[PATCH] iio: adc: New driver for TI ADS79XX chips

[David Lechner]

This adds a new driver for TI ADS79XX ADC chips. These communicate using
SPI and come in 8/10/12-bit and 4/8/12/16 channel varieties.

Signed-off-by: David Lechner <david@xxxxxxxxxxxxxx>
---
 drivers/iio/adc/Kconfig      |  13 ++
 drivers/iio/adc/Makefile     |   1 +
 drivers/iio/adc/ti-ads79xx.c | 492 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 506 insertions(+)
 create mode 100644 drivers/iio/adc/ti-ads79xx.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 99c0514..e87e8a5 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -503,6 +503,19 @@ config TI_ADS1015
 	  This driver can also be built as a module. If so, the module will be
 	  called ti-ads1015.
 
+config TI_ADS79XX
+	tristate "Texas Instruments ADS79XX ADC driver"
+	depends on SPI
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for Texas Instruments ADS7950, ADS7951,
+	  ADS7952, ADS7953, ADS7954, ADS7955, ADS7956, ADS7957, ADS7958, ADS7959.
+	  ADS7960, ADS7961.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ti-ads79xx.
+
 config TI_ADS8688
 	tristate "Texas Instruments ADS8688"
 	depends on SPI && OF
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 7a40c04..8d0659a 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -47,6 +47,7 @@ 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
+obj-$(CONFIG_TI_ADS79XX) += ti-ads79xx.o
 obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
 obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
 obj-$(CONFIG_TWL4030_MADC) += twl4030-madc.o
diff --git a/drivers/iio/adc/ti-ads79xx.c b/drivers/iio/adc/ti-ads79xx.c
new file mode 100644
index 0000000..42cade0
--- /dev/null
+++ b/drivers/iio/adc/ti-ads79xx.c
@@ -0,0 +1,492 @@
+/*
+ * Texas Instruments ADS79XX SPI ADC driver
+ *
+ * Copyright 2016 David Lechner <david@xxxxxxxxxxxxxx>
+ *
+ * Based on iio/ad7923.c:
+ * Copyright 2011 Analog Devices Inc
+ * Copyright 2012 CS Systemes d'Information
+ *
+ * And also on hwmon/ads79xx.c
+ * Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com/
+ *	Nishanth Menon
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/spi/spi.h>
+#include <linux/regulator/consumer.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+#define ADS79XX_CR_MANUAL	(1 << 12)
+#define ADS79XX_CR_WRITE	(1 << 11)
+#define ADS79XX_CR_CHAN(ch)	(ch << 7)
+#define ADS79XX_CR_RANGE_5V	(1 << 6)
+
+#define ADS79XX_MAX_CHAN	16
+
+/* val = value, dec = left shift, bits = number of bits of the mask */
+#define EXTRACT(val, dec, bits)		((val >> dec) & ((1 << bits) - 1))
+
+struct ti_ads79xx_state {
+	struct spi_device	*spi;
+	struct spi_transfer	ring_xfer[ADS79XX_MAX_CHAN+2];
+	struct spi_transfer	scan_single_xfer[3];
+	struct spi_message	ring_msg;
+	struct spi_message	scan_single_msg;
+
+	struct regulator	*reg;
+
+	unsigned int		settings;
+
+	/*
+	 * DMA (thus cache coherency maintenance) requires the
+	 * transfer buffers to live in their own cache lines.
