[PATCH 0/3] hwmon: (lm75) Add regulator support

[PATCH 0/3] hwmon: (lm75) Add regulator support

[Alban Bedel]

Hi everybody,

this small series add regulator support to the lm75 driver for boards
that don't always power such a sensor. While at it also convert the
DT bindings to yaml.

Alban Bedel (3):
  dt-bindings: hwmon: Convert lm75 bindings to yaml
  dt-bindings: hwmon: Add the +vs supply to the lm75 bindings
  hwmon: (lm75) Add regulator support

 .../devicetree/bindings/hwmon/lm75.txt        | 39 ------------
 .../devicetree/bindings/hwmon/lm75.yaml       | 60 +++++++++++++++++++
 drivers/hwmon/lm75.c                          | 31 +++++++++-
 3 files changed, 89 insertions(+), 41 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/hwmon/lm75.txt
 create mode 100644 Documentation/devicetree/bindings/hwmon/lm75.yaml

-- 
2.25.1

[PATCH 1/3] dt-bindings: hwmon: Convert lm75 bindings to yaml

[Alban Bedel]

In order to automate the verification of DT nodes convert lm75.txt to
lm75.yaml.

Signed-off-by: Alban Bedel <alban.bedel@aerq.com>
---
 .../devicetree/bindings/hwmon/lm75.txt        | 39 -------------
 .../devicetree/bindings/hwmon/lm75.yaml       | 55 +++++++++++++++++++
 2 files changed, 55 insertions(+), 39 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/hwmon/lm75.txt
 create mode 100644 Documentation/devicetree/bindings/hwmon/lm75.yaml

diff --git a/Documentation/devicetree/bindings/hwmon/lm75.txt b/Documentation/devicetree/bindings/hwmon/lm75.txt
deleted file mode 100644
index 273616702c51..000000000000
--- a/Documentation/devicetree/bindings/hwmon/lm75.txt
+++ /dev/null
@@ -1,39 +0,0 @@
-*LM75 hwmon sensor.
-
-Required properties:
-- compatible: manufacturer and chip name, one of
-		"adi,adt75",
-		"dallas,ds1775",
-		"dallas,ds75",
-		"dallas,ds7505",
-		"gmt,g751",
-		"national,lm75",
-		"national,lm75a",
-		"national,lm75b",
-		"maxim,max6625",
-		"maxim,max6626",
-		"maxim,max31725",
-		"maxim,max31726",
-		"maxim,mcp980x",
-		"nxp,pct2075",
-		"st,stds75",
-		"st,stlm75",
-		"microchip,tcn75",
-		"ti,tmp100",
-		"ti,tmp101",
-		"ti,tmp105",
-		"ti,tmp112",
-		"ti,tmp175",
-		"ti,tmp275",
-		"ti,tmp75",
-		"ti,tmp75b",
-		"ti,tmp75c",
-
-- reg: I2C bus address of the device
-
-Example:
-
-sensor@48 {
-	compatible = "st,stlm75";
-	reg = <0x48>;
-};
diff --git a/Documentation/devicetree/bindings/hwmon/lm75.yaml b/Documentation/devicetree/bindings/hwmon/lm75.yaml
new file mode 100644
index 000000000000..78d6291fcdcc
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/lm75.yaml
@@ -0,0 +1,55 @@
+# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/lm75.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: LM75 hwmon sensor
+
+maintainers:
+  - Jean Delvare <jdelvare@suse.com>
+  - Guenter Roeck <linux@roeck-us.net>
+
+properties:
+  compatible:
+    enum:
+      - adi,adt75
+      - dallas,ds1775
+      - dallas,ds75
+      - dallas,ds7505
+      - gmt,g751
+      - national,lm75
+      - national,lm75a
+      - national,lm75b
+      - maxim,max6625
+      - maxim,max6626
+      - maxim,max31725
+      - maxim,max31726
+      - maxim,mcp980x
+      - nxp,pct2075
+      - st,stds75
+      - st,stlm75
+      - microchip,tcn75
+      - ti,tmp100
+      - ti,tmp101
+      - ti,tmp105
+      - ti,tmp112
+      - ti,tmp175
+      - ti,tmp275
+      - ti,tmp75
+      - ti,tmp75b
+      - ti,tmp75c
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+examples:
+  - |
+    sensor@48 {
+            compatible = "st,stlm75";
+            reg = <0x48>;
+    };
-- 
2.25.1

