[PATCH v2 0/8] iio: add new backend framework

[PATCH v2 0/8] iio: add new backend framework

[Nuno Sa via B4 Relay]

This series depends on [1] and it only build on top of it. The point is
to already speed up the reviewing of the framework. That obviously means
that all those pacthes were dropped in v2.

v1:
 https://lore.kernel.org/linux-iio/20231204144925.4fe9922f@jic23-huawei/T/#m222f5175273b81dbfe40b7f0daffcdc67d6cb8ff

Changes in v2:
 - Patch 1-2 and 5
   * new patches.
 - Patch 6:
   * Fixed some docs failures;
   * Fixed a legacy 'conv' name in one of the function parameters;
   * Added .request_buffer() and .free_buffer() ops;
   * Refactored the helper macros;
   * Added Olivier as Reviewer.
 - Patch 7:
   * Use new devm_iio_backend_request_buffer().
 - Patch 8:
   * Implement new .request_buffer() and .free_buffer() ops;

Also would like to mention that in v2 I'm experimenting in having the
DMA on the backend device (as discussed with David in v1). Does not look
to bad but as I said before, I'm not seeing a big issue if we end up
having the buffer allocation in the frontend.

For the bindings folks:

I'm introducing a new io-backends property in the ad9467 bindings but I'm
not sure this is the way to do it. Ideally that new property become a
generic schema and I'm guessing I should send a PULL to?

https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/iio/iio-consumer.yaml

(Jonathan, if you think that's not the right place, shout now :))

I'm also deprecating 'adi,adc-dev' as it is not relevant anymore. In the
driver code, we are actually breaking ABI but I'm taking a more
conservative approach in the bindings. Ideally I would also remove it in
the bindings :).
 

As requested here we have a small diagram that illustrated on e typical
usage of the new framework:

                                           -------------------------------------------------------
 ------------------                        | -----------         ------------      -------  FPGA |
 |     ADC        |------------------------| | AXI ADC |---------| DMA CORE |------| RAM |       |
 | (Frontend/IIO) | Serial Data (eg: LVDS) | |(backend)|---------|          |------|     |       |
 |                |------------------------| -----------         ------------      -------       |
 ------------------                        -------------------------------------------------------
 
The above is highly focused on ADI usecases. But one can see the idea...
The frontend is the real converter and is the one registering and
handling all the IIO interfaces. Such a device can then connect to a
backend device for further services/configurations. In the above
example, the backend device is an high speed core capable of handling
the high sample rate of these ADCs so that it can push that data further
in the pipeline (typically a DMA core) so the user can process the
samples with minimal losses.

Jonathan, I was also tempted in including the diagram in the source
file. Would that be a good idea?

[1]: https://lore.kernel.org/linux-iio/20231207-iio-backend-prep-v2-0-a4a33bc4d70e@analog.com

---
Nuno Sa (7):
      dt-bindings: adc: ad9467: document io-backend property
      dt-bindings: adc: axi-adc: deprecate 'adi,adc-dev'
      driver: core: allow modifying device_links flags
      iio: buffer-dmaengine: export buffer alloc and free functions
      iio: add the IIO backend framework
      iio: adc: ad9467: convert to backend framework
      iio: adc: adi-axi-adc: move to backend framework

Olivier Moysan (1):
      of: property: add device link support for io-backends

 .../devicetree/bindings/iio/adc/adi,ad9467.yaml    |   5 +
 .../devicetree/bindings/iio/adc/adi,axi-adc.yaml   |   4 +-
 MAINTAINERS                                        |   8 +
 drivers/base/core.c                                |  14 +-
 drivers/iio/Kconfig                                |   5 +
 drivers/iio/Makefile                               |   1 +
 drivers/iio/adc/Kconfig                            |   3 +-
 drivers/iio/adc/ad9467.c                           | 242 +++++++------
 drivers/iio/adc/adi-axi-adc.c                      | 379 +++++---------------
 drivers/iio/buffer/industrialio-buffer-dmaengine.c |   6 +-
 drivers/iio/industrialio-backend.c                 | 386 +++++++++++++++++++++
 drivers/of/property.c                              |   2 +
 include/linux/iio/adc/adi-axi-adc.h                |  68 ----
 include/linux/iio/backend.h                        |  68 ++++
 include/linux/iio/buffer-dmaengine.h               |   4 +-
 15 files changed, 727 insertions(+), 468 deletions(-)
---
base-commit: 330c0f834ccbdbe6a89da475cb1c56893f3a8363
change-id: 20231120-dev-iio-backend-d14b473a1d9f
--

Thanks!
- Nuno Sá

[PATCH v2 1/8] dt-bindings: adc: ad9467: document io-backend property

[Nuno Sa via B4 Relay]

From: Nuno Sa <nuno.sa@analog.com>

Add a new property to reference IIO backend devices.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
 Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml
index 7aa748d6b7a0..ae74249b4726 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml
@@ -44,6 +44,10 @@ properties:
       Pin that controls the powerdown mode of the device.
     maxItems: 1
 
+  io-backends:
+    description: Phandle to the IIO backend device.
+    $ref: /schemas/types.yaml#/definitions/phandle
+
   reset-gpios:
     description:
       Reset pin for the device.
@@ -68,6 +72,7 @@ examples:
             reg = <0>;
             clocks = <&adc_clk>;
             clock-names = "adc-clk";
+            io-backends = <&iio_backend>;
         };
     };
 ...

-- 
2.43.0

Re: [PATCH v2 1/8] dt-bindings: adc: ad9467: document io-backend property

[Krzysztof Kozlowski]

On 08/12/2023 16:14, Nuno Sa via B4 Relay wrote:
> From: Nuno Sa <nuno.sa@analog.com>
> 
> Add a new property to reference IIO backend devices.

This we can see. But why?

> 
> Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> ---
>  Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml
> index 7aa748d6b7a0..ae74249b4726 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml
> @@ -44,6 +44,10 @@ properties:
>        Pin that controls the powerdown mode of the device.
>      maxItems: 1
>  
> +  io-backends:
> +    description: Phandle to the IIO backend device.

Looks like standard property. Where is it defined? What is the meaning
(your description does not tell me anything more than property name and
its type)

> +    $ref: /schemas/types.yaml#/definitions/phandle
> +

Best regards,
Krzysztof

Re: [PATCH v2 1/8] dt-bindings: adc: ad9467: document io-backend property

[Nuno Sá]

On Fri, 2023-12-08 at 18:40 +0100, Krzysztof Kozlowski wrote:
> On 08/12/2023 16:14, Nuno Sa via B4 Relay wrote:
> > From: Nuno Sa <nuno.sa@analog.com>
> > 
> > Add a new property to reference IIO backend devices.
> 
> This we can see. But why?
> 
> > 
> > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > ---
> >  Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml
> > b/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml
> > index 7aa748d6b7a0..ae74249b4726 100644
> > --- a/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml
> > +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml
> > @@ -44,6 +44,10 @@ properties:
> >        Pin that controls the powerdown mode of the device.
> >      maxItems: 1
> >  
> > +  io-backends:
> > +    description: Phandle to the IIO backend device.
> 
> Looks like standard property. Where is it defined? What is the meaning
> (your description does not tell me anything more than property name and
> its type)

Yeah, Conor already gave me some feedback in the cover where I mention this property.
I'll improve on the description and send a PR for a generic schema.

Thanks!
- Nuno Sá

[PATCH v2 2/8] dt-bindings: adc: axi-adc: deprecate 'adi,adc-dev'

[Nuno Sa via B4 Relay]

From: Nuno Sa <nuno.sa@analog.com>

'adi,adc-dev' is now deprecated and must not be used anymore. Hence,
also remove it from being required.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
 Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml b/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml
index 9996dd93f84b..835b40063343 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml
@@ -39,12 +39,12 @@ properties:
     $ref: /schemas/types.yaml#/definitions/phandle
     description:
       A reference to a the actual ADC to which this FPGA ADC interfaces to.
+    deprecated: true
 
 required:
   - compatible
   - dmas
   - reg
-  - adi,adc-dev
 
 additionalProperties: false
 
@@ -55,7 +55,5 @@ examples:
         reg = <0x44a00000 0x10000>;
         dmas = <&rx_dma 0>;
         dma-names = "rx";
-
-        adi,adc-dev = <&spi_adc>;
     };
 ...

-- 
2.43.0

Re: [PATCH v2 2/8] dt-bindings: adc: axi-adc: deprecate 'adi,adc-dev'

[Krzysztof Kozlowski]

On 08/12/2023 16:14, Nuno Sa via B4 Relay wrote:
> From: Nuno Sa <nuno.sa@analog.com>
> 
> 'adi,adc-dev' is now deprecated and must not be used anymore. Hence,
> also remove it from being required.

Why did it become suddenly deprecated? Unfortunately the commit msg does
not tell me more, except copying the code...

If this is result of previous patch, then squash it.

Best regards,
Krzysztof

Re: [PATCH v2 2/8] dt-bindings: adc: axi-adc: deprecate 'adi,adc-dev'

[Nuno Sá]

On Fri, 2023-12-08 at 18:39 +0100, Krzysztof Kozlowski wrote:
> On 08/12/2023 16:14, Nuno Sa via B4 Relay wrote:
> > From: Nuno Sa <nuno.sa@analog.com>
> > 
> > 'adi,adc-dev' is now deprecated and must not be used anymore. Hence,
> > also remove it from being required.
> 
> Why did it become suddenly deprecated? Unfortunately the commit msg does
> not tell me more, except copying the code...
> 
> If this is result of previous patch, then squash it.
> 

This property will be deprecated by the generic property mentioned in the cover
(basically the property in patch 1).

I'll improve the commit message on why it's being deprecated. It has a lot to do with
the changes in the drivers and how we want to start handling these HW arrangements.
I'll try to explain it in a way that makes sense from a bindings point of view.

Thanks!
- Nuno Sá

[PATCH v2 3/8] driver: core: allow modifying device_links flags

[Nuno Sa via B4 Relay]

From: Nuno Sa <nuno.sa@analog.com>

If a device_link is previously created (eg: via
fw_devlink_create_devlink()) before the supplier + consumer are both
present and bound to their respective drivers, there's no way to set
DL_FLAG_AUTOREMOVE_CONSUMER anymore while one can still set
DL_FLAG_AUTOREMOVE_SUPPLIER. Hence, rework the flags checks to allow
for DL_FLAG_AUTOREMOVE_CONSUMER in the same way
DL_FLAG_AUTOREMOVE_SUPPLIER is done.

