forked from Minki/linux
d4553d6ec1
Add serial interface driver for the SCD30 sensor. Signed-off-by: Tomasz Duszynski <tomasz.duszynski@octakon.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
264 lines
6.9 KiB
C
264 lines
6.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Sensirion SCD30 carbon dioxide sensor serial 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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#include <linux/crc16.h>
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#include <linux/device.h>
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#include <linux/errno.h>
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#include <linux/iio/iio.h>
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#include <linux/jiffies.h>
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#include <linux/mod_devicetable.h>
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#include <linux/module.h>
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#include <linux/property.h>
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#include <linux/serdev.h>
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#include <linux/string.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_SERDEV_ADDR 0x61
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#define SCD30_SERDEV_WRITE 0x06
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#define SCD30_SERDEV_READ 0x03
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#define SCD30_SERDEV_MAX_BUF_SIZE 17
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#define SCD30_SERDEV_RX_HEADER_SIZE 3
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#define SCD30_SERDEV_CRC_SIZE 2
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#define SCD30_SERDEV_TIMEOUT msecs_to_jiffies(200)
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struct scd30_serdev_priv {
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struct completion meas_ready;
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char *buf;
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int num_expected;
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int num;
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};
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static u16 scd30_serdev_cmd_lookup_tbl[] = {
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[CMD_START_MEAS] = 0x0036,
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[CMD_STOP_MEAS] = 0x0037,
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[CMD_MEAS_INTERVAL] = 0x0025,
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[CMD_MEAS_READY] = 0x0027,
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[CMD_READ_MEAS] = 0x0028,
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[CMD_ASC] = 0x003a,
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[CMD_FRC] = 0x0039,
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[CMD_TEMP_OFFSET] = 0x003b,
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[CMD_FW_VERSION] = 0x0020,
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[CMD_RESET] = 0x0034,
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};
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static u16 scd30_serdev_calc_crc(const char *buf, int size)
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{
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return crc16(0xffff, buf, size);
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}
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static int scd30_serdev_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 serdev_device *serdev = to_serdev_device(state->dev);
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struct scd30_serdev_priv *priv = state->priv;
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int ret;
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priv->buf = rxbuf;
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priv->num_expected = rxsize;
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priv->num = 0;
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ret = serdev_device_write(serdev, txbuf, txsize, SCD30_SERDEV_TIMEOUT);
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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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ret = wait_for_completion_interruptible_timeout(&priv->meas_ready, SCD30_SERDEV_TIMEOUT);
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if (ret < 0)
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return ret;
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if (!ret)
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return -ETIMEDOUT;
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return 0;
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}
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static int scd30_serdev_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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/*
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* Communication over serial line is based on modbus protocol (or rather
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* its variation called modbus over serial to be precise). Upon
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* receiving a request device should reply with response.
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*
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* Frame below represents a request message. Each field takes
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* exactly one byte.
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*
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* +------+------+-----+-----+-------+-------+-----+-----+
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* | dev | op | reg | reg | byte1 | byte0 | crc | crc |
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* | addr | code | msb | lsb | | | lsb | msb |
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* +------+------+-----+-----+-------+-------+-----+-----+
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*
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* The message device replies with depends on the 'op code' field from
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* the request. In case it was set to SCD30_SERDEV_WRITE sensor should
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* reply with unchanged request. Otherwise 'op code' was set to
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* SCD30_SERDEV_READ and response looks like the one below. As with
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* request, each field takes one byte.
