From: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
To: linux-kernel@vger.kernel.org, lm-sensors@lm-sensors.org
Cc: devicetree-discuss@lists.ozlabs.org, khali@linux-fr.org,
        linux@roeck-us.net, dianders@chromium.org, naveenkrishna.ch@gmail.com
Subject: [PATCH v2] hwmon: ntc: Add DT with IIO support to NTC thermistor driver
Date: Tue, 12 Mar 2013 14:09:26 +0530
Message-id: <1363077566-6254-1-git-send-email-ch.naveen@samsung.com>
DLP-Filter: Pass
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 9665
Lines: 313

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

Also adds the support to work as an iio device.

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>
---
Changes since v1:
1. Combimed all the IIO and OF/device tree changes under CONFIG_OF
2. parse_dt function now checks for of_node and iio_channels sanity
3. merged both the patches to single, as they cant build independently
4. used pdev_id for proper logging and support of DT and non DT based probing
5. Rebased on linux git tree
6. Added documentation for device tree bindings

Sorry, for posting a patch rebased on local working branch.
Thanks Doug, for pointing out.
 .../devicetree/bindings/hwmon/ntc_thermistor.txt   |   29 +++++
 drivers/hwmon/ntc_thermistor.c                     |  133 +++++++++++++++++---
 include/linux/platform_data/ntc_thermistor.h       |    6 +-
 3 files changed, 148 insertions(+), 20 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt

diff --git a/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt b/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
new file mode 100644
index 0000000..731a78f
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/ntc_thermistor.txt
@@ -0,0 +1,29 @@
+NTC Thermistor hwmon sensors
+-------------------------------
+
+Requires node properties:
+- "compatible" value : one of
+	"ntc,ncp15wb473"
+	"ntc,ncp18wb473"
+	"ntc,ncp21wb473"
+	"ntc,ncp03wb473"
+	"ntc,ncp15wl333"
+- "pullup-uV"	Pull up voltage in micro volts
+- "pullup-ohm"	Pull up resistor value in ohms
+- "pulldown-ohm" Pull down resistor value in ohms
+- "connected-positive" Always ON, If not specified.
+		Status change is possible, value (1) is assigned.
+- "io-channels"	Channel node of ADC to be used for
+		conversion.
+
+Read more about iio bindings at
+	Documentation/devicetree/bindings/iio/iio-bindings.txt
+	
+Example:
+	ncp15wb473@0 {
+		compatible = "ntc,ncp15wb473";
+		pullup-uV = <1800000>;
+		pullup-ohm = <47000>;
+		pulldown-ohm = <0>;
+		io-channels = <&adc 3>;
+	};
diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c
index b5f63f9..81d5bdc 100644
--- a/drivers/hwmon/ntc_thermistor.c
+++ b/drivers/hwmon/ntc_thermistor.c
@@ -26,9 +26,16 @@
 #include <linux/math64.h>
 #include <linux/platform_device.h>
 #include <linux/err.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
 
 #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>
 
@@ -37,6 +44,15 @@ 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 },
+	{ },
+};
+
 /*
  * A compensation table should be sorted by the values of .ohm
  * in descending order.
@@ -125,6 +141,76 @@ struct ntc_data {
 	char name[PLATFORM_NAME_SIZE];
 };
 
+#ifdef CONFIG_OF
+static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata)
+{
+	struct iio_channel *channel = pdata->chan;
+	unsigned int result;
+	int val, ret;
+
+	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;
+}
+
+static const struct of_device_id ntc_match[] = {
+	{ .compatible = "ntc,ncp15wb473",
+		.data = &ntc_thermistor_id[TYPE_NCPXXWB473] },
+	{ .compatible = "ntc,ncp18wb473",
+		.data = &ntc_thermistor_id[TYPE_NCPXXWB473] },
+	{ .compatible = "ntc,ncp21wb473",
+		.data = &ntc_thermistor_id[TYPE_NCPXXWB473] },
+	{ .compatible = "ntc,ncp03wb473",
+		.data = &ntc_thermistor_id[TYPE_NCPXXWB473] },
+	{ .compatible = "ntc,ncp15wl333",
+		.data = &ntc_thermistor_id[TYPE_NCPXXWL333] },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ntc_match);
+
+static int ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata,
+						struct platform_device *pdev)
+{
+	struct iio_channel *chan;
+	struct device_node *np = pdev->dev.of_node;
+
+	if (!np)
+		return -ENODEV;
+
+	chan = iio_channel_get(&pdev->dev, NULL);
+	if (IS_ERR(chan))
+		return IS_ERR(chan);
+
+	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;
+
+	pdata->chan = chan;
+	pdata->read_uV = ntc_adc_iio_read;
+
+	return 0;
+}
+#else
+static int ntc_thermistor_parse_dt(struct ntc_thermistor_platform_data *pdata,
+						struct platform_device *pdev)
+{
+	return -ENODEV;
+}
+#endif
+
 static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
 {
 	if (divisor == 0 && dividend == 0)
@@ -259,7 +345,7 @@ static int ntc_thermistor_get_ohm(struct ntc_data *data)
 		return data->pdata->read_ohm();
 
