[PATCH v6 0/4] Add IIO backend support for AD7779

[PATCH v6 0/4] Add IIO backend support for AD7779

[Ioana Risteiu]

  - Add axi_adc_num_lanes_set in the adi_axi_adc_ops structure to support
  setting number of lanes used by AXI ADC.
  - Add the generic io-backends property to the AD7779 binding to enable
  support for the IIO backend framework.
  - Add the adi,num-lanes property to set the number of lanes used by
  AD7779.
  - Move the initialization specific to communication without iio-backend
  into a separate setup function.
  - Add a new functionality to ad7779 driver that streams data through data
  output interface using IIO backend interface.

Ioana Risteiu (4):
  iio: adc: adi-axi-adc: add axi_adc_num_lanes_set
  dt-bindings: iio: adc: add IIO backend support
  iio: adc: extract setup function without backend
  iio: adc: update ad7779 to use IIO backend

 .../bindings/iio/adc/adi,ad7779.yaml          |  44 +++-
 drivers/iio/adc/ad7779.c                      | 192 ++++++++++++++----
 drivers/iio/adc/adi-axi-adc.c                 |   1 +
 3 files changed, 196 insertions(+), 41 deletions(-)

-- 
2.47.2

[PATCH v6 1/4] iio: adc: adi-axi-adc: add axi_adc_num_lanes_set

[Ioana Risteiu]

Assign num_lanes_set in the adi_axi_adc_ops to axi_adc_num_lanes_set()
to support setting number of lanes used by AXI ADC. This operation is
included in the generic structure because the number of lanes is a
configurable parameter of the generic AXI ADC IP core, not specific to
a device.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Ioana Risteiu <Ioana.Risteiu@analog.com>
---
no changes in v6.
 drivers/iio/adc/adi-axi-adc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
index 2d86bb0e08a7..20bb59c24acf 100644
--- a/drivers/iio/adc/adi-axi-adc.c
+++ b/drivers/iio/adc/adi-axi-adc.c
@@ -617,6 +617,7 @@ static const struct iio_backend_ops adi_axi_adc_ops = {
 	.chan_status = axi_adc_chan_status,
 	.interface_type_get = axi_adc_interface_type_get,
 	.oversampling_ratio_set = axi_adc_oversampling_ratio_set,
+	.num_lanes_set = axi_adc_num_lanes_set,
 	.debugfs_reg_access = iio_backend_debugfs_ptr(axi_adc_reg_access),
 	.debugfs_print_chan_status = iio_backend_debugfs_ptr(axi_adc_debugfs_print_chan_status),
 };
-- 
2.47.2

[PATCH v6 2/4] dt-bindings: iio: adc: add IIO backend support

[Ioana Risteiu]

Add the generic io-backends property to the AD7779 binding to enable
support for the IIO backend framework.

Also add the adi,num-lanes property to set the number of lanes used by
AD7779.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Ioana Risteiu <Ioana.Risteiu@analog.com>
---
no changes in v6.
 .../bindings/iio/adc/adi,ad7779.yaml          | 44 ++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7779.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7779.yaml
index 044f92f39cfa..ba3f7b2bd6cf 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7779.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7779.yaml
@@ -80,11 +80,36 @@ properties:
   reset-gpios:
     maxItems: 1
 
+  io-backends:
+    maxItems: 1
+
+  adi,num-lanes:
+    description:
+      Number of lanes on which the data is sent on the output when the data
+      output interface is used.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [1, 2, 4]
+    default: 4
+
 required:
   - compatible
   - reg
   - clocks
-  - interrupts
+
+allOf:
+  - if:
+      not:
+        required:
+          - io-backends
+    then:
+      properties:
+        adi,num-lanes: false
+
+oneOf:
+  - required:
+      - interrupts
+  - required:
+      - io-backends
 
 unevaluatedProperties: false
 
@@ -107,4 +132,21 @@ examples:
           clocks = <&adc_clk>;
         };
     };
+
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+          compatible = "adi,ad7779";
+          reg = <0>;
+          start-gpios = <&gpio0 87 GPIO_ACTIVE_LOW>;
+          reset-gpios = <&gpio0 93 GPIO_ACTIVE_LOW>;
+          clocks = <&adc_clk>;
+          io-backends = <&iio_backend>;
+          adi,num-lanes = <4>;
+        };
+    };
 ...
-- 
2.47.2

[PATCH v6 3/4] iio: adc: extract setup function without backend

[Ioana Risteiu]

Refactor probe function by moving the initialization specific to
communication without iio-backend into a separate setup function.

