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Message-ID: <20240806175106.09a53784@jic23-huawei>
Date: Tue, 6 Aug 2024 17:51:06 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Olivier Moysan <olivier.moysan@...s.st.com>
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
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
> ---
> 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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