 	if (data->pdata->read_uV) {
-		read_uV = data->pdata->read_uV();
+		read_uV = data->pdata->read_uV(data->pdata);
 		if (read_uV < 0)
 			return read_uV;
 		return get_ohm_of_thermistor(data, read_uV);
@@ -311,9 +397,22 @@ static const struct attribute_group ntc_attr_group = {
 
 static int ntc_thermistor_probe(struct platform_device *pdev)
 {
+	const struct of_device_id *of_id =
+			of_match_device(of_match_ptr(ntc_match), &pdev->dev);
+	const struct platform_device_id *pdev_id;
+	struct ntc_thermistor_platform_data *pdata;
 	struct ntc_data *data;
-	struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data;
-	int ret = 0;
+	int ret;
+
+	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return -ENOMEM;
+
+	ret = ntc_thermistor_parse_dt(pdata, pdev);
+	if (ret == -EPROBE_DEFER)
+		return ret;
+	else if (ret < 0)
+		pdata = pdev->dev.platform_data;
 
 	if (!pdata) {
 		dev_err(&pdev->dev, "No platform init data supplied.\n");
@@ -349,11 +448,13 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
 	if (!data)
 		return -ENOMEM;
 
+	pdev_id = of_id ? of_id->data : platform_get_device_id(pdev);
+
 	data->dev = &pdev->dev;
 	data->pdata = pdata;
-	strlcpy(data->name, pdev->id_entry->name, sizeof(data->name));
+	strncpy(data->name, pdev_id->name, sizeof(data->name));
 
-	switch (pdev->id_entry->driver_data) {
+	switch (pdev_id->driver_data) {
 	case TYPE_NCPXXWB473:
 		data->comp = ncpXXwb473;
 		data->n_comp = ARRAY_SIZE(ncpXXwb473);
@@ -364,8 +465,7 @@ static int ntc_thermistor_probe(struct platform_device *pdev)
 		break;
 	default:
 		dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
-				pdev->id_entry->driver_data,
-				pdev->id_entry->name);
+				pdev_id->driver_data, pdev_id->name);
 		return -EINVAL;
 	}
 
@@ -384,39 +484,34 @@ 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 type: %s successfully probed.\n",
+								pdev->name);
+
 	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;
 }
 
-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,
diff --git a/include/linux/platform_data/ntc_thermistor.h b/include/linux/platform_data/ntc_thermistor.h
index 88734e8..6cf5081 100644
--- a/include/linux/platform_data/ntc_thermistor.h
+++ b/include/linux/platform_data/ntc_thermistor.h
@@ -39,13 +39,17 @@ struct ntc_thermistor_platform_data {
 	 * described at Documentation/hwmon/ntc_thermistor
 	 *
 	 * pullup/down_ohm: 0 for infinite / not-connected
+	 *
+	 * chan: iio_channel pointer to communicate with the ADC which the
+	 * thermistor is using for conversion of the analog values.
 	 */
-	int (*read_uV)(void);
+	int (*read_uV)(struct ntc_thermistor_platform_data *);
 	unsigned int pullup_uV;
 
 	unsigned int pullup_ohm;
 	unsigned int pulldown_ohm;
 	enum { NTC_CONNECTED_POSITIVE, NTC_CONNECTED_GROUND } connect;
+	struct iio_channel *chan;
 
 	int (*read_ohm)(void);
 };
-- 
1.7.9.5

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