[PATCH 2/3] dt-bindings: hwmon: Add the +vs supply to the lm75 bindings

[Alban Bedel]

Some boards might have a regulator that control the +VS supply, add it
to the bindings.

Signed-off-by: Alban Bedel <alban.bedel@aerq.com>
---
 Documentation/devicetree/bindings/hwmon/lm75.yaml | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/hwmon/lm75.yaml b/Documentation/devicetree/bindings/hwmon/lm75.yaml
index 78d6291fcdcc..1a4405b17924 100644
--- a/Documentation/devicetree/bindings/hwmon/lm75.yaml
+++ b/Documentation/devicetree/bindings/hwmon/lm75.yaml
@@ -43,6 +43,10 @@ properties:
   reg:
     maxItems: 1
 
+  vs-supply:
+    maxItems: 1
+    description: phandle to the regulator that provides the +VS supply
+
 required:
   - compatible
   - reg
@@ -52,4 +56,5 @@ examples:
     sensor@48 {
             compatible = "st,stlm75";
             reg = <0x48>;
+            vs-supply = <&vs>;
     };
-- 
2.25.1

[PATCH 3/3] hwmon: (lm75) Add regulator support

[Alban Bedel]

Add regulator support for boards where the sensor first need to be
powered up before it can be used.

Signed-off-by: Alban Bedel <alban.bedel@aerq.com>
---
 drivers/hwmon/lm75.c | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index ba0be48aeadd..b673f8d2ef20 100644
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -17,6 +17,7 @@
 #include <linux/of.h>
 #include <linux/regmap.h>
 #include <linux/util_macros.h>
+#include <linux/regulator/consumer.h>
 #include "lm75.h"
 
 /*
@@ -101,6 +102,7 @@ static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
 struct lm75_data {
 	struct i2c_client		*client;
 	struct regmap			*regmap;
+	struct regulator		*vs;
 	u8				orig_conf;
 	u8				current_conf;
 	u8				resolution;	/* In bits, 9 to 16 */
@@ -540,6 +542,8 @@ static void lm75_remove(void *data)
 	struct i2c_client *client = lm75->client;
 
 	i2c_smbus_write_byte_data(client, LM75_REG_CONF, lm75->orig_conf);
+	if (lm75->vs)
+		regulator_disable(lm75->vs);
 }
 
 static int
@@ -567,6 +571,14 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	data->client = client;
 	data->kind = kind;
 
+	data->vs = devm_regulator_get_optional(dev, "vs");
+	if (IS_ERR(data->vs)) {
+		if (PTR_ERR(data->vs) == -ENODEV)
+			data->vs = NULL;
+		else
+			return PTR_ERR(data->vs);
+	}
+
 	data->regmap = devm_regmap_init_i2c(client, &lm75_regmap_config);
 	if (IS_ERR(data->regmap))
 		return PTR_ERR(data->regmap);
@@ -581,11 +593,21 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	data->sample_time = data->params->default_sample_time;
 	data->resolution = data->params->default_resolution;
 
