dm: adc: add simple ADC uclass implementation

This commit adds:
- new uclass id: UCLASS_ADC
- new uclass driver: drivers/adc/adc-uclass.c

The new uclass's API allows for ADC operation on:
* single-channel with channel selection by a number
* multti-channel with channel selection by bit mask

ADC uclass's functions:
* single-channel:
  - adc_start_channel()        - start channel conversion
  - adc_channel_data()         - get conversion data
  - adc_channel_single_shot()  - start/get conversion data
* multi-channel:
  - adc_start_channels()       - start selected channels conversion
  - adc_channels_data()        - get conversion data
  - adc_channels_single_shot() - start/get conversion data for channels
                                 selected by bit mask
* general:
  - adc_stop()      - stop the conversion
  - adc_vdd_value() - positive reference Voltage value with polarity [uV]
  - adc_vss_value() - negative reference Voltage value with polarity [uV]
  - adc_data_mask() - conversion data bit mask

The device tree can provide below constraints/properties:
- vdd-polarity-negative: if true: Vdd = vdd-microvolts * (-1)
- vss-polarity-negative: if true: Vss = vss-microvolts * (-1)
- vdd-supply:            phandle to Vdd regulator's node
- vss-supply:            phandle to Vss regulator's node
And optional, checked only if the above corresponding, doesn't exist:
  - vdd-microvolts:      positive reference Voltage [uV]
  - vss-microvolts:      negative reference Voltage [uV]

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

doc/device-tree-bindings/adc/adc.txt

@@ -0,0 +1,62 @@
+ADC device binding
+
+There are no mandatory properties for ADC. However, if Voltage info is required,
+then there are two options:
+- use microvolts constraint or
+- use regulator phandle to enable/read supply's Voltage
+
+Properties and constraints:
+*optional and always checked, Voltage polarity info:
+- vdd-polarity-negative:  positive reference Voltage has a negative polarity
+- vss-polarity-negative:  negative reference Voltage has a negative polarity
+
+Chose one option, for each supply (Vdd/Vss):
+
+*optional and always checked, supply Voltage constants:
+- vdd-supply:            phandle to Vdd regulator's node
+- vss-supply:            phandle to Vss regulator's node
+
+*optional and checked only if the above corresponding, doesn't exist:
+- vdd-microvolts:        positive reference Voltage value [uV]
+- vss-microvolts:        negative reference Voltage value [uV]
+
+Example with constant 'Vdd' value:
+adc@1000000 {
+	compatible = "some-adc";
+	reg = <0xaabb000 0x100>;
+	status = "enabled";
+	vdd-microvolts = <1800000>;
+};
+
+Example of supply phandle usage, for the ADC's VDD/VSS references as below:
+   _______         _______
+  |Sandbox|       |Sandbox|
+  : PMIC  :       :  ADC  :
+  .       .       .       .
+  |       | (Vdd) |   AIN0|-->
+  |  BUCK2|-------|VDDref |
+  | (3.3V)|      _|VSSref |
+  |_______|     | |_______|
+               _|_
+
+For the above PMIC, the node can be defined as follows:
+sandbox_pmic {
+	compatible = "sandbox,pmic";
+	...
+	buck2: buck2 {
+		regulator-name = "SUPPLY_3.3V";
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+	};
+	...
+};
+
+For the above ADC, the node can be defined as follows:
+adc@0 {
+	compatible = "sandbox,adc";
+	vdd-supply = <&buck2>;
+	vss-microvolts = <0>;
+};
+
+The ADC uclass code, will enable the supply before start of the conversion,
+but it will not configure the regulator settings.

drivers/Kconfig

@@ -4,6 +4,8 @@ source "drivers/core/Kconfig"
 
