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1// SPDX-License-Identifier: GPL-2.02/*3 * Sensirion SCD30 carbon dioxide sensor i2c driver4 *5 * Copyright (c) 2020 Tomasz Duszynski <tomasz.duszynski@octakon.com>6 *7 * I2C slave address: 0x618 */9#include <linux/crc8.h>10#include <linux/device.h>11#include <linux/errno.h>12#include <linux/i2c.h>13#include <linux/mod_devicetable.h>14#include <linux/module.h>15#include <linux/types.h>16#include <linux/unaligned.h>17 18#include "scd30.h"19 20#define SCD30_I2C_MAX_BUF_SIZE 1821#define SCD30_I2C_CRC8_POLYNOMIAL 0x3122 23static u16 scd30_i2c_cmd_lookup_tbl[] = {24 [CMD_START_MEAS] = 0x0010,25 [CMD_STOP_MEAS] = 0x0104,26 [CMD_MEAS_INTERVAL] = 0x4600,27 [CMD_MEAS_READY] = 0x0202,28 [CMD_READ_MEAS] = 0x0300,29 [CMD_ASC] = 0x5306,30 [CMD_FRC] = 0x5204,31 [CMD_TEMP_OFFSET] = 0x5403,32 [CMD_FW_VERSION] = 0xd100,33 [CMD_RESET] = 0xd304,34};35 36DECLARE_CRC8_TABLE(scd30_i2c_crc8_tbl);37 38static int scd30_i2c_xfer(struct scd30_state *state, char *txbuf, int txsize,39 char *rxbuf, int rxsize)40{41 struct i2c_client *client = to_i2c_client(state->dev);42 int ret;43 44 /*45 * repeated start is not supported hence instead of sending two i2c46 * messages in a row we send one by one47 */48 ret = i2c_master_send(client, txbuf, txsize);49 if (ret < 0)50 return ret;51 if (ret != txsize)52 return -EIO;53 54 if (!rxbuf)55 return 0;56 57 ret = i2c_master_recv(client, rxbuf, rxsize);58 if (ret < 0)59 return ret;60 if (ret != rxsize)61 return -EIO;62 63 return 0;64}65 66static int scd30_i2c_command(struct scd30_state *state, enum scd30_cmd cmd, u16 arg,67 void *response, int size)68{69 char buf[SCD30_I2C_MAX_BUF_SIZE];70 char *rsp = response;71 int i, ret;72 char crc;73 74 put_unaligned_be16(scd30_i2c_cmd_lookup_tbl[cmd], buf);75 i = 2;76 77 if (rsp) {78 /* each two bytes are followed by a crc8 */79 size += size / 2;80 } else {81 put_unaligned_be16(arg, buf + i);82 crc = crc8(scd30_i2c_crc8_tbl, buf + i, 2, CRC8_INIT_VALUE);83 i += 2;84 buf[i] = crc;85 i += 1;86 87 /* commands below don't take an argument */88 if ((cmd == CMD_STOP_MEAS) || (cmd == CMD_RESET))89 i -= 3;90 }91 92 ret = scd30_i2c_xfer(state, buf, i, buf, size);93 if (ret)94 return ret;95 96 /* validate received data and strip off crc bytes */97 for (i = 0; i < size; i += 3) {98 crc = crc8(scd30_i2c_crc8_tbl, buf + i, 2, CRC8_INIT_VALUE);99 if (crc != buf[i + 2]) {100 dev_err(state->dev, "data integrity check failed\n");101 return -EIO;102 }103 104 *rsp++ = buf[i];105 *rsp++ = buf[i + 1];106 }107 108 return 0;109}110 111static int scd30_i2c_probe(struct i2c_client *client)112{113 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))114 return -EOPNOTSUPP;115 116 crc8_populate_msb(scd30_i2c_crc8_tbl, SCD30_I2C_CRC8_POLYNOMIAL);117 118 return scd30_probe(&client->dev, client->irq, client->name, NULL, scd30_i2c_command);119}120 121static const struct of_device_id scd30_i2c_of_match[] = {122 { .compatible = "sensirion,scd30" },123 { }124};125MODULE_DEVICE_TABLE(of, scd30_i2c_of_match);126 127static struct i2c_driver scd30_i2c_driver = {128 .driver = {129 .name = KBUILD_MODNAME,130 .of_match_table = scd30_i2c_of_match,131 .pm = pm_sleep_ptr(&scd30_pm_ops),132 },133 .probe = scd30_i2c_probe,134};135module_i2c_driver(scd30_i2c_driver);136 137MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");138MODULE_DESCRIPTION("Sensirion SCD30 carbon dioxide sensor i2c driver");139MODULE_LICENSE("GPL v2");140MODULE_IMPORT_NS(IIO_SCD30);141