[PATCH v2 0/4] Add support for AD7405/ADUM770x

[PATCH v2 0/4] Add support for AD7405/ADUM770x

[Pop Ioan Daniel]

The AD7405 is a high performance, second-order, Σ-Δ modulator
that converts an analog input signal into a high speed, single-bit
LVDS data stream, with on-chip digital isolation based on Analog
Devices, Inc., iCoupler technology. The AD7405 operates from a
4.5 V to 5.5 V (VDD1) power supply and accepts a differential input
signal of ±250 mV (±320 mV full-scale). The differential input is ideally
suited to shunt voltage monitoring in high voltage applications
where galvanic isolation is required.

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Content-Transfer-Encoding: 8bit

Pop Ioan Daniel (4):
  iio: backend: update iio_backend_oversampling_ratio_set
  iio: adc: adi-axi-adc: add set decimation rate
  dt-bindings: iio: adc: add ad7405
  iio: adc: ad7405: add ad7405 driver

 .../bindings/iio/adc/adi,ad7405.yaml          |  60 ++++
 drivers/iio/adc/Kconfig                       |  10 +
 drivers/iio/adc/Makefile                      |   1 +
 drivers/iio/adc/ad4851.c                      |   2 +-
 drivers/iio/adc/ad7405.c                      | 264 ++++++++++++++++++
 drivers/iio/adc/adi-axi-adc.c                 |  18 +-
 drivers/iio/industrialio-backend.c            |   3 +-
 include/linux/iio/backend.h                   |   3 +-
 8 files changed, 357 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad7405.yaml
 create mode 100644 drivers/iio/adc/ad7405.c

-- 
2.34.1

[PATCH v2 1/4] iio: backend: update iio_backend_oversampling_ratio_set

[Pop Ioan Daniel]

In the function iio_backend_oversampling_ratio_set the chan parameter
was added. The function can be used in contexts where the channel
must be specified. All affected files have been modified.

Signed-off-by: Pop Ioan Daniel <pop.ioan-daniel@analog.com>
---
changes in v2:
 - remove iio_backend_set_dec_rate function and use 
   iio_backend_oversampling_ratio_set function
 drivers/iio/adc/ad4851.c           | 2 +-
 drivers/iio/adc/adi-axi-adc.c      | 3 ++-
 drivers/iio/industrialio-backend.c | 3 ++-
 include/linux/iio/backend.h        | 3 ++-
 4 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/adc/ad4851.c b/drivers/iio/adc/ad4851.c
index 98ebc853db79..a943d5aac9e5 100644
--- a/drivers/iio/adc/ad4851.c
+++ b/drivers/iio/adc/ad4851.c
@@ -321,7 +321,7 @@ static int ad4851_set_oversampling_ratio(struct iio_dev *indio_dev,
 			return ret;
 	}
 
-	ret = iio_backend_oversampling_ratio_set(st->back, osr);
+	ret = iio_backend_oversampling_ratio_set(st->back, chan, osr);
 	if (ret)
 		return ret;
 
diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
index 4116c44197b8..9e8c30230791 100644
--- a/drivers/iio/adc/adi-axi-adc.c
+++ b/drivers/iio/adc/adi-axi-adc.c
@@ -381,7 +381,8 @@ static int axi_adc_ad485x_data_size_set(struct iio_backend *back,
 }
 
 static int axi_adc_ad485x_oversampling_ratio_set(struct iio_backend *back,
-					  unsigned int ratio)
+						 unsigned int chan,
+						 unsigned int ratio)
 {
 	struct adi_axi_adc_state *st = iio_backend_get_priv(back);
 
diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
index c1eb9ef9db08..a4e3e54fecb1 100644
--- a/drivers/iio/industrialio-backend.c
+++ b/drivers/iio/industrialio-backend.c
@@ -720,9 +720,10 @@ EXPORT_SYMBOL_NS_GPL(iio_backend_data_size_set, "IIO_BACKEND");
  * 0 on success, negative error number on failure.
  */
 int iio_backend_oversampling_ratio_set(struct iio_backend *back,
+				       unsigned int chan,
 				       unsigned int ratio)
 {
-	return iio_backend_op_call(back, oversampling_ratio_set, ratio);
+	return iio_backend_op_call(back, oversampling_ratio_set, chan, ratio);
 }
 EXPORT_SYMBOL_NS_GPL(iio_backend_oversampling_ratio_set, "IIO_BACKEND");
 
diff --git a/include/linux/iio/backend.h b/include/linux/iio/backend.h
index e59d909cb659..dbf4e4a5f4b1 100644
--- a/include/linux/iio/backend.h
+++ b/include/linux/iio/backend.h
@@ -144,7 +144,7 @@ struct iio_backend_ops {
 				  enum iio_backend_interface_type *type);
 	int (*data_size_set)(struct iio_backend *back, unsigned int size);
 	int (*oversampling_ratio_set)(struct iio_backend *back,
-				      unsigned int ratio);
+				      unsigned int chan, unsigned int ratio);
 	int (*read_raw)(struct iio_backend *back,
 			struct iio_chan_spec const *chan, int *val, int *val2,
 			long mask);
@@ -209,6 +209,7 @@ int iio_backend_interface_type_get(struct iio_backend *back,
 				   enum iio_backend_interface_type *type);
 int iio_backend_data_size_set(struct iio_backend *back, unsigned int size);
 int iio_backend_oversampling_ratio_set(struct iio_backend *back,
+				       unsigned int chan,
 				       unsigned int ratio);
 int iio_backend_read_raw(struct iio_backend *back,
 			 struct iio_chan_spec const *chan, int *val, int *val2,
-- 
2.34.1

Re: [PATCH v2 1/4] iio: backend: update iio_backend_oversampling_ratio_set

[David Lechner]

On 5/8/25 7:30 AM, Pop Ioan Daniel wrote:
> In the function iio_backend_oversampling_ratio_set the chan parameter
> was added. The function can be used in contexts where the channel
> must be specified. All affected files have been modified.
> 
> Signed-off-by: Pop Ioan Daniel <pop.ioan-daniel@analog.com>
> ---
> changes in v2:
>  - remove iio_backend_set_dec_rate function and use 
>    iio_backend_oversampling_ratio_set function
>  drivers/iio/adc/ad4851.c           | 2 +-
>  drivers/iio/adc/adi-axi-adc.c      | 3 ++-
>  drivers/iio/industrialio-backend.c | 3 ++-
>  include/linux/iio/backend.h        | 3 ++-
>  4 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad4851.c b/drivers/iio/adc/ad4851.c
> index 98ebc853db79..a943d5aac9e5 100644
> --- a/drivers/iio/adc/ad4851.c
> +++ b/drivers/iio/adc/ad4851.c
> @@ -321,7 +321,7 @@ static int ad4851_set_oversampling_ratio(struct iio_dev *indio_dev,
>  			return ret;
>  	}
>  
> -	ret = iio_backend_oversampling_ratio_set(st->back, osr);
> +	ret = iio_backend_oversampling_ratio_set(st->back, chan, osr);

Isn't this a compile error? chan here is const struct iio_chan_spec *, not
unsigned int.

