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