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*
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* +------+------+--------+-------+-----+-------+-----+-----+
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* | dev | op | num of | byte0 | ... | byteN | crc | crc |
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* | addr | code | bytes | | | | lsb | msb |
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* +------+------+--------+-------+-----+-------+-----+-----+
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*/
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char txbuf[SCD30_SERDEV_MAX_BUF_SIZE] = { SCD30_SERDEV_ADDR },
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rxbuf[SCD30_SERDEV_MAX_BUF_SIZE];
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int ret, rxsize, txsize = 2;
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char *rsp = response;
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u16 crc;
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put_unaligned_be16(scd30_serdev_cmd_lookup_tbl[cmd], txbuf + txsize);
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txsize += 2;
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if (rsp) {
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txbuf[1] = SCD30_SERDEV_READ;
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if (cmd == CMD_READ_MEAS)
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/* number of u16 words to read */
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put_unaligned_be16(size / 2, txbuf + txsize);
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else
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put_unaligned_be16(0x0001, txbuf + txsize);
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txsize += 2;
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crc = scd30_serdev_calc_crc(txbuf, txsize);
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put_unaligned_le16(crc, txbuf + txsize);
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txsize += 2;
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rxsize = SCD30_SERDEV_RX_HEADER_SIZE + size + SCD30_SERDEV_CRC_SIZE;
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} else {
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if ((cmd == CMD_STOP_MEAS) || (cmd == CMD_RESET))
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arg = 0x0001;
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txbuf[1] = SCD30_SERDEV_WRITE;
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put_unaligned_be16(arg, txbuf + txsize);
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txsize += 2;
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crc = scd30_serdev_calc_crc(txbuf, txsize);
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put_unaligned_le16(crc, txbuf + txsize);
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txsize += 2;
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rxsize = txsize;
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}
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ret = scd30_serdev_xfer(state, txbuf, txsize, rxbuf, rxsize);
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if (ret)
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return ret;
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switch (txbuf[1]) {
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case SCD30_SERDEV_WRITE:
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if (memcmp(txbuf, rxbuf, txsize)) {
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dev_err(state->dev, "wrong message received\n");
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return -EIO;
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}
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break;
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case SCD30_SERDEV_READ:
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if (rxbuf[2] != (rxsize - SCD30_SERDEV_RX_HEADER_SIZE - SCD30_SERDEV_CRC_SIZE)) {
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dev_err(state->dev, "received data size does not match header\n");
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return -EIO;
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}
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rxsize -= SCD30_SERDEV_CRC_SIZE;
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crc = get_unaligned_le16(rxbuf + rxsize);
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if (crc != scd30_serdev_calc_crc(rxbuf, rxsize)) {
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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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rxsize -= SCD30_SERDEV_RX_HEADER_SIZE;
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memcpy(rsp, rxbuf + SCD30_SERDEV_RX_HEADER_SIZE, rxsize);
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break;
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default:
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dev_err(state->dev, "received unknown op code\n");
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return -EIO;
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}
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return 0;
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}
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static int scd30_serdev_receive_buf(struct serdev_device *serdev,
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const unsigned char *buf, size_t size)
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{
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struct iio_dev *indio_dev = dev_get_drvdata(&serdev->dev);
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struct scd30_serdev_priv *priv;
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struct scd30_state *state;
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int num;
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if (!indio_dev)
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return 0;
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state = iio_priv(indio_dev);
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priv = state->priv;
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/* just in case sensor puts some unexpected bytes on the bus */
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if (!priv->buf)
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return 0;
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if (priv->num + size >= priv->num_expected)
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num = priv->num_expected - priv->num;
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else
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num = size;
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memcpy(priv->buf + priv->num, buf, num);
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priv->num += num;
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if (priv->num == priv->num_expected) {
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priv->buf = NULL;
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complete(&priv->meas_ready);
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}
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return num;
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}
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static const struct serdev_device_ops scd30_serdev_ops = {
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.receive_buf = scd30_serdev_receive_buf,
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.write_wakeup = serdev_device_write_wakeup,
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};
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static int scd30_serdev_probe(struct serdev_device *serdev)
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{
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struct device *dev = &serdev->dev;
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struct scd30_serdev_priv *priv;
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int irq, ret;
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priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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init_completion(&priv->meas_ready);
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serdev_device_set_client_ops(serdev, &scd30_serdev_ops);
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ret = devm_serdev_device_open(dev, serdev);
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if (ret)
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return ret;
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serdev_device_set_baudrate(serdev, 19200);
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serdev_device_set_flow_control(serdev, false);
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ret = serdev_device_set_parity(serdev, SERDEV_PARITY_NONE);
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if (ret)
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return ret;
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irq = fwnode_irq_get(dev_fwnode(dev), 0);
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return scd30_probe(dev, irq, KBUILD_MODNAME, priv, scd30_serdev_command);
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}
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static const struct of_device_id scd30_serdev_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_serdev_of_match);
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static struct serdev_device_driver scd30_serdev_driver = {
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.driver = {
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.name = KBUILD_MODNAME,
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.of_match_table = scd30_serdev_of_match,
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.pm = &scd30_pm_ops,
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},
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.probe = scd30_serdev_probe,
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};
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module_serdev_device_driver(scd30_serdev_driver);
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MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
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MODULE_DESCRIPTION("Sensirion SCD30 carbon dioxide sensor serial driver");
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MODULE_LICENSE("GPL v2");
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