> From: Mårten Lindahl <martenli@xxxxxxxx>
comments below
> This adds support for the Texas Instruments ADC084S021 ADC chip.
>
> Signed-off-by: Mårten Lindahl <martenli@xxxxxxxx>
> ---
> .../devicetree/bindings/iio/adc/ti-adc084s021.txt | 25 ++
> drivers/iio/adc/Kconfig | 12 +
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/ti-adc084s021.c | 342 +++++++++++++++++++++
> 4 files changed, 380 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/iio/adc/ti-adc084s021.txt
> create mode 100644 drivers/iio/adc/ti-adc084s021.c
>
> diff --git a/Documentation/devicetree/bindings/iio/adc/ti-adc084s021.txt b/Documentation/devicetree/bindings/iio/adc/ti-adc084s021.txt
> new file mode 100644
> index 0000000..921eb46
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/ti-adc084s021.txt
> @@ -0,0 +1,25 @@
> +* Texas Instruments' ADC084S021
> +
> +Required properties:
> + - compatible : Must be "ti,adc084s021"
> + - reg : SPI chip select number for the device
> + - vref-supply : The regulator supply for ADC reference voltage
> + - spi-max-frequency : Definition as per Documentation/devicetree/bindings/spi/spi-bus.txt
> +
> +Optional properties:
> + - spi-cpol : SPI inverse clock polarity, as per spi-bus bindings
> + - spi-cpha : SPI shifted clock phase (CPHA), as per spi-bus bindings
> + - spi-cs-high : SPI chip select active high, as per spi-bus bindings
> +
> +
> +Example:
> +adc@0 {
> + compatible = "ti,adc084s021";
> + reg = <0>;
> + vref-supply = <&adc_vref>;
> + spi-cpol;
> + spi-cpha;
> + spi-cs-high;
> + spi-max-frequency = <16000000>;
> + pl022,com-mode = <0x2>; /* DMA */
what is this?
> +};
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index dedae7a..13141e5 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -560,6 +560,18 @@ config TI_ADC0832
> This driver can also be built as a module. If so, the module will be
> called ti-adc0832.
>
> +config TI_ADC084S021
> + tristate "Texas Instruments ADC084S021"
> + depends on SPI
> + select IIO_BUFFER
> + select IIO_TRIGGERED_BUFFER
> + help
> + If you say yes here you get support for Texas Instruments ADC084S021
> + chips.
> +
> + This driver can also be built as a module. If so, the module will be
> + called ti-adc084s021.
> +
> config TI_ADC12138
> tristate "Texas Instruments ADC12130/ADC12132/ADC12138"
> depends on SPI
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index d001262..b1a6158 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -51,6 +51,7 @@ obj-$(CONFIG_STM32_ADC_CORE) += stm32-adc-core.o
> obj-$(CONFIG_STM32_ADC) += stm32-adc.o
> obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
> obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
> +obj-$(CONFIG_TI_ADC084S021) += ti-adc084s021.o
> obj-$(CONFIG_TI_ADC12138) += ti-adc12138.o
> obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
> obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
> diff --git a/drivers/iio/adc/ti-adc084s021.c b/drivers/iio/adc/ti-adc084s021.c
> new file mode 100644
> index 0000000..4f33b91
> --- /dev/null
> +++ b/drivers/iio/adc/ti-adc084s021.c
> @@ -0,0 +1,342 @@
> +/**
> + * Copyright (C) 2017 Axis Communications AB
> + *
> + * Driver for Texas Instruments' ADC084S021 ADC chip.
> + * Datasheets can be found here:
> + * http://www.ti.com/lit/ds/symlink/adc084s021.pdf
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/spi/spi.h>
> +#include <linux/module.h>
> +#include <linux/interrupt.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/events.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/regulator/consumer.h>
> +
> +#define MODULE_NAME "adc084s021"
> +#define DRIVER_VERSION "1.0"
is only used once at the very end...
