From: Jonathan Santos Date: Mon, 23 Feb 2026 11:59:53 +0000 (-0300) Subject: iio: adc: ad7768-1: add support for SPI offload X-Git-Tag: v7.1-rc1~17^2~120^2~124 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6ea592a31be5a45c1e695df8e3907c97f2c5213b;p=thirdparty%2Flinux.git iio: adc: ad7768-1: add support for SPI offload The AD7768-1 family supports sampling rates up to 1 MSPS, which exceeds the capabilities of conventional triggered buffer operations due to SPI transaction overhead and interrupt latency. Add SPI offload support to enable hardware-accelerated data acquisition that bypasses software SPI transactions using continuous data streaming. Signed-off-by: Jonathan Santos Reviewed-by: David Lechner Signed-off-by: Jonathan Cameron --- diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig index c54788ca8d8e2..a9dedbb8eb461 100644 --- a/drivers/iio/adc/Kconfig +++ b/drivers/iio/adc/Kconfig @@ -418,8 +418,10 @@ config AD7768_1 select REGMAP_SPI select RATIONAL select IIO_BUFFER + select IIO_BUFFER_DMAENGINE select IIO_TRIGGER select IIO_TRIGGERED_BUFFER + select SPI_OFFLOAD help Say yes here to build support for Analog Devices AD7768-1 SPI simultaneously sampling sigma-delta analog to digital converter (ADC). diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c index b77523393a183..917a3a0380a1b 100644 --- a/drivers/iio/adc/ad7768-1.c +++ b/drivers/iio/adc/ad7768-1.c @@ -25,12 +25,15 @@ #include #include #include +#include +#include #include #include #include #include #include +#include #include #include #include @@ -161,6 +164,8 @@ enum ad7768_filter_regval { enum ad7768_scan_type { AD7768_SCAN_TYPE_NORMAL, AD7768_SCAN_TYPE_HIGH_SPEED, + AD7768_SCAN_TYPE_OFFLOAD_NORMAL, + AD7768_SCAN_TYPE_OFFLOAD_HIGH_SPEED, }; enum { @@ -266,6 +271,18 @@ static const struct iio_scan_type ad7768_scan_type[] = { .storagebits = 16, .endianness = IIO_BE, }, + [AD7768_SCAN_TYPE_OFFLOAD_NORMAL] = { + .sign = 's', + .realbits = 24, + .storagebits = 32, + .endianness = IIO_CPU, + }, + [AD7768_SCAN_TYPE_OFFLOAD_HIGH_SPEED] = { + .sign = 's', + .realbits = 16, + .storagebits = 32, + .endianness = IIO_CPU, + }, }; struct ad7768_chip_info { @@ -283,6 +300,8 @@ struct ad7768_chip_info { struct ad7768_state { struct spi_device *spi; + struct spi_offload *offload; + struct spi_offload_trigger *offload_trigger; struct regmap *regmap; struct regmap *regmap24; int vref_uv; @@ -306,6 +325,8 @@ struct ad7768_state { struct gpio_desc *gpio_reset; const char *labels[AD7768_MAX_CHANNELS]; struct gpio_chip gpiochip; + struct spi_transfer offload_xfer; + struct spi_message offload_msg; const struct ad7768_chip_info *chip; bool en_spi_sync; struct mutex pga_lock; /* protect device internal state (PGA) */ @@ -1119,6 +1140,10 @@ static int ad7768_get_current_scan_type(const struct iio_dev *indio_dev, { struct ad7768_state *st = iio_priv(indio_dev); + if (st->offload) + return st->oversampling_ratio == 8 ? + AD7768_SCAN_TYPE_OFFLOAD_HIGH_SPEED : AD7768_SCAN_TYPE_OFFLOAD_NORMAL; + return st->oversampling_ratio == 8 ? AD7768_SCAN_TYPE_HIGH_SPEED : AD7768_SCAN_TYPE_NORMAL; } @@ -1341,6 +1366,78 @@ static const struct iio_buffer_setup_ops ad7768_buffer_ops = { .predisable = &ad7768_buffer_predisable, }; +static int ad7768_offload_buffer_postenable(struct iio_dev *indio_dev) +{ + struct ad7768_state *st = iio_priv(indio_dev); + struct spi_offload_trigger_config config = { + .type = SPI_OFFLOAD_TRIGGER_DATA_READY, + }; + const struct iio_scan_type *scan_type; + unsigned int unused; + int ret; + + scan_type = iio_get_current_scan_type(indio_dev, &indio_dev->channels[0]); + if (IS_ERR(scan_type)) + return PTR_ERR(scan_type); + + st->offload_xfer.len = spi_bpw_to_bytes(scan_type->realbits); + st->offload_xfer.bits_per_word = scan_type->realbits; + st->offload_xfer.offload_flags = SPI_OFFLOAD_XFER_RX_STREAM; + + spi_message_init_with_transfers(&st->offload_msg, &st->offload_xfer, 1); + st->offload_msg.offload = st->offload; + + ret = spi_optimize_message(st->spi, &st->offload_msg); + if (ret) { + dev_err(&st->spi->dev, "failed to prepare offload, err: %d\n", ret); + return ret; + } + + /* + * Write a 1 to the LSB of the INTERFACE_FORMAT register to enter + * continuous read mode. Subsequent data reads do not require an + * initial 8-bit write to query the ADC_DATA register. + */ + ret = regmap_write(st->regmap, AD7768_REG_INTERFACE_FORMAT, 0x01); + if (ret) + goto err_unoptimize_message; + + ret = spi_offload_trigger_enable(st->offload, st->offload_trigger, + &config); + if (ret) + goto