staging:iio:dac: Add AD5421 driver

This patch adds support for the Analog Devices AD5421 Loop-Powered, 4mA to 20mA
DAC.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/dac/Kconfig

@@ -24,6 +24,16 @@ config AD5360
 	  To compile this driver as module choose M here: the module will be called
 	  ad5360.
 
+config AD5421
+	tristate "Analog Devices AD5421 DAC driver"
+	depends on SPI
+	help
+	  Say yes here to build support for Analog Devices AD5421 loop-powered
+	  digital-to-analog convertors (DAC).
+
+	  To compile this driver as module choose M here: the module will be called
+	  ad5421.
+
 config AD5624R_SPI
 	tristate "Analog Devices AD5624/44/64R DAC spi driver"
 	depends on SPI

drivers/staging/iio/dac/Makefile

@@ -3,6 +3,7 @@
 #
 
 obj-$(CONFIG_AD5360) += ad5360.o
+obj-$(CONFIG_AD5421) += ad5421.o
 obj-$(CONFIG_AD5624R_SPI) += ad5624r_spi.o
 obj-$(CONFIG_AD5064) += ad5064.o
 obj-$(CONFIG_AD5504) += ad5504.o

drivers/staging/iio/dac/ad5421.h

+#ifndef __IIO_DAC_AD5421_H__
+#define __IIO_DAC_AD5421_H__
+
+/*
+ * TODO: This file needs to go into include/linux/iio
+ */
+
+/**
+ * enum ad5421_current_range - Current range the AD5421 is configured for.
+ * @AD5421_CURRENT_RANGE_4mA_20mA: 4 mA to 20 mA (RANGE1,0 pins = 00)
+ * @AD5421_CURRENT_RANGE_3mA8_21mA: 3.8 mA to 21 mA (RANGE1,0 pins = x1)
+ * @AD5421_CURRENT_RANGE_3mA2_24mA: 3.2 mA to 24 mA (RANGE1,0 pins = 10)
+ */
+
+enum ad5421_current_range {
+	AD5421_CURRENT_RANGE_4mA_20mA,
+	AD5421_CURRENT_RANGE_3mA8_21mA,
+	AD5421_CURRENT_RANGE_3mA2_24mA,
+};
+
+/**
+ * struct ad5421_platform_data - AD5421 DAC driver platform data
+ * @external_vref: whether an external reference voltage is used or not
+ * @current_range: Current range the AD5421 is configured for
+ */
+
+struct ad5421_platform_data {
+	bool external_vref;
+	enum ad5421_current_range current_range;
+};
+
+#endif