+	/* Enable the power */
+	if (data->vs) {
+		err = regulator_enable(data->vs);
+		if (err) {
+			dev_err(dev, "failed to enable regulator: %d\n", err);
+			return err;
+		}
+	}
+
 	/* Cache original configuration */
 	status = i2c_smbus_read_byte_data(client, LM75_REG_CONF);
 	if (status < 0) {
 		dev_dbg(dev, "Can't read config? %d\n", status);
-		return status;
+		err = status;
+		goto disable_regulator;
 	}
 	data->orig_conf = status;
 	data->current_conf = status;
@@ -593,7 +615,7 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	err = lm75_write_config(data, data->params->set_mask,
 				data->params->clr_mask);
 	if (err)
-		return err;
+		goto disable_regulator;
 
 	err = devm_add_action_or_reset(dev, lm75_remove, data);
 	if (err)
@@ -608,6 +630,11 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	dev_info(dev, "%s: sensor '%s'\n", dev_name(hwmon_dev), client->name);
 
 	return 0;
+
+disable_regulator:
+	if (data->vs)
+		regulator_disable(data->vs);
+	return err;
 }
 
 static const struct i2c_device_id lm75_ids[] = {
-- 
2.25.1

Re: [PATCH 3/3] hwmon: (lm75) Add regulator support

[Mark Brown]

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On Thu, Sep 17, 2020 at 12:18:19PM +0200, Alban Bedel wrote:

> +	data->vs = devm_regulator_get_optional(dev, "vs");
> +	if (IS_ERR(data->vs)) {

Unless the device can work without power you should not be using
regulator_get_optional().

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Re: [PATCH 3/3] hwmon: (lm75) Add regulator support

[Guenter Roeck]

[-- Attachment #1.1: Type: text/plain, Size: 390 bytes --]

On 9/17/20 4:00 AM, Mark Brown wrote:
> On Thu, Sep 17, 2020 at 12:18:19PM +0200, Alban Bedel wrote:
> 
>> +	data->vs = devm_regulator_get_optional(dev, "vs");
>> +	if (IS_ERR(data->vs)) {
> 
> Unless the device can work without power you should not be using
> regulator_get_optional().
> 

The driver works today without regulator, and needs to continue
doing so.

Guenter


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Re: [PATCH 3/3] hwmon: (lm75) Add regulator support

[Guenter Roeck]

On 9/17/20 3:18 AM, Alban Bedel wrote:
> Add regulator support for boards where the sensor first need to be
> powered up before it can be used.
> 
> Signed-off-by: Alban Bedel <alban.bedel@aerq.com>
> ---
>  drivers/hwmon/lm75.c | 31 +++++++++++++++++++++++++++++--
>  1 file changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
> index ba0be48aeadd..b673f8d2ef20 100644
> --- a/drivers/hwmon/lm75.c
> +++ b/drivers/hwmon/lm75.c
> @@ -17,6 +17,7 @@
>  #include <linux/of.h>
>  #include <linux/regmap.h>
>  #include <linux/util_macros.h>
> +#include <linux/regulator/consumer.h>
>  #include "lm75.h"
>  
>  /*
> @@ -101,6 +102,7 @@ static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
>  struct lm75_data {
>  	struct i2c_client		*client;
>  	struct regmap			*regmap;
> +	struct regulator		*vs;
>  	u8				orig_conf;
>  	u8				current_conf;
>  	u8				resolution;	/* In bits, 9 to 16 */
> @@ -540,6 +542,8 @@ static void lm75_remove(void *data)
>  	struct i2c_client *client = lm75->client;
>  
>  	i2c_smbus_write_byte_data(client, LM75_REG_CONF, lm75->orig_conf);
> +	if (lm75->vs)
> +		regulator_disable(lm75->vs);
>  }
>  
>  static int
> @@ -567,6 +571,14 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  	data->client = client;
>  	data->kind = kind;
>  
> +	data->vs = devm_regulator_get_optional(dev, "vs");

Looking into the regulator API, it may be better if you use devm_regulator_get().
AFAICS it returns a dummy regulator if there is none, and NULL if the regulator
subsystem is disabled. So
	data->vs = devm_regulator_get(dev, "vs");
	if (IS_ERR(data->vs))
		return PTR_ERR(data->vs);
should work and would be less messy.

