Message-Id: <20211108184359.439537-1-drhunter95@gmail.com>
Date:   Mon,  8 Nov 2021 18:43:43 +0000
From:   Iain Hunter <drhunter95@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     iain@...terembedded.co.uk, Iain Hunter <drhunter95@...il.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Alexandru Ardelean <aardelean@...iqon.com>,
        Biju Das <biju.das.jz@...renesas.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Oleksij Rempel <linux@...pel-privat.de>,
        Tomislav Denis <tomislav.denis@....com>,
        Cai Huoqing <caihuoqing@...du.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Fabio Estevam <festevam@...il.com>,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org
Subject: [PATCH 2/2] add IIO support for TI ADS1018 SPI ADC

Add a new IIO ADC driver for ADS1018 from TI.
It is a 12bit SPI device similar to I2C ADS1015. 

Signed-off-by: Iain Hunter <drhunter95@...il.com>
---
 drivers/iio/adc/Kconfig      |  12 +
 drivers/iio/adc/Makefile     |   1 +
 drivers/iio/adc/ti-ads1018.c | 834 +++++++++++++++++++++++++++++++++++
 3 files changed, 847 insertions(+)
 create mode 100644 drivers/iio/adc/ti-ads1018.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 8bf5b62a73f4..129194755c03 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1131,6 +1131,18 @@ config TI_ADS1015
 	  This driver can also be built as a module. If so, the module will be
 	  called ti-ads1015.
 
+config TI_ADS1018
+	tristate "Texas Instruments ADS1018 ADC"
+	depends on SPI
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  If you say yes here you get support for Texas Instruments ADS1018
+	  ADC chip.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ti-ads1018.
+
 config TI_ADS7950
 	tristate "Texas Instruments ADS7950 ADC driver"
 	depends on SPI && GPIOLIB
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index d3f53549720c..da462538ec17 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -101,6 +101,7 @@ obj-$(CONFIG_TI_ADC108S102) += ti-adc108s102.o
 obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
 obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
 obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
+obj-$(CONFIG_TI_ADS1018) += ti-ads1018.o
 obj-$(CONFIG_TI_ADS7950) += ti-ads7950.o
 obj-$(CONFIG_TI_ADS8344) += ti-ads8344.o
 obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
diff --git a/drivers/iio/adc/ti-ads1018.c b/drivers/iio/adc/ti-ads1018.c
new file mode 100644
index 000000000000..5f997f523240
--- /dev/null
+++ b/drivers/iio/adc/ti-ads1018.c
@@ -0,0 +1,834 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADS1018 - Texas Instruments Analog-to-Digital Converter
+ *
+ * Copyright 2021 Iain Hunter <iain@...terembedded.co.uk>
+ *
+ * Based on ti-ads1015.c
+ * Copyright (c) 2016, Intel Corporation.
+ *
+ * IIO driver for 12 bit SPI ADC ADS1018 from TI
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/init.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+#include <linux/pm_runtime.h>
+#include <linux/mutex.h>
+#include <linux/delay.h>
+
+
+#include <linux/iio/iio.h>
+#include <linux/iio/types.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/events.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
+
+
+#define ADS1018_DRV_NAME "ads1018"
+
+#define TI_ADS1018_START_SINGLE_SHOT            BIT(15)
+
+#define TI_ADS1018_MUX_AIN0_SINGLE_ENDED	BIT(14)
+#define TI_ADS1018_MUX_AIN1_SINGLE_ENDED	(BIT(14) | BIT(12))
+
+#define TI_ADS1018_MUX_MASK			0x7
+#define TI_ADS1018_MUX_SHIFT			12
+
+#define TI_ADS1018_PGA_2_048V			BIT(10)
+
+#define TI_ADS1018_PGA_MASK			0x7
+#define TI_ADS1018_PGA_SHIFT			9
+
+#define TI_ADS1018_MODE_SINGLE_SHOT		BIT(8)
+#define TI_ADS1018_MODE_CONTINUOUS		0x0
+
+#define TI_ADS1018_MODE_MASK			0x1
+#define TI_ADS1018_MODE_SHIFT			8
+
