1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * SPI IIO driver for Bosch BMA400 triaxial acceleration sensor.
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright 2020 Dan Robertson <dan@dlrobertson.com>
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun */
8*4882a593Smuzhiyun #include <linux/bits.h>
9*4882a593Smuzhiyun #include <linux/init.h>
10*4882a593Smuzhiyun #include <linux/mod_devicetable.h>
11*4882a593Smuzhiyun #include <linux/module.h>
12*4882a593Smuzhiyun #include <linux/regmap.h>
13*4882a593Smuzhiyun #include <linux/spi/spi.h>
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun #include "bma400.h"
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun #define BMA400_MAX_SPI_READ 2
18*4882a593Smuzhiyun #define BMA400_SPI_READ_BUFFER_SIZE (BMA400_MAX_SPI_READ + 1)
19*4882a593Smuzhiyun
bma400_regmap_spi_read(void * context,const void * reg,size_t reg_size,void * val,size_t val_size)20*4882a593Smuzhiyun static int bma400_regmap_spi_read(void *context,
21*4882a593Smuzhiyun const void *reg, size_t reg_size,
22*4882a593Smuzhiyun void *val, size_t val_size)
23*4882a593Smuzhiyun {
24*4882a593Smuzhiyun struct device *dev = context;
25*4882a593Smuzhiyun struct spi_device *spi = to_spi_device(dev);
26*4882a593Smuzhiyun u8 result[BMA400_SPI_READ_BUFFER_SIZE];
27*4882a593Smuzhiyun ssize_t status;
28*4882a593Smuzhiyun
29*4882a593Smuzhiyun if (val_size > BMA400_MAX_SPI_READ)
30*4882a593Smuzhiyun return -EINVAL;
31*4882a593Smuzhiyun
32*4882a593Smuzhiyun status = spi_write_then_read(spi, reg, 1, result, val_size + 1);
33*4882a593Smuzhiyun if (status)
34*4882a593Smuzhiyun return status;
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun /*
37*4882a593Smuzhiyun * From the BMA400 datasheet:
38*4882a593Smuzhiyun *
39*4882a593Smuzhiyun * > For a basic read operation two bytes have to be read and the first
40*4882a593Smuzhiyun * > has to be dropped and the second byte must be interpreted.
41*4882a593Smuzhiyun */
42*4882a593Smuzhiyun memcpy(val, result + 1, val_size);
43*4882a593Smuzhiyun
44*4882a593Smuzhiyun return 0;
45*4882a593Smuzhiyun }
46*4882a593Smuzhiyun
bma400_regmap_spi_write(void * context,const void * data,size_t count)47*4882a593Smuzhiyun static int bma400_regmap_spi_write(void *context, const void *data,
48*4882a593Smuzhiyun size_t count)
49*4882a593Smuzhiyun {
50*4882a593Smuzhiyun struct device *dev = context;
51*4882a593Smuzhiyun struct spi_device *spi = to_spi_device(dev);
52*4882a593Smuzhiyun
53*4882a593Smuzhiyun return spi_write(spi, data, count);
54*4882a593Smuzhiyun }
55*4882a593Smuzhiyun
56*4882a593Smuzhiyun static struct regmap_bus bma400_regmap_bus = {
57*4882a593Smuzhiyun .read = bma400_regmap_spi_read,
58*4882a593Smuzhiyun .write = bma400_regmap_spi_write,
59*4882a593Smuzhiyun .read_flag_mask = BIT(7),
60*4882a593Smuzhiyun .max_raw_read = BMA400_MAX_SPI_READ,
61*4882a593Smuzhiyun };
62*4882a593Smuzhiyun
bma400_spi_probe(struct spi_device * spi)63*4882a593Smuzhiyun static int bma400_spi_probe(struct spi_device *spi)
64*4882a593Smuzhiyun {
65*4882a593Smuzhiyun const struct spi_device_id *id = spi_get_device_id(spi);
66*4882a593Smuzhiyun struct regmap *regmap;
67*4882a593Smuzhiyun unsigned int val;
68*4882a593Smuzhiyun int ret;
69*4882a593Smuzhiyun
70*4882a593Smuzhiyun regmap = devm_regmap_init(&spi->dev, &bma400_regmap_bus,
71*4882a593Smuzhiyun &spi->dev, &bma400_regmap_config);
72*4882a593Smuzhiyun if (IS_ERR(regmap)) {
73*4882a593Smuzhiyun dev_err(&spi->dev, "failed to create regmap\n");
74*4882a593Smuzhiyun return PTR_ERR(regmap);
75*4882a593Smuzhiyun }
76*4882a593Smuzhiyun
77*4882a593Smuzhiyun /*
78*4882a593Smuzhiyun * Per the bma400 datasheet, the first SPI read may
79*4882a593Smuzhiyun * return garbage. As the datasheet recommends, the
80*4882a593Smuzhiyun * chip ID register will be read here and checked
81*4882a593Smuzhiyun * again in the following probe.
82*4882a593Smuzhiyun */
83*4882a593Smuzhiyun ret = regmap_read(regmap, BMA400_CHIP_ID_REG, &val);
84*4882a593Smuzhiyun if (ret)
85*4882a593Smuzhiyun dev_err(&spi->dev, "Failed to read chip id register\n");
86*4882a593Smuzhiyun
87*4882a593Smuzhiyun return bma400_probe(&spi->dev, regmap, id->name);
88*4882a593Smuzhiyun }
89*4882a593Smuzhiyun
bma400_spi_remove(struct spi_device * spi)90*4882a593Smuzhiyun static int bma400_spi_remove(struct spi_device *spi)
91*4882a593Smuzhiyun {
92*4882a593Smuzhiyun return bma400_remove(&spi->dev);
93*4882a593Smuzhiyun }
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun static const struct spi_device_id bma400_spi_ids[] = {
96*4882a593Smuzhiyun { "bma400", 0 },
97*4882a593Smuzhiyun { }
98*4882a593Smuzhiyun };
99*4882a593Smuzhiyun MODULE_DEVICE_TABLE(spi, bma400_spi_ids);
100*4882a593Smuzhiyun
101*4882a593Smuzhiyun static const struct of_device_id bma400_of_spi_match[] = {
102*4882a593Smuzhiyun { .compatible = "bosch,bma400" },
103*4882a593Smuzhiyun { }
104*4882a593Smuzhiyun };
105*4882a593Smuzhiyun MODULE_DEVICE_TABLE(of, bma400_of_spi_match);
106*4882a593Smuzhiyun
107*4882a593Smuzhiyun static struct spi_driver bma400_spi_driver = {
108*4882a593Smuzhiyun .driver = {
109*4882a593Smuzhiyun .name = "bma400",
110*4882a593Smuzhiyun .of_match_table = bma400_of_spi_match,
111*4882a593Smuzhiyun },
112*4882a593Smuzhiyun .probe = bma400_spi_probe,
113*4882a593Smuzhiyun .remove = bma400_spi_remove,
114*4882a593Smuzhiyun .id_table = bma400_spi_ids,
115*4882a593Smuzhiyun };
116*4882a593Smuzhiyun
117*4882a593Smuzhiyun module_spi_driver(bma400_spi_driver);
118*4882a593Smuzhiyun MODULE_AUTHOR("Dan Robertson <dan@dlrobertson.com>");
119*4882a593Smuzhiyun MODULE_DESCRIPTION("Bosch BMA400 triaxial acceleration sensor (SPI)");
120*4882a593Smuzhiyun MODULE_LICENSE("GPL");
121