iio:adc: Add AD7265/AD7266 support

This patch adds support for the Analog Devices AD7265 and AD7266
Analog-to-Digital converters.

Signed-off-by: Lars-Peter Clausen <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/Kconfig

···
 #
 menu "Analog to digital converters"
 
+config AD7266
+	tristate "Analog Devices AD7265/AD7266 ADC driver"
+	depends on SPI_MASTER
+	select IIO_BUFFER
+	select IIO_TRIGGER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for Analog Devices AD7265 and AD7266
+	  ADCs.
+
 config AT91_ADC
 	tristate "Atmel AT91 ADC"
 	depends on ARCH_AT91

drivers/iio/adc/Makefile

···
 # Makefile for IIO ADC drivers
 #
 
+obj-$(CONFIG_AD7266) += ad7266.o
 obj-$(CONFIG_AT91_ADC) += at91_adc.o

drivers/iio/adc/ad7266.c

···
+/*
+ * AD7266/65 SPI ADC driver
+ *
+ * Copyright 2012 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/regulator/consumer.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/module.h>
+
+#include <linux/interrupt.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+#include <linux/platform_data/ad7266.h>
+
+struct ad7266_state {
+	struct spi_device	*spi;
+	struct regulator	*reg;
+	unsigned long		vref_uv;
+
+	struct spi_transfer	single_xfer[3];
+	struct spi_message	single_msg;
+
+	enum ad7266_range	range;
+	enum ad7266_mode	mode;
+	bool			fixed_addr;
+	struct gpio		gpios[3];
+
+	/*
+	 * DMA (thus cache coherency maintenance) requires the
+	 * transfer buffers to live in their own cache lines.
+	 * The buffer needs to be large enough to hold two samples (4 bytes) and
+	 * the naturally aligned timestamp (8 bytes).
+	 */
+	uint8_t data[ALIGN(4, sizeof(s64)) + sizeof(s64)] ____cacheline_aligned;
+};
+
+static int ad7266_wakeup(struct ad7266_state *st)
+{
+	/* Any read with >= 2 bytes will wake the device */
+	return spi_read(st->spi, st->data, 2);
+}
+
+static int ad7266_powerdown(struct ad7266_state *st)
+{
+	/* Any read with < 2 bytes will powerdown the device */
+	return spi_read(st->spi, st->data, 1);
+}
+
+static int ad7266_preenable(struct iio_dev *indio_dev)
+{
+	struct ad7266_state *st = iio_priv(indio_dev);
+	int ret;
+
+	ret = ad7266_wakeup(st);
+	if (ret)
+		return ret;
+
+	ret = iio_sw_buffer_preenable(indio_dev);
+	if (ret)
+		ad7266_powerdown(st);
+
+	return ret;
+}
+
+static int ad7266_postdisable(struct iio_dev *indio_dev)
+{
+	struct ad7266_state *st = iio_priv(indio_dev);
+	return ad7266_powerdown(st);
+}
+
+static const struct iio_buffer_setup_ops iio_triggered_buffer_setup_ops = {
+	.preenable = &ad7266_preenable,
+	.postenable = &iio_triggered_buffer_postenable,
+	.predisable = &iio_triggered_buffer_predisable,
+	.postdisable = &ad7266_postdisable,
+};
+
+static irqreturn_t ad7266_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct iio_buffer *buffer = indio_dev->buffer;
+	struct ad7266_state *st = iio_priv(indio_dev);
+	int ret;
+
+	ret = spi_read(st->spi, st->data, 4);
+	if (ret == 0) {
+		if (indio_dev->scan_timestamp)
+			((s64 *)st->data)[1] = pf->timestamp;
+		iio_push_to_buffer(buffer, (u8 *)st->data, pf->timestamp);
+	}
+
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static void ad7266_select_input(struct ad7266_state *st, unsigned int nr)
+{
+	unsigned int i;
+
+	if (st->fixed_addr)
+		return;
+
+	switch (st->mode) {
+	case AD7266_MODE_SINGLE_ENDED:
+		nr >>= 1;
+		break;
+	case AD7266_MODE_PSEUDO_DIFF:
+		nr |= 1;
+		break;
+	case AD7266_MODE_DIFF:
+		nr &= ~1;
+		break;
+	}
+
+	for (i = 0; i < 3; ++i)
+		gpio_set_value(st->gpios[i].gpio, (bool)(nr & BIT(i)));
+}
+
+static int ad7266_update_scan_mode(struct iio_dev *indio_dev,
+	const unsigned long *scan_mask)
