On Sun, May 3, 2020 at 3:17 AM Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
>
> On Tue, 28 Apr 2020 08:41:07 +0300
> Matt Ranostay <matt.ranostay@xxxxxxxxxxxx> wrote:
>
> > Add driver for Atlas EZO line of sensors with initial support for
> > CO2 the sensor. This is effectively ASCII strings proxied over I2C
> > due to these series of sensors being by default UART.
> >
> > Signed-off-by: Matt Ranostay <matt.ranostay@xxxxxxxxxxxx>
>
> A few things inline - including a dive into a bit of the i2c subsystem
> that's been there for a few years, but never used ;)
>
> Jonathan
>
> > ---
> > drivers/iio/chemical/Kconfig | 11 ++
> > drivers/iio/chemical/Makefile | 1 +
> > drivers/iio/chemical/atlas-ezo-sensor.c | 173 ++++++++++++++++++++++++
> > 3 files changed, 185 insertions(+)
> > create mode 100644 drivers/iio/chemical/atlas-ezo-sensor.c
> >
> > diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
> > index a7e65a59bf42..7f21afd73b1c 100644
> > --- a/drivers/iio/chemical/Kconfig
> > +++ b/drivers/iio/chemical/Kconfig
> > @@ -22,6 +22,17 @@ config ATLAS_PH_SENSOR
> > To compile this driver as module, choose M here: the
> > module will be called atlas-ph-sensor.
> >
> > +config ATLAS_EZO_SENSOR
> > + tristate "Atlas Scientific EZO sensors"
> > + depends on I2C
> > + help
> > + Say Y here to build I2C interface support for the following
> > + Atlas Scientific EZO sensors
> > + * CO2 EZO Sensor
> > +
> > + To compile this driver as module, choose M here: the
> > + module will be called atlas-ezo-sensor.
> > +
> > config BME680
> > tristate "Bosch Sensortec BME680 sensor driver"
> > depends on (I2C || SPI)
> > diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
> > index 33d3a595dda9..aba4167db745 100644
> > --- a/drivers/iio/chemical/Makefile
> > +++ b/drivers/iio/chemical/Makefile
> > @@ -5,6 +5,7 @@
> >
> > # When adding new entries keep the list in alphabetical order
> > obj-$(CONFIG_ATLAS_PH_SENSOR) += atlas-sensor.o
> > +obj-$(CONFIG_ATLAS_EZO_SENSOR) += atlas-ezo-sensor.o
> > obj-$(CONFIG_BME680) += bme680_core.o
> > obj-$(CONFIG_BME680_I2C) += bme680_i2c.o
> > obj-$(CONFIG_BME680_SPI) += bme680_spi.o
> > diff --git a/drivers/iio/chemical/atlas-ezo-sensor.c b/drivers/iio/chemical/atlas-ezo-sensor.c
> > new file mode 100644
> > index 000000000000..1f972f525a46
> > --- /dev/null
> > +++ b/drivers/iio/chemical/atlas-ezo-sensor.c
> > @@ -0,0 +1,173 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * atlas-ezo-sensor.c - Support for Atlas Scientific EZO sensors
> > + *
> > + * Copyright (C) 2020 Konsulko Group
> > + * Author: Matt Ranostay <matt.ranostay@xxxxxxxxxxxx>
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/init.h>
> > +#include <linux/delay.h>
> > +#include <linux/mutex.h>
> > +#include <linux/err.h>
> > +#include <linux/i2c.h>
> > +#include <linux/of_device.h>
> > +#include <linux/iio/iio.h>
> > +
> > +#define ATLAS_EZO_DRV_NAME "atlas-ezo-sensor"
> > +#define ATLAS_CO2_INT_TIME_IN_MS 950
> > +
> > +enum {
> > + ATLAS_CO2_EZO,
> > +};
> > +
> > +struct atlas_ezo_device {
> > + const struct iio_chan_spec *channels;
> > + int num_channels;
> > + int delay;
> > +};
> > +
> > +struct atlas_ezo_data {
> > + struct i2c_client *client;
> > + struct atlas_ezo_device *chip;
>
> const? Seems like it's always a pointer to a constant structure.
>
> > + struct mutex lock;
>
> Locks should 'always' have a comment to say what their scope is.
> Even when it appears obvious ;)
>
> > + u8 buffer[8];
> > +};
> > +
> > +static const struct iio_chan_spec atlas_co2_ezo_channels[] = {
> > + {
> > + .type = IIO_CONCENTRATION,
> > + .modified = 1,
> > + .channel2 = IIO_MOD_CO2,
> > + .info_mask_separate =
> > + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> > + .scan_index = 0,
> > + .scan_type = {
> > + .sign = 'u',
> > + .realbits = 32,
> > + .storagebits = 32,
> > + .endianness = IIO_CPU,
> > + },
> > + },
> > +};
> > +
> > +static struct atlas_ezo_device atlas_ezo_devices[] = {
>
> const?