+#define TI_ADS1018_STATE_RATE_1600		BIT(7)
+#define TI_ADS1018_STATE_RATE_2400		(BIT(7) | BIT(5))
+#define TI_ADS1018_STATE_RATE_3300		(BIT(7) | BIT(6))
+
+#define TI_ADS1018_DR_MASK			0x7
+#define TI_ADS1018_DR_SHIFT			5
+
+#define TI_ADS1018_TS_MODE_ADC			0x0
+#define TI_ADS1018_TS_MODE_TEMP			BIT(4)
+
+#define TI_ADS1018_PULLUP_DOUT_DISABLE		0x0
+#define TI_ADS1018_PULLUP_DOUT_ENABLE		BIT(3)
+
+#define TI_ADS1018_NOP_UPDATE_CONFIG		BIT(1)
+#define TI_ADS1018_RESERVED			BIT(0)
+
+#define TI_ADS1018_CONFIGURE    (TI_ADS1018_PGA_2_048V | \
+				TI_ADS1018_MODE_CONTINUOUS | \
+				TI_ADS1018_STATE_RATE_2400 | \
+				TI_ADS1018_TS_MODE_ADC | \
+				TI_ADS1018_PULLUP_DOUT_ENABLE | \
+				TI_ADS1018_NOP_UPDATE_CONFIG | \
+				TI_ADS1018_RESERVED)
+
+
+#define ADS1018_CHANNELS                        8
+
+#define TI_ADS1018_TIMESTAMP_SIZE (sizeof(int64_t) / sizeof(__be16))
+
+/* val = value, dec = left shift, bits = number of bits of the mask */
+#define TI_ADS1018_EXTRACT(val, dec, bits) \
+	(((val) >> (dec)) & ((1 << (bits)) - 1))
+
+
+
+#define ADS1018_SLEEP_DELAY_MS			2000
+#define ADS1018_DEFAULT_PGA			2
+#define ADS1018_DEFAULT_DATA_RATE		4
+#define ADS1018_DEFAULT_CHAN			0
+
+
+struct ads1018_channel_data {
+	bool enabled;
+	unsigned int pga;
+	unsigned int data_rate;
+};
+
+
+enum chip_ids {
+	TI_ADS1018,
+	TI_ADS1118,
+};
+
+enum ads1018_channels {
+	ADS1018_AIN0_AIN1 = 0,
+	ADS1018_AIN0_AIN3,
+	ADS1018_AIN1_AIN3,
+	ADS1018_AIN2_AIN3,
+	ADS1018_AIN0,
+	ADS1018_AIN1,
+	ADS1018_AIN2,
+	ADS1018_AIN3,
+	ADS1018_TIMESTAMP,
+};
+
+struct ti_ads1018_chip_info {
+	const struct iio_chan_spec *channels;
+	unsigned int num_channels;
+};
+
+static const unsigned int ads1018_data_rate[] = {
+	128, 250, 490, 920, 1600, 2400, 3300, 3300
+};
+
+/*
+ * Translation from PGA bits to full-scale positive and negative input voltage
+ * range in mV
+ */
+static int ads1018_fullscale_range[] = {
+	6144, 4096, 2048, 1024, 512, 256, 256, 256
+};
+
+
+#define ADS1018_V_CHAN(_chan, _addr) {				\
+	.type = IIO_VOLTAGE,					\
+	.indexed = 1,						\
+	.address = _addr,					\
+	.channel = _chan,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
+				BIT(IIO_CHAN_INFO_SCALE) |	\
+				BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.scan_index = _addr,					\
+	.scan_type = {						\
+		.sign = 's',					\
+		.realbits = 12,					\
+		.storagebits = 16,				\
+		.shift = 4,					\
+		.endianness = IIO_CPU,				\
+	},							\
+	.datasheet_name = "AIN"#_chan,				\
+}
+
+#define ADS1018_V_DIFF_CHAN(_chan, _chan2, _addr) {		\
+	.type = IIO_VOLTAGE,					\
+	.differential = 1,					\
+	.indexed = 1,						\
+	.address = _addr,					\
+	.channel = _chan,					\
+	.channel2 = _chan2,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
+				BIT(IIO_CHAN_INFO_SCALE) |	\
+				BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.scan_index = _addr,					\
+	.scan_type = {						\
+		.sign = 's',					\
+		.realbits = 12,					\
+		.storagebits = 16,				\
+		.shift = 4,					\
+		.endianness = IIO_CPU,				\
+	},							\
+	.datasheet_name = "AIN"#_chan"-AIN"#_chan2,		\
+}
+
+
+struct ti_ads1018_state {
+	struct spi_device	*spi;
+	struct spi_transfer	scan_single_xfer[1];
+	struct spi_message	scan_single_msg;
+
+	struct iio_trigger      *trig;
+	/*
+	 * Protects ADC ops, e.g: concurrent sysfs/buffered
+	 * data reads, configuration updates
+	 */
+	struct mutex                   lock;
+	struct ads1018_channel_data    channel_data[ADS1018_CHANNELS];
+	unsigned int                   current_config;
+	unsigned int                   settings;
+	unsigned int                   *data_rate;
+	/*
+	 * Set to true when the ADC is switched to the continuous-conversion
+	 * mode and exits from a power-down state.  This flag is used to avoid
+	 * getting the stale result from the conversion register.
