[PATCH v5 0/8] iio: add new backend framework

[PATCH v5 0/8] iio: add new backend framework

[Nuno Sa via B4 Relay]

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

v2:
 https://lore.kernel.org/r/20231208-dev-iio-backend-v2-0-5450951895e1@analog.com

v3:
 https://lore.kernel.org/linux-iio/20231213-dev-iio-backend-v3-0-bb9f12a5c6dc@analog.com/

v4:
 https://lore.kernel.org/r/20231220-iio-backend-v4-0-998e9148b692@analog.com

Changes in v5:
 - Patch 2
  * Update commit subject and message;
  * Add '#io-backends-cells' property.
 - Patch 4
  * Also support '#io-backends-cells'.
 - Patch 6
  * Improve Kconfig help message;
  * Only use device_links to control backends access. With this, we can remove
    all the mutex + sync logic as we are now guaranteed that a frontend cannot
    be up and running if one of the backends is gone.
  * Error out if we can't create the device_link (so we can guarantee the above).
  * Improve docs for __devm_iio_backend_get_from_fwnode_lookup();
  * Add a __ prefix to devm_iio_backend_get_from_fwnode_lookup() so it's clear
    that API should not be used (or used with care);
  * Drop devm_iio_backend_get_optional();
  * remove unneeded headers.
 - Patch 7
  * Handle the optional backend in the driver.

The biggest difference is that the backend @ops pointer handling to
reason about the backend existence is gone. Now, we rely on device_links
as that makes sure all consumers (in the link) are unbound before the
provider. Hence, the frontend is guaranteed to be unbound if any of the
backends is gone. That simplifies things a lot...

Keeping the block diagram  so we don't have to follow links
to check one of the typical setups.

                                           -------------------------------------------------------
 ------------------                        | -----------         ------------      -------  FPGA |
 |     ADC        |------------------------| | AXI ADC |---------| DMA CORE |------| RAM |       |
 | (Frontend/IIO) | Serial Data (eg: LVDS) | |(backend)|---------|          |------|     |       |
 |                |------------------------| -----------         ------------      -------       |
 ------------------                        -------------------------------------------------------

---
Nuno Sa (7):
      dt-bindings: adc: ad9467: add new io-backend property
      dt-bindings: adc: axi-adc: update bindings for backend framework
      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    |   4 +
 .../devicetree/bindings/iio/adc/adi,axi-adc.yaml   |   7 +-
 MAINTAINERS                                        |   8 +
 drivers/base/core.c                                |  14 +-
 drivers/iio/Kconfig                                |   9 +
 drivers/iio/Makefile                               |   1 +
 drivers/iio/adc/Kconfig                            |   4 +-
 drivers/iio/adc/ad9467.c                           | 283 +++++++++-----
 drivers/iio/adc/adi-axi-adc.c                      | 381 +++++--------------
 drivers/iio/buffer/industrialio-buffer-dmaengine.c |   8 +-
 drivers/iio/industrialio-backend.c                 | 411 +++++++++++++++++++++
 drivers/of/property.c                              |   2 +
 include/linux/iio/adc/adi-axi-adc.h                |  68 ----
 include/linux/iio/backend.h                        |  73 ++++
 include/linux/iio/buffer-dmaengine.h               |   3 +
 15 files changed, 806 insertions(+), 470 deletions(-)
---
base-commit: 3f4525f924e21d4f532517b17a20ffa5df7c0db7
change-id: 20231219-iio-backend-a3dc1a6a7a58
--

Thanks!
- Nuno Sá

[PATCH v5 1/8] dt-bindings: adc: ad9467: add new io-backend property

[Nuno Sa via B4 Relay]

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

The ad9467 will make use of the new IIO backend framework which is a
provider - consumer interface where IIO backends provide services to
consumers. As such, and being this device a consumer,  add the new
generic io-backend property to the bindings.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
 Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml
index 7aa748d6b7a0..eecd5fbab695 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad9467.yaml
@@ -44,6 +44,9 @@ properties:
       Pin that controls the powerdown mode of the device.
     maxItems: 1
 
+  io-backends:
+    maxItems: 1
+
   reset-gpios:
     description:
       Reset pin for the device.
@@ -68,6 +71,7 @@ examples:
             reg = <0>;
             clocks = <&adc_clk>;
             clock-names = "adc-clk";
+            io-backends = <&iio_backend>;
         };
     };
 ...

-- 
2.43.0

[PATCH v5 2/8] dt-bindings: adc: axi-adc: update bindings for backend framework

[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.

The reason why it's being deprecated is because the axi-adc CORE is now
an IIO service provider hardware (IIO backends) for consumers to make use
of. Before, the logic with 'adi,adc-dev' was the opposite (it was kind
of consumer referencing other nodes/devices) and that proved to be wrong
and to not scale.

