Add initial driver support for MAX6675, and MAX31885 thermocouple chips. Cc: Marek Vasut <marex@xxxxxxx> Cc: Matt Porter <mporter@xxxxxxxxxxxx> Signed-off-by: Matt Ranostay <mranostay@xxxxxxxxx> --- Changes from v1: * switch to iio_device_*_direct_mode wrappers * add const to structs * removed useless cast Changes from v2: * mark buffer data invalid on disconnected thermocouple * add .address = 0 to be consistent * add missing scan_mask for the max31855 part .../iio/temperature/maxim_thermocouple.txt | 21 ++ drivers/iio/temperature/Kconfig | 14 + drivers/iio/temperature/Makefile | 1 + drivers/iio/temperature/maxim_thermocouple.c | 300 +++++++++++++++++++++ 4 files changed, 336 insertions(+) create mode 100644 Documentation/devicetree/bindings/iio/temperature/maxim_thermocouple.txt create mode 100644 drivers/iio/temperature/maxim_thermocouple.c diff --git a/Documentation/devicetree/bindings/iio/temperature/maxim_thermocouple.txt b/Documentation/devicetree/bindings/iio/temperature/maxim_thermocouple.txt new file mode 100644 index 0000000..44fb029 --- /dev/null +++ b/Documentation/devicetree/bindings/iio/temperature/maxim_thermocouple.txt @@ -0,0 +1,21 @@ +Maxim thermocouple support + +* https://datasheets.maximintegrated.com/en/ds/MAX6675.pdf +* https://datasheets.maximintegrated.com/en/ds/MAX31855.pdf + +Required properties: + + - compatible: must be "maxim,max31885" or "maxim,max6675" + - reg: SPI chip select number for the device + - spi-max-frequency: must be 4300000 + - spi-cpha: must be defined for max6675 to enable SPI mode 1 + + Refer to spi/spi-bus.txt for generic SPI slave bindings. + +Example: + + max31885@0 { + compatible = "maxim,max31885"; + reg = <0>; + spi-max-frequency = <4300000>; + }; diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig index c4664e5..c9f5342 100644 --- a/drivers/iio/temperature/Kconfig +++ b/drivers/iio/temperature/Kconfig @@ -3,6 +3,20 @@ # menu "Temperature sensors" +config MAXIM_THERMOCOUPLE + tristate "Maxim thermocouple sensors" + depends on SPI + help + If you say yes here you get support for the Maxim series of + thermocouple sensors connected via SPI. + + Supported sensors: + * MAX6675 + * MAX31885 + + This driver can also be built as a module. If so, the module will + be called maxim_thermocouple. + config MLX90614 tristate "MLX90614 contact-less infrared sensor" depends on I2C diff --git a/drivers/iio/temperature/Makefile b/drivers/iio/temperature/Makefile index 02bc79d..78c3de0 100644 --- a/drivers/iio/temperature/Makefile +++ b/drivers/iio/temperature/Makefile @@ -2,6 +2,7 @@ # Makefile for industrial I/O temperature drivers # +obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o obj-$(CONFIG_MLX90614) += mlx90614.o obj-$(CONFIG_TMP006) += tmp006.o obj-$(CONFIG_TSYS01) += tsys01.o diff --git a/drivers/iio/temperature/maxim_thermocouple.c b/drivers/iio/temperature/maxim_thermocouple.c new file mode 100644 index 0000000..59ef7fd --- /dev/null +++ b/drivers/iio/temperature/maxim_thermocouple.c @@ -0,0 +1,300 @@ +/* + * maxim_thermocouple.c - Support for Maxim thermocouple chips + * + * Copyright (C) 2016 Matt Ranostay <mranostay@xxxxxxxxx> + * + * 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/module.h> +#include <linux/init.h> +#include <linux/mutex.h> +#include <linux/err.h> +#include <linux/spi/spi.h> +#include <linux/iio/iio.h> +#include <linux/iio/trigger.h> +#include <linux/iio/buffer.h> +#include <linux/iio/triggered_buffer.h> +#include <linux/iio/trigger_consumer.h> + +#define MAXIM_THERMOCOUPLE_DRV_NAME "maxim_thermocouple" + +enum { + MAX6675, + MAX31885, +}; + +const struct iio_chan_spec max6675_channels[] = { + { /* thermocouple temperature */ + .type = IIO_TEMP, + .info_mask_separate = + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + .scan_index = 0, + .scan_type = { + .sign = 's', + .realbits = 13, + .storagebits = 16, + .shift = 3, + .endianness = IIO_BE, + }, + }, + IIO_CHAN_SOFT_TIMESTAMP(1), +}; + +const struct iio_chan_spec max31885_channels[] = { + { /* thermocouple temperature */ + .type = IIO_TEMP, + .address = 2, + .info_mask_separate = + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + .scan_index = 0, + .scan_type = { + .sign = 's', + .realbits = 14, + .storagebits = 16, + .shift = 2, + .endianness = IIO_BE, + }, + }, + { /* cold junction temperature */ + .type = IIO_TEMP, + .address = 0, + .channel2 = IIO_MOD_TEMP_AMBIENT, + .modified = 1, + .info_mask_separate = + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + .scan_index = 1, + .scan_type = { + .sign = 's', + .realbits = 12, + .storagebits = 16, + .shift = 4, + .endianness = IIO_BE, + }, + }, + IIO_CHAN_SOFT_TIMESTAMP(2), +}; + +static const unsigned long max31885_scan_masks[] = {0x3, 0}; + +struct maxim_thermocouple_chip { + const struct iio_chan_spec *channels; + const unsigned long *scan_masks; + int num_channels; + int read_size; + + /* bit-check for valid input */ + int status_bit; +}; + +const struct maxim_thermocouple_chip maxim_thermocouple_chips[] = { + [MAX6675] = { + .channels = max6675_channels, + .num_channels = ARRAY_SIZE(max6675_channels), + .read_size = 2, + .status_bit = BIT(2), + }, + [MAX31885] = { + .channels = max31885_channels, + .num_channels = ARRAY_SIZE(max31885_channels), + .read_size = 4, + .scan_masks = max31885_scan_masks, + .status_bit = BIT(16), + }, +}; + +struct maxim_thermocouple_data { + struct spi_device *spi; + const struct maxim_thermocouple_chip *chip; + + u8 buffer[16]; /* 4 byte data + 4 byte padding + 8 byte timestamp */ +}; + +static int maxim_thermocouple_read(struct maxim_thermocouple_data *data, + struct iio_chan_spec const *chan, int *val) +{ + unsigned int storage_bytes = data->chip->read_size; + unsigned int shift = chan->scan_type.shift + (chan->address * 8); + unsigned int buf; + int ret; + + ret = spi_read(data->spi, (void *) &buf, storage_bytes); + if (ret) + return ret; + + switch (storage_bytes) { + case 2: + *val = be16_to_cpu(buf); + break; + case 4: + *val = be32_to_cpu(buf); + break; + } + + /* check to be sure this is a valid reading */ + if (*val & data->chip->status_bit) + return -EINVAL; + + *val = sign_extend32(*val >> shift, chan->scan_type.realbits - 1); + + return 0; +} + +static void maxim_thermocouple_validate_buffer(struct maxim_thermocouple_data *data) +{ + unsigned int storage_bytes = data->chip->read_size; + unsigned int *buf = (unsigned int *) data->buffer; + int tmp = 0; + + switch (storage_bytes) { + case 2: + tmp = be16_to_cpu(*buf); + break; + case 4: + tmp = be32_to_cpu(*buf); + break; + } + + /* check to be sure this is a valid reading, mark result -1 if not */ + if (tmp & data->chip->status_bit) + memset(data->buffer, 0xff, storage_bytes); +} + +static irqreturn_t maxim_thermocouple_trigger_handler(int irq, void *private) +{ + struct iio_poll_func *pf = private; + struct iio_dev *indio_dev = pf->indio_dev; + struct maxim_thermocouple_data *data = iio_priv(indio_dev); + int ret; + + ret = spi_read(data->spi, data->buffer, data->chip->read_size); + if (!ret) { + maxim_thermocouple_validate_buffer(data); + iio_push_to_buffers_with_timestamp(indio_dev, data->buffer, + iio_get_time_ns()); + } + + iio_trigger_notify_done(indio_dev->trig); + + return IRQ_HANDLED; +} + +static int maxim_thermocouple_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct maxim_thermocouple_data *data = iio_priv(indio_dev); + int ret = -EINVAL; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + if (iio_device_claim_direct_mode(indio_dev)) + return -EBUSY; + + ret = maxim_thermocouple_read(data, chan, val); + if (!ret) + ret = IIO_VAL_INT; + + iio_device_release_direct_mode(indio_dev); + break; + case IIO_CHAN_INFO_SCALE: + switch (chan->channel2) { + case IIO_MOD_TEMP_AMBIENT: + *val = 62; + *val2 = 500000; /* 1000 * 0.0625 */ + ret = IIO_VAL_INT_PLUS_MICRO; + break; + default: + *val = 250; /* 1000 * 0.25 */ + ret = IIO_VAL_INT; + }; + break; + } + + return ret; +} + +static const struct iio_info maxim_thermocouple_info = { + .driver_module = THIS_MODULE, + .read_raw = maxim_thermocouple_read_raw, +}; + +static int maxim_thermocouple_probe(struct spi_device *spi) +{ + const struct spi_device_id *id = spi_get_device_id(spi); + struct iio_dev *indio_dev; + struct maxim_thermocouple_data *data; + const struct maxim_thermocouple_chip *chip = + &maxim_thermocouple_chips[id->driver_data]; + int ret; + + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data)); + if (!indio_dev) + return -ENOMEM; + + indio_dev->info = &maxim_thermocouple_info; + indio_dev->name = MAXIM_THERMOCOUPLE_DRV_NAME; + indio_dev->channels = chip->channels; + indio_dev->available_scan_masks = chip->scan_masks; + indio_dev->num_channels = chip->num_channels; + indio_dev->modes = INDIO_DIRECT_MODE; + + data = iio_priv(indio_dev); + data->spi = spi; + data->chip = chip; + + ret = iio_triggered_buffer_setup(indio_dev, NULL, + maxim_thermocouple_trigger_handler, NULL); + if (ret) + return ret; + + ret = iio_device_register(indio_dev); + if (ret) + goto error_unreg_buffer; + + return 0; + +error_unreg_buffer: + iio_triggered_buffer_cleanup(indio_dev); + + return ret; +} + +static int maxim_thermocouple_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + + iio_device_unregister(indio_dev); + iio_triggered_buffer_cleanup(indio_dev); + + return 0; +} + +static const struct spi_device_id maxim_thermocouple_id[] = { + {"max6675", MAX6675}, + {"max31885", MAX31885}, + {}, +}; +MODULE_DEVICE_TABLE(spi, maxim_thermocouple_id); + +static struct spi_driver maxim_thermocouple_driver = { + .driver = { + .name = MAXIM_THERMOCOUPLE_DRV_NAME, + }, + .probe = maxim_thermocouple_probe, + .remove = maxim_thermocouple_remove, + .id_table = maxim_thermocouple_id, +}; +module_spi_driver(maxim_thermocouple_driver); + +MODULE_AUTHOR("Matt Ranostay <mranostay@xxxxxxxxx>"); +MODULE_DESCRIPTION("Maxim thermocouple sensors"); +MODULE_LICENSE("GPL"); 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