116 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * SPI IIO driver for Bosch BMA400 triaxial acceleration sensor.4 *5 * Copyright 2020 Dan Robertson <dan@dlrobertson.com>6 *7 */8#include <linux/bits.h>9#include <linux/init.h>10#include <linux/mod_devicetable.h>11#include <linux/module.h>12#include <linux/regmap.h>13#include <linux/spi/spi.h>14 15#include "bma400.h"16 17#define BMA400_MAX_SPI_READ 218#define BMA400_SPI_READ_BUFFER_SIZE (BMA400_MAX_SPI_READ + 1)19 20static int bma400_regmap_spi_read(void *context,21 const void *reg, size_t reg_size,22 void *val, size_t val_size)23{24 struct device *dev = context;25 struct spi_device *spi = to_spi_device(dev);26 u8 result[BMA400_SPI_READ_BUFFER_SIZE];27 ssize_t status;28 29 if (val_size > BMA400_MAX_SPI_READ)30 return -EINVAL;31 32 status = spi_write_then_read(spi, reg, 1, result, val_size + 1);33 if (status)34 return status;35 36 /*37 * From the BMA400 datasheet:38 *39 * > For a basic read operation two bytes have to be read and the first40 * > has to be dropped and the second byte must be interpreted.41 */42 memcpy(val, result + 1, val_size);43 44 return 0;45}46 47static int bma400_regmap_spi_write(void *context, const void *data,48 size_t count)49{50 struct device *dev = context;51 struct spi_device *spi = to_spi_device(dev);52 53 return spi_write(spi, data, count);54}55 56static const struct regmap_bus bma400_regmap_bus = {57 .read = bma400_regmap_spi_read,58 .write = bma400_regmap_spi_write,59 .read_flag_mask = BIT(7),60 .max_raw_read = BMA400_MAX_SPI_READ,61};62 63static int bma400_spi_probe(struct spi_device *spi)64{65 const struct spi_device_id *id = spi_get_device_id(spi);66 struct regmap *regmap;67 unsigned int val;68 int ret;69 70 regmap = devm_regmap_init(&spi->dev, &bma400_regmap_bus,71 &spi->dev, &bma400_regmap_config);72 if (IS_ERR(regmap)) {73 dev_err(&spi->dev, "failed to create regmap\n");74 return PTR_ERR(regmap);75 }76 77 /*78 * Per the bma400 datasheet, the first SPI read may79 * return garbage. As the datasheet recommends, the80 * chip ID register will be read here and checked81 * again in the following probe.82 */83 ret = regmap_read(regmap, BMA400_CHIP_ID_REG, &val);84 if (ret)85 dev_err(&spi->dev, "Failed to read chip id register\n");86 87 return bma400_probe(&spi->dev, regmap, spi->irq, id->name);88}89 90static const struct spi_device_id bma400_spi_ids[] = {91 { "bma400", 0 },92 { }93};94MODULE_DEVICE_TABLE(spi, bma400_spi_ids);95 96static const struct of_device_id bma400_of_spi_match[] = {97 { .compatible = "bosch,bma400" },98 { }99};100MODULE_DEVICE_TABLE(of, bma400_of_spi_match);101 102static struct spi_driver bma400_spi_driver = {103 .driver = {104 .name = "bma400",105 .of_match_table = bma400_of_spi_match,106 },107 .probe = bma400_spi_probe,108 .id_table = bma400_spi_ids,109};110 111module_spi_driver(bma400_spi_driver);112MODULE_AUTHOR("Dan Robertson <dan@dlrobertson.com>");113MODULE_DESCRIPTION("Bosch BMA400 triaxial acceleration sensor (SPI)");114MODULE_LICENSE("GPL");115MODULE_IMPORT_NS(IIO_BMA400);116