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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 | // 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, spi->irq, id->name); } 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, .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"); MODULE_IMPORT_NS(IIO_BMA400); |