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263 lines
6.9 KiB
263 lines
6.9 KiB
// 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 <[email protected]> |
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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 = serdev_device_get_drvdata(serdev); |
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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 <[email protected]>"); |
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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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