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From:   <alexandru.tachici@analog.com>
To:     <linux-iio@vger.kernel.org>, <linux-kernel@vger.kernel.org>
CC:     <jic23@kernel.org>
Subject: [PATCH v5 1/1] iio: adc: ad7124: allow more than 8 channels
Date:   Thu, 11 Mar 2021 11:11:54 +0200
Message-ID: <20210311091154.47785-2-alexandru.tachici@analog.com>
In-Reply-To: <20210311091154.47785-1-alexandru.tachici@analog.com>
References: <20210311091154.47785-1-alexandru.tachici@analog.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

From: Alexandru Tachici <alexandru.tachici@analog.com>

Currently AD7124-8 driver cannot use more than 8 IIO channels
because it was assigning the channel configurations bijectively
to channels specified in the device-tree. This is not possible
to do when using more than 8 channels as AD7124-8 has only 8
configuration registers.

To allow the user to use all channels at once the driver
will keep in memory configurations for all channels but
will program only 8 of them at a time on the device.
If multiple channels have the same configuration, only
one configuration register will be used. If there
are more configurations than available registers only
the last 8 used configurations will be allowed to exist
on the device in a LRU fashion.

Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
---
 drivers/iio/adc/ad7124.c | 458 +++++++++++++++++++++++++--------------
 1 file changed, 301 insertions(+), 157 deletions(-)

diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index 766c73333604..8b5b223938e8 100644
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -5,12 +5,14 @@
  * Copyright 2018 Analog Devices Inc.
  */
 #include <linux/bitfield.h>
+#include <linux/bitops.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
+#include <linux/kfifo.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/regulator/consumer.h>
@@ -86,6 +88,10 @@
 #define AD7124_SINC3_FILTER 2
 #define AD7124_SINC4_FILTER 0
 
+#define AD7124_CONF_ADDR_OFFSET	20
+#define AD7124_MAX_CONFIGS	8
+#define AD7124_MAX_CHANNELS	16
+
 enum ad7124_ids {
 	ID_AD7124_4,
 	ID_AD7124_8,
@@ -136,25 +142,37 @@ struct ad7124_chip_info {
 };
 
 struct ad7124_channel_config {
+	bool live;
+	unsigned int cfg_slot;
 	enum ad7124_ref_sel refsel;
 	bool bipolar;
 	bool buf_positive;
 	bool buf_negative;
-	unsigned int ain;
 	unsigned int vref_mv;
 	unsigned int pga_bits;
 	unsigned int odr;
+	unsigned int odr_sel_bits;
 	unsigned int filter_type;
 };
 
+struct ad7124_channel {
+	unsigned int nr;
+	struct ad7124_channel_config cfg;
+	unsigned int ain;
+	unsigned int slot;
+};
+
 struct ad7124_state {
 	const struct ad7124_chip_info *chip_info;
 	struct ad_sigma_delta sd;
-	struct ad7124_channel_config *channel_config;
+	struct ad7124_channel *channels;
 	struct regulator *vref[4];
 	struct clk *mclk;
 	unsigned int adc_control;
 	unsigned int num_channels;
+	struct mutex cfgs_lock; /* lock for configs access */
+	unsigned long cfg_slots_status; /* bitmap with slot status (1 means it is used) */
+	DECLARE_KFIFO(live_cfgs_fifo, struct ad7124_channel_config *, AD7124_MAX_CONFIGS);
 };
 
 static const struct iio_chan_spec ad7124_channel_template = {
@@ -238,33 +256,9 @@ static int ad7124_set_mode(struct ad_sigma_delta *sd,
 	return ad_sd_write_reg(&st->sd, AD7124_ADC_CONTROL, 2, st->adc_control);
 }
 
