drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c

Source file repositories/reference/linux-study-clean/drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c

File Facts

System
Linux kernel
Corpus path
drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c
Extension
.c
Size
5238 bytes
Lines
202
Domain
Driver Families
Bucket
drivers/iio
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2019 TDK-InvenSense, Inc.
 */

#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/regmap.h>
#include <linux/delay.h>

#include "inv_mpu_aux.h"
#include "inv_mpu_iio.h"

/*
 * i2c master auxiliary bus transfer function.
 * Requires the i2c operations to be correctly setup before.
 * Disables SLV0 and checks for NACK status internally.
 * Assumes that only SLV0 is used for transfers.
 */
static int inv_mpu_i2c_master_xfer(const struct inv_mpu6050_state *st)
{
	/* use 50hz frequency for xfer */
	const unsigned int freq = 50;
	const unsigned int period_ms = 1000 / freq;
	uint8_t d;
	unsigned int user_ctrl;
	int ret;
	unsigned int status;

	/* set sample rate */
	d = INV_MPU6050_FIFO_RATE_TO_DIVIDER(freq);
	ret = regmap_write(st->map, st->reg->sample_rate_div, d);
	if (ret)
		return ret;

	/* start i2c master */
	user_ctrl = st->chip_config.user_ctrl | INV_MPU6050_BIT_I2C_MST_EN;
	ret = regmap_write(st->map, st->reg->user_ctrl, user_ctrl);
	if (ret)
		goto error_restore_rate;

	/* wait for xfer: 1 period + half-period margin */
	msleep(period_ms + period_ms / 2);

	/* stop i2c master */
	user_ctrl = st->chip_config.user_ctrl;
	ret = regmap_write(st->map, st->reg->user_ctrl, user_ctrl);
	if (ret)
		goto error_stop_i2c;

	/* restore sample rate */
	d = st->chip_config.divider;
	ret = regmap_write(st->map, st->reg->sample_rate_div, d);
	if (ret)
		goto error_restore_rate;

	/* disable i2c slave */
	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
	if (ret)
		goto error_disable_i2c;

	/* check i2c status */
	ret = regmap_read(st->map, INV_MPU6050_REG_I2C_MST_STATUS, &status);
	if (ret)
		return ret;

	if (status & INV_MPU6050_BIT_I2C_SLV0_NACK)
		return -EIO;

	return 0;

error_stop_i2c:
	regmap_write(st->map, st->reg->user_ctrl, st->chip_config.user_ctrl);
error_restore_rate:
	regmap_write(st->map, st->reg->sample_rate_div, st->chip_config.divider);
error_disable_i2c:
	regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
	return ret;
}

/**
 * inv_mpu_aux_init() - init i2c auxiliary bus
 * @st: driver internal state
 *
 * Returns 0 on success, a negative error code otherwise.
 */
int inv_mpu_aux_init(const struct inv_mpu6050_state *st)
{
	unsigned int val;
	int ret;

Annotation

Implementation Notes