iio: adc: add ADC12130/ADC12132/ADC12138 ADC driver

This adds Texas Instruments' ADC12130/ADC12132/ADC12138 12-bit plus
sign ADC driver.  I have tested with the ADC12138.  The ADC12130 and
ADC12132 are not tested but these are similar to ADC12138 except that
the mode programming instruction is a bit different.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/devicetree/bindings/iio/adc/ti-adc12138.txt

+* Texas Instruments' ADC12130/ADC12132/ADC12138
+
+Required properties:
+ - compatible: Should be one of
+	* "ti,adc12130"
+	* "ti,adc12132"
+	* "ti,adc12138"
+ - reg: SPI chip select number for the device
+ - interrupts: Should contain interrupt for EOC (end of conversion)
+ - clocks: phandle to conversion clock input
+ - spi-max-frequency: Definision as per
+	Documentation/devicetree/bindings/spi/spi-bus.txt
+ - vref-p-supply: The regulator supply for positive analog voltage reference
+
+Optional properties:
+ - vref-n-supply: The regulator supply for negative analog voltage reference
+	(Note that this must not go below GND or exceed vref-p)
+	If not specified, this is assumed to be analog ground.
+ - ti,acquisition-time: The number of conversion clock periods for the S/H's
+	acquisition time.  Should be one of 6, 10, 18, 34.  If not specified,
+	default value of 10 is used.
+	For high source impedances, this value can be increased to 18 or 34.
+	For less ADC accuracy and/or slower CCLK frequencies this value may be
+	decreased to 6.  See section 6.0 INPUT SOURCE RESISTANCE in the
+	datasheet for details.
+
+Example:
+adc@0 {
+	compatible = "ti,adc12138";
+	reg = <0>;
+	interrupts = <28 IRQ_TYPE_EDGE_RISING>;
+	interrupt-parent = <&gpio1>;
+	clocks = <&cclk>;
+	vref-p-supply = <&ldo4_reg>;
+	spi-max-frequency = <5000000>;
+	ti,acquisition-time = <6>;
+};

drivers/iio/adc/Kconfig

@@ -438,6 +438,18 @@ config TI_ADC0832
 	  This driver can also be built as a module. If so, the module will be
 	  called ti-adc0832.
 
+config TI_ADC12138
+	tristate "Texas Instruments ADC12130/ADC12132/ADC12138"
+	depends on SPI
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  If you say yes here you get support for Texas Instruments ADC12130,
+	  ADC12132 and ADC12138 chips.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called ti-adc12138.
+
 config TI_ADC128S052
 	tristate "Texas Instruments ADC128S052/ADC122S021/ADC124S021"
 	depends on SPI

drivers/iio/adc/Makefile

@@ -42,6 +42,7 @@ obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
 obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
+obj-$(CONFIG_TI_ADC12138) += ti-adc12138.o
 obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
 obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
 obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o

