1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * BME680 - SPI Driver
4 *
5 * Copyright (C) 2018 Himanshu Jha <himanshujha199640@gmail.com>
6 */
7 #include <linux/module.h>
8 #include <linux/regmap.h>
9 #include <linux/spi/spi.h>
10
11 #include "bme680.h"
12
13 struct bme680_spi_bus_context {
14 struct spi_device *spi;
15 u8 current_page;
16 };
17
18 /*
19 * In SPI mode there are only 7 address bits, a "page" register determines
20 * which part of the 8-bit range is active. This function looks at the address
21 * and writes the page selection bit if needed
22 */
bme680_regmap_spi_select_page(struct bme680_spi_bus_context * ctx,u8 reg)23 static int bme680_regmap_spi_select_page(
24 struct bme680_spi_bus_context *ctx, u8 reg)
25 {
26 struct spi_device *spi = ctx->spi;
27 int ret;
28 u8 buf[2];
29 u8 page = (reg & 0x80) ? 0 : 1; /* Page "1" is low range */
30
31 if (page == ctx->current_page)
32 return 0;
33
34 /*
35 * Data sheet claims we're only allowed to change bit 4, so we must do
36 * a read-modify-write on each and every page select
37 */
38 buf[0] = BME680_REG_STATUS;
39 ret = spi_write_then_read(spi, buf, 1, buf + 1, 1);
40 if (ret < 0) {
41 dev_err(&spi->dev, "failed to set page %u\n", page);
42 return ret;
43 }
44
45 buf[0] = BME680_REG_STATUS;
46 if (page)
47 buf[1] |= BME680_SPI_MEM_PAGE_BIT;
48 else
49 buf[1] &= ~BME680_SPI_MEM_PAGE_BIT;
50
51 ret = spi_write(spi, buf, 2);
52 if (ret < 0) {
53 dev_err(&spi->dev, "failed to set page %u\n", page);
54 return ret;
55 }
56
57 ctx->current_page = page;
58
59 return 0;
60 }
61
bme680_regmap_spi_write(void * context,const void * data,size_t count)62 static int bme680_regmap_spi_write(void *context, const void *data,
63 size_t count)
64 {
65 struct bme680_spi_bus_context *ctx = context;
66 struct spi_device *spi = ctx->spi;
67 int ret;
68 u8 buf[2];
69
70 memcpy(buf, data, 2);
71
72 ret = bme680_regmap_spi_select_page(ctx, buf[0]);
73 if (ret)
74 return ret;
75
76 /*
77 * The SPI register address (= full register address without bit 7)
78 * and the write command (bit7 = RW = '0')
79 */
80 buf[0] &= ~0x80;
81
82 return spi_write(spi, buf, 2);
83 }
84
bme680_regmap_spi_read(void * context,const void * reg,size_t reg_size,void * val,size_t val_size)85 static int bme680_regmap_spi_read(void *context, const void *reg,
86 size_t reg_size, void *val, size_t val_size)
87 {
88 struct bme680_spi_bus_context *ctx = context;
89 struct spi_device *spi = ctx->spi;
90 int ret;
91 u8 addr = *(const u8 *)reg;
92
93 ret = bme680_regmap_spi_select_page(ctx, addr);
94 if (ret)
95 return ret;
96
97 addr |= 0x80; /* bit7 = RW = '1' */
98
99 return spi_write_then_read(spi, &addr, 1, val, val_size);
100 }
101
102 static const struct regmap_bus bme680_regmap_bus = {
103 .write = bme680_regmap_spi_write,
104 .read = bme680_regmap_spi_read,
105 .reg_format_endian_default = REGMAP_ENDIAN_BIG,
106 .val_format_endian_default = REGMAP_ENDIAN_BIG,
107 };
108
bme680_spi_probe(struct spi_device * spi)109 static int bme680_spi_probe(struct spi_device *spi)
110 {
111 const struct spi_device_id *id = spi_get_device_id(spi);
112 struct bme680_spi_bus_context *bus_context;
113 struct regmap *regmap;
114
115 bus_context = devm_kzalloc(&spi->dev, sizeof(*bus_context), GFP_KERNEL);
116 if (!bus_context)
117 return -ENOMEM;
118
119 bus_context->spi = spi;
120 bus_context->current_page = 0xff; /* Undefined on warm boot */
121
122 regmap = devm_regmap_init(&spi->dev, &bme680_regmap_bus,
123 bus_context, &bme680_regmap_config);
124 if (IS_ERR(regmap))
125 return dev_err_probe(&spi->dev, PTR_ERR(regmap),
126 "Failed to register spi regmap\n");
127
128 return bme680_core_probe(&spi->dev, regmap, id->name);
129 }
130
131 static const struct spi_device_id bme680_spi_id[] = {
132 { .name = "bme680" },
133 { }
134 };
135 MODULE_DEVICE_TABLE(spi, bme680_spi_id);
136
137 static const struct of_device_id bme680_of_spi_match[] = {
138 { .compatible = "bosch,bme680", },
139 { }
140 };
141 MODULE_DEVICE_TABLE(of, bme680_of_spi_match);
142
143 static struct spi_driver bme680_spi_driver = {
144 .driver = {
145 .name = "bme680_spi",
146 .of_match_table = bme680_of_spi_match,
147 .pm = pm_ptr(&bme680_dev_pm_ops),
148 },
149 .probe = bme680_spi_probe,
150 .id_table = bme680_spi_id,
151 };
152 module_spi_driver(bme680_spi_driver);
153
154 MODULE_AUTHOR("Himanshu Jha <himanshujha199640@gmail.com>");
155 MODULE_DESCRIPTION("Bosch BME680 SPI driver");
156 MODULE_LICENSE("GPL v2");
157 MODULE_IMPORT_NS("IIO_BME680");
158