From: Linus Walleij <linus.walleij@linaro.org>
To: Khouloud Touil <ktouil@baylibre.com>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
baylibre-upstreaming@groups.io,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
linux-i2c <linux-i2c@vger.kernel.org>
Subject: Re: [PATCH 1/4] dt-bindings: nvmem: new optional property write-protect-gpios
Date: Fri, 22 Nov 2019 13:41:08 +0100 [thread overview]
Message-ID: <CACRpkdaZrvPObjyN4kasARzKZ9=PiAcvTzXzWkmC7R+Ay5tU8w@mail.gmail.com> (raw)
In-Reply-To: <20191120142038.30746-2-ktouil@baylibre.com>
Hi Khouloud,
thanks for your patch!
I just have a semantic comment:
On Wed, Nov 20, 2019 at 3:21 PM Khouloud Touil <ktouil@baylibre.com> wrote:
> Instead of modifying all the memory drivers to check this pin, make
> the NVMEM subsystem check if the write-protect GPIO being passed
> through the nvmem_config or defined in the device tree and pull it
> low whenever writing to the memory.
It is claimed that this should be pulled low to assert it so by
definition it is active low.
> + wp-gpios:
> + description:
> + GPIO to which the write-protect pin of the chip is connected.
> + maxItems: 1
Mandate that the flag in the second cell should be GPIO_ACTIVE_LOW
> patternProperties:
> "^.*@[0-9a-f]+$":
> type: object
> @@ -66,6 +71,7 @@ examples:
> qfprom: eeprom@700000 {
> #address-cells = <1>;
> #size-cells = <1>;
> + wp-gpios = <&gpio1 3 0>;
#include <dt-bindings/gpio/gpio.h>
wp-gpios = <&gpio1 3 GPIO_ACTIVE_LOW>;
This will in Linux have the semantic effect that you need to
set the output high with gpio_set_val(d, 1) to assert it
(drive it low) but that really doesn't matter to the device tree
bindings, those are OS-agnostic: if the line is active low then
it should use this flag.
It has the upside that the day you need a write-protect that
is active high, it is simple to support that use case too.
Yours,
Linus Walleij
next prev parent reply other threads:[~2019-11-22 12:41 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-20 14:20 [PATCH 0/4] at24: move write-protect pin handling to nvmem core Khouloud Touil
2019-11-20 14:20 ` [PATCH 1/4] dt-bindings: nvmem: new optional property write-protect-gpios Khouloud Touil
2019-11-22 12:41 ` Linus Walleij [this message]
2019-11-22 12:47 ` Bartosz Golaszewski
2019-11-22 12:53 ` Linus Walleij
2019-11-22 13:04 ` Bartosz Golaszewski
2019-11-22 13:46 ` Linus Walleij
[not found] ` <CALL1Z1xpcGyh_f3ooRT+gGApoAnS7YBMd2hUKqnt+pTcAFoeAg@mail.gmail.com>
2019-11-28 13:44 ` Linus Walleij
2019-11-29 8:47 ` Bartosz Golaszewski
2019-12-04 15:14 ` Rob Herring
2019-11-22 13:10 ` Peter Rosin
2019-11-20 14:20 ` [PATCH 2/4] nvmem: add support for the write-protect pin Khouloud Touil
2019-11-22 12:47 ` Linus Walleij
2019-11-20 14:20 ` [PATCH 3/4] dt-bindings: at24: remove the optional property write-protect-gpios Khouloud Touil
2019-12-04 15:22 ` Rob Herring
2019-11-20 14:20 ` [PATCH 4/4] eeprom: at24: remove the write-protect pin support Khouloud Touil
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