drivers/iio/adc/ti-adc12138.c

+/*
+ * ADC12130/ADC12132/ADC12138 12-bit plus sign ADC driver
+ *
+ * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
+ *
+ * This file is subject to the terms and conditions of version 2 of
+ * the GNU General Public License.  See the file COPYING in the main
+ * directory of this archive for more details.
+ *
+ * Datasheet: http://www.ti.com/lit/ds/symlink/adc12138.pdf
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
+#include <linux/clk.h>
+#include <linux/spi/spi.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/regulator/consumer.h>
+
+#define ADC12138_MODE_AUTO_CAL			0x08
+#define ADC12138_MODE_READ_STATUS		0x0c
+#define ADC12138_MODE_ACQUISITION_TIME_6	0x0e
+#define ADC12138_MODE_ACQUISITION_TIME_10	0x4e
+#define ADC12138_MODE_ACQUISITION_TIME_18	0x8e
+#define ADC12138_MODE_ACQUISITION_TIME_34	0xce
+
+#define ADC12138_STATUS_CAL			BIT(6)
+
+enum {
+	adc12130,
+	adc12132,
+	adc12138,
+};
+
+struct adc12138 {
+	struct spi_device *spi;
+	unsigned int id;
+	/* conversion clock */
+	struct clk *cclk;
+	/* positive analog voltage reference */
+	struct regulator *vref_p;
+	/* negative analog voltage reference */
+	struct regulator *vref_n;
+	struct mutex lock;
+	struct completion complete;
+	/* The number of cclk periods for the S/H's acquisition time */
+	unsigned int acquisition_time;
+
+	u8 tx_buf[2] ____cacheline_aligned;
+	u8 rx_buf[2];
+};
+
+#define ADC12138_VOLTAGE_CHANNEL(chan)					\
+	{								\
+		.type = IIO_VOLTAGE,					\
+		.indexed = 1,						\
+		.channel = chan,					\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)	\
+					| BIT(IIO_CHAN_INFO_OFFSET),	\
+		.scan_index = chan,					\
+		.scan_type = {						\
+			.sign = 's',					\
+			.realbits = 13,					\
+			.storagebits = 16,				\
+			.shift = 3,					\
+			.endianness = IIO_BE,				\
+		},							\
+	}
+
+#define ADC12138_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si)			\
+	{								\
+		.type = IIO_VOLTAGE,					\
+		.indexed = 1,						\
+		.channel = (chan1),					\
+		.channel2 = (chan2),					\
+		.differential = 1,					\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)	\
+					| BIT(IIO_CHAN_INFO_OFFSET),	\
+		.scan_index = si,					\
+		.scan_type = {						\
+			.sign = 's',					\
+			.realbits = 13,					\
+			.storagebits = 16,				\
+			.shift = 3,					\
+			.endianness = IIO_BE,				\
+		},							\
+	}
+
+static const struct iio_chan_spec adc12132_channels[] = {
+	ADC12138_VOLTAGE_CHANNEL(0),
+	ADC12138_VOLTAGE_CHANNEL(1),
+	ADC12138_VOLTAGE_CHANNEL_DIFF(0, 1, 2),
+	ADC12138_VOLTAGE_CHANNEL_DIFF(1, 0, 3),
+	IIO_CHAN_SOFT_TIMESTAMP(4),
+};
+
+static const struct iio_chan_spec adc12138_channels[] = {
+	ADC12138_VOLTAGE_CHANNEL(0),
+	ADC12138_VOLTAGE_CHANNEL(1),
+	ADC12138_VOLTAGE_CHANNEL(2),
+	ADC12138_VOLTAGE_CHANNEL(3),
+	ADC12138_VOLTAGE_CHANNEL(4),
+	ADC12138_VOLTAGE_CHANNEL(5),
+	ADC12138_VOLTAGE_CHANNEL(6),
+	ADC12138_VOLTAGE_CHANNEL(7),
+	ADC12138_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
+	ADC12138_VOLTAGE_CHANNEL_DIFF(1, 0, 9),
+	ADC12138_VOLTAGE_CHANNEL_DIFF(2, 3, 10),
+	ADC12138_VOLTAGE_CHANNEL_DIFF(3, 2, 11),
+	ADC12138_VOLTAGE_CHANNEL_DIFF(4, 5, 12),
+	ADC12138_VOLTAGE_CHANNEL_DIFF(5, 4, 13),
+	ADC12138_VOLTAGE_CHANNEL_DIFF(6, 7, 14),