 # types of drivers sorted in alphabetical order
 
+source "drivers/adc/Kconfig"
+
 source "drivers/block/Kconfig"
 
 source "drivers/clk/Kconfig"

drivers/Makefile

@@ -35,6 +35,7 @@ obj-$(CONFIG_SPL_SATA_SUPPORT) += block/
 
 else
 
+obj-y += adc/
 obj-$(CONFIG_DM_DEMO) += demo/
 obj-$(CONFIG_BIOSEMU) += bios_emulator/
 obj-y += block/

drivers/adc/Kconfig

@@ -0,0 +1,12 @@
+config ADC
+	bool "Enable ADC drivers using Driver Model"
+	help
+	  This enables ADC API for drivers, which allows driving ADC features
+	  by single and multi-channel methods for:
+	  - start/stop/get data for conversion of a single-channel selected by
+	    a number or multi-channels selected by a bitmask
+	  - get data mask (ADC resolution)
+	  ADC reference Voltage supply options:
+	  - methods for get Vdd/Vss reference Voltage values with polarity
+	  - support supply's phandle with auto-enable
+	  - supply polarity setting in fdt

drivers/adc/Makefile

@@ -0,0 +1,8 @@
+#
+# Copyright (C) 2015 Samsung Electronics
+# Przemyslaw Marczak <p.marczak@samsung.com>
+#
+# SPDX-License-Identifier:     GPL-2.0+
+#
+
+obj-$(CONFIG_ADC) += adc-uclass.o

