linux-kernel - Re: [PATCH v3 5/5] i2c: muxes: pca954x: Allow sharing reset GPIO

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Date: Tue, 16 Jan 2024 16:18:34 +0100
From: Philipp Zabel <p.zabel@...gutronix.de>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>, Bjorn Andersson
 <andersson@...nel.org>, Konrad Dybcio <konrad.dybcio@...aro.org>, Srinivas
 Kandagatla <srinivas.kandagatla@...aro.org>, Banajit Goswami
 <bgoswami@...cinc.com>, Liam Girdwood <lgirdwood@...il.com>, Mark Brown
 <broonie@...nel.org>, Rob Herring <robh+dt@...nel.org>, Krzysztof Kozlowski
 <krzysztof.kozlowski+dt@...aro.org>,  Conor Dooley <conor+dt@...nel.org>,
 Peter Rosin <peda@...ntia.se>, Jaroslav Kysela <perex@...ex.cz>,  Takashi
 Iwai <tiwai@...e.com>, linux-arm-msm@...r.kernel.org,
 alsa-devel@...a-project.org,  linux-sound@...r.kernel.org,
 devicetree@...r.kernel.org,  linux-kernel@...r.kernel.org,
 linux-i2c@...r.kernel.org
Cc: Chris Packham <chris.packham@...iedtelesis.co.nz>, Bartosz Golaszewski
	 <brgl@...ev.pl>, Sean Anderson <sean.anderson@...o.com>
Subject: Re: [PATCH v3 5/5] i2c: muxes: pca954x: Allow sharing reset GPIO

On Fr, 2024-01-12 at 17:36 +0100, Krzysztof Kozlowski wrote:
> From: Chris Packham <chris.packham@...iedtelesis.co.nz>
> 
> Some hardware designs with multiple PCA954x devices use a reset GPIO
> connected to all the muxes. Support this configuration by making use of
> the reset controller framework which can deal with the shared reset
> GPIOs. Fall back to the old GPIO descriptor method if the reset
> controller framework is not enabled.
> 
> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
> Acked-by: Peter Rosin <peda@...ntia.se>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> Link: https://lore.kernel.org/r/20240108041913.7078-1-chris.packham@alliedtelesis.co.nz
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> 
> ---
> 
> If previous patches are fine, then this commit is independent and could
> be taken via I2C.
> 
> Cc: Chris Packham <chris.packham@...iedtelesis.co.nz>
> Cc: Bartosz Golaszewski <brgl@...ev.pl>
> Cc: Sean Anderson <sean.anderson@...o.com>
> ---
>  drivers/i2c/muxes/i2c-mux-pca954x.c | 46 ++++++++++++++++++++++++-----
>  1 file changed, 38 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
> index 2219062104fb..1702e8d49b91 100644
> --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
> +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
> @@ -49,6 +49,7 @@
>  #include <linux/pm.h>
>  #include <linux/property.h>
>  #include <linux/regulator/consumer.h>
> +#include <linux/reset.h>
>  #include <linux/slab.h>
>  #include <linux/spinlock.h>
>  #include <dt-bindings/mux/mux.h>
> @@ -102,6 +103,9 @@ struct pca954x {
>  	unsigned int irq_mask;
>  	raw_spinlock_t lock;
>  	struct regulator *supply;
> +
> +	struct gpio_desc *reset_gpio;
> +	struct reset_control *reset_cont;
>  };
>  
>  /* Provide specs for the MAX735x, PCA954x and PCA984x types we know about */
> @@ -477,6 +481,35 @@ static int pca954x_init(struct i2c_client *client, struct pca954x *data)
>  	return ret;
>  }
>  
> +static int pca954x_get_reset(struct device *dev, struct pca954x *data)
> +{
> +	data->reset_cont = devm_reset_control_get_optional_shared(dev, NULL);
> +	if (IS_ERR(data->reset_cont))
> +		return dev_err_probe(dev, PTR_ERR(data->reset_cont),
> +				     "Failed to get reset\n");
> +	else if (data->reset_cont)
> +		return 0;
> +
> +	/*
> +	 * fallback to legacy reset-gpios
> +	 */

devm_reset_control_get_optional_shared() won't return NULL if the
"reset-gpios" property is found in the device tree, so the GPIO
fallback is dead code.

> +	data->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(data->reset_gpio)) {
> +		return dev_err_probe(dev, PTR_ERR(data->reset_gpio),
> +				     "Failed to get reset gpio");
> +	}
> +
> +	return 0;
> +}
> +

regards
Philipp