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Date:   Tue, 28 Jun 2022 10:23:19 +0530
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Subject: Re: [PATCH V15 6/9] mfd: pm8008: Use i2c_new_dummy_device() API
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To:     Lee Jones <lee.jones@linaro.org>
CC:     Bjorn Andersson <bjorn.andersson@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        <linux-arm-msm@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <swboyd@chromium.org>,
        <quic_collinsd@quicinc.com>, <quic_subbaram@quicinc.com>,
        <quic_jprakash@quicinc.com>
References: <1655200111-18357-1-git-send-email-quic_c_skakit@quicinc.com>
 <1655200111-18357-7-git-send-email-quic_c_skakit@quicinc.com>
 <YquZRcuRCrdF+Q1z@google.com>
 <eccbb030-97f7-3a6c-958e-05adcdca6210@quicinc.com>
 <YrAt6dq6ty9p8d05@google.com>
 <a11732d6-a9b1-7ead-e89a-564a57a7192b@quicinc.com>
 <503f1a8b-eadb-d3a6-6e24-d60437f778b6@quicinc.com>
 <YrlfF+DMlGFsVBdk@google.com>
From:   "Satya Priya Kakitapalli (Temp)" <quic_c_skakit@quicinc.com>
In-Reply-To: <YrlfF+DMlGFsVBdk@google.com>
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On 6/27/2022 1:11 PM, Lee Jones wrote:
> On Mon, 27 Jun 2022, Satya Priya Kakitapalli (Temp) wrote:
>
>> Hi Lee,
>>
>>
>> On 6/20/2022 4:37 PM, Satya Priya Kakitapalli (Temp) wrote:
>>> On 6/20/2022 1:50 PM, Lee Jones wrote:
>>>> On Mon, 20 Jun 2022, Satya Priya Kakitapalli (Temp) wrote:
>>>>
>>>>> On 6/17/2022 2:27 AM, Lee Jones wrote:
>>>>>> 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@quicinc.com>
>>>>>>> Reviewed-by: Stephen Boyd <swboyd@chromium.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?
>>>>> To derefer this in the regulator driver, we need to have the
>>>>> pm8008_data
>>>>> struct definition in the qcom_pm8008 header file.
>>>>>
>>>>> I think it doesn't look great to have only that structure in
>>>>> header and all
>>>>> other structs and enum in the mfd driver.
>>>> Then why pass 'pm8008_data' at all?
>>>
>>> There is one more option, instead of passing the pm8008_data, we could
>>> pass the pdev->dev.parent and get the pm8008 chip data directly in the
>>> pm8008_get_regmap() like below
>>>
>>>
>>> struct regmap *pm8008_get_regmap(const struct device *dev)
>>>   {
>>>       const struct pm8008_data *chip = dev_get_drvdata(dev);
>>>
>>>       return chip->regulators_regmap;
>>> }
>>> EXPORT_SYMBOL_GPL(pm8008_get_regmap);
>>>
>>>
>>> By doing this we can avoid having declaration of pm8008_data also in the
>>> header. Please let me know if this looks good.
>>>
>> Could you please confirm on this?
>>
>>>> What's preventing you from passing 'regmap'?
>>>
>>> I didn't get what you meant here, could you please elaborate a bit?
> Ah yes.  I authored you a patch, but became distracted. Here:
>
> -----8<--------------------8<-------
>
> From: Lee Jones <lee.jones@linaro.org>
>
> mfd: pm8008: Remove driver data structure pm8008_data
>      
> Maintaining a local driver data structure that is never shared
> outside of the core device is an unnecessary complexity.  Half of the
> attributes were not used outside of a single function, one of which
> was not used at all.  The remaining 2 are generic and can be passed
> around as required.


Okay, but we still need to store the regulators_regmap, which is 
required in the pm8008 regulator driver. Could we use a global variable 
for it?


> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> ---
>   drivers/mfd/qcom-pm8008.c | 53 ++++++++++++++++++-----------------------------
>   1 file changed, 20 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/mfd/qcom-pm8008.c b/drivers/mfd/qcom-pm8008.c
> index c472d7f8103c4..4b8ff947762f2 100644
> --- a/drivers/mfd/qcom-pm8008.c
> +++ b/drivers/mfd/qcom-pm8008.c
> @@ -54,13 +54,6 @@ enum {
>   
>   #define PM8008_PERIPH_OFFSET(paddr)	(paddr - PM8008_PERIPH_0_BASE)
>   
> -struct pm8008_data {
> -	struct device *dev;
> -	struct regmap *regmap;
> -	int irq;
> -	struct regmap_irq_chip_data *irq_data;
> -};
> -
>   static unsigned int p0_offs[] = {PM8008_PERIPH_OFFSET(PM8008_PERIPH_0_BASE)};
>   static unsigned int p1_offs[] = {PM8008_PERIPH_OFFSET(PM8008_PERIPH_1_BASE)};
>   static unsigned int p2_offs[] = {PM8008_PERIPH_OFFSET(PM8008_PERIPH_2_BASE)};
> @@ -150,7 +143,7 @@ static struct regmap_config qcom_mfd_regmap_cfg = {
>   	.max_register	= 0xFFFF,
>   };
>   
> -static int pm8008_init(struct pm8008_data *chip)
> +static int pm8008_init(struct regmap *regmap)
>   {
>   	int rc;
>   
> @@ -160,34 +153,31 @@ static int pm8008_init(struct pm8008_data *chip)
>   	 * This is required to enable the writing of TYPE registers in
>   	 * regmap_irq_sync_unlock().
