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/of.h> 10 #include <linux/regmap.h> 11 #include <linux/spi/spi.h> 12 13 #include "bme680.h" 14 15 struct bme680_spi_bus_context { 16 struct spi_device *spi; 17 u8 current_page; 18 }; 19 20 /* 21 * In SPI mode there are only 7 address bits, a "page" register determines 22 * which part of the 8-bit range is active. This function looks at the address 23 * and writes the page selection bit if needed 24 */ 25 static int bme680_regmap_spi_select_page( 26 struct bme680_spi_bus_context *ctx, u8 reg) 27 { 28 struct spi_device *spi = ctx->spi; 29 int ret; 30 u8 buf[2]; 31 u8 page = (reg & 0x80) ? 0 : 1; /* Page "1" is low range */ 32 33 if (page == ctx->current_page) 34 return 0; 35 36 /* 37 * Data sheet claims we're only allowed to change bit 4, so we must do 38 * a read-modify-write on each and every page select 39 */ 40 buf[0] = BME680_REG_STATUS; 41 ret = spi_write_then_read(spi, buf, 1, buf + 1, 1); 42 if (ret < 0) { 43 dev_err(&spi->dev, "failed to set page %u\n", page); 44 return ret; 45 } 46 47 buf[0] = BME680_REG_STATUS; 48 if (page) 49 buf[1] |= BME680_SPI_MEM_PAGE_BIT; 50 else 51 buf[1] &= ~BME680_SPI_MEM_PAGE_BIT; 52 53 ret = spi_write(spi, buf, 2); 54 if (ret < 0) { 55 dev_err(&spi->dev, "failed to set page %u\n", page); 56 return ret; 57 } 58 59 ctx->current_page = page; 60 61 return 0; 62 } 63 64 static int bme680_regmap_spi_write(void *context, const void *data, 65 size_t count) 66 { 67 struct bme680_spi_bus_context *ctx = context; 68 struct spi_device *spi = ctx->spi; 69 int ret; 70 u8 buf[2]; 71 72 memcpy(buf, data, 2); 73 74 ret = bme680_regmap_spi_select_page(ctx, buf[0]); 75 if (ret) 76 return ret; 77 78 /* 79 * The SPI register address (= full register address without bit 7) 80 * and the write command (bit7 = RW = '0') 81 */ 82 buf[0] &= ~0x80; 83 84 return spi_write(spi, buf, 2); 85 } 86 87 static int bme680_regmap_spi_read(void *context, const void *reg, 88 size_t reg_size, void *val, size_t val_size) 89 { 90 struct bme680_spi_bus_context *ctx = context; 91 struct spi_device *spi = ctx->spi; 92 int ret; 93 u8 addr = *(const u8 *)reg; 94 95 ret = bme680_regmap_spi_select_page(ctx, addr); 96 if (ret) 97 return ret; 98 99 addr |= 0x80; /* bit7 = RW = '1' */ 100 101 return spi_write_then_read(spi, &addr, 1, val, val_size); 102 } 103 104 static struct regmap_bus bme680_regmap_bus = { 105 .write = bme680_regmap_spi_write, 106 .read = bme680_regmap_spi_read, 107 .reg_format_endian_default = REGMAP_ENDIAN_BIG, 108 .val_format_endian_default = REGMAP_ENDIAN_BIG, 109 }; 110 111 static int bme680_spi_probe(struct spi_device *spi) 112 { 113 const struct spi_device_id *id = spi_get_device_id(spi); 114 struct bme680_spi_bus_context *bus_context; 115 struct regmap *regmap; 116 int ret; 117 118 spi->bits_per_word = 8; 119 ret = spi_setup(spi); 120 if (ret < 0) { 121 dev_err(&spi->dev, "spi_setup failed!\n"); 122 return ret; 123 } 124 125 bus_context = devm_kzalloc(&spi->dev, sizeof(*bus_context), GFP_KERNEL); 126 if (!bus_context) 127 return -ENOMEM; 128 129 bus_context->spi = spi; 130 bus_context->current_page = 0xff; /* Undefined on warm boot */ 131 132 regmap = devm_regmap_init(&spi->dev, &bme680_regmap_bus, 133 bus_context, &bme680_regmap_config); 134 if (IS_ERR(regmap)) { 135 dev_err(&spi->dev, "Failed to register spi regmap %d\n", 136 (int)PTR_ERR(regmap)); 137 return PTR_ERR(regmap); 138 } 139 140 return bme680_core_probe(&spi->dev, regmap, id->name); 141 } 142 143 static const struct spi_device_id bme680_spi_id[] = { 144 {"bme680", 0}, 145 {}, 146 }; 147 MODULE_DEVICE_TABLE(spi, bme680_spi_id); 148 149 static const struct acpi_device_id bme680_acpi_match[] = { 150 {"BME0680", 0}, 151 {}, 152 }; 153 MODULE_DEVICE_TABLE(acpi, bme680_acpi_match); 154 155 static const struct of_device_id bme680_of_spi_match[] = { 156 { .compatible = "bosch,bme680", }, 157 {}, 158 }; 159 MODULE_DEVICE_TABLE(of, bme680_of_spi_match); 160 161 static struct spi_driver bme680_spi_driver = { 162 .driver = { 163 .name = "bme680_spi", 164 .acpi_match_table = ACPI_PTR(bme680_acpi_match), 165 .of_match_table = bme680_of_spi_match, 166 }, 167 .probe = bme680_spi_probe, 168 .id_table = bme680_spi_id, 169 }; 170 module_spi_driver(bme680_spi_driver); 171 172 MODULE_AUTHOR("Himanshu Jha <himanshujha199640@gmail.com>"); 173 MODULE_DESCRIPTION("Bosch BME680 SPI driver"); 174 MODULE_LICENSE("GPL v2"); 175