>  	if (ret)
>  		return ret;
>  

Re: [PATCH v2 1/4] iio: backend: update iio_backend_oversampling_ratio_set

[kernel test robot]

Hi Pop,

kernel test robot noticed the following build errors:

[auto build test ERROR on jic23-iio/togreg]
[also build test ERROR on linus/master v6.15-rc5 next-20250508]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Pop-Ioan-Daniel/iio-backend-update-iio_backend_oversampling_ratio_set/20250508-203339
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git togreg
patch link:    https://lore.kernel.org/r/20250508123107.3797042-2-pop.ioan-daniel%40analog.com
patch subject: [PATCH v2 1/4] iio: backend: update iio_backend_oversampling_ratio_set
config: arm-randconfig-004-20250509 (https://download.01.org/0day-ci/archive/20250509/202505091706.owR2rZED-lkp@intel.com/config)
compiler: clang version 21.0.0git (https://github.com/llvm/llvm-project f819f46284f2a79790038e1f6649172789734ae8)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250509/202505091706.owR2rZED-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505091706.owR2rZED-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/iio/adc/ad4851.c:324:53: error: incompatible pointer to integer conversion passing 'const struct iio_chan_spec *' to parameter of type 'unsigned int' [-Wint-conversion]
     324 |         ret = iio_backend_oversampling_ratio_set(st->back, chan, osr);
         |                                                            ^~~~
   include/linux/iio/backend.h:212:25: note: passing argument to parameter 'chan' here
     212 |                                        unsigned int chan,
         |                                                     ^
   1 error generated.


vim +324 drivers/iio/adc/ad4851.c

   295	
   296	static int ad4851_set_oversampling_ratio(struct iio_dev *indio_dev,
   297						 const struct iio_chan_spec *chan,
   298						 unsigned int osr)
   299	{
   300		struct ad4851_state *st = iio_priv(indio_dev);
   301		int val, ret;
   302	
   303		guard(mutex)(&st->lock);
   304	
   305		if (osr == 1) {
   306			ret = regmap_clear_bits(st->regmap, AD4851_REG_OVERSAMPLE,
   307						AD4851_OS_EN_MSK);
   308			if (ret)
   309				return ret;
   310		} else {
   311			val = ad4851_osr_to_regval(osr);
   312			if (val < 0)
   313				return -EINVAL;
   314	
   315			ret = regmap_update_bits(st->regmap, AD4851_REG_OVERSAMPLE,
   316						 AD4851_OS_EN_MSK |
   317						 AD4851_OS_RATIO_MSK,
   318						 FIELD_PREP(AD4851_OS_EN_MSK, 1) |
   319						 FIELD_PREP(AD4851_OS_RATIO_MSK, val));
   320			if (ret)
   321				return ret;
   322		}
   323	
 > 324		ret = iio_backend_oversampling_ratio_set(st->back, chan, osr);
   325		if (ret)
   326			return ret;
   327	
   328		switch (st->info->resolution) {
   329		case 20:
   330			switch (osr) {
   331			case 0:
   332				return -EINVAL;
   333			case 1:
   334				val = 20;
   335				break;
   336			default:
   337				val = 24;
   338				break;
   339			}
   340			break;
   341		case 16:
   342			val = 16;
   343			break;
   344		default:
   345			return -EINVAL;
   346		}
   347	
   348		ret = iio_backend_data_size_set(st->back, val);
   349		if (ret)
   350			return ret;
   351	
   352		if (osr == 1 || st->info->resolution == 16) {
   353			ret = regmap_clear_bits(st->regmap, AD4851_REG_PACKET,
   354						AD4851_PACKET_FORMAT_MASK);
   355			if (ret)
   356				return ret;
   357	
   358			st->resolution_boost_enabled = false;
   359		} else {
   360			ret = regmap_update_bits(st->regmap, AD4851_REG_PACKET,
   361						 AD4851_PACKET_FORMAT_MASK,
   362						 FIELD_PREP(AD4851_PACKET_FORMAT_MASK, 1));
   363			if (ret)
   364				return ret;
   365	
   366			st->resolution_boost_enabled = true;
   367		}
   368	
   369		if (st->osr != osr) {
   370			ret = ad4851_scale_fill(indio_dev);
   371			if (ret)
   372				return ret;
   373	
   374			st->osr = osr;
   375		}
   376	
   377		return 0;
   378	}
   379	

-- 
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Re: [PATCH v2 1/4] iio: backend: update iio_backend_oversampling_ratio_set

[kernel test robot]

Hi Pop,

kernel test robot noticed the following build warnings:

[auto build test WARNING on jic23-iio/togreg]
[also build test WARNING on linus/master v6.15-rc5 next-20250508]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Pop-Ioan-Daniel/iio-backend-update-iio_backend_oversampling_ratio_set/20250508-203339
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git togreg
patch link:    https://lore.kernel.org/r/20250508123107.3797042-2-pop.ioan-daniel%40analog.com
patch subject: [PATCH v2 1/4] iio: backend: update iio_backend_oversampling_ratio_set
config: nios2-randconfig-001-20250509 (https://download.01.org/0day-ci/archive/20250509/202505091838.a9sKlbJN-lkp@intel.com/config)
compiler: nios2-linux-gcc (GCC) 13.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250509/202505091838.a9sKlbJN-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505091838.a9sKlbJN-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/iio/adc/ad4851.c: In function 'ad4851_set_oversampling_ratio':
>> drivers/iio/adc/ad4851.c:324:60: warning: passing argument 2 of 'iio_backend_oversampling_ratio_set' makes integer from pointer without a cast [-Wint-conversion]
     324 |         ret = iio_backend_oversampling_ratio_set(st->back, chan, osr);
         |                                                            ^~~~
         |                                                            |
         |                                                            const struct iio_chan_spec *
   In file included from drivers/iio/adc/ad4851.c:26:
   include/linux/iio/backend.h:212:53: note: expected 'unsigned int' but argument is of type 'const struct iio_chan_spec *'
     212 |                                        unsigned int chan,
         |                                        ~~~~~~~~~~~~~^~~~


vim +/iio_backend_oversampling_ratio_set +324 drivers/iio/adc/ad4851.c

   295	
   296	static int ad4851_set_oversampling_ratio(struct iio_dev *indio_dev,
   297						 const struct iio_chan_spec *chan,
   298						 unsigned int osr)
   299	{
   300		struct ad4851_state *st = iio_priv(indio_dev);
   301		int val, ret;
   302	
   303		guard(mutex)(&st->lock);
   304	
   305		if (osr == 1) {
   306			ret = regmap_clear_bits(st->regmap, AD4851_REG_OVERSAMPLE,
   307						AD4851_OS_EN_MSK);
   308			if (ret)
   309				return ret;
   310		} else {
   311			val = ad4851_osr_to_regval(osr);
   312			if (val < 0)
   313				return -EINVAL;
   314	
   315			ret = regmap_update_bits(st->regmap, AD4851_REG_OVERSAMPLE,
   316						 AD4851_OS_EN_MSK |
   317						 AD4851_OS_RATIO_MSK,
   318						 FIELD_PREP(AD4851_OS_EN_MSK, 1) |
   319						 FIELD_PREP(AD4851_OS_RATIO_MSK, val));
   320			if (ret)
   321				return ret;
   322		}
   323	
 > 324		ret = iio_backend_oversampling_ratio_set(st->back, chan, osr);
   325		if (ret)
   326			return ret;
   327	
   328		switch (st->info->resolution) {
   329		case 20:
   330			switch (osr) {
   331			case 0:
   332				return -EINVAL;
   333			case 1:
   334				val = 20;
   335				break;
   336			default:
   337				val = 24;
   338				break;
   339			}
   340			break;
   341		case 16:
   342			val = 16;
   343			break;
   344		default:
   345			return -EINVAL;
   346		}
   347	
   348		ret = iio_backend_data_size_set(st->back, val);
   349		if (ret)
   350			return ret;
   351	
   352		if (osr == 1 || st->info->resolution == 16) {
   353			ret = regmap_clear_bits(st->regmap, AD4851_REG_PACKET,
   354						AD4851_PACKET_FORMAT_MASK);
   355			if (ret)
   356				return ret;
   357	
   358			st->resolution_boost_enabled = false;
   359		} else {
   360			ret = regmap_update_bits(st->regmap, AD4851_REG_PACKET,
   361						 AD4851_PACKET_FORMAT_MASK,
   362						 FIELD_PREP(AD4851_PACKET_FORMAT_MASK, 1));
   363			if (ret)
   364				return ret;
   365	
   366			st->resolution_boost_enabled = true;
   367		}
   368	
   369		if (st->osr != osr) {
   370			ret = ad4851_scale_fill(indio_dev);
   371			if (ret)
   372				return ret;
   373	
   374			st->osr = osr;
   375		}
   376	
   377		return 0;
   378	}
   379	

