iio: dac: support the ad8460 Waveform DAC

The AD8460 is a “bits in, power out” high voltage, high-power,
high-speed driver optimized for large output current (up to ±1 A)
and high slew rate (up to ±1800 V/μs) at high voltage (up to ±40 V)
into capacitive loads.

A digital engine implements user-configurable features: modes for
digital input, programmable supply current, and fault monitoring
and programmable protection settings for output current,
output voltage, and junction temperature. The AD8460 operates on
high voltage dual supplies up to ±55 V and a single low voltage
supply of 5 V.

Backported few API's not yet compatible with ADI linux fork

devm_iio_dmaengine_buffer_setup_ext
- Reverted to "devm_iio_dmaengine_buffer_setup"
devm_mutex_init
- Reverted to "mutex_init"
in_range
- Used explicit range checking

Signed-off-by: Mariel Tinaco <Mariel.Tinaco@analog.com>
Link: https://patch.msgid.link/20240912095435.18639-3-Mariel.Tinaco@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: MarielTinaco

MAINTAINERS

@@ -1347,6 +1347,7 @@ L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/dac/adi,ad8460.yaml
+F:	drivers/iio/dac/ad8460.c
 
 ANALOG DEVICES INC AD9389B DRIVER
 M:	Hans Verkuil <hverkuil-cisco@xs4all.nl>

drivers/iio/dac/Kconfig

@@ -276,6 +276,19 @@ config AD7303
 	  To compile this driver as module choose M here: the module will be called
 	  ad7303.
 
+config AD8460
+	tristate "Analog Devices AD8460 DAC driver"
+	depends on SPI
+	select REGMAP_SPI
+	select IIO_BUFFER
+	select IIO_BUFFER_DMAENGINE
+	help
+	  Say yes here to build support for Analog Devices AD8460 Digital to
+	  Analog Converters (DAC).
+
+	  To compile this driver as a module choose M here: the module will be called
+	  ad8460.
+
 config AD8801
 	tristate "Analog Devices AD8801/AD8803 DAC driver"
 	depends on SPI_MASTER

drivers/iio/dac/Makefile

@@ -29,6 +29,7 @@ obj-$(CONFIG_AD5686_SPI) += ad5686-spi.o
 obj-$(CONFIG_AD5696_I2C) += ad5696-i2c.o
 obj-$(CONFIG_AD7293) += ad7293.o
 obj-$(CONFIG_AD7303) += ad7303.o
+obj-$(CONFIG_AD8460) += ad8460.o
 obj-$(CONFIG_AD8801) += ad8801.o
 obj-$(CONFIG_CIO_DAC) += cio-dac.o
 obj-$(CONFIG_DPOT_DAC) += dpot-dac.o