-static int ad7124_set_channel(struct ad_sigma_delta *sd, unsigned int channel)
-{
-	struct ad7124_state *st = container_of(sd, struct ad7124_state, sd);
-	unsigned int val;
-
-	val = st->channel_config[channel].ain | AD7124_CHANNEL_EN(1) |
-	      AD7124_CHANNEL_SETUP(channel);
-
-	return ad_sd_write_reg(&st->sd, AD7124_CHANNEL(channel), 2, val);
-}
-
-static const struct ad_sigma_delta_info ad7124_sigma_delta_info = {
-	.set_channel = ad7124_set_channel,
-	.set_mode = ad7124_set_mode,
-	.has_registers = true,
-	.addr_shift = 0,
-	.read_mask = BIT(6),
-	.data_reg = AD7124_DATA,
-	.irq_flags = IRQF_TRIGGER_FALLING,
-};
-
-static int ad7124_set_channel_odr(struct ad7124_state *st,
-				  unsigned int channel,
-				  unsigned int odr)
+static void ad7124_set_channel_odr(struct ad7124_state *st, unsigned int channel, unsigned int odr)
 {
 	unsigned int fclk, odr_sel_bits;
-	int ret;
 
 	fclk = clk_get_rate(st->mclk);
 	/*
@@ -280,36 +274,12 @@ static int ad7124_set_channel_odr(struct ad7124_state *st,
 	else if (odr_sel_bits > 2047)
 		odr_sel_bits = 2047;
 
-	ret = ad7124_spi_write_mask(st, AD7124_FILTER(channel),
-				    AD7124_FILTER_FS_MSK,
-				    AD7124_FILTER_FS(odr_sel_bits), 3);
-	if (ret < 0)
-		return ret;
-	/* fADC = fCLK / (FS[10:0] x 32) */
-	st->channel_config[channel].odr =
-		DIV_ROUND_CLOSEST(fclk, odr_sel_bits * 32);
-
-	return 0;
-}
-
-static int ad7124_set_channel_gain(struct ad7124_state *st,
-				   unsigned int channel,
-				   unsigned int gain)
-{
-	unsigned int res;
-	int ret;
-
-	res = ad7124_find_closest_match(ad7124_gain,
-					ARRAY_SIZE(ad7124_gain), gain);
-	ret = ad7124_spi_write_mask(st, AD7124_CONFIG(channel),
-				    AD7124_CONFIG_PGA_MSK,
-				    AD7124_CONFIG_PGA(res), 2);
-	if (ret < 0)
-		return ret;
-
-	st->channel_config[channel].pga_bits = res;
+	if (odr_sel_bits != st->channels[channel].cfg.odr_sel_bits)
+		st->channels[channel].cfg.live = false;
 
-	return 0;
+	/* fADC = fCLK / (FS[10:0] x 32) */
+	st->channels[channel].cfg.odr = DIV_ROUND_CLOSEST(fclk, odr_sel_bits * 32);
+	st->channels[channel].cfg.odr_sel_bits = odr_sel_bits;
 }
 
 static int ad7124_get_3db_filter_freq(struct ad7124_state *st,
@@ -317,9 +287,9 @@ static int ad7124_get_3db_filter_freq(struct ad7124_state *st,
 {
 	unsigned int fadc;
 
-	fadc = st->channel_config[channel].odr;
+	fadc = st->channels[channel].cfg.odr;
 
-	switch (st->channel_config[channel].filter_type) {
+	switch (st->channels[channel].cfg.filter_type) {
 	case AD7124_SINC3_FILTER:
 		return DIV_ROUND_CLOSEST(fadc * 230, 1000);
 	case AD7124_SINC4_FILTER:
@@ -329,9 +299,8 @@ static int ad7124_get_3db_filter_freq(struct ad7124_state *st,
 	}
 }
 
-static int ad7124_set_3db_filter_freq(struct ad7124_state *st,
-				      unsigned int channel,
-				      unsigned int freq)
+static void ad7124_set_3db_filter_freq(struct ad7124_state *st, unsigned int channel,
+				       unsigned int freq)
 {
 	unsigned int sinc4_3db_odr;
 	unsigned int sinc3_3db_odr;
@@ -349,21 +318,211 @@ static int ad7124_set_3db_filter_freq(struct ad7124_state *st,
 		new_odr = sinc3_3db_odr;
 	}
 
