[PATCH 1/2] hwmon: ntc: Add DT support to NTC thermistor driver

[PATCH 1/2] hwmon: ntc: Add DT support to NTC thermistor driver

[Naveen Krishna Chatradhi]

This patch adds the DT support to NTC driver to parse the
platform data.

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
---
 drivers/hwmon/ntc_thermistor.c |   93 ++++++++++++++++++++++++++++++++--------
 1 file changed, 75 insertions(+), 18 deletions(-)

diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
index d92b237..cfedbd3 100644
--- a/drivers/hwmon/ntc_thermistor.c
+++ b/drivers/hwmon/ntc_thermistor.c
@@ -26,6 +26,7 @@
 #include <linux/math64.h>
 #include <linux/platform_device.h>
 #include <linux/err.h>
+#include <linux/of.h>
 
 #include <linux/platform_data/ntc_thermistor.h>
 
@@ -37,6 +38,41 @@ struct ntc_compensation {
 	unsigned int	ohm;
 };
 
+static const struct platform_device_id ntc_thermistor_id[] = {
+	{ "ncp15wb473", TYPE_NCPXXWB473 },
+	{ "ncp18wb473", TYPE_NCPXXWB473 },
+	{ "ncp21wb473", TYPE_NCPXXWB473 },
+	{ "ncp03wb473", TYPE_NCPXXWB473 },
+	{ "ncp15wl333", TYPE_NCPXXWL333 },
+	{ },
+};
+
+#ifdef CONFIG_OF
+static const struct of_device_id ntc_match[] = {
+	{ .compatible = "ntc,ncp15wb473", .data = (void *)TYPE_NCPXXWB473 },
+	{ .compatible = "ntc,ncp18wb473", .data = (void *)TYPE_NCPXXWB473 },
+	{ .compatible = "ntc,ncp21wb473", .data = (void *)TYPE_NCPXXWB473 },
+	{ .compatible = "ntc,ncp03wb473", .data = (void *)TYPE_NCPXXWB473 },
+	{ .compatible = "ntc,ncp15wl333", .data = (void *)TYPE_NCPXXWL333 },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ntc_match);
+#endif
+
+/* Get NTC type either from device tree or platform data. */
+static enum ntc_thermistor_type thermistor_get_type
+				(struct platform_device *pdev)
+{
+	if (pdev->dev.of_node) {
+		const struct of_device_id *match;
+		match = of_match_node(of_match_ptr(ntc_match),
+						pdev->dev.of_node);
+		return (unsigned int)match->data;
+	}
+
+	return platform_get_device_id(pdev)->driver_data;
+}
+
 /*
  * A compensation table should be sorted by the values of .ohm
  * in descending order.
@@ -126,6 +162,27 @@ struct ntc_data {
 	char name[PLATFORM_NAME_SIZE];
 };
 
+#ifdef CONFIG_OF
+static void ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata,
+							struct device_node *np)
+{
+	of_property_read_u32(np, "pullup-uV", &pdata->pullup_uV);
+	of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm);
+	of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm);
+	if (of_find_property(np, "connected-positive", NULL))
+		pdata->connect = NTC_CONNECTED_POSITIVE;
+	else /* status change should be possible if not always on. */
+		pdata->connect = NTC_CONNECTED_GROUND;
+}
+#else
+static void
+static void ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata,
+							struct device_node *np)
+{
+	return;
+}
+#endif
+
 static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
 {
 	if (divisor == 0 && dividend == 0)
@@ -313,9 +370,19 @@ static const struct attribute_group ntc_attr_group = {
 static int ntc_thermistor_probe(struct platform_device *pdev)
 {
 	struct ntc_data *data;
-	struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data;
+	struct device_node *np = pdev->dev.of_node;
+	struct ntc_thermistor_platform_data *pdata = NULL;
 	int ret = 0;
 
+	if (np) {
+		pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+		if (!pdata)
+			return -ENOMEM;
+
+		ntc_thermistor_parse_dt(pdata, np);
+	} else
+		pdata = pdev->dev.platform_data;
+
 	if (!pdata) {
 		dev_err(&pdev->dev, "No platform init data supplied.\n");
 		return -ENODEV;
@@ -353,9 +420,9 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
 	data->dev = &pdev->dev;
 	data->pdev = pdev;
 	data->pdata = pdata;
-	strlcpy(data->name, pdev->id_entry->name, sizeof(data->name));
+	strncpy(data->name, dev_name(&pdev->dev), PLATFORM_NAME_SIZE);
 
