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Subject[PATCH v2 2/4] iio: chemical: scd30: add I2C interface driver
Date
Add I2C interface driver for the SCD30 sensor.

Signed-off-by: Tomasz Duszynski <tomasz.duszynski@octakon.com>
---
MAINTAINERS | 1 +
drivers/iio/chemical/Kconfig | 11 +++
drivers/iio/chemical/Makefile | 1 +
drivers/iio/chemical/scd30_i2c.c | 134 +++++++++++++++++++++++++++++++
4 files changed, 147 insertions(+)
create mode 100644 drivers/iio/chemical/scd30_i2c.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 41a509cca6f1..13aed3473b7e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15142,6 +15142,7 @@ M: Tomasz Duszynski <tomasz.duszynski@octakon.com>
S: Maintained
F: drivers/iio/chemical/scd30.h
F: drivers/iio/chemical/scd30_core.c
+F: drivers/iio/chemical/scd30_i2c.c

SENSIRION SPS30 AIR POLLUTION SENSOR DRIVER
M: Tomasz Duszynski <tduszyns@gmail.com>
diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
index 99e852b67e55..970d34888c2e 100644
--- a/drivers/iio/chemical/Kconfig
+++ b/drivers/iio/chemical/Kconfig
@@ -96,6 +96,17 @@ config SCD30_CORE
To compile this driver as a module, choose M here: the module will
be called scd30_core.

+config SCD30_I2C
+ tristate "SCD30 carbon dioxide sensor I2C driver"
+ depends on SCD30_CORE && I2C
+ select CRC8
+ help
+ Say Y here to build support for the Sensirion SCD30 I2C interface
+ driver.
+
+ To compile this driver as a module, choose M here: the module will
+ be called scd30_i2c.
+
config SENSIRION_SGP30
tristate "Sensirion SGPxx gas sensors"
depends on I2C
diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
index c9804b041ecd..0966ca34e34b 100644
--- a/drivers/iio/chemical/Makefile
+++ b/drivers/iio/chemical/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_CCS811) += ccs811.o
obj-$(CONFIG_IAQCORE) += ams-iaq-core.o
obj-$(CONFIG_PMS7003) += pms7003.o
obj-$(CONFIG_SCD30_CORE) += scd30_core.o
+obj-$(CONFIG_SCD30_I2C) += scd30_i2c.o
obj-$(CONFIG_SENSIRION_SGP30) += sgp30.o
obj-$(CONFIG_SPS30) += sps30.o
obj-$(CONFIG_VZ89X) += vz89x.o
diff --git a/drivers/iio/chemical/scd30_i2c.c b/drivers/iio/chemical/scd30_i2c.c
new file mode 100644
index 000000000000..a6b532b83669
--- /dev/null
+++ b/drivers/iio/chemical/scd30_i2c.c
@@ -0,0 +1,134 @@
+// 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 != txsize)
+ return ret < 0 ? ret : -EIO;
+
+ if (!rxbuf)
+ return 0;
+
+ ret = i2c_master_recv(client, rxbuf, rxsize);
+ if (ret != rxsize)
+ return ret < 0 ? ret : -EIO;
+
+ return 0;
+}
+
+static int scd30_i2c_command(struct scd30_state *state, enum scd30_cmd cmd,
+ u16 arg, void *response, int size)
+{
+ char crc, buf[SCD30_I2C_MAX_BUF_SIZE], *rsp = response;
+ int i, ret;
+
+ 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 = &scd30_pm_ops,
+ },
+ .probe_new = 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");
--
2.26.2
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