[PATCH v3 0/6] iio: adc: ad_sigma_delta: Add sequencer support

[PATCH v3 0/6] iio: adc: ad_sigma_delta: Add sequencer support

[alexandru.tachici]

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

Some sigma-delta chips support sampling of multiple
channels in continuous mode.

When the operating with more than one channel enabled,
the channel sequencer cycles through the enabled channels
in sequential order, from first channel to the last one.
If a channel is disabled, it is skipped by the sequencer.

If more than one channel is used in continuous mode,
instruct the device to append the status to the SPI transfer
(1 extra byte) every time we receive a sample.
All sigma-delta chips possessing a sampling sequencer have
this ability. Inside the status register there will be
the number of the converted channel. In this way, even
if the CPU won't keep up with the sampling rate, it won't
send to userspace wrong channel samples.

1. Removed the 1 byte .shift from channel spec in AD7124,
it confuses userspace apps (no need to shift right).

2. Add update_scan_mode to AD7124, it is required in order
to enable/disable multiple channels at once

3. Add update_scan_mode to AD7192, it is required in order
to enable/disable multiple channels at once

4. Add sequencer support for sigma_delta library.

5. Add sigma_delta_info values and callbacks for sequencer
support in AD7124.

6. Add sigma_delta_info values and callbacks for sequencer
support in AD7192.

Alexandru Tachici (5):
  iio: adc: ad7124: Remove shift from scan_type
  iio: adc: ad7124: Add update_scan_mode
  iio: adc: ad7192: Add update_scan_mode
  iio: adc: ad7124: add sequencer support
  iio: adc: ad7192: add sequencer support

Lars-Peter Clausen (1):
  iio: adc: ad_sigma_delta: Add sequencer support

Changelog V2 -> V3:
  - ad_sd_buffer_postenable(), aligned (slot * storagebits) to 8 bytes
  - devm_krealloc instead of krealloc for samples_buf in ad_sd_buffer_postenable()
  - in ad_sigma_delta_append_status, check return value before setting .status_appended
  - iio: adc: ad_sigma_delta: Add sequencer support: added explanations on
  desynchronization checking and recovery
  - in ad7124_append_status() modify st->adc_control after write has taken place without errors
  - in ad7124_update_scan_mode() take cfg mutex only once instead of every time a
  set_channel happens
  - in ad7192_disable_all() modify st->conf after write taken place without errors
  - in ad7192_append_status() modify st->mode after write taken place without errors

 drivers/iio/adc/ad7124.c               |  86 ++++++++++++++-
 drivers/iio/adc/ad7192.c               |  64 ++++++++++-
 drivers/iio/adc/ad_sigma_delta.c       | 143 +++++++++++++++++++++++--
 include/linux/iio/adc/ad_sigma_delta.h |  38 +++++++
 4 files changed, 315 insertions(+), 16 deletions(-)

--
2.25.1

[PATCH v3 1/6] iio: adc: ad7124: Remove shift from scan_type

[alexandru.tachici]

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

The 24 bits data is stored in 32 bits in BE. There
is no need to shift it. This confuses user-space apps.

Fixes: b3af341bbd966 ("iio: adc: Add ad7124 support")
Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
---
 drivers/iio/adc/ad7124.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index 998a342d51a6..7249db2c4422 100644
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -188,7 +188,6 @@ static const struct iio_chan_spec ad7124_channel_template = {
 		.sign = 'u',
 		.realbits = 24,
 		.storagebits = 32,
-		.shift = 8,
 		.endianness = IIO_BE,
 	},
 };
-- 
2.25.1

[PATCH v3 2/6] iio: adc: ad7124: Add update_scan_mode

[alexandru.tachici]

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

The callback .set_channel cannot be used to enable and
disable multiple channels at once as they are presented
in the active_scan_mask.

By adding an update_scan_mode callback, every time the
continuous mode is activated, channels will be
enabled/disabled accordingly.

Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
---
 drivers/iio/adc/ad7124.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index 7249db2c4422..428ec3e257d7 100644
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -669,11 +669,32 @@ static const struct attribute_group ad7124_attrs_group = {
 	.attrs = ad7124_attributes,
 };
 