-	switch (pdev->id_entry->driver_data) {
+	switch (thermistor_get_type(pdev)) {
 	case TYPE_NCPXXWB473:
 		data->comp = ncpXXwb473;
 		data->n_comp = ARRAY_SIZE(ncpXXwb473);
@@ -365,9 +432,8 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
 		data->n_comp = ARRAY_SIZE(ncpXXwl333);
 		break;
 	default:
-		dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
-				pdev->id_entry->driver_data,
-				pdev->id_entry->name);
+		dev_err(&pdev->dev, "Unknown device type: %u\n",
+				thermistor_get_type(pdev));
 		return -EINVAL;
 	}
 
@@ -386,9 +452,8 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
 		goto err_after_sysfs;
 	}
 
-	dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n",
-			pdev->name, pdev->id, pdev->id_entry->name,
-			pdev->id_entry->driver_data);
+	dev_info(&pdev->dev, "Thermistor successfully probed.\n");
+
 	return 0;
 err_after_sysfs:
 	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
@@ -406,19 +471,11 @@ static int ntc_thermistor_remove(struct platform_device *pdev)
 	return 0;
 }
 
-static const struct platform_device_id ntc_thermistor_id[] = {
-	{ "ncp15wb473", TYPE_NCPXXWB473 },
-	{ "ncp18wb473", TYPE_NCPXXWB473 },
-	{ "ncp21wb473", TYPE_NCPXXWB473 },
-	{ "ncp03wb473", TYPE_NCPXXWB473 },
-	{ "ncp15wl333", TYPE_NCPXXWL333 },
-	{ },
-};
-
 static struct platform_driver ntc_thermistor_driver = {
 	.driver = {
 		.name = "ntc-thermistor",
 		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(ntc_match),
 	},
 	.probe = ntc_thermistor_probe,
 	.remove = ntc_thermistor_remove,
-- 
1.7.9.5

[PATCH 2/2] hwmon: NTC: add IIO get channel and read support

[Naveen Krishna Chatradhi]

This patch adds the support to work as a iio device.
iio_get_channel and iio_raw_read works.

During the probe ntc driver gets the respective channels of ADC
and uses iio_raw_read calls to get the ADC converted value.

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
---

Still not sure about the read_uV function parameter change and placement.

There were a few CamelCase warnings during checkpatch run.
I can clean them if anyone insists.

 drivers/hwmon/ntc_thermistor.c               |   36 +++++++++++++++++++++++++-
 include/linux/platform_data/ntc_thermistor.h |    7 ++++-
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
index cfedbd3..1d31260 100644
--- a/drivers/hwmon/ntc_thermistor.c
+++ b/drivers/hwmon/ntc_thermistor.c
@@ -30,6 +30,11 @@
 
 #include <linux/platform_data/ntc_thermistor.h>
 
+#include <linux/iio/iio.h>
+#include <linux/iio/machine.h>
+#include <linux/iio/driver.h>
+#include <linux/iio/consumer.h>
+
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
 
@@ -162,6 +167,28 @@ struct ntc_data {
 	char name[PLATFORM_NAME_SIZE];
 };
 
+static int ntc_adc_read(struct ntc_thermistor_platform_data *pdata)
+{
+	struct iio_channel *channel = pdata->chan;
+	unsigned int result;
+	int val, ret;
+
+	if (!channel)
+		return -EINVAL;
+
+	ret = iio_read_channel_raw(channel, &val);
+	if (ret < 0) {
+		pr_err("read channel() error: %d\n", ret);
+		return ret;
+	}
+
+	/* unit: mV */
+	result = pdata->pullup_uV * (s64) val;
+	result >>= 12;
+
+	return result;
+}
+
 #ifdef CONFIG_OF
 static void ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata,
 							struct device_node *np)
@@ -173,6 +200,8 @@ static void ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata,
 		pdata->connect = NTC_CONNECTED_POSITIVE;
 	else /* status change should be possible if not always on. */
 		pdata->connect = NTC_CONNECTED_GROUND;
+
+	pdata->read_uV = ntc_adc_read;
 }
 #else
 static void
@@ -317,7 +346,7 @@ static int ntc_thermistor_get_ohm(struct ntc_data *data)
 		return data->pdata->read_ohm(data->pdev);
 
 	if (data->pdata->read_uV) {
-		read_uV = data->pdata->read_uV(data->pdev);
+		read_uV = data->pdata->read_uV(data->pdata);
 		if (read_uV < 0)
 			return read_uV;
 		return get_ohm_of_thermistor(data, read_uV);
@@ -417,6 +446,8 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
 	if (!data)
 		return -ENOMEM;
 