drivers/adc/adc-uclass.c

@@ -0,0 +1,409 @@
+/*
+ * Copyright (C) 2015 Samsung Electronics
+ * Przemyslaw Marczak <p.marczak@samsung.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <errno.h>
+#include <dm.h>
+#include <dm/lists.h>
+#include <dm/device-internal.h>
+#include <dm/uclass-internal.h>
+#include <adc.h>
+#include <power/regulator.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#define ADC_UCLASS_PLATDATA_SIZE	sizeof(struct adc_uclass_platdata)
+#define CHECK_NUMBER			true
+#define CHECK_MASK			(!CHECK_NUMBER)
+
+/* TODO: add support for timer uclass (for early calls) */
+#ifdef CONFIG_SANDBOX_ARCH
+#define sdelay(x)	udelay(x)
+#else
+extern void sdelay(unsigned long loops);
+#endif
+
+static int check_channel(struct udevice *dev, int value, bool number_or_mask,
+			 const char *caller_function)
+{
+	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
+	unsigned mask = number_or_mask ? (1 << value) : value;
+
+	/* For the real ADC hardware, some ADC channels can be inactive.
+	 * For example if device has 4 analog channels, and only channels
+	 * 1-st and 3-rd are valid, then channel mask is: 0b1010, so request
+	 * with mask 0b1110 should return an error.
+	*/
+	if ((uc_pdata->channel_mask >= mask) && (uc_pdata->channel_mask & mask))
+		return 0;
+
+	printf("Error in %s/%s().\nWrong channel selection for device: %s\n",
+	       __FILE__, caller_function, dev->name);
+
+	return -EINVAL;
+}
+
+static int adc_supply_enable(struct udevice *dev)
+{
+	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
+	const char *supply_type;
+	int ret = 0;
+
+	if (uc_pdata->vdd_supply) {
+		supply_type = "vdd";
+		ret = regulator_set_enable(uc_pdata->vdd_supply, true);
+	}
+
+	if (!ret && uc_pdata->vss_supply) {
+		supply_type = "vss";
+		ret = regulator_set_enable(uc_pdata->vss_supply, true);
+	}
+
+	if (ret)
+		error("%s: can't enable %s-supply!", dev->name, supply_type);
+
+	return ret;
+}
+
+int adc_data_mask(struct udevice *dev, unsigned int *data_mask)
+{
+	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
+
+	if (!uc_pdata)
+		return -ENOSYS;
+
+	*data_mask = uc_pdata->data_mask;
+	return 0;
+}
+
+int adc_stop(struct udevice *dev)
+{
+	const struct adc_ops *ops = dev_get_driver_ops(dev);
+
+	if (!ops->stop)
+		return -ENOSYS;
+
+	return ops->stop(dev);
+}
+
+int adc_start_channel(struct udevice *dev, int channel)
+{
+	const struct adc_ops *ops = dev_get_driver_ops(dev);
+	int ret;
+
+	if (!ops->start_channel)
+		return -ENOSYS;
+
+	ret = check_channel(dev, channel, CHECK_NUMBER, __func__);
+	if (ret)
+		return ret;
+
+	ret = adc_supply_enable(dev);
+	if (ret)
+		return ret;
+
+	return ops->start_channel(dev, channel);
+}
+
+int adc_start_channels(struct udevice *dev, unsigned int channel_mask)
+{
+	const struct adc_ops *ops = dev_get_driver_ops(dev);
+	int ret;
+
+	if (!ops->start_channels)
+		return -ENOSYS;
+
+	ret = check_channel(dev, channel_mask, CHECK_MASK, __func__);
+	if (ret)
+		return ret;
+
+	ret = adc_supply_enable(dev);
+	if (ret)
+		return ret;
+
+	return ops->start_channels(dev, channel_mask);
+}
+
+int adc_channel_data(struct udevice *dev, int channel, unsigned int *data)