While at it, make sure that we are never left with
DL_FLAG_AUTOPROBE_CONSUMER set together with one of
DL_FLAG_AUTOREMOVE_CONSUMER or DL_FLAG_AUTOREMOVE_SUPPLIER.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
 drivers/base/core.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 67ba592afc77..fdbb5abc75d5 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -807,11 +807,15 @@ struct device_link *device_link_add(struct device *consumer,
 		 * update the existing link to stay around longer.
 		 */
 		if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER) {
-			if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
-				link->flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
-				link->flags |= DL_FLAG_AUTOREMOVE_SUPPLIER;
-			}
-		} else if (!(flags & DL_FLAG_AUTOREMOVE_CONSUMER)) {
+			link->flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
+			link->flags &= ~DL_FLAG_AUTOPROBE_CONSUMER;
+			link->flags |= DL_FLAG_AUTOREMOVE_SUPPLIER;
+
+		} else if (flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
+			link->flags &= ~DL_FLAG_AUTOREMOVE_SUPPLIER;
+			link->flags &= ~DL_FLAG_AUTOPROBE_CONSUMER;
+			link->flags |= DL_FLAG_AUTOREMOVE_CONSUMER;
+		} else {
 			link->flags &= ~(DL_FLAG_AUTOREMOVE_CONSUMER |
 					 DL_FLAG_AUTOREMOVE_SUPPLIER);
 		}

-- 
2.43.0

Re: [PATCH v2 3/8] driver: core: allow modifying device_links flags

[Jonathan Cameron]

On Fri, 08 Dec 2023 16:14:10 +0100
Nuno Sa via B4 Relay <devnull+nuno.sa.analog.com@kernel.org> wrote:

> From: Nuno Sa <nuno.sa@analog.com>
> 
> If a device_link is previously created (eg: via
> fw_devlink_create_devlink()) before the supplier + consumer are both
> present and bound to their respective drivers, there's no way to set
> DL_FLAG_AUTOREMOVE_CONSUMER anymore while one can still set
> DL_FLAG_AUTOREMOVE_SUPPLIER. Hence, rework the flags checks to allow
> for DL_FLAG_AUTOREMOVE_CONSUMER in the same way
> DL_FLAG_AUTOREMOVE_SUPPLIER is done.
> 
> While at it, make sure that we are never left with
> DL_FLAG_AUTOPROBE_CONSUMER set together with one of
> DL_FLAG_AUTOREMOVE_CONSUMER or DL_FLAG_AUTOREMOVE_SUPPLIER.
> 
> Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> ---
>  drivers/base/core.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 67ba592afc77..fdbb5abc75d5 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -807,11 +807,15 @@ struct device_link *device_link_add(struct device *consumer,
>  		 * update the existing link to stay around longer.
>  		 */
>  		if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER) {
> -			if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
> -				link->flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
> -				link->flags |= DL_FLAG_AUTOREMOVE_SUPPLIER;
> -			}
> -		} else if (!(flags & DL_FLAG_AUTOREMOVE_CONSUMER)) {
> +			link->flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
> +			link->flags &= ~DL_FLAG_AUTOPROBE_CONSUMER;
> +			link->flags |= DL_FLAG_AUTOREMOVE_SUPPLIER;
> +

Trivial but this blank line seems unwanted variation in formatting.

> +		} else if (flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
> +			link->flags &= ~DL_FLAG_AUTOREMOVE_SUPPLIER;
> +			link->flags &= ~DL_FLAG_AUTOPROBE_CONSUMER;
> +			link->flags |= DL_FLAG_AUTOREMOVE_CONSUMER;
> +		} else {
>  			link->flags &= ~(DL_FLAG_AUTOREMOVE_CONSUMER |
>  					 DL_FLAG_AUTOREMOVE_SUPPLIER);
>  		}
> 

[PATCH v2 4/8] of: property: add device link support for io-backends

[Nuno Sa via B4 Relay]

From: Olivier Moysan <olivier.moysan@foss.st.com>

Add support for creating device links out of more DT properties.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
 drivers/of/property.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/of/property.c b/drivers/of/property.c
index afdaefbd03f6..a4835447759f 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1244,6 +1244,7 @@ DEFINE_SIMPLE_PROP(interconnects, "interconnects", "#interconnect-cells")
 DEFINE_SIMPLE_PROP(iommus, "iommus", "#iommu-cells")
 DEFINE_SIMPLE_PROP(mboxes, "mboxes", "#mbox-cells")
 DEFINE_SIMPLE_PROP(io_channels, "io-channel", "#io-channel-cells")
+DEFINE_SIMPLE_PROP(io_backends, "io-backends", NULL)
 DEFINE_SIMPLE_PROP(interrupt_parent, "interrupt-parent", NULL)
 DEFINE_SIMPLE_PROP(dmas, "dmas", "#dma-cells")
 DEFINE_SIMPLE_PROP(power_domains, "power-domains", "#power-domain-cells")
@@ -1334,6 +1335,7 @@ static const struct supplier_bindings of_supplier_bindings[] = {
 	{ .parse_prop = parse_iommu_maps, .optional = true, },
 	{ .parse_prop = parse_mboxes, },
 	{ .parse_prop = parse_io_channels, },
+	{ .parse_prop = parse_io_backends, },
 	{ .parse_prop = parse_interrupt_parent, },
 	{ .parse_prop = parse_dmas, .optional = true, },
 	{ .parse_prop = parse_power_domains, },

-- 
2.43.0

[PATCH v2 5/8] iio: buffer-dmaengine: export buffer alloc and free functions

[Nuno Sa via B4 Relay]

From: Nuno Sa <nuno.sa@analog.com>

Export iio_dmaengine_buffer_free() and iio_dmaengine_buffer_alloc().
This is in preparation of introducing IIO backends support. This will
allow us to allocate a buffer and control it's lifetime from a device
different from the one holding the DMA firmware properties. Effectively,
in this case the struct device holding the firmware information about
the DMA channels is not the same as iio_dev->dev.parent (typical case).

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
 drivers/iio/buffer/industrialio-buffer-dmaengine.c | 6 ++++--
 include/linux/iio/buffer-dmaengine.h               | 4 +++-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
index 5f85ba38e6f6..5bf8c5eb1853 100644
--- a/drivers/iio/buffer/industrialio-buffer-dmaengine.c
+++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
@@ -159,7 +159,7 @@ static const struct iio_dev_attr *iio_dmaengine_buffer_attrs[] = {
  * Once done using the buffer iio_dmaengine_buffer_free() should be used to
  * release it.
  */
-static struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
+struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
 	const char *channel)
 {
 	struct dmaengine_buffer *dmaengine_buffer;
@@ -210,6 +210,7 @@ static struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
 	kfree(dmaengine_buffer);
 	return ERR_PTR(ret);
 }
+EXPORT_SYMBOL_GPL(iio_dmaengine_buffer_alloc);
 
 /**
  * iio_dmaengine_buffer_free() - Free dmaengine buffer
@@ -217,7 +218,7 @@ static struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
  *
  * Frees a buffer previously allocated with iio_dmaengine_buffer_alloc().
  */
-static void iio_dmaengine_buffer_free(struct iio_buffer *buffer)
+void iio_dmaengine_buffer_free(struct iio_buffer *buffer)
 {
 	struct dmaengine_buffer *dmaengine_buffer =
 		iio_buffer_to_dmaengine_buffer(buffer);
@@ -227,6 +228,7 @@ static void iio_dmaengine_buffer_free(struct iio_buffer *buffer)
 
 	iio_buffer_put(buffer);
 }
+EXPORT_SYMBOL_GPL(iio_dmaengine_buffer_free);
 
 static void __devm_iio_dmaengine_buffer_free(void *buffer)
 {
diff --git a/include/linux/iio/buffer-dmaengine.h b/include/linux/iio/buffer-dmaengine.h
index 5c355be89814..6c44da550b2c 100644
--- a/include/linux/iio/buffer-dmaengine.h
+++ b/include/linux/iio/buffer-dmaengine.h
@@ -10,8 +10,10 @@
 struct iio_dev;
 struct device;
 
+struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
+					      const char *channel);
+void iio_dmaengine_buffer_free(struct iio_buffer *buffer);
 int devm_iio_dmaengine_buffer_setup(struct device *dev,
 				    struct iio_dev *indio_dev,
 				    const char *channel);
-
 #endif

-- 
2.43.0

Re: [PATCH v2 5/8] iio: buffer-dmaengine: export buffer alloc and free functions

[Jonathan Cameron]

On Fri, 08 Dec 2023 16:14:12 +0100
Nuno Sa via B4 Relay <devnull+nuno.sa.analog.com@kernel.org> wrote:

> From: Nuno Sa <nuno.sa@analog.com>
> 
> Export iio_dmaengine_buffer_free() and iio_dmaengine_buffer_alloc().
> This is in preparation of introducing IIO backends support. This will
> allow us to allocate a buffer and control it's lifetime from a device
> different from the one holding the DMA firmware properties. Effectively,
> in this case the struct device holding the firmware information about
> the DMA channels is not the same as iio_dev->dev.parent (typical case).
> 
> Signed-off-by: Nuno Sa <nuno.sa@analog.com>

Probably a good idea to namespace these and existing exports related
to buffer-dmaengine whilst you are at it.

> ---
>  drivers/iio/buffer/industrialio-buffer-dmaengine.c | 6 ++++--
>  include/linux/iio/buffer-dmaengine.h               | 4 +++-
>  2 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
> index 5f85ba38e6f6..5bf8c5eb1853 100644
> --- a/drivers/iio/buffer/industrialio-buffer-dmaengine.c
> +++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
> @@ -159,7 +159,7 @@ static const struct iio_dev_attr *iio_dmaengine_buffer_attrs[] = {
>   * Once done using the buffer iio_dmaengine_buffer_free() should be used to
>   * release it.
>   */
> -static struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
> +struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
>  	const char *channel)
>  {
>  	struct dmaengine_buffer *dmaengine_buffer;
> @@ -210,6 +210,7 @@ static struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
>  	kfree(dmaengine_buffer);
>  	return ERR_PTR(ret);
>  }
> +EXPORT_SYMBOL_GPL(iio_dmaengine_buffer_alloc);
>  
>  /**
>   * iio_dmaengine_buffer_free() - Free dmaengine buffer
> @@ -217,7 +218,7 @@ static struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
>   *
>   * Frees a buffer previously allocated with iio_dmaengine_buffer_alloc().
>   */
> -static void iio_dmaengine_buffer_free(struct iio_buffer *buffer)
> +void iio_dmaengine_buffer_free(struct iio_buffer *buffer)
>  {
>  	struct dmaengine_buffer *dmaengine_buffer =
>  		iio_buffer_to_dmaengine_buffer(buffer);
> @@ -227,6 +228,7 @@ static void iio_dmaengine_buffer_free(struct iio_buffer *buffer)
>  
>  	iio_buffer_put(buffer);
>  }
> +EXPORT_SYMBOL_GPL(iio_dmaengine_buffer_free);
>  
>  static void __devm_iio_dmaengine_buffer_free(void *buffer)
>  {
> diff --git a/include/linux/iio/buffer-dmaengine.h b/include/linux/iio/buffer-dmaengine.h
> index 5c355be89814..6c44da550b2c 100644
> --- a/include/linux/iio/buffer-dmaengine.h
> +++ b/include/linux/iio/buffer-dmaengine.h
> @@ -10,8 +10,10 @@
>  struct iio_dev;
>  struct device;
>  
> +struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
> +					      const char *channel);
> +void iio_dmaengine_buffer_free(struct iio_buffer *buffer);
>  int devm_iio_dmaengine_buffer_setup(struct device *dev,
>  				    struct iio_dev *indio_dev,
>  				    const char *channel);
> -
Unrelated change.

>  #endif
> 

Re: [PATCH v2 5/8] iio: buffer-dmaengine: export buffer alloc and free functions

[Nuno Sá]

On Sun, 2023-12-10 at 14:24 +0000, Jonathan Cameron wrote:
> On Fri, 08 Dec 2023 16:14:12 +0100
> Nuno Sa via B4 Relay <devnull+nuno.sa.analog.com@kernel.org> wrote:
> 
> > From: Nuno Sa <nuno.sa@analog.com>
> > 
> > Export iio_dmaengine_buffer_free() and iio_dmaengine_buffer_alloc().
> > This is in preparation of introducing IIO backends support. This will
> > allow us to allocate a buffer and control it's lifetime from a device
> > different from the one holding the DMA firmware properties. Effectively,
> > in this case the struct device holding the firmware information about
> > the DMA channels is not the same as iio_dev->dev.parent (typical case).
> > 
> > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> 
> Probably a good idea to namespace these and existing exports related
> to buffer-dmaengine whilst you are at it.
> 

Will do that...

> 
- Nuno Sá

[PATCH v2 6/8] iio: add the IIO backend framework

[Nuno Sa via B4 Relay]

From: Nuno Sa <nuno.sa@analog.com>

This is a Framework to handle complex IIO aggregate devices.

The typical architecture is to have one device as the frontend device which
can be "linked" against one or multiple backend devices. All the IIO and
userspace interface is expected to be registers/managed by the frontend
device which will callback into the backends when needed (to get/set
some configuration that it does not directly control).