+	pdata->chan = iio_channel_get(&pdev->dev, NULL);
+
 	data->dev = &pdev->dev;
 	data->pdev = pdev;
 	data->pdata = pdata;
@@ -457,15 +488,18 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
 	return 0;
 err_after_sysfs:
 	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
+	iio_channel_release(pdata->chan);
 	return ret;
 }
 
 static int ntc_thermistor_remove(struct platform_device *pdev)
 {
 	struct ntc_data *data = platform_get_drvdata(pdev);
+	struct ntc_thermistor_platform_data *pdata = data->pdata;
 
 	hwmon_device_unregister(data->hwmon_dev);
 	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
+	iio_channel_release(pdata->chan);
 	platform_set_drvdata(pdev, NULL);
 
 	return 0;
diff --git a/include/linux/platform_data/ntc_thermistor.h b/include/linux/platform_data/ntc_thermistor.h
index 18f3c3a..671d056 100644
--- a/include/linux/platform_data/ntc_thermistor.h
+++ b/include/linux/platform_data/ntc_thermistor.h
@@ -34,19 +34,24 @@ struct ntc_thermistor_platform_data {
 	 *
 	 * pullup_uV, pullup_ohm, pulldown_ohm, and connect are required to use
 	 * read_uV()
+	 * takes the platform data structure as the parameter
 	 *
 	 * How to setup pullup_ohm, pulldown_ohm, and connect is
 	 * described at Documentation/hwmon/ntc_thermistor
 	 *
 	 * pullup/down_ohm: 0 for infinite / not-connected
+	 *
+	 * iio_channel to communicate with the ADC which the
+	 * thermistor is using for conversion of the analog values.
 	 */
-	int (*read_uV)(struct platform_device *);
+	int (*read_uV)(struct ntc_thermistor_platform_data *);
 	int (*read_ohm)(struct platform_device *);
 	unsigned int pullup_uV;
 
 	unsigned int pullup_ohm;
 	unsigned int pulldown_ohm;
 	enum { NTC_CONNECTED_POSITIVE, NTC_CONNECTED_GROUND } connect;
+	struct iio_channel *chan;
 };
 
 #endif /* _LINUX_NTC_H */
-- 
1.7.9.5

Re: [PATCH 1/2] hwmon: ntc: Add DT support to NTC thermistor driver

[Guenter Roeck]

On Mon, Mar 11, 2013 at 07:39:46AM +0530, Naveen Krishna Chatradhi wrote:
> This patch adds the DT support to NTC driver to parse the
> platform data.
> 
> Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
> ---
>  drivers/hwmon/ntc_thermistor.c |   93 ++++++++++++++++++++++++++++++++--------
>  1 file changed, 75 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
> index d92b237..cfedbd3 100644
> --- a/drivers/hwmon/ntc_thermistor.c
> +++ b/drivers/hwmon/ntc_thermistor.c
> @@ -26,6 +26,7 @@
>  #include <linux/math64.h>
>  #include <linux/platform_device.h>
>  #include <linux/err.h>
> +#include <linux/of.h>
>  
>  #include <linux/platform_data/ntc_thermistor.h>
>  
> @@ -37,6 +38,41 @@ struct ntc_compensation {
>  	unsigned int	ohm;
>  };
>  
> +static const struct platform_device_id ntc_thermistor_id[] = {
> +	{ "ncp15wb473", TYPE_NCPXXWB473 },
> +	{ "ncp18wb473", TYPE_NCPXXWB473 },
> +	{ "ncp21wb473", TYPE_NCPXXWB473 },
> +	{ "ncp03wb473", TYPE_NCPXXWB473 },
> +	{ "ncp15wl333", TYPE_NCPXXWL333 },
> +	{ },
> +};
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id ntc_match[] = {
> +	{ .compatible = "ntc,ncp15wb473", .data = (void *)TYPE_NCPXXWB473 },
> +	{ .compatible = "ntc,ncp18wb473", .data = (void *)TYPE_NCPXXWB473 },
> +	{ .compatible = "ntc,ncp21wb473", .data = (void *)TYPE_NCPXXWB473 },
> +	{ .compatible = "ntc,ncp03wb473", .data = (void *)TYPE_NCPXXWB473 },
> +	{ .compatible = "ntc,ncp15wl333", .data = (void *)TYPE_NCPXXWL333 },

Better point to ntc_thermistor_id[TYPE_xxx]. See below.

> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, ntc_match);
> +#endif
> +
> +/* Get NTC type either from device tree or platform data. */
> +static enum ntc_thermistor_type thermistor_get_type
> +				(struct platform_device *pdev)
> +{
> +	if (pdev->dev.of_node) {
> +		const struct of_device_id *match;
> +		match = of_match_node(of_match_ptr(ntc_match),
> +						pdev->dev.of_node);
> +		return (unsigned int)match->data;
> +	}
> +
> +	return platform_get_device_id(pdev)->driver_data;
> +}
> +
>  /*
>   * A compensation table should be sorted by the values of .ohm
>   * in descending order.
> @@ -126,6 +162,27 @@ struct ntc_data {
>  	char name[PLATFORM_NAME_SIZE];
>  };
>  
> +#ifdef CONFIG_OF

Please merge the two CONFIG_OF blocks into one.