-	if (st->channel_config[channel].filter_type != new_filter) {
-		int ret;
+	if (new_odr != st->channels[channel].cfg.odr)
+		st->channels[channel].cfg.live = false;
 
-		st->channel_config[channel].filter_type = new_filter;
-		ret = ad7124_spi_write_mask(st, AD7124_FILTER(channel),
-					    AD7124_FILTER_TYPE_MSK,
-					    AD7124_FILTER_TYPE_SEL(new_filter),
-					    3);
-		if (ret < 0)
-			return ret;
+	st->channels[channel].cfg.filter_type = new_filter;
+	st->channels[channel].cfg.odr = new_odr;
+}
+
+static struct ad7124_channel_config *ad7124_find_similar_live_cfg(struct ad7124_state *st,
+								  struct ad7124_channel_config *cfg)
+{
+	struct ad7124_channel_config *cfg_aux;
+	ptrdiff_t cmp_size;
+	int i;
+
+	cmp_size = (u8 *)&cfg->live - (u8 *)cfg;
+	for (i = 0; i < st->num_channels; i++) {
+		cfg_aux = &st->channels[i].cfg;
+
+		if (cfg_aux->live && !memcmp(cfg, cfg_aux, cmp_size))
+			return cfg_aux;
+	}
+
+	return NULL;
+}
+
+static int ad7124_find_free_config_slot(struct ad7124_state *st)
+{
+	unsigned int free_cfg_slot;
+
+	free_cfg_slot = find_next_zero_bit(&st->cfg_slots_status, AD7124_MAX_CONFIGS, 0);
+	if (free_cfg_slot == AD7124_MAX_CONFIGS)
+		return -1;
+
+	return free_cfg_slot;
+}
+
+static int ad7124_init_config_vref(struct ad7124_state *st, struct ad7124_channel_config *cfg)
+{
+	unsigned int refsel = cfg->refsel;
+
+	switch (refsel) {
+	case AD7124_REFIN1:
+	case AD7124_REFIN2:
+	case AD7124_AVDD_REF:
+		if (IS_ERR(st->vref[refsel])) {
+			dev_err(&st->sd.spi->dev,
+				"Error, trying to use external voltage reference without a %s regulator.\n",
+				ad7124_ref_names[refsel]);
+				return PTR_ERR(st->vref[refsel]);
+		}
+		cfg->vref_mv = regulator_get_voltage(st->vref[refsel]);
+		/* Conversion from uV to mV */
+		cfg->vref_mv /= 1000;
+		return 0;
+	case AD7124_INT_REF:
+		cfg->vref_mv = 2500;
+		st->adc_control &= ~AD7124_ADC_CTRL_REF_EN_MSK;
+		st->adc_control |= AD7124_ADC_CTRL_REF_EN(1);
+		return ad_sd_write_reg(&st->sd, AD7124_ADC_CONTROL,
+				      2, st->adc_control);
+	default:
+		dev_err(&st->sd.spi->dev, "Invalid reference %d\n", refsel);
+		return -EINVAL;
+	}
+}
+
+static int ad7124_write_config(struct ad7124_state *st, struct ad7124_channel_config *cfg,
+			       unsigned int cfg_slot)
+{
+	unsigned int tmp;
+	unsigned int val;
+	int ret;
+
+	cfg->cfg_slot = cfg_slot;
+
+	tmp = (cfg->buf_positive << 1) + cfg->buf_negative;
+	val = AD7124_CONFIG_BIPOLAR(cfg->bipolar) | AD7124_CONFIG_REF_SEL(cfg->refsel) |
+	      AD7124_CONFIG_IN_BUFF(tmp);
+	ret = ad_sd_write_reg(&st->sd, AD7124_CONFIG(cfg->cfg_slot), 2, val);
+	if (ret < 0)
+		return ret;
+
+	tmp = AD7124_FILTER_TYPE_SEL(cfg->filter_type);
+	ret = ad7124_spi_write_mask(st, AD7124_FILTER(cfg->cfg_slot), AD7124_FILTER_TYPE_MSK,
+				    tmp, 3);
+	if (ret < 0)
+		return ret;
+
+	ret = ad7124_spi_write_mask(st, AD7124_FILTER(cfg->cfg_slot), AD7124_FILTER_FS_MSK,
+				    AD7124_FILTER_FS(cfg->odr_sel_bits), 3);
+	if (ret < 0)
+		return ret;
+
+	return ad7124_spi_write_mask(st, AD7124_CONFIG(cfg->cfg_slot), AD7124_CONFIG_PGA_MSK,
+				     AD7124_CONFIG_PGA(cfg->pga_bits), 2);
+}
+
+static struct ad7124_channel_config *ad7124_pop_config(struct ad7124_state *st)
+{
+	struct ad7124_channel_config *lru_cfg;
+	struct ad7124_channel_config *cfg;
+	int ret;
+	int i;
+
+	/*
+	 * Pop least recently used config from the fifo
+	 * in order to make room for the new one
+	 */
+	ret = kfifo_get(&st->live_cfgs_fifo, &lru_cfg);
+	if (ret <= 0)
+		return NULL;
+
+	lru_cfg->live = false;
+
+	/* mark slot as free */
+	assign_bit(lru_cfg->cfg_slot, &st->cfg_slots_status, 0);
+
+	/* invalidate all other configs that pointed to this one */
+	for (i = 0; i < st->num_channels; i++) {
+		cfg = &st->channels[i].cfg;
+
+		if (cfg->cfg_slot == lru_cfg->cfg_slot)
+			cfg->live = false;
 	}
 
