.c | 19 ++
drivers/pinctrl/pinconf.h | 10 +-
include/linux/pinctrl/consumer.h | 8 +
include/linux/pinctrl/pinconf-generic.h | 5 +
8 files changed, 268 insertions(+), 2 deletions(-)
create mode 100644 Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
create mode 100644 drivers/gpio/gpio-by-pinctrl.c
--
2.34.1
next reply other threads:[~2023-10-05 14:18 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-05 2:58 AKASHI Takahiro [this message]
2023-10-05 2:58 ` [RFC v2 1/5] pinctrl: define PIN_CONFIG_INPUT AKASHI Takahiro
2023-10-10 11:53 ` Linus Walleij
2023-10-05 2:58 ` [RFC v2 2/5] pinctrl: always export pin_config_get_for_pin() AKASHI Takahiro
2023-10-10 11:54 ` Linus Walleij
2023-10-05 2:58 ` [RFC v2 3/5] pinctrl: add pinctrl_gpio_get_config() AKASHI Takahiro
2023-10-05 2:58 ` [RFC v2 4/5] gpio: add pinctrl based generic gpio driver AKASHI Takahiro
2023-10-10 12:00 ` Linus Walleij
2023-10-12 1:08 ` AKASHI Takahiro
2023-10-05 2:58 ` [RFC v2 5/5] dt-bindings: gpio: Add bindings for " AKASHI Takahiro
2023-10-05 19:48 ` Krzysztof Kozlowski
2023-10-12 1:15 ` AKASHI Takahiro
2023-10-12 7:27 ` Krzysztof Kozlowski
2023-10-06 13:18 ` Rob Herring
2023-10-06 13:23 ` Rob Herring
2023-10-09 7:49 ` Linus Walleij
2023-10-09 9:08 ` Cristian Marussi
2023-10-09 13:13 ` Linus Walleij
2023-10-09 15:08 ` Cristian Marussi
2023-10-10 5:14 ` AKASHI Takahiro
2023-10-10 5:25 ` AKASHI Takahiro
2023-10-12 7:25 ` Linus Walleij
2023-10-17 2:32 ` AKASHI Takahiro
2023-10-23 8:12 ` Linus Walleij
2023-10-24 7:12 ` AKASHI Takahiro
2023-10-24 9:40 ` Linus Walleij
2023-10-24 10:55 ` Cristian Marussi
2023-10-24 13:01 ` Linus Walleij
2023-10-24 11:09 ` AKASHI Takahiro
2023-10-24 13:12 ` Linus Walleij
2023-10-24 13:42 ` AKASHI Takahiro
2023-11-05 22:15 ` Linus Walleij
2023-10-19 21:27 ` [RFC v2 0/5] gpio: add " andy.shevchenko
2023-10-20 0:21 ` AKASHI Takahiro
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