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