+{
+	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
+	const struct adc_ops *ops = dev_get_driver_ops(dev);
+	unsigned int timeout_us = uc_pdata->data_timeout_us;
+	int ret;
+
+	if (!ops->channel_data)
+		return -ENOSYS;
+
+	ret = check_channel(dev, channel, CHECK_NUMBER, __func__);
+	if (ret)
+		return ret;
+
+	do {
+		ret = ops->channel_data(dev, channel, data);
+		if (!ret || ret != -EBUSY)
+			break;
+
+		/* TODO: use timer uclass (for early calls). */
+		sdelay(5);
+	} while (timeout_us--);
+
+	return ret;
+}
+
+int adc_channels_data(struct udevice *dev, unsigned int channel_mask,
+		      struct adc_channel *channels)
+{
+	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
+	unsigned int timeout_us = uc_pdata->multidata_timeout_us;
+	const struct adc_ops *ops = dev_get_driver_ops(dev);
+	int ret;
+
+	if (!ops->channels_data)
+		return -ENOSYS;
+
+	ret = check_channel(dev, channel_mask, CHECK_MASK, __func__);
+	if (ret)
+		return ret;
+
+	do {
+		ret = ops->channels_data(dev, channel_mask, channels);
+		if (!ret || ret != -EBUSY)
+			break;
+
+		/* TODO: use timer uclass (for early calls). */
+		sdelay(5);
+	} while (timeout_us--);
+
+	return ret;
+}
+
+int adc_channel_single_shot(const char *name, int channel, unsigned int *data)
+{
+	struct udevice *dev;
+	int ret;
+
+	ret = uclass_get_device_by_name(UCLASS_ADC, name, &dev);
+	if (ret)
+		return ret;
+
+	ret = adc_start_channel(dev, channel);
+	if (ret)
+		return ret;
+
+	ret = adc_channel_data(dev, channel, data);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int _adc_channels_single_shot(struct udevice *dev,
+				     unsigned int channel_mask,
+				     struct adc_channel *channels)
+{
+	unsigned int data;
+	int channel, ret;
+
+	for (channel = 0; channel <= ADC_MAX_CHANNEL; channel++) {
+		/* Check channel bit. */
+		if (!((channel_mask >> channel) & 0x1))
+			continue;
+
+		ret = adc_start_channel(dev, channel);
+		if (ret)
+			return ret;
+
+		ret = adc_channel_data(dev, channel, &data);
+		if (ret)
+			return ret;
+
+		channels->id = channel;
+		channels->data = data;
+		channels++;
+	}
+
+	return 0;
+}
+
+int adc_channels_single_shot(const char *name, unsigned int channel_mask,
+			     struct adc_channel *channels)
+{
+	struct udevice *dev;
+	int ret;
+
+	ret = uclass_get_device_by_name(UCLASS_ADC, name, &dev);
+	if (ret)
+		return ret;
+
+	ret = adc_start_channels(dev, channel_mask);
+	if (ret)
+		goto try_manual;
+
+	ret = adc_channels_data(dev, channel_mask, channels);
+	if (ret)
+		return ret;
+
+	return 0;
+
+try_manual:
+	if (ret != -ENOSYS)
+		return ret;
+
+	return _adc_channels_single_shot(dev, channel_mask, channels);
+}
+
+static int adc_vdd_platdata_update(struct udevice *dev)
+{
+	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
+	int ret;
+
+	/* Warning!
+	 * This function can't return supply device before its bind.
+	 * Please pay attention to proper fdt scan sequence. If ADC device
+	 * will bind before its supply regulator device, then the below 'get'
+	 * will return an error.
+	 */
+	ret = device_get_supply_regulator(dev, "vdd-supply",
+					  &uc_pdata->vdd_supply);