+static int ad7124_update_scan_mode(struct iio_dev *indio_dev,
+				   const unsigned long *scan_mask)
+{
+	struct ad7124_state *st = iio_priv(indio_dev);
+	bool bit_set;
+	int ret;
+	int i;
+
+	for (i = 0; i < st->num_channels; i++) {
+		bit_set = test_bit(i, scan_mask);
+		ret = ad7124_spi_write_mask(st, AD7124_CHANNEL(i),
+					    AD7124_CHANNEL_EN_MSK,
+					    AD7124_CHANNEL_EN(bit_set),
+					    2);
+		if (ret < 0)
+			return ret;
+	}
+	return 0;
+}
+
 static const struct iio_info ad7124_info = {
 	.read_raw = ad7124_read_raw,
 	.write_raw = ad7124_write_raw,
 	.debugfs_reg_access = &ad7124_reg_access,
 	.validate_trigger = ad_sd_validate_trigger,
+	.update_scan_mode = ad7124_update_scan_mode,
 	.attrs = &ad7124_attrs_group,
 };
 
-- 
2.25.1

[PATCH v3 3/6] iio: adc: ad7192: Add update_scan_mode

[alexandru.tachici]

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

The callback .set_channel cannot be used to enable multiple
channels at once, only one is allowed simultaneously.

By adding an update_scan_mode callback, every time the
continuous mode is activated, channels will be enabled/disabled
accordingly.

Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
---
 drivers/iio/adc/ad7192.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/iio/adc/ad7192.c b/drivers/iio/adc/ad7192.c
index 770b4e59238f..4c004af4749f 100644
--- a/drivers/iio/adc/ad7192.c
+++ b/drivers/iio/adc/ad7192.c
@@ -783,6 +783,26 @@ static int ad7192_read_avail(struct iio_dev *indio_dev,
 	return -EINVAL;
 }
 
+static int ad7192_update_scan_mode(struct iio_dev *indio_dev, const unsigned long *scan_mask)
+{
+	struct ad7192_state *st = iio_priv(indio_dev);
+	u32 conf = st->conf;
+	int ret;
+	int i;
+
+	conf &= ~AD7192_CONF_CHAN_MASK;
+	for_each_set_bit(i, scan_mask, 8)
+		conf |= AD7192_CONF_CHAN(i);
+
+	ret = ad_sd_write_reg(&st->sd, AD7192_REG_CONF, 3, conf);
+	if (ret < 0)
+		return ret;
+
+	st->conf = conf;
+
+	return 0;
+}
+
 static const struct iio_info ad7192_info = {
 	.read_raw = ad7192_read_raw,
 	.write_raw = ad7192_write_raw,
@@ -790,6 +810,7 @@ static const struct iio_info ad7192_info = {
 	.read_avail = ad7192_read_avail,
 	.attrs = &ad7192_attribute_group,
 	.validate_trigger = ad_sd_validate_trigger,
+	.update_scan_mode = ad7192_update_scan_mode,
 };
 
 static const struct iio_info ad7195_info = {
@@ -799,6 +820,7 @@ static const struct iio_info ad7195_info = {
 	.read_avail = ad7192_read_avail,
 	.attrs = &ad7195_attribute_group,
 	.validate_trigger = ad_sd_validate_trigger,
+	.update_scan_mode = ad7192_update_scan_mode,
 };
 
 #define __AD719x_CHANNEL(_si, _channel1, _channel2, _address, _extend_name, \
-- 
2.25.1

[PATCH v3 4/6] iio: adc: ad_sigma_delta: Add sequencer support

[alexandru.tachici]

From: Lars-Peter Clausen <lars@metafoo.de>

Some sigma-delta chips support sampling of multiple
channels in continuous mode.

When the operating with more than one channel enabled,
the channel sequencer cycles through the enabled channels
in sequential order, from first channel to the last one.
If a channel is disabled, it is skipped by the sequencer.

If more than one channel is used in continuous mode,
instruct the device to append the status to the SPI transfer
(1 extra byte) every time we receive a sample.
All sigma-delta chips possessing a sampling sequencer have
this ability. Inside the status register there will be
the number of the converted channel. In this way, even
if the CPU won't keep up with the sampling rate, it won't
send to userspace wrong channel samples.

When multiple channels are enabled in continuous mode,
the device needs to perform a measurement on all slots
before we can push to userspace the sample.

If, during sequencing and data reading, a channel measurement
is lost, a desync occurred. In this case, ad_sigma_delta drops
the incomplete sample and waits for the device to send the
measurement on the first active slot.