-- 
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Re: [PATCH v2 1/4] iio: backend: update iio_backend_oversampling_ratio_set

[kernel test robot]

Hi Pop,

kernel test robot noticed the following build warnings:

[auto build test WARNING on jic23-iio/togreg]
[also build test WARNING on linus/master v6.15-rc5 next-20250509]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Pop-Ioan-Daniel/iio-backend-update-iio_backend_oversampling_ratio_set/20250508-203339
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git togreg
patch link:    https://lore.kernel.org/r/20250508123107.3797042-2-pop.ioan-daniel%40analog.com
patch subject: [PATCH v2 1/4] iio: backend: update iio_backend_oversampling_ratio_set
config: i386-randconfig-061-20250509 (https://download.01.org/0day-ci/archive/20250510/202505100131.FZe7C8ot-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250510/202505100131.FZe7C8ot-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505100131.FZe7C8ot-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> drivers/iio/adc/ad4851.c:324:60: sparse: sparse: incorrect type in argument 2 (different base types) @@     expected unsigned int chan @@     got struct iio_chan_spec const *chan @@
   drivers/iio/adc/ad4851.c:324:60: sparse:     expected unsigned int chan
   drivers/iio/adc/ad4851.c:324:60: sparse:     got struct iio_chan_spec const *chan

vim +324 drivers/iio/adc/ad4851.c

   295	
   296	static int ad4851_set_oversampling_ratio(struct iio_dev *indio_dev,
   297						 const struct iio_chan_spec *chan,
   298						 unsigned int osr)
   299	{
   300		struct ad4851_state *st = iio_priv(indio_dev);
   301		int val, ret;
   302	
   303		guard(mutex)(&st->lock);
   304	
   305		if (osr == 1) {
   306			ret = regmap_clear_bits(st->regmap, AD4851_REG_OVERSAMPLE,
   307						AD4851_OS_EN_MSK);
   308			if (ret)
   309				return ret;
   310		} else {
   311			val = ad4851_osr_to_regval(osr);
   312			if (val < 0)
   313				return -EINVAL;
   314	
   315			ret = regmap_update_bits(st->regmap, AD4851_REG_OVERSAMPLE,
   316						 AD4851_OS_EN_MSK |
   317						 AD4851_OS_RATIO_MSK,
   318						 FIELD_PREP(AD4851_OS_EN_MSK, 1) |
   319						 FIELD_PREP(AD4851_OS_RATIO_MSK, val));
   320			if (ret)
   321				return ret;
   322		}
   323	
 > 324		ret = iio_backend_oversampling_ratio_set(st->back, chan, osr);
   325		if (ret)
   326			return ret;
   327	
   328		switch (st->info->resolution) {
   329		case 20:
   330			switch (osr) {
   331			case 0:
   332				return -EINVAL;
   333			case 1:
   334				val = 20;
   335				break;
   336			default:
   337				val = 24;
   338				break;
   339			}
   340			break;
   341		case 16:
   342			val = 16;
   343			break;
   344		default:
   345			return -EINVAL;
   346		}
   347	
   348		ret = iio_backend_data_size_set(st->back, val);
   349		if (ret)
   350			return ret;
   351	
   352		if (osr == 1 || st->info->resolution == 16) {
   353			ret = regmap_clear_bits(st->regmap, AD4851_REG_PACKET,
   354						AD4851_PACKET_FORMAT_MASK);
   355			if (ret)
   356				return ret;
   357	
   358			st->resolution_boost_enabled = false;
   359		} else {
   360			ret = regmap_update_bits(st->regmap, AD4851_REG_PACKET,
   361						 AD4851_PACKET_FORMAT_MASK,
   362						 FIELD_PREP(AD4851_PACKET_FORMAT_MASK, 1));
   363			if (ret)
   364				return ret;
   365	
   366			st->resolution_boost_enabled = true;
   367		}
   368	
   369		if (st->osr != osr) {
   370			ret = ad4851_scale_fill(indio_dev);
   371			if (ret)
   372				return ret;
   373	
   374			st->osr = osr;
   375		}
   376	
   377		return 0;
   378	}
   379	

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[PATCH v2 2/4] iio: adc: adi-axi-adc: add set decimation rate

[Pop Ioan Daniel]

Add support for setting decimation rate.

Signed-off-by: Pop Ioan Daniel <pop.ioan-daniel@analog.com>
---
changes in v2:
 - update ADI_AXI_ADC_REG_CHAN_USR_CTRL_2 register in a per-channel register
 - rename ADI_AXI_ADC_DEC_RATE_MASK in
   ADI_AXI_ADC_CHAN_USR_CTRL_2_DEC_RATE_N_MASK
 - add channel index parameter to keep axi_adc_set_dec_rate generic
 - remove ad7405 chip-specific struct
 drivers/iio/adc/adi-axi-adc.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
index 9e8c30230791..33eb8f337e0b 100644
--- a/drivers/iio/adc/adi-axi-adc.c
+++ b/drivers/iio/adc/adi-axi-adc.c
@@ -80,6 +80,9 @@
 #define ADI_AXI_ADC_REG_CHAN_CTRL_3(c)		(0x0418 + (c) * 0x40)
 #define   ADI_AXI_ADC_CHAN_PN_SEL_MASK		GENMASK(19, 16)
 
+#define ADI_AXI_ADC_REG_CHAN_USR_CTRL_2(c)	(0x0424 + (c) * 0x40)
+#define   ADI_AXI_ADC_CHAN_USR_CTRL_2_DEC_RATE_N_MASK		GENMASK(15, 0)
+
 /* IO Delays */
 #define ADI_AXI_ADC_REG_DELAY(l)		(0x0800 + (l) * 0x4)
 #define   AXI_ADC_DELAY_CTRL_MASK		GENMASK(4, 0)
@@ -242,6 +245,17 @@ static int axi_adc_test_pattern_set(struct iio_backend *back,
 	}
 }
 