The purpose of this modification is better code organization. No
functional changes intended.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Ioana Risteiu <Ioana.Risteiu@analog.com>
---
changes in v6:
 - move channels and num_channels assignment together in ad7779_setup_without_backend()
 drivers/iio/adc/ad7779.c | 86 +++++++++++++++++++++-------------------
 1 file changed, 46 insertions(+), 40 deletions(-)

diff --git a/drivers/iio/adc/ad7779.c b/drivers/iio/adc/ad7779.c
index 845adc510239..4e6fa6370593 100644
--- a/drivers/iio/adc/ad7779.c
+++ b/drivers/iio/adc/ad7779.c
@@ -752,6 +752,51 @@ static int ad7779_conf(struct ad7779_state *st, struct gpio_desc *start_gpio)
 	return 0;
 }
 
+static int ad7779_setup_without_backend(struct ad7779_state *st, struct iio_dev *indio_dev)
+{
+	int ret;
+	struct device *dev = &st->spi->dev;
+
+	indio_dev->info = &ad7779_info;
+	indio_dev->channels = st->chip_info->channels;
+	indio_dev->num_channels = ARRAY_SIZE(ad7779_channels);
+
+	st->trig = devm_iio_trigger_alloc(dev, "%s-dev%d", indio_dev->name,
+					  iio_device_id(indio_dev));
+	if (!st->trig)
+		return -ENOMEM;
+
+	st->trig->ops = &ad7779_trigger_ops;
+
+	iio_trigger_set_drvdata(st->trig, st);
+
+	ret = devm_request_irq(dev, st->spi->irq, iio_trigger_generic_data_rdy_poll,
+			       IRQF_ONESHOT | IRQF_NO_AUTOEN, indio_dev->name,
+			       st->trig);
+	if (ret)
+		return dev_err_probe(dev, ret, "request IRQ %d failed\n",
+				     st->spi->irq);
+
+	ret = devm_iio_trigger_register(dev, st->trig);
+	if (ret)
+		return ret;
+
+	indio_dev->trig = iio_trigger_get(st->trig);
+
+	init_completion(&st->completion);
+
+	ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
+					      &iio_pollfunc_store_time,
+					      &ad7779_trigger_handler,
+					      &ad7779_buffer_setup_ops);
+	if (ret)
+		return ret;
+
+	return ad7779_spi_write_mask(st, AD7779_REG_DOUT_FORMAT,
+				     AD7779_DCLK_CLK_DIV_MSK,
+				     FIELD_PREP(AD7779_DCLK_CLK_DIV_MSK, 7));
+}
+
 static int ad7779_probe(struct spi_device *spi)
 {
 	struct iio_dev *indio_dev;
@@ -760,9 +805,6 @@ static int ad7779_probe(struct spi_device *spi)
 	struct device *dev = &spi->dev;
 	int ret = -EINVAL;
 
-	if (!spi->irq)
-		return dev_err_probe(dev, ret, "DRDY irq not present\n");
-
 	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
 	if (!indio_dev)
 		return -ENOMEM;
@@ -804,45 +846,9 @@ static int ad7779_probe(struct spi_device *spi)
 		return ret;
 
 	indio_dev->name = st->chip_info->name;
-	indio_dev->info = &ad7779_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
-	indio_dev->channels = st->chip_info->channels;
-	indio_dev->num_channels = ARRAY_SIZE(ad7779_channels);
-
-	st->trig = devm_iio_trigger_alloc(dev, "%s-dev%d", indio_dev->name,
-					  iio_device_id(indio_dev));
-	if (!st->trig)
-		return -ENOMEM;
 