> +	if (IS_ERR(data->vs)) {
> +		if (PTR_ERR(data->vs) == -ENODEV)
> +			data->vs = NULL;
> +		else
> +			return PTR_ERR(data->vs);
> +	}
> +
>  	data->regmap = devm_regmap_init_i2c(client, &lm75_regmap_config);
>  	if (IS_ERR(data->regmap))
>  		return PTR_ERR(data->regmap);
> @@ -581,11 +593,21 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  	data->sample_time = data->params->default_sample_time;
>  	data->resolution = data->params->default_resolution;
>  
> +	/* Enable the power */
> +	if (data->vs) {
> +		err = regulator_enable(data->vs);
> +		if (err) {
> +			dev_err(dev, "failed to enable regulator: %d\n", err);
> +			return err;
> +		}
> +	}
> +

How about device removal ? Don't you have to call regulator_disable()
there as well ? If so, it might be best to use devm_add_action_or_reset()
to register a disable function.

Thanks,
Guenter

>  	/* Cache original configuration */
>  	status = i2c_smbus_read_byte_data(client, LM75_REG_CONF);
>  	if (status < 0) {
>  		dev_dbg(dev, "Can't read config? %d\n", status);
> -		return status;
> +		err = status;
> +		goto disable_regulator;
>  	}
>  	data->orig_conf = status;
>  	data->current_conf = status;
> @@ -593,7 +615,7 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  	err = lm75_write_config(data, data->params->set_mask,
>  				data->params->clr_mask);
>  	if (err)
> -		return err;
> +		goto disable_regulator;
>  
>  	err = devm_add_action_or_reset(dev, lm75_remove, data);
>  	if (err)
> @@ -608,6 +630,11 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  	dev_info(dev, "%s: sensor '%s'\n", dev_name(hwmon_dev), client->name);
>  
>  	return 0;
> +
> +disable_regulator:
> +	if (data->vs)
> +		regulator_disable(data->vs);
> +	return err;
>  }
>  
>  static const struct i2c_device_id lm75_ids[] = {
> 

Re: [PATCH 3/3] hwmon: (lm75) Add regulator support

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 598 bytes --]

On Thu, Sep 17, 2020 at 07:04:51PM -0700, Guenter Roeck wrote:
> On 9/17/20 4:00 AM, Mark Brown wrote:
> > On Thu, Sep 17, 2020 at 12:18:19PM +0200, Alban Bedel wrote:

> >> +	data->vs = devm_regulator_get_optional(dev, "vs");
> >> +	if (IS_ERR(data->vs)) {

> > Unless the device can work without power you should not be using
> > regulator_get_optional().

> The driver works today without regulator, and needs to continue
> doing so.

And it will continue to do so if it uses the normal regulator API, it
will as ever ensure that if no regulator is provided by the firmware a
dummy is provided.

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Re: [PATCH 3/3] hwmon: (lm75) Add regulator support

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 464 bytes --]

On Thu, Sep 17, 2020 at 10:33:37PM -0700, Guenter Roeck wrote:
> On 9/17/20 3:18 AM, Alban Bedel wrote:

> > +		err = regulator_enable(data->vs);

> How about device removal ? Don't you have to call regulator_disable()
> there as well ? If so, it might be best to use devm_add_action_or_reset()
> to register a disable function.

Yes, disables should be balanced (and any attempt to unregister the
regulator with references still held should result in a warning).