> +static void ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata,
> +							struct device_node *np)
> +{
> +	of_property_read_u32(np, "pullup-uV", &pdata->pullup_uV);
> +	of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm);
> +	of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm);
> +	if (of_find_property(np, "connected-positive", NULL))
> +		pdata->connect = NTC_CONNECTED_POSITIVE;
> +	else /* status change should be possible if not always on. */
> +		pdata->connect = NTC_CONNECTED_GROUND;
> +}
> +#else
> +static void
> +static void ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata,
> +							struct device_node *np)
> +{
> +	return;

Unnecessary return statement.

> +}
> +#endif
> +
>  static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
>  {
>  	if (divisor == 0 && dividend == 0)
> @@ -313,9 +370,19 @@ static const struct attribute_group ntc_attr_group = {
>  static int ntc_thermistor_probe(struct platform_device *pdev)
>  {
>  	struct ntc_data *data;
> -	struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data;
> +	struct device_node *np = pdev->dev.of_node;
> +	struct ntc_thermistor_platform_data *pdata = NULL;

Unnecessary change. It doesn't hurt if pdata is initialized to non-NULL, and
initializing it to NULL is unnecessary anyway since it is always assigned below.

>  	int ret = 0;
>  
> +	if (np) {
> +		pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
> +		if (!pdata)
> +			return -ENOMEM;
> +
> +		ntc_thermistor_parse_dt(pdata, np);

This compiles, but the resulting code would not work as the necessary fields
in pdata are not all filled out. So I think it would be better to merge the code
with the next patch, as both don't really work independently.

> +	} else
> +		pdata = pdev->dev.platform_data;

Not necessary if you keep above pre-initialization.

A better idea would be to move the devm_kzalloc into ntc_thermistor_parse_dt
and return a pointer to pdata from it. Then you would have

	pdata = ntc_thermistor_parse_dt(np);
	if (!pdata)
		pdata = pdev->dev.platform_data;

The check for np == NULL could then also be in ntc_thermistor_parse_dt and only
be executed if CONFIG_OF is defined. This would make the code flow look much nicer. 

> +
>  	if (!pdata) {
>  		dev_err(&pdev->dev, "No platform init data supplied.\n");
>  		return -ENODEV;
> @@ -353,9 +420,9 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
>  	data->dev = &pdev->dev;
>  	data->pdev = pdev;
>  	data->pdata = pdata;
> -	strlcpy(data->name, pdev->id_entry->name, sizeof(data->name));
> +	strncpy(data->name, dev_name(&pdev->dev), PLATFORM_NAME_SIZE);
>  
strlcpy is used to ensure 0 termination.
sizeof(data->name) is used to ensure object size.

You should introduce a variable such as pdev_id and either assign pdev->id_entry
or the result of the of function call to it. Other code does that for example
with
	const struct of_device_id *of_id =
	                        of_match_device(of_match_ptr(coda_dt_ids),
				&pdev->dev);
	const struct platform_device_id *pdev_id;
	...
	pdev_id = of_id ? of_id->data : platform_get_device_id(pdev);

and then just use pdev_id. Then you can use
	strncpy(data->name, pdev_id->name, sizeof(data->name));

That requires to change .data in the of_device_id table to point to the
platform_device_id.

> -	switch (pdev->id_entry->driver_data) {
> +	switch (thermistor_get_type(pdev)) {

And then:
	switch (pdev_id) {

>  	case TYPE_NCPXXWB473:
>  		data->comp = ncpXXwb473;
>  		data->n_comp = ARRAY_SIZE(ncpXXwb473);
> @@ -365,9 +432,8 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
>  		data->n_comp = ARRAY_SIZE(ncpXXwl333);
>  		break;
>  	default:
> -		dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
> -				pdev->id_entry->driver_data,
> -				pdev->id_entry->name);
> +		dev_err(&pdev->dev, "Unknown device type: %u\n",
> +				thermistor_get_type(pdev));

		dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
			pdev_id->driver_data,
			pdev_id->name);

>  		return -EINVAL;
>  	}
>  
> @@ -386,9 +452,8 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
>  		goto err_after_sysfs;
>  	}
>  
> -	dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n",
> -			pdev->name, pdev->id, pdev->id_entry->name,
> -			pdev->id_entry->driver_data);
> +	dev_info(&pdev->dev, "Thermistor successfully probed.\n");

Same here again.
	dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n",
		 pdev->name, pdev->id, pdev_id->name,
		 pdev_id->driver_data);

Though I would change that to
	dev_info(&pdev->dev, "Thermistor type %s successfully probed.\n",
		 pdev_id->name);

since the rest of the output is either redundant (name/id) or internal
(pdev_id->driver_data).