The basic framework interface is pretty simple:
 - Backends should register themselves with @devm_iio_backend_register()
 - Frontend devices should get backends with @devm_iio_backend_get()

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
 MAINTAINERS                        |   8 +
 drivers/iio/Kconfig                |   5 +
 drivers/iio/Makefile               |   1 +
 drivers/iio/industrialio-backend.c | 386 +++++++++++++++++++++++++++++++++++++
 include/linux/iio/backend.h        |  68 +++++++
 5 files changed, 468 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 1338e1176ea5..637ce907dcbf 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10320,6 +10320,14 @@ L:	linux-media@vger.kernel.org
 S:	Maintained
 F:	drivers/media/rc/iguanair.c
 
+IIO BACKEND FRAMEWORK
+M:	Nuno Sa <nuno.sa@analog.com>
+R:	Olivier Moysan <olivier.moysan@foss.st.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	drivers/iio/industrialio-backend.c
+F:	include/linux/iio/backend.h
+
 IIO DIGITAL POTENTIOMETER DAC
 M:	Peter Rosin <peda@axentia.se>
 L:	linux-iio@vger.kernel.org
diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index 52eb46ef84c1..451671112f73 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -71,6 +71,11 @@ config IIO_TRIGGERED_EVENT
 	help
 	  Provides helper functions for setting up triggered events.
 
+config IIO_BACKEND
+	tristate
+	help
+	  Framework to handle complex IIO aggregate devices.
+
 source "drivers/iio/accel/Kconfig"
 source "drivers/iio/adc/Kconfig"
 source "drivers/iio/addac/Kconfig"
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 9622347a1c1b..0ba0e1521ba4 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_IIO_GTS_HELPER) += industrialio-gts-helper.o
 obj-$(CONFIG_IIO_SW_DEVICE) += industrialio-sw-device.o
 obj-$(CONFIG_IIO_SW_TRIGGER) += industrialio-sw-trigger.o
 obj-$(CONFIG_IIO_TRIGGERED_EVENT) += industrialio-triggered-event.o
+obj-$(CONFIG_IIO_BACKEND) += industrialio-backend.o
 
 obj-y += accel/
 obj-y += adc/
diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
new file mode 100644
index 000000000000..3400b3b5a93b
--- /dev/null
+++ b/drivers/iio/industrialio-backend.c
@@ -0,0 +1,386 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Framework to handle complex IIO aggregate devices.
+ *
+ * The typical architecture is to have one device as the frontend device which
+ * can be "linked" against one or multiple backend devices. All the IIO and
+ * userspace interface is expected to be registers/managed by the frontend
+ * device which will callback into the backends when needed (to get/set some
+ * configuration that it does not directly control).
+ *
+ * The framework interface is pretty simple:
+ *   - Backends should register themselves with @devm_iio_backend_register()
+ *   - Frontend devices should get backends with @devm_iio_backend_get()
+ *
+ * Also to note that the primary target for this framework are converters like
+ * ADC/DACs so @iio_backend_ops will have some operations typical of converter
+ * devices. On top of that, this is "generic" for all IIO which means any kind
+ * of device can make use of the framework. That said, If the @iio_backend_ops
+ * struct begins to grow out of control, we can always refactor things so that
+ * the industrialio-backend.c is only left with the really generic stuff. Then,
+ * we can build on top of it depending on the needs.
+ *
+ * Copyright (C) 2023 Analog Devices Inc.
+ */
+#define pr_fmt(fmt) "iio-backend: " fmt
+
+#include <linux/cleanup.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/list.h>
+#include <linux/lockdep.h>
+#include <linux/kref.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+
+#include <linux/iio/backend.h>
+
+struct iio_backend {
+	struct list_head entry;
+	const struct iio_backend_ops *ops;
+	struct device *dev;
+	struct module *owner;
+	void *priv;
+	/*
+	 * mutex used to synchronize backend callback access with concurrent
+	 * calls to @iio_backend_unregister. The lock makes sure a device is
+	 * not unregistered while a callback is being run.
+	 */
+	struct mutex lock;
+	struct kref ref;
+};
+
+/*
+ * Helper struct for requesting buffers. Allows for multiple buffers per
+ * backend.
+ */
+struct iio_backend_buffer_pair {
+	struct iio_backend *back;
+	struct iio_buffer *buffer;
+};
+
+static LIST_HEAD(iio_back_list);
+static DEFINE_MUTEX(iio_back_lock);
+
+/*
+ * Helper macros to properly call backend ops. The main point for these macros
+ * is to properly lock the backend mutex on every call plus checking if the
+ * backend device is still around (by looking at the *ops pointer).
+ */
+
+#define iio_backend_check_op(back, op) ({ \
+	struct iio_backend *____back = back;				\
+	int ____ret = 0;						\
+									\
+	lockdep_assert_held(&____back->lock);				\
+	if (!____back->ops) {						\
+		pr_warn_once("Backend is no longer available\n");	\
+		____ret = -ENODEV;					\
+	} else if (!____back->ops->op) {				\
+		____ret = -EOPNOTSUPP;					\
+	}								\
+									\
+	____ret;								\
+})
+
+#define iio_backend_op_call(back, op, args...) ({		\
+	struct iio_backend *__back = back;			\
+	int __ret;						\
+								\
+	guard(mutex)(&__back->lock);				\
+	__ret = iio_backend_check_op(__back, op);		\
+	if (!__ret)						\
+		__ret = __back->ops->op(__back, ##args);	\
+								\
+	__ret;							\
+})
+
+#define iio_backend_ptr_op_call(back, op, args...) ({		\
+	struct iio_backend *__back = back;			\
+	void *ptr_err;						\
+	int __ret;						\
+								\
+	guard(mutex)(&__back->lock);				\
+	__ret = iio_backend_check_op(__back, op);		\
+	if (__ret)						\
+		ptr_err = ERR_PTR(__ret);			\
+	else							\
+		ptr_err = __back->ops->op(__back, ##args);	\
+								\
+	ptr_err;						\
+})
+
+#define iio_backend_void_op_call(back, op, args...) {		\
+	struct iio_backend *__back = back;			\
+	int __ret;						\
+								\
+	guard(mutex)(&__back->lock);				\
+	__ret = iio_backend_check_op(__back, op);		\
+	if (!__ret)						\
+		__back->ops->op(__back, ##args);		\
+}
+
+/**
+ * iio_backend_chan_enable - Enable a backend channel.
+ * @back:	Backend device.
+ * @chan:	Channel number.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_chan_enable(struct iio_backend *back, unsigned int chan)
+{
+	return iio_backend_op_call(back, chan_enable, chan);
+}
+EXPORT_SYMBOL_GPL(iio_backend_chan_enable);
+
+/**
+ * iio_backend_chan_disable - Disable a backend channel.
+ * @back:	Backend device.
+ * @chan:	Channel number.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_chan_disable(struct iio_backend *back, unsigned int chan)
+{
+	return iio_backend_op_call(back, chan_disable, chan);
+}
+EXPORT_SYMBOL_GPL(iio_backend_chan_disable);
+
+/**
+ * iio_backend_chan_enable - Enable the backend.
+ * @back:	Backend device
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_enable(struct iio_backend *back)
+{
+	return iio_backend_op_call(back, enable);
+}
+EXPORT_SYMBOL_GPL(iio_backend_enable);
+
+/**
+ * iio_backend_disable - Disable the backend.
+ * @back:	Backend device
+ */
+void iio_backend_disable(struct iio_backend *back)
+{
+	iio_backend_void_op_call(back, disable);
+}
+EXPORT_SYMBOL_GPL(iio_backend_disable);
+
+/**
+ * iio_backend_data_format_set - Configure the channel data format
+ * @back:	Backend device
+ * @chan:	Channel number.
+ * @data:	Data format.
+ *
+ * Properly configure a channel with respect to the expected data format. A
+ * @struct iio_backend_data_fmt must be passed with the settings.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure
+ */
+int iio_backend_data_format_set(struct iio_backend *back, unsigned int chan,
+				const struct iio_backend_data_fmt *data)
+{
+	if (!data || data->type >= IIO_BACKEND_DATA_TYPE_MAX)
+		return -EINVAL;
+
+	return iio_backend_op_call(back, data_format_set, chan, data);
+}
+EXPORT_SYMBOL_GPL(iio_backend_data_format_set);
+
+static void iio_backend_free_buffer(void *arg)
+{
+	struct iio_backend_buffer_pair *pair = arg;
+
+	iio_backend_void_op_call(pair->back, free_buffer, pair->buffer);
+}
+
+/**
+ * devm_iio_backend_request_buffer - Request an IIO buffer from the backend.
+ * @dev:	Device to bind the buffer lifetime.
+ * @back:	Backend device.
+ * @indio_dev:	IIO device.
+ *
+ * Request an IIO buffer from the backend. The type of the buffer (typically
+ * INDIO_BUFFER_HARDWARE) is up to the backend to decide. This is because,
+ * normally, the backend dictates what kind of buffering we can get.
+ *
+ * The backend .free_buffer() hooks is automatically called on @dev detach.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure
+ */
+int devm_iio_backend_request_buffer(struct device *dev,
+				    struct iio_backend *back,
+				    struct iio_dev *indio_dev)
+{
+	struct iio_backend_buffer_pair *pair;
+	struct iio_buffer *buffer;
+
+	buffer = iio_backend_ptr_op_call(back, request_buffer, indio_dev);
+	if (IS_ERR(buffer))
+		return PTR_ERR(buffer);
+
+	/* backend lock should not be need after getting the buffer */
+	pair = devm_kzalloc(dev, sizeof(*pair), GFP_KERNEL);
+	if (!pair)
+		return -ENOMEM;
+
+	/* weak reference should be all what we need */
+	pair->back = back;
+	pair->buffer = buffer;
+
+	return devm_add_action_or_reset(dev, iio_backend_free_buffer, pair);
+}
+EXPORT_SYMBOL_GPL(devm_iio_backend_request_buffer);
+
+static void iio_backend_free(struct kref *ref)
+{
+	struct iio_backend *back = container_of(ref, struct iio_backend, ref);
+
+	kfree(back);
+}
+
+static void iio_backend_release(void *arg)
+{
+	struct iio_backend *back = arg;
+
+	module_put(back->owner);
+	kref_put(&back->ref, iio_backend_free);
+}
+
+/**
+ * devm_iio_backend_get - Get a backend device
+ * @dev:	Device where to look for the backend.
+ * @name:	Backend name.
+ *
+ * Get's the backend associated with @dev.
+ *
+ * RETURNS:
+ * A backend pointer, negative error pointer otherwise.
+ */
+struct iio_backend *devm_iio_backend_get(struct device *dev, const char *name)
+{
+	struct fwnode_handle *fwnode;
+	struct iio_backend *back;
+	int index = 0, ret;
+
+	if (name) {
+		index = device_property_match_string(dev, "io-backends-names",
+						     name);
+		if (index < 0)
+			return ERR_PTR(index);
+	}
+
+	fwnode = fwnode_find_reference(dev_fwnode(dev), "io-backends", index);
+	if (IS_ERR(fwnode)) {
+		dev_err(dev, "Cannot get Firmware reference\n");
+		return ERR_CAST(fwnode);
+	}
+
+	guard(mutex)(&iio_back_lock);
+	list_for_each_entry(back, &iio_back_list, entry) {
+		struct device_link *link;
+
+		if (!device_match_fwnode(back->dev, fwnode))
+			continue;
+
+		fwnode_handle_put(fwnode);
+		kref_get(&back->ref);
+		if (!try_module_get(back->owner)) {
+			dev_err(dev, "Cannot get module reference\n");
+			return ERR_PTR(-ENODEV);
+		}
+
+		ret = devm_add_action_or_reset(dev, iio_backend_release, back);
+		if (ret)
+			return ERR_PTR(ret);
+
+		link = device_link_add(dev, back->dev,
+				       DL_FLAG_AUTOREMOVE_CONSUMER);
+		if (!link)
+			dev_warn(dev, "Could not link to supplier(%s)\n",
+				 dev_name(back->dev));
+
+		dev_dbg(dev, "Found backend(%s) device\n", dev_name(back->dev));
+		return back;
+	}
+
+	fwnode_handle_put(fwnode);
+	return ERR_PTR(-EPROBE_DEFER);
+}
+EXPORT_SYMBOL_GPL(devm_iio_backend_get);
+
+/**
+ * iio_backend_get_priv - Get driver private data
+ * @back:	Backend device
+ */
+void *iio_backend_get_priv(const struct iio_backend *back)
+{
+	return back->priv;
+}
+EXPORT_SYMBOL_GPL(iio_backend_get_priv);
+
+static void iio_backend_unregister(void *arg)
+{
+	struct iio_backend *back = arg;
+
+	mutex_lock(&iio_back_lock);
+	list_del(&back->entry);
+	mutex_unlock(&iio_back_lock);
+
+	mutex_lock(&back->lock);
+	back->ops = NULL;
+	mutex_unlock(&back->lock);
+	kref_put(&back->ref, iio_backend_free);
+}
+
+/**
+ * devm_iio_backend_register - Register a new backend device
+ * @dev:	Backend device being registered.
+ * @ops:	Backend ops
+ * @priv:	Device private data.
+ *
+ * @ops and @priv are both mandatory. Not providing them results in -EINVAL.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int devm_iio_backend_register(struct device *dev,
+			      const struct iio_backend_ops *ops, void *priv)
+{
+	struct iio_backend *back;
+
+	if (!ops || !priv) {
+		dev_err(dev, "No backend ops or private data given\n");
+		return -EINVAL;
+	}
+
+	back = kzalloc(sizeof(*back), GFP_KERNEL);
+	if (!back)
+		return -ENOMEM;
+
+	kref_init(&back->ref);
+	mutex_init(&back->lock);
+	back->ops = ops;
+	back->owner = dev->driver->owner;
+	back->dev = dev;
+	back->priv = priv;
+	mutex_lock(&iio_back_lock);
+	list_add(&back->entry, &iio_back_list);
+	mutex_unlock(&iio_back_lock);
+
+	return devm_add_action_or_reset(dev, iio_backend_unregister, back);
+}
+EXPORT_SYMBOL_GPL(devm_iio_backend_register);
+
+MODULE_AUTHOR("Nuno Sa <nuno.sa@analog.com>");
+MODULE_DESCRIPTION("Framework to handle complex IIO aggregate devices");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/iio/backend.h b/include/linux/iio/backend.h
new file mode 100644
index 000000000000..d2555333cb19
--- /dev/null
+++ b/include/linux/iio/backend.h
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _IIO_BACKEND_H_
+#define _IIO_BACKEND_H_
+
+#include <linux/types.h>
+
+struct iio_backend;
+struct device;
+struct iio_dev;
+
+enum iio_backend_data_type {
+	IIO_BACKEND_TWOS_COMPLEMENT,
+	IIO_BACKEND_OFFSET_BINARY,
+	IIO_BACKEND_DATA_TYPE_MAX
+};
+
+/**
+ * struct iio_backend_data_fmt - Backend data format
+ * @type:		Data type.
+ * @sign_extend:	Bool to tell if the data is sign extended.
+ * @enable:		Enable/Disable the data format module. If disabled,
+ *			not formatting will happen.
+ */
+struct iio_backend_data_fmt {
+	enum iio_backend_data_type type;
+	bool sign_extend;
+	bool enable;
+};
+
+/**
+ * struct iio_backend_ops - operations structure for an iio_backend
+ * @enable:		Enable backend.
+ * @disable:		Disable backend.
+ * @chan_enable:	Enable one channel.
+ * @chan_disable:	Disable one channel.
+ * @data_format_set:	Configure the data format for a specific channel.
+ * @request_buffer:	Request an IIO buffer.
+ * @free_buffer:	Free an IIO buffer.
+ **/
+struct iio_backend_ops {
+	int (*enable)(struct iio_backend *back);
+	void (*disable)(struct iio_backend *back);
+	int (*chan_enable)(struct iio_backend *back, unsigned int chan);
+	int (*chan_disable)(struct iio_backend *back, unsigned int chan);
+	int (*data_format_set)(struct iio_backend *back, unsigned int chan,
+			       const struct iio_backend_data_fmt *data);
+	struct iio_buffer *(*request_buffer)(struct iio_backend *back,
+					     struct iio_dev *indio_dev);
+	void (*free_buffer)(struct iio_backend *back,
+			    struct iio_buffer *buffer);
+};
+
+int iio_backend_chan_enable(struct iio_backend *back, unsigned int chan);
+int iio_backend_chan_disable(struct iio_backend *back, unsigned int chan);
+int iio_backend_enable(struct iio_backend *back);
+void iio_backend_disable(struct iio_backend *back);
+int iio_backend_data_format_set(struct iio_backend *back, unsigned int chan,
+				const struct iio_backend_data_fmt *data);
+int devm_iio_backend_request_buffer(struct device *dev,
+				    struct iio_backend *back,
+				    struct iio_dev *indio_dev);
+
+void *iio_backend_get_priv(const struct iio_backend *conv);
+struct iio_backend *devm_iio_backend_get(struct device *dev, const char *name);
+int devm_iio_backend_register(struct device *dev,
+			      const struct iio_backend_ops *ops, void *priv);
+
+#endif

