[PATCH] iio: health: max30100: add config for LED current

[Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Allow the current for both RED and IR LEDs to be set via an device tree
property setting.

This is an optional setting that is useful for applications that have a
known glass attenuation factor.

Signed-off-by: Matt Ranostay <mranostay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 .../devicetree/bindings/iio/health/max30100.txt     |  7 +++++++
 drivers/iio/health/max30100.c                       | 21 +++++++++++++++------
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/health/max30100.txt b/Documentation/devicetree/bindings/iio/health/max30100.txt
index f6fbac6..009314c 100644
--- a/Documentation/devicetree/bindings/iio/health/max30100.txt
+++ b/Documentation/devicetree/bindings/iio/health/max30100.txt
@@ -11,11 +11,18 @@ Required properties:
   Refer to interrupt-controller/interrupts.txt for generic
   interrupt client node bindings.
 
+Optional properties:
+  - max30100,led-current: configuration for LED current (in mA) while the engine
+    is running. Upper nibble is for the RED LED, and lower nibble the IR LED.
+
+    Refer to the datasheet for the current mapping values.
+
 Example:
 
 max30100@057 {
 	compatible = "maxim,max30100";
 	reg = <57>;
+	max30100,led-current = <0x7f>;
 	interrupt-parent = <&gpio1>;
 	interrupts = <16 2>;
 };
diff --git a/drivers/iio/health/max30100.c b/drivers/iio/health/max30100.c
index 9d1c81f..37e8d7e 100644
--- a/drivers/iio/health/max30100.c
+++ b/drivers/iio/health/max30100.c
@@ -13,7 +13,7 @@
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU General Public License for more details.
  *
- * TODO: allow LED current and pulse length controls via device tree properties
+ * TODO: enable pulse length controls via device tree properties
  */
 
 #include <linux/module.h>
@@ -24,6 +24,7 @@
 #include <linux/irq.h>
 #include <linux/i2c.h>
 #include <linux/mutex.h>
+#include <linux/of.h>
 #include <linux/regmap.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/buffer.h>
@@ -245,13 +246,21 @@ static irqreturn_t max30100_interrupt_handler(int irq, void *private)
 
 static int max30100_chip_init(struct max30100_data *data)
 {
+	struct device *dev = &data->client->dev;
+	struct device_node *np = dev->of_node;
 	int ret;
+	u32 val;
 
-	/* RED IR LED = 24mA, IR LED = 50mA */
-	ret = regmap_write(data->regmap, MAX30100_REG_LED_CONFIG,
-				(MAX30100_REG_LED_CONFIG_24MA <<
-				 MAX30100_REG_LED_CONFIG_RED_LED_SHIFT) |
-				 MAX30100_REG_LED_CONFIG_50MA);
+	ret = of_property_read_u32(np, "max30100,led-current", &val);
+	if (ret) {
+		/* Default to 24 mA RED LED, 50 mA IR LED */
+		val = (MAX30100_REG_LED_CONFIG_24MA <<
+			MAX30100_REG_LED_CONFIG_RED_LED_SHIFT) |
+			MAX30100_REG_LED_CONFIG_50MA;
+		dev_warn(dev, "no led-current set, defaulting to %d", val);
+	}
+
+	ret = regmap_write(data->regmap, MAX30100_REG_LED_CONFIG, val & 0xFF);
 	if (ret)
 		return ret;
 
-- 
2.6.4