> +
>  	return 0;
>  err_after_sysfs:
>  	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
> @@ -406,19 +471,11 @@ static int ntc_thermistor_remove(struct platform_device *pdev)
>  	return 0;
>  }
>  
> -static const struct platform_device_id ntc_thermistor_id[] = {
> -	{ "ncp15wb473", TYPE_NCPXXWB473 },
> -	{ "ncp18wb473", TYPE_NCPXXWB473 },
> -	{ "ncp21wb473", TYPE_NCPXXWB473 },
> -	{ "ncp03wb473", TYPE_NCPXXWB473 },
> -	{ "ncp15wl333", TYPE_NCPXXWL333 },
> -	{ },
> -};
> -
>  static struct platform_driver ntc_thermistor_driver = {
>  	.driver = {
>  		.name = "ntc-thermistor",
>  		.owner = THIS_MODULE,
> +		.of_match_table = of_match_ptr(ntc_match),
>  	},
>  	.probe = ntc_thermistor_probe,
>  	.remove = ntc_thermistor_remove,
> -- 
> 1.7.9.5
> 
> 

Re: [PATCH 2/2] hwmon: NTC: add IIO get channel and read support

[Guenter Roeck]

On Mon, Mar 11, 2013 at 07:39:47AM +0530, Naveen Krishna Chatradhi wrote:
> This patch adds the support to work as a iio device.
> iio_get_channel and iio_raw_read works.
> 
> During the probe ntc driver gets the respective channels of ADC
> and uses iio_raw_read calls to get the ADC converted value.
> 
> Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
> ---
> 
> Still not sure about the read_uV function parameter change and placement.
> 
Me not either. Is the parameter change really necessary ? There was a good
reason to pass pdev, as it lets the called function deal with the device, eg for
error messages.

> There were a few CamelCase warnings during checkpatch run.
> I can clean them if anyone insists.
> 
I actually have a patch sitting somewhere doing just that. Might make sense if I
send it out for review and you rebase your patches on top of it.

>  drivers/hwmon/ntc_thermistor.c               |   36 +++++++++++++++++++++++++-
>  include/linux/platform_data/ntc_thermistor.h |    7 ++++-
>  2 files changed, 41 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
> index cfedbd3..1d31260 100644
> --- a/drivers/hwmon/ntc_thermistor.c
> +++ b/drivers/hwmon/ntc_thermistor.c
> @@ -30,6 +30,11 @@
>  
>  #include <linux/platform_data/ntc_thermistor.h>
>  
> +#include <linux/iio/iio.h>
> +#include <linux/iio/machine.h>
> +#include <linux/iio/driver.h>
> +#include <linux/iio/consumer.h>
> +

One problem with this change is that the driver now mandates the existence of
the IIO subsystem, even if not needed (ie if CONFIG_OF is not defined. We'll
have to limit that impact. I would suggest to keep all the ioo code in the
#ifdef CONFIG_OF block. also, you'll have to add a conditional dependency to
Kconfig.

>  #include <linux/hwmon.h>
>  #include <linux/hwmon-sysfs.h>
>  
> @@ -162,6 +167,28 @@ struct ntc_data {
>  	char name[PLATFORM_NAME_SIZE];
>  };
>  
> +static int ntc_adc_read(struct ntc_thermistor_platform_data *pdata)
> +{

Better name it ntc_adc_iio_read.

> +	struct iio_channel *channel = pdata->chan;
> +	unsigned int result;
> +	int val, ret;
> +
> +	if (!channel)
> +		return -EINVAL;
> +
You should check this earlier (see below).

> +	ret = iio_read_channel_raw(channel, &val);
> +	if (ret < 0) {
> +		pr_err("read channel() error: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/* unit: mV */
> +	result = pdata->pullup_uV * (s64) val;
> +	result >>= 12;
> +
> +	return result;
> +}
> +
>  #ifdef CONFIG_OF
>  static void ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata,
>  							struct device_node *np)
> @@ -173,6 +200,8 @@ static void ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata,
>  		pdata->connect = NTC_CONNECTED_POSITIVE;
>  	else /* status change should be possible if not always on. */
>  		pdata->connect = NTC_CONNECTED_GROUND;
> +
> +	pdata->read_uV = ntc_adc_read;
>  }
>  #else
>  static void
> @@ -317,7 +346,7 @@ static int ntc_thermistor_get_ohm(struct ntc_data *data)
>  		return data->pdata->read_ohm(data->pdev);
>  
>  	if (data->pdata->read_uV) {
> -		read_uV = data->pdata->read_uV(data->pdev);
> +		read_uV = data->pdata->read_uV(data->pdata);

I am really not happy with this parameter change.
you should be able to get the pointer to pdata with
		data = platform_get_drvdata(pdev);
		pdata = data->pdata;

>  		if (read_uV < 0)
>  			return read_uV;
>  		return get_ohm_of_thermistor(data, read_uV);
> @@ -417,6 +446,8 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
>  	if (!data)
>  		return -ENOMEM;
>  
> +	pdata->chan = iio_channel_get(&pdev->dev, NULL);
> +
I think this should be assigned together with read_uV in ntc_thermistor_parse_dt,
and bail out if it returns an error. It does not make sense to instantiate
the driver otherwise if OF is used to construct pdata.

