linux-kernel - [PATCH v3 6/9] iio: adc: rzg2l

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Message-ID: <25c5d22f6f0cbd1355eee2e9d9103c3ee71cebdc.1739967040.git.mazziesaccount@gmail.com>
Date: Wed, 19 Feb 2025 14:31:38 +0200
From: Matti Vaittinen <mazziesaccount@...il.com>
To: Matti Vaittinen <mazziesaccount@...il.com>,
	Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
Cc: Jonathan Cameron <jic23@...nel.org>,
	Lars-Peter Clausen <lars@...afoo.de>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Matti Vaittinen <mazziesaccount@...il.com>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
	Chen-Yu Tsai <wens@...e.org>,
	Jernej Skrabec <jernej.skrabec@...il.com>,
	Samuel Holland <samuel@...lland.org>,
	Hugo Villeneuve <hvilleneuve@...onoff.com>,
	Nuno Sa <nuno.sa@...log.com>, David Lechner <dlechner@...libre.com>,
	Javier Carrasco <javier.carrasco.cruz@...il.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev
Subject: [PATCH v3 6/9] iio: adc: rzg2l_adc: Use adc-helpers

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@...il.com>

---
Revision history:
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/rzg2l_adc.c | 41 ++++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 21 deletions(-)

diff --git a/drivers/iio/adc/rzg2l_adc.c b/drivers/iio/adc/rzg2l_adc.c
index cd3a7e46ea53..3e1c74019785 100644
--- a/drivers/iio/adc/rzg2l_adc.c
+++ b/drivers/iio/adc/rzg2l_adc.c
@@ -11,6 +11,7 @@
 #include <linux/clk.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>
@@ -299,20 +300,34 @@ static irqreturn_t rzg2l_adc_isr(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static const struct iio_chan_spec rzg2l_adc_chan_template = {
+	.type = IIO_VOLTAGE,
+	.indexed = 1,
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+};
+
+static const struct iio_adc_props rzg2l_adc_chan_props = {
+	.required = IIO_ADC_CHAN_PROP_TYPE_REG,
+};
+
 static int rzg2l_adc_parse_properties(struct platform_device *pdev, struct rzg2l_adc *adc)
 {
 	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(&pdev->dev,
+					&rzg2l_adc_chan_template, &chan_array,
+					&rzg2l_adc_chan_props);
+
+	if (num_channels < 0)
+		return num_channels;
+
 	if (!num_channels) {
 		dev_err(&pdev->dev, "no channel children\n");
 		return -ENODEV;
@@ -323,26 +338,10 @@ static int rzg2l_adc_parse_properties(struct platform_device *pdev, struct rzg2l
 		return -EINVAL;
 	}
 
-	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 >= RZG2L_ADC_MAX_CHANNELS)
-			return -EINVAL;
+	for (i = 0; i < num_channels; i++) {
+		int channel = chan_array[i].channel;
 
-		chan_array[i].type = IIO_VOLTAGE;
-		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_channel_name[channel];
-		i++;
 	}
 
 	data->num_channels = num_channels;
-- 
2.48.1


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