>
> > + [ATLAS_CO2_EZO] = {
> > + .channels = atlas_co2_ezo_channels,
> > + .num_channels = 1,
> > + .delay = ATLAS_CO2_INT_TIME_IN_MS,
> > + },
> > +};
> > +
> > +static int atlas_ezo_read_raw(struct iio_dev *indio_dev,
> > + struct iio_chan_spec const *chan,
> > + int *val, int *val2, long mask)
> > +{
> > + struct atlas_ezo_data *data = iio_priv(indio_dev);
> > + struct i2c_client *client = data->client;
> > + int ret = 0;
> > +
> > + if (chan->type != IIO_CONCENTRATION)
> > + return -EINVAL;
> > +
> > + switch (mask) {
> > + case IIO_CHAN_INFO_RAW: {
> > + int tmp;
> > +
> > + mutex_lock(&data->lock);
> > +
> > + tmp = i2c_smbus_write_byte(client, 'R');
> > +
> > + if (tmp < 0) {
> > + mutex_unlock(&data->lock);
> > + return tmp;
> > + }
> > +
> > + msleep(data->chip->delay);
> > +
> > + tmp = i2c_master_recv(client, data->buffer, sizeof(data->buffer));
> > +
> > + // Confirm response code is 1 for success
>
> Comment syntax /* */
>
> > + if (tmp < 0 || data->buffer[0] != 1) {
> > + mutex_unlock(&data->lock);
> > + return -EBUSY;
> > + }
> > +
> > + ret = kstrtol(data->buffer + 1, 10, (long *) val);
>
> Use a local variable rather than casting like that which could in theory
> be unsafe.
>
> > +
> > + mutex_unlock(&data->lock);
> > +
> > + return ret ? ret : IIO_VAL_INT;
> > + }
> > + case IIO_CHAN_INFO_SCALE:
> > + *val = 1;
> > + *val2 = 10000; /* 0.0001 */
> > + return IIO_VAL_FRACTIONAL;
>
> Could use VAL_INT_PLUS_MICRO to reduce the maths needed for
> a constant case like we have here where that representation
> is just as easy to read as this one.
>
> > + }
> > +
>
> Can only get here in invalid path. So return -EINVAL and don't
> initialize ret above.
>
> > + return ret;
> > +}
> > +
> > +static const struct iio_info atlas_info = {
> > + .read_raw = atlas_ezo_read_raw,
> > +};
> > +
> > +static const struct i2c_device_id atlas_ezo_id[] = {
> > + { "atlas-co2-ezo", ATLAS_CO2_EZO },
> > + {}
> > +};
> > +MODULE_DEVICE_TABLE(i2c, atlas_ezo_id);
> > +
> > +static const struct of_device_id atlas_ezo_dt_ids[] = {
> > + { .compatible = "atlas,co2-ezo", .data = (void *)ATLAS_CO2_EZO, },
> > + {}
> > +};
> > +MODULE_DEVICE_TABLE(of, atlas_ezo_dt_ids);
> > +
> > +static int atlas_ezo_probe(struct i2c_client *client,
> > + const struct i2c_device_id *id)
> > +{
> > + struct atlas_ezo_data *data;
> > + struct atlas_ezo_device *chip;
> > + const struct of_device_id *of_id;
> > + struct iio_dev *indio_dev;
> > +
> > + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> > + if (!indio_dev)
> > + return -ENOMEM;
> > +
> > + of_id = of_match_device(atlas_dt_ids, &client->dev);
> > + if (!of_id)
> > + chip = &atlas_ezo_devices[id->driver_data];
>
> Given we are supposed to be transitioning away (slowly) from
> probe to probe_new, we shouldn't really be using id to do anything
> in here (directly anyway)
>
> Looking at i2c_of_match_device, there is some magic to match
> if we have initialized through the sysfs interface, so use that
> instead.
>
> https://elixir.bootlin.com/linux/latest/source/drivers/i2c/i2c-core-of.c#L224
>
> I 'think' that takes care of the case where we haven't instantiated
> via device tree.
>
> Interestingly it's a very little used function. But, the original discussion
> included a patch doing pretty much what I'm suggesting here:
>
> https://lore.kernel.org/patchwork/patch/728984/
Looks good but what about ACPI systems like x86? Which now my UP^2 is
my main development system now.
Thanks,
Matt
>
>
> > + else
> > + chip = &atlas_ezo_devices[(unsigned long)of_id->data];
> > +
> > + indio_dev->info = &atlas_info;
> > + indio_dev->name = ATLAS_EZO_DRV_NAME;
> > + indio_dev->channels = chip->channels;
> > + indio_dev->num_channels = chip->num_channels;
> > + indio_dev->modes = INDIO_DIRECT_MODE;
> > + indio_dev->dev.parent = &client->dev;
> > +
> > + data = iio_priv(indio_dev);
> > + data->client = client;
> > + data->chip = chip;
> > + mutex_init(&data->lock);
> > +
> > + return devm_iio_device_register(&client->dev, indio_dev);
> > +};
> > +
> > +static struct i2c_driver atlas_ezo_driver = {
> > + .driver = {
> > + .name = ATLAS_EZO_DRV_NAME,
> > + .of_match_table = atlas_ezo_dt_ids,
> > + },
> > + .probe = atlas_ezo_probe,
> > + .id_table = atlas_ezo_id,
> > +};
> > +module_i2c_driver(atlas_ezo_driver);
> > +
> > +MODULE_AUTHOR("Matt Ranostay <matt.ranostay@xxxxxxxxxxxx>");
> > +MODULE_DESCRIPTION("Atlas Scientific EZO sensors");
> > +MODULE_LICENSE("GPL");
>
