On Mon, Aug 3, 2015 at 1:56 PM, Matt Porter <mporter@xxxxxxxxxxxx> wrote:
> Add a driver for the MAX6675 thermocouple converter. This
> device interfaces with K-type thermocouples and provides
> cold-junction compensated temperature readings via a
> SPI interface.
>
> Signed-off-by: Matt Porter <mporter@xxxxxxxxxxxx>
> ---
> drivers/iio/temperature/Kconfig | 11 +++
> drivers/iio/temperature/Makefile | 1 +
> drivers/iio/temperature/max6675.c | 155 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 167 insertions(+)
> create mode 100644 drivers/iio/temperature/max6675.c
>
> diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig
> index 21feaa4..b73fbf4 100644
> --- a/drivers/iio/temperature/Kconfig
> +++ b/drivers/iio/temperature/Kconfig
> @@ -3,6 +3,17 @@
> #
> menu "Temperature sensors"
>
> +config MAX6675
> + tristate "MAX6675 thermocouple converter"
> + depends on SPI
> + help
> + If you say yes here you get support for the Maxim
> + MAX6675 thermocouple converter connected with SPI.
> +
> + This driver can also be built as a module. If so, the module will
> + be called max6675.
> +
> +
> config MLX90614
> tristate "MLX90614 contact-less infrared sensor"
> depends on I2C
> diff --git a/drivers/iio/temperature/Makefile b/drivers/iio/temperature/Makefile
> index 40710a8..d67ef40 100644
> --- a/drivers/iio/temperature/Makefile
> +++ b/drivers/iio/temperature/Makefile
> @@ -2,5 +2,6 @@
> # Makefile for industrial I/O temperature drivers
> #
>
> +obj-$(CONFIG_MAX6675) += max6675.o
> obj-$(CONFIG_MLX90614) += mlx90614.o
> obj-$(CONFIG_TMP006) += tmp006.o
> diff --git a/drivers/iio/temperature/max6675.c b/drivers/iio/temperature/max6675.c
> new file mode 100644
> index 0000000..2d1fda2
> --- /dev/null
> +++ b/drivers/iio/temperature/max6675.c
> @@ -0,0 +1,155 @@
> +/*
> + * max6675.c - MAX6675 thermocouple converter driver
> + *
> + * Copyright (C) 2015 Konsulko Group, Matt Porter <mporter@xxxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/iio/iio.h>
> +#include <linux/spi/spi.h>
> +
> +struct max6675_state {
> + struct spi_device *spi;
> +};
> +
> +static const struct iio_chan_spec max6675_channels[] = {
> + {
> + .type = IIO_TEMP,
> + .info_mask_separate =
> + BIT(IIO_CHAN_INFO_RAW) |
> + BIT(IIO_CHAN_INFO_SCALE),
> + },
> +};
> +
> +static int max6675_read(struct max6675_state *st, int *val)
> +{
> + int ret;
> +
> + ret = spi_read(st->spi, val, 2);
> + if (ret < 0)
> + return ret;
> +
> + /* Temperature is bits 14..3 */
> + *val = (*val >> 3) & 0xfff;
> +
> + return ret;
> +}
> +
> +static int max6675_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val,
> + int *val2,
> + long m)
> +{
> + struct max6675_state *st = iio_priv(indio_dev);
> + int ret;
> +
> + if (m == IIO_CHAN_INFO_RAW) {
> + *val2 = 0;
> + ret = max6675_read(st, val);
> + if (ret)
> + return ret;
> + } else if (m == IIO_CHAN_INFO_SCALE) {
> + *val = 250;
> + *val2 = 0;
> + } else
> + return -EINVAL;
> +
> + return IIO_VAL_INT;
> +}
> +
> +static const struct iio_info max6675_info = {
> + .driver_module = THIS_MODULE,
> + .read_raw = &max6675_read_raw,
> +};
> +
> +static int max6675_probe(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev;
> + struct max6675_state *st;
> + int ret = 0;
> +
> + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + st = iio_priv(indio_dev);
> + st->spi = spi;
> +
> + spi->mode = SPI_MODE_1;
> + spi->bits_per_word = 16;
Have this error or display a warning when it doesn't match the passed
DT binding settings. Otherwise it may get confusing why other SPI
modes and word sizes don't work.
> +
> + spi_set_drvdata(spi, indio_dev);
> +
> + indio_dev->dev.parent = &spi->dev;
> + indio_dev->name = spi_get_device_id(spi)->name;
> + indio_dev->channels = max6675_channels;
> + indio_dev->num_channels = ARRAY_SIZE(max6675_channels);
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->info = &max6675_info;
> +
> + ret = iio_device_register(indio_dev);
> + if (ret < 0)
> + dev_err(&spi->dev, "unable to register device\n");
> +
> + return ret;
> +}
> +
> +static int max6675_remove(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +
> + iio_device_unregister(indio_dev);
> +
> + return 0;
> +}
> +
> +static const struct acpi_device_id max6675_acpi_ids[] = {
> + { "MXIM6675", 0 },
> + {},
> +};
> +MODULE_DEVICE_TABLE(acpi, max6675_acpi_ids);
> +
> +static const struct of_device_id max6675_dt_ids[] = {
> + { .compatible = "maxim,max6675" },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, max6675_dt_ids);
> +
> +static const struct spi_device_id max6675_spi_ids[] = {
> + {"max6675", 0},
> + {},
> +};
> +MODULE_DEVICE_TABLE(spi, max6675_spi_ids);
> +
> +static struct spi_driver max6675_driver = {
> + .driver = {
> + .name = "max6675",
> + .owner = THIS_MODULE,
> + .acpi_match_table = ACPI_PTR(max6675_acpi_ids),
> + .of_match_table = of_match_ptr(max6675_dt_ids),
> + },
> + .probe = max6675_probe,
> + .remove = max6675_remove,
> + .id_table = max6675_spi_ids,
> +};
> +module_spi_driver(max6675_driver);
> +
> +MODULE_AUTHOR("Matt Porter <mporter@xxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("MAX6675 thermocouple converter driver");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("spi:max6675");
> --
> 2.1.4
>
> --
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