-	return ad7124_set_channel_odr(st, channel, new_odr);
+	return lru_cfg;
 }
 
+static int ad7124_push_config(struct ad7124_state *st, struct ad7124_channel_config *cfg)
+{
+	struct ad7124_channel_config *lru_cfg;
+	int free_cfg_slot;
+
+	free_cfg_slot = ad7124_find_free_config_slot(st);
+	if (free_cfg_slot >= 0) {
+		/* push the new config in configs queue */
+		kfifo_put(&st->live_cfgs_fifo, cfg);
+	} else {
+		/* pop one config to make room for the new one */
+		lru_cfg = ad7124_pop_config(st);
+		if (!lru_cfg)
+			return -EINVAL;
+
+		/* push the new config in configs queue */
+		free_cfg_slot = lru_cfg->cfg_slot;
+		kfifo_put(&st->live_cfgs_fifo, cfg);
+	}
+
+	/* mark slot as used */
+	assign_bit(free_cfg_slot, &st->cfg_slots_status, 1);
+
+	return ad7124_write_config(st, cfg, free_cfg_slot);
+}
+
+static int ad7124_enable_channel(struct ad7124_state *st, struct ad7124_channel *ch)
+{
+	ch->cfg.live = true;
+	return ad_sd_write_reg(&st->sd, AD7124_CHANNEL(ch->nr), 2, ch->ain |
+			      AD7124_CHANNEL_SETUP(ch->cfg.cfg_slot) | AD7124_CHANNEL_EN(1));
+}
+
+static int ad7124_prepare_read(struct ad7124_state *st, int address)
+{
+	struct ad7124_channel_config *cfg = &st->channels[address].cfg;
+	struct ad7124_channel_config *live_cfg;
+
+	/*
+	 * Before doing any reads assign the channel a configuration.
+	 * Check if channel's config is on the device
+	 */
+	if (!cfg->live) {
+		/* check if config matches another one */
+		live_cfg = ad7124_find_similar_live_cfg(st, cfg);
+		if (!live_cfg)
+			ad7124_push_config(st, cfg);
+		else
+			cfg->cfg_slot = live_cfg->cfg_slot;
+	}
+
+	/* point channel to the config slot and enable */
+	return ad7124_enable_channel(st, &st->channels[address]);
+}
+
+static int ad7124_set_channel(struct ad_sigma_delta *sd, unsigned int channel)
+{
+	struct ad7124_state *st = container_of(sd, struct ad7124_state, sd);
+	int ret;
+
+	mutex_lock(&st->cfgs_lock);
+	ret = ad7124_prepare_read(st, channel);
+	mutex_unlock(&st->cfgs_lock);
+
+	return ret;
+}
+
+static const struct ad_sigma_delta_info ad7124_sigma_delta_info = {
+	.set_channel = ad7124_set_channel,
+	.set_mode = ad7124_set_mode,
+	.has_registers = true,
+	.addr_shift = 0,
+	.read_mask = BIT(6),
+	.data_reg = AD7124_DATA,
+	.irq_flags = IRQF_TRIGGER_FALLING
+};
+
 static int ad7124_read_raw(struct iio_dev *indio_dev,
 			   struct iio_chan_spec const *chan,
 			   int *val, int *val2, long info)
@@ -378,36 +537,44 @@ static int ad7124_read_raw(struct iio_dev *indio_dev,
 			return ret;
 