+	ADC12138_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
+	IIO_CHAN_SOFT_TIMESTAMP(16),
+};
+
+static int adc12138_mode_programming(struct adc12138 *adc, u8 mode,
+				     void *rx_buf, int len)
+{
+	struct spi_transfer xfer = {
+		.tx_buf = adc->tx_buf,
+		.rx_buf = adc->rx_buf,
+		.len = len,
+	};
+	int ret;
+
+	/* Skip unused bits for ADC12130 and ADC12132 */
+	if (adc->id != adc12138)
+		mode = (mode & 0xc0) | ((mode & 0x0f) << 2);
+
+	adc->tx_buf[0] = mode;
+
+	ret = spi_sync_transfer(adc->spi, &xfer, 1);
+	if (ret)
+		return ret;
+
+	memcpy(rx_buf, adc->rx_buf, len);
+
+	return 0;
+}
+
+static int adc12138_read_status(struct adc12138 *adc)
+{
+	u8 rx_buf[2];
+	int ret;
+
+	ret = adc12138_mode_programming(adc, ADC12138_MODE_READ_STATUS,
+					rx_buf, 2);
+	if (ret)
+		return ret;
+
+	return (rx_buf[0] << 1) | (rx_buf[1] >> 7);
+}
+
+static int __adc12138_start_conv(struct adc12138 *adc,
+				 struct iio_chan_spec const *channel,
+				 void *data, int len)
+
+{
+	const u8 ch_to_mux[] = { 0, 4, 1, 5, 2, 6, 3, 7 };
+	u8 mode = (ch_to_mux[channel->channel] << 4) |
+		  (channel->differential ? 0 : 0x80);
+
+	return adc12138_mode_programming(adc, mode, data, len);
+}
+
+static int adc12138_start_conv(struct adc12138 *adc,
+			       struct iio_chan_spec const *channel)
+{
+	u8 trash;
+
+	return __adc12138_start_conv(adc, channel, &trash, 1);
+}
+
+static int adc12138_start_and_read_conv(struct adc12138 *adc,
+					struct iio_chan_spec const *channel,
+					__be16 *data)
+{
+	return __adc12138_start_conv(adc, channel, data, 2);
+}
+
+static int adc12138_read_conv_data(struct adc12138 *adc, __be16 *value)
+{
+	/* Issue a read status instruction and read previous conversion data */
+	return adc12138_mode_programming(adc, ADC12138_MODE_READ_STATUS,
+					 value, sizeof(*value));
+}
+
+static int adc12138_wait_eoc(struct adc12138 *adc, unsigned long timeout)
+{
+	if (!wait_for_completion_timeout(&adc->complete, timeout))
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static int adc12138_adc_conversion(struct adc12138 *adc,
+				   struct iio_chan_spec const *channel,
+				   __be16 *value)
+{
+	int ret;
+
+	reinit_completion(&adc->complete);
+
+	ret = adc12138_start_conv(adc, channel);
+	if (ret)
+		return ret;
+
+	ret = adc12138_wait_eoc(adc, msecs_to_jiffies(100));
+	if (ret)
+		return ret;
+
+	return adc12138_read_conv_data(adc, value);
+}
+
+static int adc12138_read_raw(struct iio_dev *iio,
+			     struct iio_chan_spec const *channel, int *value,
+			     int *shift, long mask)
+{
+	struct adc12138 *adc = iio_priv(iio);
+	int ret;
+	__be16 data;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&adc->lock);
+		ret = adc12138_adc_conversion(adc, channel, &data);
+		mutex_unlock(&adc->lock);
+		if (ret)
+			return ret;
+
+		*value = sign_extend32(be16_to_cpu(data) >> 3, 12);
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		ret = regulator_get_voltage(adc->vref_p);
+		if (ret < 0)
+			return ret;
+		*value = ret;
+
+		if (!IS_ERR(adc->vref_n)) {
+			ret = regulator_get_voltage(adc->vref_n);
+			if (ret < 0)
+				return ret;
+			*value -= ret;
+		}
+
+		/* convert regulator output voltage to mV */
+		*value /= 1000;
+		*shift = channel->scan_type.realbits - 1;
+