+static int axi_adc_set_dec_rate(struct iio_backend *back, unsigned int chan,
+				unsigned int rate)
+{
+	struct adi_axi_adc_state *st = iio_backend_get_priv(back);
+
+	return regmap_update_bits(st->regmap,
+				  ADI_AXI_ADC_REG_CHAN_USR_CTRL_2(chan),
+				  ADI_AXI_ADC_CHAN_USR_CTRL_2_DEC_RATE_N_MASK,
+				  FIELD_PREP(ADI_AXI_ADC_CHAN_USR_CTRL_2_DEC_RATE_N_MASK, rate));
+}
+
 static int axi_adc_read_chan_status(struct adi_axi_adc_state *st, unsigned int chan,
 				    unsigned int *status)
 {
@@ -550,6 +564,7 @@ static const struct iio_backend_ops adi_axi_adc_ops = {
 	.test_pattern_set = axi_adc_test_pattern_set,
 	.chan_status = axi_adc_chan_status,
 	.interface_type_get = axi_adc_interface_type_get,
+	.oversampling_ratio_set = axi_adc_set_dec_rate,
 	.debugfs_reg_access = iio_backend_debugfs_ptr(axi_adc_reg_access),
 	.debugfs_print_chan_status = iio_backend_debugfs_ptr(axi_adc_debugfs_print_chan_status),
 };
-- 
2.34.1

Re: [PATCH v2 2/4] iio: adc: adi-axi-adc: add set decimation rate

[David Lechner]

On 5/8/25 7:30 AM, Pop Ioan Daniel wrote:
> Add support for setting decimation rate.
> 
> Signed-off-by: Pop Ioan Daniel <pop.ioan-daniel@analog.com>
> ---
> changes in v2:
>  - update ADI_AXI_ADC_REG_CHAN_USR_CTRL_2 register in a per-channel register
>  - rename ADI_AXI_ADC_DEC_RATE_MASK in
>    ADI_AXI_ADC_CHAN_USR_CTRL_2_DEC_RATE_N_MASK
>  - add channel index parameter to keep axi_adc_set_dec_rate generic
>  - remove ad7405 chip-specific struct
>  drivers/iio/adc/adi-axi-adc.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
> index 9e8c30230791..33eb8f337e0b 100644
> --- a/drivers/iio/adc/adi-axi-adc.c
> +++ b/drivers/iio/adc/adi-axi-adc.c
> @@ -80,6 +80,9 @@
>  #define ADI_AXI_ADC_REG_CHAN_CTRL_3(c)		(0x0418 + (c) * 0x40)
>  #define   ADI_AXI_ADC_CHAN_PN_SEL_MASK		GENMASK(19, 16)
>  
> +#define ADI_AXI_ADC_REG_CHAN_USR_CTRL_2(c)	(0x0424 + (c) * 0x40)
> +#define   ADI_AXI_ADC_CHAN_USR_CTRL_2_DEC_RATE_N_MASK		GENMASK(15, 0)
> +
>  /* IO Delays */
>  #define ADI_AXI_ADC_REG_DELAY(l)		(0x0800 + (l) * 0x4)
>  #define   AXI_ADC_DELAY_CTRL_MASK		GENMASK(4, 0)
> @@ -242,6 +245,17 @@ static int axi_adc_test_pattern_set(struct iio_backend *back,
>  	}
>  }
>  
> +static int axi_adc_set_dec_rate(struct iio_backend *back, unsigned int chan,
> +				unsigned int rate)
> +{
> +	struct adi_axi_adc_state *st = iio_backend_get_priv(back);
> +
> +	return regmap_update_bits(st->regmap,
> +				  ADI_AXI_ADC_REG_CHAN_USR_CTRL_2(chan),
> +				  ADI_AXI_ADC_CHAN_USR_CTRL_2_DEC_RATE_N_MASK,
> +				  FIELD_PREP(ADI_AXI_ADC_CHAN_USR_CTRL_2_DEC_RATE_N_MASK, rate));

Rate is getting a bit far past 80 chars, so would be nice to wrap that line.

> +}
> +
>  static int axi_adc_read_chan_status(struct adi_axi_adc_state *st, unsigned int chan,
>  				    unsigned int *status)
>  {
> @@ -550,6 +564,7 @@ static const struct iio_backend_ops adi_axi_adc_ops = {
>  	.test_pattern_set = axi_adc_test_pattern_set,
>  	.chan_status = axi_adc_chan_status,
>  	.interface_type_get = axi_adc_interface_type_get,
> +	.oversampling_ratio_set = axi_adc_set_dec_rate,

Would make more sense if function was named axi_adc_oversampling_ratio_set.
(Making the names match exactly (with namespace prefix added) make less info
you have to hold in your head when reading the driver.)

>  	.debugfs_reg_access = iio_backend_debugfs_ptr(axi_adc_reg_access),
>  	.debugfs_print_chan_status = iio_backend_debugfs_ptr(axi_adc_debugfs_print_chan_status),
>  };

[PATCH v2 3/4] dt-bindings: iio: adc: add ad7405

[Pop Ioan Daniel]

Add devicetree bindings for ad7405/adum770x family.

Signed-off-by: Pop Ioan Daniel <pop.ioan-daniel@analog.com>
---
changes in v2:
 - remove  #address-cells and #size-cells
 - add additionalProperties: false instead of unevaluatedProperties: false
 - remove #include <dt-bindings/interrupt-controller/irq.h>
   because it's not used
 - add new line at the end of the file
 - add mantainer
 .../bindings/iio/adc/adi,ad7405.yaml          | 60 +++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad7405.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7405.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7405.yaml
new file mode 100644
index 000000000000..8c30a712968d
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7405.yaml
@@ -0,0 +1,60 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+# Copyright 2025 Analog Devices Inc.
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/adi,ad7405.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AD7405 family
+
+maintainers:
+  - Dragos Bogdan <dragos.bogdan@analog.com>
+  - Pop Ioan Daniel <pop.ioan-daniel@analog.com>
+
+description: |
+  Analog Devices AD7405 is a high performance isolated ADC, 1-channel,
+  16-bit with a second-order Σ-Δ modulator that converts an analog input signal
+  into a high speed, single-bit data stream.
+
+  https://www.analog.com/media/en/technical-documentation/data-sheets/ad7405.pdf
+  https://www.analog.com/media/en/technical-documentation/data-sheets/adum7701.pdf
+  https://www.analog.com/media/en/technical-documentation/data-sheets/adum7702.pdf
+  https://www.analog.com/media/en/technical-documentation/data-sheets/ADuM7703.pdf
+
+properties:
+  compatible:
+    enum:
+      - adi,ad7405
+      - adi,adum7701
+      - adi,adum7702
+      - adi,adum7703
+
+  vdd1-supply: true
+
+  vdd2-supply: true
+
+  clocks:
+    maxitems: 1
+
+  io-backends:
+    maxItems: 1
+
+required:
+  - compatible
+  - vdd1-supply
+  - vdd2-supply
+  - clocks
+  - io-backends
+
+additionalProperties: false
+
+examples:
+  - |
+    adc {
+        compatible = "adi,ad7405";
+        clocks = <&axi_clk_gen 0>;
+        vdd1-supply = <&vdd1>;
+        vdd2-supply = <&vdd2>;
+        io-backends = <&iio_backend>;
+    };
+...
-- 
2.34.1

Re: [PATCH v2 3/4] dt-bindings: iio: adc: add ad7405

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 2854 bytes --]