err_exit_continuous_read_mode; + + return 0; + +err_exit_continuous_read_mode: + regmap_read(st->regmap24, AD7768_REG24_ADC_DATA, &unused); + +err_unoptimize_message: + spi_unoptimize_message(&st->offload_msg); + + return ret; +} + +static int ad7768_offload_buffer_predisable(struct iio_dev *indio_dev) +{ + struct ad7768_state *st = iio_priv(indio_dev); + unsigned int unused; + + spi_offload_trigger_disable(st->offload, st->offload_trigger); + spi_unoptimize_message(&st->offload_msg); + + /* + * To exit continuous read mode, perform a single read of the ADC_DATA + * reg (0x2C), which allows further configuration of the device. + */ + return regmap_read(st->regmap24, AD7768_REG24_ADC_DATA, &unused); +} + +static const struct iio_buffer_setup_ops ad7768_offload_buffer_ops = { + .postenable = ad7768_offload_buffer_postenable, + .predisable = ad7768_offload_buffer_predisable, +}; + static int ad7768_set_trigger_state(struct iio_trigger *trig, bool enable) { struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig); @@ -1589,6 +1686,36 @@ static int ad7768_parse_aaf_gain(struct device *dev, struct ad7768_state *st) return 0; } +static bool ad7768_offload_trigger_match(struct spi_offload_trigger *trigger, + enum spi_offload_trigger_type type, + u64 *args, u32 nargs) +{ + if (type != SPI_OFFLOAD_TRIGGER_DATA_READY) + return false; + + /* Up to 2 args are allowed, but only 1 is used */ + if (nargs == 0 || nargs > 2 || args[0] != AD7768_TRIGGER_SOURCE_DRDY) + return false; + + return true; +} + +static int ad7768_offload_trigger_request(struct spi_offload_trigger *trigger, + enum spi_offload_trigger_type type, + u64 *args, u32 nargs) +{ + /* Should already be validated by match, but just in case */ + if (nargs == 0 || nargs > 2) + return -EINVAL; + + return 0; +} + +static const struct spi_offload_trigger_ops ad7768_offload_trigger_ops = { + .match = ad7768_offload_trigger_match, + .request = ad7768_offload_trigger_request, +}; + static const struct ad7768_chip_info ad7768_chip_info = { .name = "ad7768-1", .channel_spec = ad7768_channels, @@ -1626,10 +1753,51 @@ static const struct ad7768_chip_info adaq7769_chip_info = { .has_variable_aaf = true, }; +static const struct spi_offload_config ad7768_spi_offload_config = { + .capability_flags = SPI_OFFLOAD_CAP_TRIGGER | SPI_OFFLOAD_CAP_RX_STREAM_DMA, +}; + +static int ad7768_spi_offload_probe(struct iio_dev *indio_dev, + struct ad7768_state *st) +{ + struct device *dev = &st->spi->dev; + struct spi_offload_trigger_info trigger_info = { + .fwnode = dev_fwnode(dev), + .ops = &ad7768_offload_trigger_ops, + .priv = st, + }; + struct dma_chan *rx_dma; + int ret; + + ret = devm_spi_offload_trigger_register(dev, &trigger_info); + if (ret) + return dev_err_probe(dev, ret, "failed to register offload trigger\n"); + + st->offload_trigger = devm_spi_offload_trigger_get(dev, st->offload, + SPI_OFFLOAD_TRIGGER_DATA_READY); + if (IS_ERR(st->offload_trigger)) + return dev_err_probe(dev, PTR_ERR(st->offload_trigger), + "failed to get offload trigger\n"); + + rx_dma = devm_spi_offload_rx_stream_request_dma_chan(dev, st->offload); + if (IS_ERR(rx_dma)) + return dev_err_probe(dev, PTR_ERR(rx_dma), "failed to get offload RX DMA\n"); + + ret = devm_iio_dmaengine_buffer_setup_with_handle(dev, indio_dev, rx_dma, + IIO_BUFFER_DIRECTION_IN); + if (ret) + return dev_err_probe(dev, ret, "failed to setup offload RX DMA\n"); + + indio_dev->setup_ops = &ad7768_offload_buffer_ops; + + return 0; +} + static int ad7768_probe(struct spi_device *spi) { struct ad7768_state *st; struct iio_dev *indio_dev; + struct device *dev = &spi->dev; int ret; indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st)); @@ -1725,9 +1893,20 @@ static int ad7768_probe(struct spi_device *spi) if (ret) return ret; - ret = ad7768_triggered_buffer_alloc(indio_dev); - if (ret) - return ret; + st->offload = devm_spi_offload_get(dev, spi, &ad7768_spi_offload_config); + ret = PTR_ERR_OR_ZERO(st->offload); + if (ret == -ENODEV) { + /* If not using SPI offload, fall back to low speed usage */ + ret = ad7768_triggered_buffer_alloc(indio_dev); + if (ret) + return ret; + } else if (ret) { + return dev_err_probe(dev, ret, "failed to get SPI offload\n"); + } else { + ret = ad7768_spi_offload_probe(indio_dev, st); + if (ret) + return ret; + } return devm_iio_device_register(&spi->dev, indio_dev); } @@ -1763,3 +1942,4 @@ module_spi_driver(ad7768_driver); MODULE_AUTHOR("Stefan Popa "); MODULE_DESCRIPTION("Analog Devices AD7768-1 ADC driver"); MODULE_LICENSE("GPL v2"); +MODULE_IMPORT_NS("IIO_DMAENGINE_BUFFER");