Co-developed-by: Alexandru Tachici <alexandru.tachici@analog.com>
Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
 drivers/iio/adc/ad_sigma_delta.c       | 143 +++++++++++++++++++++++--
 include/linux/iio/adc/ad_sigma_delta.h |  38 +++++++
 2 files changed, 171 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
index ebcd52526cac..261a9a6b45e1 100644
--- a/drivers/iio/adc/ad_sigma_delta.c
+++ b/drivers/iio/adc/ad_sigma_delta.c
@@ -6,6 +6,7 @@
  *  Author: Lars-Peter Clausen <lars@metafoo.de>
  */
 
+#include <linux/align.h>
 #include <linux/interrupt.h>
 #include <linux/device.h>
 #include <linux/kernel.h>
@@ -342,15 +343,49 @@ EXPORT_SYMBOL_NS_GPL(ad_sigma_delta_single_conversion, IIO_AD_SIGMA_DELTA);
 static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
 {
 	struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
+	unsigned int i, slot, samples_buf_size;
 	unsigned int channel;
+	uint8_t *samples_buf;
 	int ret;
 
-	channel = find_first_bit(indio_dev->active_scan_mask,
-				 indio_dev->masklength);
-	ret = ad_sigma_delta_set_channel(sigma_delta,
-		indio_dev->channels[channel].address);
-	if (ret)
-		return ret;
+	if (sigma_delta->num_slots == 1) {
+		channel = find_first_bit(indio_dev->active_scan_mask,
+					 indio_dev->masklength);
+		ret = ad_sigma_delta_set_channel(sigma_delta,
+						 indio_dev->channels[channel].address);
+		if (ret)
+			return ret;
+		slot = 1;
+	} else {
+		/*
+		 * At this point update_scan_mode already enabled the required channels.
+		 * For sigma-delta sequencer drivers with multiple slots, an update_scan_mode
+		 * implementation is mandatory.
+		 */
+		slot = 0;
+		for_each_set_bit(i, indio_dev->active_scan_mask, indio_dev->masklength) {
+			sigma_delta->slots[slot] = indio_dev->channels[i].address;
+			slot++;
+		}
+	}
+
+	sigma_delta->active_slots = slot;
+	sigma_delta->current_slot = 0;
+
+	if (sigma_delta->active_slots > 1) {
+		ret = ad_sigma_delta_append_status(sigma_delta, true);
+		if (ret)
+			return ret;
+	}
+
+	samples_buf_size = ALIGN(slot * indio_dev->channels[0].scan_type.storagebits, 8);
+	samples_buf_size += sizeof(int64_t);
+	samples_buf = devm_krealloc(&sigma_delta->spi->dev, sigma_delta->samples_buf,
+				    samples_buf_size, GFP_KERNEL);
+	if (!samples_buf)
+		return -ENOMEM;
+
+	sigma_delta->samples_buf = samples_buf;
 
 	spi_bus_lock(sigma_delta->spi->master);
 	sigma_delta->bus_locked = true;
@@ -386,6 +421,10 @@ static int ad_sd_buffer_postdisable(struct iio_dev *indio_dev)
 	sigma_delta->keep_cs_asserted = false;
 	ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
 
+	if (sigma_delta->status_appended)
+		ad_sigma_delta_append_status(sigma_delta, false);
+
+	ad_sigma_delta_disable_all(sigma_delta);
 	sigma_delta->bus_locked = false;
 	return spi_bus_unlock(sigma_delta->spi->master);
 }
@@ -396,6 +435,10 @@ static irqreturn_t ad_sd_trigger_handler(int irq, void *p)
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
 	uint8_t *data = sigma_delta->rx_buf;
+	unsigned int transfer_size;
+	unsigned int sample_size;
+	unsigned int sample_pos;
+	unsigned int status_pos;
 	unsigned int reg_size;
 	unsigned int data_reg;
 
@@ -408,21 +451,69 @@ static irqreturn_t ad_sd_trigger_handler(int irq, void *p)
 	else
 		data_reg = AD_SD_REG_DATA;
 
+	/* Status word will be appended to the sample during transfer */
+	if (sigma_delta->status_appended)
+		transfer_size = reg_size + 1;
+	else
+		transfer_size = reg_size;
+
 	switch (reg_size) {
 	case 4:
 	case 2:
 	case 1:
-		ad_sd_read_reg_raw(sigma_delta, data_reg, reg_size, &data[0]);
+		status_pos = reg_size;
+		ad_sd_read_reg_raw(sigma_delta, data_reg, transfer_size, &data[0]);
 		break;
 	case 3:
+		/*
+		 * Data array after transfer will look like (if status is appended):
+		 * data[] = { [0][sample][sample][sample][status] }
+		 * Keeping the first byte 0 shifts the status postion by 1 byte to the right.
+		 */
+		status_pos = reg_size + 1;
+
 		/* We store 24 bit samples in a 32 bit word. Keep the upper
 		 * byte set to zero. */
-		ad_sd_read_reg_raw(sigma_delta, data_reg, reg_size, &data[1]);
+		ad_sd_read_reg_raw(sigma_delta, data_reg, transfer_size, &data[1]);
 		break;
 	}
 