+	 */
+	bool	conv_invalid;
+
+	/*
+	 * DMA (thus cache coherency maintenance) requires the
+	 * transfer buffers to live in their own cache lines.
+	 */
+	unsigned char	rx_buf[(ADS1018_CHANNELS + TI_ADS1018_TIMESTAMP_SIZE)*2]
+				____cacheline_aligned;
+	unsigned char	tx_buf[ADS1018_CHANNELS*2];
+
+};
+
+
+
+static const struct iio_chan_spec ti_ads1018_channels[] = {
+	ADS1018_V_DIFF_CHAN(0, 1, ADS1018_AIN0_AIN1),
+	ADS1018_V_DIFF_CHAN(0, 3, ADS1018_AIN0_AIN3),
+	ADS1018_V_DIFF_CHAN(1, 3, ADS1018_AIN1_AIN3),
+	ADS1018_V_DIFF_CHAN(2, 3, ADS1018_AIN2_AIN3),
+	ADS1018_V_CHAN(0, ADS1018_AIN0),
+	ADS1018_V_CHAN(1, ADS1018_AIN1),
+	ADS1018_V_CHAN(2, ADS1018_AIN2),
+	ADS1018_V_CHAN(3, ADS1018_AIN3),
+	IIO_CHAN_SOFT_TIMESTAMP(ADS1018_TIMESTAMP),
+};
+
+static const struct ti_ads1018_chip_info ti_ads1018_chip_info[] = {
+	[TI_ADS1018] = {
+		.channels	= ti_ads1018_channels,
+		.num_channels	= ARRAY_SIZE(ti_ads1018_channels),
+	},
+};
+
+
+static int ti_ads1018_write_config_register(struct ti_ads1018_state *st, int value)
+{
+	int ret;
+
+	/* Write new value to the first 2 bytes of the 4 byte SPI transfer	*/
+	st->tx_buf[0] = (value & 0xFF00)>>8;
+	st->tx_buf[1] = value & 0xFF;
+	st->tx_buf[2] = 0x00;
+	st->tx_buf[3] = 0x00;
+
+	ret = spi_sync(st->spi, &st->scan_single_msg);
+	if (ret)
+		return ret;
+
+	/* Update the state current config based on result of this write */
+	/* the updated config register value is in second 16 bit word    */
+	/* which is third and fourth byte                                */
+	st->current_config = (st->rx_buf[2] << 8);
+	st->current_config |= st->rx_buf[3];
+
+	return 0;
+}
+
+
+#ifdef CONFIG_PM
+static int ads1018_set_power_state(struct ti_ads1018_state *st, bool on)
+{
+	int ret;
+	struct spi_device *spi = st->spi;
+	struct device *dev = &(spi->dev);
+
+	if (on) {
+		ret = pm_runtime_get_sync(dev);
+		if (ret < 0)
+			pm_runtime_put_noidle(dev);
+	} else {
+		pm_runtime_mark_last_busy(dev);
+		ret = pm_runtime_put_autosuspend(dev);
+	}
+
+	return ret < 0 ? ret : 0;
+}
+#else /* !CONFIG_PM */
+static int ads1018_set_power_state(struct ti_ads1018_state *st, bool on)
+{
+	return 0;
+}
+#endif /* !CONFIG_PM */
+
+static
+int ads1018_get_adc_result(struct ti_ads1018_state *st, int chan, int *val)
+{
+	int ret, pga, dr, conv_time;
+	unsigned int old, mask, cfg;
+	unsigned int cmd;
+
+	if (chan < 0 || chan >= ADS1018_CHANNELS)
+		return -EINVAL;
+
+
+	old = st->current_config;
+
+	/* For just a data read cmd is 0x0000
+	 * Assumption is that previously the configuration has been set to
+	 * select channel, gain and sampling frequency
+	 */
+	cmd = 0x0000;
+
+	st->tx_buf[0] = (cmd & 0xFF00)>>8;
+	st->tx_buf[1] = cmd & 0xFF;
+	st->tx_buf[2] = 0x00;
+	st->tx_buf[3] = 0x00;
+	ret = spi_sync(st->spi, &st->scan_single_msg);
+
+	if (ret)
+		return ret;
+
+	*val = (st->rx_buf[0] << 8);
+	*val |= st->rx_buf[1];
+
+	pga = st->channel_data[chan].pga;
+	dr = st->channel_data[chan].data_rate;
+	mask =  (TI_ADS1018_MUX_MASK << TI_ADS1018_MUX_SHIFT) |
+		(TI_ADS1018_PGA_MASK << TI_ADS1018_PGA_SHIFT) |
+		(TI_ADS1018_DR_MASK << TI_ADS1018_DR_SHIFT);