>   	 */
> -	rc = regmap_write(chip->regmap,
> -			 (PM8008_TEMP_ALARM_ADDR | INT_SET_TYPE_OFFSET),
> -			 BIT(0));
> +	rc = regmap_write(regmap, (PM8008_TEMP_ALARM_ADDR | INT_SET_TYPE_OFFSET), BIT(0));
>   	if (rc)
>   		return rc;
>   
>   	/* Do the same for GPIO1 and GPIO2 peripherals */
> -	rc = regmap_write(chip->regmap,
> -			 (PM8008_GPIO1_ADDR | INT_SET_TYPE_OFFSET), BIT(0));
> +	rc = regmap_write(regmap, (PM8008_GPIO1_ADDR | INT_SET_TYPE_OFFSET), BIT(0));
>   	if (rc)
>   		return rc;
>   
> -	rc = regmap_write(chip->regmap,
> -			 (PM8008_GPIO2_ADDR | INT_SET_TYPE_OFFSET), BIT(0));
> +	rc = regmap_write(regmap, (PM8008_GPIO2_ADDR | INT_SET_TYPE_OFFSET), BIT(0));
>   
>   	return rc;
>   }
>   
> -static int pm8008_probe_irq_peripherals(struct pm8008_data *chip,
> +static int pm8008_probe_irq_peripherals(struct device *dev,
> +					struct regmap *regmap,
>   					int client_irq)
>   {
>   	int rc, i;
>   	struct regmap_irq_type *type;
>   	struct regmap_irq_chip_data *irq_data;
>   
> -	rc = pm8008_init(chip);
> +	rc = pm8008_init(regmap);
>   	if (rc) {
> -		dev_err(chip->dev, "Init failed: %d\n", rc);
> +		dev_err(dev, "Init failed: %d\n", rc);
>   		return rc;
>   	}
>   
> @@ -207,10 +197,10 @@ static int pm8008_probe_irq_peripherals(struct pm8008_data *chip,
>   				IRQ_TYPE_LEVEL_HIGH | IRQ_TYPE_LEVEL_LOW);
>   	}
>   
> -	rc = devm_regmap_add_irq_chip(chip->dev, chip->regmap, client_irq,
> +	rc = devm_regmap_add_irq_chip(dev, regmap, client_irq,
>   			IRQF_SHARED, 0, &pm8008_irq_chip, &irq_data);
>   	if (rc) {
> -		dev_err(chip->dev, "Failed to add IRQ chip: %d\n", rc);
> +		dev_err(dev, "Failed to add IRQ chip: %d\n", rc);
>   		return rc;
>   	}
>   
> @@ -220,26 +210,23 @@ static int pm8008_probe_irq_peripherals(struct pm8008_data *chip,
>   static int pm8008_probe(struct i2c_client *client)
>   {
>   	int rc;
> -	struct pm8008_data *chip;
> -
> -	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
> -	if (!chip)
> -		return -ENOMEM;
> +	struct device *dev;
> +	struct regmap *regmap;
>   
> -	chip->dev = &client->dev;
> -	chip->regmap = devm_regmap_init_i2c(client, &qcom_mfd_regmap_cfg);
> -	if (!chip->regmap)
> +	dev = &client->dev;
> +	regmap = devm_regmap_init_i2c(client, &qcom_mfd_regmap_cfg);
> +	if (!regmap)
>   		return -ENODEV;
>   
> -	i2c_set_clientdata(client, chip);
> +	i2c_set_clientdata(client, regmap);
>   
> -	if (of_property_read_bool(chip->dev->of_node, "interrupt-controller")) {
> -		rc = pm8008_probe_irq_peripherals(chip, client->irq);
> +	if (of_property_read_bool(dev->of_node, "interrupt-controller")) {
> +		rc = pm8008_probe_irq_peripherals(dev, regmap, client->irq);
>   		if (rc)
> -			dev_err(chip->dev, "Failed to probe irq periphs: %d\n", rc);
> +			dev_err(dev, "Failed to probe irq periphs: %d\n", rc);
>   	}
>   
> -	return devm_of_platform_populate(chip->dev);
> +	return devm_of_platform_populate(dev);
>   }
>   
>   static const struct of_device_id pm8008_match[] = {
>