-	iio_push_to_buffers_with_timestamp(indio_dev, data, pf->timestamp);
+	/*
+	 * For devices sampling only one channel at
+	 * once, there is no need for sample number tracking.
+	 */
+	if (sigma_delta->active_slots == 1) {
+		iio_push_to_buffers_with_timestamp(indio_dev, data, pf->timestamp);
+		goto irq_handled;
+	}
+
+	if (sigma_delta->status_appended) {
+		u8 converted_channel;
+
+		converted_channel = data[status_pos] & sigma_delta->info->status_ch_mask;
+		if (converted_channel != sigma_delta->slots[sigma_delta->current_slot]) {
+			/*
+			 * Desync occurred during continuous sampling of multiple channels.
+			 * Drop this incomplete sample and start from first channel again.
+			 */
+
+			sigma_delta->current_slot = 0;
+			goto irq_handled;
+		}
+	}
+
+	sample_size = indio_dev->channels[0].scan_type.storagebits / 8;
+	sample_pos = sample_size * sigma_delta->current_slot;
+	memcpy(&sigma_delta->samples_buf[sample_pos], data, sample_size);
+	sigma_delta->current_slot++;
 
+	if (sigma_delta->current_slot == sigma_delta->active_slots) {
+		sigma_delta->current_slot = 0;
+		iio_push_to_buffers_with_timestamp(indio_dev, sigma_delta->samples_buf,
+						   pf->timestamp);
+	}
+
+irq_handled:
 	iio_trigger_notify_done(indio_dev->trig);
 	sigma_delta->irq_dis = false;
 	enable_irq(sigma_delta->spi->irq);
@@ -430,10 +521,17 @@ static irqreturn_t ad_sd_trigger_handler(int irq, void *p)
 	return IRQ_HANDLED;
 }
 
+static bool ad_sd_validate_scan_mask(struct iio_dev *indio_dev, const unsigned long *mask)
+{
+	struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
+
+	return bitmap_weight(mask, indio_dev->masklength) <= sigma_delta->num_slots;
+}
+
 static const struct iio_buffer_setup_ops ad_sd_buffer_setup_ops = {
 	.postenable = &ad_sd_buffer_postenable,
 	.postdisable = &ad_sd_buffer_postdisable,
-	.validate_scan_mask = &iio_validate_scan_mask_onehot,
+	.validate_scan_mask = &ad_sd_validate_scan_mask,
 };
 
 static irqreturn_t ad_sd_data_rdy_trig_poll(int irq, void *private)
@@ -513,8 +611,14 @@ static int devm_ad_sd_probe_trigger(struct device *dev, struct iio_dev *indio_de
  */
 int devm_ad_sd_setup_buffer_and_trigger(struct device *dev, struct iio_dev *indio_dev)
 {
+	struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
 	int ret;
 
+	sigma_delta->slots = devm_kcalloc(dev, sigma_delta->num_slots,
+					  sizeof(*sigma_delta->slots), GFP_KERNEL);
+	if (!sigma_delta->slots)
+		return -ENOMEM;
+
 	ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
 					      &iio_pollfunc_store_time,
 					      &ad_sd_trigger_handler,
@@ -541,6 +645,25 @@ int ad_sd_init(struct ad_sigma_delta *sigma_delta, struct iio_dev *indio_dev,
 {
 	sigma_delta->spi = spi;
 	sigma_delta->info = info;
+
+	/* If the field is unset in ad_sigma_delta_info, asume there can only be 1 slot. */
+	if (!info->num_slots)
+		sigma_delta->num_slots = 1;
+	else
+		sigma_delta->num_slots = info->num_slots;
+
+	if (sigma_delta->num_slots > 1) {
+		if (!indio_dev->info->update_scan_mode) {
+			dev_err(&spi->dev, "iio_dev lacks update_scan_mode().\n");
+			return -EINVAL;
+		}
+
+		if (!info->disable_all) {
+			dev_err(&spi->dev, "ad_sigma_delta_info lacks disable_all().\n");
+			return -EINVAL;
+		}
+	}
+
 	iio_device_set_drvdata(indio_dev, sigma_delta);
 