 		/* After the conversion is performed, disable the channel */
-		ret = ad_sd_write_reg(&st->sd,
-				      AD7124_CHANNEL(chan->address), 2,
-				      st->channel_config[chan->address].ain |
-				      AD7124_CHANNEL_EN(0));
+		ret = ad_sd_write_reg(&st->sd, AD7124_CHANNEL(chan->address), 2,
+				      st->channels[chan->address].ain | AD7124_CHANNEL_EN(0));
 		if (ret < 0)
 			return ret;
 
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
-		idx = st->channel_config[chan->address].pga_bits;
-		*val = st->channel_config[chan->address].vref_mv;
-		if (st->channel_config[chan->address].bipolar)
+		mutex_lock(&st->cfgs_lock);
+
+		idx = st->channels[chan->address].cfg.pga_bits;
+		*val = st->channels[chan->address].cfg.vref_mv;
+		if (st->channels[chan->address].cfg.bipolar)
 			*val2 = chan->scan_type.realbits - 1 + idx;
 		else
 			*val2 = chan->scan_type.realbits + idx;
 
+		mutex_unlock(&st->cfgs_lock);
 		return IIO_VAL_FRACTIONAL_LOG2;
 	case IIO_CHAN_INFO_OFFSET:
-		if (st->channel_config[chan->address].bipolar)
+		mutex_lock(&st->cfgs_lock);
+		if (st->channels[chan->address].cfg.bipolar)
 			*val = -(1 << (chan->scan_type.realbits - 1));
 		else
 			*val = 0;
 
+		mutex_unlock(&st->cfgs_lock);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SAMP_FREQ:
-		*val = st->channel_config[chan->address].odr;
+		mutex_lock(&st->cfgs_lock);
+		*val = st->channels[chan->address].cfg.odr;
+		mutex_unlock(&st->cfgs_lock);
 
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
+		mutex_lock(&st->cfgs_lock);
 		*val = ad7124_get_3db_filter_freq(st, chan->scan_index);
+		mutex_unlock(&st->cfgs_lock);
+
 		return IIO_VAL_INT;
 	default:
 		return -EINVAL;
@@ -420,35 +587,54 @@ static int ad7124_write_raw(struct iio_dev *indio_dev,
 {
 	struct ad7124_state *st = iio_priv(indio_dev);
 	unsigned int res, gain, full_scale, vref;
+	int ret = 0;
+
+	mutex_lock(&st->cfgs_lock);
 
 	switch (info) {
 	case IIO_CHAN_INFO_SAMP_FREQ:
-		if (val2 != 0)
-			return -EINVAL;
+		if (val2 != 0) {
+			ret = -EINVAL;
+			break;
+		}
 
-		return ad7124_set_channel_odr(st, chan->address, val);
+		ad7124_set_channel_odr(st, chan->address, val);
+		break;
 	case IIO_CHAN_INFO_SCALE:
-		if (val != 0)
-			return -EINVAL;
+		if (val != 0) {
+			ret = -EINVAL;
+			break;
+		}
 
