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