 	return 0;
diff --git a/include/linux/iio/adc/ad_sigma_delta.h b/include/linux/iio/adc/ad_sigma_delta.h
index c525fd51652f..7852f6c9a714 100644
--- a/include/linux/iio/adc/ad_sigma_delta.h
+++ b/include/linux/iio/adc/ad_sigma_delta.h
@@ -32,26 +32,34 @@ struct iio_dev;
 /**
  * struct ad_sigma_delta_info - Sigma Delta driver specific callbacks and options
  * @set_channel: Will be called to select the current channel, may be NULL.
+ * @append_status: Will be called to enable status append at the end of the sample, may be NULL.
  * @set_mode: Will be called to select the current mode, may be NULL.
+ * @disable_all: Will be called to disable all channels, may be NULL.
  * @postprocess_sample: Is called for each sampled data word, can be used to
  *		modify or drop the sample data, it, may be NULL.
  * @has_registers: true if the device has writable and readable registers, false
  *		if there is just one read-only sample data shift register.
  * @addr_shift: Shift of the register address in the communications register.
  * @read_mask: Mask for the communications register having the read bit set.
+ * @status_ch_mask: Mask for the channel number stored in status register.
  * @data_reg: Address of the data register, if 0 the default address of 0x3 will
  *   be used.
  * @irq_flags: flags for the interrupt used by the triggered buffer
+ * @num_slots: Number of sequencer slots
  */
 struct ad_sigma_delta_info {
 	int (*set_channel)(struct ad_sigma_delta *, unsigned int channel);
+	int (*append_status)(struct ad_sigma_delta *, bool append);
 	int (*set_mode)(struct ad_sigma_delta *, enum ad_sigma_delta_mode mode);
+	int (*disable_all)(struct ad_sigma_delta *);
 	int (*postprocess_sample)(struct ad_sigma_delta *, unsigned int raw_sample);
 	bool has_registers;
 	unsigned int addr_shift;
 	unsigned int read_mask;
+	unsigned int status_ch_mask;
 	unsigned int data_reg;
 	unsigned long irq_flags;
+	unsigned int num_slots;
 };
 
 /**
@@ -76,6 +84,13 @@ struct ad_sigma_delta {
 	uint8_t			comm;
 
 	const struct ad_sigma_delta_info *info;
+	unsigned int		active_slots;
+	unsigned int		current_slot;
+	unsigned int		num_slots;
+	bool			status_appended;
+	/* map slots to channels in order to know what to expect from devices */
+	unsigned int		*slots;
+	uint8_t			*samples_buf;
 
 	/*
 	 * DMA (thus cache coherency maintenance) requires the
@@ -97,6 +112,29 @@ static inline int ad_sigma_delta_set_channel(struct ad_sigma_delta *sd,
 	return 0;
 }
 
+static inline int ad_sigma_delta_append_status(struct ad_sigma_delta *sd, bool append)
+{
+	int ret;
+
+	if (sd->info->append_status) {
+		ret = sd->info->append_status(sd, append);
+		if (ret < 0)
+			return ret;
+
+		sd->status_appended = append;
+	}
+
+	return 0;
+}
+
+static inline int ad_sigma_delta_disable_all(struct ad_sigma_delta *sd)
+{
+	if (sd->info->disable_all)
+		return sd->info->disable_all(sd);
+
+	return 0;
+}
+
 static inline int ad_sigma_delta_set_mode(struct ad_sigma_delta *sd,
 	unsigned int mode)
 {
-- 
2.25.1

[PATCH v3 5/6] iio: adc: ad7124: add sequencer support

[alexandru.tachici]

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

Add sequencer support for AD7124.

Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
---
 drivers/iio/adc/ad7124.c | 74 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 65 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index 428ec3e257d7..e900e34e959a 100644
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -43,6 +43,8 @@
 #define AD7124_STATUS_POR_FLAG_MSK	BIT(4)
 
 /* AD7124_ADC_CONTROL */
+#define AD7124_ADC_STATUS_EN_MSK	BIT(10)
+#define AD7124_ADC_STATUS_EN(x)		FIELD_PREP(AD7124_ADC_STATUS_EN_MSK, x)
 #define AD7124_ADC_CTRL_REF_EN_MSK	BIT(8)
 #define AD7124_ADC_CTRL_REF_EN(x)	FIELD_PREP(AD7124_ADC_CTRL_REF_EN_MSK, x)
 #define AD7124_ADC_CTRL_PWR_MSK	GENMASK(7, 6)
@@ -500,26 +502,70 @@ static int ad7124_prepare_read(struct ad7124_state *st, int address)
 	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);
+
+	return ad7124_prepare_read(st, channel);
+}
+
 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);
+	ret = __ad7124_set_channel(sd, channel);
 	mutex_unlock(&st->cfgs_lock);
 
