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Thu, 20 Mar 2025 01:21:50 -0700 (PDT) Date: Thu, 20 Mar 2025 10:21:45 +0200 From: Matti Vaittinen To: Matti Vaittinen , Matti Vaittinen Cc: Jonathan Cameron , Lars-Peter Clausen , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , Nuno Sa , David Lechner , Javier Carrasco , Matti Vaittinen , Olivier Moysan , Guillaume Stols , Dumitru Ceclan , Trevor Gamblin , Matteo Martelli , Alisa-Dariana Roman , Andy Shevchenko , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev Subject: [PATCH v9 5/8] iio: adc: sun20i-gpadc: Use adc-helpers Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250320_012154_624580_812D07F9 X-CRM114-Status: GOOD ( 24.80 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The new devm_iio_adc_device_alloc_chaninfo_se() -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 Reviewed-by: Andy Shevchenko --- NOTE: This change now drops a print "no channel children" which used to be printed if no channel nodes were found. It also changes the return value from -ENODEV to -ENOENT. Revision history: v8 => - No changes v7 => v8: - drop explicit "no channels check". It is now done inside the devm_iio_adc_device_alloc_chaninfo_se(). v6 => v7: - Fix function name in the commit message 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 | 39 +++++++++++------------------- 2 files changed, 15 insertions(+), 25 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..2428ea69d676 100644 --- a/drivers/iio/adc/sun20i-gpadc-iio.c +++ b/drivers/iio/adc/sun20i-gpadc-iio.c @@ -15,6 +15,7 @@ #include #include +#include #include #define SUN20I_GPADC_DRIVER_NAME "sun20i-gpadc" @@ -149,36 +150,23 @@ 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); - 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++; - } + num_channels = devm_iio_adc_device_alloc_chaninfo_se(dev, + &sun20i_gpadc_chan_template, -1, &channels); + if (num_channels < 0) + return num_channels; indio_dev->channels = channels; indio_dev->num_channels = num_channels; @@ -271,3 +259,4 @@ module_platform_driver(sun20i_gpadc_driver); MODULE_DESCRIPTION("ADC driver for sunxi platforms"); MODULE_AUTHOR("Maksim Kiselev "); MODULE_LICENSE("GPL"); +MODULE_IMPORT_NS("IIO_DRIVER");