On Thu, May 08, 2025 at 03:30:56PM +0300, Pop Ioan Daniel wrote:
> Add devicetree bindings for ad7405/adum770x family.
> 
> Signed-off-by: Pop Ioan Daniel <pop.ioan-daniel@analog.com>
> ---
> changes in v2:
>  - remove  #address-cells and #size-cells
>  - add additionalProperties: false instead of unevaluatedProperties: false
>  - remove #include <dt-bindings/interrupt-controller/irq.h>
>    because it's not used
>  - add new line at the end of the file
>  - add mantainer
>  .../bindings/iio/adc/adi,ad7405.yaml          | 60 +++++++++++++++++++
>  1 file changed, 60 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad7405.yaml
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7405.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7405.yaml
> new file mode 100644
> index 000000000000..8c30a712968d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7405.yaml
> @@ -0,0 +1,60 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +# Copyright 2025 Analog Devices Inc.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/adc/adi,ad7405.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Analog Devices AD7405 family
> +
> +maintainers:
> +  - Dragos Bogdan <dragos.bogdan@analog.com>
> +  - Pop Ioan Daniel <pop.ioan-daniel@analog.com>
> +
> +description: |
> +  Analog Devices AD7405 is a high performance isolated ADC, 1-channel,
> +  16-bit with a second-order Σ-Δ modulator that converts an analog input signal
> +  into a high speed, single-bit data stream.
> +
> +  https://www.analog.com/media/en/technical-documentation/data-sheets/ad7405.pdf
> +  https://www.analog.com/media/en/technical-documentation/data-sheets/adum7701.pdf
> +  https://www.analog.com/media/en/technical-documentation/data-sheets/adum7702.pdf
> +  https://www.analog.com/media/en/technical-documentation/data-sheets/ADuM7703.pdf
> +
> +properties:
> +  compatible:
> +    enum:
> +      - adi,ad7405
> +      - adi,adum7701
> +      - adi,adum7702
> +      - adi,adum7703

These last three devices have the same match data, why is a fallback
compatible not appropriate? (Please list the reason in your commit
message).

> +
> +  vdd1-supply: true
> +
> +  vdd2-supply: true
> +
> +  clocks:
> +    maxitems: 1
> +
> +  io-backends:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - vdd1-supply
> +  - vdd2-supply
> +  - clocks
> +  - io-backends
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    adc {
> +        compatible = "adi,ad7405";
> +        clocks = <&axi_clk_gen 0>;
> +        vdd1-supply = <&vdd1>;
> +        vdd2-supply = <&vdd2>;
> +        io-backends = <&iio_backend>;
> +    };
> +...
> -- 
> 2.34.1
> 

[-- Attachment #2: signature.asc --]
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Re: [PATCH v2 3/4] dt-bindings: iio: adc: add ad7405

[Rob Herring (Arm)]

On Thu, 08 May 2025 15:30:56 +0300, Pop Ioan Daniel wrote:
> Add devicetree bindings for ad7405/adum770x family.
> 
> Signed-off-by: Pop Ioan Daniel <pop.ioan-daniel@analog.com>
> ---
> changes in v2:
>  - remove  #address-cells and #size-cells
>  - add additionalProperties: false instead of unevaluatedProperties: false
>  - remove #include <dt-bindings/interrupt-controller/irq.h>
>    because it's not used
>  - add new line at the end of the file
>  - add mantainer
>  .../bindings/iio/adc/adi,ad7405.yaml          | 60 +++++++++++++++++++
>  1 file changed, 60 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad7405.yaml
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/iio/adc/adi,ad7405.yaml: properties:clocks: 'anyOf' conditional failed, one must be fixed:
	'maxitems' is not one of ['$ref', 'additionalItems', 'additionalProperties', 'allOf', 'anyOf', 'const', 'contains', 'default', 'dependencies', 'dependentRequired', 'dependentSchemas', 'deprecated', 'description', 'else', 'enum', 'exclusiveMaximum', 'exclusiveMinimum', 'items', 'if', 'minItems', 'minimum', 'maxItems', 'maximum', 'multipleOf', 'not', 'oneOf', 'pattern', 'patternProperties', 'properties', 'required', 'then', 'typeSize', 'unevaluatedProperties', 'uniqueItems']
	'type' was expected
	from schema $id: http://devicetree.org/meta-schemas/keywords.yaml#
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/iio/adc/adi,ad7405.yaml: properties:clocks: 'anyOf' conditional failed, one must be fixed:
	'maxItems' is a required property
		hint: Only "maxItems" is required for a single entry if there are no constraints defined for the values.
	'maxitems' is not one of ['maxItems', 'description', 'deprecated']
		hint: Only "maxItems" is required for a single entry if there are no constraints defined for the values.
	Additional properties are not allowed ('maxitems' was unexpected)
		hint: Arrays must be described with a combination of minItems/maxItems/items
	'maxitems' is not one of ['description', 'deprecated', 'const', 'enum', 'minimum', 'maximum', 'multipleOf', 'default', '$ref', 'oneOf']
	hint: cell array properties must define how many entries and what the entries are when there is more than one entry.
	from schema $id: http://devicetree.org/meta-schemas/clocks.yaml#

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20250508123107.3797042-4-pop.ioan-daniel@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 v2 4/4] iio: adc: ad7405: add ad7405 driver

[Pop Ioan Daniel]

Add support for the AD7405/ADUM770x, a high performance isolated ADC,
1-channel, 16-bit with a second-order Σ-Δ modulator that converts an
analog input signal into a high speed, single-bit data stream.

Signed-off-by: Pop Ioan Daniel <pop.ioan-daniel@analog.com>
---
changes in v2:

 - sort the includes in alphabetical order
 - delete headers that aren't used
 - remove min_rate member
 - remove ad7405_update_scan_mode because there is only one channel
 - rename axi_clk_gen to clk
 - remove unuseful members from ad7405 state struct
 - return -EINVAL on ad7405_write_raw
 - fix indentation
 - remove blank lines
 - remove chan, bits, sign parameters from AD7405_IIO_CHANNEL
 - remove shift = 0
 - add info_mask_shared_by_type with IIO_CHAN_INFO_SCALE and
   IIO_CHAN_INFO_OFFSET flags
 - add scan_index, differential, channel2 in AD7405_IIO_CHANNEL
 - remove ad7405_channel_masks[]
 - remove unuseful members from ad7405_chip_info struct
 - remove platform_get_drvdata() from probe
 - use device_get_match_data to be able to use different chip info
 - use devm_clk_get_enabled() for efficiency
 - add devm_add_action_or_reset to disable_unprepare the clock when the driver
   is removed
 - replace the devm_regulator_bulk_get_enable before applying any other signals
 - check for return value of 0 for st->ref_frequency
 - remove indio_dev->modes = INDIO_DIRECT_MODE
 - remove iio_backend_disable/enable that is done implicitly
   by devm_iio_backend_enable()
 drivers/iio/adc/Kconfig  |  10 ++
 drivers/iio/adc/Makefile |   1 +
 drivers/iio/adc/ad7405.c | 264 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 275 insertions(+)
 create mode 100644 drivers/iio/adc/ad7405.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index ad06cf556785..6ed1042636d9 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -251,6 +251,16 @@ config AD7380
 	  To compile this driver as a module, choose M here: the module will be
 	  called ad7380.
 
