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/* SPDX-License-Identifier: GPL-2.0-only */
* Support code for Analog Devices Sigma-Delta ADCs
* Copyright 2012 Analog Devices Inc.
* Author: Lars-Peter Clausen <>
#ifndef __AD_SIGMA_DELTA_H__
#define __AD_SIGMA_DELTA_H__
enum ad_sigma_delta_mode {
* struct ad_sigma_delta_calib_data - Calibration data for Sigma Delta devices
* @mode: Calibration mode.
* @channel: Calibration channel.
struct ad_sd_calib_data {
unsigned int mode;
unsigned int channel;
struct ad_sigma_delta;
struct device;
struct iio_dev;
* struct ad_sigma_delta_info - Sigma Delta driver specific callbacks and options
* @set_channel: Will be called to select the current channel, may be NULL.
* @set_mode: Will be called to select the current mode, may be NULL.
* @postprocess_sample: Is called for each sampled data word, can be used to
* modify or drop the sample data, it, may be NULL.
* @has_registers: true if the device has writable and readable registers, false
* if there is just one read-only sample data shift register.
* @addr_shift: Shift of the register address in the communications register.
* @read_mask: Mask for the communications register having the read bit set.
* @data_reg: Address of the data register, if 0 the default address of 0x3 will
* be used.
* @irq_flags: flags for the interrupt used by the triggered buffer
struct ad_sigma_delta_info {
int (*set_channel)(struct ad_sigma_delta *, unsigned int channel);
int (*set_mode)(struct ad_sigma_delta *, enum ad_sigma_delta_mode mode);
int (*postprocess_sample)(struct ad_sigma_delta *, unsigned int raw_sample);
bool has_registers;
unsigned int addr_shift;
unsigned int read_mask;
unsigned int data_reg;
unsigned long irq_flags;
* struct ad_sigma_delta - Sigma Delta device struct
* @spi: The spi device associated with the Sigma Delta device.
* @trig: The IIO trigger associated with the Sigma Delta device.
* Most of the fields are private to the sigma delta library code and should not
* be accessed by individual drivers.
struct ad_sigma_delta {
struct spi_device *spi;
struct iio_trigger *trig;
/* private: */
struct completion completion;
bool irq_dis;
bool bus_locked;
bool keep_cs_asserted;
uint8_t comm;
const struct ad_sigma_delta_info *info;
* DMA (thus cache coherency maintenance) requires the
* transfer buffers to live in their own cache lines.
* 'tx_buf' is up to 32 bits.
* 'rx_buf' is up to 32 bits per sample + 64 bit timestamp,
* rounded to 16 bytes to take into account padding.
uint8_t tx_buf[4] ____cacheline_aligned;
uint8_t rx_buf[16] __aligned(8);
static inline int ad_sigma_delta_set_channel(struct ad_sigma_delta *sd,
unsigned int channel)
if (sd->info->set_channel)
return sd->info->set_channel(sd, channel);
return 0;
static inline int ad_sigma_delta_set_mode(struct ad_sigma_delta *sd,
unsigned int mode)
if (sd->info->set_mode)
return sd->info->set_mode(sd, mode);
return 0;
static inline int ad_sigma_delta_postprocess_sample(struct ad_sigma_delta *sd,
unsigned int raw_sample)
if (sd->info->postprocess_sample)
return sd->info->postprocess_sample(sd, raw_sample);
return 0;
void ad_sd_set_comm(struct ad_sigma_delta *sigma_delta, uint8_t comm);
int ad_sd_write_reg(struct ad_sigma_delta *sigma_delta, unsigned int reg,
unsigned int size, unsigned int val);
int ad_sd_read_reg(struct ad_sigma_delta *sigma_delta, unsigned int reg,
unsigned int size, unsigned int *val);
int ad_sd_reset(struct ad_sigma_delta *sigma_delta,
unsigned int reset_length);
int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
const struct iio_chan_spec *chan, int *val);
int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
unsigned int mode, unsigned int channel);
int ad_sd_calibrate_all(struct ad_sigma_delta *sigma_delta,
const struct ad_sd_calib_data *cd, unsigned int n);
int ad_sd_init(struct ad_sigma_delta *sigma_delta, struct iio_dev *indio_dev,
struct spi_device *spi, const struct ad_sigma_delta_info *info);
int devm_ad_sd_setup_buffer_and_trigger(struct device *dev, struct iio_dev *indio_dev);
int ad_sd_validate_trigger(struct iio_dev *indio_dev, struct iio_trigger *trig);