linux-kernel - Re: [PATCH V15 6/9] mfd: pm8008: Use i2c_new_dummy

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Message-ID: <YquZRcuRCrdF+Q1z@google.com>
Date:   Thu, 16 Jun 2022 21:57:41 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Satya Priya <quic_c_skakit@...cinc.com>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        swboyd@...omium.org, quic_collinsd@...cinc.com,
        quic_subbaram@...cinc.com, quic_jprakash@...cinc.com
Subject: Re: [PATCH V15 6/9] mfd: pm8008: Use i2c_new_dummy_device() API

On Tue, 14 Jun 2022, Satya Priya wrote:

> Use i2c_new_dummy_device() to register pm8008-regulator
> client present at a different address space, instead of
> defining a separate DT node. This avoids calling the probe
> twice for the same chip, once for each client pm8008-infra
> and pm8008-regulator.
> 
> As a part of this define pm8008_regmap_init() to do regmap
> init for both the clients and define pm8008_get_regmap() to
> pass the regmap to the regulator driver.
> 
> Signed-off-by: Satya Priya <quic_c_skakit@...cinc.com>
> Reviewed-by: Stephen Boyd <swboyd@...omium.org>
> ---
> Changes in V15:
>  - None.
> 
> Changes in V14:
>  - None.
> 
> Changes in V13:
>  - None.
> 
>  drivers/mfd/qcom-pm8008.c       | 34 ++++++++++++++++++++++++++++++++--
>  include/linux/mfd/qcom_pm8008.h |  9 +++++++++
>  2 files changed, 41 insertions(+), 2 deletions(-)
>  create mode 100644 include/linux/mfd/qcom_pm8008.h
> 
> diff --git a/drivers/mfd/qcom-pm8008.c b/drivers/mfd/qcom-pm8008.c
> index 569ffd50..55e2a8e 100644
> --- a/drivers/mfd/qcom-pm8008.c
> +++ b/drivers/mfd/qcom-pm8008.c
> @@ -9,6 +9,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/irq.h>
>  #include <linux/irqdomain.h>
> +#include <linux/mfd/qcom_pm8008.h>
>  #include <linux/module.h>
>  #include <linux/of_device.h>
>  #include <linux/of_platform.h>
> @@ -57,6 +58,7 @@ enum {
>  
>  struct pm8008_data {
>  	struct device *dev;
> +	struct regmap *regulators_regmap;
>  	int irq;
>  	struct regmap_irq_chip_data *irq_data;
>  };
> @@ -150,6 +152,12 @@ static struct regmap_config qcom_mfd_regmap_cfg = {
>  	.max_register	= 0xFFFF,
>  };
>  
> +struct regmap *pm8008_get_regmap(const struct pm8008_data *chip)
> +{
> +	return chip->regulators_regmap;
> +}
> +EXPORT_SYMBOL_GPL(pm8008_get_regmap);

Seems like abstraction for the sake of abstraction.

Why not do the dereference inside the regulator driver?

>  static int pm8008_init(struct regmap *regmap)
>  {
>  	int rc;
> @@ -217,11 +225,25 @@ static int pm8008_probe_irq_peripherals(struct pm8008_data *chip,
>  	return 0;
>  }
>  
> +static struct regmap *pm8008_regmap_init(struct i2c_client *client,
> +							struct pm8008_data *chip)
> +{
> +	struct regmap *regmap;
> +
> +	regmap = devm_regmap_init_i2c(client, &qcom_mfd_regmap_cfg);
> +	if (!regmap)
> +		return NULL;
> +
> +	i2c_set_clientdata(client, chip);
> +	return regmap;
> +}

This function seems superfluous.

It's only called once and it contains a single call.

Just pop the call directly into probe.

>  static int pm8008_probe(struct i2c_client *client)
>  {
>  	int rc;
>  	struct pm8008_data *chip;
>  	struct gpio_desc *reset_gpio;
> +	struct i2c_client *regulators_client;
>  	struct regmap *regmap;
>  
>  	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
> @@ -229,11 +251,19 @@ static int pm8008_probe(struct i2c_client *client)
>  		return -ENOMEM;
>  
>  	chip->dev = &client->dev;
> -	regmap = devm_regmap_init_i2c(client, &qcom_mfd_regmap_cfg);
> +	regmap = pm8008_regmap_init(client, chip);
>  	if (!regmap)
>  		return -ENODEV;
>  
> -	i2c_set_clientdata(client, chip);
> +	regulators_client = i2c_new_dummy_device(client->adapter, client->addr + 1);
> +	if (IS_ERR(regulators_client)) {
> +		dev_err(&client->dev, "can't attach client\n");
> +		return PTR_ERR(regulators_client);
> +	}
> +
> +	chip->regulators_regmap = pm8008_regmap_init(regulators_client, chip);
> +	if (!chip->regulators_regmap)
> +		return -ENODEV;
>  
>  	reset_gpio = devm_gpiod_get(chip->dev, "reset", GPIOD_OUT_LOW);
>  	if (IS_ERR(reset_gpio))
> diff --git a/include/linux/mfd/qcom_pm8008.h b/include/linux/mfd/qcom_pm8008.h
> new file mode 100644
> index 0000000..3814bff
> --- /dev/null
> +++ b/include/linux/mfd/qcom_pm8008.h
> @@ -0,0 +1,9 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +// Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
> +#ifndef __QCOM_PM8008_H__
> +#define __QCOM_PM8008_H__
> +
> +struct pm8008_data;
> +struct regmap *pm8008_get_regmap(const struct pm8008_data *chip);
> +
> +#endif

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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