-	st->trig->ops = &ad7779_trigger_ops;
-
-	iio_trigger_set_drvdata(st->trig, st);
-
-	ret = devm_request_irq(dev, spi->irq, iio_trigger_generic_data_rdy_poll,
-			       IRQF_ONESHOT | IRQF_NO_AUTOEN, indio_dev->name,
-			       st->trig);
-	if (ret)
-		return dev_err_probe(dev, ret, "request IRQ %d failed\n",
-				     st->spi->irq);
-
-	ret = devm_iio_trigger_register(dev, st->trig);
-	if (ret)
-		return ret;
-
-	indio_dev->trig = iio_trigger_get(st->trig);
-
-	init_completion(&st->completion);
-
-	ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
-					      &iio_pollfunc_store_time,
-					      &ad7779_trigger_handler,
-					      &ad7779_buffer_setup_ops);
-	if (ret)
-		return ret;
-
-	ret = ad7779_spi_write_mask(st, AD7779_REG_DOUT_FORMAT,
-				    AD7779_DCLK_CLK_DIV_MSK,
-				    FIELD_PREP(AD7779_DCLK_CLK_DIV_MSK, 7));
+	ret = ad7779_setup_without_backend(st, indio_dev);
 	if (ret)
 		return ret;
 
-- 
2.47.2

[PATCH v6 4/4] iio: adc: update ad7779 to use IIO backend

[Ioana Risteiu]

Add a new functionality to ad7779 driver that streams data through data
output interface using IIO backend interface.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Ioana Risteiu <Ioana.Risteiu@analog.com>
---
changes in v6:
 - fix indentation
 - remove ad7779_data_lines enum
 - move channels and num_channels assignment together in ad7779_setup_channels()
 drivers/iio/adc/ad7779.c | 108 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 107 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ad7779.c b/drivers/iio/adc/ad7779.c
index 4e6fa6370593..aac5049c9a07 100644
--- a/drivers/iio/adc/ad7779.c
+++ b/drivers/iio/adc/ad7779.c
@@ -25,6 +25,7 @@
 #include <linux/units.h>
 
 #include <linux/iio/iio.h>
+#include <linux/iio/backend.h>
 #include <linux/iio/buffer.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/trigger.h>
@@ -145,6 +146,7 @@ struct ad7779_state {
 	struct completion completion;
 	unsigned int sampling_freq;
 	enum ad7779_filter filter_enabled;
+	struct iio_backend *back;
 	/*
 	 * DMA (thus cache coherency maintenance) requires the
 	 * transfer buffers to live in their own cache lines.
@@ -630,12 +632,38 @@ static int ad7779_reset(struct iio_dev *indio_dev, struct gpio_desc *reset_gpio)
 	return ret;
 }
 
+static int ad7779_update_scan_mode(struct iio_dev *indio_dev,
+				   const unsigned long *scan_mask)
+{
+	struct ad7779_state *st = iio_priv(indio_dev);
+	unsigned int c;
+	int ret;
+
+	for (c = 0; c < AD7779_NUM_CHANNELS; c++) {
+		if (test_bit(c, scan_mask))
+			ret = iio_backend_chan_enable(st->back, c);
+		else
+			ret = iio_backend_chan_disable(st->back, c);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 static const struct iio_info ad7779_info = {
 	.read_raw = ad7779_read_raw,
 	.write_raw = ad7779_write_raw,
 	.debugfs_reg_access = &ad7779_reg_access,
 };
 
+static const struct iio_info ad7779_info_data = {
+	.read_raw = ad7779_read_raw,
+	.write_raw = ad7779_write_raw,
+	.debugfs_reg_access = &ad7779_reg_access,
+	.update_scan_mode = &ad7779_update_scan_mode,
+};
+
 static const struct iio_enum ad7779_filter_enum = {
 	.items = ad7779_filter_type,
 	.num_items = ARRAY_SIZE(ad7779_filter_type),
@@ -752,6 +780,47 @@ static int ad7779_conf(struct ad7779_state *st, struct gpio_desc *start_gpio)
 	return 0;
 }
 