+
+	cfg = chan << TI_ADS1018_MUX_SHIFT | pga << TI_ADS1018_PGA_SHIFT |
+		dr << TI_ADS1018_DR_SHIFT;
+
+	cfg = (old & ~mask) | (cfg & mask);
+
+
+	if (old != cfg || st->conv_invalid) {
+		int dr_old;
+
+		/* Update the configuration to the new one  */
+		ret = ti_ads1018_write_config_register(st, cfg);
+		if (ret)
+			return ret;
+
+		dr_old = (old & TI_ADS1018_DR_MASK) >>
+				TI_ADS1018_DR_SHIFT;
+
+		conv_time = DIV_ROUND_UP(USEC_PER_SEC, st->data_rate[dr_old]);
+		conv_time += DIV_ROUND_UP(USEC_PER_SEC, st->data_rate[dr]);
+		conv_time += conv_time / 10; /* 10% internal clock inaccuracy */
+		usleep_range(conv_time, conv_time + 1);
+		st->conv_invalid = false;
+	}
+
+	return 0;
+
+}
+
+static irqreturn_t ti_ads1018_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct ti_ads1018_state *st = iio_priv(indio_dev);
+	/* Ensure natural alignment of timestamp */
+	struct {
+		s16 chan;
+		s64 timestamp __aligned(8);
+
+	} scan;
+
+	int chan, ret, res;
+
+	memset(&scan, 0, sizeof(scan));
+
+	mutex_lock(&st->lock);
+	chan = find_first_bit(indio_dev->active_scan_mask,
+			      indio_dev->masklength);
+	ret = ads1018_get_adc_result(st, chan, &res);
+	if (ret < 0) {
+		mutex_unlock(&st->lock);
+		goto err;
+	}
+
+	scan.chan = res;
+	mutex_unlock(&st->lock);
+
+	iio_push_to_buffers_with_timestamp(indio_dev, &scan,
+					   iio_get_time_ns(indio_dev));
+
+err:
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static int ads1018_set_scale(struct ti_ads1018_state *st,
+			     struct iio_chan_spec const *chan,
+			     int scale, int uscale)
+{
+	int i;
+	int fullscale = div_s64((scale * 1000000LL + uscale) <<
+				(chan->scan_type.realbits - 1), 1000000);
+
+	for (i = 0; i < ARRAY_SIZE(ads1018_fullscale_range); i++) {
+		if (ads1018_fullscale_range[i] == fullscale) {
+			st->channel_data[chan->address].pga = i;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int ads1018_set_data_rate(struct ti_ads1018_state *st, int chan, int rate)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(ads1018_data_rate); i++) {
+		if (st->data_rate[i] == rate) {
+			st->channel_data[chan].data_rate = i;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int ads1018_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int *val,
+			    int *val2, long mask)
+{
+	int ret, idx;
+	struct ti_ads1018_state *st = iio_priv(indio_dev);
+
+	mutex_lock(&st->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW: {
+		int shift = chan->scan_type.shift;
+
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			break;
+
+		ret = ads1018_set_power_state(st, true);
+		if (ret < 0)
+			goto release_direct;
+
+		ret = ads1018_get_adc_result(st, chan->address, val);
+		if (ret < 0) {
+			ads1018_set_power_state(st, false);
+			goto release_direct;
+		}
+
+		*val = sign_extend32(*val >> shift, 15 - shift);
+
+		ret = ads1018_set_power_state(st, false);
+		if (ret < 0)
+			goto release_direct;
+
+		ret = IIO_VAL_INT;
+release_direct:
+		iio_device_release_direct_mode(indio_dev);
+		break;
+	}
+	case IIO_CHAN_INFO_SCALE:
+		idx = st->channel_data[chan->address].pga;
+		*val = ads1018_fullscale_range[idx];
