path: root/drivers/iio/adc/stm32-dfsdm-adc.c

// SPDX-License-Identifier: GPL-2.0
/*
 * This file is the ADC part of the STM32 DFSDM driver
 *
 * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
 * Author: Arnaud Pouliquen <arnaud.pouliquen@st.com>.
 */

#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/iio/adc/stm32-dfsdm-adc.h>
#include <linux/iio/buffer.h>
#include <linux/iio/hw-consumer.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/timer/stm32-lptim-trigger.h>
#include <linux/iio/timer/stm32-timer-trigger.h>
#include <linux/iio/trigger.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>

#include "stm32-dfsdm.h"

#define DFSDM_DMA_BUFFER_SIZE (4 * PAGE_SIZE)

/* Conversion timeout */
#define DFSDM_TIMEOUT_US 100000
#define DFSDM_TIMEOUT (msecs_to_jiffies(DFSDM_TIMEOUT_US / 1000))

/* Oversampling attribute default */
#define DFSDM_DEFAULT_OVERSAMPLING  100

/* Oversampling max values */
#define DFSDM_MAX_INT_OVERSAMPLING 256
#define DFSDM_MAX_FL_OVERSAMPLING 1024

/* Limit filter output resolution to 31 bits. (i.e. sample range is +/-2^30) */
#define DFSDM_DATA_MAX BIT(30)
/*
 * Data are output as two's complement data in a 24 bit field.
 * Data from filters are in the range +/-2^(n-1)
 * 2^(n-1) maximum positive value cannot be coded in 2's complement n bits
 * An extra bit is required to avoid wrap-around of the binary code for 2^(n-1)
 * So, the resolution of samples from filter is actually