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139 lines
3.2 KiB
139 lines
3.2 KiB
// 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 <[email protected]> |
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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 = &scd30_pm_ops, |
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}, |
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.probe_new = 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 <[email protected]>"); |
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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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