-- 
2.43.0

Re: [PATCH v2 6/8] iio: add the IIO backend framework

[Jonathan Cameron]

On Fri, 08 Dec 2023 16:14:13 +0100
Nuno Sa via B4 Relay <devnull+nuno.sa.analog.com@kernel.org> wrote:

> From: Nuno Sa <nuno.sa@analog.com>
> 
> This is a Framework to handle complex IIO aggregate devices.
> 
> The typical architecture is to have one device as the frontend device which
> can be "linked" against one or multiple backend devices. All the IIO and
> userspace interface is expected to be registers/managed by the frontend
> device which will callback into the backends when needed (to get/set
> some configuration that it does not directly control).
> 
> The basic framework interface is pretty simple:
>  - Backends should register themselves with @devm_iio_backend_register()
>  - Frontend devices should get backends with @devm_iio_backend_get()
> 
> Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Name space all the Symbol Exports. Otherwise, no particular comments from me.
I will take a deeper look at all the details at somepoint, but so far
it looks basically fine to me.

Jonathan

[PATCH v2 7/8] iio: adc: ad9467: convert to backend framework

[Nuno Sa via B4 Relay]

From: Nuno Sa <nuno.sa@analog.com>

Convert the driver to use the new IIO backend framework. The device
functionality is expected to be the same (meaning no added or removed
features).

Also note this patch effectively breaks ABI and that's needed so we can
properly support this device and add needed features making use of the
new IIO framework.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
 drivers/iio/adc/Kconfig  |   2 +-
 drivers/iio/adc/ad9467.c | 242 +++++++++++++++++++++++++++--------------------
 2 files changed, 143 insertions(+), 101 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 1e2b7a2c67c6..af56df63beff 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -275,7 +275,7 @@ config AD799X
 config AD9467
 	tristate "Analog Devices AD9467 High Speed ADC driver"
 	depends on SPI
-	depends on ADI_AXI_ADC
+	select IIO_BACKEND
 	help
 	  Say yes here to build support for Analog Devices:
 	  * AD9467 16-Bit, 200 MSPS/250 MSPS Analog-to-Digital Converter
diff --git a/drivers/iio/adc/ad9467.c b/drivers/iio/adc/ad9467.c
index 6581fce4ba95..c4d797aee9c7 100644
--- a/drivers/iio/adc/ad9467.c
+++ b/drivers/iio/adc/ad9467.c
@@ -16,13 +16,13 @@
 #include <linux/gpio/consumer.h>
 #include <linux/of.h>
 
-
+#include <linux/iio/buffer-dmaengine.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 
 #include <linux/clk.h>
 
-#include <linux/iio/adc/adi-axi-adc.h>
+#include <linux/iio/backend.h>
 
 /*
  * ADI High-Speed ADC common spi interface registers
@@ -102,15 +102,20 @@
 #define AD9467_REG_VREF_MASK		0x0F
 
 struct ad9467_chip_info {
-	struct adi_axi_adc_chip_info	axi_adc_info;
-	unsigned int			default_output_mode;
-	unsigned int			vref_mask;
+	const char		*name;
+	unsigned int		id;
+	const struct		iio_chan_spec *channels;
+	unsigned int		num_channels;
+	const unsigned int	(*scale_table)[2];
+	int			num_scales;
+	unsigned long		max_rate;
+	unsigned int		default_output_mode;
+	unsigned int		vref_mask;
 };
 
-#define to_ad9467_chip_info(_info)	\
-	container_of(_info, struct ad9467_chip_info, axi_adc_info)
-
 struct ad9467_state {
+	const struct ad9467_chip_info	*info;
+	struct iio_backend		*back;
 	struct spi_device		*spi;
 	struct clk			*clk;
 	unsigned int			output_mode;
@@ -151,10 +156,10 @@ static int ad9467_spi_write(struct spi_device *spi, unsigned int reg,
 	return spi_write(spi, buf, ARRAY_SIZE(buf));
 }
 
-static int ad9467_reg_access(struct adi_axi_adc_conv *conv, unsigned int reg,
+static int ad9467_reg_access(struct iio_dev *indio_dev, unsigned int reg,
 			     unsigned int writeval, unsigned int *readval)
 {
-	struct ad9467_state *st = adi_axi_adc_conv_priv(conv);
+	struct ad9467_state *st = iio_priv(indio_dev);
 	struct spi_device *spi = st->spi;
 	int ret;
 
@@ -191,14 +196,13 @@ static const unsigned int ad9467_scale_table[][2] = {
 	{2300, 8}, {2400, 9}, {2500, 10},
 };
 
-static void __ad9467_get_scale(struct adi_axi_adc_conv *conv, int index,
+static void __ad9467_get_scale(struct ad9467_state *st, int index,
 			       unsigned int *val, unsigned int *val2)
 {
-	const struct adi_axi_adc_chip_info *info = conv->chip_info;
-	const struct iio_chan_spec *chan = &info->channels[0];
+	const struct iio_chan_spec *chan = &st->info->channels[0];
 	unsigned int tmp;
 
-	tmp = (info->scale_table[index][0] * 1000000ULL) >>
+	tmp = (st->info->scale_table[index][0] * 1000000ULL) >>
 			chan->scan_type.realbits;
 	*val = tmp / 1000000;
 	*val2 = tmp % 1000000;
@@ -229,52 +233,43 @@ static const struct iio_chan_spec ad9467_channels[] = {
 };
 
 static const struct ad9467_chip_info ad9467_chip_tbl = {
-	.axi_adc_info = {
-		.name = "ad9467",
-		.id = CHIPID_AD9467,
-		.max_rate = 250000000UL,
-		.scale_table = ad9467_scale_table,
-		.num_scales = ARRAY_SIZE(ad9467_scale_table),
-		.channels = ad9467_channels,
-		.num_channels = ARRAY_SIZE(ad9467_channels),
-	},
+	.name = "ad9467",
+	.id = CHIPID_AD9467,
+	.max_rate = 250000000UL,
+	.scale_table = ad9467_scale_table,
+	.num_scales = ARRAY_SIZE(ad9467_scale_table),
+	.channels = ad9467_channels,
+	.num_channels = ARRAY_SIZE(ad9467_channels),
 	.default_output_mode = AD9467_DEF_OUTPUT_MODE,
 	.vref_mask = AD9467_REG_VREF_MASK,
 };
 
 static const struct ad9467_chip_info ad9434_chip_tbl = {
-	.axi_adc_info = {
-		.name = "ad9434",
-		.id = CHIPID_AD9434,
-		.max_rate = 500000000UL,
-		.scale_table = ad9434_scale_table,
-		.num_scales = ARRAY_SIZE(ad9434_scale_table),
-		.channels = ad9434_channels,
-		.num_channels = ARRAY_SIZE(ad9434_channels),
-	},
+	.name = "ad9434",
+	.id = CHIPID_AD9434,
+	.max_rate = 500000000UL,
+	.scale_table = ad9434_scale_table,
+	.num_scales = ARRAY_SIZE(ad9434_scale_table),
+	.channels = ad9434_channels,
+	.num_channels = ARRAY_SIZE(ad9434_channels),
 	.default_output_mode = AD9434_DEF_OUTPUT_MODE,
 	.vref_mask = AD9434_REG_VREF_MASK,
 };
 
 static const struct ad9467_chip_info ad9265_chip_tbl = {
-	.axi_adc_info = {
-		.name = "ad9265",
-		.id = CHIPID_AD9265,
-		.max_rate = 125000000UL,
-		.scale_table = ad9265_scale_table,
-		.num_scales = ARRAY_SIZE(ad9265_scale_table),
-		.channels = ad9467_channels,
-		.num_channels = ARRAY_SIZE(ad9467_channels),
-	},
+	.name = "ad9265",
+	.id = CHIPID_AD9265,
+	.max_rate = 125000000UL,
+	.scale_table = ad9265_scale_table,
+	.num_scales = ARRAY_SIZE(ad9265_scale_table),
+	.channels = ad9467_channels,
+	.num_channels = ARRAY_SIZE(ad9467_channels),
 	.default_output_mode = AD9265_DEF_OUTPUT_MODE,
 	.vref_mask = AD9265_REG_VREF_MASK,
 };
 
