* [PATCH v5] iio: temperature: add support for Maxim thermocouple chips
@ 2016-07-01 2:52 Matt Ranostay
2016-07-01 10:55 ` Marek Vasut
0 siblings, 1 reply; 4+ messages in thread
From: Matt Ranostay @ 2016-07-01 2:52 UTC (permalink / raw)
To: linux-iio; +Cc: jic23, Matt Ranostay, Marek Vasut, Matt Porter
Add initial driver support for MAX6675, and MAX31855 thermocouple chips.
Cc: Marek Vasut <marex@denx.de>
Cc: Matt Porter <mporter@konsulko.com>
Signed-off-by: Matt Ranostay <mranostay@gmail.com>
---
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
Changes from v3:
* fixed several typos of max31855 part number
Changes from v4:
* drop maxim_thermocouple_validate_buffer() due to peer review saying
this is an incorrect way to signal an invalid reading
.../iio/temperature/maxim_thermocouple.txt | 21 ++
drivers/iio/temperature/Kconfig | 14 ++
drivers/iio/temperature/Makefile | 1 +
drivers/iio/temperature/maxim_thermocouple.c | 279 +++++++++++++++++++++
4 files changed, 315 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 000000000000..28bc5c4d965b
--- /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,max31855" 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:
+
+ max31855@0 {
+ compatible = "maxim,max31855";
+ reg = <0>;
+ spi-max-frequency = <4300000>;
+ };
diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig
index c4664e5de791..1d3da05eca39 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
+ * MAX31855
+
+ 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 02bc79d49b24..78c3de0dc3f0 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 000000000000..23c304676364
--- /dev/null
+++ b/drivers/iio/temperature/maxim_thermocouple.c
@@ -0,0 +1,279 @@
+/*
+ * maxim_thermocouple.c - Support for Maxim thermocouple chips
+ *
+ * Copyright (C) 2016 Matt Ranostay <mranostay@gmail.com>
+ *
+ * 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,
+ MAX31855,
+};
+
+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 max31855_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 max31855_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),
+ },
+ [MAX31855] = {
+ .channels = max31855_channels,
+ .num_channels = ARRAY_SIZE(max31855_channels),
+ .read_size = 4,
+ .scan_masks = max31855_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 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) {
+ 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},
+ {"max31855", MAX31855},
+ {},
+};
+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@gmail.com>");
+MODULE_DESCRIPTION("Maxim thermocouple sensors");
+MODULE_LICENSE("GPL");
--
2.7.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v5] iio: temperature: add support for Maxim thermocouple chips
2016-07-01 2:52 [PATCH v5] iio: temperature: add support for Maxim thermocouple chips Matt Ranostay
@ 2016-07-01 10:55 ` Marek Vasut
2016-07-04 5:37 ` Matt Ranostay
0 siblings, 1 reply; 4+ messages in thread
From: Marek Vasut @ 2016-07-01 10:55 UTC (permalink / raw)
To: Matt Ranostay, linux-iio; +Cc: jic23, Matt Porter
On 07/01/2016 04:52 AM, Matt Ranostay wrote:
> Add initial driver support for MAX6675, and MAX31855 thermocouple chips.
>
> Cc: Marek Vasut <marex@denx.de>
> Cc: Matt Porter <mporter@konsulko.com>
> Signed-off-by: Matt Ranostay <mranostay@gmail.com>
> ---
>
> 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
>
> Changes from v3:
> * fixed several typos of max31855 part number
>
> Changes from v4:
> * drop maxim_thermocouple_validate_buffer() due to peer review saying
> this is an incorrect way to signal an invalid reading
[...]
> +const struct iio_chan_spec max31855_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 max31855_scan_masks[] = {0x3, 0};
> +
> +struct maxim_thermocouple_chip {
> + const struct iio_chan_spec *channels;
> + const unsigned long *scan_masks;
> + int num_channels;
const u8 or u32 ?
> + int read_size;
const u8
> + /* bit-check for valid input */
> + int status_bit;
const bool ?
You can save some slop in here, see also:
http://www.catb.org/esr/structure-packing/
> +};
> +
> +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),
> + },
> + [MAX31855] = {
> + .channels = max31855_channels,
> + .num_channels = ARRAY_SIZE(max31855_channels),
> + .read_size = 4,
> + .scan_masks = max31855_scan_masks,
> + .status_bit = BIT(16),
> + },
> +};
[...]
--
Best regards,
Marek Vasut
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v5] iio: temperature: add support for Maxim thermocouple chips
2016-07-01 10:55 ` Marek Vasut
@ 2016-07-04 5:37 ` Matt Ranostay
2016-07-05 1:21 ` Matt Ranostay
0 siblings, 1 reply; 4+ messages in thread
From: Matt Ranostay @ 2016-07-04 5:37 UTC (permalink / raw)
To: Marek Vasut; +Cc: linux-iio, Jonathan Cameron, Matt Porter
On Fri, Jul 1, 2016 at 3:55 AM, Marek Vasut <marex@denx.de> wrote:
> On 07/01/2016 04:52 AM, Matt Ranostay wrote:
>> Add initial driver support for MAX6675, and MAX31855 thermocouple chips.
