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/acpi.h>
8 #include <linux/module.h>
9 #include <linux/regmap.h>
10 #include <linux/spi/spi.h>
11 
12 #include "bme680.h"
13 
14 static int bme680_regmap_spi_write(void *context, const void *data,
15 				   size_t count)
16 {
17 	struct spi_device *spi = context;
18 	u8 buf[2];
19 
20 	memcpy(buf, data, 2);
21 	/*
22 	 * The SPI register address (= full register address without bit 7)
23 	 * and the write command (bit7 = RW = '0')
24 	 */
25 	buf[0] &= ~0x80;
26 
27 	return spi_write_then_read(spi, buf, 2, NULL, 0);
28 }
29 
30 static int bme680_regmap_spi_read(void *context, const void *reg,
31 				  size_t reg_size, void *val, size_t val_size)
32 {
33 	struct spi_device *spi = context;
34 
35 	return spi_write_then_read(spi, reg, reg_size, val, val_size);
36 }
37 
38 static struct regmap_bus bme680_regmap_bus = {
39 	.write = bme680_regmap_spi_write,
40 	.read = bme680_regmap_spi_read,
41 	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
42 	.val_format_endian_default = REGMAP_ENDIAN_BIG,
43 };
44 
45 static int bme680_spi_probe(struct spi_device *spi)
46 {
47 	const struct spi_device_id *id = spi_get_device_id(spi);
48 	struct regmap *regmap;
49 	unsigned int val;
50 	int ret;
51 
52 	spi->bits_per_word = 8;
53 	ret = spi_setup(spi);
54 	if (ret < 0) {
55 		dev_err(&spi->dev, "spi_setup failed!\n");
56 		return ret;
57 	}
58 
59 	regmap = devm_regmap_init(&spi->dev, &bme680_regmap_bus,
60 				  &spi->dev, &bme680_regmap_config);
61 	if (IS_ERR(regmap)) {
62 		dev_err(&spi->dev, "Failed to register spi regmap %d\n",
63 				(int)PTR_ERR(regmap));
64 		return PTR_ERR(regmap);
65 	}
66 
67 	ret = regmap_write(regmap, BME680_REG_SOFT_RESET_SPI,
68 			   BME680_CMD_SOFTRESET);
69 	if (ret < 0) {
70 		dev_err(&spi->dev, "Failed to reset chip\n");
71 		return ret;
72 	}
73 
74 	/* after power-on reset, Page 0(0x80-0xFF) of spi_mem_page is active */
75 	ret = regmap_read(regmap, BME680_REG_CHIP_SPI_ID, &val);
76 	if (ret < 0) {
77 		dev_err(&spi->dev, "Error reading SPI chip ID\n");
78 		return ret;
79 	}
80 
81 	if (val != BME680_CHIP_ID_VAL) {
82 		dev_err(&spi->dev, "Wrong chip ID, got %x expected %x\n",
83 				val, BME680_CHIP_ID_VAL);
84 		return -ENODEV;
85 	}
86 	/*
87 	 * select Page 1 of spi_mem_page to enable access to
88 	 * to registers from address 0x00 to 0x7F.
89 	 */
90 	ret = regmap_write_bits(regmap, BME680_REG_STATUS,
91 				BME680_SPI_MEM_PAGE_BIT,
92 				BME680_SPI_MEM_PAGE_1_VAL);
93 	if (ret < 0) {
94 		dev_err(&spi->dev, "failed to set page 1 of spi_mem_page\n");
95 		return ret;
96 	}
97 
98 	return bme680_core_probe(&spi->dev, regmap, id->name);
99 }
100 
101 static const struct spi_device_id bme680_spi_id[] = {
102 	{"bme680", 0},
103 	{},
104 };
105 MODULE_DEVICE_TABLE(spi, bme680_spi_id);
106 
107 static const struct acpi_device_id bme680_acpi_match[] = {
108 	{"BME0680", 0},
109 	{},
110 };
111 MODULE_DEVICE_TABLE(acpi, bme680_acpi_match);
112 
113 static struct spi_driver bme680_spi_driver = {
114 	.driver = {
115 		.name			= "bme680_spi",
116 		.acpi_match_table	= ACPI_PTR(bme680_acpi_match),
117 	},
118 	.probe = bme680_spi_probe,
119 	.id_table = bme680_spi_id,
120 };
121 module_spi_driver(bme680_spi_driver);
122 
123 MODULE_AUTHOR("Himanshu Jha <himanshujha199640@gmail.com>");
124 MODULE_DESCRIPTION("Bosch BME680 SPI driver");
125 MODULE_LICENSE("GPL v2");
126