+	 */
+	__be16			rx_buf[ADS79XX_MAX_CHAN] ____cacheline_aligned;
+	__be16			tx_buf[ADS79XX_MAX_CHAN];
+};
+
+struct ti_ads79xx_chip_info {
+	const struct iio_chan_spec *channels;
+	unsigned int num_channels;
+};
+
+enum ti_ads79xx_id {
+	ADS7950,
+	ADS7951,
+	ADS7952,
+	ADS7953,
+	ADS7954,
+	ADS7955,
+	ADS7956,
+	ADS7957,
+	ADS7958,
+	ADS7959,
+	ADS7960,
+	ADS7961,
+};
+
+#define ADS79XX_V_CHAN(index, bits)				\
+{								\
+	.type = IIO_VOLTAGE,					\
+	.indexed = 1,						\
+	.channel = index,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+	.address = index,					\
+	.datasheet_name = "CH##index",				\
+	.scan_index = index,					\
+	.scan_type = {						\
+		.sign = 'u',					\
+		.realbits = (bits),				\
+		.storagebits = 16,				\
+		.endianness = IIO_BE,				\
+	},							\
+}
+
+#define DECLARE_ADS79XX_4_CHANNELS(name, bits) \
+const struct iio_chan_spec name ## _channels[] = { \
+	ADS79XX_V_CHAN(0, bits), \
+	ADS79XX_V_CHAN(1, bits), \
+	ADS79XX_V_CHAN(2, bits), \
+	ADS79XX_V_CHAN(3, bits), \
+	IIO_CHAN_SOFT_TIMESTAMP(4), \
+}
+
+#define DECLARE_ADS79XX_8_CHANNELS(name, bits) \
+const struct iio_chan_spec name ## _channels[] = { \
+	ADS79XX_V_CHAN(0, bits), \
+	ADS79XX_V_CHAN(1, bits), \
+	ADS79XX_V_CHAN(2, bits), \
+	ADS79XX_V_CHAN(3, bits), \
+	ADS79XX_V_CHAN(4, bits), \
+	ADS79XX_V_CHAN(5, bits), \
+	ADS79XX_V_CHAN(6, bits), \
+	ADS79XX_V_CHAN(7, bits), \
+	IIO_CHAN_SOFT_TIMESTAMP(8), \
+}
+
+#define DECLARE_ADS79XX_12_CHANNELS(name, bits) \
+const struct iio_chan_spec name ## _channels[] = { \
+	ADS79XX_V_CHAN(0, bits), \
+	ADS79XX_V_CHAN(1, bits), \
+	ADS79XX_V_CHAN(2, bits), \
+	ADS79XX_V_CHAN(3, bits), \
+	ADS79XX_V_CHAN(4, bits), \
+	ADS79XX_V_CHAN(5, bits), \
+	ADS79XX_V_CHAN(6, bits), \
+	ADS79XX_V_CHAN(7, bits), \
+	ADS79XX_V_CHAN(8, bits), \
+	ADS79XX_V_CHAN(9, bits), \
+	ADS79XX_V_CHAN(10, bits), \
+	ADS79XX_V_CHAN(11, bits), \
+	IIO_CHAN_SOFT_TIMESTAMP(12), \
+}
+
+#define DECLARE_ADS79XX_16_CHANNELS(name, bits) \
+const struct iio_chan_spec name ## _channels[] = { \
+	ADS79XX_V_CHAN(0, bits), \
+	ADS79XX_V_CHAN(1, bits), \
+	ADS79XX_V_CHAN(2, bits), \
+	ADS79XX_V_CHAN(3, bits), \
+	ADS79XX_V_CHAN(4, bits), \
+	ADS79XX_V_CHAN(5, bits), \
+	ADS79XX_V_CHAN(6, bits), \
+	ADS79XX_V_CHAN(7, bits), \
+	ADS79XX_V_CHAN(8, bits), \
+	ADS79XX_V_CHAN(9, bits), \
+	ADS79XX_V_CHAN(10, bits), \
+	ADS79XX_V_CHAN(11, bits), \
+	ADS79XX_V_CHAN(12, bits), \
+	ADS79XX_V_CHAN(13, bits), \
+	ADS79XX_V_CHAN(14, bits), \
+	ADS79XX_V_CHAN(15, bits), \
+	IIO_CHAN_SOFT_TIMESTAMP(16), \
+}
+
+static DECLARE_ADS79XX_4_CHANNELS(ti_ads7950, 12);
+static DECLARE_ADS79XX_8_CHANNELS(ti_ads7951, 12);
+static DECLARE_ADS79XX_12_CHANNELS(ti_ads7952, 12);
+static DECLARE_ADS79XX_16_CHANNELS(ti_ads7953, 12);
+static DECLARE_ADS79XX_4_CHANNELS(ti_ads7954, 10);
+static DECLARE_ADS79XX_8_CHANNELS(ti_ads7955, 10);
+static DECLARE_ADS79XX_12_CHANNELS(ti_ads7956, 10);
+static DECLARE_ADS79XX_16_CHANNELS(ti_ads7957, 10);
+static DECLARE_ADS79XX_4_CHANNELS(ti_ads7958, 8);
+static DECLARE_ADS79XX_8_CHANNELS(ti_ads7959, 8);
+static DECLARE_ADS79XX_12_CHANNELS(ti_ads7960, 8);
+static DECLARE_ADS79XX_16_CHANNELS(ti_ads7961, 8);
+
+static const struct ti_ads79xx_chip_info ti_ads79xx_chip_info[] = {
+	[ADS7950] = {
+		.channels	= ti_ads7950_channels,
+		.num_channels	= ARRAY_SIZE(ti_ads7950_channels),
+	},
+	[ADS7951] = {
+		.channels	= ti_ads7951_channels,
+		.num_channels	= ARRAY_SIZE(ti_ads7951_channels),
+	},
+	[ADS7952] = {
+		.channels	= ti_ads7952_channels,
+		.num_channels	= ARRAY_SIZE(ti_ads7952_channels),
+	},
+	[ADS7953] = {
+		.channels	= ti_ads7953_channels,
+		.num_channels	= ARRAY_SIZE(ti_ads7953_channels),
+	},
+	[ADS7954] = {
+		.channels	= ti_ads7954_channels,