+static int ad7779_set_data_lines(struct iio_dev *indio_dev, u32 num_lanes)
+{
+	struct ad7779_state *st = iio_priv(indio_dev);
+	int ret;
+
+	if (num_lanes != 1 && num_lanes != 2 && num_lanes != 4)
+		return -EINVAL;
+
+	ret = ad7779_set_sampling_frequency(st, num_lanes * AD7779_DEFAULT_SAMPLING_1LINE);
+	if (ret)
+		return ret;
+
+	ret = iio_backend_num_lanes_set(st->back, num_lanes);
+	if (ret)
+		return ret;
+
+	return ad7779_spi_write_mask(st, AD7779_REG_DOUT_FORMAT,
+				     AD7779_DOUT_FORMAT_MSK,
+				     FIELD_PREP(AD7779_DOUT_FORMAT_MSK, 2 - ilog2(num_lanes)));
+}
+
+static int ad7779_setup_channels(struct iio_dev *indio_dev, const struct ad7779_state *st)
+{
+	struct iio_chan_spec *channels;
+	struct device *dev = &st->spi->dev;
+
+	channels = devm_kmemdup_array(dev, st->chip_info->channels,
+				      ARRAY_SIZE(ad7779_channels),
+				      sizeof(*channels), GFP_KERNEL);
+	if (!channels)
+		return -ENOMEM;
+
+	for (unsigned int i = 0; i < ARRAY_SIZE(ad7779_channels); i++)
+		channels[i].scan_type.endianness = IIO_CPU;
+
+	indio_dev->channels = channels;
+	indio_dev->num_channels = ARRAY_SIZE(ad7779_channels);
+
+	return 0;
+}
+
 static int ad7779_setup_without_backend(struct ad7779_state *st, struct iio_dev *indio_dev)
 {
 	int ret;
@@ -797,6 +866,39 @@ static int ad7779_setup_without_backend(struct ad7779_state *st, struct iio_dev
 				     FIELD_PREP(AD7779_DCLK_CLK_DIV_MSK, 7));
 }
 
+static int ad7779_setup_backend(struct ad7779_state *st, struct iio_dev *indio_dev)
+{
+	struct device *dev = &st->spi->dev;
+	int ret;
+	u32 num_lanes;
+
+	indio_dev->info = &ad7779_info_data;
+
+	ret = ad7779_setup_channels(indio_dev, st);
+	if (ret)
+		return ret;
+
+	st->back = devm_iio_backend_get(dev, NULL);
+	if (IS_ERR(st->back))
+		return dev_err_probe(dev, PTR_ERR(st->back),
+				     "failed to get iio backend");
+
+	ret = devm_iio_backend_request_buffer(dev, st->back, indio_dev);
+	if (ret)
+		return ret;
+
+	ret = devm_iio_backend_enable(dev, st->back);
+	if (ret)
+		return ret;
+
+	num_lanes = 4;
+	ret = device_property_read_u32(dev, "adi,num-lanes", &num_lanes);
+	if (ret && ret != -EINVAL)
+		return ret;
+
+	return ad7779_set_data_lines(indio_dev, num_lanes);
+}
+
 static int ad7779_probe(struct spi_device *spi)
 {
 	struct iio_dev *indio_dev;
@@ -848,7 +950,10 @@ static int ad7779_probe(struct spi_device *spi)
 	indio_dev->name = st->chip_info->name;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 
-	ret = ad7779_setup_without_backend(st, indio_dev);
+	if (device_property_present(dev, "io-backends"))
+		ret = ad7779_setup_backend(st, indio_dev);
+	else
+		ret = ad7779_setup_without_backend(st, indio_dev);
 	if (ret)
 		return ret;
 
@@ -942,3 +1047,4 @@ module_spi_driver(ad7779_driver);
 MODULE_AUTHOR("Ramona Alexandra Nechita <ramona.nechita@analog.com>");
 MODULE_DESCRIPTION("Analog Devices AD7779 ADC");
 MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_BACKEND");
-- 
2.47.2

Re: [PATCH v6 0/4] Add IIO backend support for AD7779

[David Lechner]

On 8/25/25 5:13 PM, Ioana Risteiu wrote:
>   - Add axi_adc_num_lanes_set in the adi_axi_adc_ops structure to support
>   setting number of lanes used by AXI ADC.
>   - Add the generic io-backends property to the AD7779 binding to enable
>   support for the IIO backend framework.
>   - Add the adi,num-lanes property to set the number of lanes used by
>   AD7779.
>   - Move the initialization specific to communication without iio-backend
>   into a separate setup function.
>   - Add a new functionality to ad7779 driver that streams data through data
>   output interface using IIO backend interface.

It is more helpful for the cover letter to contain a high-level
overview of why you want this series included in the kernel. We
can look at the individual patches to see what they are about, so
repeating that here isn't especially helpful.

