1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 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 2 18 #define BMA400_SPI_READ_BUFFER_SIZE (BMA400_MAX_SPI_READ + 1) 19 20 static 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 first 40 * > 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 47 static 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 56 static 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 63 static 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 may 79 * return garbage. As the datasheet recommends, the 80 * chip ID register will be read here and checked 81 * 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 90 static const struct spi_device_id bma400_spi_ids[] = { 91 { "bma400", 0 }, 92 { } 93 }; 94 MODULE_DEVICE_TABLE(spi, bma400_spi_ids); 95 96 static const struct of_device_id bma400_of_spi_match[] = { 97 { .compatible = "bosch,bma400" }, 98 { } 99 }; 100 MODULE_DEVICE_TABLE(of, bma400_of_spi_match); 101 102 static 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 }; 110 111 module_spi_driver(bma400_spi_driver); 112 MODULE_AUTHOR("Dan Robertson <dan@dlrobertson.com>"); 113 MODULE_DESCRIPTION("Bosch BMA400 triaxial acceleration sensor (SPI)"); 114 MODULE_LICENSE("GPL"); 115 MODULE_IMPORT_NS(IIO_BMA400); 116