From: David Lechner Date: Fri, 2 May 2025 15:42:16 +0000 (-0500) Subject: iio: adc: ad7606_spi: add offload scan mask check X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=017294e5a68ab2d09b380f912b30d36fc81edaa1;p=linux-2.6-microblaze.git iio: adc: ad7606_spi: add offload scan mask check Validate the scan mask when SPI offloading is being used. Since this family of ADCs is simultaneous sampling, there isn't a way to selectively disable channels when reading sample data. (Technically, AD7616 has a sequencer so the driver could have some control, but that is for another day). For "regular" IIO triggered buffer reads, this isn't a problem and the IIO core will demux the data and ignore data from disabled channels. However, since SPI offloading is done completely in hardware, we don't have a way to do the same. So before this patch, if less than all channels were enabled, the data would be misplaced in the buffer. By adding a check in update_scan_mode, we can fail to enable the buffer instead of having bad data returned to userspace. Fixes: e96d35faf357 ("iio: adc: ad7606: add SPI offload support") Signed-off-by: David Lechner Reviewed-by: Andy Shevchenko Reviewed-by: Nuno Sá Link: https://patch.msgid.link/20250502-iio-adc-ad7606_spi-fix-offload-scan-mask-check-v2-1-e70c6d71baa3@baylibre.com Signed-off-by: Jonathan Cameron --- diff --git a/drivers/iio/adc/ad7606_spi.c b/drivers/iio/adc/ad7606_spi.c index 997be483ebb9..5b5b4677273b 100644 --- a/drivers/iio/adc/ad7606_spi.c +++ b/drivers/iio/adc/ad7606_spi.c @@ -5,6 +5,7 @@ * Copyright 2011 Analog Devices Inc. */ +#include #include #include #include @@ -329,19 +330,44 @@ static int ad7606_spi_offload_probe(struct device *dev, return 0; } +static int ad7606_spi_update_scan_mode(struct iio_dev *indio_dev, + const unsigned long *scan_mask) +{ + struct ad7606_state *st = iio_priv(indio_dev); + + if (st->offload_en) { + unsigned int num_adc_ch = st->chip_info->num_adc_channels; + + /* + * SPI offload requires that all channels are enabled since + * there isn't a way to selectively disable channels that get + * read (this is simultaneous sampling ADC) and the DMA buffer + * has no way of demuxing the data to filter out unwanted + * channels. + */ + if (bitmap_weight(scan_mask, num_adc_ch) != num_adc_ch) + return -EINVAL; + } + + return 0; +} + static const struct ad7606_bus_ops ad7606_spi_bops = { .offload_config = ad7606_spi_offload_probe, .read_block = ad7606_spi_read_block, + .update_scan_mode = ad7606_spi_update_scan_mode, }; static const struct ad7606_bus_ops ad7607_spi_bops = { .offload_config = ad7606_spi_offload_probe, .read_block = ad7606_spi_read_block14to16, + .update_scan_mode = ad7606_spi_update_scan_mode, }; static const struct ad7606_bus_ops ad7608_spi_bops = { .offload_config = ad7606_spi_offload_probe, .read_block = ad7606_spi_read_block18to32, + .update_scan_mode = ad7606_spi_update_scan_mode, }; static const struct ad7606_bus_ops ad7616_spi_bops = { @@ -350,6 +376,7 @@ static const struct ad7606_bus_ops ad7616_spi_bops = { .reg_read = ad7606_spi_reg_read, .reg_write = ad7606_spi_reg_write, .rd_wr_cmd = ad7616_spi_rd_wr_cmd, + .update_scan_mode = ad7606_spi_update_scan_mode, }; static const struct ad7606_bus_ops ad7606b_spi_bops = { @@ -359,6 +386,7 @@ static const struct ad7606_bus_ops ad7606b_spi_bops = { .reg_write = ad7606_spi_reg_write, .rd_wr_cmd = ad7606b_spi_rd_wr_cmd, .sw_mode_config = ad7606b_sw_mode_config, + .update_scan_mode = ad7606_spi_update_scan_mode, }; static const struct ad7606_bus_ops ad7606c_18_spi_bops = { @@ -368,6 +396,7 @@ static const struct ad7606_bus_ops ad7606c_18_spi_bops = { .reg_write = ad7606_spi_reg_write, .rd_wr_cmd = ad7606b_spi_rd_wr_cmd, .sw_mode_config = ad7606b_sw_mode_config, + .update_scan_mode = ad7606_spi_update_scan_mode, }; static const struct ad7606_bus_info ad7605_4_bus_info = {