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Re: [PATCH 1/3] dt-bindings: hwmon: Convert lm75 bindings to yaml

[Rob Herring]

On Thu, 17 Sep 2020 12:18:17 +0200, Alban Bedel wrote:
> In order to automate the verification of DT nodes convert lm75.txt to
> lm75.yaml.
> 
> Signed-off-by: Alban Bedel <alban.bedel@aerq.com>
> ---
>  .../devicetree/bindings/hwmon/lm75.txt        | 39 -------------
>  .../devicetree/bindings/hwmon/lm75.yaml       | 55 +++++++++++++++++++
>  2 files changed, 55 insertions(+), 39 deletions(-)
>  delete mode 100644 Documentation/devicetree/bindings/hwmon/lm75.txt
>  create mode 100644 Documentation/devicetree/bindings/hwmon/lm75.yaml
> 


My bot found errors running 'make dt_binding_check' on your patch:

Documentation/devicetree/bindings/hwmon/lm75.example.dts:21.17-30: Warning (reg_format): /example-0/sensor@48:reg: property has invalid length (4 bytes) (#address-cells == 1, #size-cells == 1)
Documentation/devicetree/bindings/hwmon/lm75.example.dt.yaml: Warning (pci_device_reg): Failed prerequisite 'reg_format'
Documentation/devicetree/bindings/hwmon/lm75.example.dt.yaml: Warning (pci_device_bus_num): Failed prerequisite 'reg_format'
Documentation/devicetree/bindings/hwmon/lm75.example.dt.yaml: Warning (simple_bus_reg): Failed prerequisite 'reg_format'
Documentation/devicetree/bindings/hwmon/lm75.example.dt.yaml: Warning (i2c_bus_reg): Failed prerequisite 'reg_format'
Documentation/devicetree/bindings/hwmon/lm75.example.dt.yaml: Warning (spi_bus_reg): Failed prerequisite 'reg_format'
/builds/robherring/linux-dt-review/Documentation/devicetree/bindings/hwmon/lm75.example.dt.yaml: example-0: sensor@48:reg:0: [72] is too short
	From schema: /usr/local/lib/python3.8/dist-packages/dtschema/schemas/reg.yaml


See https://patchwork.ozlabs.org/patch/1366031

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure dt-schema is up to date:

pip3 install git+https://github.com/devicetree-org/dt-schema.git@master --upgrade

Please check and re-submit.

Re: [PATCH 2/3] dt-bindings: hwmon: Add the +vs supply to the lm75 bindings

[Rob Herring]

On Thu, Sep 17, 2020 at 12:18:18PM +0200, Alban Bedel wrote:
> Some boards might have a regulator that control the +VS supply, add it
> to the bindings.
> 
> Signed-off-by: Alban Bedel <alban.bedel@aerq.com>
> ---
>  Documentation/devicetree/bindings/hwmon/lm75.yaml | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/lm75.yaml b/Documentation/devicetree/bindings/hwmon/lm75.yaml
> index 78d6291fcdcc..1a4405b17924 100644
> --- a/Documentation/devicetree/bindings/hwmon/lm75.yaml
> +++ b/Documentation/devicetree/bindings/hwmon/lm75.yaml
> @@ -43,6 +43,10 @@ properties:
>    reg:
>      maxItems: 1
>  
> +  vs-supply:
> +    maxItems: 1

*-supply is always 1, so drop.

> +    description: phandle to the regulator that provides the +VS supply
> +
>  required:
>    - compatible
>    - reg
> @@ -52,4 +56,5 @@ examples:
>      sensor@48 {
>              compatible = "st,stlm75";
>              reg = <0x48>;
> +            vs-supply = <&vs>;
>      };
> -- 
> 2.25.1
> 

Re: [PATCH 3/3] hwmon: (lm75) Add regulator support

[Bedel, Alban]

[-- Attachment #1: Type: text/plain, Size: 3059 bytes --]

