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Message-ID: <4112b5af-15de-007c-fcc2-c31ce9f9e426@quicinc.com>
Date:   Wed, 29 Jun 2022 16:06:54 +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>
 <a1c6e3c9-962d-411e-7fbf-9e760e9dc8c0@quicinc.com>
 <Yrqw1YRyCGG+d4GL@google.com>
From:   "Satya Priya Kakitapalli (Temp)" <quic_c_skakit@quicinc.com>
In-Reply-To: <Yrqw1YRyCGG+d4GL@google.com>
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On 6/28/2022 1:12 PM, Lee Jones wrote:
> On Tue, 28 Jun 2022, Satya Priya Kakitapalli (Temp) wrote:
>
>> 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?
> Look down ...
>
>>> 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);
> Here ^


I have added a dummy device and set the client data by passing regmap, 
see below:

+       regulators_client = i2c_new_dummy_device(client->adapter, 
client->addr + 1);
+       if (IS_ERR(regulators_client)) {
+               dev_err(dev, "can't attach client\n");
+               return PTR_ERR(regulators_client);
+       }
+
+       regulators_regmap = devm_regmap_init_i2c(regulators_client, 
&qcom_mfd_regmap_cfg[1]);
+       if (!regmap)
+               return -ENODEV;
+
+       i2c_set_clientdata(client, regulators_regmap);

Now if i try to get this regmap from regulator driver by doing

struct regmap *regmap = dev_get_drvdata(pdev->dev.parent);

it still gets me the regmap of pm8008@8 device and not the regulator 
device regmap (0x9). Not sure if I'm missing something here.


>>> -	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[] = {
>>>