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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 | // 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 = 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); |