[PATCH 2/2] hwmon: (chipcap2) Add support for label

[Flaviu Nistor <flaviu.nistor@gmail.com>]

Add support for label sysfs attribute similar to other hwmon devices.
This is particularly useful for systems with multiple sensors on the
same board, where identifying individual sensors is much easier since
labels can be defined via device tree.

Signed-off-by: Flaviu Nistor <flaviu.nistor@gmail.com>
---
 Documentation/hwmon/chipcap2.rst |  2 ++
 drivers/hwmon/chipcap2.c         | 25 +++++++++++++++++++++++--
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/Documentation/hwmon/chipcap2.rst b/Documentation/hwmon/chipcap2.rst
index dc165becc64c..c38d87b91b69 100644
--- a/Documentation/hwmon/chipcap2.rst
+++ b/Documentation/hwmon/chipcap2.rst
@@ -70,4 +70,6 @@ humidity1_min_hyst:             RW      humidity low hystersis
 humidity1_max_hyst:             RW      humidity high hystersis
 humidity1_min_alarm:            RO      humidity low alarm indicator
 humidity1_max_alarm:            RO      humidity high alarm indicator
+humidity1_label:                RO      descriptive name for the sensor
+temp1_label:                    RO      descriptive name for the sensor
 =============================== ======= ========================================
diff --git a/drivers/hwmon/chipcap2.c b/drivers/hwmon/chipcap2.c
index 4aecf463180f..086571d556b7 100644
--- a/drivers/hwmon/chipcap2.c
+++ b/drivers/hwmon/chipcap2.c
@@ -22,6 +22,8 @@
 #include <linux/irq.h>
 #include <linux/module.h>
 #include <linux/regulator/consumer.h>
+#include <linux/mod_devicetable.h>
+#include <linux/property.h>
 
 #define CC2_START_CM			0xA0
 #define CC2_START_NOM			0x80
@@ -83,6 +85,7 @@ struct cc2_data {
 	struct i2c_client *client;
 	struct regulator *regulator;
 	const char *name;
+	const char *label;
 	int irq_ready;
 	int irq_low;
 	int irq_high;
@@ -449,6 +452,8 @@ static umode_t cc2_is_visible(const void *data, enum hwmon_sensor_types type,
 		switch (attr) {
 		case hwmon_humidity_input:
 			return 0444;
+		case hwmon_humidity_label:
+			return cc2->label ? 0444 : 0;
 		case hwmon_humidity_min_alarm:
 			return cc2->rh_alarm.low_alarm_visible ? 0444 : 0;
 		case hwmon_humidity_max_alarm:
@@ -466,6 +471,8 @@ static umode_t cc2_is_visible(const void *data, enum hwmon_sensor_types type,
 		switch (attr) {
 		case hwmon_temp_input:
 			return 0444;
+		case hwmon_temp_label:
+			return cc2->label ? 0444 : 0;
 		default:
 			return 0;
 		}
@@ -552,6 +559,16 @@ static int cc2_humidity_max_alarm_status(struct cc2_data *data, long *val)
 	return 0;
 }
 
+static int cc2_read_string(struct device *dev, enum hwmon_sensor_types type,
+			   u32 attr, int channel, const char **str)
+{
+	struct cc2_data *data = dev_get_drvdata(dev);
+
+	*str = data->label;
+
+	return 0;
+}
+
 static int cc2_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
 		    int channel, long *val)
 {
@@ -670,8 +687,9 @@ static int cc2_request_alarm_irqs(struct cc2_data *data, struct device *dev)
 }
 
 static const struct hwmon_channel_info *cc2_info[] = {
-	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
-	HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT | HWMON_H_MIN | HWMON_H_MAX |
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_LABEL),
+	HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT | HWMON_H_LABEL |
+			   HWMON_H_MIN | HWMON_H_MAX |
 			   HWMON_H_MIN_HYST | HWMON_H_MAX_HYST |
 			   HWMON_H_MIN_ALARM | HWMON_H_MAX_ALARM),
 	NULL
@@ -680,6 +698,7 @@ static const struct hwmon_channel_info *cc2_info[] = {
 static const struct hwmon_ops cc2_hwmon_ops = {
 	.is_visible = cc2_is_visible,
 	.read = cc2_read,
+	.read_string = cc2_read_string,
 	.write = cc2_write,
 };
 
@@ -710,6 +729,8 @@ static int cc2_probe(struct i2c_client *client)
 		return dev_err_probe(dev, PTR_ERR(data->regulator),
 				     "Failed to get regulator\n");
 
+	device_property_read_string(dev, "label", &data->label);
+
 	ret = cc2_request_ready_irq(data, dev);
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to request ready irq\n");
-- 
2.34.1