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--- resources:tools-software:linux-drivers:iio-adc:ad7998 [06 Mar 2015 09:39] – [Files] Michael Hennerich
+++ resources:tools-software:linux-drivers:iio-adc:ad7998 [06 Mar 2015 10:27] – update Michael Hennerich
@@ Line 51: / Line 51: @@
 {{page>software/linux/docs/platform_and_bus_model#Platform Data&noheader&firstseconly&noeditbtn}}
-The reference voltage may vary between boards and models. The platform_data for the device's "struct device" holds this information.
-<source trunk/drivers/staging/iio/adc/ad799x.h:ad799x_platform_data{} c linux-kernel>
+===== Specifying reference voltage via the regulator framework =====
+<WRAP tip>
+In case the AD799x on-chip reference is not used,
+this driver requires specifying the reference voltage, by using the Linux regulator framework.
+</WRAP>
+Below example specifies a 2.5 Volt reference for the I2C device 0-0024 on I2C-Bus 0. (**0-0024**)
 <code c>
-static struct ad799x_platform_data ad7998_pdata = {
+#if defined(CONFIG_REGULATOR_FIXED_VOLTAGE) || defined(CONFIG_REGULATOR_FIXED_VOLTAGE_MODULE)
-	.vref_mv = 2500,
+static struct regulator_consumer_supply ad7998_consumer_supplies[] = {
+	REGULATOR_SUPPLY("vref", "0-0024"),
 };
+static struct regulator_init_data board_avdd_reg_init_data = {
+	.constraints	= {
+		.name	= "2V5",
+		.valid_ops_mask = REGULATOR_CHANGE_STATUS,
+	},
+	.consumer_supplies = ad7998_consumer_supplies,
+	.num_consumer_supplies = ARRAY_SIZE(ad7998_consumer_supplies),
+};
+static struct fixed_voltage_config board_vref_pdata = {
+	.supply_name	= "board-2V5",
+	.microvolts	= 2500000,
+	.gpio		= -EINVAL,
+	.enabled_at_boot = 0,
+	.init_data	= &board_avdd_reg_init_data,
+};
+static struct platform_device brd_voltage_regulator = {
+	.name		= "reg-fixed-voltage",
+	.id		= -1,
+	.num_resources	= 0,
+	.dev		= {
+		.platform_data	= &board_vref_pdata,
+	},
+};
+#endif
 </code>
-<WRAP tip>
+<code c>
-In case platform_data is not present or set to NULL, the driver will use the AD7998 internal reference.
+static struct platform_device *board_devices[] __initdata = {
-</WRAP>
+#if defined(CONFIG_REGULATOR_FIXED_VOLTAGE) || defined(CONFIG_REGULATOR_FIXED_VOLTAGE_MODULE)
+	&brd_voltage_regulator
+#endif
+};
+</code>
+<code c>
+static int __init board_init(void)
+{
+	[--snip--]
+	platform_add_devices(board_devices, ARRAY_SIZE(board_devices));
+	[--snip--]
+	return 0;
+}
+arch_initcall(board_init);
+</code>
 {{page>software/linux/docs/platform_and_bus_model#Declaring I2C devices&firstseconly&noeditbtn}}
@@ Line 93: / Line 144: @@
 }
 arch_initcall(board_init);
+</code>
+===== Devicetree =====
+Required devicetree properties:
+  * compatible: Needs to be "adi," followed by the name of the device. E.g. "adi,ad7798"
+  * reg: The slave address used for the device
+  * vcc-supply: Phandle to the supply regulator
+<code>
+       adc_supply: fixedregulator {
+               compatible = "regulator-fixed";
+               regulator-name = "fixed-supply";
+               regulator-min-microvolt = <3300000>;
+               regulator-max-microvolt = <3300000>;
+       };
+       adc_vref: fixedregulator {
+               compatible = "regulator-fixed";
+               regulator-name = "fixed-supply";
+               regulator-min-microvolt = <2500000>;
+               regulator-max-microvolt = <2500000>;
+       };
+       i2c: i2c@e0007000 {
+               #address-cells = <1>;
+               #size-cells = <0>;
+               compatible = "xlnx,xps-iic-2.00.a";
+               ...
+               ad7798@24 {
+                       compatible = "adi,ad7798";
+                       reg = <0x24>;
+                       vcc-supply = <&adc_supply>;
+                       vref-supply = <&adc_vref>;
+               };
+        };
 </code>

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