+{
+	struct ad7266_state *st = iio_priv(indio_dev);
+	unsigned int nr = find_first_bit(scan_mask, indio_dev->masklength);
+
+	ad7266_select_input(st, nr);
+
+	return 0;
+}
+
+static int ad7266_read_single(struct ad7266_state *st, int *val,
+	unsigned int address)
+{
+	int ret;
+
+	ad7266_select_input(st, address);
+
+	ret = spi_sync(st->spi, &st->single_msg);
+	*val = be16_to_cpu(st->data[address % 2]);
+
+	return ret;
+}
+
+static int ad7266_read_raw(struct iio_dev *indio_dev,
+	struct iio_chan_spec const *chan, int *val, int *val2, long m)
+{
+	struct ad7266_state *st = iio_priv(indio_dev);
+	unsigned long scale_uv;
+	int ret;
+
+	switch (m) {
+	case IIO_CHAN_INFO_RAW:
+		if (iio_buffer_enabled(indio_dev))
+			return -EBUSY;
+
+		ret = ad7266_read_single(st, val, chan->address);
+		if (ret)
+			return ret;
+
+		*val = (*val >> 2) & 0xfff;
+		if (chan->scan_type.sign == 's')
+			*val = sign_extend32(*val, 11);
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		scale_uv = (st->vref_uv * 100);
+		if (st->mode == AD7266_MODE_DIFF)
+			scale_uv *= 2;
+		if (st->range == AD7266_RANGE_2VREF)
+			scale_uv *= 2;
+
+		scale_uv >>= chan->scan_type.realbits;
+		*val =  scale_uv / 100000;
+		*val2 = (scale_uv % 100000) * 10;
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_OFFSET:
+		if (st->range == AD7266_RANGE_2VREF &&
+			st->mode != AD7266_MODE_DIFF)
+			*val = 2048;
+		else
+			*val = 0;
+		return IIO_VAL_INT;
+	}
+	return -EINVAL;
+}
+
+#define AD7266_CHAN(_chan, _sign) {			\
+	.type = IIO_VOLTAGE,				\
+	.indexed = 1,					\
+	.channel = (_chan),				\
+	.address = (_chan),				\
+	.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT	\
+		| IIO_CHAN_INFO_SCALE_SHARED_BIT	\
+		| IIO_CHAN_INFO_OFFSET_SHARED_BIT,	\
+	.scan_index = (_chan),				\
+	.scan_type = {					\
+		.sign = (_sign),			\
+		.realbits = 12,				\
+		.storagebits = 16,			\
+		.shift = 2,				\
+		.endianness = IIO_BE,			\
+	},						\
+}
+
+#define AD7266_DECLARE_SINGLE_ENDED_CHANNELS(_name, _sign) \
+const struct iio_chan_spec ad7266_channels_##_name[] = { \
+	AD7266_CHAN(0, (_sign)), \
+	AD7266_CHAN(1, (_sign)), \
+	AD7266_CHAN(2, (_sign)), \
+	AD7266_CHAN(3, (_sign)), \
+	AD7266_CHAN(4, (_sign)), \
+	AD7266_CHAN(5, (_sign)), \
+	AD7266_CHAN(6, (_sign)), \
+	AD7266_CHAN(7, (_sign)), \
+	AD7266_CHAN(8, (_sign)), \
+	AD7266_CHAN(9, (_sign)), \
+	AD7266_CHAN(10, (_sign)), \
+	AD7266_CHAN(11, (_sign)), \
+	IIO_CHAN_SOFT_TIMESTAMP(13), \
+}
+
+#define AD7266_DECLARE_SINGLE_ENDED_CHANNELS_FIXED(_name, _sign) \
+const struct iio_chan_spec ad7266_channels_##_name##_fixed[] = { \
+	AD7266_CHAN(0, (_sign)), \
+	AD7266_CHAN(1, (_sign)), \
+	IIO_CHAN_SOFT_TIMESTAMP(2), \
+}
+
+static AD7266_DECLARE_SINGLE_ENDED_CHANNELS(u, 'u');
+static AD7266_DECLARE_SINGLE_ENDED_CHANNELS(s, 's');
+static AD7266_DECLARE_SINGLE_ENDED_CHANNELS_FIXED(u, 'u');
+static AD7266_DECLARE_SINGLE_ENDED_CHANNELS_FIXED(s, 's');
+
+#define AD7266_CHAN_DIFF(_chan, _sign) {			\
+	.type = IIO_VOLTAGE,				\
+	.indexed = 1,					\
+	.channel = (_chan) * 2,				\
+	.channel2 = (_chan) * 2 + 1,			\
+	.address = (_chan),				\
+	.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT	\
+		| IIO_CHAN_INFO_SCALE_SHARED_BIT	\
+		| IIO_CHAN_INFO_OFFSET_SHARED_BIT,	\
+	.scan_index = (_chan),				\
+	.scan_type = {					\
+		.sign = _sign,			\
+		.realbits = 12,				\
+		.storagebits = 16,			\
+		.shift = 2,				\
+		.endianness = IIO_BE,			\
+	},						\
+	.differential = 1,				\
+}
+
+#define AD7266_DECLARE_DIFF_CHANNELS(_name, _sign) \
+const struct iio_chan_spec ad7266_channels_diff_##_name[] = { \