+	if (ret)
+		return ret;
+
+	ret = regulator_get_value(uc_pdata->vdd_supply);
+	if (ret < 0)
+		return ret;
+
+	uc_pdata->vdd_microvolts = ret;
+
+	return 0;
+}
+
+static int adc_vss_platdata_update(struct udevice *dev)
+{
+	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
+	int ret;
+
+	ret = device_get_supply_regulator(dev, "vss-supply",
+					  &uc_pdata->vss_supply);
+	if (ret)
+		return ret;
+
+	ret = regulator_get_value(uc_pdata->vss_supply);
+	if (ret < 0)
+		return ret;
+
+	uc_pdata->vss_microvolts = ret;
+
+	return 0;
+}
+
+int adc_vdd_value(struct udevice *dev, int *uV)
+{
+	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
+	int ret, value_sign = uc_pdata->vdd_polarity_negative ? -1 : 1;
+
+	if (!uc_pdata->vdd_supply)
+		goto nodev;
+
+	/* Update the regulator Value. */
+	ret = adc_vdd_platdata_update(dev);
+	if (ret)
+		return ret;
+nodev:
+	if (uc_pdata->vdd_microvolts == -ENODATA)
+		return -ENODATA;
+
+	*uV = uc_pdata->vdd_microvolts * value_sign;
+
+	return 0;
+}
+
+int adc_vss_value(struct udevice *dev, int *uV)
+{
+	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
+	int ret, value_sign = uc_pdata->vss_polarity_negative ? -1 : 1;
+
+	if (!uc_pdata->vss_supply)
+		goto nodev;
+
+	/* Update the regulator Value. */
+	ret = adc_vss_platdata_update(dev);
+	if (ret)
+		return ret;
+nodev:
+	if (uc_pdata->vss_microvolts == -ENODATA)
+		return -ENODATA;
+
+	*uV = uc_pdata->vss_microvolts * value_sign;
+
+	return 0;
+}
+
+static int adc_vdd_platdata_set(struct udevice *dev)
+{
+	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
+	int ret, offset = dev->of_offset;
+	const void *fdt = gd->fdt_blob;
+	char *prop;
+
+	prop = "vdd-polarity-negative";
+	uc_pdata->vdd_polarity_negative = fdtdec_get_bool(fdt, offset, prop);
+
+	ret = adc_vdd_platdata_update(dev);
+	if (ret != -ENOENT)
+		return ret;
+
+	/* No vdd-supply phandle. */
+	prop  = "vdd-microvolts";
+	uc_pdata->vdd_microvolts = fdtdec_get_int(fdt, offset, prop, -ENODATA);
+
+	return 0;
+}
+
+static int adc_vss_platdata_set(struct udevice *dev)
+{
+	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
+	int ret, offset = dev->of_offset;
+	const void *fdt = gd->fdt_blob;
+	char *prop;
+
+	prop = "vss-polarity-negative";
+	uc_pdata->vss_polarity_negative = fdtdec_get_bool(fdt, offset, prop);
+
+	ret = adc_vss_platdata_update(dev);
+	if (ret != -ENOENT)
+		return ret;
+
+	/* No vss-supply phandle. */
+	prop = "vss-microvolts";
+	uc_pdata->vss_microvolts = fdtdec_get_int(fdt, offset, prop, -ENODATA);
+
+	return 0;
+}
+
+static int adc_pre_probe(struct udevice *dev)
+{
+	int ret;
+
+	/* Set ADC VDD platdata: polarity, uV, regulator (phandle). */
+	ret = adc_vdd_platdata_set(dev);
+	if (ret)
+		error("%s: Can't update Vdd. Error: %d", dev->name, ret);
+
+	/* Set ADC VSS platdata: polarity, uV, regulator (phandle). */
+	ret = adc_vss_platdata_set(dev);
+	if (ret)
+		error("%s: Can't update Vss. Error: %d", dev->name, ret);
+
+	return 0;
+}
+
+UCLASS_DRIVER(adc) = {
+	.id	= UCLASS_ADC,
+	.name	= "adc",
+	.pre_probe =  adc_pre_probe,
+	.per_device_platdata_auto_alloc_size = ADC_UCLASS_PLATDATA_SIZE,
+};

