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// SPDX-License-Identifier: GPL-2.0-only
/*
* SPI IIO driver for Bosch BMA400 triaxial acceleration sensor.
*
* Copyright 2020 Dan Robertson <dan@dlrobertson.com>
*
*/
#include <linux/bits.h>
#include <linux/init.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/spi/spi.h>
#include "bma400.h"
#define BMA400_MAX_SPI_READ 2
#define BMA400_SPI_READ_BUFFER_SIZE (BMA400_MAX_SPI_READ + 1)
static int bma400_regmap_spi_read(void *context,
const void *reg, size_t reg_size,
void *val, size_t val_size)
{
struct device *dev = context;
struct spi_device *spi = to_spi_device(dev);
u8 result[BMA400_SPI_READ_BUFFER_SIZE];
ssize_t status;
if (val_size > BMA400_MAX_SPI_READ)
return -EINVAL;
status = spi_write_then_read(spi, reg, 1, result, val_size + 1);
if (status)
return status;
/*
* From the BMA400 datasheet:
*
* > For a basic read operation two bytes have to be read and the first
* > has to be dropped and the second byte must be interpreted.
*/
memcpy(val, result + 1, val_size);
return 0;
}
static int bma400_regmap_spi_write(void *context, const void *data,
size_t count)
{
struct device *dev = context;
struct spi_device *spi = to_spi_device(dev);
return spi_write(spi, data, count);
}
static struct regmap_bus bma400_regmap_bus = {
.read = bma400_regmap_spi_read,
.write = bma400_regmap_spi_write,
.read_flag_mask = BIT(7),
.max_raw_read = BMA400_MAX_SPI_READ,
};
static int bma400_spi_probe(struct spi_device *spi)
{
const struct spi_device_id *id = spi_get_device_id(spi);
struct regmap *regmap;
unsigned int val;
int ret;
regmap = devm_regmap_init(&spi->dev, &bma400_regmap_bus,
&spi->dev, &bma400_regmap_config);
if (IS_ERR(regmap)) {
dev_err(&spi->dev, "failed to create regmap\n");
return PTR_ERR(regmap);
}
/*
* Per the bma400 datasheet, the first SPI read may
* return garbage. As the datasheet recommends, the
* chip ID register will be read here and checked
* again in the following probe.
*/
ret = regmap_read(regmap, BMA400_CHIP_ID_REG, &val);
if (ret)
dev_err(&spi->dev, "Failed to read chip id register\n");
return bma400_probe(&spi->dev, regmap, id->name);
}
static int bma400_spi_remove(struct spi_device *spi)
{
return bma400_remove(&spi->dev);
}
static const struct spi_device_id bma400_spi_ids[] = {
{ "bma400", 0 },
{ }
};
MODULE_DEVICE_TABLE(spi, bma400_spi_ids);
static const struct of_device_id bma400_of_spi_match[] = {
{ .compatible = "bosch,bma400" },
{ }
};
MODULE_DEVICE_TABLE(of, bma400_of_spi_match);
static struct spi_driver bma400_spi_driver = {
.driver = {
.name = "bma400",
.of_match_table = bma400_of_spi_match,
},
.probe = bma400_spi_probe,
.remove = bma400_spi_remove,
.id_table = bma400_spi_ids,
};
module_spi_driver(bma400_spi_driver);
MODULE_AUTHOR("Dan Robertson <dan@dlrobertson.com>");
MODULE_DESCRIPTION("Bosch BMA400 triaxial acceleration sensor (SPI)");
MODULE_LICENSE("GPL");
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