-static int ad9467_get_scale(struct adi_axi_adc_conv *conv, int *val, int *val2)
+static int ad9467_get_scale(struct ad9467_state *st, int *val, int *val2)
 {
-	const struct adi_axi_adc_chip_info *info = conv->chip_info;
-	const struct ad9467_chip_info *info1 = to_ad9467_chip_info(info);
-	struct ad9467_state *st = adi_axi_adc_conv_priv(conv);
 	unsigned int i, vref_val;
 	int ret;
 
@@ -282,25 +277,23 @@ static int ad9467_get_scale(struct adi_axi_adc_conv *conv, int *val, int *val2)
 	if (ret < 0)
 		return ret;
 
-	vref_val = ret & info1->vref_mask;
+	vref_val = ret & st->info->vref_mask;
 
-	for (i = 0; i < info->num_scales; i++) {
-		if (vref_val == info->scale_table[i][1])
+	for (i = 0; i < st->info->num_scales; i++) {
+		if (vref_val == st->info->scale_table[i][1])
 			break;
 	}
 
-	if (i == info->num_scales)
+	if (i == st->info->num_scales)
 		return -ERANGE;
 
-	__ad9467_get_scale(conv, i, val, val2);
+	__ad9467_get_scale(st, i, val, val2);
 
 	return IIO_VAL_INT_PLUS_MICRO;
 }
 
-static int ad9467_set_scale(struct adi_axi_adc_conv *conv, int val, int val2)
+static int ad9467_set_scale(struct ad9467_state *st, int val, int val2)
 {
-	const struct adi_axi_adc_chip_info *info = conv->chip_info;
-	struct ad9467_state *st = adi_axi_adc_conv_priv(conv);
 	unsigned int scale_val[2];
 	unsigned int i;
 	int ret;
@@ -308,14 +301,14 @@ static int ad9467_set_scale(struct adi_axi_adc_conv *conv, int val, int val2)
 	if (val != 0)
 		return -EINVAL;
 
-	for (i = 0; i < info->num_scales; i++) {
-		__ad9467_get_scale(conv, i, &scale_val[0], &scale_val[1]);
+	for (i = 0; i < st->info->num_scales; i++) {
+		__ad9467_get_scale(st, i, &scale_val[0], &scale_val[1]);
 		if (scale_val[0] != val || scale_val[1] != val2)
 			continue;
 
 		guard(mutex)(&st->lock);
 		ret = ad9467_spi_write(st->spi, AN877_ADC_REG_VREF,
-				       info->scale_table[i][1]);
+				       st->info->scale_table[i][1]);
 		if (ret < 0)
 			return ret;
 
@@ -326,15 +319,15 @@ static int ad9467_set_scale(struct adi_axi_adc_conv *conv, int val, int val2)
 	return -EINVAL;
 }
 
-static int ad9467_read_raw(struct adi_axi_adc_conv *conv,
+static int ad9467_read_raw(struct iio_dev *indio_dev,
 			   struct iio_chan_spec const *chan,
 			   int *val, int *val2, long m)
 {
-	struct ad9467_state *st = adi_axi_adc_conv_priv(conv);
+	struct ad9467_state *st = iio_priv(indio_dev);
 
 	switch (m) {
 	case IIO_CHAN_INFO_SCALE:
-		return ad9467_get_scale(conv, val, val2);
+		return ad9467_get_scale(st, val, val2);
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		*val = clk_get_rate(st->clk);
 
@@ -344,20 +337,19 @@ static int ad9467_read_raw(struct adi_axi_adc_conv *conv,
 	}
 }
 
-static int ad9467_write_raw(struct adi_axi_adc_conv *conv,
+static int ad9467_write_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *chan,
 			    int val, int val2, long mask)
 {
-	const struct adi_axi_adc_chip_info *info = conv->chip_info;
-	struct ad9467_state *st = adi_axi_adc_conv_priv(conv);
+	struct ad9467_state *st = iio_priv(indio_dev);
 	long r_clk;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_SCALE:
-		return ad9467_set_scale(conv, val, val2);
+		return ad9467_set_scale(st, val, val2);
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		r_clk = clk_round_rate(st->clk, val);
-		if (r_clk < 0 || r_clk > info->max_rate) {
+		if (r_clk < 0 || r_clk > st->info->max_rate) {
 			dev_warn(&st->spi->dev,
 				 "Error setting ADC sample rate %ld", r_clk);
 			return -EINVAL;
@@ -369,26 +361,53 @@ static int ad9467_write_raw(struct adi_axi_adc_conv *conv,
 	}
 }
 
-static int ad9467_read_avail(struct adi_axi_adc_conv *conv,
+static int ad9467_read_avail(struct iio_dev *indio_dev,
 			     struct iio_chan_spec const *chan,
 			     const int **vals, int *type, int *length,
 			     long mask)
 {
-	const struct adi_axi_adc_chip_info *info = conv->chip_info;
-	struct ad9467_state *st = adi_axi_adc_conv_priv(conv);
+	struct ad9467_state *st = iio_priv(indio_dev);
 
 	switch (mask) {
 	case IIO_CHAN_INFO_SCALE:
 		*vals = (const int *)st->scales;
 		*type = IIO_VAL_INT_PLUS_MICRO;
 		/* Values are stored in a 2D matrix */
-		*length = info->num_scales * 2;
+		*length = st->info->num_scales * 2;
 		return IIO_AVAIL_LIST;
 	default:
 		return -EINVAL;
 	}
 }
 
+static int ad9467_update_scan_mode(struct iio_dev *indio_dev,
+				   const unsigned long *scan_mask)
+{
+	struct ad9467_state *st = iio_priv(indio_dev);
+	unsigned int c;
+	int ret;
+
+	for (c = 0; c < st->info->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 ad9467_info = {
+	.read_raw = ad9467_read_raw,
+	.write_raw = ad9467_write_raw,
+	.update_scan_mode = ad9467_update_scan_mode,
+	.debugfs_reg_access = ad9467_reg_access,
+	.read_avail = ad9467_read_avail,
+};
+
 static int ad9467_outputmode_set(struct spi_device *spi, unsigned int mode)
 {
 	int ret;
@@ -401,19 +420,17 @@ static int ad9467_outputmode_set(struct spi_device *spi, unsigned int mode)
 				AN877_ADC_TRANSFER_SYNC);
 }
 
-static int ad9467_scale_fill(struct adi_axi_adc_conv *conv)
+static int ad9467_scale_fill(struct ad9467_state *st)
 {
-	const struct adi_axi_adc_chip_info *info = conv->chip_info;
-	struct ad9467_state *st = adi_axi_adc_conv_priv(conv);
 	unsigned int i, val1, val2;
 
-	st->scales = devm_kmalloc_array(&st->spi->dev, info->num_scales,
+	st->scales = devm_kmalloc_array(&st->spi->dev, st->info->num_scales,
 					sizeof(*st->scales), GFP_KERNEL);
 	if (!st->scales)
 		return -ENOMEM;
 
-	for (i = 0; i < info->num_scales; i++) {
-		__ad9467_get_scale(conv, i, &val1, &val2);
+	for (i = 0; i < st->info->num_scales; i++) {
+		__ad9467_get_scale(st, i, &val1, &val2);
 		st->scales[i][0] = val1;
 		st->scales[i][1] = val2;
 	}
@@ -421,11 +438,27 @@ static int ad9467_scale_fill(struct adi_axi_adc_conv *conv)
 	return 0;
 }
 
-static int ad9467_preenable_setup(struct adi_axi_adc_conv *conv)
+static int ad9467_setup(struct ad9467_state *st)
 {
-	struct ad9467_state *st = adi_axi_adc_conv_priv(conv);
+	struct iio_backend_data_fmt data = {
+		.sign_extend = true,
+		.enable = true,
+	};
+	unsigned int c, mode;
+	int ret;
+
+	mode = st->info->default_output_mode | AN877_ADC_OUTPUT_MODE_TWOS_COMPLEMENT;
+	ret = ad9467_outputmode_set(st->spi, mode);
+	if (ret)
+		return ret;
+
+	for (c = 0; c < st->info->num_channels; c++) {
+		ret = iio_backend_data_format_set(st->back, c, &data);
+		if (ret)
+			return ret;
+	}
 
-	return ad9467_outputmode_set(st->spi, st->output_mode);
+	return 0;
 }
 
 static int ad9467_reset(struct device *dev)
@@ -445,23 +478,22 @@ static int ad9467_reset(struct device *dev)
 
 static int ad9467_probe(struct spi_device *spi)
 {
-	const struct ad9467_chip_info *info;
-	struct adi_axi_adc_conv *conv;
+	struct iio_dev *indio_dev;
 	struct ad9467_state *st;
 	unsigned int id;
 	int ret;
 
-	info = spi_get_device_match_data(spi);
-	if (!info)
-		return -ENODEV;
-
-	conv = devm_adi_axi_adc_conv_register(&spi->dev, sizeof(*st));
-	if (IS_ERR(conv))
-		return PTR_ERR(conv);
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
 
-	st = adi_axi_adc_conv_priv(conv);
+	st = iio_priv(indio_dev);
 	st->spi = spi;
 
+	st->info = spi_get_device_match_data(spi);
+	if (!st->info)
+		return -ENODEV;
+
 	st->clk = devm_clk_get_enabled(&spi->dev, "adc-clk");
 	if (IS_ERR(st->clk))
 		return PTR_ERR(st->clk);
@@ -475,29 +507,39 @@ static int ad9467_probe(struct spi_device *spi)
 	if (ret)
 		return ret;
 
-	conv->chip_info = &info->axi_adc_info;
-
-	ret = ad9467_scale_fill(conv);
+	ret = ad9467_scale_fill(st);
 	if (ret)
 		return ret;
 
 	id = ad9467_spi_read(spi, AN877_ADC_REG_CHIP_ID);
-	if (id != conv->chip_info->id) {
+	if (id != st->info->id) {
 		dev_err(&spi->dev, "Mismatch CHIP_ID, got 0x%X, expected 0x%X\n",
-			id, conv->chip_info->id);
+			id, st->info->id);
 		return -ENODEV;
 	}
 
-	conv->reg_access = ad9467_reg_access;
-	conv->write_raw = ad9467_write_raw;
-	conv->read_raw = ad9467_read_raw;
-	conv->read_avail = ad9467_read_avail;
-	conv->preenable_setup = ad9467_preenable_setup;
+	indio_dev->name = st->info->name;
+	indio_dev->channels = st->info->channels;
+	indio_dev->num_channels = st->info->num_channels;
+	indio_dev->info = &ad9467_info;
 
