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120 lines
2.9 KiB
120 lines
2.9 KiB
// 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 <[email protected]> |
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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 <[email protected]>"); |
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MODULE_DESCRIPTION("Bosch BMA400 triaxial acceleration sensor (SPI)"); |
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MODULE_LICENSE("GPL");
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