drivers/iio/pressure/bmp280-spi.c

Source file repositories/reference/linux-study-clean/drivers/iio/pressure/bmp280-spi.c

File Facts

System
Linux kernel
Corpus path
drivers/iio/pressure/bmp280-spi.c
Extension
.c
Size
4065 bytes
Lines
146
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-only
/*
 * SPI interface for the BMP280 driver
 *
 * Inspired by the older BMP085 driver drivers/misc/bmp085-spi.c
 */
#include <linux/bits.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/spi/spi.h>

#include "bmp280.h"

static int bmp280_regmap_spi_write(void *context, const void *data,
				   size_t count)
{
	struct spi_device *spi = to_spi_device(context);
	u8 buf[2];

	memcpy(buf, data, 2);
	/*
	 * The SPI register address (= full register address without bit 7) and
	 * the write command (bit7 = RW = '0')
	 */
	buf[0] &= ~0x80;

	return spi_write_then_read(spi, buf, 2, NULL, 0);
}

static int bmp280_regmap_spi_read(void *context, const void *reg,
				  size_t reg_size, void *val, size_t val_size)
{
	struct spi_device *spi = to_spi_device(context);

	return spi_write_then_read(spi, reg, reg_size, val, val_size);
}

static int bmp380_regmap_spi_read(void *context, const void *reg,
				  size_t reg_size, void *val, size_t val_size)
{
	struct spi_device *spi = to_spi_device(context);
	u8 rx_buf[BME280_BURST_READ_BYTES + 1];
	ssize_t status;

	if (val_size > BME280_BURST_READ_BYTES)
		return -EINVAL;

	/*
	 * According to the BMP3xx datasheets, for a basic SPI read operation,
	 * the first byte needs to be dropped and the rest are the requested
	 * data.
	 */
	status = spi_write_then_read(spi, reg, 1, rx_buf, val_size + 1);
	if (status)
		return status;

	memcpy(val, rx_buf + 1, val_size);

	return 0;
}

static const struct regmap_bus bmp280_regmap_bus = {
	.write = bmp280_regmap_spi_write,
	.read = bmp280_regmap_spi_read,
	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
	.val_format_endian_default = REGMAP_ENDIAN_BIG,
};

static const struct regmap_bus bmp380_regmap_bus = {
	.write = bmp280_regmap_spi_write,
	.read = bmp380_regmap_spi_read,
	.read_flag_mask = BIT(7),
	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
	.val_format_endian_default = REGMAP_ENDIAN_BIG,
};

static int bmp280_spi_probe(struct spi_device *spi)
{
	const struct spi_device_id *id = spi_get_device_id(spi);
	const struct bmp280_chip_info *chip_info;
	struct regmap_bus const *bmp_regmap_bus;
	struct regmap *regmap;

	chip_info = spi_get_device_match_data(spi);

	if (chip_info->spi_read_extra_byte)
		bmp_regmap_bus = &bmp380_regmap_bus;
	else
		bmp_regmap_bus = &bmp280_regmap_bus;

Annotation

Implementation Notes