Now, IIO consumers of this hardware are expected to reference it using the
io-backends property. Hence, the new '#io-backend-cells' is being added
so the device is easily identified as a provider.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
 Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml | 7 ++++---
 1 file changed, 4 insertions(+), 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..dc7b14546afb 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml
@@ -39,12 +39,15 @@ properties:
     $ref: /schemas/types.yaml#/definitions/phandle
     description:
       A reference to a the actual ADC to which this FPGA ADC interfaces to.
+    deprecated: true
+
+  '#io-backends-cells'
+    const: 0
 
 required:
   - compatible
   - dmas
   - reg
-  - adi,adc-dev
 
 additionalProperties: false
 
@@ -55,7 +58,5 @@ examples:
         reg = <0x44a00000 0x10000>;
         dmas = <&rx_dma 0>;
         dma-names = "rx";
-
-        adi,adc-dev = <&spi_adc>;
     };
 ...

-- 
2.43.0

Re: [PATCH v5 2/8] dt-bindings: adc: axi-adc: update bindings for backend framework

[Rob Herring]

On Fri, 12 Jan 2024 17:40:16 +0100, Nuno Sa wrote:
> 'adi,adc-dev' is now deprecated and must not be used anymore. Hence,
> also remove it from being required.
> 
> The reason why it's being deprecated is because the axi-adc CORE is now
> an IIO service provider hardware (IIO backends) for consumers to make use
> of. Before, the logic with 'adi,adc-dev' was the opposite (it was kind
> of consumer referencing other nodes/devices) and that proved to be wrong
> and to not scale.
> 
> Now, IIO consumers of this hardware are expected to reference it using the
> io-backends property. Hence, the new '#io-backend-cells' is being added
> so the device is easily identified as a provider.
> 
> Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> ---
>  Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:
./Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml:45:5: [error] syntax error: could not find expected ':' (syntax)

dtschema/dtc warnings/errors:
make[2]: *** Deleting file 'Documentation/devicetree/bindings/iio/adc/adi,axi-adc.example.dts'
Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml:45:5: could not find expected ':'
make[2]: *** [Documentation/devicetree/bindings/Makefile:26: Documentation/devicetree/bindings/iio/adc/adi,axi-adc.example.dts] Error 1
make[2]: *** Waiting for unfinished jobs....
./Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml:45:5: could not find expected ':'
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/iio/adc/adi,axi-adc.yaml: ignoring, error parsing file
make[1]: *** [/builds/robherring/dt-review-ci/linux/Makefile:1424: dt_binding_check] Error 2
make: *** [Makefile:234: __sub-make] Error 2

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20240112-iio-backend-v5-2-bdecad041ab4@analog.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

[PATCH v5 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

[PATCH v5 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>
Acked-by: Rob Herring <robh@kernel.org>
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..c5909ffd93f2 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", "#io-backends-cells")
 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 v5 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).

While at it, namespace the buffer-dmaengine exports and update the
current user of these buffers.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
 drivers/iio/adc/adi-axi-adc.c                      | 1 +
 drivers/iio/buffer/industrialio-buffer-dmaengine.c | 8 +++++---
 include/linux/iio/buffer-dmaengine.h               | 3 +++
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
index c247ff1541d2..0f21d1d98b9f 100644
--- a/drivers/iio/adc/adi-axi-adc.c
+++ b/drivers/iio/adc/adi-axi-adc.c
@@ -447,3 +447,4 @@ module_platform_driver(adi_axi_adc_driver);
 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
 MODULE_DESCRIPTION("Analog Devices Generic AXI ADC IP core driver");
 MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS(IIO_DMAENGINE_BUFFER);
diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
index 5f85ba38e6f6..0d53c0a07b0d 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_NS_GPL(iio_dmaengine_buffer_alloc, IIO_DMAENGINE_BUFFER);
 
 /**
  * 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_NS_GPL(iio_dmaengine_buffer_free, IIO_DMAENGINE_BUFFER);
 
 static void __devm_iio_dmaengine_buffer_free(void *buffer)
 {
@@ -288,7 +290,7 @@ int devm_iio_dmaengine_buffer_setup(struct device *dev,
 
 	return iio_device_attach_buffer(indio_dev, buffer);
 }
-EXPORT_SYMBOL_GPL(devm_iio_dmaengine_buffer_setup);
+EXPORT_SYMBOL_NS_GPL(devm_iio_dmaengine_buffer_setup, IIO_DMAENGINE_BUFFER);
 
 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 MODULE_DESCRIPTION("DMA buffer for the IIO framework");
diff --git a/include/linux/iio/buffer-dmaengine.h b/include/linux/iio/buffer-dmaengine.h
index 5c355be89814..cbb8ba957fad 100644
--- a/include/linux/iio/buffer-dmaengine.h
+++ b/include/linux/iio/buffer-dmaengine.h
@@ -10,6 +10,9 @@
 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);