+		return IIO_VAL_FRACTIONAL_LOG2;
+	case IIO_CHAN_INFO_OFFSET:
+		if (!IS_ERR(adc->vref_n)) {
+			*value = regulator_get_voltage(adc->vref_n);
+			if (*value < 0)
+				return *value;
+		} else {
+			*value = 0;
+		}
+
+		/* convert regulator output voltage to mV */
+		*value /= 1000;
+
+		return IIO_VAL_INT;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info adc12138_info = {
+	.read_raw = adc12138_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static int adc12138_init(struct adc12138 *adc)
+{
+	int ret;
+	int status;
+	u8 mode;
+	u8 trash;
+
+	reinit_completion(&adc->complete);
+
+	ret = adc12138_mode_programming(adc, ADC12138_MODE_AUTO_CAL, &trash, 1);
+	if (ret)
+		return ret;
+
+	/* data output at this time has no significance */
+	status = adc12138_read_status(adc);
+	if (status < 0)
+		return status;
+
+	adc12138_wait_eoc(adc, msecs_to_jiffies(100));
+
+	status = adc12138_read_status(adc);
+	if (status & ADC12138_STATUS_CAL) {
+		dev_warn(&adc->spi->dev,
+			"Auto Cal sequence is still in progress: %#x\n",
+			status);
+		return -EIO;
+	}
+
+	switch (adc->acquisition_time) {
+	case 6:
+		mode = ADC12138_MODE_ACQUISITION_TIME_6;
+		break;
+	case 10:
+		mode = ADC12138_MODE_ACQUISITION_TIME_10;
+		break;
+	case 18:
+		mode = ADC12138_MODE_ACQUISITION_TIME_18;
+		break;
+	case 34:
+		mode = ADC12138_MODE_ACQUISITION_TIME_34;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return adc12138_mode_programming(adc, mode, &trash, 1);
+}
+
+static irqreturn_t adc12138_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct adc12138 *adc = iio_priv(indio_dev);
+	__be16 data[20] = { }; /* 16x 2 bytes ADC data + 8 bytes timestamp */
+	__be16 trash;
+	int ret;
+	int scan_index;
+	int i = 0;
+
+	mutex_lock(&adc->lock);
+
+	for_each_set_bit(scan_index, indio_dev->active_scan_mask,
+			 indio_dev->masklength) {
+		const struct iio_chan_spec *scan_chan =
+				&indio_dev->channels[scan_index];
+
+		reinit_completion(&adc->complete);
+
+		ret = adc12138_start_and_read_conv(adc, scan_chan,
+						   i ? &data[i - 1] : &trash);
+		if (ret) {
+			dev_warn(&adc->spi->dev,
+				 "failed to start conversion\n");
+			goto out;
+		}
+
+		ret = adc12138_wait_eoc(adc, msecs_to_jiffies(100));
+		if (ret) {
+			dev_warn(&adc->spi->dev, "wait eoc timeout\n");
+			goto out;
+		}
+
+		i++;
+	}
+
+	if (i) {
+		ret = adc12138_read_conv_data(adc, &data[i - 1]);
+		if (ret) {
+			dev_warn(&adc->spi->dev,
+				 "failed to get conversion data\n");
+			goto out;
+		}
+	}
+
+	iio_push_to_buffers_with_timestamp(indio_dev, data,
+					   iio_get_time_ns(indio_dev));
+out:
+	mutex_unlock(&adc->lock);
+
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t adc12138_eoc_handler(int irq, void *p)
+{
+	struct iio_dev *indio_dev = p;
+	struct adc12138 *adc = iio_priv(indio_dev);
+
+	complete(&adc->complete);
+
+	return IRQ_HANDLED;
+}
+
+static int adc12138_probe(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev;
+	struct adc12138 *adc;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	adc = iio_priv(indio_dev);
+	adc->spi = spi;
+	adc->id = spi_get_device_id(spi)->driver_data;
+	mutex_init(&adc->lock);
+	init_completion(&adc->complete);
+
