linux-kernel - Re: [PATCH v7 14/17] iio: adc: ad4695: Add support for SPI offload

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Message-ID: <67dc52c4-5252-40c3-b89e-8e46e3c2df27@baylibre.com>
Date: Fri, 17 Jan 2025 11:09:03 -0600
From: David Lechner <dlechner@...libre.com>
To: Angelo Dureghello <adureghello@...libre.com>
Cc: Mark Brown <broonie@...nel.org>, Jonathan Cameron <jic23@...nel.org>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Nuno Sá
 <nuno.sa@...log.com>, Uwe Kleine-König
 <ukleinek@...nel.org>, Michael Hennerich <Michael.Hennerich@...log.com>,
 Lars-Peter Clausen <lars@...afoo.de>, David Jander <david@...tonic.nl>,
 Martin Sperl <kernel@...tin.sperl.org>, linux-spi@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-iio@...r.kernel.org, linux-pwm@...r.kernel.org,
 Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: Re: [PATCH v7 14/17] iio: adc: ad4695: Add support for SPI offload

On 1/17/25 9:47 AM, Angelo Dureghello wrote:
> Hi,
> 
> noticed just one possible issue here, see below.
> 
> On 13.01.2025 15:00, David Lechner wrote:
>> Add support for SPI offload to the ad4695 driver. SPI offload allows
>> sampling data at the max sample rate (500kSPS or 1MSPS).
>>
>> This is developed and tested against the ADI example FPGA design for
>> this family of ADCs [1].
>>
>> [1]: http://analogdevicesinc.github.io/hdl/projects/ad469x_fmc/index.html
>>
>> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
>> Reviewed-by: Nuno Sa <nuno.sa@...log.com>
>> Signed-off-by: David Lechner <dlechner@...libre.com>
>> ---
>>
>> v7 changes: none
>>
>> v6 changes:
>> * Fixed use of c++ style comments
>> * Moved static const struct definition out of probe function
>> * Changes bits_per_word to always be 19 for future oversampling
>>   compatibility (Trevor is working on implementing oversampling support
>>   on top of this patch, so we have high confidence this is the correct
>>   thing to do)
>> * Fixed wrong xfer->len
>>
>> v5 changes:
>> * Register SCLK speed handling has been split out into a separate series.
>> * Add sampling_frequency_available attribute.
>> * Limit max allowed sampling frequency based on chip info.
>> * Expand explanations of offload enable/disable ordering requirements.
>> * Finish TODO to use macros for phandle arg values.
>> * Don't use dev_info() when falling back to non-offload operation.
>> * Update to accommodate changes in other patches in this series.
>>
>> v4 changes: new patch in v4
>> ---
>>  drivers/iio/adc/Kconfig  |   1 +
>>  drivers/iio/adc/ad4695.c | 445 +++++++++++++++++++++++++++++++++++++++++++++--
>>  2 files changed, 429 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
>> index 995b9cacbaa964d26424346120c139858f93cdcd..ec60b64c46e187e2be18ab1f8ca9e6f4f03299f9 100644
>> --- a/drivers/iio/adc/Kconfig
>> +++ b/drivers/iio/adc/Kconfig
>> @@ -52,6 +52,7 @@ config AD4695
>>  	tristate "Analog Device AD4695 ADC Driver"
>>  	depends on SPI
>>  	select IIO_BUFFER
>> +	select IIO_BUFFER_DMAENGINE
>>  	select IIO_TRIGGERED_BUFFER
>>  	select REGMAP
>>  	help
>> diff --git a/drivers/iio/adc/ad4695.c b/drivers/iio/adc/ad4695.c
>> index 13cf01d35301be40369571e7dd2aeac1a8148d15..c8cd73d19e869f11999608f61df5724d329b4427 100644
>> --- a/drivers/iio/adc/ad4695.c
>> +++ b/drivers/iio/adc/ad4695.c
>> @@ -19,14 +19,19 @@
>>  #include <linux/device.h>
>>  #include <linux/err.h>
>>  #include <linux/gpio/consumer.h>
>> +#include <linux/iio/buffer-dmaengine.h>
>>  #include <linux/iio/buffer.h>
>>  #include <linux/iio/iio.h>
>>  #include <linux/iio/triggered_buffer.h>
>>  #include <linux/iio/trigger_consumer.h>
>>  #include <linux/minmax.h>
>> +#include <linux/mutex.h>
>>  #include <linux/property.h>
>> +#include <linux/pwm.h>
>>  #include <linux/regmap.h>
>>  #include <linux/regulator/consumer.h>
>> +#include <linux/spi/offload/consumer.h>
>> +#include <linux/spi/offload/provider.h>
>>  #include <linux/spi/spi.h>
>>  #include <linux/units.h>
> 
> ...
> 
>> +static int ad4695_offload_trigger_request(struct spi_offload_trigger *trigger,
>> +					  enum spi_offload_trigger_type type,
>> +					  u64 *args, u32 nargs)
>> +{
>> +	struct ad4695_state *st = spi_offload_trigger_get_priv(trigger);
>> +
>> +	/* Should already be validated by match, but just in case. */
>> +	if (nargs != 2)
>> +		return -EINVAL;
>> +
>> +	/* DT tells us if BUSY event uses GP0 or GP3. */
>> +	if (args[1] == AD4695_TRIGGER_PIN_GP3)
>> +		return regmap_set_bits(st->regmap, AD4695_REG_GP_MODE,
>> +				       AD4695_REG_GP_MODE_BUSY_GP_SEL);
>> +
>> +	return regmap_clear_bits(st->regmap, AD4695_REG_GPIO_CTRL,
>> +				 AD4695_REG_GP_MODE_BUSY_GP_SEL);
> 
> This should probably be:
>          
>         return regmap_clear_bits(st->regmap, AD4695_REG_GPIO_MODE,
>                                  AD4695_REG_GP_MODE_BUSY_GP_SEL);
> 

Indeed, thanks! Hopefully we won't need a v8 and Jonathan can fix while
applying. :-)

>> +}
>> +
> 
> Regards,
> angelo
>