+	AD7266_CHAN_DIFF(0, (_sign)), \
+	AD7266_CHAN_DIFF(1, (_sign)), \
+	AD7266_CHAN_DIFF(2, (_sign)), \
+	AD7266_CHAN_DIFF(3, (_sign)), \
+	AD7266_CHAN_DIFF(4, (_sign)), \
+	AD7266_CHAN_DIFF(5, (_sign)), \
+	IIO_CHAN_SOFT_TIMESTAMP(6), \
+}
+
+static AD7266_DECLARE_DIFF_CHANNELS(s, 's');
+static AD7266_DECLARE_DIFF_CHANNELS(u, 'u');
+
+#define AD7266_DECLARE_DIFF_CHANNELS_FIXED(_name, _sign) \
+const struct iio_chan_spec ad7266_channels_diff_fixed_##_name[] = { \
+	AD7266_CHAN_DIFF(0, (_sign)), \
+	AD7266_CHAN_DIFF(1, (_sign)), \
+	IIO_CHAN_SOFT_TIMESTAMP(2), \
+}
+
+static AD7266_DECLARE_DIFF_CHANNELS_FIXED(s, 's');
+static AD7266_DECLARE_DIFF_CHANNELS_FIXED(u, 'u');
+
+static const struct iio_info ad7266_info = {
+	.read_raw = &ad7266_read_raw,
+	.update_scan_mode = &ad7266_update_scan_mode,
+	.driver_module = THIS_MODULE,
+};
+
+static unsigned long ad7266_available_scan_masks[] = {
+	0x003,
+	0x00c,
+	0x030,
+	0x0c0,
+	0x300,
+	0xc00,
+	0x000,
+};
+
+static unsigned long ad7266_available_scan_masks_diff[] = {
+	0x003,
+	0x00c,
+	0x030,
+	0x000,
+};
+
+static unsigned long ad7266_available_scan_masks_fixed[] = {
+	0x003,
+	0x000,
+};
+
+struct ad7266_chan_info {
+	const struct iio_chan_spec *channels;
+	unsigned int num_channels;
+	unsigned long *scan_masks;
+};
+
+#define AD7266_CHAN_INFO_INDEX(_differential, _signed, _fixed) \
+	(((_differential) << 2) | ((_signed) << 1) | ((_fixed) << 0))
+
+static const struct ad7266_chan_info ad7266_chan_infos[] = {
+	[AD7266_CHAN_INFO_INDEX(0, 0, 0)] = {
+		.channels = ad7266_channels_u,
+		.num_channels = ARRAY_SIZE(ad7266_channels_u),
+		.scan_masks = ad7266_available_scan_masks,
+	},
+	[AD7266_CHAN_INFO_INDEX(0, 0, 1)] = {
+		.channels = ad7266_channels_u_fixed,
+		.num_channels = ARRAY_SIZE(ad7266_channels_u_fixed),
+		.scan_masks = ad7266_available_scan_masks_fixed,
+	},
+	[AD7266_CHAN_INFO_INDEX(0, 1, 0)] = {
+		.channels = ad7266_channels_s,
+		.num_channels = ARRAY_SIZE(ad7266_channels_s),
+		.scan_masks = ad7266_available_scan_masks,
+	},
+	[AD7266_CHAN_INFO_INDEX(0, 1, 1)] = {
+		.channels = ad7266_channels_s_fixed,
+		.num_channels = ARRAY_SIZE(ad7266_channels_s_fixed),
+		.scan_masks = ad7266_available_scan_masks_fixed,
+	},
+	[AD7266_CHAN_INFO_INDEX(1, 0, 0)] = {
+		.channels = ad7266_channels_diff_u,
+		.num_channels = ARRAY_SIZE(ad7266_channels_diff_u),
+		.scan_masks = ad7266_available_scan_masks_diff,
+	},
+	[AD7266_CHAN_INFO_INDEX(1, 0, 1)] = {
+		.channels = ad7266_channels_diff_fixed_u,
+		.num_channels = ARRAY_SIZE(ad7266_channels_diff_fixed_u),
+		.scan_masks = ad7266_available_scan_masks_fixed,
+	},
+	[AD7266_CHAN_INFO_INDEX(1, 1, 0)] = {
+		.channels = ad7266_channels_diff_s,
+		.num_channels = ARRAY_SIZE(ad7266_channels_diff_s),
+		.scan_masks = ad7266_available_scan_masks_diff,
+	},
+	[AD7266_CHAN_INFO_INDEX(1, 1, 1)] = {
+		.channels = ad7266_channels_diff_fixed_s,
+		.num_channels = ARRAY_SIZE(ad7266_channels_diff_fixed_s),
+		.scan_masks = ad7266_available_scan_masks_fixed,
+	},
+};
+
+static void __devinit ad7266_init_channels(struct iio_dev *indio_dev)
+{
+	struct ad7266_state *st = iio_priv(indio_dev);
+	bool is_differential, is_signed;
+	const struct ad7266_chan_info *chan_info;
+	int i;
+
+	is_differential = st->mode != AD7266_MODE_SINGLE_ENDED;
+	is_signed = (st->range == AD7266_RANGE_2VREF) |
+		    (st->mode == AD7266_MODE_DIFF);
+
+	i = AD7266_CHAN_INFO_INDEX(is_differential, is_signed, st->fixed_addr);
+	chan_info = &ad7266_chan_infos[i];
+
+	indio_dev->channels = chan_info->channels;
+	indio_dev->num_channels = chan_info->num_channels;
+	indio_dev->available_scan_masks = chan_info->scan_masks;