-		if (st->channel_config[chan->address].bipolar)
+		if (st->channels[chan->address].cfg.bipolar)
 			full_scale = 1 << (chan->scan_type.realbits - 1);
 		else
 			full_scale = 1 << chan->scan_type.realbits;
 
-		vref = st->channel_config[chan->address].vref_mv * 1000000LL;
+		vref = st->channels[chan->address].cfg.vref_mv * 1000000LL;
 		res = DIV_ROUND_CLOSEST(vref, full_scale);
 		gain = DIV_ROUND_CLOSEST(res, val2);
+		res = ad7124_find_closest_match(ad7124_gain, ARRAY_SIZE(ad7124_gain), gain);
 
-		return ad7124_set_channel_gain(st, chan->address, gain);
+		if (st->channels[chan->address].cfg.pga_bits != res)
+			st->channels[chan->address].cfg.live = false;
+
+		st->channels[chan->address].cfg.pga_bits = res;
+		break;
 	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
-		if (val2 != 0)
-			return -EINVAL;
+		if (val2 != 0) {
+			ret = -EINVAL;
+			break;
+		}
 
-		return ad7124_set_3db_filter_freq(st, chan->address, val);
+		ad7124_set_3db_filter_freq(st, chan->address, val);
+		break;
 	default:
-		return -EINVAL;
+		ret =  -EINVAL;
 	}
+
+	mutex_unlock(&st->cfgs_lock);
+	return ret;
 }
 
 static int ad7124_reg_access(struct iio_dev *indio_dev,
@@ -547,47 +733,14 @@ static int ad7124_check_chip_id(struct ad7124_state *st)
 	return 0;
 }
 
-static int ad7124_init_channel_vref(struct ad7124_state *st,
-				    unsigned int channel_number)
-{
-	unsigned int refsel = st->channel_config[channel_number].refsel;
-
-	switch (refsel) {
-	case AD7124_REFIN1:
-	case AD7124_REFIN2:
-	case AD7124_AVDD_REF:
-		if (IS_ERR(st->vref[refsel])) {
-			dev_err(&st->sd.spi->dev,
-				"Error, trying to use external voltage reference without a %s regulator.\n",
-				ad7124_ref_names[refsel]);
-			return PTR_ERR(st->vref[refsel]);
-		}
-		st->channel_config[channel_number].vref_mv =
-			regulator_get_voltage(st->vref[refsel]);
-		/* Conversion from uV to mV */
-		st->channel_config[channel_number].vref_mv /= 1000;
-		break;
-	case AD7124_INT_REF:
-		st->channel_config[channel_number].vref_mv = 2500;
-		st->adc_control &= ~AD7124_ADC_CTRL_REF_EN_MSK;
-		st->adc_control |= AD7124_ADC_CTRL_REF_EN(1);
-		return ad_sd_write_reg(&st->sd, AD7124_ADC_CONTROL,
-				      2, st->adc_control);
-	default:
-		dev_err(&st->sd.spi->dev, "Invalid reference %d\n", refsel);
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
 static int ad7124_of_parse_channel_config(struct iio_dev *indio_dev,
 					  struct device_node *np)
 {
 	struct ad7124_state *st = iio_priv(indio_dev);
+	struct ad7124_channel_config *cfg;
+	struct ad7124_channel *channels;
 	struct device_node *child;
 	struct iio_chan_spec *chan;
-	struct ad7124_channel_config *chan_config;
 	unsigned int ain[2], channel = 0, tmp;
 	int ret;
 
@@ -602,16 +755,18 @@ static int ad7124_of_parse_channel_config(struct iio_dev *indio_dev,
 	if (!chan)
 		return -ENOMEM;
 
