• AD5300
• AD5301
• AD5310
• AD5311
• AD5320
• AD5321
• AD5444
• AD5446
• AD5450
• AD5451
• AD5452
• AD5453
• AD5512A
• AD5541A
• AD5542
• AD5542A
• AD5543
• AD5553
• AD5600
• AD5601
• AD5602
• AD5611
• AD5612
• AD5620
• AD5620-1
• AD5620-2
• AD5620-3
• AD5621
• AD5622
• AD5640
• AD5640-1
• AD5640-2
• AD5640-3
• AD5641
• AD5660
• AD5660-1
• AD5660-2
• AD5660-3
• AD5662

• CN0009
• CN0143
• CN0151
• CN0156
• CN0169
• CN0179
• CN0181
• CN0202
• CN0203
• CN0204
• CN0348

• EVAL-AD5446SDZ
• EVAL-AD5453SDZ
• EVAL-AD5541ASDZ
• EVAL-AD5542ASDZ
• EVAL-AD5543SDZ
• EVAL-AD5600PMDZ
• EVAL-AD5621EBZ
• EVAL-AD5620EBZ
• EVAL-AD5660EBZ
• EVAL-AD5662EBZ

This is a Linux industrial I/O (IIO) subsystem driver, targeting single channel serial interface DACs. The industrial I/O subsystem provides a unified framework for drivers for many different types of converters and sensors using a number of different physical interfaces (i2c, spi, etc). See IIO for more information.

Below example specifies a 2.5 Volt reference for the SPI device 3 on SPI-Bus 0. (spi0.3)

#if defined(CONFIG_REGULATOR_FIXED_VOLTAGE) || defined(CONFIG_REGULATOR_FIXED_VOLTAGE_MODULE)
static struct regulator_consumer_supply ad5446_consumer_supplies[] = {
	REGULATOR_SUPPLY("vcc", "spi0.3"),
};
?
static struct regulator_init_data stamp_avdd_reg_init_data = {
	.constraints	= {
		.name	= "2V5",
		.valid_ops_mask = REGULATOR_CHANGE_STATUS,
	},
	.consumer_supplies = ad5446_consumer_supplies,
	.num_consumer_supplies = ARRAY_SIZE(ad5446_consumer_supplies),
};
?
static struct fixed_voltage_config stamp_vdd_pdata = {
	.supply_name	= "board-2V5",
	.microvolts	= 2500000,
	.gpio		= -EINVAL,
	.enabled_at_boot = 0,
	.init_data	= &stamp_avdd_reg_init_data,
};
static struct platform_device brd_voltage_regulator = {
	.name		= "reg-fixed-voltage",
	.id		= -1,
	.num_resources	= 0,
	.dev		= {
		.platform_data	= &stamp_vdd_pdata,
	},
};
#endif

static struct platform_device *board_devices[] __initdata = {
#if defined(CONFIG_REGULATOR_FIXED_VOLTAGE) || defined(CONFIG_REGULATOR_FIXED_VOLTAGE_MODULE)
	&brd_voltage_regulator
#endif
};

static int __init board_init(void)
{
	[--snip--]
?
	platform_add_devices(board_devices, ARRAY_SIZE(board_devices));
?
	[--snip--]
?
	return 0;
}
arch_initcall(board_init);

Depending on the converter IC used, you may need to set the modalias accordingly, matching your part name.

It may also required to adjust max_speed_hz. Please consult the datasheet, for maximum spi clock supported by the device in question.

static struct spi_board_info board_spi_board_info[] __initdata = {
#if defined(CONFIG_AD5446) || /
 	defined(CONFIG_AD5446_MODULE)
	{
		/* the modalias must be the same as spi device driver name */
		.modalias = "ad5446", /* Name of spi_driver for this device */
		.max_speed_hz = 1000000,     /* max spi clock (SCK) speed in HZ */
		.bus_num = 0, /* Framework bus number */
		.chip_select = 3, /* Framework chip select */
		.mode = SPI_MODE_3,
	},
#endif
};

static int __init board_init(void)
{
	[--snip--]
?
	spi_register_board_info(board_spi_boar
d_info, ARRAY_SIZE(board_spi_board_info));
?
	[--snip--]
?
	return 0;
}
arch_initcall(board_init);

Required devicetree properties:

• compatible: Needs to be “adi,” followed by the name of the device. E.g. “adi,ad5446”
• reg: The chipselect number used for the device
• spi-max-frequency: Maximum SPI clock frequency
• vcc-supply: VCC voltage supply regulator

       dac_vcc: fixedregulator@1 {
              compatible = "regulator-fixed";
              regulator-name = "fixed-supply";
              regulator-min-microvolt = <2500000>;
              regulator-max-microvolt = <2500000>;
              regulator-boot-on;
       };

       axi_spi_1: spi@42040000 {
              #address-cells = <1>;
              #size-cells = <0>;
              compatible = "xlnx,axi-spi-1.02.a", "xlnx,xps-spi-2.00.a";
               ...
              ad5446@0 {
                     compatible = "adi,ad5446";
                     reg = <0>;
                     spi-max-frequency = <1000000>;
                     spi-cpha;
                     spi-cpol;
                     vcc-supply = <&dac_vcc>;
              };
        };

Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)

Linux Kernel Configuration
	Device Drivers  --->
		<*> Industrial I/O support --->
			--- Industrial I/O support
			[--snip--]
			*** Digital to analog convertors ***
				[--snip--]
				<*> Analog Devices AD5446 and similar single channel DACs driver
				[--snip--]

Description:
scale to be applied to out_voltage0_raw in order to obtain the measured voltage in millivolts.

root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> cat out_voltage_scale
0.152

Description:
/sys/bus/iio/devices/iio:deviceX/out_voltageY_raw

Raw (unscaled, no bias etc.) output voltage for channel Y.

root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> echo 1234 > out_voltage0_raw

U = out_voltage0_raw * out_voltage_scale = 1234 * 0.152 mV = 187.568 mV

/sys/bus/iio/devices/iio:deviceX/out_voltage_powerdown_mode_available

Description:
Lists all available output power down modes.

root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> cat out_voltage_powerdown_mode_available
1kohm_to_gnd 100kohm_to_gnd three_state

/sys/bus/iio/devices/iio:deviceX/out_voltage_powerdown_mode

Description:
Specifies the output power down mode. DAC output stage is disconnected from the amplifier and

For a list of available output power down options read outX_powerdown_mode_available.

root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> echo three_state > out_voltage_powerdown_mode
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> cat out_voltage_powerdown_mode
three_state

/sys/bus/iio/devices/iio:deviceX/out_voltageY_powerdown

Description:
Writing 1 causes output Y to enter the power down mode specified by the corresponding out_voltageY_powerdown_mode. Clearing returns to normal operation. Y may be suppressed if all outputs are controlled together.

root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> echo 1 > out_voltage0_powerdown
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> cat out_voltage0_powerdown
1
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> echo 0 > out_voltage0_powerdown
root:/sys/devices/platform/bfin-spi.0/spi0.3/iio:device0> cat out_voltage0_powerdown
0