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Message-ID: <99b1155f-9c3f-4249-8f6c-f369decc2727@foss.st.com>
Date: Wed, 7 Aug 2024 09:40:51 +0200
From: Olivier MOYSAN <olivier.moysan@...s.st.com>
To: Jonathan Cameron <jic23@...nel.org>
CC: <fabrice.gasnier@...s.st.com>, Lars-Peter Clausen <lars@...afoo.de>,
Liam
Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
<linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 8/9] iio: add iio backend support to sd modulator
Hi Jonathan,
On 8/6/24 18:51, Jonathan Cameron wrote:
> On Tue, 30 Jul 2024 10:46:38 +0200
> Olivier Moysan <olivier.moysan@...s.st.com> wrote:
>
>> The legacy sd modulator driver registers the sigma delta modulator as
>> an IIO channel provider. This implementation is not convenient when the
>> SD modulator has to be cascaded with another IIO device. The scaling
>> information is distributed across devices, which makes it difficult to
>> report consistent scaling data on IIO devices.
>>
>> The solution is to expose these cascaded IIO devices as an aggregate
>> device, which report global scaling information.
>> Add IIO backend support to SD modulator to allow scaling information
>> management.
>>
>> Signed-off-by: Olivier Moysan <olivier.moysan@...s.st.com>
> I've applied this fixup given changes in the backend code that crossed
> with this.
>
> diff --git a/drivers/iio/adc/sd_adc_modulator.c b/drivers/iio/adc/sd_adc_modulator.c
> index 06f9c5cacd53..654b6a38b650 100644
> --- a/drivers/iio/adc/sd_adc_modulator.c
> +++ b/drivers/iio/adc/sd_adc_modulator.c
> @@ -74,6 +74,11 @@ static const struct iio_backend_ops sd_backend_ops = {
> .read_raw = iio_sd_mod_read,
> };
>
> +static const struct iio_backend_info sd_backend_info = {
> + .name = "sd-modulator",
> + .ops = &sd_backend_ops,
> +};
> +
> static int iio_sd_mod_register(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> @@ -131,7 +136,7 @@ static int iio_sd_mod_probe(struct platform_device *pdev)
> priv->vref_mv = ret / 1000;
> }
>
> - return devm_iio_backend_register(&pdev->dev, &sd_backend_ops, priv);
> + return devm_iio_backend_register(&pdev->dev, &sd_backend_info, priv);
> };
>
> Please give it a quick spin. Hopefully I didn't break anything.
>
> Jonathan
I did a quick check. All looks fine to me.
Thanks for the fixup and the merge.
Regards
Olivier
>
>> ---
>> drivers/iio/adc/Kconfig | 1 +
>> drivers/iio/adc/sd_adc_modulator.c | 92 +++++++++++++++++++++++++++++-
>> 2 files changed, 92 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
>> index bd028d59db63..43ff8182b2ea 100644
>> --- a/drivers/iio/adc/Kconfig
>> +++ b/drivers/iio/adc/Kconfig
>> @@ -1195,6 +1195,7 @@ config SD_ADC_MODULATOR
>> tristate "Generic sigma delta modulator"
>> select IIO_BUFFER
>> select IIO_TRIGGERED_BUFFER
>> + select IIO_BACKEND
>> help
>> Select this option to enables sigma delta modulator. This driver can
>> support generic sigma delta modulators.
>> diff --git a/drivers/iio/adc/sd_adc_modulator.c b/drivers/iio/adc/sd_adc_modulator.c
>> index 327cc2097f6c..06f9c5cacd53 100644
>> --- a/drivers/iio/adc/sd_adc_modulator.c
>> +++ b/drivers/iio/adc/sd_adc_modulator.c
>> @@ -6,11 +6,14 @@
>> * Author: Arnaud Pouliquen <arnaud.pouliquen@...com>.