-- 
2.43.0

[PATCH v5 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                |   9 +
 drivers/iio/Makefile               |   1 +
 drivers/iio/industrialio-backend.c | 411 +++++++++++++++++++++++++++++++++++++
 include/linux/iio/backend.h        |  73 +++++++
 5 files changed, 502 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 0764fafce958..100aef8adc26 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10302,6 +10302,14 @@ 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..9c351ffc7bed 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -71,6 +71,15 @@ 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. The typical
+	  architecture that can make use of this framework is to have one
+	  device as the frontend device which can be "linked" against one or
+	  multiple backend devices. The framework then makes it easy to get
+	  and control such backend 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..994bc68c2679
--- /dev/null
+++ b/drivers/iio/industrialio-backend.c
@@ -0,0 +1,411 @@
+// 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/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;
+};
+
+/*
+ * 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 call backend ops. Makes sure the option is supported
+ */
+#define iio_backend_check_op(back, op) ({ \
+	struct iio_backend *____back = back;				\
+	int ____ret = 0;						\
+									\
+	if (!____back->ops->op)						\
+		____ret = -EOPNOTSUPP;					\
+									\
+	____ret;							\
+})
+
+#define iio_backend_op_call(back, op, args...) ({		\
+	struct iio_backend *__back = back;			\
+	int __ret;						\
+								\
+	__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;						\
+								\
+	__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;						\
+								\
+	__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_NS_GPL(iio_backend_chan_enable, IIO_BACKEND);
+
+/**
+ * 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_NS_GPL(iio_backend_chan_disable, IIO_BACKEND);
+
+/**
+ * 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_NS_GPL(iio_backend_enable, IIO_BACKEND);
+
+/**
+ * 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_NS_GPL(iio_backend_disable, IIO_BACKEND);
+
+/**
+ * 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_NS_GPL(iio_backend_data_format_set, IIO_BACKEND);
+
+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);
+
+	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_NS_GPL(devm_iio_backend_request_buffer, IIO_BACKEND);
+
+static void iio_backend_release(void *arg)
+{
+	struct iio_backend *back = arg;
+
+	module_put(back->owner);
+}
+
+static int __devm_iio_backend_get(struct device *dev, struct iio_backend *back)
+{
+	struct device_link *link;
+	int ret;
+
+	/*
+	 * Make sure the provider cannot be unloaded before the consumer module.
+	 * Note that device_links would still guarantee that nothing is
+	 * accessible (and breaks) but this makes it explicit that the consumer
+	 * module must be also unloaded.
+	 */
+	if (!try_module_get(back->owner)) {
+		pr_err("%s: Cannot get module reference\n", dev_name(dev));
+		return -ENODEV;
+	}
+
+	ret = devm_add_action_or_reset(dev, iio_backend_release, back);
+	if (ret)
+		return ret;
+
+	link = device_link_add(dev, back->dev, DL_FLAG_AUTOREMOVE_CONSUMER);
+	if (!link) {
+		pr_err("%s: Could not link to supplier(%s)\n", dev_name(dev),
+		       dev_name(back->dev));
+		return -EINVAL;
+	}
+
+	pr_debug("%s: Found backend(%s) device\n", dev_name(dev),
+		 dev_name(back->dev));
+
+	return 0;
+}
+
+/**
+ * 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)) {
+		/* not an error if optional */
+		pr_debug("%s: Cannot get Firmware reference\n", dev_name(dev));
+		return ERR_CAST(fwnode);
+	}
+
+	guard(mutex)(&iio_back_lock);
+	list_for_each_entry(back, &iio_back_list, entry) {
+		if (!device_match_fwnode(back->dev, fwnode))
+			continue;
+
+		fwnode_handle_put(fwnode);
+		ret = __devm_iio_backend_get(dev, back);
+		if (ret)
+			return ERR_PTR(ret);
+
+		return back;
+	}
+
+	fwnode_handle_put(fwnode);
+	return ERR_PTR(-EPROBE_DEFER);
+}
+EXPORT_SYMBOL_NS_GPL(devm_iio_backend_get, IIO_BACKEND);
+
+/**
+ * devm_iio_backend_get_from_fwnode_lookup
+ * @dev:	Device where to bind the backend lifetime.
+ * @fwnode:	Firmware node of the backend device.
+ *
+ * Search the backend list for a device matching @fwnode.
+ * This API should not be used and it's only present for preventing the first
+ * user of this framework to break it's DT ABI.
+ *
+ * RETURNS:
+ * A backend pointer, negative error pointer otherwise.
+ */
+struct iio_backend *
+__devm_iio_backend_get_from_fwnode_lookup(struct device *dev,
+					  struct fwnode_handle *fwnode)
+{
+	struct iio_backend *back;
+	int ret;
+
+	guard(mutex)(&iio_back_lock);
+	list_for_each_entry(back, &iio_back_list, entry) {
+		if (!device_match_fwnode(back->dev, fwnode))
+			continue;
+
+		ret = __devm_iio_backend_get(dev, back);
+		if (ret)
+			return ERR_PTR(ret);
+
+		return back;
+	}
+
+	return ERR_PTR(-EPROBE_DEFER);
+}
+EXPORT_SYMBOL_NS_GPL(__devm_iio_backend_get_from_fwnode_lookup, IIO_BACKEND);
+
+/**
+ * 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_NS_GPL(iio_backend_get_priv, IIO_BACKEND);
+
+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);
+}
+
+/**
+ * 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) {
+		pr_err("%s: No backend ops or private data given\n",
+		       dev_name(dev));
+		return -EINVAL;
+	}
+
+	/*
+	 * Through device_links, we guarantee that a frontend device cannot be
+	 * bound/exist if the backend driver is not around. Hence, we can bind
+	 * the backend object lifetime with the device being passed since
+	 * removing it will torn the frontend down.
+	 */
+	back = devm_kzalloc(dev, sizeof(*back), GFP_KERNEL);
+	if (!back)
+		return -ENOMEM;
+
+	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_NS_GPL(devm_iio_backend_register, IIO_BACKEND);
+
+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..b7c2c2366403
--- /dev/null
+++ b/include/linux/iio/backend.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _IIO_BACKEND_H_
+#define _IIO_BACKEND_H_
+
+#include <linux/types.h>
+
+struct fwnode_handle;
+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);
+struct iio_backend *
+__devm_iio_backend_get_from_fwnode_lookup(struct device *dev,
+					  struct fwnode_handle *fwnode);
+
+int devm_iio_backend_register(struct device *dev,
+			      const struct iio_backend_ops *ops, void *priv);
+
+#endif