Also, iio_channel_get can return an error, so you have to check the returned
value for an error return with IS_ERR. This error can be EDEFER, so make
sure it is returned to the caller to cause the probe t be called again later.

>  	data->dev = &pdev->dev;
>  	data->pdev = pdev;
>  	data->pdata = pdata;
> @@ -457,15 +488,18 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
>  	return 0;
>  err_after_sysfs:
>  	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
> +	iio_channel_release(pdata->chan);

That will crash nicely if pdata->chan is not set or has an error.

>  	return ret;
>  }
>  
>  static int ntc_thermistor_remove(struct platform_device *pdev)
>  {
>  	struct ntc_data *data = platform_get_drvdata(pdev);
> +	struct ntc_thermistor_platform_data *pdata = data->pdata;
>  
>  	hwmon_device_unregister(data->hwmon_dev);
>  	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
> +	iio_channel_release(pdata->chan);

Same here - you'll have to make sure pdata->chan is valid.

>  	platform_set_drvdata(pdev, NULL);
>  
>  	return 0;
> diff --git a/include/linux/platform_data/ntc_thermistor.h b/include/linux/platform_data/ntc_thermistor.h
> index 18f3c3a..671d056 100644
> --- a/include/linux/platform_data/ntc_thermistor.h
> +++ b/include/linux/platform_data/ntc_thermistor.h
> @@ -34,19 +34,24 @@ struct ntc_thermistor_platform_data {
>  	 *
>  	 * pullup_uV, pullup_ohm, pulldown_ohm, and connect are required to use
>  	 * read_uV()
> +	 * takes the platform data structure as the parameter

Please undo this change.

>  	 *
>  	 * How to setup pullup_ohm, pulldown_ohm, and connect is
>  	 * described at Documentation/hwmon/ntc_thermistor
>  	 *
>  	 * pullup/down_ohm: 0 for infinite / not-connected
> +	 *
> +	 * iio_channel to communicate with the ADC which the
> +	 * thermistor is using for conversion of the analog values.
>  	 */
> -	int (*read_uV)(struct platform_device *);
> +	int (*read_uV)(struct ntc_thermistor_platform_data *);

Please undo this change.

>  	int (*read_ohm)(struct platform_device *);
>  	unsigned int pullup_uV;
>  
>  	unsigned int pullup_ohm;
>  	unsigned int pulldown_ohm;
>  	enum { NTC_CONNECTED_POSITIVE, NTC_CONNECTED_GROUND } connect;
> +	struct iio_channel *chan;
>  };
>  
>  #endif /* _LINUX_NTC_H */
> -- 
> 1.7.9.5
> 
> 

Re: [lm-sensors] [PATCH 1/2] hwmon: ntc: Add DT support to NTC thermistor driver

[Guenter Roeck]