+		.num_channels	= ARRAY_SIZE(ti_ads7954_channels),
+	},
+	[ADS7955] = {
+		.channels	= ti_ads7955_channels,
+		.num_channels	= ARRAY_SIZE(ti_ads7955_channels),
+	},
+	[ADS7956] = {
+		.channels	= ti_ads7956_channels,
+		.num_channels	= ARRAY_SIZE(ti_ads7956_channels),
+	},
+	[ADS7957] = {
+		.channels	= ti_ads7957_channels,
+		.num_channels	= ARRAY_SIZE(ti_ads7957_channels),
+	},
+	[ADS7958] = {
+		.channels	= ti_ads7958_channels,
+		.num_channels	= ARRAY_SIZE(ti_ads7958_channels),
+	},
+	[ADS7959] = {
+		.channels	= ti_ads7959_channels,
+		.num_channels	= ARRAY_SIZE(ti_ads7959_channels),
+	},
+	[ADS7960] = {
+		.channels	= ti_ads7960_channels,
+		.num_channels	= ARRAY_SIZE(ti_ads7960_channels),
+	},
+	[ADS7961] = {
+		.channels	= ti_ads7961_channels,
+		.num_channels	= ARRAY_SIZE(ti_ads7961_channels),
+	},
+};
+
+/*
+ * ti_ads79xx_update_scan_mode() setup the spi transfer buffer for the new
+ * scan mask
+ */
+static int ti_ads79xx_update_scan_mode(struct iio_dev *indio_dev,
+				       const unsigned long *active_scan_mask)
+{
+	struct ti_ads79xx_state *st = iio_priv(indio_dev);
+	int i, cmd, len;
+
+	len = 0;
+	for_each_set_bit(i, active_scan_mask, indio_dev->num_channels) {
+		cmd = ADS79XX_CR_WRITE | ADS79XX_CR_CHAN(i) | st->settings;
+		st->tx_buf[len++] = cpu_to_be16(cmd);
+	}
+
+	/* build spi ring message */
+	spi_message_init(&st->ring_msg);
+
+	/* Data for the 1st channel is not retuned until the 3rd transfer */
+	len += 2;
+	for (i = 0; i < len; i++) {
+		if ((i + 2) < len)
+			st->ring_xfer[i].tx_buf = &st->tx_buf[i];
+		if (i >= 2)
+			st->ring_xfer[i].rx_buf = &st->rx_buf[i - 2];
+		st->ring_xfer[i].len = 2;
+		st->ring_xfer[i].cs_change = 1;
+		spi_message_add_tail(&st->ring_xfer[i], &st->ring_msg);
+	}
+	/* make sure last transfer's cs_change is not set */
+	st->ring_xfer[len - 1].cs_change = 0;
+
+	return 0;
+}
+
+/*
+ * ti_ads79xx_trigger_handler() bh of trigger launched polling to ring buffer
+ *
+ * Currently there is no option in this driver to disable the saving of
+ * timestamps within the ring.
+ */
+static irqreturn_t ti_ads79xx_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct ti_ads79xx_state *st = iio_priv(indio_dev);
+	int b_sent;
+
+	b_sent = spi_sync(st->spi, &st->ring_msg);
+	if (b_sent)
+		goto done;
+
+	iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
+					   iio_get_time_ns(indio_dev));
+
+done:
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static int ti_ads79xx_scan_direct(struct ti_ads79xx_state *st, unsigned ch)
+{
+	int ret, cmd;
+
+	cmd = ADS79XX_CR_WRITE | ADS79XX_CR_CHAN(ch) | st->settings;
+	st->tx_buf[0] = cpu_to_be16(cmd);
+
+	ret = spi_sync(st->spi, &st->scan_single_msg);
+	if (ret)
+		return ret;
+
+	return be16_to_cpu(st->rx_buf[0]);
+}
+
+static int ti_ads79xx_get_range(struct ti_ads79xx_state *st)
+{
+	int vref;
+
+	vref = regulator_get_voltage(st->reg);
+	if (vref < 0)
+		return vref;
+
+	vref /= 1000;
+
+	if (st->settings & ADS79XX_CR_RANGE_5V)
+		vref *= 2;
+
+	return vref;
+}
+
+static int ti_ads79xx_read_raw(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan,
+			       int *val, int *val2, long m)
+{
+	struct ti_ads79xx_state *st = iio_priv(indio_dev);
+	int ret;
+
+	switch (m) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&indio_dev->mlock);
+		if (iio_buffer_enabled(indio_dev))
+			ret = -EBUSY;
+		else
+			ret = ti_ads79xx_scan_direct(st, chan->address);
+		mutex_unlock(&indio_dev->mlock);
+
+		if (ret < 0)
+			return ret;
+
+		if (chan->address == EXTRACT(ret, 12, 4))
+			*val = EXTRACT(ret, 0, 12);
+		else
+			return -EIO;
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		ret = ti_ads79xx_get_range(st);
+		if (ret < 0)