-- 
2.43.0

Re: [PATCH v5 6/8] iio: add the IIO backend framework

[Jonathan Cameron]

On Fri, 12 Jan 2024 17:40:20 +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>

A few minor comments inline.

...

> diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
> new file mode 100644
> index 000000000000..994bc68c2679
> --- /dev/null
> +++ b/drivers/iio/industrialio-backend.c
> @@ -0,0 +1,411 @@

...

> +
> +/*
> + * Helper struct for requesting buffers. Allows for multiple buffers per
> + * backend.
Only seems to be used to ensure we have all the data needed to free it...
So comment seems less than obviously connected to that.
> + */
> +struct iio_backend_buffer_pair {
> +	struct iio_backend *back;
> +	struct iio_buffer *buffer;
> +};
> +

> +/**
> + * 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_NS_GPL(iio_backend_chan_enable, IIO_BACKEND);
> +
> +/**
> + * iio_backend_chan_disable - Disable a backend channel.
> + * @back:	Backend device.
> + * @chan:	Channel number.
Would be good to be consistent on . or not.
> + *
> + * 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_NS_GPL(iio_backend_chan_disable, IIO_BACKEND);
> +
> +/**
> + * iio_backend_chan_enable - Enable the backend.
> + * @back:	Backend device



...


> +/**
> + * devm_iio_backend_get_from_fwnode_lookup

Not valid kernel doc + name is wrong.  Make sure you run
the kernel-doc script over this and fix any errors or warnings
reported.

> + * @dev:	Device where to bind the backend lifetime.
> + * @fwnode:	Firmware node of the backend device.
> + *
> + * Search the backend list for a device matching @fwnode.
> + * This API should not be used and it's only present for preventing the first
> + * user of this framework to break it's DT ABI.
> + *
> + * RETURNS:
> + * A backend pointer, negative error pointer otherwise.
> + */
> +struct iio_backend *
> +__devm_iio_backend_get_from_fwnode_lookup(struct device *dev,
> +					  struct fwnode_handle *fwnode)
> +{
> +	struct iio_backend *back;
> +	int ret;
> +
> +	guard(mutex)(&iio_back_lock);
> +	list_for_each_entry(back, &iio_back_list, entry) {
> +		if (!device_match_fwnode(back->dev, fwnode))
> +			continue;
> +
> +		ret = __devm_iio_backend_get(dev, back);
> +		if (ret)
> +			return ERR_PTR(ret);
> +
> +		return back;
> +	}
> +
> +	return ERR_PTR(-EPROBE_DEFER);
> +}
> +EXPORT_SYMBOL_NS_GPL(__devm_iio_backend_get_from_fwnode_lookup, IIO_BACKEND);
>


> +/**
> + * 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.

It's unusual to 'insist' on the private data.
Whilst it's highly likely it will always be there from a core point of view
we don't mind it being NULL.  This is different from the ops as we want
to be able to call those without checking they are there.

> + *
> + * 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) {

> +		pr_err("%s: No backend ops or private data given\n",
> +		       dev_name(dev));
> +		return -EINVAL;
> +	}
> +
> +	/*
> +	 * Through device_links, we guarantee that a frontend device cannot be
> +	 * bound/exist if the backend driver is not around. Hence, we can bind
> +	 * the backend object lifetime with the device being passed since
> +	 * removing it will torn the frontend down.

"will have torn" or "will tear the"

> +	 */
> +	back = devm_kzalloc(dev, sizeof(*back), GFP_KERNEL);
> +	if (!back)
> +		return -ENOMEM;
> +
> +	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_NS_GPL(devm_iio_backend_register, IIO_BACKEND);
> +
> +MODULE_AUTHOR("Nuno Sa <nuno.sa@analog.com>");
> +MODULE_DESCRIPTION("Framework to handle complex IIO aggregate devices");
> +MODULE_LICENSE("GPL");

Re: [PATCH v5 6/8] iio: add the IIO backend framework

[Nuno Sá]

On Sat, 2024-01-13 at 17:22 +0000, Jonathan Cameron wrote:
> On Fri, 12 Jan 2024 17:40:20 +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>
> 
> A few minor comments inline.
> 
> ...
> 
> > diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-
> > backend.c
> > new file mode 100644
> > index 000000000000..994bc68c2679
> > --- /dev/null
> > +++ b/drivers/iio/industrialio-backend.c
> > @@ -0,0 +1,411 @@
> 
> ...
> 
> > +
> > +/*
> > + * Helper struct for requesting buffers. Allows for multiple buffers per
> > + * backend.
> Only seems to be used to ensure we have all the data needed to free it...
> So comment seems less than obviously connected to that.