+config AD7405
+	tristate "Analog Device AD7405 ADC Driver"
+	select IIO_BACKEND
+	help
+	  Say yes here to build support for Analog Devices AD7405, ADUM7701,
+	  ADUM7702, ADUM7703 analog to digital converters (ADC).
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called ad7405.
+
 config AD7476
 	tristate "Analog Devices AD7476 1-channel ADCs driver and other similar devices from AD and TI"
 	depends on SPI
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 07d4b832c42e..8115f30b7862 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_AD7291) += ad7291.o
 obj-$(CONFIG_AD7292) += ad7292.o
 obj-$(CONFIG_AD7298) += ad7298.o
 obj-$(CONFIG_AD7380) += ad7380.o
+obj-$(CONFIG_AD7405) += ad7405.o
 obj-$(CONFIG_AD7476) += ad7476.o
 obj-$(CONFIG_AD7606_IFACE_PARALLEL) += ad7606_par.o
 obj-$(CONFIG_AD7606_IFACE_SPI) += ad7606_spi.o
diff --git a/drivers/iio/adc/ad7405.c b/drivers/iio/adc/ad7405.c
new file mode 100644
index 000000000000..5fe36ce61819
--- /dev/null
+++ b/drivers/iio/adc/ad7405.c
@@ -0,0 +1,264 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Analog Devices AD7405 driver
+ *
+ * Copyright 2025 Analog Devices Inc.
+ */
+
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regulator/consumer.h>
+#include <linux/util_macros.h>
+
+#include <linux/iio/backend.h>
+#include <linux/iio/iio.h>
+
+const unsigned int ad7405_dec_rates[] = {
+	4096, 2048, 1024, 512, 256, 128, 64, 32,
+};
+
+struct ad7405_chip_info {
+	const char *name;
+	unsigned int max_rate;
+	struct iio_chan_spec channel[];
+};
+
+struct ad7405_state {
+	struct iio_backend *back;
+	/* lock to protect multiple accesses to the device registers */
+	struct mutex lock;
+	const struct ad7405_chip_info *info;
+	unsigned int sample_frequency_tbl[ARRAY_SIZE(ad7405_dec_rates)];
+	unsigned int sample_frequency;
+	unsigned int ref_frequency;
+};
+
+static void ad7405_fill_samp_freq_table(struct ad7405_state *st)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(ad7405_dec_rates); i++)
+		st->sample_frequency_tbl[i] =
+			DIV_ROUND_CLOSEST_ULL(st->ref_frequency, ad7405_dec_rates[i]);
+}
+
+static int ad7405_set_sampling_rate(struct iio_dev *indio_dev,
+				    const struct iio_chan_spec *chan,
+				    unsigned int samp_rate)
+{
+	struct ad7405_state *st = iio_priv(indio_dev);
+	unsigned int dec_rate, idx;
+	int ret;
+
+	dec_rate = DIV_ROUND_CLOSEST_ULL(st->ref_frequency, samp_rate);
+
+	idx = find_closest_descending(dec_rate, ad7405_dec_rates,
+				      ARRAY_SIZE(ad7405_dec_rates));
+
+	dec_rate = ad7405_dec_rates[idx];
+
+	ret = iio_backend_oversampling_ratio_set(st->back, 0, dec_rate);
+	if (ret)
+		return ret;
+
+	st->sample_frequency = DIV_ROUND_CLOSEST_ULL(st->ref_frequency, dec_rate);
+
+	return 0;
+}
+
+static int ad7405_read_raw(struct iio_dev *indio_dev,
+			   const struct iio_chan_spec *chan, int *val,
+			   int *val2, long info)
+{
+	struct ad7405_state *st = iio_priv(indio_dev);
+
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = st->sample_frequency;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad7405_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int val,
+			    int val2, long info)
+{
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		if (val < 1)
+			return -EINVAL;
+		return ad7405_set_sampling_rate(indio_dev, chan, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad7405_read_avail(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     const int **vals, int *type, int *length,
+			     long info)
+{
+	struct ad7405_state *st = iio_priv(indio_dev);
+
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+			*vals = st->sample_frequency_tbl;
+			*length = ARRAY_SIZE(st->sample_frequency_tbl);
+			*type = IIO_VAL_INT;
+			return IIO_AVAIL_LIST;
+	default:
+			return -EINVAL;
+	}
+}
+
+static void ad7405_clk_disable_unprepare(void *clk)
+{
+	clk_disable_unprepare(clk);
+}
+
+static const struct iio_info ad7405_iio_info = {
+	.read_raw = &ad7405_read_raw,
+	.write_raw = &ad7405_write_raw,
+	.read_avail = &ad7405_read_avail,
+};
+
+#define AD7405_IIO_CHANNEL {							\
+	.type = IIO_VOLTAGE,							\
+	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),		\
+	.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |			\
+		BIT(IIO_CHAN_INFO_OFFSET),					\
+	.indexed = 1,								\
+	.channel = 0,								\
+	.channel2 = 1,								\
+	.differential = 1,							\
+	.scan_index = 0,							\
+	.scan_type = {								\
+		.sign = 'u',							\
+		.realbits = 16,							\
+		.storagebits = 16,						\
+	},									\
+}
+
+static const struct ad7405_chip_info ad7405_chip_info = {
+		.name = "AD7405",
+		.channel = {
+			AD7405_IIO_CHANNEL,
+		},
+};
+
+static const struct ad7405_chip_info adum7701_chip_info = {
+		.name = "ADUM7701",
+		.channel = {
+			AD7405_IIO_CHANNEL,
+		},
+};
+
+static const char * const ad7405_power_supplies[] = {
+	"vdd1",	"vdd2",
+};
+
+static int ad7405_probe(struct platform_device *pdev)
+{
+	const struct ad7405_chip_info *chip_info;
+	struct device *dev = &pdev->dev;
+	struct iio_dev *indio_dev;
+	struct ad7405_state *st;
+	struct clk *clk;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+
+	ret = devm_mutex_init(dev, &st->lock);
+	if (ret)
+		return ret;
+
+	chip_info = device_get_match_data(dev);
+	if (!chip_info)
+		return dev_err_probe(dev, -EINVAL, "no chip info\n");
+
+	ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(ad7405_power_supplies),
+					     ad7405_power_supplies);
+
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to get and enable supplies");
+
+	clk = devm_clk_get_enabled(dev, NULL);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	ret = devm_add_action_or_reset(dev, ad7405_clk_disable_unprepare, clk);
+	if (ret)
+		return ret;
+
+	st->ref_frequency = clk_get_rate(clk);
+	if (!(st->ref_frequency))
+		return -EINVAL;
+
+	ad7405_fill_samp_freq_table(st);
+
+	indio_dev->dev.parent = dev;
+	indio_dev->name = chip_info->name;
+	indio_dev->channels = chip_info->channel;
+	indio_dev->num_channels = 1;
+	indio_dev->info = &ad7405_iio_info;
+
+	st->back = devm_iio_backend_get(dev, NULL);
+	if (IS_ERR(st->back))
+		return dev_err_probe(dev, PTR_ERR(st->back),
+				     "failed to get IIO backend");
+
+	ret = iio_backend_chan_enable(st->back, 0);
+	if (ret)
+		return ret;
+
+	ret = devm_iio_backend_request_buffer(dev, st->back, indio_dev);
+	if (ret)
+		return ret;
+
+	ret = devm_iio_backend_enable(dev, st->back);
+	if (ret)
+		return ret;
+
+	ret = ad7405_set_sampling_rate(indio_dev, &indio_dev->channels[0],
+				       chip_info->max_rate);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+/* Match table for of_platform binding */
+static const struct of_device_id ad7405_of_match[] = {
+	{ .compatible = "adi,ad7405", .data = &ad7405_chip_info, },
+	{ .compatible = "adi,adum7701", .data = &adum7701_chip_info, },
+	{ .compatible = "adi,adum7702", .data = &adum7701_chip_info, },
+	{ .compatible = "adi,adum7703", .data = &adum7701_chip_info, },
+	{ /* end of list */ },
+};
+MODULE_DEVICE_TABLE(of, ad7405_of_match);
+
+static struct platform_driver ad7405_driver = {
+	.driver = {
+		.name = "ad7405",
+		.owner = THIS_MODULE,
+		.of_match_table = ad7405_of_match,
+	},
+	.probe = ad7405_probe,
+};
+module_platform_driver(ad7405_driver);
+
+MODULE_AUTHOR("Dragos Bogdan <dragos.bogdan@analog.com>");
+MODULE_AUTHOR("Pop Ioan Daniel <pop.ioan-daniel@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD7405 driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_BACKEND");
-- 
2.34.1

Re: [PATCH v2 4/4] iio: adc: ad7405: add ad7405 driver

[David Lechner]

On 5/8/25 7:30 AM, Pop Ioan Daniel wrote:
> Add support for the AD7405/ADUM770x, a high performance isolated ADC,
> 1-channel, 16-bit with a second-order Σ-Δ modulator that converts an
> analog input signal into a high speed, single-bit data stream.
> 
> Signed-off-by: Pop Ioan Daniel <pop.ioan-daniel@analog.com>
> ---

...