include/adc.h

@@ -0,0 +1,288 @@
+/*
+ * Copyright (C) 2015 Samsung Electronics
+ * Przemyslaw Marczak <p.marczak@samsung.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef _ADC_H_
+#define _ADC_H_
+
+/* ADC_CHANNEL() - ADC channel bit mask, to select only required channels */
+#define ADC_CHANNEL(x)		(1 << x)
+
+/* The last possible selected channel with 32-bit mask */
+#define ADC_MAX_CHANNEL		31
+
+/**
+ * adc_data_format: define the ADC output data format, can be useful when
+ * the device's input Voltage range is bipolar.
+ * - ADC_DATA_FORMAT_BIN - binary offset
+ * - ADC_DATA_FORMAT_2S  - two's complement
+ *
+ * Note: Device's driver should fill the 'data_format' field of its uclass's
+ * platform data using one of the above data format types.
+ */
+enum adc_data_format {
+	ADC_DATA_FORMAT_BIN,
+	ADC_DATA_FORMAT_2S,
+};
+
+/**
+ * struct adc_channel - structure to hold channel conversion data.
+ * Useful to keep the result of a multi-channel conversion output.
+ *
+ * @id   - channel id
+ * @data - channel conversion data
+ */
+struct adc_channel {
+	int id;
+	unsigned int data;
+};
+
+/**
+ * struct adc_uclass_platdata - basic ADC info
+ *
+ * Note: The positive/negative reference Voltage is only a name and it doesn't
+ * provide an information about the value polarity. It is possible, for both
+ * values to be a negative or positive. For this purpose the uclass's platform
+ * data provides a bool fields: 'vdd/vss_supply_is_negative'. This is useful,
+ * since the regulator API returns only a positive Voltage values.
+ *
+ * To get the reference Voltage values with polarity, use functions:
+ * - adc_vdd_value()
+ * - adc_vss_value()
+ * Those are useful for some cases of ADC's references, e.g.:
+ * * Vdd: +3.3V; Vss: -3.3V -> 6.6 Vdiff
+ * * Vdd: +3.3V; Vss: +0.3V -> 3.0 Vdiff
+ * * Vdd: +3.3V; Vss:  0.0V -> 3.3 Vdiff
+ * The last one is usually standard and doesn't require the fdt polarity info.
+ *
+ * For more informations read binding info:
+ * - doc/device-tree-bindings/adc/adc.txt
+ *
+ * @data_mask              - conversion output data mask
+ * @data_timeout_us        - single channel conversion timeout
+ * @multidata_timeout_us   - multi channel conversion timeout
+ * @channel_mask           - bit mask of available channels [0:31]
+ * @vdd_supply             - positive reference Voltage supply (regulator)
+ * @vss_supply             - negative reference Voltage supply (regulator)
+ * @vdd_polarity_negative  - positive reference Voltage has negative polarity
+ * @vss_polarity_negative  - negative reference Voltage has negative polarity
+ * @vdd_microvolts         - positive reference Voltage value
+ * @vss_microvolts         - negative reference Voltage value
+ */
+struct adc_uclass_platdata {
+	int data_format;
+	unsigned int data_mask;
+	unsigned int data_timeout_us;
+	unsigned int multidata_timeout_us;
+	unsigned int channel_mask;
+	struct udevice *vdd_supply;
+	struct udevice *vss_supply;
+	bool vdd_polarity_negative;
+	bool vss_polarity_negative;
+	int vdd_microvolts;
+	int vss_microvolts;
+};
+
+/**
+ * struct adc_ops - ADC device operations for single/multi-channel operation.
+ */
+struct adc_ops {
+	/**
+	 * start_channel() - start conversion with its default parameters
+	 *                   for the given channel number.
+	 *
+	 * @dev:          ADC device to init
+	 * @channel:      analog channel number
+	 * @return:       0 if OK, -ve on error
+	 */
+	int (*start_channel)(struct udevice *dev, int channel);
+
+	/**
+	 * start_channels() - start conversion with its default parameters
+	 *                    for the channel numbers selected by the bit mask.
+	 *
+	 * This is optional, useful when the hardware supports multichannel
+	 * conversion by the single software trigger.
+	 *
+	 * @dev:          ADC device to init
+	 * @channel_mask: bit mask of selected analog channels
+	 * @return:       0 if OK, -ve on error
+	 */
+	int (*start_channels)(struct udevice *dev, unsigned int channel_mask);
+
+	/**
+	 * channel_data() - get conversion output data for the given channel.
+	 *
+	 * Note: The implementation of this function should only check, that
+	 * the conversion data is available at the call time. If the hardware
+	 * requires some delay to get the data, then this function should
+	 * return with -EBUSY value. The ADC API will call it in a loop,
+	 * until the data is available or the timeout expires. The maximum
+	 * timeout for this operation is defined by the field 'data_timeout_us'
+	 * in ADC uclasses platform data structure.
+	 *
+	 * @dev:          ADC device to trigger
+	 * @channel:      selected analog channel number
+	 * @data:         returned pointer to selected channel's output data
+	 * @return:       0 if OK, -EBUSY if busy, and other negative on error
+	 */
+	int (*channel_data)(struct udevice *dev, int channel,
+			    unsigned int *data);
+
+	/**
+	 * channels_data() - get conversion data for the selected channels.
+	 *
+	 * This is optional, useful when multichannel conversion is supported
+	 * by the hardware, by the single software trigger.
+	 *
+	 * For the proper implementation, please look at the 'Note' for the
+	 * above method. The only difference is in used timeout value, which
+	 * is defined by field 'multidata_timeout_us'.
+	 *