-	st->output_mode = info->default_output_mode |
-			  AN877_ADC_OUTPUT_MODE_TWOS_COMPLEMENT;
+	st->back = devm_iio_backend_get(&spi->dev, NULL);
+	if (IS_ERR(st->back))
+		return PTR_ERR(st->back);
 
-	return 0;
+	ret = devm_iio_backend_request_buffer(&spi->dev, st->back, indio_dev);
+	if (ret)
+		return ret;
+
+	ret = iio_backend_enable(st->back);
+	if (ret)
+		return ret;
+
+	ret = ad9467_setup(st);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(&spi->dev, indio_dev);
 }
 
 static const struct of_device_id ad9467_of_match[] = {

-- 
2.43.0

[PATCH v2 8/8] iio: adc: adi-axi-adc: move to backend framework

[Nuno Sa via B4 Relay]

From: Nuno Sa <nuno.sa@analog.com>

Move to the IIO backend framework. Devices supported by adi-axi-adc now
register themselves as backend devices.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
 drivers/iio/adc/Kconfig             |   1 +
 drivers/iio/adc/adi-axi-adc.c       | 379 +++++++++---------------------------
 include/linux/iio/adc/adi-axi-adc.h |  68 -------
 3 files changed, 92 insertions(+), 356 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index af56df63beff..cc42a3399c63 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -292,6 +292,7 @@ config ADI_AXI_ADC
 	select IIO_BUFFER
 	select IIO_BUFFER_HW_CONSUMER
 	select IIO_BUFFER_DMAENGINE
+	select IIO_BACKEND
 	depends on HAS_IOMEM
 	depends on OF
 	help
diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
index c247ff1541d2..f409cfe0910a 100644
--- a/drivers/iio/adc/adi-axi-adc.c
+++ b/drivers/iio/adc/adi-axi-adc.c
@@ -6,6 +6,7 @@
  * Copyright 2012-2020 Analog Devices Inc.
  */
 
+#include "linux/err.h"
 #include <linux/bitfield.h>
 #include <linux/clk.h>
 #include <linux/io.h>
@@ -17,13 +18,11 @@
 #include <linux/regmap.h>
 #include <linux/slab.h>
 
-#include <linux/iio/iio.h>
-#include <linux/iio/sysfs.h>
-#include <linux/iio/buffer.h>
-#include <linux/iio/buffer-dmaengine.h>
-
 #include <linux/fpga/adi-axi-common.h>
-#include <linux/iio/adc/adi-axi-adc.h>
+#include <linux/iio/backend.h>
+#include <linux/iio/buffer-dmaengine.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
 
 /*
  * Register definitions:
@@ -44,6 +43,7 @@
 #define   ADI_AXI_REG_CHAN_CTRL_PN_SEL_OWR	BIT(10)
 #define   ADI_AXI_REG_CHAN_CTRL_IQCOR_EN	BIT(9)
 #define   ADI_AXI_REG_CHAN_CTRL_DCFILT_EN	BIT(8)
+#define   ADI_AXI_REG_CHAN_CTRL_FMT_MASK	GENMASK(6, 4)
 #define   ADI_AXI_REG_CHAN_CTRL_FMT_SIGNEXT	BIT(6)
 #define   ADI_AXI_REG_CHAN_CTRL_FMT_TYPE	BIT(5)
 #define   ADI_AXI_REG_CHAN_CTRL_FMT_EN		BIT(4)
@@ -55,286 +55,100 @@
 	 ADI_AXI_REG_CHAN_CTRL_FMT_EN |		\
 	 ADI_AXI_REG_CHAN_CTRL_ENABLE)
 
-struct adi_axi_adc_core_info {
-	unsigned int				version;
-};
-
 struct adi_axi_adc_state {
-	struct mutex				lock;
-
-	struct adi_axi_adc_client		*client;
 	struct regmap				*regmap;
-};
-
-struct adi_axi_adc_client {
-	struct list_head			entry;
-	struct adi_axi_adc_conv			conv;
-	struct adi_axi_adc_state		*state;
 	struct device				*dev;
-	const struct adi_axi_adc_core_info	*info;
 };
 
-static LIST_HEAD(registered_clients);
-static DEFINE_MUTEX(registered_clients_lock);
-
-static struct adi_axi_adc_client *conv_to_client(struct adi_axi_adc_conv *conv)
-{
-	return container_of(conv, struct adi_axi_adc_client, conv);
-}
-
-void *adi_axi_adc_conv_priv(struct adi_axi_adc_conv *conv)
-{
-	struct adi_axi_adc_client *cl = conv_to_client(conv);
-
-	return (char *)cl + ALIGN(sizeof(struct adi_axi_adc_client),
-				  IIO_DMA_MINALIGN);
-}
-EXPORT_SYMBOL_NS_GPL(adi_axi_adc_conv_priv, IIO_ADI_AXI);
-
-static int adi_axi_adc_config_dma_buffer(struct device *dev,
-					 struct iio_dev *indio_dev)
-{
-	const char *dma_name;
-
-	if (!device_property_present(dev, "dmas"))
-		return 0;
-
-	if (device_property_read_string(dev, "dma-names", &dma_name))
-		dma_name = "rx";
-
-	return devm_iio_dmaengine_buffer_setup(indio_dev->dev.parent,
-					       indio_dev, dma_name);
-}
-
-static int adi_axi_adc_read_raw(struct iio_dev *indio_dev,
-				struct iio_chan_spec const *chan,
-				int *val, int *val2, long mask)
-{
-	struct adi_axi_adc_state *st = iio_priv(indio_dev);
-	struct adi_axi_adc_conv *conv = &st->client->conv;
-
-	if (!conv->read_raw)
-		return -EOPNOTSUPP;
-
-	return conv->read_raw(conv, chan, val, val2, mask);
-}
-
-static int adi_axi_adc_write_raw(struct iio_dev *indio_dev,
-				 struct iio_chan_spec const *chan,
-				 int val, int val2, long mask)
-{
-	struct adi_axi_adc_state *st = iio_priv(indio_dev);
-	struct adi_axi_adc_conv *conv = &st->client->conv;
-
-	if (!conv->write_raw)
-		return -EOPNOTSUPP;
-
-	return conv->write_raw(conv, chan, val, val2, mask);
-}
-
-static int adi_axi_adc_read_avail(struct iio_dev *indio_dev,
-				  struct iio_chan_spec const *chan,
-				  const int **vals, int *type, int *length,
-				  long mask)
+static int axi_adc_enable(struct iio_backend *back)
 {
-	struct adi_axi_adc_state *st = iio_priv(indio_dev);
-	struct adi_axi_adc_conv *conv = &st->client->conv;
-
-	if (!conv->read_avail)
-		return -EOPNOTSUPP;
-
-	return conv->read_avail(conv, chan, vals, type, length, mask);
-}
-
-static int adi_axi_adc_update_scan_mode(struct iio_dev *indio_dev,
-					const unsigned long *scan_mask)
-{
-	struct adi_axi_adc_state *st = iio_priv(indio_dev);
-	struct adi_axi_adc_conv *conv = &st->client->conv;
-	unsigned int i;
+	struct adi_axi_adc_state *st = iio_backend_get_priv(back);
 	int ret;
 
-	for (i = 0; i < conv->chip_info->num_channels; i++) {
-		if (test_bit(i, scan_mask))
-			ret = regmap_set_bits(st->regmap,
-					      ADI_AXI_REG_CHAN_CTRL(i),
-					      ADI_AXI_REG_CHAN_CTRL_ENABLE);
-		else
-			ret = regmap_clear_bits(st->regmap,
-						ADI_AXI_REG_CHAN_CTRL(i),
-						ADI_AXI_REG_CHAN_CTRL_ENABLE);
-		if (ret)
-			return ret;
-	}
+	ret = regmap_set_bits(st->regmap, ADI_AXI_REG_RSTN,
+			      ADI_AXI_REG_RSTN_MMCM_RSTN);
+	if (ret)
+		return ret;
 
-	return 0;
+	fsleep(10);
+	return regmap_set_bits(st->regmap, ADI_AXI_REG_RSTN,
+			       ADI_AXI_REG_RSTN_RSTN | ADI_AXI_REG_RSTN_MMCM_RSTN);
 }
 
-static struct adi_axi_adc_conv *adi_axi_adc_conv_register(struct device *dev,
-							  size_t sizeof_priv)
+static void axi_adc_disable(struct iio_backend *back)
 {
-	struct adi_axi_adc_client *cl;
-	size_t alloc_size;
-
-	alloc_size = ALIGN(sizeof(struct adi_axi_adc_client), IIO_DMA_MINALIGN);
-	if (sizeof_priv)
-		alloc_size += ALIGN(sizeof_priv, IIO_DMA_MINALIGN);
+	struct adi_axi_adc_state *st = iio_backend_get_priv(back);
 
-	cl = kzalloc(alloc_size, GFP_KERNEL);
-	if (!cl)
-		return ERR_PTR(-ENOMEM);
-
-	mutex_lock(&registered_clients_lock);
-
-	cl->dev = get_device(dev);
-
-	list_add_tail(&cl->entry, &registered_clients);
-
-	mutex_unlock(&registered_clients_lock);
-
-	return &cl->conv;
+	regmap_write(st->regmap, ADI_AXI_REG_RSTN, 0);
 }
 
-static void adi_axi_adc_conv_unregister(struct adi_axi_adc_conv *conv)
+static int axi_adc_data_format_set(struct iio_backend *back, unsigned int chan,
+				   const struct iio_backend_data_fmt *data)
 {
-	struct adi_axi_adc_client *cl = conv_to_client(conv);
-
-	mutex_lock(&registered_clients_lock);
+	struct adi_axi_adc_state *st = iio_backend_get_priv(back);
+	u32 val;
 
-	list_del(&cl->entry);
-	put_device(cl->dev);
+	if (!data->enable)
+		return regmap_clear_bits(st->regmap,
+					 ADI_AXI_REG_CHAN_CTRL(chan),
+					 ADI_AXI_REG_CHAN_CTRL_FMT_EN);
 
-	mutex_unlock(&registered_clients_lock);
+	val = FIELD_PREP(ADI_AXI_REG_CHAN_CTRL_FMT_EN, true);
+	if (data->sign_extend)
+		val |= FIELD_PREP(ADI_AXI_REG_CHAN_CTRL_FMT_SIGNEXT, true);
+	if (data->type == IIO_BACKEND_OFFSET_BINARY)
+		val |= FIELD_PREP(ADI_AXI_REG_CHAN_CTRL_FMT_TYPE, true);
 
-	kfree(cl);
+	return regmap_update_bits(st->regmap, ADI_AXI_REG_CHAN_CTRL(chan),
+				  ADI_AXI_REG_CHAN_CTRL_FMT_MASK, val);
 }
 
-static void devm_adi_axi_adc_conv_release(void *conv)
+static int axi_adc_chan_enable(struct iio_backend *back, unsigned int chan)
 {
-	adi_axi_adc_conv_unregister(conv);
-}
-
-struct adi_axi_adc_conv *devm_adi_axi_adc_conv_register(struct device *dev,
-							size_t sizeof_priv)
-{
-	struct adi_axi_adc_conv *conv;
-	int ret;
-
-	conv = adi_axi_adc_conv_register(dev, sizeof_priv);
-	if (IS_ERR(conv))
-		return conv;
-
-	ret = devm_add_action_or_reset(dev, devm_adi_axi_adc_conv_release,
-				       conv);
-	if (ret)
-		return ERR_PTR(ret);
+	struct adi_axi_adc_state *st = iio_backend_get_priv(back);
 
-	return conv;
+	return regmap_set_bits(st->regmap, ADI_AXI_REG_CHAN_CTRL(chan),
+			       ADI_AXI_REG_CHAN_CTRL_ENABLE);
 }
-EXPORT_SYMBOL_NS_GPL(devm_adi_axi_adc_conv_register, IIO_ADI_AXI);
-
-static const struct iio_info adi_axi_adc_info = {
-	.read_raw = &adi_axi_adc_read_raw,
-	.write_raw = &adi_axi_adc_write_raw,
-	.update_scan_mode = &adi_axi_adc_update_scan_mode,
-	.read_avail = &adi_axi_adc_read_avail,
-};
 