On Thu, 2020-09-17 at 22:33 -0700, Guenter Roeck wrote:
> On 9/17/20 3:18 AM, Alban Bedel wrote:
> > Add regulator support for boards where the sensor first need to be
> > powered up before it can be used.
> > 
> > Signed-off-by: Alban Bedel <alban.bedel@aerq.com>
> > ---
> >  drivers/hwmon/lm75.c | 31 +++++++++++++++++++++++++++++--
> >  1 file changed, 29 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
> > index ba0be48aeadd..b673f8d2ef20 100644
> > --- a/drivers/hwmon/lm75.c
> > +++ b/drivers/hwmon/lm75.c
> > @@ -17,6 +17,7 @@
> >  #include <linux/of.h>
> >  #include <linux/regmap.h>
> >  #include <linux/util_macros.h>
> > +#include <linux/regulator/consumer.h>
> >  #include "lm75.h"
> >  
> >  /*
> > @@ -101,6 +102,7 @@ static const unsigned short normal_i2c[] = {
> > 0x48, 0x49, 0x4a, 0x4b, 0x4c,
> >  struct lm75_data {
> >  	struct i2c_client		*client;
> >  	struct regmap			*regmap;
> > +	struct regulator		*vs;
> >  	u8				orig_conf;
> >  	u8				current_conf;
> >  	u8				resolution;	/* In bits, 9 to 16 */
> > @@ -540,6 +542,8 @@ static void lm75_remove(void *data)
> >  	struct i2c_client *client = lm75->client;
> >  
> >  	i2c_smbus_write_byte_data(client, LM75_REG_CONF, lm75->orig_conf);
> > +	if (lm75->vs)
> > +		regulator_disable(lm75->vs);
> >  }
> >  
> >  static int
> > @@ -567,6 +571,14 @@ lm75_probe(struct i2c_client *client, const
> > struct i2c_device_id *id)
> >  	data->client = client;
> >  	data->kind = kind;
> >  
> > +	data->vs = devm_regulator_get_optional(dev, "vs");
> 
> Looking into the regulator API, it may be better if you use
> devm_regulator_get().
> AFAICS it returns a dummy regulator if there is none, and NULL if the
> regulator subsystem is disabled. So
> 	data->vs = devm_regulator_get(dev, "vs");
> 	if (IS_ERR(data->vs))
> 		return PTR_ERR(data->vs);
> should work and would be less messy.

Ok, I'll change that in the next version.

> > +	if (IS_ERR(data->vs)) {
> > +		if (PTR_ERR(data->vs) == -ENODEV)
> > +			data->vs = NULL;
> > +		else
> > +			return PTR_ERR(data->vs);
> > +	}
> > +
> >  	data->regmap = devm_regmap_init_i2c(client,
> > &lm75_regmap_config);
> >  	if (IS_ERR(data->regmap))
> >  		return PTR_ERR(data->regmap);
> > @@ -581,11 +593,21 @@ lm75_probe(struct i2c_client *client, const
> > struct i2c_device_id *id)
> >  	data->sample_time = data->params->default_sample_time;
> >  	data->resolution = data->params->default_resolution;
> >  
> > +	/* Enable the power */
> > +	if (data->vs) {
> > +		err = regulator_enable(data->vs);
> > +		if (err) {
> > +			dev_err(dev, "failed to enable regulator:
> > %d\n", err);
> > +			return err;
> > +		}
> > +	}
> > +
> 
> How about device removal ? Don't you have to call regulator_disable()
> there as well ? If so, it might be best to use
> devm_add_action_or_reset() to register a disable function.

This is handled in lm75_remove() where I added the regulator_disable()
call.

Alban



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Re: [PATCH 3/3] hwmon: (lm75) Add regulator support

[Guenter Roeck]

