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Message-ID: <06e8f4f84731df9fc5d6f324e74fbd1bf83a81d5.1741610847.git.mazziesaccount@gmail.com>
Date: Mon, 10 Mar 2025 14:56:35 +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>, Chen-Yu Tsai <wens@...e.org>,
Jernej Skrabec <jernej.skrabec@...il.com>,
Samuel Holland <samuel@...lland.org>, Nuno Sa <nuno.sa@...log.com>,
David Lechner <dlechner@...libre.com>,
Javier Carrasco <javier.carrasco.cruz@...il.com>,
Matti Vaittinen <mazziesaccount@...il.com>,
Olivier Moysan <olivier.moysan@...s.st.com>,
Guillaume Stols <gstols@...libre.com>,
Dumitru Ceclan <mitrutzceclan@...il.com>,
Trevor Gamblin <tgamblin@...libre.com>,
Matteo Martelli <matteomartelli3@...il.com>,
Alisa-Dariana Roman <alisadariana@...il.com>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev
Subject: [PATCH v6 05/10] iio: adc: sun20i-gpadc: 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"
-properties to channel identification numbers, used in the struct
iio_chan_spec. Furthermore, the helper can optionally check the found
channel IDs are smaller than given maximum. This is useful for callers
which later use the IDs for example for indexing a channel data array.
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 sun20i-gpadc's compatible
string didn't reveal any in-tree .dts with channel nodes named
otherwise. Also, same grep shows all the in-tree .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:
v5 => v6:
- Commit message typofix
v4 => v5:
- Drop the diff-channel stuff from the commit message
v3 => v4:
- Adapt to 'drop diff-channel support' changes to ADC-helpers
- select ADC helpers in the Kconfig
v2 => v3:
- New patch
I picked the sun20i-gpadc in this series because it has a straightforward
approach for populating the struct iio_chan_spec. Everything else except
the .channel can use 'template'-data.
This makes the sun20i-gpadc well suited to be an 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!). Also, even though I tried to audit the dts
files for the reg-properties in the channel nodes, use of references
didn't make it easy. I can't guarantee I didn't miss anything.
---
drivers/iio/adc/Kconfig | 1 +
drivers/iio/adc/sun20i-gpadc-iio.c | 38 ++++++++++++------------------
2 files changed, 16 insertions(+), 23 deletions(-)
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index e4933de0c366..0993008a1586 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1357,6 +1357,7 @@ config SUN4I_GPADC
config SUN20I_GPADC
tristate "Allwinner D1/T113s/T507/R329 and similar GPADCs driver"
depends on ARCH_SUNXI || COMPILE_TEST
+ select IIO_ADC_HELPER
help
Say yes here to build support for Allwinner (D1, T113, T507 and R329)
SoCs GPADC. This ADC provides up to 16 channels.
diff --git a/drivers/iio/adc/sun20i-gpadc-iio.c b/drivers/iio/adc/sun20i-gpadc-iio.c
index 136b8d9c294f..bf1db2a3de9b 100644
--- a/drivers/iio/adc/sun20i-gpadc-iio.c
+++ b/drivers/iio/adc/sun20i-gpadc-iio.c
@@ -15,6 +15,7 @@
#include <linux/property.h>
#include <linux/reset.h>
+#include <linux/iio/adc-helpers.h>
#include <linux/iio/iio.h>
#define SUN20I_GPADC_DRIVER_NAME "sun20i-gpadc"
@@ -149,37 +150,27 @@ static void sun20i_gpadc_reset_assert(void *data)
reset_control_assert(rst);
}
+static const struct iio_chan_spec sun20i_gpadc_chan_template = {
+ .type = IIO_VOLTAGE,
+ .indexed = 1,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+};
+
static int sun20i_gpadc_alloc_channels(struct iio_dev *indio_dev,
struct device *dev)
{
- unsigned int channel;
- int num_channels, i, ret;
+ int num_channels;
struct iio_chan_spec *channels;
- num_channels = device_get_child_node_count(dev);
+ num_channels = devm_iio_adc_device_alloc_chaninfo_se(dev,
+ &sun20i_gpadc_chan_template, -1, &channels);
+ if (num_channels < 0)
+ return num_channels;
+
if (num_channels == 0)
return dev_err_probe(dev, -ENODEV, "no channel children\n");
- channels = devm_kcalloc(dev, num_channels, sizeof(*channels),
- GFP_KERNEL);
- if (!channels)
- return -ENOMEM;
-
- i = 0;
- device_for_each_child_node_scoped(dev, node) {
- ret = fwnode_property_read_u32(node, "reg", &channel);
- if (ret)
- return dev_err_probe(dev, ret, "invalid channel number\n");
-
- channels[i].type = IIO_VOLTAGE;
- channels[i].indexed = 1;
- channels[i].channel = channel;
- channels[i].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
- channels[i].info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
-
- i++;
- }
-
indio_dev->channels = channels;
indio_dev->num_channels = num_channels;
@@ -271,3 +262,4 @@ module_platform_driver(sun20i_gpadc_driver);
MODULE_DESCRIPTION("ADC driver for sunxi platforms");
MODULE_AUTHOR("Maksim Kiselev <bigunclemax@...il.com>");
MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_DRIVER");
--
2.48.1
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