diff mbox series

[v3,2/4] iio: chemical: scd30: add I2C interface driver

Message ID 20200602164723.28858-3-tomasz.duszynski@octakon.com (mailing list archive)
State New, archived
Headers show
Series Add support for SCD30 sensor | expand

Commit Message

Tomasz Duszynski June 2, 2020, 4:47 p.m. UTC 
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

Comments

Andy Shevchenko June 2, 2020, 5:14 p.m. UTC | #1 
On Tue, Jun 2, 2020 at 7:49 PM Tomasz Duszynski
<tomasz.duszynski@octakon.com> wrote:
>
> Add I2C interface driver for the SCD30 sensor.

...

> +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,

Keep sorted by value?

> +};

...

> +       ret = i2c_master_send(client, txbuf, txsize);

> +       if (ret != txsize)
> +               return ret < 0 ? ret : -EIO;

Wouldn't be better

  if (ret < 0)
    return ret;
  if (ret != txsize)
    return -EIO;

?

> +       if (!rxbuf)
> +               return 0;
> +
> +       ret = i2c_master_recv(client, rxbuf, rxsize);

> +       if (ret != rxsize)
> +               return ret < 0 ? ret : -EIO;

Ditto.

...

> +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;

i -> offset ?

> +       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;

buf[offset++] = crc; ?

> +               /* 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];

+ 0 (for the sake of consistency?

> +               *rsp++ = buf[i + 1];
> +       }
> +
> +       return 0;
> +}

...

> +static struct i2c_driver scd30_i2c_driver = {
> +       .driver = {

> +               .name = KBUILD_MODNAME,

Better to hard code.

> +               .of_match_table = scd30_i2c_of_match,
> +               .pm = &scd30_pm_ops,
> +       },
> +       .probe_new = scd30_i2c_probe,
> +};
Tomasz Duszynski June 2, 2020, 5:48 p.m. UTC | #2 
Hello Andy,

On Tue, Jun 02, 2020 at 08:14:13PM +0300, Andy Shevchenko wrote:
> On Tue, Jun 2, 2020 at 7:49 PM Tomasz Duszynski
> <tomasz.duszynski@octakon.com> wrote:
> >
> > Add I2C interface driver for the SCD30 sensor.
>
> ...
>
> > +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,
>
> Keep sorted by value?
>

I'd rather leave it as is simply because order here matches order in
sensor datasheet.

> > +};
>
> ...
>
> > +       ret = i2c_master_send(client, txbuf, txsize);
>
> > +       if (ret != txsize)
> > +               return ret < 0 ? ret : -EIO;
>
> Wouldn't be better
>
>   if (ret < 0)
>     return ret;
>   if (ret != txsize)
>     return -EIO;
>
> ?
>

Hmm, okay. Perhaps slightly easier to read.

> > +       if (!rxbuf)
> > +               return 0;
> > +
> > +       ret = i2c_master_recv(client, rxbuf, rxsize);
>
> > +       if (ret != rxsize)
> > +               return ret < 0 ? ret : -EIO;
>
> Ditto.
>
> ...
>
> > +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;
>
> i -> offset ?
>

'i' is shorter and I am lazy :).

> > +       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;
>
> buf[offset++] = crc; ?
>

I'd rather stick to what I have now. It looks more consistent.

> > +               /* 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];
>
> + 0 (for the sake of consistency?
>

Adding 0 is a little bit odd.

> > +               *rsp++ = buf[i + 1];
> > +       }
> > +
> > +       return 0;
> > +}
>
> ...
>
> > +static struct i2c_driver scd30_i2c_driver = {
> > +       .driver = {
>
> > +               .name = KBUILD_MODNAME,
>
> Better to hard code.
>

I seriously doubt anyone will ever want to change module name. What for?

> > +               .of_match_table = scd30_i2c_of_match,
> > +               .pm = &scd30_pm_ops,
> > +       },
> > +       .probe_new = scd30_i2c_probe,
> > +};
>
> --
> With Best Regards,
> Andy Shevchenko
diff mbox series

Patch

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");