+	indio_dev->masklength = chan_info->num_channels - 1;
+}
+
+static const char * const ad7266_gpio_labels[] = {
+	"AD0", "AD1", "AD2",
+};
+
+static int __devinit ad7266_probe(struct spi_device *spi)
+{
+	struct ad7266_platform_data *pdata = spi->dev.platform_data;
+	struct iio_dev *indio_dev;
+	struct ad7266_state *st;
+	unsigned int i;
+	int ret;
+
+	indio_dev = iio_device_alloc(sizeof(*st));
+	if (indio_dev == NULL)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+
+	st->reg = regulator_get(&spi->dev, "vref");
+	if (!IS_ERR_OR_NULL(st->reg)) {
+		ret = regulator_enable(st->reg);
+		if (ret)
+			goto error_put_reg;
+
+		st->vref_uv = regulator_get_voltage(st->reg);
+	} else {
+		/* Use internal reference */
+		st->vref_uv = 2500000;
+	}
+
+	if (pdata) {
+		st->fixed_addr = pdata->fixed_addr;
+		st->mode = pdata->mode;
+		st->range = pdata->range;
+
+		if (!st->fixed_addr) {
+			for (i = 0; i < ARRAY_SIZE(st->gpios); ++i) {
+				st->gpios[i].gpio = pdata->addr_gpios[i];
+				st->gpios[i].flags = GPIOF_OUT_INIT_LOW;
+				st->gpios[i].label = ad7266_gpio_labels[i];
+			}
+			ret = gpio_request_array(st->gpios,
+				ARRAY_SIZE(st->gpios));
+			if (ret)
+				goto error_disable_reg;
+		}
+	} else {
+		st->fixed_addr = true;
+		st->range = AD7266_RANGE_VREF;
+		st->mode = AD7266_MODE_DIFF;
+	}
+
+	spi_set_drvdata(spi, indio_dev);
+	st->spi = spi;
+
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &ad7266_info;
+
+	ad7266_init_channels(indio_dev);
+
+	/* wakeup */
+	st->single_xfer[0].rx_buf = &st->data;
+	st->single_xfer[0].len = 2;
+	st->single_xfer[0].cs_change = 1;
+	/* conversion */
+	st->single_xfer[1].rx_buf = &st->data;
+	st->single_xfer[1].len = 4;
+	st->single_xfer[1].cs_change = 1;
+	/* powerdown */
+	st->single_xfer[2].tx_buf = &st->data;
+	st->single_xfer[2].len = 1;
+
+	spi_message_init(&st->single_msg);
+	spi_message_add_tail(&st->single_xfer[0], &st->single_msg);
+	spi_message_add_tail(&st->single_xfer[1], &st->single_msg);
+	spi_message_add_tail(&st->single_xfer[2], &st->single_msg);
+
+	ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
+		&ad7266_trigger_handler, &iio_triggered_buffer_setup_ops);
+	if (ret)
+		goto error_free_gpios;
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto error_buffer_cleanup;
+
+	return 0;
+
+error_buffer_cleanup:
+	iio_triggered_buffer_cleanup(indio_dev);
+error_free_gpios:
+	if (!st->fixed_addr)
+		gpio_free_array(st->gpios, ARRAY_SIZE(st->gpios));
+error_disable_reg:
+	if (!IS_ERR_OR_NULL(st->reg))
+		regulator_disable(st->reg);
+error_put_reg:
+	if (!IS_ERR_OR_NULL(st->reg))
+		regulator_put(st->reg);
+
+	iio_device_free(indio_dev);
+
+	return ret;
+}
+
+static int __devexit ad7266_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct ad7266_state *st = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+	if (!st->fixed_addr)
+		gpio_free_array(st->gpios, ARRAY_SIZE(st->gpios));
+	if (!IS_ERR_OR_NULL(st->reg)) {
+		regulator_disable(st->reg);
+		regulator_put(st->reg);
+	}
+	iio_device_free(indio_dev);
+
+	return 0;
+}
+
+static const struct spi_device_id ad7266_id[] = {
+	{"ad7265", 0},
+	{"ad7266", 0},
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ad7266_id);
+
+static struct spi_driver ad7266_driver = {
+	.driver = {
+		.name	= "ad7266",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= ad7266_probe,
+	.remove		= __devexit_p(ad7266_remove),
+	.id_table	= ad7266_id,
+};
+module_spi_driver(ad7266_driver);
+
+MODULE_AUTHOR("Lars-Peter Clausen <[e-mail]>");
+MODULE_DESCRIPTION("Analog Devices AD7266/65 ADC");
+MODULE_LICENSE("GPL v2");

