On 2/7/25 2:09 PM, David Lechner wrote: > Add support for SPI offload to the ad4695 driver. SPI offload allows > sampling data at the max sample rate (500kSPS or 1MSPS). > > This is developed and tested against the ADI example FPGA design for > this family of ADCs [1]. > > [1]: http://analogdevicesinc.github.io/hdl/projects/ad469x_fmc/index.html > > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> > Reviewed-by: Nuno Sa <nuno.sa@xxxxxxxxxx> > Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx> > --- > ... > --- > drivers/iio/adc/Kconfig | 1 + > drivers/iio/adc/ad4695.c | 445 +++++++++++++++++++++++++++++++++++++++++++++-- > 2 files changed, 429 insertions(+), 17 deletions(-) > > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig > index 995b9cacbaa964d26424346120c139858f93cdcd..ec60b64c46e187e2be18ab1f8ca9e6f4f03299f9 100644 > --- a/drivers/iio/adc/Kconfig > +++ b/drivers/iio/adc/Kconfig > @@ -52,6 +52,7 @@ config AD4695 > tristate "Analog Device AD4695 ADC Driver" > depends on SPI > select IIO_BUFFER > + select IIO_BUFFER_DMAENGINE > select IIO_TRIGGERED_BUFFER > select REGMAP I missed adding select SPI_OFFLOAD Closes: https://lore.kernel.org/oe-kbuild-all/202502090910.ganYXEeF-lkp@xxxxxxxxx/ > help ... > +static int ad4695_offload_buffer_postenable(struct iio_dev *indio_dev) > +{ > + struct ad4695_state *st = iio_priv(indio_dev); > + struct spi_offload_trigger_config config = { > + .type = SPI_OFFLOAD_TRIGGER_DATA_READY, > + }; > + struct spi_transfer *xfer = &st->buf_read_xfer[0]; > + struct pwm_state state; > + u8 temp_chan_bit = st->chip_info->num_voltage_inputs; > + u8 num_slots = 0; > + u8 temp_en = 0; > + unsigned int bit; > + int ret; > + > + iio_for_each_active_channel(indio_dev, bit) { > + if (bit == temp_chan_bit) { > + temp_en = 1; > + continue; > + } > + > + ret = regmap_write(st->regmap, AD4695_REG_AS_SLOT(num_slots), > + FIELD_PREP(AD4695_REG_AS_SLOT_INX, bit)); > + if (ret) > + return ret; > + > + num_slots++; > + } > + > + /* > + * For non-offload, we could discard data to work around this > + * restriction, but with offload, that is not possible. > + */ > + if (num_slots < 2) { > + dev_err(&st->spi->dev, > + "At least two voltage channels must be enabled.\n"); > + return -EINVAL; > + } > + > + ret = regmap_update_bits(st->regmap, AD4695_REG_TEMP_CTRL, > + AD4695_REG_TEMP_CTRL_TEMP_EN, > + FIELD_PREP(AD4695_REG_TEMP_CTRL_TEMP_EN, > + temp_en)); > + if (ret) > + return ret; > + > + /* Each BUSY event means just one sample for one channel is ready. */ > + memset(xfer, 0, sizeof(*xfer)); > + xfer->offload_flags = SPI_OFFLOAD_XFER_RX_STREAM; > + /* Using 19 bits per word to allow for possible oversampling */ > + xfer->bits_per_word = 19; > + xfer->len = 4; > + > + spi_message_init_with_transfers(&st->buf_read_msg, xfer, 1); > + st->buf_read_msg.offload = st->offload; > + > + ret = spi_optimize_message(st->spi, &st->buf_read_msg); > + if (ret) > + return ret; > + > + /* > + * NB: technically, this is part the SPI offload trigger enable, but it > + * doesn't work to call it from the offload trigger enable callback > + * because it requires accessing the SPI bus. Calling it from the > + * trigger enable callback could cause a deadlock. > + */ > + ret = regmap_set_bits(st->regmap, AD4695_REG_GP_MODE, > + AD4695_REG_GP_MODE_BUSY_GP_EN); > + if (ret) > + goto err_unoptimize_message; > + > + ret = spi_offload_trigger_enable(st->offload, st->offload_trigger, > + &config); > + if (ret) > + goto err_disable_busy_output; > + > + ret = ad4695_enter_advanced_sequencer_mode(st, num_slots); > + if (ret) > + goto err_offload_trigger_disable; > + > + guard(mutex)(&st->cnv_pwm_lock); Apparently clang doesn't like this guard() after goto, so I'll have to figure out what to do about that. Probably need to add a helper function to avoid goto below from jumping out of scoped_guard(). https://lore.kernel.org/oe-kbuild-all/202502090806.KxEvxCZC-lkp@xxxxxxxxx/ > + pwm_get_state(st->cnv_pwm, &state); > + /* > + * PWM subsystem generally rounds down, so requesting 2x minimum high > + * time ensures that we meet the minimum high time in any case. > + */ > + state.duty_cycle = AD4695_T_CNVH_NS * 2; > + ret = pwm_apply_might_sleep(st->cnv_pwm, &state); > + if (ret) > + goto err_offload_exit_conversion_mode; > + > + return 0; > + > +err_offload_exit_conversion_mode: > + /* > + * We have to unwind in a different order to avoid triggering offload. > + * ad4695_exit_conversion_mode() triggers a conversion, so it has to be > + * done after spi_offload_trigger_disable(). > + */ > + spi_offload_trigger_disable(st->offload, st->offload_trigger); > + ad4695_exit_conversion_mode(st); > + goto err_disable_busy_output; > + > +err_offload_trigger_disable: > + spi_offload_trigger_disable(st->offload, st->offload_trigger); > + > +err_disable_busy_output: > + regmap_clear_bits(st->regmap, AD4695_REG_GP_MODE, > + AD4695_REG_GP_MODE_BUSY_GP_EN); > + > +err_unoptimize_message: > + spi_unoptimize_message(&st->buf_read_msg); > + > + return ret; > +}