> diff --git a/drivers/iio/adc/ad7405.c b/drivers/iio/adc/ad7405.c
> new file mode 100644
> index 000000000000..5fe36ce61819
> --- /dev/null
> +++ b/drivers/iio/adc/ad7405.c
> @@ -0,0 +1,264 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Analog Devices AD7405 driver
> + *
> + * Copyright 2025 Analog Devices Inc.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/module.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/util_macros.h>
> +
> +#include <linux/iio/backend.h>
> +#include <linux/iio/iio.h>
> +
> +const unsigned int ad7405_dec_rates[] = {
> +	4096, 2048, 1024, 512, 256, 128, 64, 32,
> +};
> +
> +struct ad7405_chip_info {
> +	const char *name;
> +	unsigned int max_rate;
> +	struct iio_chan_spec channel[];

Since there is only one channel, we can drop the [] here.

> +};
> +
> +struct ad7405_state {
> +	struct iio_backend *back;
> +	/* lock to protect multiple accesses to the device registers */
> +	struct mutex lock;

This lock isn't used and can be removed.

> +	const struct ad7405_chip_info *info;
> +	unsigned int sample_frequency_tbl[ARRAY_SIZE(ad7405_dec_rates)];
> +	unsigned int sample_frequency;
> +	unsigned int ref_frequency;
> +};
> +
> +static void ad7405_fill_samp_freq_table(struct ad7405_state *st)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(ad7405_dec_rates); i++)
> +		st->sample_frequency_tbl[i] =
> +			DIV_ROUND_CLOSEST_ULL(st->ref_frequency, ad7405_dec_rates[i]);
> +}
> +
> +static int ad7405_set_sampling_rate(struct iio_dev *indio_dev,
> +				    const struct iio_chan_spec *chan,
> +				    unsigned int samp_rate)
> +{
> +	struct ad7405_state *st = iio_priv(indio_dev);
> +	unsigned int dec_rate, idx;
> +	int ret;
> +
> +	dec_rate = DIV_ROUND_CLOSEST_ULL(st->ref_frequency, samp_rate);
> +
> +	idx = find_closest_descending(dec_rate, ad7405_dec_rates,
> +				      ARRAY_SIZE(ad7405_dec_rates));
> +
> +	dec_rate = ad7405_dec_rates[idx];
> +
> +	ret = iio_backend_oversampling_ratio_set(st->back, 0, dec_rate);
> +	if (ret)
> +		return ret;
> +
> +	st->sample_frequency = DIV_ROUND_CLOSEST_ULL(st->ref_frequency, dec_rate);
> +
> +	return 0;
> +}
> +
> +static int ad7405_read_raw(struct iio_dev *indio_dev,
> +			   const struct iio_chan_spec *chan, int *val,
> +			   int *val2, long info)
> +{
> +	struct ad7405_state *st = iio_priv(indio_dev);
> +
> +	switch (info) {

This is missing an implementation for IIO_CHAN_INFO_SCALE and IIO_CHAN_INFO_OFFSET.

> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		*val = st->sample_frequency;
> +		return IIO_VAL_INT;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ad7405_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan, int val,
> +			    int val2, long info)
> +{
> +	switch (info) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		if (val < 1)
> +			return -EINVAL;
> +		return ad7405_set_sampling_rate(indio_dev, chan, val);
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ad7405_read_avail(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     const int **vals, int *type, int *length,
> +			     long info)
> +{
> +	struct ad7405_state *st = iio_priv(indio_dev);
> +
> +	switch (info) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +			*vals = st->sample_frequency_tbl;
> +			*length = ARRAY_SIZE(st->sample_frequency_tbl);
> +			*type = IIO_VAL_INT;
> +			return IIO_AVAIL_LIST;
> +	default:
> +			return -EINVAL;
> +	}
> +}
> +
> +static void ad7405_clk_disable_unprepare(void *clk)
> +{
> +	clk_disable_unprepare(clk);
> +}
> +
> +static const struct iio_info ad7405_iio_info = {
> +	.read_raw = &ad7405_read_raw,
> +	.write_raw = &ad7405_write_raw,
> +	.read_avail = &ad7405_read_avail,
> +};
> +
> +#define AD7405_IIO_CHANNEL {							\
> +	.type = IIO_VOLTAGE,							\
> +	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),		\
> +	.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),	\

Would it make more sense to use IIO_CHAN_INFO_OVERSAMPLING_RATIO for controlling
the decimation rate and have IIO_CHAN_INFO_SAMP_FREQ be read-only?

Maybe also useful to have a read-only filter_type attribute to say that the
backend is providing a sinc3 filter?

> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |			\
> +		BIT(IIO_CHAN_INFO_OFFSET),					\
> +	.indexed = 1,								\
> +	.channel = 0,								\
> +	.channel2 = 1,								\
> +	.differential = 1,							\
> +	.scan_index = 0,							\
> +	.scan_type = {								\
> +		.sign = 'u',							\
> +		.realbits = 16,							\
> +		.storagebits = 16,						\
> +	},									\
> +}
> +
> +static const struct ad7405_chip_info ad7405_chip_info = {
> +		.name = "AD7405",
> +		.channel = {
> +			AD7405_IIO_CHANNEL,
> +		},
> +};
> +
> +static const struct ad7405_chip_info adum7701_chip_info = {
> +		.name = "ADUM7701",
> +		.channel = {
> +			AD7405_IIO_CHANNEL,
> +		},
> +};
> +
> +static const char * const ad7405_power_supplies[] = {
> +	"vdd1",	"vdd2",
> +};
> +
> +static int ad7405_probe(struct platform_device *pdev)
> +{
> +	const struct ad7405_chip_info *chip_info;
> +	struct device *dev = &pdev->dev;
> +	struct iio_dev *indio_dev;
> +	struct ad7405_state *st;
> +	struct clk *clk;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +
> +	ret = devm_mutex_init(dev, &st->lock);
> +	if (ret)
> +		return ret;
> +
> +	chip_info = device_get_match_data(dev);
> +	if (!chip_info)
> +		return dev_err_probe(dev, -EINVAL, "no chip info\n");
> +
> +	ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(ad7405_power_supplies),
> +					     ad7405_power_supplies);
> +
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to get and enable supplies");
> +
> +	clk = devm_clk_get_enabled(dev, NULL);
> +	if (IS_ERR(clk))
> +		return PTR_ERR(clk);
> +
> +	ret = devm_add_action_or_reset(dev, ad7405_clk_disable_unprepare, clk);

devm_clk_get_enabled() already make sure the clock is disabled when the dirver
is removed, so this is not needed.

> +	if (ret)
> +		return ret;
> +
> +	st->ref_frequency = clk_get_rate(clk);
> +	if (!(st->ref_frequency))

Inner () not needed.