include/linux/platform_data/ad7266.h

···
+/*
+ * AD7266/65 SPI ADC driver
+ *
+ * Copyright 2012 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2.
+ */
+
+#ifndef __IIO_ADC_AD7266_H__
+#define __IIO_ADC_AD7266_H__
+
+/**
+ * enum ad7266_range - AD7266 reference voltage range
+ * @AD7266_RANGE_VREF: Device is configured for input range 0V - VREF
+ *			(RANGE pin set to low)
+ * @AD7266_RANGE_2VREF: Device is configured for input range 0V - 2VREF
+ *			(RANGE pin set to high)
+ */
+enum ad7266_range {
+	AD7266_RANGE_VREF,
+	AD7266_RANGE_2VREF,
+};
+
+/**
+ * enum ad7266_mode - AD7266 sample mode
+ * @AD7266_MODE_DIFF: Device is configured for full differential mode
+ *				(SGL/DIFF pin set to low, AD0 pin set to low)
+ * @AD7266_MODE_PSEUDO_DIFF: Device is configured for pseudo differential mode
+ *				(SGL/DIFF pin set to low, AD0 pin set to high)
+ * @AD7266_MODE_SINGLE_ENDED: Device is configured for single-ended mode
+ *				(SGL/DIFF pin set to high)
+ */
+enum ad7266_mode {
+	AD7266_MODE_DIFF,
+	AD7266_MODE_PSEUDO_DIFF,
+	AD7266_MODE_SINGLE_ENDED,
+};
+
+/**
+ * struct ad7266_platform_data - Platform data for the AD7266 driver
+ * @range: Reference voltage range the device is configured for
+ * @mode: Sample mode the device is configured for
+ * @fixed_addr: Whether the address pins are hard-wired
+ * @addr_gpios: GPIOs used for controlling the address pins, only used if
+ *		fixed_addr is set to false.
+ */
+struct ad7266_platform_data {
+	enum ad7266_range range;
+	enum ad7266_mode mode;
+	bool fixed_addr;
+	unsigned int addr_gpios[3];
+};
+
+#endif