I'll update the comment...

> > + */
> > +struct iio_backend_buffer_pair {
> > +	struct iio_backend *back;
> > +	struct iio_buffer *buffer;
> > +};
> > +
> 
> > +/**
> > + * 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_NS_GPL(iio_backend_chan_enable, IIO_BACKEND);
> > +
> > +/**
> > + * iio_backend_chan_disable - Disable a backend channel.
> > + * @back:	Backend device.
> > + * @chan:	Channel number.
> Would be good to be consistent on . or not.

Agreed.

> > + *
> > + * 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_NS_GPL(iio_backend_chan_disable, IIO_BACKEND);
> > +
> > +/**
> > + * iio_backend_chan_enable - Enable the backend.
> > + * @back:	Backend device
> 
> 
> 
> ...
> 
> 
> > +/**
> > + * devm_iio_backend_get_from_fwnode_lookup
> 
> Not valid kernel doc + name is wrong.  Make sure you run
> the kernel-doc script over this and fix any errors or warnings
> reported.

Noted.

> 
> > + * @dev:	Device where to bind the backend lifetime.
> > + * @fwnode:	Firmware node of the backend device.
> > + *
> > + * Search the backend list for a device matching @fwnode.
> > + * This API should not be used and it's only present for preventing the
> > first
> > + * user of this framework to break it's DT ABI.
> > + *
> > + * RETURNS:
> > + * A backend pointer, negative error pointer otherwise.
> > + */
> > +struct iio_backend *
> > +__devm_iio_backend_get_from_fwnode_lookup(struct device *dev,
> > +					  struct fwnode_handle *fwnode)
> > +{
> > +	struct iio_backend *back;
> > +	int ret;
> > +
> > +	guard(mutex)(&iio_back_lock);
> > +	list_for_each_entry(back, &iio_back_list, entry) {
> > +		if (!device_match_fwnode(back->dev, fwnode))
> > +			continue;
> > +
> > +		ret = __devm_iio_backend_get(dev, back);
> > +		if (ret)
> > +			return ERR_PTR(ret);
> > +
> > +		return back;
> > +	}
> > +
> > +	return ERR_PTR(-EPROBE_DEFER);
> > +}
> > +EXPORT_SYMBOL_NS_GPL(__devm_iio_backend_get_from_fwnode_lookup,
> > IIO_BACKEND);
> > 
> 
> 
> > +/**
> > + * 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.
> 
> It's unusual to 'insist' on the private data.
> Whilst it's highly likely it will always be there from a core point of view
> we don't mind it being NULL.  This is different from the ops as we want
> to be able to call those without checking they are there.
> 

Hmm, you're right. The private is for the callers to care as we don't really
touch it.

- Nuno Sá
> 

[PATCH v5 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 | 283 ++++++++++++++++++++++++++++++-----------------
 2 files changed, 183 insertions(+), 102 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 3b73c509bd68..6793faacb4dc 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -291,7 +291,7 @@ 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..b09f1ca9ad38 100644
--- a/drivers/iio/adc/ad9467.c
+++ b/drivers/iio/adc/ad9467.c
@@ -17,13 +17,12 @@
 #include <linux/of.h>
 
 
+#include <linux/iio/backend.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 
 #include <linux/clk.h>
 
-#include <linux/iio/adc/adi-axi-adc.h>
-
 /*
  * ADI High-Speed ADC common spi interface registers
  * See Application-Note AN-877:
@@ -102,15 +101,20 @@
 #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 +155,10 @@ 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 +195,13 @@ 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 +232,43 @@ 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 +276,23 @@ 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 +300,14 @@ 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 +318,15 @@ 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 +336,19 @@ 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 +360,53 @@ 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 +419,17 @@ 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 +437,27 @@ 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;
 
-	return ad9467_outputmode_set(st->spi, st->output_mode);
+	for (c = 0; c < st->info->num_channels; c++) {
+		ret = iio_backend_data_format_set(st->back, c, &data);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
 }
 
 static int ad9467_reset(struct device *dev)
@@ -443,25 +475,64 @@ static int ad9467_reset(struct device *dev)
 	return 0;
 }
 
