[PATCH v4 04/10] iio: adc: rzg2l_adc: Use adc-helpers

Matti Vaittinen
2025-02-24T18:33:38Z

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The new devm_iio_adc_device_alloc_chaninfo() -helper is intended to help
drivers avoid open-coding the for_each_node -loop for getting the
channel IDs. The helper provides standard way to detect the ADC channel
nodes (by the node name), and a standard way to convert the "reg",
"diff-channels", "single-channel" and the "common-mode-channel" to
channel identification numbers used in the struct iio_chan_spec.
Furthermore, the helper checks the ID is in range of 0 ... num-channels.

The original driver treated all found child nodes as channel nodes. The
new helper requires channel nodes to be named channel[@N]. This should
help avoid problems with devices which may contain also other but ADC
child nodes. Quick grep from arch/* with the rzg2l_adc's compatible
string didn't reveal any in-tree .dts with channel nodes named
othervice. Also, same grep shows all the .dts seem to have channel IDs
between 0..num of channels.

Use the new helper.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---
Revision history:
v3 => v4:
- Adapt to 'drop diff-channel support' changes to ADC-helpers
- select ADC helpers in the Kconfig
- Rebased to 6.14-rc3 => channel type can no longer come from the
template.

v2 => v3:
- New patch

I picked the rzg2l_adc in this series because it has a straightforward
approach for populating the struct iio_chan_spec. Only other member
in the stuct besides the .channel, which can't use a 'template' -data,
is the .datasheet_name. This makes the rzg2l_adc well suited for example
user of this new helper. I hope this patch helps to evaluate whether these
helpers are worth the hassle.

The change is compile tested only!! Testing before applying is highly
appreciated (as always!).
---
drivers/iio/adc/Kconfig | 1 +
drivers/iio/adc/rzg2l_adc.c | 38 +++++++++++++++++--------------------
2 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 37b70a65da6f..e4933de0c366 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1222,6 +1222,7 @@ config RICHTEK_RTQ6056
config RZG2L_ADC
tristate "Renesas RZ/G2L ADC driver"
depends on ARCH_RZG2L || COMPILE_TEST
+ select IIO_ADC_HELPER
help
Say yes here to build support for the ADC found in Renesas
RZ/G2L family.
diff --git a/drivers/iio/adc/rzg2l_adc.c b/drivers/iio/adc/rzg2l_adc.c
index 883c167c0670..51c87b1bdc98 100644
--- a/drivers/iio/adc/rzg2l_adc.c
+++ b/drivers/iio/adc/rzg2l_adc.c
@@ -11,6 +11,7 @@
#include <linux/cleanup.h>
#include <linux/completion.h>
#include <linux/delay.h>
+#include <linux/iio/adc-helpers.h>
#include <linux/iio/iio.h>
#include <linux/interrupt.h>
#include <linux/io.h>
@@ -324,21 +325,30 @@ static irqreturn_t rzg2l_adc_isr(int irq, void *dev_id)
return IRQ_HANDLED;
}

+static const struct iio_chan_spec rzg2l_adc_chan_template = {
+ .indexed = 1,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+};
+
static int rzg2l_adc_parse_properties(struct platform_device *pdev, struct rzg2l_adc *adc)
{
const struct rzg2l_adc_hw_params *hw_params = adc->hw_params;
struct iio_chan_spec *chan_array;
struct rzg2l_adc_data *data;
- unsigned int channel;
int num_channels;
- int ret;
u8 i;

data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;

- num_channels = device_get_child_node_count(&pdev->dev);
+ num_channels = devm_iio_adc_device_alloc_chaninfo_se(&pdev->dev,
+ &rzg2l_adc_chan_template,
+ hw_params->num_channels - 1,
+ &chan_array);
+ if (num_channels < 0)
+ return num_channels;
+
if (!num_channels)
return dev_err_probe(&pdev->dev, -ENODEV, "no channel children\n");

@@ -346,26 +356,11 @@ static int rzg2l_adc_parse_properties(struct platform_device *pdev, struct rzg2l
return dev_err_probe(&pdev->dev, -EINVAL,
"num of channel children out of range\n");

- chan_array = devm_kcalloc(&pdev->dev, num_channels, sizeof(*chan_array),
- GFP_KERNEL);
- if (!chan_array)
- return -ENOMEM;
-
- i = 0;
- device_for_each_child_node_scoped(&pdev->dev, fwnode) {
- ret = fwnode_property_read_u32(fwnode, "reg", &channel);
- if (ret)
- return ret;
-
- if (channel >= hw_params->num_channels)
- return -EINVAL;
+ for (i = 0; i < num_channels; i++) {
+ int channel = chan_array[i].channel;

- chan_array[i].type = rzg2l_adc_channels[channel].type;
- chan_array[i].indexed = 1;
- chan_array[i].channel = channel;
- chan_array[i].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
chan_array[i].datasheet_name = rzg2l_adc_channels[channel].name;
- i++;
+ chan_array[i].type = rzg2l_adc_channels[channel].type;
}

data->num_channels = num_channels;
@@ -626,3 +621,4 @@ module_platform_driver(rzg2l_adc_driver);
MODULE_AUTHOR("Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>");
MODULE_DESCRIPTION("Renesas RZ/G2L ADC driver");
MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS("IIO_DRIVER");
--
2.48.1

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