141 lines
3.2 KiB
C
141 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Sensirion SCD30 carbon dioxide sensor i2c driver
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*
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* Copyright (c) 2020 Tomasz Duszynski <tomasz.duszynski@octakon.com>
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*
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* I2C slave address: 0x61
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*/
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#include <linux/crc8.h>
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#include <linux/device.h>
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#include <linux/errno.h>
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#include <linux/i2c.h>
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#include <linux/mod_devicetable.h>
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#include <linux/module.h>
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#include <linux/types.h>
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#include <asm/unaligned.h>
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#include "scd30.h"
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#define SCD30_I2C_MAX_BUF_SIZE 18
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#define SCD30_I2C_CRC8_POLYNOMIAL 0x31
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static u16 scd30_i2c_cmd_lookup_tbl[] = {
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[CMD_START_MEAS] = 0x0010,
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[CMD_STOP_MEAS] = 0x0104,
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[CMD_MEAS_INTERVAL] = 0x4600,
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[CMD_MEAS_READY] = 0x0202,
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[CMD_READ_MEAS] = 0x0300,
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[CMD_ASC] = 0x5306,
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[CMD_FRC] = 0x5204,
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[CMD_TEMP_OFFSET] = 0x5403,
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[CMD_FW_VERSION] = 0xd100,
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[CMD_RESET] = 0xd304,
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};
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DECLARE_CRC8_TABLE(scd30_i2c_crc8_tbl);
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static int scd30_i2c_xfer(struct scd30_state *state, char *txbuf, int txsize,
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char *rxbuf, int rxsize)
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{
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struct i2c_client *client = to_i2c_client(state->dev);
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int ret;
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/*
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* repeated start is not supported hence instead of sending two i2c
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* messages in a row we send one by one
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*/
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ret = i2c_master_send(client, txbuf, txsize);
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if (ret < 0)
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return ret;
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if (ret != txsize)
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return -EIO;
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if (!rxbuf)
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return 0;
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ret = i2c_master_recv(client, rxbuf, rxsize);
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if (ret < 0)
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return ret;
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if (ret != rxsize)
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return -EIO;
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return 0;
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}
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static int scd30_i2c_command(struct scd30_state *state, enum scd30_cmd cmd, u16 arg,
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void *response, int size)
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{
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char buf[SCD30_I2C_MAX_BUF_SIZE];
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char *rsp = response;
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int i, ret;
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char crc;
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put_unaligned_be16(scd30_i2c_cmd_lookup_tbl[cmd], buf);
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i = 2;
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if (rsp) {
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/* each two bytes are followed by a crc8 */
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size += size / 2;
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} else {
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put_unaligned_be16(arg, buf + i);
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crc = crc8(scd30_i2c_crc8_tbl, buf + i, 2, CRC8_INIT_VALUE);
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i += 2;
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buf[i] = crc;
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i += 1;
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/* commands below don't take an argument */
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if ((cmd == CMD_STOP_MEAS) || (cmd == CMD_RESET))
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i -= 3;
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}
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ret = scd30_i2c_xfer(state, buf, i, buf, size);
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if (ret)
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return ret;
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/* validate received data and strip off crc bytes */
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for (i = 0; i < size; i += 3) {
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crc = crc8(scd30_i2c_crc8_tbl, buf + i, 2, CRC8_INIT_VALUE);
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if (crc != buf[i + 2]) {
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dev_err(state->dev, "data integrity check failed\n");
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return -EIO;
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}
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*rsp++ = buf[i];
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*rsp++ = buf[i + 1];
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}
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return 0;
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}
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static int scd30_i2c_probe(struct i2c_client *client)
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{
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
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return -EOPNOTSUPP;
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crc8_populate_msb(scd30_i2c_crc8_tbl, SCD30_I2C_CRC8_POLYNOMIAL);
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return scd30_probe(&client->dev, client->irq, client->name, NULL, scd30_i2c_command);
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}
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static const struct of_device_id scd30_i2c_of_match[] = {
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{ .compatible = "sensirion,scd30" },
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{ }
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};
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MODULE_DEVICE_TABLE(of, scd30_i2c_of_match);
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static struct i2c_driver scd30_i2c_driver = {
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.driver = {
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.name = KBUILD_MODNAME,
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.of_match_table = scd30_i2c_of_match,
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.pm = pm_sleep_ptr(&scd30_pm_ops),
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},
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.probe = scd30_i2c_probe,
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};
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module_i2c_driver(scd30_i2c_driver);
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MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
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MODULE_DESCRIPTION("Sensirion SCD30 carbon dioxide sensor i2c driver");
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MODULE_LICENSE("GPL v2");
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MODULE_IMPORT_NS(IIO_SCD30);
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