+	 * @dev:          ADC device to trigger
+	 * @channel_mask: bit mask of selected analog channels
+	 * @channels:     returned pointer to array of output data for channels
+	 *                selected by the given mask
+	 * @return:       0 if OK, -ve on error
+	 */
+	int (*channels_data)(struct udevice *dev, unsigned int channel_mask,
+			     struct adc_channel *channels);
+
+	/**
+	 * stop() - stop conversion of the given ADC device
+	 *
+	 * @dev:          ADC device to stop
+	 * @return:       0 if OK, -ve on error
+	 */
+	int (*stop)(struct udevice *dev);
+};
+
+/**
+ * adc_start_channel() - start conversion for given device/channel and exit.
+ *
+ * @dev:     ADC device
+ * @channel: analog channel number
+ * @return:  0 if OK, -ve on error
+ */
+int adc_start_channel(struct udevice *dev, int channel);
+
+/**
+ * adc_start_channels() - start conversion for given device/channels and exit.
+ *
+ * Note:
+ * To use this function, device must implement method: start_channels().
+ *
+ * @dev:          ADC device to start
+ * @channel_mask: channel selection - a bit mask
+ * @channel_mask: bit mask of analog channels
+ * @return:       0 if OK, -ve on error
+ */
+int adc_start_channels(struct udevice *dev, unsigned int channel_mask);
+
+/**
+ * adc_channel_data() - get conversion data for the given device channel number.
+ *
+ * @dev:     ADC device to read
+ * @channel: analog channel number
+ * @data:    pointer to returned channel's data
+ * @return:  0 if OK, -ve on error
+ */
+int adc_channel_data(struct udevice *dev, int channel, unsigned int *data);
+
+/**
+ * adc_channels_data() - get conversion data for the channels selected by mask
+ *
+ * Note:
+ * To use this function, device must implement methods:
+ * - start_channels()
+ * - channels_data()
+ *
+ * @dev:          ADC device to read
+ * @channel_mask: channel selection - a bit mask
+ * @channels:     pointer to structure array of returned data for each channel
+ * @return:       0 if OK, -ve on error
+ */
+int adc_channels_data(struct udevice *dev, unsigned int channel_mask,
+		      struct adc_channel *channels);
+
+/**
+ * adc_data_mask() - get data mask (ADC resolution bitmask) for given ADC device
+ *
+ * This can be used if adc uclass platform data is filled.
+ *
+ * @dev:       ADC device to check
+ * @data_mask: pointer to the returned data bitmask
+ * @return: 0 if OK, -ve on error
+ */
+int adc_data_mask(struct udevice *dev, unsigned int *data_mask);
+
+/**
+ * adc_channel_single_shot() - get output data of conversion for the ADC
+ * device's channel. This function searches for the device with the given name,
+ * starts the given channel conversion and returns the output data.
+ *
+ * Note: To use this function, device must implement metods:
+ * - start_channel()
+ * - channel_data()
+ *
+ * @name:    device's name to search
+ * @channel: device's input channel to init
+ * @data:    pointer to conversion output data
+ * @return:  0 if OK, -ve on error
+ */
+int adc_channel_single_shot(const char *name, int channel, unsigned int *data);
+
+/**
+ * adc_channels_single_shot() - get ADC conversion output data for the selected
+ * device's channels. This function searches for the device by the given name,
+ * starts the selected channels conversion and returns the output data as array
+ * of type 'struct adc_channel'.
+ *
+ * Note: This function can be used if device implements one of ADC's single
+ * or multi-channel operation API. If multi-channel operation is not supported,
+ * then each selected channel is triggered by the sequence start/data in a loop.
+ *
+ * @name:         device's name to search
+ * @channel_mask: channel selection - a bit mask
+ * @channels:     pointer to conversion output data for the selected channels
+ * @return:       0 if OK, -ve on error
+ */
+int adc_channels_single_shot(const char *name, unsigned int channel_mask,
+			     struct adc_channel *channels);
+
+/**
+ * adc_vdd_value() - get the ADC device's positive reference Voltage value
+ *
+ * Note: Depending on bool value 'vdd_supply_is_negative' of platform data,
+ * the returned uV value can be negative, and it's not an error.
+ *
+ * @dev:     ADC device to check
+ * @uV:      Voltage value with polarization sign (uV)
+ * @return:  0 on success or -ve on error
+*/
+int adc_vdd_value(struct udevice *dev, int *uV);
+
+/**
+ * adc_vss_value() - get the ADC device's negative reference Voltage value
+ *
+ * Note: Depending on bool value 'vdd_supply_is_negative' of platform data,
+ * the returned uV value can be negative, and it's not an error.
+ *
+ * @dev:     ADC device to check
+ * @uV:      Voltage value with polarization sign (uV)
+ * @return:  0 on success or -ve on error
+*/
+int adc_vss_value(struct udevice *dev, int *uV);
+
+/**
+ * adc_stop() - stop operation for given ADC device.
+ *
+ * @dev:     ADC device to stop
+ * @return:  0 if OK, -ve on error
+ */
+int adc_stop(struct udevice *dev);
+
+#endif

include/dm/uclass-id.h

@@ -25,6 +25,7 @@ enum uclass_id {
 	UCLASS_SIMPLE_BUS,	/* bus with child devices */
 
 	/* U-Boot uclasses start here - in alphabetical order */
+	UCLASS_ADC,		/* Analog-to-digital converter */
 	UCLASS_CLK,		/* Clock source, e.g. used by peripherals */
 	UCLASS_CPU,		/* CPU, typically part of an SoC */
 	UCLASS_CROS_EC,		/* Chrome OS EC */