-static const struct adi_axi_adc_core_info adi_axi_adc_10_0_a_info = {
-	.version = ADI_AXI_PCORE_VER(10, 0, 'a'),
-};
-
-static struct adi_axi_adc_client *adi_axi_adc_attach_client(struct device *dev)
+static int axi_adc_chan_disable(struct iio_backend *back, unsigned int chan)
 {
-	const struct adi_axi_adc_core_info *info;
-	struct adi_axi_adc_client *cl;
-	struct device_node *cln;
-
-	info = of_device_get_match_data(dev);
-	if (!info)
-		return ERR_PTR(-ENODEV);
-
-	cln = of_parse_phandle(dev->of_node, "adi,adc-dev", 0);
-	if (!cln) {
-		dev_err(dev, "No 'adi,adc-dev' node defined\n");
-		return ERR_PTR(-ENODEV);
-	}
-
-	mutex_lock(&registered_clients_lock);
+	struct adi_axi_adc_state *st = iio_backend_get_priv(back);
 
-	list_for_each_entry(cl, &registered_clients, entry) {
-		if (!cl->dev)
-			continue;
-
-		if (cl->dev->of_node != cln)
-			continue;
-
-		if (!try_module_get(cl->dev->driver->owner)) {
-			mutex_unlock(&registered_clients_lock);
-			of_node_put(cln);
-			return ERR_PTR(-ENODEV);
-		}
-
-		get_device(cl->dev);
-		cl->info = info;
-		mutex_unlock(&registered_clients_lock);
-		of_node_put(cln);
-		return cl;
-	}
-
-	mutex_unlock(&registered_clients_lock);
-	of_node_put(cln);
-
-	return ERR_PTR(-EPROBE_DEFER);
+	return regmap_clear_bits(st->regmap, ADI_AXI_REG_CHAN_CTRL(chan),
+				 ADI_AXI_REG_CHAN_CTRL_ENABLE);
 }
 
-static int adi_axi_adc_setup_channels(struct device *dev,
-				      struct adi_axi_adc_state *st)
+static struct iio_buffer *axi_adc_request_buffer(struct iio_backend *back,
+						 struct iio_dev *indio_dev)
 {
-	struct adi_axi_adc_conv *conv = &st->client->conv;
-	int i, ret;
+	struct adi_axi_adc_state *st = iio_backend_get_priv(back);
+	struct iio_buffer *buffer;
+	const char *dma_name;
+	int ret;
 
-	if (conv->preenable_setup) {
-		ret = conv->preenable_setup(conv);
-		if (ret)
-			return ret;
-	}
+	if (device_property_read_string(st->dev, "dma-names", &dma_name))
+		dma_name = "rx";
 
-	for (i = 0; i < conv->chip_info->num_channels; i++) {
-		ret = regmap_write(st->regmap, ADI_AXI_REG_CHAN_CTRL(i),
-				   ADI_AXI_REG_CHAN_CTRL_DEFAULTS);
-		if (ret)
-			return ret;
+	buffer = iio_dmaengine_buffer_alloc(st->dev, dma_name);
+	if (IS_ERR(buffer)) {
+		dev_err(st->dev, "Could not get DMA buffer, %ld\n",
+			PTR_ERR(buffer));
+		return ERR_CAST(buffer);
 	}
 
-	return 0;
-}
-
-static int axi_adc_reset(struct adi_axi_adc_state *st)
-{
-	int ret;
-
-	ret = regmap_write(st->regmap, ADI_AXI_REG_RSTN, 0);
-	if (ret)
-		return ret;
-
-	mdelay(10);
-	ret = regmap_write(st->regmap, ADI_AXI_REG_RSTN,
-			   ADI_AXI_REG_RSTN_MMCM_RSTN);
+	indio_dev->modes |= INDIO_BUFFER_HARDWARE;
+	ret = iio_device_attach_buffer(indio_dev, buffer);
 	if (ret)
-		return ret;
+		return ERR_PTR(ret);
 
-	mdelay(10);
-	return regmap_write(st->regmap, ADI_AXI_REG_RSTN,
-			    ADI_AXI_REG_RSTN_RSTN | ADI_AXI_REG_RSTN_MMCM_RSTN);
+	return buffer;
 }
 
-static void adi_axi_adc_cleanup(void *data)
+static void axi_adc_free_buffer(struct iio_backend *back,
+				struct iio_buffer *buffer)
 {
-	struct adi_axi_adc_client *cl = data;
-
-	put_device(cl->dev);
-	module_put(cl->dev->driver->owner);
+	iio_dmaengine_buffer_free(buffer);
 }
 
 static const struct regmap_config axi_adc_regmap_config = {
@@ -344,45 +158,46 @@ static const struct regmap_config axi_adc_regmap_config = {
 	.max_register = 0x0800,
 };
 
+static const struct iio_backend_ops adi_axi_adc_generic = {
+	.enable = axi_adc_enable,
+	.disable = axi_adc_disable,
+	.data_format_set = axi_adc_data_format_set,
+	.chan_enable = axi_adc_chan_enable,
+	.chan_disable = axi_adc_chan_disable,
+	.request_buffer = axi_adc_request_buffer,
+	.free_buffer = axi_adc_free_buffer,
+};
+
 static int adi_axi_adc_probe(struct platform_device *pdev)
 {
-	struct adi_axi_adc_conv *conv;
-	struct iio_dev *indio_dev;
-	struct adi_axi_adc_client *cl;
 	struct adi_axi_adc_state *st;
 	void __iomem *base;
-	unsigned int ver;
+	unsigned int ver, *expected_ver;
 	int ret;
 
-	cl = adi_axi_adc_attach_client(&pdev->dev);
-	if (IS_ERR(cl))
-		return PTR_ERR(cl);
-
-	ret = devm_add_action_or_reset(&pdev->dev, adi_axi_adc_cleanup, cl);
-	if (ret)
-		return ret;
-
-	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*st));
-	if (indio_dev == NULL)
+	st = devm_kzalloc(&pdev->dev, sizeof(*st), GFP_KERNEL);
+	if (!st)
 		return -ENOMEM;
 
-	st = iio_priv(indio_dev);
-	st->client = cl;
-	cl->state = st;
-	mutex_init(&st->lock);
-
 	base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(base))
 		return PTR_ERR(base);
 
+	st->dev = &pdev->dev;
 	st->regmap = devm_regmap_init_mmio(&pdev->dev, base,
 					   &axi_adc_regmap_config);
 	if (IS_ERR(st->regmap))
 		return PTR_ERR(st->regmap);
 
-	conv = &st->client->conv;
+	expected_ver = (unsigned int *)device_get_match_data(&pdev->dev);
+	if (!expected_ver)
+		return -ENODEV;
 
-	ret = axi_adc_reset(st);
+	/*
+	 * Force disable the core. Up to the frontend to enable us. And we can
+	 * still read/write registers...
+	 */
+	ret = regmap_write(st->regmap, ADI_AXI_REG_RSTN, 0);
 	if (ret)
 		return ret;
 
@@ -390,37 +205,23 @@ static int adi_axi_adc_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	if (cl->info->version > ver) {
+	if (*expected_ver > ver) {
 		dev_err(&pdev->dev,
 			"IP core version is too old. Expected %d.%.2d.%c, Reported %d.%.2d.%c\n",
-			ADI_AXI_PCORE_VER_MAJOR(cl->info->version),
-			ADI_AXI_PCORE_VER_MINOR(cl->info->version),
-			ADI_AXI_PCORE_VER_PATCH(cl->info->version),
+			ADI_AXI_PCORE_VER_MAJOR(*expected_ver),
+			ADI_AXI_PCORE_VER_MINOR(*expected_ver),
+			ADI_AXI_PCORE_VER_PATCH(*expected_ver),
 			ADI_AXI_PCORE_VER_MAJOR(ver),
 			ADI_AXI_PCORE_VER_MINOR(ver),
 			ADI_AXI_PCORE_VER_PATCH(ver));
 		return -ENODEV;
 	}
 
-	indio_dev->info = &adi_axi_adc_info;
-	indio_dev->name = "adi-axi-adc";
-	indio_dev->modes = INDIO_DIRECT_MODE;
-	indio_dev->num_channels = conv->chip_info->num_channels;
-	indio_dev->channels = conv->chip_info->channels;
-
-	ret = adi_axi_adc_config_dma_buffer(&pdev->dev, indio_dev);
+	ret = devm_iio_backend_register(&pdev->dev, &adi_axi_adc_generic, st);
 	if (ret)
 		return ret;
 
-	ret = adi_axi_adc_setup_channels(&pdev->dev, st);
-	if (ret)
-		return ret;
-
-	ret = devm_iio_device_register(&pdev->dev, indio_dev);
-	if (ret)
-		return ret;
-
-	dev_info(&pdev->dev, "AXI ADC IP core (%d.%.2d.%c) probed\n",
+	dev_info(&pdev->dev, "AXI ADC IP core (%d.%.2d.%d) probed\n",
 		 ADI_AXI_PCORE_VER_MAJOR(ver),
 		 ADI_AXI_PCORE_VER_MINOR(ver),
 		 ADI_AXI_PCORE_VER_PATCH(ver));
@@ -428,6 +229,8 @@ static int adi_axi_adc_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static unsigned int adi_axi_adc_10_0_a_info = ADI_AXI_PCORE_VER(10, 0, 'a');
+
 /* Match table for of_platform binding */
 static const struct of_device_id adi_axi_adc_of_match[] = {
 	{ .compatible = "adi,axi-adc-10.0.a", .data = &adi_axi_adc_10_0_a_info },
diff --git a/include/linux/iio/adc/adi-axi-adc.h b/include/linux/iio/adc/adi-axi-adc.h
deleted file mode 100644
index b7904992d561..000000000000
--- a/include/linux/iio/adc/adi-axi-adc.h
+++ /dev/null
@@ -1,68 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Analog Devices Generic AXI ADC IP core driver/library
- * Link: https://wiki.analog.com/resources/fpga/docs/axi_adc_ip
- *
- * Copyright 2012-2020 Analog Devices Inc.
- */
-#ifndef __ADI_AXI_ADC_H__
-#define __ADI_AXI_ADC_H__
-
-struct device;
-struct iio_chan_spec;
-
-/**
- * struct adi_axi_adc_chip_info - Chip specific information
- * @name		Chip name
- * @id			Chip ID (usually product ID)
- * @channels		Channel specifications of type @struct iio_chan_spec
- * @num_channels	Number of @channels
- * @scale_table		Supported scales by the chip; tuples of 2 ints
- * @num_scales		Number of scales in the table
- * @max_rate		Maximum sampling rate supported by the device
- */
-struct adi_axi_adc_chip_info {
-	const char			*name;
-	unsigned int			id;
-
-	const struct iio_chan_spec	*channels;
-	unsigned int			num_channels;
-
-	const unsigned int		(*scale_table)[2];
-	int				num_scales;
-
-	unsigned long			max_rate;
-};
-
-/**
- * struct adi_axi_adc_conv - data of the ADC attached to the AXI ADC
- * @chip_info		chip info details for the client ADC
- * @preenable_setup	op to run in the client before enabling the AXI ADC
- * @reg_access		IIO debugfs_reg_access hook for the client ADC
- * @read_raw		IIO read_raw hook for the client ADC
- * @write_raw		IIO write_raw hook for the client ADC
- * @read_avail		IIO read_avail hook for the client ADC
- */
-struct adi_axi_adc_conv {
-	const struct adi_axi_adc_chip_info		*chip_info;
-
-	int (*preenable_setup)(struct adi_axi_adc_conv *conv);
-	int (*reg_access)(struct adi_axi_adc_conv *conv, unsigned int reg,
-			  unsigned int writeval, unsigned int *readval);
-	int (*read_raw)(struct adi_axi_adc_conv *conv,
-			struct iio_chan_spec const *chan,
-			int *val, int *val2, long mask);
-	int (*write_raw)(struct adi_axi_adc_conv *conv,
-			 struct iio_chan_spec const *chan,
-			 int val, int val2, long mask);
-	int (*read_avail)(struct adi_axi_adc_conv *conv,
-			  struct iio_chan_spec const *chan,
-			  const int **val, int *type, int *length, long mask);
-};
-
-struct adi_axi_adc_conv *devm_adi_axi_adc_conv_register(struct device *dev,
-							size_t sizeof_priv);
-
-void *adi_axi_adc_conv_priv(struct adi_axi_adc_conv *conv);
-
-#endif