>>
>> Cc: Marek Vasut <marex@denx.de>
>> Cc: Matt Porter <mporter@konsulko.com>
>> Signed-off-by: Matt Ranostay <mranostay@gmail.com>
>> ---
>>
>> 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
>>
>> Changes from v3:
>> * fixed several typos of max31855 part number
>>
>> Changes from v4:
>> * drop maxim_thermocouple_validate_buffer() due to peer review saying
>> this is an incorrect way to signal an invalid reading
>
> [...]
>
>> +const struct iio_chan_spec max31855_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 max31855_scan_masks[] = {0x3, 0};
>> +
>> +struct maxim_thermocouple_chip {
>> + const struct iio_chan_spec *channels;
>> + const unsigned long *scan_masks;
>> + int num_channels;
>
> const u8 or u32 ?
>
>> + int read_size;
>
> const u8
Ok not sure saving 2 or 4 bytes of memory really matters that much :).
>
>> + /* bit-check for valid input */
>> + int status_bit;
>
> const bool ?
It is a bitmask of a single bit for the validation. I guess it could
be const u32
>
> You can save some slop in here, see also:
> http://www.catb.org/esr/structure-packing/
>
>> +};
>> +
>> +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),
>> + },
>> + [MAX31855] = {
>> + .channels = max31855_channels,
>> + .num_channels = ARRAY_SIZE(max31855_channels),
>> + .read_size = 4,
>> + .scan_masks = max31855_scan_masks,
>> + .status_bit = BIT(16),
>> + },
>> +};
> [...]
>
> --
> Best regards,
> Marek Vasut
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v5] iio: temperature: add support for Maxim thermocouple chips
2016-07-04 5:37 ` Matt Ranostay
@ 2016-07-05 1:21 ` Matt Ranostay
0 siblings, 0 replies; 4+ messages in thread
From: Matt Ranostay @ 2016-07-05 1:21 UTC (permalink / raw)
To: Marek Vasut; +Cc: linux-iio, Jonathan Cameron, Matt Porter
On Sun, Jul 3, 2016 at 10:37 PM, Matt Ranostay <mranostay@gmail.com> wrote:
> On Fri, Jul 1, 2016 at 3:55 AM, Marek Vasut <marex@denx.de> wrote:
>> On 07/01/2016 04:52 AM, Matt Ranostay wrote:
>>> Add initial driver support for MAX6675, and MAX31855 thermocouple chips.
>>>
>>> Cc: Marek Vasut <marex@denx.de>
>>> Cc: Matt Porter <mporter@konsulko.com>
>>> Signed-off-by: Matt Ranostay <mranostay@gmail.com>
>>> ---
>>>
>>> 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
>>>
>>> Changes from v3:
>>> * fixed several typos of max31855 part number
>>>
>>> Changes from v4:
>>> * drop maxim_thermocouple_validate_buffer() due to peer review saying
>>> this is an incorrect way to signal an invalid reading
>>
>> [...]
>>
>>> +const struct iio_chan_spec max31855_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 max31855_scan_masks[] = {0x3, 0};
>>> +
>>> +struct maxim_thermocouple_chip {
>>> + const struct iio_chan_spec *channels;
>>> + const unsigned long *scan_masks;
>>> + int num_channels;
>>
>> const u8 or u32 ?
>>
>>> + int read_size;
>>
>> const u8
>
> Ok not sure saving 2 or 4 bytes of memory really matters that much :).
Although I make it part of v6.. since I noticed the buffer isn't
cachealigned as well
>
>>
>>> + /* bit-check for valid input */
>>> + int status_bit;
>>
>> const bool ?
>
> It is a bitmask of a single bit for the validation. I guess it could
> be const u32
>>
>> You can save some slop in here, see also:
>> http://www.catb.org/esr/structure-packing/
>>
>>> +};
>>> +
>>> +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),
>>> + },
>>> + [MAX31855] = {
>>> + .channels = max31855_channels,
>>> + .num_channels = ARRAY_SIZE(max31855_channels),
>>> + .read_size = 4,
>>> + .scan_masks = max31855_scan_masks,
>>> + .status_bit = BIT(16),
>>> + },
>>> +};
>> [...]
>>
>> --
>> Best regards,
>> Marek Vasut
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2016-07-05 1:21 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-07-01 2:52 [PATCH v5] iio: temperature: add support for Maxim thermocouple chips Matt Ranostay
2016-07-01 10:55 ` Marek Vasut
2016-07-04 5:37 ` Matt Ranostay
2016-07-05 1:21 ` Matt Ranostay
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