+		*val2 = chan->scan_type.realbits - 1;
+		ret = IIO_VAL_FRACTIONAL_LOG2;
+		break;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		idx = st->channel_data[chan->address].data_rate;
+		*val = st->data_rate[idx];
+		ret = IIO_VAL_INT;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int ads1018_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int val,
+			     int val2, long mask)
+{
+	struct ti_ads1018_state *st = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&st->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		ret = ads1018_set_scale(st, chan, val, val2);
+		break;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		ret = ads1018_set_data_rate(st, chan->address, val);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int ads1018_buffer_preenable(struct iio_dev *indio_dev)
+{
+	return ads1018_set_power_state(iio_priv(indio_dev), true);
+}
+
+static int ads1018_buffer_postdisable(struct iio_dev *indio_dev)
+{
+	return ads1018_set_power_state(iio_priv(indio_dev), false);
+}
+
+static const struct iio_buffer_setup_ops ti_ads1018_buffer_setup_ops = {
+	.preenable	= ads1018_buffer_preenable,
+	.postdisable	= ads1018_buffer_postdisable,
+	.validate_scan_mask = &iio_validate_scan_mask_onehot,
+};
+
+static IIO_CONST_ATTR_NAMED(ads1018_scale_available, scale_available,
+	"3 2 1 0.5 0.25 0.125");
+
+static IIO_CONST_ATTR_NAMED(ads1018_sampling_frequency_available,
+	sampling_frequency_available, "128 250 490 920 1600 2400 3300");
+
+static struct attribute *ads1018_attributes[] = {
+	&iio_const_attr_ads1018_scale_available.dev_attr.attr,
+	&iio_const_attr_ads1018_sampling_frequency_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group ads1018_attribute_group = {
+	.attrs = ads1018_attributes,
+};
+
+
+static const struct iio_info ti_ads1018_info = {
+	.read_raw	= ads1018_read_raw,
+	.write_raw	= ads1018_write_raw,
+	.attrs          = &ads1018_attribute_group,
+};
+
+
+
+#ifdef CONFIG_OF
+static int ads1018_get_channels_config_of(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct ti_ads1018_state *data = iio_priv(indio_dev);
+	struct device_node *node;
+
+	if (!spi->dev.of_node ||
+	    !of_get_next_child(spi->dev.of_node, NULL))
+		return -EINVAL;
+
+	for_each_child_of_node(spi->dev.of_node, node) {
+		u32 pval;
+		unsigned int channel;
+		unsigned int pga = ADS1018_DEFAULT_PGA;
+		unsigned int data_rate = ADS1018_DEFAULT_DATA_RATE;
+
+		if (of_property_read_u32(node, "reg", &pval)) {
+			dev_err(&spi->dev, "invalid reg on %pOF\n",
+				node);
+			continue;
+		}
+
+		channel = pval;
+
+		if (channel >= ADS1018_CHANNELS) {
+			dev_err(&spi->dev,
+				"invalid channel index %d on %pOF\n",
+				channel, node);
+			continue;
+		}
+
+		if (!of_property_read_u32(node, "ti,gain", &pval)) {
+			pga = pval;
+			if (pga > 6) {
+				dev_err(&spi->dev, "invalid gain on %pOF\n",
+					node);
+				of_node_put(node);
+				return -EINVAL;
+			}
+		}
+
+		if (!of_property_read_u32(node, "ti,datarate", &pval)) {
+			data_rate = pval;
+			if (data_rate > 7) {
+				dev_err(&spi->dev,
+					"invalid data_rate on %pOF\n",
