diff options
Diffstat (limited to 'drivers/iio/chemical/bme680_spi.c')
| -rw-r--r-- | drivers/iio/chemical/bme680_spi.c | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/drivers/iio/chemical/bme680_spi.c b/drivers/iio/chemical/bme680_spi.c new file mode 100644 index 000000000..4404d42ae --- /dev/null +++ b/drivers/iio/chemical/bme680_spi.c @@ -0,0 +1,166 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * BME680 - SPI Driver + * + * Copyright (C) 2018 Himanshu Jha <himanshujha199640@gmail.com> + */ +#include <linux/mod_devicetable.h> +#include <linux/module.h> +#include <linux/regmap.h> +#include <linux/spi/spi.h> + +#include "bme680.h" + +struct bme680_spi_bus_context { + struct spi_device *spi; + u8 current_page; +}; + +/* + * In SPI mode there are only 7 address bits, a "page" register determines + * which part of the 8-bit range is active. This function looks at the address + * and writes the page selection bit if needed + */ +static int bme680_regmap_spi_select_page( + struct bme680_spi_bus_context *ctx, u8 reg) +{ + struct spi_device *spi = ctx->spi; + int ret; + u8 buf[2]; + u8 page = (reg & 0x80) ? 0 : 1; /* Page "1" is low range */ + + if (page == ctx->current_page) + return 0; + + /* + * Data sheet claims we're only allowed to change bit 4, so we must do + * a read-modify-write on each and every page select + */ + buf[0] = BME680_REG_STATUS; + ret = spi_write_then_read(spi, buf, 1, buf + 1, 1); + if (ret < 0) { + dev_err(&spi->dev, "failed to set page %u\n", page); + return ret; + } + + buf[0] = BME680_REG_STATUS; + if (page) + buf[1] |= BME680_SPI_MEM_PAGE_BIT; + else + buf[1] &= ~BME680_SPI_MEM_PAGE_BIT; + + ret = spi_write(spi, buf, 2); + if (ret < 0) { + dev_err(&spi->dev, "failed to set page %u\n", page); + return ret; + } + + ctx->current_page = page; + + return 0; +} + +static int bme680_regmap_spi_write(void *context, const void *data, + size_t count) +{ + struct bme680_spi_bus_context *ctx = context; + struct spi_device *spi = ctx->spi; + int ret; + u8 buf[2]; + + memcpy(buf, data, 2); + + ret = bme680_regmap_spi_select_page(ctx, buf[0]); + if (ret) + return ret; + + /* + * The SPI register address (= full register address without bit 7) + * and the write command (bit7 = RW = '0') + */ + buf[0] &= ~0x80; + + return spi_write(spi, buf, 2); +} + +static int bme680_regmap_spi_read(void *context, const void *reg, + size_t reg_size, void *val, size_t val_size) +{ + struct bme680_spi_bus_context *ctx = context; + struct spi_device *spi = ctx->spi; + int ret; + u8 addr = *(const u8 *)reg; + + ret = bme680_regmap_spi_select_page(ctx, addr); + if (ret) + return ret; + + addr |= 0x80; /* bit7 = RW = '1' */ + + return spi_write_then_read(spi, &addr, 1, val, val_size); +} + +static struct regmap_bus bme680_regmap_bus = { + .write = bme680_regmap_spi_write, + .read = bme680_regmap_spi_read, + .reg_format_endian_default = REGMAP_ENDIAN_BIG, + .val_format_endian_default = REGMAP_ENDIAN_BIG, +}; + +static int bme680_spi_probe(struct spi_device *spi) +{ + const struct spi_device_id *id = spi_get_device_id(spi); + struct bme680_spi_bus_context *bus_context; + struct regmap *regmap; + int ret; + + spi->bits_per_word = 8; + ret = spi_setup(spi); + if (ret < 0) { + dev_err(&spi->dev, "spi_setup failed!\n"); + return ret; + } + + bus_context = devm_kzalloc(&spi->dev, sizeof(*bus_context), GFP_KERNEL); + if (!bus_context) + return -ENOMEM; + + bus_context->spi = spi; + bus_context->current_page = 0xff; /* Undefined on warm boot */ + + regmap = devm_regmap_init(&spi->dev, &bme680_regmap_bus, + bus_context, &bme680_regmap_config); + if (IS_ERR(regmap)) { + dev_err(&spi->dev, "Failed to register spi regmap %ld\n", PTR_ERR(regmap)); + return PTR_ERR(regmap); + } + + return bme680_core_probe(&spi->dev, regmap, id->name); +} + +static const struct spi_device_id bme680_spi_id[] = { + {"bme680", 0}, + {}, +}; +MODULE_DEVICE_TABLE(spi, bme680_spi_id); + +static const struct of_device_id bme680_of_spi_match[] = { + { .compatible = "bosch,bme680", }, + {}, +}; +MODULE_DEVICE_TABLE(of, bme680_of_spi_match); + +static struct spi_driver bme680_spi_driver = { + .driver = { + .name = "bme680_spi", + .of_match_table = bme680_of_spi_match, + }, + .probe = bme680_spi_probe, + .id_table = bme680_spi_id, +}; +module_spi_driver(bme680_spi_driver); + +MODULE_AUTHOR("Himanshu Jha <himanshujha199640@gmail.com>"); +MODULE_DESCRIPTION("Bosch BME680 SPI driver"); +MODULE_LICENSE("GPL v2"); +MODULE_IMPORT_NS(IIO_BME680); |