-	chan_config = devm_kcalloc(indio_dev->dev.parent, st->num_channels,
-				   sizeof(*chan_config), GFP_KERNEL);
-	if (!chan_config)
+	channels = devm_kcalloc(indio_dev->dev.parent, st->num_channels, sizeof(*channels),
+				GFP_KERNEL);
+	if (!channels)
 		return -ENOMEM;
 
 	indio_dev->channels = chan;
 	indio_dev->num_channels = st->num_channels;
-	st->channel_config = chan_config;
+	st->channels = channels;
 
 	for_each_available_child_of_node(np, child) {
+		cfg = &st->channels[channel].cfg;
+
 		ret = of_property_read_u32(child, "reg", &channel);
 		if (ret)
 			goto err;
@@ -621,21 +776,20 @@ static int ad7124_of_parse_channel_config(struct iio_dev *indio_dev,
 		if (ret)
 			goto err;
 
-		st->channel_config[channel].ain = AD7124_CHANNEL_AINP(ain[0]) |
+		st->channels[channel].nr = channel;
+		st->channels[channel].ain = AD7124_CHANNEL_AINP(ain[0]) |
 						  AD7124_CHANNEL_AINM(ain[1]);
-		st->channel_config[channel].bipolar =
-			of_property_read_bool(child, "bipolar");
+
+		cfg->bipolar = of_property_read_bool(child, "bipolar");
 
 		ret = of_property_read_u32(child, "adi,reference-select", &tmp);
 		if (ret)
-			st->channel_config[channel].refsel = AD7124_INT_REF;
+			cfg->refsel = AD7124_INT_REF;
 		else
-			st->channel_config[channel].refsel = tmp;
+			cfg->refsel = tmp;
 
-		st->channel_config[channel].buf_positive =
-			of_property_read_bool(child, "adi,buffered-positive");
-		st->channel_config[channel].buf_negative =
-			of_property_read_bool(child, "adi,buffered-negative");
+		cfg->buf_positive = of_property_read_bool(child, "adi,buffered-positive");
+		cfg->buf_negative = of_property_read_bool(child, "adi,buffered-negative");
 
 		chan[channel] = ad7124_channel_template;
 		chan[channel].address = channel;
@@ -654,7 +808,7 @@ static int ad7124_of_parse_channel_config(struct iio_dev *indio_dev,
 static int ad7124_setup(struct ad7124_state *st)
 {
 	unsigned int val, fclk, power_mode;
-	int i, ret, tmp;
+	int i, ret;
 
 	fclk = clk_get_rate(st->mclk);
 	if (!fclk)
@@ -677,31 +831,21 @@ static int ad7124_setup(struct ad7124_state *st)
 	if (ret < 0)
 		return ret;
 
+	mutex_init(&st->cfgs_lock);
+	INIT_KFIFO(st->live_cfgs_fifo);
 	for (i = 0; i < st->num_channels; i++) {
-		val = st->channel_config[i].ain | AD7124_CHANNEL_SETUP(i);
-		ret = ad_sd_write_reg(&st->sd, AD7124_CHANNEL(i), 2, val);
-		if (ret < 0)
-			return ret;
+		val = st->channels[i].ain;
 
-		ret = ad7124_init_channel_vref(st, i);
+		ret = ad7124_init_config_vref(st, &st->channels[i].cfg);
 		if (ret < 0)
 			return ret;
 
-		tmp = (st->channel_config[i].buf_positive << 1)  +
-			st->channel_config[i].buf_negative;
-
-		val = AD7124_CONFIG_BIPOLAR(st->channel_config[i].bipolar) |
-		      AD7124_CONFIG_REF_SEL(st->channel_config[i].refsel) |
-		      AD7124_CONFIG_IN_BUFF(tmp);
-		ret = ad_sd_write_reg(&st->sd, AD7124_CONFIG(i), 2, val);
-		if (ret < 0)
-			return ret;
 		/*
 		 * 9.38 SPS is the minimum output data rate supported
 		 * regardless of the selected power mode. Round it up to 10 and
-		 * set all the enabled channels to this default value.
+		 * set all channels to this default value.
 		 */
-		ret = ad7124_set_channel_odr(st, i, 10);
+		ad7124_set_channel_odr(st, i, 10);
 	}
 
 	return ret;
-- 
2.20.1