+					node);
+				of_node_put(node);
+				return -EINVAL;
+			}
+		}
+
+		data->channel_data[channel].enabled = 1;
+		data->channel_data[channel].pga = pga;
+		data->channel_data[channel].data_rate = data_rate;
+
+	}
+
+	return 0;
+}
+#endif
+
+static void ads1018_get_channels_config(struct spi_device *spi)
+{
+	unsigned int k;
+
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct ti_ads1018_state *data = iio_priv(indio_dev);
+#ifdef CONFIG_OF
+	if (!ads1018_get_channels_config_of(spi))
+		return;
+#endif
+	/* fallback on default configuration */
+	for (k = 0; k < ADS1018_CHANNELS; ++k) {
+		data->channel_data[k].enabled = 0;
+		data->channel_data[k].pga = ADS1018_DEFAULT_PGA;
+		data->channel_data[k].data_rate = ADS1018_DEFAULT_DATA_RATE;
+	}
+}
+
+static int ads1018_set_conv_mode(struct ti_ads1018_state *st, int mode)
+{
+	int updatedConfig;
+
+	updatedConfig = st->current_config & ~(TI_ADS1018_MODE_MASK << TI_ADS1018_MODE_SHIFT);
+	updatedConfig |= mode;
+
+	return ti_ads1018_write_config_register(st, updatedConfig);
+}
+
+
+static int ti_ads1018_set_trigger_state(struct iio_trigger *trig, bool enable)
+{
+	return 0;
+}
+
+
+static const struct iio_trigger_ops ti_ads1018_trigger_ops = {
+	.set_trigger_state = ti_ads1018_set_trigger_state,
+	.validate_device = iio_trigger_validate_own_device,
+};
+
+
+static int ti_ads1018_probe(struct spi_device *spi)
+{
+	struct ti_ads1018_state *st;
+	struct iio_dev *indio_dev;
+	const struct ti_ads1018_chip_info *info;
+	int ret;
+	int i;
+	int config;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+
+	st->spi = spi;
+	config = TI_ADS1018_CONFIGURE;
+	spi_set_drvdata(spi, indio_dev);
+
+	mutex_init(&st->lock);
+
+
+	info = &ti_ads1018_chip_info[TI_ADS1018];
+
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->modes = INDIO_DIRECT_MODE  |  INDIO_BUFFER_SOFTWARE;
+	indio_dev->channels = info->channels;
+	indio_dev->num_channels = info->num_channels;
+	indio_dev->info = &ti_ads1018_info;
+	st->data_rate = (unsigned int *) &ads1018_data_rate;
+
+	// allocate and then register trigger with IIO core
+	st->trig = iio_trigger_alloc(indio_dev->dev.parent, "%s-dev%d",
+					indio_dev->name,
+					iio_device_id(indio_dev));
+	if (st->trig == NULL) {
+		ret = -ENOMEM;
+		goto error_cleanup_ring;
+	}
+	st->trig->ops = &ti_ads1018_trigger_ops;
+
+	iio_trigger_register(st->trig);
+
+	// set the default trigger
+	indio_dev->trig = iio_trigger_get(st->trig);
+
+	ads1018_get_channels_config(spi);
+
+
+	/* Find out if DT has enabled any of the channels, only one allowed so
+	 * just take the first one
+	 */
+	for (i = 0; i < info->num_channels; i++)
+		if (st->channel_data[i].enabled == 1)
+			break;
+
+	/* If a channel was enabled set it by default in the device */
+	if (i < info->num_channels) {
+		/* mask out the mux bits  */
+		config &= ~(TI_ADS1018_MUX_MASK << TI_ADS1018_MUX_SHIFT);
+		config |= (i << TI_ADS1018_MUX_SHIFT);
+	}
+
+	/*
+	 * Always use 4 * 8 bit transfer mode so that the status is read back
+	 * in the second 16 bit word. This allows us to track when updated
+	 * configuration needs to be applied.