+static int ad9467_iio_backend_get(struct ad9467_state *st)
+{
+	struct device *dev = &st->spi->dev;
+	struct device_node *__back;
+
+	st->back = devm_iio_backend_get(&st->spi->dev, NULL);
+	/* If not found, don't error out as we might have legacy DT property */
+	if (IS_ERR(st->back) && PTR_ERR(st->back) != -ENOENT)
+		return PTR_ERR(st->back);
+	if (!IS_ERR(st->back))
+		return 0;
+	/*
+	 * if we don't get the backend using the normal API's, use the legacy
+	 * 'adi,adc-dev' property. So we get all nodes with that property, and
+	 * look for the one pointing at us. Then we directly lookup that fwnode
+	 * on the backend list of registered devices. This is done so we don't
+	 * make io-backends mandatory which would break DT ABI.
+	 */
+	for_each_node_with_property(__back, "adi,adc-dev") {
+		struct device_node *__me;
+
+		__me = of_parse_phandle(__back, "adi,adc-dev", 0);
+		if (!__me)
+			continue;
+
+		if (!device_match_of_node(dev, __me)) {
+			of_node_put(__me);
+			continue;
+		}
+
+		of_node_put(__me);
+		st->back = __devm_iio_backend_get_from_fwnode_lookup(dev,
+								     of_fwnode_handle(__back));
+		of_node_put(__back);
+		return PTR_ERR_OR_ZERO(st->back);
+	}
+
+	return -ENODEV;
+}
+
 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 +546,39 @@ 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;
+	ret = ad9467_iio_backend_get(st);
+	if (ret)
+		return ret;
 
-	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[] = {
@@ -529,4 +610,4 @@ module_spi_driver(ad9467_driver);
 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
 MODULE_DESCRIPTION("Analog Devices AD9467 ADC driver");
 MODULE_LICENSE("GPL v2");
-MODULE_IMPORT_NS(IIO_ADI_AXI);
+MODULE_IMPORT_NS(IIO_BACKEND);

-- 
2.43.0

Re: [PATCH v5 7/8] iio: adc: ad9467: convert to backend framework

[Jonathan Cameron]

On Fri, 12 Jan 2024 17:40:21 +0100
Nuno Sa via B4 Relay <devnull+nuno.sa.analog.com@kernel.org> wrote:

> 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>

Hi Nuno,

Some trivial stuff in here (not I reviewed in reverse so might make more
sense read that way).  Mostly little changes that will reduce what
appears to be going on in this patch to the minimum possible


>  
> -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;

Keep an info variable around in here as well.

> -	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 +276,23 @@ 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);

Definitely good to keep local info variable here.

>  	unsigned int scale_val[2];
>  	unsigned int i;
>  	int ret;
> @@ -308,14 +300,14 @@ 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;
>  

>  }
>  
> -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);
Even here I'd keep a local info variable as it's harmless and
reduces what is changed in this patch.

>  	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 +360,53 @@ 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);
As below, I'd keep the local info variable to reduce scope of changes
to the minimum.

>  
>  	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_outputmode_set(struct spi_device *spi, unsigned int mode)
>  {
>  	int ret;
> @@ -401,19 +419,17 @@ 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;
	const struct adi_axi_adc_chip_info *info = st->info;
I think...

Makes this patch more minimal which is nice and it's not a bad change
in it's own right..

Same with some other cases changed by this patch.

>  
> -	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 +437,27 @@ 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;

Bit of a long line. Perhaps break it after the |

> +	ret = ad9467_outputmode_set(st->spi, mode);
> +	if (ret)
> +		return ret;
>  
> -	return ad9467_outputmode_set(st->spi, st->output_mode);
> +	for (c = 0; c < st->info->num_channels; c++) {
> +		ret = iio_backend_data_format_set(st->back, c, &data);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
>  }
>  
>  static int ad9467_reset(struct device *dev)
> @@ -443,25 +475,64 @@ static int ad9467_reset(struct device *dev)
>  	return 0;
>  }
>  
> +static int ad9467_iio_backend_get(struct ad9467_state *st)
> +{
> +	struct device *dev = &st->spi->dev;
> +	struct device_node *__back;
> +
> +	st->back = devm_iio_backend_get(&st->spi->dev, NULL);
> +	/* If not found, don't error out as we might have legacy DT property */
> +	if (IS_ERR(st->back) && PTR_ERR(st->back) != -ENOENT)
> +		return PTR_ERR(st->back);
> +	if (!IS_ERR(st->back))
> +		return 0;
Why not do this one first? I know I normally moan about having error handlers
out of line, but in this case the good is out of line whatever.

	if (!IS_ERR(st->back)
		return 0;

	if (PTR_ERR(st->back) != ENOENT)
		return PTR_ERR(st->back);

	...


> +	/*
> +	 * if we don't get the backend using the normal API's, use the legacy
> +	 * 'adi,adc-dev' property. So we get all nodes with that property, and
> +	 * look for the one pointing at us. Then we directly lookup that fwnode
> +	 * on the backend list of registered devices. This is done so we don't
> +	 * make io-backends mandatory which would break DT ABI.
> +	 */
> +	for_each_node_with_property(__back, "adi,adc-dev") {
> +		struct device_node *__me;
> +
> +		__me = of_parse_phandle(__back, "adi,adc-dev", 0);
> +		if (!__me)
> +			continue;
> +
> +		if (!device_match_of_node(dev, __me)) {
> +			of_node_put(__me);
> +			continue;
> +		}
> +
> +		of_node_put(__me);
> +		st->back = __devm_iio_backend_get_from_fwnode_lookup(dev,
> +								     of_fwnode_handle(__back));
> +		of_node_put(__back);
> +		return PTR_ERR_OR_ZERO(st->back);
> +	}
> +
> +	return -ENODEV;
> +}
> +
>  static int ad9467_probe(struct spi_device *spi)
>  {
>

>  
> -	st->output_mode = info->default_output_mode |
> -			  AN877_ADC_OUTPUT_MODE_TWOS_COMPLEMENT;
> +	ret = ad9467_iio_backend_get(st);
> +	if (ret)
> +		return ret;
>  
> -	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;

I'm curious there is no iio_backend_disable() to be done in the exit path?