On Mon, Mar 11, 2013 at 05:21:44AM -0700, Guenter Roeck wrote:
> On Mon, Mar 11, 2013 at 07:39:46AM +0530, Naveen Krishna Chatradhi wrote:
> > This patch adds the DT support to NTC driver to parse the
> > platform data.
> > 
> > Signed-off-by: Naveen Krishna Chatradhi <ch.naveen-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
> > ---
> >  drivers/hwmon/ntc_thermistor.c |   93 ++++++++++++++++++++++++++++++++--------
> >  1 file changed, 75 insertions(+), 18 deletions(-)
> > 
> > diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
> > index d92b237..cfedbd3 100644
> > --- a/drivers/hwmon/ntc_thermistor.c
> > +++ b/drivers/hwmon/ntc_thermistor.c
> > @@ -26,6 +26,7 @@
> >  #include <linux/math64.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/err.h>
> > +#include <linux/of.h>
> >  
> >  #include <linux/platform_data/ntc_thermistor.h>
> >  
> > @@ -37,6 +38,41 @@ struct ntc_compensation {
> >  	unsigned int	ohm;
> >  };
> >  
> > +static const struct platform_device_id ntc_thermistor_id[] = {
> > +	{ "ncp15wb473", TYPE_NCPXXWB473 },
> > +	{ "ncp18wb473", TYPE_NCPXXWB473 },
> > +	{ "ncp21wb473", TYPE_NCPXXWB473 },
> > +	{ "ncp03wb473", TYPE_NCPXXWB473 },
> > +	{ "ncp15wl333", TYPE_NCPXXWL333 },
> > +	{ },
> > +};
> > +
> > +#ifdef CONFIG_OF
> > +static const struct of_device_id ntc_match[] = {
> > +	{ .compatible = "ntc,ncp15wb473", .data = (void *)TYPE_NCPXXWB473 },
> > +	{ .compatible = "ntc,ncp18wb473", .data = (void *)TYPE_NCPXXWB473 },
> > +	{ .compatible = "ntc,ncp21wb473", .data = (void *)TYPE_NCPXXWB473 },
> > +	{ .compatible = "ntc,ncp03wb473", .data = (void *)TYPE_NCPXXWB473 },
> > +	{ .compatible = "ntc,ncp15wl333", .data = (void *)TYPE_NCPXXWL333 },
> 
> Better point to ntc_thermistor_id[TYPE_xxx]. See below.
> 
> > +	{ },
> > +};
> > +MODULE_DEVICE_TABLE(of, ntc_match);
> > +#endif
> > +
> > +/* Get NTC type either from device tree or platform data. */
> > +static enum ntc_thermistor_type thermistor_get_type
> > +				(struct platform_device *pdev)
> > +{
> > +	if (pdev->dev.of_node) {
> > +		const struct of_device_id *match;
> > +		match = of_match_node(of_match_ptr(ntc_match),
> > +						pdev->dev.of_node);
> > +		return (unsigned int)match->data;
> > +	}
> > +
> > +	return platform_get_device_id(pdev)->driver_data;
> > +}
> > +
> >  /*
> >   * A compensation table should be sorted by the values of .ohm
> >   * in descending order.
> > @@ -126,6 +162,27 @@ struct ntc_data {
> >  	char name[PLATFORM_NAME_SIZE];
> >  };
> >  
> > +#ifdef CONFIG_OF
> 
> Please merge the two CONFIG_OF blocks into one.
> 
> > +static void ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata,
> > +							struct device_node *np)
> > +{
> > +	of_property_read_u32(np, "pullup-uV", &pdata->pullup_uV);
> > +	of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm);
> > +	of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm);
> > +	if (of_find_property(np, "connected-positive", NULL))
> > +		pdata->connect = NTC_CONNECTED_POSITIVE;
> > +	else /* status change should be possible if not always on. */
> > +		pdata->connect = NTC_CONNECTED_GROUND;
> > +}

Forgot to mention: You'll have to add a devicetree bindings file describing the
bindings.