+			return ret;
+		*val = ret;
+		*val2 = chan->scan_type.realbits;
+		return IIO_VAL_FRACTIONAL_LOG2;
+	}
+	return -EINVAL;
+}
+
+static const struct iio_info ti_ads79xx_info = {
+	.read_raw		= &ti_ads79xx_read_raw,
+	.update_scan_mode	= ti_ads79xx_update_scan_mode,
+	.driver_module		= THIS_MODULE,
+};
+
+static int ti_ads79xx_probe(struct spi_device *spi)
+{
+	struct ti_ads79xx_state *st;
+	struct iio_dev *indio_dev;
+	const struct ti_ads79xx_chip_info *info;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (indio_dev == NULL)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+
+	spi_set_drvdata(spi, indio_dev);
+
+	st->spi = spi;
+	st->settings = ADS79XX_CR_MANUAL | ADS79XX_CR_RANGE_5V;
+
+	info = &ti_ads79xx_chip_info[spi_get_device_id(spi)->driver_data];
+
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = info->channels;
+	indio_dev->num_channels = info->num_channels;
+	indio_dev->info = &ti_ads79xx_info;
+
+	/*
+	 * Setup default message. The chip takes one full cycle to convert a
+	 * sample. The conversion process is driven by the SPI clock, which
+	 * is why we have 3 transfers. The middle one is just dummy data sent
+	 * while the chip is converting the sample from first transfer.
+	 */
+
+	st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
+	st->scan_single_xfer[0].len = 2;
+	st->scan_single_xfer[0].cs_change = 1;
+	st->scan_single_xfer[1].tx_buf = &st->tx_buf[0];
+	st->scan_single_xfer[1].len = 2;
+	st->scan_single_xfer[1].cs_change = 1;
+	st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
+	st->scan_single_xfer[2].len = 2;
+
+	spi_message_init(&st->scan_single_msg);
+	spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
+	spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
+	spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);
+
+	st->reg = devm_regulator_get(&spi->dev, "refin");
+	if (IS_ERR(st->reg)) {
+		dev_err(&spi->dev, "Failed get get regulator \"refin\"\n");
+		return PTR_ERR(st->reg);
+	}
+
+	ret = regulator_enable(st->reg);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to enable regulator \"refin\"\n");
+		return ret;
+	}
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+					 &ti_ads79xx_trigger_handler, NULL);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to setup triggered buffer\n");
+		goto error_disable_reg;
+	}
+
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to register iio device\n");
+		goto error_cleanup_ring;
+	}
+
+	dev_info(&spi->dev, "Registered %s\n", indio_dev->name);
+
+	return 0;
+
+error_cleanup_ring:
+	iio_triggered_buffer_cleanup(indio_dev);
+error_disable_reg:
+	regulator_disable(st->reg);
+
+	return ret;
+}
+
+static int ti_ads79xx_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct ti_ads79xx_state *st = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+	regulator_disable(st->reg);
+
+	return 0;
+}
+
+static const struct spi_device_id ti_ads79xx_id[] = {
+	{"ti-ads7950", ADS7950},
+	{"ti-ads7951", ADS7951},
+	{"ti-ads7952", ADS7952},
+	{"ti-ads7953", ADS7953},
+	{"ti-ads7954", ADS7954},
+	{"ti-ads7955", ADS7955},
+	{"ti-ads7956", ADS7956},
+	{"ti-ads7957", ADS7957},
+	{"ti-ads7958", ADS7958},
+	{"ti-ads7959", ADS7959},
+	{"ti-ads7960", ADS7960},
+	{"ti-ads7961", ADS7961},
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ti_ads79xx_id);
+
+static struct spi_driver ti_ads79xx_driver = {
+	.driver = {
+		.name	= "ti-ads79xx",
+	},
+	.probe		= ti_ads79xx_probe,
+	.remove		= ti_ads79xx_remove,
+	.id_table	= ti_ads79xx_id,
+};
+module_spi_driver(ti_ads79xx_driver);
+
+MODULE_AUTHOR("David Lechner <david@xxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("TI ADS79XX ADC");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4