linux-kernel - [PATCH v3] hwmon/max6650.c: Add devicetree support

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Date:	Wed, 10 Aug 2016 16:19:47 +0200
From:	Mike Looijmans <mike.looijmans@...ic.nl>
To:	lm-sensors@...sensors.org, devicetree@...r.kernel.org
Cc:	linux@...ck-us.net, linux-kernel@...r.kernel.org,
	Mike Looijmans <mike.looijmans@...ic.nl>
Subject: [PATCH v3] hwmon/max6650.c: Add devicetree support

Parse devicetree parameters for voltage and prescaler setting. This allows
using multiple max6550 devices with varying settings, and also makes it
possible to instantiate and configure the device using devicetree.

Signed-off-by: Mike Looijmans <mike.looijmans@...ic.nl>
---
v3: Resubmit because mailing lists bounced
    Fix style errors as reported by checkpatch.pl
    Fix bug in DT parsing of fan-prescale
v2: Add devicetree binding documentation
    Code changes as suggested by Guenter
    Reduce log info, output only a single line

 .../devicetree/bindings/hwmon/max6650.txt          | 20 ++++++++++++++++
 drivers/hwmon/max6650.c                            | 28 +++++++++++++---------
 2 files changed, 37 insertions(+), 11 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/hwmon/max6650.txt

diff --git a/Documentation/devicetree/bindings/hwmon/max6650.txt b/Documentation/devicetree/bindings/hwmon/max6650.txt
new file mode 100644
index 0000000..89d87c6
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/max6650.txt
@@ -0,0 +1,20 @@
+Bindings for MAX6651 and MAX6650 I2C fan controllers
+
+Required properties:
+- compatible : One of "max6650" or "max6651"
+- reg        : I2C address
+
+Optional properties:
+- fan-voltage    : The supply voltage of the fan. Valid values are 5 and 12.
+                   Default is to use the chip's current setting.
+- fan-prescale   : Pre-scaling value as per datasheet. Valid are 1, 2, 4, 8, 16.
+                   Default is to use the chip's current setting.
+ 
+
+Example:
+	fan-max6650: max6650@1b {
+		reg = <0x1b>;
+		compatible = "max6650";
+		fan-voltage = <12>;
+		fan-prescale = <4>;
+	};
diff --git a/drivers/hwmon/max6650.c b/drivers/hwmon/max6650.c
index 162a520..56a6c87 100644
--- a/drivers/hwmon/max6650.c
+++ b/drivers/hwmon/max6650.c
@@ -41,14 +41,14 @@
 #include <linux/err.h>
 
 /*
- * Insmod parameters
+ * Insmod parameters (for backward compatibility)
  */
 
 /* fan_voltage: 5=5V fan, 12=12V fan, 0=don't change */
 static int fan_voltage;
 /* prescaler: Possible values are 1, 2, 4, 8, 16 or 0 for don't change */
 static int prescaler;
-/* clock: The clock frequency of the chip the driver should assume */
+/* clock: The clock frequency of the chip (max6651 can be clocked externally) */
 static int clock = 254000;
 
 module_param(fan_voltage, int, S_IRUGO);
@@ -566,6 +566,15 @@ static int max6650_init_client(struct max6650_data *data,
 	struct device *dev = &client->dev;
 	int config;
 	int err = -EIO;
+	u32 voltage;
+	u32 prescale;
+
+	if (of_property_read_u32(client->dev.of_node, "fan-voltage",
+				 &voltage))
+		voltage = fan_voltage;
+	if (of_property_read_u32(client->dev.of_node, "fan-prescale",
+				 &prescale))
+		prescale = prescaler;
 
 	config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
 
@@ -574,7 +583,7 @@ static int max6650_init_client(struct max6650_data *data,
 		return err;
 	}
 
-	switch (fan_voltage) {
+	switch (voltage) {
 	case 0:
 		break;
 	case 5:
@@ -584,14 +593,10 @@ static int max6650_init_client(struct max6650_data *data,
 		config |= MAX6650_CFG_V12;
 		break;
 	default:
-		dev_err(dev, "illegal value for fan_voltage (%d)\n",
-			fan_voltage);
+		dev_err(dev, "illegal value for fan_voltage (%d)\n", voltage);
 	}
 
-	dev_info(dev, "Fan voltage is set to %dV.\n",
-		 (config & MAX6650_CFG_V12) ? 12 : 5);
-
-	switch (prescaler) {
+	switch (prescale) {
 	case 0:
 		break;
 	case 1:
@@ -614,10 +619,11 @@ static int max6650_init_client(struct max6650_data *data,
 			 | MAX6650_CFG_PRESCALER_16;
 		break;
 	default:
-		dev_err(dev, "illegal value for prescaler (%d)\n", prescaler);
+		dev_err(dev, "illegal value for prescaler (%d)\n", prescale);
 	}
 
-	dev_info(dev, "Prescaler is set to %d.\n",
+	dev_info(dev, "Fan voltage: %dV, prescaler: %d.\n",
+		 (config & MAX6650_CFG_V12) ? 12 : 5,
 		 1 << (config & MAX6650_CFG_PRESCALER_MASK));
 
 	/*
-- 
1.9.1