> > +#else
> > +static void
> > +static void ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata,
> > +							struct device_node *np)
> > +{
> > +	return;
> 
> Unnecessary return statement.
> 
> > +}
> > +#endif
> > +
> >  static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
> >  {
> >  	if (divisor == 0 && dividend == 0)
> > @@ -313,9 +370,19 @@ static const struct attribute_group ntc_attr_group = {
> >  static int ntc_thermistor_probe(struct platform_device *pdev)
> >  {
> >  	struct ntc_data *data;
> > -	struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data;
> > +	struct device_node *np = pdev->dev.of_node;
> > +	struct ntc_thermistor_platform_data *pdata = NULL;
> 
> Unnecessary change. It doesn't hurt if pdata is initialized to non-NULL, and
> initializing it to NULL is unnecessary anyway since it is always assigned below.
> 
> >  	int ret = 0;
> >  
> > +	if (np) {
> > +		pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
> > +		if (!pdata)
> > +			return -ENOMEM;
> > +
> > +		ntc_thermistor_parse_dt(pdata, np);
> 
> This compiles, but the resulting code would not work as the necessary fields
> in pdata are not all filled out. So I think it would be better to merge the code
> with the next patch, as both don't really work independently.
> 
> > +	} else
> > +		pdata = pdev->dev.platform_data;
> 
> Not necessary if you keep above pre-initialization.
> 
> A better idea would be to move the devm_kzalloc into ntc_thermistor_parse_dt
> and return a pointer to pdata from it. Then you would have
> 
> 	pdata = ntc_thermistor_parse_dt(np);
> 	if (!pdata)
> 		pdata = pdev->dev.platform_data;
> 
> The check for np == NULL could then also be in ntc_thermistor_parse_dt and only
> be executed if CONFIG_OF is defined. This would make the code flow look much nicer. 
> 
> > +
> >  	if (!pdata) {
> >  		dev_err(&pdev->dev, "No platform init data supplied.\n");
> >  		return -ENODEV;
> > @@ -353,9 +420,9 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
> >  	data->dev = &pdev->dev;
> >  	data->pdev = pdev;
> >  	data->pdata = pdata;
> > -	strlcpy(data->name, pdev->id_entry->name, sizeof(data->name));
> > +	strncpy(data->name, dev_name(&pdev->dev), PLATFORM_NAME_SIZE);
> >  
> strlcpy is used to ensure 0 termination.
> sizeof(data->name) is used to ensure object size.
> 
> You should introduce a variable such as pdev_id and either assign pdev->id_entry
> or the result of the of function call to it. Other code does that for example
> with
> 	const struct of_device_id *of_id =
> 	                        of_match_device(of_match_ptr(coda_dt_ids),
> 				&pdev->dev);
> 	const struct platform_device_id *pdev_id;
> 	...
> 	pdev_id = of_id ? of_id->data : platform_get_device_id(pdev);
> 
> and then just use pdev_id. Then you can use
> 	strncpy(data->name, pdev_id->name, sizeof(data->name));
> 
> That requires to change .data in the of_device_id table to point to the
> platform_device_id.
> 
> > -	switch (pdev->id_entry->driver_data) {
> > +	switch (thermistor_get_type(pdev)) {
> 
> And then:
> 	switch (pdev_id) {
> 
> >  	case TYPE_NCPXXWB473:
> >  		data->comp = ncpXXwb473;
> >  		data->n_comp = ARRAY_SIZE(ncpXXwb473);
> > @@ -365,9 +432,8 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
> >  		data->n_comp = ARRAY_SIZE(ncpXXwl333);
> >  		break;
> >  	default:
> > -		dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
> > -				pdev->id_entry->driver_data,
> > -				pdev->id_entry->name);
> > +		dev_err(&pdev->dev, "Unknown device type: %u\n",
> > +				thermistor_get_type(pdev));
> 
> 		dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
> 			pdev_id->driver_data,
> 			pdev_id->name);
> 
> >  		return -EINVAL;
> >  	}
> >  
> > @@ -386,9 +452,8 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
> >  		goto err_after_sysfs;
> >  	}
> >  
> > -	dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n",
> > -			pdev->name, pdev->id, pdev->id_entry->name,
> > -			pdev->id_entry->driver_data);
> > +	dev_info(&pdev->dev, "Thermistor successfully probed.\n");
> 
> Same here again.
> 	dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n",
> 		 pdev->name, pdev->id, pdev_id->name,
> 		 pdev_id->driver_data);
> 
> Though I would change that to
> 	dev_info(&pdev->dev, "Thermistor type %s successfully probed.\n",
> 		 pdev_id->name);
> 
> since the rest of the output is either redundant (name/id) or internal
> (pdev_id->driver_data).
> 
> > +
> >  	return 0;
> >  err_after_sysfs:
> >  	sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
> > @@ -406,19 +471,11 @@ static int ntc_thermistor_remove(struct platform_device *pdev)
> >  	return 0;
> >  }
> >  
> > -static const struct platform_device_id ntc_thermistor_id[] = {
> > -	{ "ncp15wb473", TYPE_NCPXXWB473 },
> > -	{ "ncp18wb473", TYPE_NCPXXWB473 },
> > -	{ "ncp21wb473", TYPE_NCPXXWB473 },
> > -	{ "ncp03wb473", TYPE_NCPXXWB473 },
> > -	{ "ncp15wl333", TYPE_NCPXXWL333 },
> > -	{ },
> > -};
> > -
> >  static struct platform_driver ntc_thermistor_driver = {
> >  	.driver = {
> >  		.name = "ntc-thermistor",
> >  		.owner = THIS_MODULE,
> > +		.of_match_table = of_match_ptr(ntc_match),
> >  	},
> >  	.probe = ntc_thermistor_probe,
> >  	.remove = ntc_thermistor_remove,
> > -- 
> > 1.7.9.5
> > 
> > 
> 
> _______________________________________________
> lm-sensors mailing list
> lm-sensors-GZX6beZjE8VD60Wz+7aTrA@public.gmane.org
> http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
> 

Re: [PATCH 2/2] hwmon: NTC: add IIO get channel and read support

[Doug Anderson]

Naveen,

On Sun, Mar 10, 2013 at 7:09 PM, Naveen Krishna Chatradhi
<ch.naveen@samsung.com> wrote:
> @@ -317,7 +346,7 @@ static int ntc_thermistor_get_ohm(struct ntc_data *data)
>                 return data->pdata->read_ohm(data->pdev);
>
>         if (data->pdata->read_uV) {
> -               read_uV = data->pdata->read_uV(data->pdev);
> +               read_uV = data->pdata->read_uV(data->pdata);

This doesn't apply for me.  Did you perhaps accidentally send up a
patch against the version of the driver that's in the Chrome OS tree?
You should be sending patches against some tree that's upstream
(linux, linux-next, iio, ...).

Thanks!

-Doug