On Mon, Sep 28, 2020 at 03:13:53PM +0000, Bedel, Alban wrote:
> On Thu, 2020-09-17 at 22:33 -0700, Guenter Roeck wrote:
> > On 9/17/20 3:18 AM, Alban Bedel wrote:
> > > Add regulator support for boards where the sensor first need to be
> > > powered up before it can be used.
> > > 
> > > Signed-off-by: Alban Bedel <alban.bedel@aerq.com>
> > > ---
> > >  drivers/hwmon/lm75.c | 31 +++++++++++++++++++++++++++++--
> > >  1 file changed, 29 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
> > > index ba0be48aeadd..b673f8d2ef20 100644
> > > --- a/drivers/hwmon/lm75.c
> > > +++ b/drivers/hwmon/lm75.c
> > > @@ -17,6 +17,7 @@
> > >  #include <linux/of.h>
> > >  #include <linux/regmap.h>
> > >  #include <linux/util_macros.h>
> > > +#include <linux/regulator/consumer.h>
> > >  #include "lm75.h"
> > >  
> > >  /*
> > > @@ -101,6 +102,7 @@ static const unsigned short normal_i2c[] = {
> > > 0x48, 0x49, 0x4a, 0x4b, 0x4c,
> > >  struct lm75_data {
> > >  	struct i2c_client		*client;
> > >  	struct regmap			*regmap;
> > > +	struct regulator		*vs;
> > >  	u8				orig_conf;
> > >  	u8				current_conf;
> > >  	u8				resolution;	/* In bits, 9 to 16 */
> > > @@ -540,6 +542,8 @@ static void lm75_remove(void *data)
> > >  	struct i2c_client *client = lm75->client;
> > >  
> > >  	i2c_smbus_write_byte_data(client, LM75_REG_CONF, lm75->orig_conf);
> > > +	if (lm75->vs)
> > > +		regulator_disable(lm75->vs);
> > >  }
> > >  
> > >  static int
> > > @@ -567,6 +571,14 @@ lm75_probe(struct i2c_client *client, const
> > > struct i2c_device_id *id)
> > >  	data->client = client;
> > >  	data->kind = kind;
> > >  
> > > +	data->vs = devm_regulator_get_optional(dev, "vs");
> > 
> > Looking into the regulator API, it may be better if you use
> > devm_regulator_get().
> > AFAICS it returns a dummy regulator if there is none, and NULL if the
> > regulator subsystem is disabled. So
> > 	data->vs = devm_regulator_get(dev, "vs");
> > 	if (IS_ERR(data->vs))
> > 		return PTR_ERR(data->vs);
> > should work and would be less messy.
> 
> Ok, I'll change that in the next version.
> 
> > > +	if (IS_ERR(data->vs)) {
> > > +		if (PTR_ERR(data->vs) == -ENODEV)
> > > +			data->vs = NULL;
> > > +		else
> > > +			return PTR_ERR(data->vs);
> > > +	}
> > > +
> > >  	data->regmap = devm_regmap_init_i2c(client,
> > > &lm75_regmap_config);
> > >  	if (IS_ERR(data->regmap))
> > >  		return PTR_ERR(data->regmap);
> > > @@ -581,11 +593,21 @@ lm75_probe(struct i2c_client *client, const
> > > struct i2c_device_id *id)
> > >  	data->sample_time = data->params->default_sample_time;
> > >  	data->resolution = data->params->default_resolution;
> > >  
> > > +	/* Enable the power */
> > > +	if (data->vs) {
> > > +		err = regulator_enable(data->vs);
> > > +		if (err) {
> > > +			dev_err(dev, "failed to enable regulator:
> > > %d\n", err);
> > > +			return err;
> > > +		}
> > > +	}
> > > +
> > 
> > How about device removal ? Don't you have to call regulator_disable()
> > there as well ? If so, it might be best to use
> > devm_add_action_or_reset() to register a disable function.
> 
> This is handled in lm75_remove() where I added the regulator_disable()
> call.

lm75_remove() won't be called if the probe function fails.

Guenter

Re: [PATCH 3/3] hwmon: (lm75) Add regulator support

[Guenter Roeck]

On Mon, Sep 28, 2020 at 09:29:49AM -0700, Guenter Roeck wrote:
> > 
> > This is handled in lm75_remove() where I added the regulator_disable()
> > call.
> 
> lm75_remove() won't be called if the probe function fails.
> 
Sorry, I am confused; please ignore this noise.

Guenter