> +		return -EINVAL;
> +
> +	ad7405_fill_samp_freq_table(st);
> +
> +	indio_dev->dev.parent = dev;
> +	indio_dev->name = chip_info->name;
> +	indio_dev->channels = chip_info->channel;
> +	indio_dev->num_channels = 1;
> +	indio_dev->info = &ad7405_iio_info;
> +
> +	st->back = devm_iio_backend_get(dev, NULL);
> +	if (IS_ERR(st->back))
> +		return dev_err_probe(dev, PTR_ERR(st->back),
> +				     "failed to get IIO backend");
> +
> +	ret = iio_backend_chan_enable(st->back, 0);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_iio_backend_request_buffer(dev, st->back, indio_dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_iio_backend_enable(dev, st->back);
> +	if (ret)
> +		return ret;
> +
> +	ret = ad7405_set_sampling_rate(indio_dev, &indio_dev->channels[0],
> +				       chip_info->max_rate);

max_rate is never set, so will always be 0.

> +	if (ret)
> +		return ret;
> +
> +	return devm_iio_device_register(dev, indio_dev);
> +}
> +
> +/* Match table for of_platform binding */
> +static const struct of_device_id ad7405_of_match[] = {
> +	{ .compatible = "adi,ad7405", .data = &ad7405_chip_info, },
> +	{ .compatible = "adi,adum7701", .data = &adum7701_chip_info, },
> +	{ .compatible = "adi,adum7702", .data = &adum7701_chip_info, },
> +	{ .compatible = "adi,adum7703", .data = &adum7701_chip_info, },
> +	{ /* end of list */ },

	{ }

We standardized on this style in the IIO subsystem.

> +};
> +MODULE_DEVICE_TABLE(of, ad7405_of_match);
> +
> +static struct platform_driver ad7405_driver = {
> +	.driver = {
> +		.name = "ad7405",
> +		.owner = THIS_MODULE,
> +		.of_match_table = ad7405_of_match,
> +	},
> +	.probe = ad7405_probe,
> +};
> +module_platform_driver(ad7405_driver);
> +
> +MODULE_AUTHOR("Dragos Bogdan <dragos.bogdan@analog.com>");
> +MODULE_AUTHOR("Pop Ioan Daniel <pop.ioan-daniel@analog.com>");
> +MODULE_DESCRIPTION("Analog Devices AD7405 driver");
> +MODULE_LICENSE("GPL");
> +MODULE_IMPORT_NS("IIO_BACKEND");

Re: [PATCH v2 4/4] iio: adc: ad7405: add ad7405 driver

[Jonathan Cameron]

> > +
> > +static const struct iio_info ad7405_iio_info = {
> > +	.read_raw = &ad7405_read_raw,
> > +	.write_raw = &ad7405_write_raw,
> > +	.read_avail = &ad7405_read_avail,
> > +};
> > +
> > +#define AD7405_IIO_CHANNEL {							\
> > +	.type = IIO_VOLTAGE,							\
> > +	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),		\
> > +	.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),	\  
> 
> Would it make more sense to use IIO_CHAN_INFO_OVERSAMPLING_RATIO for controlling
> the decimation rate and have IIO_CHAN_INFO_SAMP_FREQ be read-only?

My initial reaction to this was that we'd be not providing one of the longest
standing and user friendly(ish) interfaces.  However if it literally only affects
oversampling then indeed I think oversampling is the more informative interface.
Which is to say I started writing no then thought some more and ended up agreeing with
you ;)

As you say, a read only sampling frequency is fine.  We use those when it's controlled
by some outside factor (like a clock frequency) so userspace should in theory at least
cope fine with that being RO.

> Maybe also useful to have a read-only filter_type attribute to say that the
> backend is providing a sinc3 filter?

Nice to have perhaps.


J

Re: [PATCH v2 4/4] iio: adc: ad7405: add ad7405 driver

[kernel test robot]

Hi Pop,

kernel test robot noticed the following build warnings:

[auto build test WARNING on jic23-iio/togreg]
[also build test WARNING on linus/master v6.15-rc5 next-20250508]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Pop-Ioan-Daniel/iio-backend-update-iio_backend_oversampling_ratio_set/20250508-203339
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git togreg
patch link:    https://lore.kernel.org/r/20250508123107.3797042-5-pop.ioan-daniel%40analog.com
patch subject: [PATCH v2 4/4] iio: adc: ad7405: add ad7405 driver
config: m68k-randconfig-r123-20250509 (https://download.01.org/0day-ci/archive/20250509/202505091958.k0P7xNyC-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 13.3.0
reproduce: (https://download.01.org/0day-ci/archive/20250509/202505091958.k0P7xNyC-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505091958.k0P7xNyC-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> drivers/iio/adc/ad7405.c:19:20: sparse: sparse: symbol 'ad7405_dec_rates' was not declared. Should it be static?

vim +/ad7405_dec_rates +19 drivers/iio/adc/ad7405.c

    18	
  > 19	const unsigned int ad7405_dec_rates[] = {
    20		4096, 2048, 1024, 512, 256, 128, 64, 32,
    21	};
    22	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v2 4/4] iio: adc: ad7405: add ad7405 driver

[Jonathan Cameron]

On Thu, 8 May 2025 15:30:57 +0300
Pop Ioan Daniel <pop.ioan-daniel@analog.com> wrote:

> Add support for the AD7405/ADUM770x, a high performance isolated ADC,
> 1-channel, 16-bit with a second-order Σ-Δ modulator that converts an
> analog input signal into a high speed, single-bit data stream.
> 
> Signed-off-by: Pop Ioan Daniel <pop.ioan-daniel@analog.com>
Hi,

Just a few comments inline.  In particular I'd avoid the gcc specific
behaviour unless we have it documented somewhere in the kernel that
static flexible array instantiation is allowed.

Doesn't make sense here anyway just make it 1 element.

Jonathan

> diff --git a/drivers/iio/adc/ad7405.c b/drivers/iio/adc/ad7405.c
> new file mode 100644
> index 000000000000..5fe36ce61819
> --- /dev/null
> +++ b/drivers/iio/adc/ad7405.c
> @@ -0,0 +1,264 @@

> +
> +struct ad7405_chip_info {
> +	const char *name;
> +	unsigned int max_rate;
> +	struct iio_chan_spec channel[];
See below.

> +};

> +static int ad7405_read_avail(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     const int **vals, int *type, int *length,
> +			     long info)
> +{
> +	struct ad7405_state *st = iio_priv(indio_dev);
> +
> +	switch (info) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +			*vals = st->sample_frequency_tbl;
1 tab only.
> +			*length = ARRAY_SIZE(st->sample_frequency_tbl);
> +			*type = IIO_VAL_INT;
> +			return IIO_AVAIL_LIST;
> +	default:
> +			return -EINVAL;
> +	}
> +}

> +
> +static const struct ad7405_chip_info ad7405_chip_info = {
> +		.name = "AD7405",
> +		.channel = {
> +			AD7405_IIO_CHANNEL,
> +		},
> +};
> +
> +static const struct ad7405_chip_info adum7701_chip_info = {
> +		.name = "ADUM7701",

Convention here is 1 tab indent only.

> +		.channel = {
This will look nicer without the array of 1 thing going on.

Interesting corner of the c spec to use a flexible array member
for this. Definitely don't do that as I hate reading that spec to
check corners like this.  On this occasion I looked and could
not find an answer.  There is a gcc extension that makes this work
though.

> +			AD7405_IIO_CHANNEL,
> +		},
> +};