-- 
2.43.0

Re: [PATCH v2 0/8] iio: add new backend framework

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 5555 bytes --]

On Fri, Dec 08, 2023 at 04:14:07PM +0100, Nuno Sa via B4 Relay wrote:
> This series depends on [1] and it only build on top of it. The point is
> to already speed up the reviewing of the framework. That obviously means
> that all those pacthes were dropped in v2.
> 
> v1:
>  https://lore.kernel.org/linux-iio/20231204144925.4fe9922f@jic23-huawei/T/#m222f5175273b81dbfe40b7f0daffcdc67d6cb8ff
> 
> Changes in v2:
>  - Patch 1-2 and 5
>    * new patches.
>  - Patch 6:
>    * Fixed some docs failures;
>    * Fixed a legacy 'conv' name in one of the function parameters;
>    * Added .request_buffer() and .free_buffer() ops;
>    * Refactored the helper macros;
>    * Added Olivier as Reviewer.
>  - Patch 7:
>    * Use new devm_iio_backend_request_buffer().
>  - Patch 8:
>    * Implement new .request_buffer() and .free_buffer() ops;
> 
> Also would like to mention that in v2 I'm experimenting in having the
> DMA on the backend device (as discussed with David in v1). Does not look
> to bad but as I said before, I'm not seeing a big issue if we end up
> having the buffer allocation in the frontend.
> 
> For the bindings folks:
> 
> I'm introducing a new io-backends property in the ad9467 bindings but I'm
> not sure this is the way to do it. Ideally that new property become a
> generic schema and I'm guessing I should send a PULL to?
> 
> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/iio/iio-consumer.yaml

That seems like the right thing to do to me, depending on how widespread
the use of these backends might be. What is seemingly missing though,
from this cover and from the bindings patch in the series in particular,
is an explanation of what the "iio-backends" hardware actually is.

There is some text below, but it does not seem complete to me. Is the
idea that this "backend" is shared between multiple frontend consumers?
The one example is described as being "highly focused on ADI usecases"

Thanks,
Conor.

> 
> (Jonathan, if you think that's not the right place, shout now :))
> 
> I'm also deprecating 'adi,adc-dev' as it is not relevant anymore. In the
> driver code, we are actually breaking ABI but I'm taking a more
> conservative approach in the bindings. Ideally I would also remove it in
> the bindings :).
>  
> 
> As requested here we have a small diagram that illustrated on e typical
> usage of the new framework:
> 
>                                            -------------------------------------------------------
>  ------------------                        | -----------         ------------      -------  FPGA |
>  |     ADC        |------------------------| | AXI ADC |---------| DMA CORE |------| RAM |       |
>  | (Frontend/IIO) | Serial Data (eg: LVDS) | |(backend)|---------|          |------|     |       |
>  |                |------------------------| -----------         ------------      -------       |
>  ------------------                        -------------------------------------------------------
>  
> The above is highly focused on ADI usecases. But one can see the idea...
> The frontend is the real converter and is the one registering and
> handling all the IIO interfaces. Such a device can then connect to a
> backend device for further services/configurations. In the above
> example, the backend device is an high speed core capable of handling
> the high sample rate of these ADCs so that it can push that data further
> in the pipeline (typically a DMA core) so the user can process the
> samples with minimal losses.
> 
> Jonathan, I was also tempted in including the diagram in the source
> file. Would that be a good idea?
> 
> [1]: https://lore.kernel.org/linux-iio/20231207-iio-backend-prep-v2-0-a4a33bc4d70e@analog.com
> 
> ---
> Nuno Sa (7):
>       dt-bindings: adc: ad9467: document io-backend property
>       dt-bindings: adc: axi-adc: deprecate 'adi,adc-dev'
>       driver: core: allow modifying device_links flags
>       iio: buffer-dmaengine: export buffer alloc and free functions
>       iio: add the IIO backend framework
>       iio: adc: ad9467: convert to backend framework
>       iio: adc: adi-axi-adc: move to backend framework
> 
> Olivier Moysan (1):
>       of: property: add device link support for io-backends
> 
>  .../devicetree/bindings/iio/adc/adi,ad9467.yaml    |   5 +
>  .../devicetree/bindings/iio/adc/adi,axi-adc.yaml   |   4 +-
>  MAINTAINERS                                        |   8 +
>  drivers/base/core.c                                |  14 +-
>  drivers/iio/Kconfig                                |   5 +
>  drivers/iio/Makefile                               |   1 +
>  drivers/iio/adc/Kconfig                            |   3 +-
>  drivers/iio/adc/ad9467.c                           | 242 +++++++------
>  drivers/iio/adc/adi-axi-adc.c                      | 379 +++++---------------
>  drivers/iio/buffer/industrialio-buffer-dmaengine.c |   6 +-
>  drivers/iio/industrialio-backend.c                 | 386 +++++++++++++++++++++
>  drivers/of/property.c                              |   2 +
>  include/linux/iio/adc/adi-axi-adc.h                |  68 ----
>  include/linux/iio/backend.h                        |  68 ++++
>  include/linux/iio/buffer-dmaengine.h               |   4 +-
>  15 files changed, 727 insertions(+), 468 deletions(-)
> ---
> base-commit: 330c0f834ccbdbe6a89da475cb1c56893f3a8363
> change-id: 20231120-dev-iio-backend-d14b473a1d9f
> --
> 
> Thanks!
> - Nuno Sá
> 

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Re: [PATCH v2 0/8] iio: add new backend framework

[Nuno Sá]

On Fri, 2023-12-08 at 15:30 +0000, Conor Dooley wrote:
> On Fri, Dec 08, 2023 at 04:14:07PM +0100, Nuno Sa via B4 Relay wrote:
> > This series depends on [1] and it only build on top of it. The point is
> > to already speed up the reviewing of the framework. That obviously means
> > that all those pacthes were dropped in v2.
> > 
> > v1:
> >  
> > https://lore.kernel.org/linux-iio/20231204144925.4fe9922f@jic23-huawei/T/#m222f517
> > 5273b81dbfe40b7f0daffcdc67d6cb8ff
> > 
> > Changes in v2:
> >  - Patch 1-2 and 5
> >    * new patches.
> >  - Patch 6:
> >    * Fixed some docs failures;
> >    * Fixed a legacy 'conv' name in one of the function parameters;
> >    * Added .request_buffer() and .free_buffer() ops;
> >    * Refactored the helper macros;
> >    * Added Olivier as Reviewer.
> >  - Patch 7:
> >    * Use new devm_iio_backend_request_buffer().
> >  - Patch 8:
> >    * Implement new .request_buffer() and .free_buffer() ops;
> > 
> > Also would like to mention that in v2 I'm experimenting in having the
> > DMA on the backend device (as discussed with David in v1). Does not look
> > to bad but as I said before, I'm not seeing a big issue if we end up
> > having the buffer allocation in the frontend.
> > 
> > For the bindings folks:
> > 
> > I'm introducing a new io-backends property in the ad9467 bindings but I'm
> > not sure this is the way to do it. Ideally that new property become a
> > generic schema and I'm guessing I should send a PULL to?
> > 
> > https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/iio/iio-consumer.yaml
> 
> That seems like the right thing to do to me, depending on how widespread
> the use of these backends might be. What is seemingly missing though,
> from this cover and from the bindings patch in the series in particular,
> is an explanation of what the "iio-backends" hardware actually is.
> 

Yeah, sorry about the bindings patch but I was already with the feeling that a PR in
devicetree-org to be the right place. I'll be adding more drivers needing that
property and STM also wants make use this.

I'll improve on the explanation and send a PR for a generic schema.

> There is some text below, but it does not seem complete to me. Is the
> idea that this "backend" is shared between multiple frontend consumers?
> The one example is described as being "highly focused on ADI usecases"
> 

For now it cannot really be shared. The code is not prepared for it (we would need to
keep enable/disable counters etc...). For now, I'm just adding the simpler cases of
1:1 and 1:n (1 frontend for multiple backends). Internally we do have 1:n designs
that I definitely want (in time) to bring upstream.

That said, having a usecase for it in the future, it is something that can be added,
yes...

Thanks for the feedback!
- Nuno Sá
> 

Re: [PATCH v2 0/8] iio: add new backend framework

[Conor Dooley]

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On Sat, Dec 09, 2023 at 03:32:33PM +0100, Nuno Sá wrote:
> On Fri, 2023-12-08 at 15:30 +0000, Conor Dooley wrote:
> > On Fri, Dec 08, 2023 at 04:14:07PM +0100, Nuno Sa via B4 Relay wrote:
> > > This series depends on [1] and it only build on top of it. The point is
> > > to already speed up the reviewing of the framework. That obviously means
> > > that all those pacthes were dropped in v2.
> > > 
> > > v1:
> > >  
> > > https://lore.kernel.org/linux-iio/20231204144925.4fe9922f@jic23-huawei/T/#m222f517
> > > 5273b81dbfe40b7f0daffcdc67d6cb8ff
> > > 
> > > Changes in v2:
> > >  - Patch 1-2 and 5
> > >    * new patches.
> > >  - Patch 6:
> > >    * Fixed some docs failures;
> > >    * Fixed a legacy 'conv' name in one of the function parameters;
> > >    * Added .request_buffer() and .free_buffer() ops;
> > >    * Refactored the helper macros;
> > >    * Added Olivier as Reviewer.
> > >  - Patch 7:
> > >    * Use new devm_iio_backend_request_buffer().
> > >  - Patch 8:
> > >    * Implement new .request_buffer() and .free_buffer() ops;
> > > 
> > > Also would like to mention that in v2 I'm experimenting in having the
> > > DMA on the backend device (as discussed with David in v1). Does not look
> > > to bad but as I said before, I'm not seeing a big issue if we end up
> > > having the buffer allocation in the frontend.
> > > 
> > > For the bindings folks:
> > > 
> > > I'm introducing a new io-backends property in the ad9467 bindings but I'm
> > > not sure this is the way to do it. Ideally that new property become a
> > > generic schema and I'm guessing I should send a PULL to?
> > > 
> > > https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/iio/iio-consumer.yaml
> > 
> > That seems like the right thing to do to me, depending on how widespread
> > the use of these backends might be. What is seemingly missing though,
> > from this cover and from the bindings patch in the series in particular,
> > is an explanation of what the "iio-backends" hardware actually is.
> > 
> 
> Yeah, sorry about the bindings patch but I was already with the feeling that a PR in
> devicetree-org to be the right place. I'll be adding more drivers needing that
> property and STM also wants make use this.
> 
> I'll improve on the explanation and send a PR for a generic schema.
> 
> > There is some text below, but it does not seem complete to me. Is the
> > idea that this "backend" is shared between multiple frontend consumers?
> > The one example is described as being "highly focused on ADI usecases"
> > 
> 
> For now it cannot really be shared. The code is not prepared for it (we would need to
> keep enable/disable counters etc...). For now, I'm just adding the simpler cases of
> 1:1 and 1:n (1 frontend for multiple backends). Internally we do have 1:n designs
> that I definitely want (in time) to bring upstream.

TBH, I am not really interested in whether or not the drivers support it
at the moment, it just be great if the explanation of how these backends
work (the hardware, not the linux implementation) included that detail.
> 
> That said, having a usecase for it in the future, it is something that can be added,
> yes...
> 
> Thanks for the feedback!
> - Nuno Sá
> > 
> 

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