 	return ret;
 }
 
+static int ad7124_append_status(struct ad_sigma_delta *sd, bool append)
+{
+	struct ad7124_state *st = container_of(sd, struct ad7124_state, sd);
+	unsigned int adc_control = st->adc_control;
+	int ret;
+
+	adc_control &= ~AD7124_ADC_STATUS_EN_MSK;
+	adc_control |= AD7124_ADC_STATUS_EN(append);
+
+	ret = ad_sd_write_reg(&st->sd, AD7124_ADC_CONTROL, 2, adc_control);
+	if (ret < 0)
+		return ret;
+
+	st->adc_control = adc_control;
+
+	return 0;
+}
+
+static int ad7124_disable_all(struct ad_sigma_delta *sd)
+{
+	struct ad7124_state *st = container_of(sd, struct ad7124_state, sd);
+	int ret;
+	int i;
+
+	for (i = 0; i < st->num_channels; i++) {
+		ret = ad7124_spi_write_mask(st, AD7124_CHANNEL(i), AD7124_CHANNEL_EN_MSK, 0, 2);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
 static const struct ad_sigma_delta_info ad7124_sigma_delta_info = {
 	.set_channel = ad7124_set_channel,
+	.append_status = ad7124_append_status,
+	.disable_all = ad7124_disable_all,
 	.set_mode = ad7124_set_mode,
 	.has_registers = true,
 	.addr_shift = 0,
 	.read_mask = BIT(6),
+	.status_ch_mask = GENMASK(3, 0),
 	.data_reg = AD7124_DATA,
-	.irq_flags = IRQF_TRIGGER_FALLING
+	.num_slots = 8,
+	.irq_flags = IRQF_TRIGGER_FALLING,
 };
 
 static int ad7124_read_raw(struct iio_dev *indio_dev,
@@ -677,15 +723,23 @@ static int ad7124_update_scan_mode(struct iio_dev *indio_dev,
 	int ret;
 	int i;
 
+	mutex_lock(&st->cfgs_lock);
 	for (i = 0; i < st->num_channels; i++) {
 		bit_set = test_bit(i, scan_mask);
-		ret = ad7124_spi_write_mask(st, AD7124_CHANNEL(i),
-					    AD7124_CHANNEL_EN_MSK,
-					    AD7124_CHANNEL_EN(bit_set),
-					    2);
-		if (ret < 0)
+		if (bit_set)
+			ret = __ad7124_set_channel(&st->sd, i);
+		else
+			ret = ad7124_spi_write_mask(st, AD7124_CHANNEL(i), AD7124_CHANNEL_EN_MSK,
+						    0, 2);
+		if (ret < 0) {
+			mutex_unlock(&st->cfgs_lock);
+
 			return ret;
+		}
 	}
+
+	mutex_unlock(&st->cfgs_lock);
+
 	return 0;
 }
 
@@ -906,12 +960,14 @@ static int ad7124_probe(struct spi_device *spi)
 
 	st->chip_info = info;
 
-	ad_sd_init(&st->sd, indio_dev, spi, &ad7124_sigma_delta_info);
-
 	indio_dev->name = st->chip_info->name;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->info = &ad7124_info;
 
+	ret = ad_sd_init(&st->sd, indio_dev, spi, &ad7124_sigma_delta_info);
+	if (ret < 0)
+		return ret;
+
 	ret = ad7124_of_parse_channel_config(indio_dev, spi->dev.of_node);
 	if (ret < 0)
 		return ret;
-- 
2.25.1

[PATCH v3 6/6] iio: adc: ad7192: add sequencer support

[alexandru.tachici]

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

Add sequencer support for AD7192.

Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
---
 drivers/iio/adc/ad7192.c | 42 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ad7192.c b/drivers/iio/adc/ad7192.c
index 4c004af4749f..ba3c82f33d74 100644
--- a/drivers/iio/adc/ad7192.c
+++ b/drivers/iio/adc/ad7192.c
@@ -58,7 +58,8 @@
 /* Mode Register Bit Designations (AD7192_REG_MODE) */
 #define AD7192_MODE_SEL(x)	(((x) & 0x7) << 21) /* Operation Mode Select */
 #define AD7192_MODE_SEL_MASK	(0x7 << 21) /* Operation Mode Select Mask */
-#define AD7192_MODE_DAT_STA	BIT(20) /* Status Register transmission */
+#define AD7192_MODE_STA(x)	(((x) & 0x1) << 20) /* Status Register transmission */
+#define AD7192_MODE_STA_MASK	BIT(20) /* Status Register transmission Mask */
 #define AD7192_MODE_CLKSRC(x)	(((x) & 0x3) << 18) /* Clock Source Select */
 #define AD7192_MODE_SINC3	BIT(15) /* SINC3 Filter Select */
 #define AD7192_MODE_ACX		BIT(14) /* AC excitation enable(AD7195 only)*/
@@ -288,12 +289,51 @@ static int ad7192_set_mode(struct ad_sigma_delta *sd,
 	return ad_sd_write_reg(&st->sd, AD7192_REG_MODE, 3, st->mode);
 }
 
