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, txbuf: reg, n_tx: 1, rxbuf: result, n_rx: 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, buf: data, len: count); |
54 | } |
55 | |
56 | static 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(sdev: 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(ptr: regmap)) { |
73 | dev_err(&spi->dev, "failed to create regmap\n" ); |
74 | return PTR_ERR(ptr: 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(map: regmap, BMA400_CHIP_ID_REG, val: &val); |
84 | if (ret) |
85 | dev_err(&spi->dev, "Failed to read chip id register\n" ); |
86 | |
87 | return bma400_probe(dev: &spi->dev, regmap, irq: spi->irq, name: 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 | |