From: Bartosz Golaszewski <brgl@bgdev.pl>
To: Charles Keepax <ckeepax@opensource.cirrus.com>
Cc: broonie@kernel.org, linus.walleij@linaro.org,
andy.shevchenko@gmail.com, bard.liao@intel.com,
linux-gpio@vger.kernel.org, linux-spi@vger.kernel.org,
patches@opensource.cirrus.com
Subject: Re: [PATCH v6 1/4] gpio: swnode: Add ability to specify native chip selects for SPI
Date: Tue, 16 Apr 2024 23:09:09 +0200 [thread overview]
Message-ID: <CAMRc=MfKExrzoSe41O_E9TuVTiMq2j8phYiS8dXDg+kmU_EpLg@mail.gmail.com> (raw)
In-Reply-To: <20240415140925.3518990-2-ckeepax@opensource.cirrus.com>
On Mon, Apr 15, 2024 at 4:09 PM Charles Keepax
<ckeepax@opensource.cirrus.com> wrote:
>
> SPI devices can specify a cs-gpios property to enumerate their
> chip selects. Under device tree, a zero entry in this property can
> be used to specify that a particular chip select is using the SPI
> controllers native chip select, for example:
>
> cs-gpios = <&gpio1 0 0>, <0>;
>
> Here, the second chip select is native. However, when using swnodes
> there is currently no way to specify a native chip select. The
> proposal here is to register a swnode_gpio_undefined software node,
> that can be specified to allow the indication of a native chip
> select. For example:
>
> static const struct software_node_ref_args device_cs_refs[] = {
> {
> .node = &device_gpiochip_swnode,
> .nargs = 2,
> .args = { 0, GPIO_ACTIVE_LOW },
> },
> {
> .node = &swnode_gpio_undefined,
> .nargs = 0,
> },
> };
>
> Register the swnode as the gpiolib is initialised and check in
> swnode_get_gpio_device() if the returned node matches
> swnode_gpio_undefined and return -ENOENT, which matches the
> behaviour of the device tree system when it encounters a 0 phandle.
>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
> ---
>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
next prev parent reply other threads:[~2024-04-16 21:09 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-15 14:09 [PATCH v6 0/4] Add bridged amplifiers to cs42l43 Charles Keepax
2024-04-15 14:09 ` [PATCH v6 1/4] gpio: swnode: Add ability to specify native chip selects for SPI Charles Keepax
2024-04-15 16:05 ` Andy Shevchenko
2024-04-16 21:09 ` Bartosz Golaszewski [this message]
2024-04-15 14:09 ` [PATCH v6 2/4] spi: Switch to using is_acpi_device_node() in spi_dev_set_name() Charles Keepax
2024-04-15 16:06 ` Andy Shevchenko
2024-04-16 9:53 ` Charles Keepax
2024-04-15 14:09 ` [PATCH v6 3/4] spi: Update swnode based SPI devices to use the fwnode name Charles Keepax
2024-04-15 16:09 ` Andy Shevchenko
2024-04-15 14:09 ` [PATCH v6 4/4] spi: cs42l43: Add bridged cs35l56 amplifiers Charles Keepax
2024-04-15 16:17 ` Andy Shevchenko
2024-04-16 9:54 ` Charles Keepax
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