+static int ad7192_append_status(struct ad_sigma_delta *sd, bool append)
+{
+	struct ad7192_state *st = ad_sigma_delta_to_ad7192(sd);
+	unsigned int mode = st->mode;
+	int ret;
+
+	mode &= ~AD7192_MODE_STA_MASK;
+	mode |= AD7192_MODE_STA(append);
+
+	ret = ad_sd_write_reg(&st->sd, AD7192_REG_MODE, 3, mode);
+	if (ret < 0)
+		return ret;
+
+	st->mode = mode;
+
+	return 0;
+}
+
+static int ad7192_disable_all(struct ad_sigma_delta *sd)
+{
+	struct ad7192_state *st = ad_sigma_delta_to_ad7192(sd);
+	u32 conf = st->conf;
+	int ret;
+
+	conf &= ~AD7192_CONF_CHAN_MASK;
+
+	ret = ad_sd_write_reg(&st->sd, AD7192_REG_CONF, 3, conf);
+	if (ret < 0)
+		return ret;
+
+	st->conf = conf;
+
+	return 0;
+}
+
 static const struct ad_sigma_delta_info ad7192_sigma_delta_info = {
 	.set_channel = ad7192_set_channel,
+	.append_status = ad7192_append_status,
+	.disable_all = ad7192_disable_all,
 	.set_mode = ad7192_set_mode,
 	.has_registers = true,
 	.addr_shift = 3,
 	.read_mask = BIT(6),
+	.status_ch_mask = GENMASK(3, 0),
+	.num_slots = 4,
 	.irq_flags = IRQF_TRIGGER_FALLING,
 };
 
-- 
2.25.1

Re: [PATCH v3 0/6] iio: adc: ad_sigma_delta: Add sequencer support

[Jonathan Cameron]

On Tue, 22 Mar 2022 12:50:23 +0200
<alexandru.tachici@analog.com> wrote:

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

Hi Alexandru,

I just took another look at this and I'm happy with it.
Will leave it on list for a few more days for others to
take a look though before I queue it up.

Thanks,

Jonathan

> 
> Some sigma-delta chips support sampling of multiple
> channels in continuous mode.
> 
> When the operating with more than one channel enabled,
> the channel sequencer cycles through the enabled channels
> in sequential order, from first channel to the last one.
> If a channel is disabled, it is skipped by the sequencer.
> 
> If more than one channel is used in continuous mode,
> instruct the device to append the status to the SPI transfer
> (1 extra byte) every time we receive a sample.
> All sigma-delta chips possessing a sampling sequencer have
> this ability. Inside the status register there will be
> the number of the converted channel. In this way, even
> if the CPU won't keep up with the sampling rate, it won't
> send to userspace wrong channel samples.
> 
> 1. Removed the 1 byte .shift from channel spec in AD7124,
> it confuses userspace apps (no need to shift right).
> 
> 2. Add update_scan_mode to AD7124, it is required in order
> to enable/disable multiple channels at once
> 
> 3. Add update_scan_mode to AD7192, it is required in order
> to enable/disable multiple channels at once
> 
> 4. Add sequencer support for sigma_delta library.
> 
> 5. Add sigma_delta_info values and callbacks for sequencer
> support in AD7124.
> 
> 6. Add sigma_delta_info values and callbacks for sequencer
> support in AD7192.
> 
> Alexandru Tachici (5):
>   iio: adc: ad7124: Remove shift from scan_type
>   iio: adc: ad7124: Add update_scan_mode
>   iio: adc: ad7192: Add update_scan_mode
>   iio: adc: ad7124: add sequencer support
>   iio: adc: ad7192: add sequencer support
> 
> Lars-Peter Clausen (1):
>   iio: adc: ad_sigma_delta: Add sequencer support
> 
> Changelog V2 -> V3:
>   - ad_sd_buffer_postenable(), aligned (slot * storagebits) to 8 bytes
>   - devm_krealloc instead of krealloc for samples_buf in ad_sd_buffer_postenable()
>   - in ad_sigma_delta_append_status, check return value before setting .status_appended
>   - iio: adc: ad_sigma_delta: Add sequencer support: added explanations on
>   desynchronization checking and recovery
>   - in ad7124_append_status() modify st->adc_control after write has taken place without errors
>   - in ad7124_update_scan_mode() take cfg mutex only once instead of every time a
>   set_channel happens
>   - in ad7192_disable_all() modify st->conf after write taken place without errors
>   - in ad7192_append_status() modify st->mode after write taken place without errors
> 
>  drivers/iio/adc/ad7124.c               |  86 ++++++++++++++-
>  drivers/iio/adc/ad7192.c               |  64 ++++++++++-
>  drivers/iio/adc/ad_sigma_delta.c       | 143 +++++++++++++++++++++++--
>  include/linux/iio/adc/ad_sigma_delta.h |  38 +++++++
>  4 files changed, 315 insertions(+), 16 deletions(-)
> 
> --
> 2.25.1

