LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: Piyush Mehta <piyush.mehta@xilinx.com>,
	arnd@arndb.de, zou_wei@huawei.com, gregkh@linuxfoundation.org,
	linus.walleij@linaro.org, michal.simek@xilinx.com,
	wendy.liang@xilinx.com, iwamatsu@nigauri.org,
	bgolaszewski@baylibre.com, robh+dt@kernel.org,
	rajan.vaja@xilinx.com
Cc: linux-gpio@vger.kernel.org, devicetree@vger.kernel.org,
	git@xilinx.com, sgoud@xilinx.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Pengutronix Kernel Team <kernel@pengutronix.de>
Subject: Re: [PATCH V3 2/3] dt-bindings: gpio: zynqmp: Add binding documentation for modepin
Date: Wed, 18 Aug 2021 11:00:05 +0200	[thread overview]
Message-ID: <5e44ee87-f727-99fd-9860-d3d58a035dc4@pengutronix.de> (raw)
In-Reply-To: <20210818081018.2620544-3-piyush.mehta@xilinx.com>

On 18.08.21 10:10, Piyush Mehta wrote:
> This patch adds DT binding document for zynqmp modepin GPIO controller.
> Modepin GPIO controller has four GPIO pins which can be configurable
> as input or output.
> 
> Modepin driver is a bridge between the peripheral driver and GPIO pins.
> It has set and get APIs for accessing GPIO pins, based on the device-tree
> entry of reset-gpio property in the peripheral driver, every pin can be
> configured as input/output and trigger GPIO pin.
> 
> For more information please refer zynqMp TRM link:
> Link: https://www.xilinx.com/support/documentation/user_guides/ug1085-zynq-ultrascale-trm.pdf
> Chapter 2: Signals, Interfaces, and Pins
> Table 2-2: Clock, Reset, and Configuration Pins - PS_MODE
> 
> Signed-off-by: Piyush Mehta <piyush.mehta@xilinx.com>
> Acked-by: Michal Simek <michal.simek@xilinx.com>
> ---
> Changes in v2:
> - Addressed review comments: Update commit message
> 
> Review Comments:
> https://lore.kernel.org/linux-arm-kernel/20210615080553.2021061-2-piyush.mehta@xilinx.com/T/#mbd1fbda813e33b19397b350bde75747c92a0d7e1
> https://lore.kernel.org/linux-arm-kernel/20210615080553.2021061-2-piyush.mehta@xilinx.com/T/#me82b1444ab3776162cdb0077dfc9256365c7e736
> 
> Changes in v3:
> - Addressed Rob and Michal review comments:
>   - Update DT example. 
> 
> Review Comments:
> https://lore.kernel.org/linux-arm-kernel/YRbBnRS0VosXcZWz@robh.at.kernel.org/
> https://lore.kernel.org/linux-arm-kernel/d71ad7f9-6972-8cc0-6dfb-b5306c9900d0@xilinx.com/
> ---
>  .../bindings/gpio/xlnx,zynqmp-gpio-modepin.yaml    | 41 ++++++++++++++++++++++
>  .../bindings/gpio/xlnx,zynqmp-gpio-modepin.yaml    | 43 ++++++++++++++++++++++
>  1 file changed, 43 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/gpio/xlnx,zynqmp-gpio-modepin.yaml
> 
> diff --git a/Documentation/devicetree/bindings/gpio/xlnx,zynqmp-gpio-modepin.yaml b/Documentation/devicetree/bindings/gpio/xlnx,zynqmp-gpio-modepin.yaml
> new file mode 100644
> index 0000000..1442815
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/xlnx,zynqmp-gpio-modepin.yaml
> @@ -0,0 +1,43 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: "http://devicetree.org/schemas/gpio/xlnx,zynqmp-gpio-modepin.yaml#"
> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> +
> +title: ZynqMP Mode Pin GPIO controller
> +
> +description:
> +  PS_MODE is 4-bits boot mode pins sampled on POR deassertion. Mode Pin
> +  GPIO controller with configurable from numbers of pins (from 0 to 3 per
> +  PS_MODE). Every pin can be configured as input/output.
So, at Linux runtime, someone decides to boot the system into e.g. a USB
recovery mode and then toggles the appropriate GPIOs and does a system
reset?

If so, are you aware of the reboot mode[1] infrastructure?

A reboot-mode-gpio driver on top of this GPIO controller would allow you
to describe the supported reboot modes in the device tree and instead of
exporting GPIOs to userspace, users can then just do

	systemctl restart recovery

to toggle the appropriate bits.

Also to be sure: PS_MODE are actual GPIO pins that you could toggle
board level components with, right? i.e. it's not just a register that
overrides the values read from the boot mode pins? (In the latter case
a syscon-reboot-mode without GPIO controller would be the correct
abstraction).

[1]: drivers/power/reset/reboot-mode.c

Cheers,
Ahmad

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

  reply	other threads:[~2021-08-18  9:00 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-18  8:10 [PATCH V3 0/3] gpio: modepin: Add driver support for modepin GPIO controller Piyush Mehta
2021-08-18  8:10 ` [PATCH V3 1/3] firmware: zynqmp: Add MMIO read and write support for PS_MODE pin Piyush Mehta
2021-08-18  8:10 ` [PATCH V3 2/3] dt-bindings: gpio: zynqmp: Add binding documentation for modepin Piyush Mehta
2021-08-18  9:00   ` Ahmad Fatoum [this message]
2021-08-18  9:38     ` Michal Simek
2021-08-18  9:55       ` Ahmad Fatoum
2021-08-18 10:01         ` Michal Simek
2021-08-23 18:09   ` Rob Herring
2021-08-18  8:10 ` [PATCH V3 3/3] gpio: modepin: Add driver support for modepin GPIO controller Piyush Mehta
2021-08-18  8:52   ` Ahmad Fatoum
2021-08-18 10:09     ` Piyush Mehta
2021-08-18 13:05       ` Ahmad Fatoum
2021-08-23  8:02   ` Bartosz Golaszewski
2021-08-23  8:14     ` Michal Simek
2021-09-22 10:18       ` Bartosz Golaszewski
2021-09-22 10:21         ` Bartosz Golaszewski
2021-09-22 10:23           ` Michal Simek

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=5e44ee87-f727-99fd-9860-d3d58a035dc4@pengutronix.de \
    --to=a.fatoum@pengutronix.de \
    --cc=arnd@arndb.de \
    --cc=bgolaszewski@baylibre.com \
    --cc=devicetree@vger.kernel.org \
    --cc=git@xilinx.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=iwamatsu@nigauri.org \
    --cc=kernel@pengutronix.de \
    --cc=linus.walleij@linaro.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-gpio@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=michal.simek@xilinx.com \
    --cc=piyush.mehta@xilinx.com \
    --cc=rajan.vaja@xilinx.com \
    --cc=robh+dt@kernel.org \
    --cc=sgoud@xilinx.com \
    --cc=wendy.liang@xilinx.com \
    --cc=zou_wei@huawei.com \
    --subject='Re: [PATCH V3 2/3] dt-bindings: gpio: zynqmp: Add binding documentation for modepin' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).