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>

3 files changed, 429 insertions, 0 deletions

diff --git a/drivers/adc/Kconfig b/drivers/adc/Kconfig
new file mode 100644
index 0000000..b6e226a
--- /dev/null
+++ b/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
diff --git a/drivers/adc/Makefile b/drivers/adc/Makefile
new file mode 100644
index 0000000..c4d9618
--- /dev/null
+++ b/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
diff --git a/drivers/adc/adc-uclass.c b/drivers/adc/adc-uclass.c
new file mode 100644
index 0000000..9233fcd
--- /dev/null
+++ b/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,
+};