>> */
>>
>> +#include <linux/iio/backend.h>
>> #include <linux/iio/iio.h>
>> #include <linux/iio/triggered_buffer.h>
>> #include <linux/module.h>
>> #include <linux/mod_devicetable.h>
>> #include <linux/platform_device.h>
>> +#include <linux/property.h>
>> +#include <linux/regulator/consumer.h>
>>
>> static const struct iio_info iio_sd_mod_iio_info;
>>
>> @@ -24,7 +27,54 @@ static const struct iio_chan_spec iio_sd_mod_ch = {
>> },
>> };
>>
>> -static int iio_sd_mod_probe(struct platform_device *pdev)
>> +struct iio_sd_backend_priv {
>> + struct regulator *vref;
>> + int vref_mv;
>> +};
>> +
>> +static int iio_sd_mod_enable(struct iio_backend *backend)
>> +{
>> + struct iio_sd_backend_priv *priv = iio_backend_get_priv(backend);
>> +
>> + if (priv->vref)diff --git a/drivers/iio/adc/sd_adc_modulator.c b/drivers/iio/adc/sd_adc_modulator.c
> index 06f9c5cacd53..654b6a38b650 100644
> --- a/drivers/iio/adc/sd_adc_modulator.c
> +++ b/drivers/iio/adc/sd_adc_modulator.c
> @@ -74,6 +74,11 @@ static const struct iio_backend_ops sd_backend_ops = {
> .read_raw = iio_sd_mod_read,
> };
>
> +static const struct iio_backend_info sd_backend_info = {
> + .name = "sd-modulator",
> + .ops = &sd_backend_ops,
> +};
> +
> static int iio_sd_mod_register(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> @@ -131,7 +136,7 @@ static int iio_sd_mod_probe(struct platform_device *pdev)
> priv->vref_mv = ret / 1000;
> }
>
> - return devm_iio_backend_register(&pdev->dev, &sd_backend_ops, priv);
> + return devm_iio_backend_register(&pdev->dev, &sd_backend_info, priv);
> };
>> + return regulator_enable(priv->vref);
>> +
>> + return 0;
>> +};
>> +
>> +static void iio_sd_mod_disable(struct iio_backend *backend)
>> +{
>> + struct iio_sd_backend_priv *priv = iio_backend_get_priv(backend);
>> +
>> + if (priv->vref)
>> + regulator_disable(priv->vref);
>> +};
>> +
>> +static int iio_sd_mod_read(struct iio_backend *backend, struct iio_chan_spec const *chan, int *val,
>> + int *val2, long mask)
>> +{
>> + struct iio_sd_backend_priv *priv = iio_backend_get_priv(backend);
>> +
>> + switch (mask) {
>> + case IIO_CHAN_INFO_SCALE:
>> + *val = priv->vref_mv;
>> + return IIO_VAL_INT;
>> +
>> + case IIO_CHAN_INFO_OFFSET:
>> + *val = 0;
>> + return IIO_VAL_INT;
>> + }
>> +
>> + return -EOPNOTSUPP;
>> +};
>> +
>> +static const struct iio_backend_ops sd_backend_ops = {
>> + .enable = iio_sd_mod_enable,
>> + .disable = iio_sd_mod_disable,
>> + .read_raw = iio_sd_mod_read,
>> +};
>> +
>> +static int iio_sd_mod_register(struct platform_device *pdev)
>> {
>> struct device *dev = &pdev->dev;
>> struct iio_dev *iio;
>> @@ -45,6 +95,45 @@ static int iio_sd_mod_probe(struct platform_device *pdev)
>> return devm_iio_device_register(&pdev->dev, iio);
>> }
>>
>> +static int iio_sd_mod_probe(struct platform_device *pdev)
>> +{
>> + struct device *dev = &pdev->dev;
>> + struct regulator *vref;
>> + struct iio_sd_backend_priv *priv;
>> + int ret;
>> +
>> + /* If sd modulator is not defined as an IIO backend device, fallback to legacy */
>> + if (!device_property_present(dev, "#io-backend-cells"))
>> + return iio_sd_mod_register(pdev);
>> +
>> + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>> + if (!priv)
>> + return -ENOMEM;
>> +
>> + /*
>> + * Get regulator reference if any, but don't enable regulator right now.
>> + * Rely on enable and disable callbacks to manage regulator power.
>> + */
>> + vref = devm_regulator_get_optional(dev, "vref");
>> + if (IS_ERR(vref)) {
>> + if (PTR_ERR(vref) != -ENODEV)
>> + return dev_err_probe(dev, PTR_ERR(vref), "Failed to get vref\n");
>> + } else {
>> + /*
>> + * Retrieve voltage right now, as regulator_get_voltage() provides it whatever
>> + * the state of the regulator.
>> + */
>> + ret = regulator_get_voltage(vref);
>> + if (ret < 0)
>> + return ret;
>> +
>> + priv->vref = vref;
>> + priv->vref_mv = ret / 1000;
>> + }
>> +
>> + return devm_iio_backend_register(&pdev->dev, &sd_backend_ops, priv);
>> +};
>> +
>> static const struct of_device_id sd_adc_of_match[] = {
>> { .compatible = "sd-modulator" },
>> { .compatible = "ads1201" },
>> @@ -65,3 +154,4 @@ module_platform_driver(iio_sd_mod_adc);
>> MODULE_DESCRIPTION("Basic sigma delta modulator");
>> MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@...com>");
>> MODULE_LICENSE("GPL v2");
>> +MODULE_IMPORT_NS(IIO_BACKEND);
>
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