For example, I would write the cover letter for this series like this:

The AD7779 ADC chip has a secondary data bus for high-speed data
transfers. To make use of this bus, it is connected to an FPGA IP
core [1] which is handled using the IIO backend framework. This IP
core connects to the data bus lines as well as the data ready signal
on the ADC. This interface can use 1, 2 or 4 lanes at a time.

This series extends the devicetree bindings to describe these wiring
configuration, extends the IIO backend framework to allow setting the
number of lanes that are being used, and extends the ad7779 driver to
allow using such a backend for reading data in buffered reads.

[1]: https://analogdevicesinc.github.io/hdl/projects/ad777x_fmcz/index.html

> 
> Ioana Risteiu (4):
>   iio: adc: adi-axi-adc: add axi_adc_num_lanes_set
>   dt-bindings: iio: adc: add IIO backend support
>   iio: adc: extract setup function without backend
>   iio: adc: update ad7779 to use IIO backend
> 
>  .../bindings/iio/adc/adi,ad7779.yaml          |  44 +++-
>  drivers/iio/adc/ad7779.c                      | 192 ++++++++++++++----
>  drivers/iio/adc/adi-axi-adc.c                 |   1 +
>  3 files changed, 196 insertions(+), 41 deletions(-)
> 

Please include a changelog of what was changed in each revision of
the series along with links to the previous revisions. Tools like
b4 can help automate this.

https://docs.kernel.org/6.16/process/submitting-patches.html

Re: [PATCH v6 0/4] Add IIO backend support for AD7779

[Jonathan Cameron]

On Tue, 26 Aug 2025 11:24:26 -0500
David Lechner <dlechner@baylibre.com> wrote:

> On 8/25/25 5:13 PM, Ioana Risteiu wrote:
> >   - Add axi_adc_num_lanes_set in the adi_axi_adc_ops structure to support
> >   setting number of lanes used by AXI ADC.
> >   - Add the generic io-backends property to the AD7779 binding to enable
> >   support for the IIO backend framework.
> >   - Add the adi,num-lanes property to set the number of lanes used by
> >   AD7779.
> >   - Move the initialization specific to communication without iio-backend
> >   into a separate setup function.
> >   - Add a new functionality to ad7779 driver that streams data through data
> >   output interface using IIO backend interface.  
> 
> It is more helpful for the cover letter to contain a high-level
> overview of why you want this series included in the kernel. We
> can look at the individual patches to see what they are about, so
> repeating that here isn't especially helpful.
> 
> For example, I would write the cover letter for this series like this:
> 
> The AD7779 ADC chip has a secondary data bus for high-speed data
> transfers. To make use of this bus, it is connected to an FPGA IP
> core [1] which is handled using the IIO backend framework. This IP
> core connects to the data bus lines as well as the data ready signal
> on the ADC. This interface can use 1, 2 or 4 lanes at a time.
> 
> This series extends the devicetree bindings to describe these wiring
> configuration, extends the IIO backend framework to allow setting the
> number of lanes that are being used, and extends the ad7779 driver to
> allow using such a backend for reading data in buffered reads.
> 
> [1]: https://analogdevicesinc.github.io/hdl/projects/ad777x_fmcz/index.html
> 
> > 
> > Ioana Risteiu (4):
> >   iio: adc: adi-axi-adc: add axi_adc_num_lanes_set
> >   dt-bindings: iio: adc: add IIO backend support
> >   iio: adc: extract setup function without backend
> >   iio: adc: update ad7779 to use IIO backend
> > 
> >  .../bindings/iio/adc/adi,ad7779.yaml          |  44 +++-
> >  drivers/iio/adc/ad7779.c                      | 192 ++++++++++++++----
> >  drivers/iio/adc/adi-axi-adc.c                 |   1 +
> >  3 files changed, 196 insertions(+), 41 deletions(-)
> >   
> 
> Please include a changelog of what was changed in each revision of
> the series along with links to the previous revisions. Tools like
> b4 can help automate this.
> 
> https://docs.kernel.org/6.16/process/submitting-patches.html
Whilst I fully agree with this, please keep the per patch change logs
as well as personally I find those more useful.  For those just
changes from previous version is fine.

Anyhow, other than this process stuff the series looks good to me
so applied to the togreg branch of iio.git and pushed out as testing.

Thanks,

Jonathan