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->info = &adc12138_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	switch (adc->id) {
+	case adc12130:
+	case adc12132:
+		indio_dev->channels = adc12132_channels;
+		indio_dev->num_channels = ARRAY_SIZE(adc12132_channels);
+		break;
+	case adc12138:
+		indio_dev->channels = adc12138_channels;
+		indio_dev->num_channels = ARRAY_SIZE(adc12138_channels);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = of_property_read_u32(spi->dev.of_node, "ti,acquisition-time",
+				   &adc->acquisition_time);
+	if (ret)
+		adc->acquisition_time = 10;
+
+	adc->cclk = devm_clk_get(&spi->dev, NULL);
+	if (IS_ERR(adc->cclk))
+		return PTR_ERR(adc->cclk);
+
+	adc->vref_p = devm_regulator_get(&spi->dev, "vref-p");
+	if (IS_ERR(adc->vref_p))
+		return PTR_ERR(adc->vref_p);
+
+	adc->vref_n = devm_regulator_get_optional(&spi->dev, "vref-n");
+	if (IS_ERR(adc->vref_n)) {
+		/*
+		 * Assume vref_n is 0V if an optional regulator is not
+		 * specified, otherwise return the error code.
+		 */
+		ret = PTR_ERR(adc->vref_n);
+		if (ret != -ENODEV)
+			return ret;
+	}
+
+	ret = devm_request_irq(&spi->dev, spi->irq, adc12138_eoc_handler,
+			       IRQF_TRIGGER_RISING, indio_dev->name, indio_dev);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(adc->cclk);
+	if (ret)
+		return ret;
+
+	ret = regulator_enable(adc->vref_p);
+	if (ret)
+		goto err_clk_disable;
+
+	if (!IS_ERR(adc->vref_n)) {
+		ret = regulator_enable(adc->vref_n);
+		if (ret)
+			goto err_vref_p_disable;
+	}
+
+	ret = adc12138_init(adc);
+	if (ret)
+		goto err_vref_n_disable;
+
+	spi_set_drvdata(spi, indio_dev);
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+					 adc12138_trigger_handler, NULL);
+	if (ret)
+		goto err_vref_n_disable;
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto err_buffer_cleanup;
+
+	return 0;
+err_buffer_cleanup:
+	iio_triggered_buffer_cleanup(indio_dev);
+err_vref_n_disable:
+	if (!IS_ERR(adc->vref_n))
+		regulator_disable(adc->vref_n);
+err_vref_p_disable:
+	regulator_disable(adc->vref_p);
+err_clk_disable:
+	clk_disable_unprepare(adc->cclk);
+
+	return ret;
+}
+
+static int adc12138_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct adc12138 *adc = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+	if (!IS_ERR(adc->vref_n))
+		regulator_disable(adc->vref_n);
+	regulator_disable(adc->vref_p);
+	clk_disable_unprepare(adc->cclk);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+
+static const struct of_device_id adc12138_dt_ids[] = {
+	{ .compatible = "ti,adc12130", },
+	{ .compatible = "ti,adc12132", },
+	{ .compatible = "ti,adc12138", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, adc12138_dt_ids);
+
+#endif
+
+static const struct spi_device_id adc12138_id[] = {
+	{ "adc12130", adc12130 },
+	{ "adc12132", adc12132 },
+	{ "adc12138", adc12138 },
+	{}
+};
+MODULE_DEVICE_TABLE(spi, adc12138_id);
+
+static struct spi_driver adc12138_driver = {
+	.driver = {
+		.name = "adc12138",
+		.of_match_table = of_match_ptr(adc12138_dt_ids),
+	},
+	.probe = adc12138_probe,
+	.remove = adc12138_remove,
+	.id_table = adc12138_id,
+};
+module_spi_driver(adc12138_driver);
+
+MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
+MODULE_DESCRIPTION("ADC12130/ADC12132/ADC12138 driver");
+MODULE_LICENSE("GPL v2");