+	 */
+	st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
+	st->scan_single_xfer[0].rx_buf = &st->rx_buf[0];
+	st->scan_single_xfer[0].len = 4;
+	st->scan_single_xfer[0].cs_change = 0;
+	st->scan_single_xfer[0].bits_per_word = 8;
+
+	spi_message_init_with_transfers(&st->scan_single_msg,
+					st->scan_single_xfer, 1);
+
+	ret = ti_ads1018_write_config_register(st, config);
+	if (ret < 0) {
+		dev_err(&spi->dev, "ads1018 configuration failed\n");
+		return ret;
+	}
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+					 ti_ads1018_trigger_handler,
+					 &ti_ads1018_buffer_setup_ops);
+	if (ret < 0) {
+		dev_err(&spi->dev, "iio triggered buffer setup failed\n");
+		return ret;
+	}
+
+
+	ret = ads1018_set_conv_mode(st, TI_ADS1018_MODE_CONTINUOUS);
+	if (ret)
+		return ret;
+
+	st->conv_invalid = true;
+
+	ret = pm_runtime_set_active(&spi->dev);
+	if (ret)
+		return ret;
+	pm_runtime_set_autosuspend_delay(&spi->dev, ADS1018_SLEEP_DELAY_MS);
+	pm_runtime_use_autosuspend(&spi->dev);
+	pm_runtime_enable(&spi->dev);
+
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to register iio device\n");
+		goto error_cleanup_ring;
+	}
+
+	return 0;
+
+error_cleanup_ring:
+	iio_triggered_buffer_cleanup(indio_dev);
+
+	return ret;
+
+}
+
+static int ti_ads1018_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct ti_ads1018_state *st = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	pm_runtime_disable(&spi->dev);
+	pm_runtime_set_suspended(&spi->dev);
+	pm_runtime_put_noidle(&spi->dev);
+
+	/* power down single shot mode */
+	return ads1018_set_conv_mode(st, TI_ADS1018_MODE_SINGLE_SHOT);
+}
+
+
+
+#ifdef CONFIG_PM
+static int ads1018_runtime_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct ti_ads1018_state *st = iio_priv(indio_dev);
+
+	return ads1018_set_conv_mode(st, TI_ADS1018_MODE_SINGLE_SHOT);
+}
+
+static int ads1018_runtime_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct ti_ads1018_state *st = iio_priv(indio_dev);
+	int ret;
+
+	ret = ads1018_set_conv_mode(st, TI_ADS1018_MODE_CONTINUOUS);
+	if (!ret)
+		st->conv_invalid = true;
+
+	return ret;
+}
+#endif
+
+static const struct dev_pm_ops ads1018_pm_ops = {
+	SET_RUNTIME_PM_OPS(ads1018_runtime_suspend,
+			   ads1018_runtime_resume, NULL)
+};
+
+static const struct spi_device_id ti_ads1018_id[] = {
+	{ "ads1018", TI_ADS1018 },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ti_ads1018_id);
+
+static const struct of_device_id ads1018_of_table[] = {
+	{ .compatible = "ti,ads1018", .data = &ti_ads1018_chip_info[TI_ADS1018] },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ads1018_of_table);
+
+static struct spi_driver ti_ads1018_driver = {
+	.driver = {
+		.name = ADS1018_DRV_NAME,
+		.of_match_table = ads1018_of_table,
+		.pm = &ads1018_pm_ops,
+	},
+	.probe		= ti_ads1018_probe,
+	.remove		= ti_ads1018_remove,
+	.id_table	= ti_ads1018_id,
+};
+module_spi_driver(ti_ads1018_driver);
+
+MODULE_AUTHOR("Iain Hunter <iain@...terembedded.co.uk>");
+MODULE_DESCRIPTION("TI TI_ADS1018 ADC");
+MODULE_LICENSE("GPL v2");
-- 
2.25.1

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