> +
> +	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[] = {
> @@ -529,4 +610,4 @@ module_spi_driver(ad9467_driver);
>  MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
>  MODULE_DESCRIPTION("Analog Devices AD9467 ADC driver");
>  MODULE_LICENSE("GPL v2");
> -MODULE_IMPORT_NS(IIO_ADI_AXI);
> +MODULE_IMPORT_NS(IIO_BACKEND);
> 

Re: [PATCH v5 7/8] iio: adc: ad9467: convert to backend framework

[Nuno Sá]

On Fri, 2024-01-12 at 17:33 +0000, Jonathan Cameron wrote:
> On Fri, 12 Jan 2024 17:40:21 +0100
> Nuno Sa via B4 Relay <devnull+nuno.sa.analog.com@kernel.org> wrote:
> 
> > 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>
> 
> Hi Nuno,
> 
> Some trivial stuff in here (not I reviewed in reverse so might make more
> sense read that way).  Mostly little changes that will reduce what
> appears to be going on in this patch to the minimum possible
> 
> 
> > +
> >  static int ad9467_outputmode_set(struct spi_device *spi, unsigned int mode)
> >  {
> >  	int ret;
> > @@ -401,19 +419,17 @@ 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;
> 	const struct adi_axi_adc_chip_info *info = st->info;
> I think...
> 
> Makes this patch more minimal which is nice and it's not a bad change
> in it's own right..
> 
> Same with some other cases changed by this patch.

Alright, will do it in all the places you pointed out...

> 
> >  
> > -	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 +437,27 @@ 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;
> 
> Bit of a long line. Perhaps break it after the |

One of those cases where I think going beyond the 80 limit col helps
readability. But I can break the line if that's your preference.
 
> 
> > +	ret = ad9467_outputmode_set(st->spi, mode);
> > +	if (ret)
> > +		return ret;
> >  
> > -	return ad9467_outputmode_set(st->spi, st->output_mode);
> > +	for (c = 0; c < st->info->num_channels; c++) {
> > +		ret = iio_backend_data_format_set(st->back, c, &data);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	return 0;
> >  }
> >  
> >  static int ad9467_reset(struct device *dev)
> > @@ -443,25 +475,64 @@ static int ad9467_reset(struct device *dev)
> >  	return 0;
> >  }
> >  
> > +static int ad9467_iio_backend_get(struct ad9467_state *st)
> > +{
> > +	struct device *dev = &st->spi->dev;
> > +	struct device_node *__back;
> > +
> > +	st->back = devm_iio_backend_get(&st->spi->dev, NULL);
> > +	/* If not found, don't error out as we might have legacy DT
> > property */
> > +	if (IS_ERR(st->back) && PTR_ERR(st->back) != -ENOENT)
> > +		return PTR_ERR(st->back);
> > +	if (!IS_ERR(st->back))
> > +		return 0;
> Why not do this one first? I know I normally moan about having error handlers
> out of line, but in this case the good is out of line whatever.
> 
> 	if (!IS_ERR(st->back)
> 		return 0;
> 
> 	if (PTR_ERR(st->back) != ENOENT)
> 		return PTR_ERR(st->back);
> 
> 	...

Yeah, really because I wanted to have the error condition checked first. But I
agree in this particular case it makes the code simpler by not doing it that
way.

> 
> 
> > +	/*
> > +	 * if we don't get the backend using the normal API's, use the
> > legacy
> > +	 * 'adi,adc-dev' property. So we get all nodes with that property,
> > and
> > +	 * look for the one pointing at us. Then we directly lookup that
> > fwnode
> > +	 * on the backend list of registered devices. This is done so we
> > don't
> > +	 * make io-backends mandatory which would break DT ABI.
> > +	 */
> > +	for_each_node_with_property(__back, "adi,adc-dev") {
> > +		struct device_node *__me;
> > +
> > +		__me = of_parse_phandle(__back, "adi,adc-dev", 0);
> > +		if (!__me)
> > +			continue;
> > +
> > +		if (!device_match_of_node(dev, __me)) {
> > +			of_node_put(__me);
> > +			continue;
> > +		}
> > +
> > +		of_node_put(__me);
> > +		st->back = __devm_iio_backend_get_from_fwnode_lookup(dev,
> > +								    
> > of_fwnode_handle(__back));
> > +		of_node_put(__back);
> > +		return PTR_ERR_OR_ZERO(st->back);
> > +	}
> > +
> > +	return -ENODEV;
> > +}
> > +
> >  static int ad9467_probe(struct spi_device *spi)
> >  {
> > 
> 
> >  
> > -	st->output_mode = info->default_output_mode |
> > -			  AN877_ADC_OUTPUT_MODE_TWOS_COMPLEMENT;
> > +	ret = ad9467_iio_backend_get(st);
> > +	if (ret)
> > +		return ret;
> >  
> > -	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;
> 
> I'm curious there is no iio_backend_disable() to be done in the exit path?
> 

Ehehe something I have in my mind, yes. I'm just not disabling the core because
it was the same with the previous approach. My goal was to have (more or less)
the same state before vs after introducing the backend. I was thinking in adding
a devm_iio_backend_enable() as a follow up patch and use it in here (or actually
use it for the first axi-dac/dds user as that one will be come from a "clean"
state).

