On Wed, 20 Nov 2019 15:47:54 +0100
Andrea Merello <andrea.merello@xxxxxxxxx> wrote:
> The sensor support various thermocouple types (e.g. J, K, N, ...). The
> driver allows to configure this parameter using a DT property.
>
> This is useful when i.e. the thermocouple is physically tied to the sensor
> and it is usually not removed, or when it is at least known in advance
> which sensor will be connected to the circuit.
>
> However, if the user can randomly connect any kind of thermocouples (i.e.
> the device exposes a connector, and the user is free to connect its own
> sensors), it would be more appropriate to provide a mechanism to
> dynamically switch from one thermocouple type to another. This can be i.e.
> handled in userspace by a GUI, a configuration file or a program that
> detects the thermocouple type by reading a GPIO, or a eeprom on the probe,
> or whatever.
>
> This patch adds a IIO attribute that can be used to override, at run-time,
> the DT-provided setting (which serves as default).
>
> Cc: Hartmut Knaack <knaack.h@xxxxxx>
> Cc: Lars-Peter Clausen <lars@xxxxxxxxxx>
> Cc: Peter Meerwald-Stadler <pmeerw@xxxxxxxxxx>
> Cc: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> Cc: Patrick Havelange <patrick.havelange@xxxxxxxxxxxxx>
> Cc: Matt Weber <matthew.weber@xxxxxxxxxxxxxxxxxxx>
> Cc: Matt Ranostay <matt.ranostay@xxxxxxxxxxxx>
> Cc: Chuhong Yuan <hslester96@xxxxxxxxx>
> Cc: Daniel Gomez <dagmcr@xxxxxxxxx>
> Cc: linux-iio@xxxxxxxxxxxxxxx
> Signed-off-by: Andrea Merello <andrea.merello@xxxxxxxxx>
Applied to the togreg branch of iio.git and pushed out as testing for
the autobuilders to play with it.
thanks,
Jonathan
> ---
> drivers/iio/temperature/max31856.c | 41 +++++++++++++++++++++++++++++-
> 1 file changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/temperature/max31856.c b/drivers/iio/temperature/max31856.c
> index 8457ca9ae326..4952e89c00bb 100644
> --- a/drivers/iio/temperature/max31856.c
> +++ b/drivers/iio/temperature/max31856.c
> @@ -6,6 +6,7 @@
> * Copyright (C) 2018-2019 Rockwell Collins
> */
>
> +#include <linux/ctype.h>
> #include <linux/module.h>
> #include <linux/init.h>
> #include <linux/err.h>
> @@ -53,7 +54,8 @@ static const struct iio_chan_spec max31856_channels[] = {
> { /* Thermocouple Temperature */
> .type = IIO_TEMP,
> .info_mask_separate =
> - BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) |
> + BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE),
> .info_mask_shared_by_type =
> BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO)
> },
> @@ -75,6 +77,10 @@ struct max31856_data {
> int averaging;
> };
>
> +const char max31856_tc_types[] = {
> + 'B', 'E', 'J', 'K', 'N', 'R', 'S', 'T'
> +};
> +
> static int max31856_read(struct max31856_data *data, u8 reg,
> u8 val[], unsigned int read_size)
> {
> @@ -232,6 +238,9 @@ static int max31856_read_raw(struct iio_dev *indio_dev,
> case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> *val = 1 << data->averaging;
> return IIO_VAL_INT;
> + case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
> + *val = max31856_tc_types[data->thermocouple_type];
> + return IIO_VAL_CHAR;
> default:
> ret = -EINVAL;
> break;
> @@ -240,6 +249,18 @@ static int max31856_read_raw(struct iio_dev *indio_dev,
> return ret;
> }
>
> +static int max31856_write_raw_get_fmt(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + long mask)
> +{
> + switch (mask) {
> + case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
> + return IIO_VAL_CHAR;
> + default:
> + return IIO_VAL_INT;
> + }
> +}
> +
> static int max31856_write_raw(struct iio_dev *indio_dev,
> struct iio_chan_spec const *chan,
> int val, int val2, long mask)
> @@ -259,7 +280,24 @@ static int max31856_write_raw(struct iio_dev *indio_dev,
> data->averaging = msb;
> max31856_init(data);
> break;
> + case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
> + {
> + int tc_type = -1;
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(max31856_tc_types); i++) {
> + if (max31856_tc_types[i] == toupper(val)) {
> + tc_type = i;
> + break;
> + }
> + }
> + if (tc_type < 0)
> + return -EINVAL;
>
> + data->thermocouple_type = tc_type;
> + max31856_init(data);
> + break;
> + }
> default:
> return -EINVAL;
> }
> @@ -356,6 +394,7 @@ static const struct attribute_group max31856_group = {
> static const struct iio_info max31856_info = {
> .read_raw = max31856_read_raw,
> .write_raw = max31856_write_raw,
> + .write_raw_get_fmt = max31856_write_raw_get_fmt,
> .attrs = &max31856_group,
> };
>