Re: [PATCH v3 0/6] iio: adc: ad_sigma_delta: Add sequencer support

[Jonathan Cameron]

On Tue, 22 Mar 2022 21:30:02 +0000
Jonathan Cameron <Jonathan.Cameron@Huawei.com> wrote:

> On Tue, 22 Mar 2022 12:50:23 +0200
> <alexandru.tachici@analog.com> wrote:
> 
> > From: Alexandru Tachici <alexandru.tachici@analog.com>  
> 
> Hi Alexandru,
> 
> I just took another look at this and I'm happy with it.
> Will leave it on list for a few more days for others to
> take a look though before I queue it up.
> 
Applied to the togreg branch of iio.git though I won't push
that out, other than as testing, until I can rebase on rc1.

Thanks,

Jonathan
 
> Thanks,
> 
> Jonathan
> 
> > 
> > Some sigma-delta chips support sampling of multiple
> > channels in continuous mode.
> > 
> > When the operating with more than one channel enabled,
> > the channel sequencer cycles through the enabled channels
> > in sequential order, from first channel to the last one.
> > If a channel is disabled, it is skipped by the sequencer.
> > 
> > If more than one channel is used in continuous mode,
> > instruct the device to append the status to the SPI transfer
> > (1 extra byte) every time we receive a sample.
> > All sigma-delta chips possessing a sampling sequencer have
> > this ability. Inside the status register there will be
> > the number of the converted channel. In this way, even
> > if the CPU won't keep up with the sampling rate, it won't
> > send to userspace wrong channel samples.
> > 
> > 1. Removed the 1 byte .shift from channel spec in AD7124,
> > it confuses userspace apps (no need to shift right).
> > 
> > 2. Add update_scan_mode to AD7124, it is required in order
> > to enable/disable multiple channels at once
> > 
> > 3. Add update_scan_mode to AD7192, it is required in order
> > to enable/disable multiple channels at once
> > 
> > 4. Add sequencer support for sigma_delta library.
> > 
> > 5. Add sigma_delta_info values and callbacks for sequencer
> > support in AD7124.
> > 
> > 6. Add sigma_delta_info values and callbacks for sequencer
> > support in AD7192.
> > 
> > Alexandru Tachici (5):
> >   iio: adc: ad7124: Remove shift from scan_type
> >   iio: adc: ad7124: Add update_scan_mode
> >   iio: adc: ad7192: Add update_scan_mode
> >   iio: adc: ad7124: add sequencer support
> >   iio: adc: ad7192: add sequencer support
> > 
> > Lars-Peter Clausen (1):
> >   iio: adc: ad_sigma_delta: Add sequencer support
> > 
> > Changelog V2 -> V3:
> >   - ad_sd_buffer_postenable(), aligned (slot * storagebits) to 8 bytes
> >   - devm_krealloc instead of krealloc for samples_buf in ad_sd_buffer_postenable()
> >   - in ad_sigma_delta_append_status, check return value before setting .status_appended
> >   - iio: adc: ad_sigma_delta: Add sequencer support: added explanations on
> >   desynchronization checking and recovery
> >   - in ad7124_append_status() modify st->adc_control after write has taken place without errors
> >   - in ad7124_update_scan_mode() take cfg mutex only once instead of every time a
> >   set_channel happens
> >   - in ad7192_disable_all() modify st->conf after write taken place without errors
> >   - in ad7192_append_status() modify st->mode after write taken place without errors
> > 
> >  drivers/iio/adc/ad7124.c               |  86 ++++++++++++++-
> >  drivers/iio/adc/ad7192.c               |  64 ++++++++++-
> >  drivers/iio/adc/ad_sigma_delta.c       | 143 +++++++++++++++++++++++--
> >  include/linux/iio/adc/ad_sigma_delta.h |  38 +++++++
> >  4 files changed, 315 insertions(+), 16 deletions(-)
> > 
> > --
> > 2.25.1  
>