If you prefer I can already turn iio_backend_enable() ->
devm_iio_backend_enable() and use it in this patch.

- Nuno Sá
> 

Re: [PATCH v5 7/8] iio: adc: ad9467: convert to backend framework

[Jonathan Cameron]

> > > +		return ret;
> > > +
> > > +	ret = iio_backend_enable(st->back);
> > > +	if (ret)
> > > +		return ret;  
> > 
> > I'm curious there is no iio_backend_disable() to be done in the exit path?
> >   
> 
> Ehehe something I have in my mind, yes. I'm just not disabling the core because
> it was the same with the previous approach. My goal was to have (more or less)
> the same state before vs after introducing the backend. I was thinking in adding
> a devm_iio_backend_enable() as a follow up patch and use it in here (or actually
> use it for the first axi-dac/dds user as that one will be come from a "clean"
> state).
> 
> If you prefer I can already turn iio_backend_enable() ->
> devm_iio_backend_enable() and use it in this patch.
Might be cleaner to do that.  Or add a big fat comment here to say it'll get
cleaned up in a follow up patch.

> 
> - Nuno Sá
> >   

[PATCH v5 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             |   2 +-
 drivers/iio/adc/adi-axi-adc.c       | 380 +++++++++---------------------------
 include/linux/iio/adc/adi-axi-adc.h |  68 -------
 3 files changed, 93 insertions(+), 357 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 6793faacb4dc..02a55809cb6a 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -309,7 +309,7 @@ config ADI_AXI_ADC
 	select IIO_BUFFER_HW_CONSUMER
 	select IIO_BUFFER_DMAENGINE
 	select REGMAP_MMIO
-	depends on OF
+	select IIO_BACKEND
 	help
 	  Say yes here to build support for Analog Devices Generic
 	  AXI ADC IP core. The IP core is used for interfacing with
diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
index 0f21d1d98b9f..741b53c25bb1 100644
--- a/drivers/iio/adc/adi-axi-adc.c
+++ b/drivers/iio/adc/adi-axi-adc.c
@@ -8,6 +8,7 @@
 
 #include <linux/bitfield.h>
 #include <linux/clk.h>
+#include <linux/err.h>
 #include <linux/io.h>
 #include <linux/delay.h>
 #include <linux/module.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 },
@@ -448,3 +251,4 @@ MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
 MODULE_DESCRIPTION("Analog Devices Generic AXI ADC IP core driver");
 MODULE_LICENSE("GPL v2");
 MODULE_IMPORT_NS(IIO_DMAENGINE_BUFFER);
+MODULE_IMPORT_NS(IIO_BACKEND);
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 v5 8/8] iio: adc: adi-axi-adc: move to backend framework

[Jonathan Cameron]

On Fri, 12 Jan 2024 17:40:22 +0100
Nuno Sa via B4 Relay <devnull+nuno.sa.analog.com@kernel.org> wrote:

> 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>

A few quick drive by comments whist I wait for a build to finish...

> diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
> index 0f21d1d98b9f..741b53c25bb1 100644
> --- a/drivers/iio/adc/adi-axi-adc.c
> +++ b/drivers/iio/adc/adi-axi-adc.c
> @@ -8,6 +8,7 @@
>>  static int adi_axi_adc_probe(struct platform_device *pdev)
>  {
...

> @@ -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",

Format doesn't match with later.

> -			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",
I'd rip this (I think) unrelated change out to reduce noise in here somewhat.
I'm curious though as it's still %c above.


>  		 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;
>  }

Re: [PATCH v5 8/8] iio: adc: adi-axi-adc: move to backend framework

[Nuno Sá]

On Fri, 2024-01-12 at 17:39 +0000, Jonathan Cameron wrote:
> On Fri, 12 Jan 2024 17:40:22 +0100
> Nuno Sa via B4 Relay <devnull+nuno.sa.analog.com@kernel.org> wrote:
> 
> > 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>
> 
> A few quick drive by comments whist I wait for a build to finish...
> 
> > diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
> > index 0f21d1d98b9f..741b53c25bb1 100644
> > --- a/drivers/iio/adc/adi-axi-adc.c
> > +++ b/drivers/iio/adc/adi-axi-adc.c
> > @@ -8,6 +8,7 @@
> > >  static int adi_axi_adc_probe(struct platform_device *pdev)
> >  {
> ...
> 
> > @@ -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",
> 
> Format doesn't match with later.
> 
> > -			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",
> I'd rip this (I think) unrelated change out to reduce noise in here somewhat.
> I'm curious though as it's still %c above.

Oh, just forgot about the above %c... Yeah, the %c format gives a crappy output.
That's why I changed it :)

- Nuno Sá