> +#define ADC_RESOLUTION 8
> +#define ADC_N_CHANNELS 4
we want a consistent prefix, such as ADC084S021_
> +
> +struct adc084s021_configuration {
> + const struct iio_chan_spec *channels;
> + u8 num_channels;
no need for u8, perhaps unsigned?
> +};
> +
> +struct adc084s021 {
> + struct spi_device *spi;
> + struct spi_message message;
> + struct spi_transfer spi_trans[2];
> + struct regulator *reg;
> + struct mutex lock;
> + /*
> + * DMA (thus cache coherency maintenance) requires the
> + * transfer buffers to live in their own cache lines.
> + */
> + union {
> + u8 tx_buf[2];
> + u8 rx_buf[2];
> + } ____cacheline_aligned;
> + u8 cur_adc_values[ADC_N_CHANNELS];
> +};
> +
> +/**
> + * Event triggered when value changes on a channel
> + */
> +static const struct iio_event_spec adc084s021_event = {
> + .type = IIO_EV_TYPE_CHANGE,
> + .dir = IIO_EV_DIR_NONE,
> +};
> +
> +/**
> + * Channel specification
> + */
> +#define ADC084S021_VOLTAGE_CHANNEL(num) \
> + { \
> + .type = IIO_VOLTAGE, \
> + .channel = (num), \
> + .address = (num << 3), \
parenthesis should be around (num)
> + .indexed = 1, \
> + .scan_index = num, \
parenthesis?
> + .scan_type = { \
> + .sign = 'u', \
> + .realbits = 8, \
> + .storagebits = 32, \
> + .shift = 24 - ((num << 3)), \
no need for (( )) around the expression, parenthesis should be around num
the shift doesn't make sense, you are shifting in
adc084s021_adc_conversion() already and return just 8 bits (so storagebits
should be 8)?
you could/should use realbits = 8, storagebits = 16, shift = 4 and
endianness = IIO_BE if I read Figure 1 of the datasheet correctly
> + }, \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
likely this is missing _SCALE
IIO expects data to be returned in millivolt, see
Documentation/ABI/testing/sysfs-bus-iio
> + .event_spec = &adc084s021_event, \
> + .num_event_specs = 1, \
ARRAY_SIZE(&adc084s021_event) to be extensible?
> + }
> +
> +static const struct iio_chan_spec adc084s021_channels[] = {
> + ADC084S021_VOLTAGE_CHANNEL(0),
> + ADC084S021_VOLTAGE_CHANNEL(1),
> + ADC084S021_VOLTAGE_CHANNEL(2),
> + ADC084S021_VOLTAGE_CHANNEL(3),
> + IIO_CHAN_SOFT_TIMESTAMP(4),
> +};
> +
> +static const struct adc084s021_configuration adc084s021_config[] = {
> + { adc084s021_channels, ARRAY_SIZE(adc084s021_channels) },
for just one configuration, this is not really needed; so you plan/forsee
more chips being added soonish?
> +};
> +
> +/**
> + * Read an ADC channel and return its value.
> + *
> + * @adc: The ADC SPI data.
> + * @channel: The IIO channel data structure.
> + */
> +static int adc084s021_adc_conversion(struct adc084s021 *adc,
> + struct iio_chan_spec const *channel)
> +{
> + u16 value;
value should be u8, but is not really needed
> + int ret;
> +
> + mutex_lock(&adc->lock);
> + adc->tx_buf[0] = channel->address;
> +
> + /* Do the transfer */
> + ret = spi_sync(adc->spi, &adc->message);
> +
no newline here please
> + if (ret < 0) {
> + mutex_unlock(&adc->lock);
> + return ret;
> + }
> +
> + value = (adc->rx_buf[0] << 4) | (adc->rx_buf[1] >> 4);
I recommend using __be16 for rx_buf and
ret = (be16_to_cpu(adc->rx_buf) >> 4) & 0xff;
> + mutex_unlock(&adc->lock);
> +
> + dev_dbg(&adc->spi->dev, "value 0x%02X on channel %d\n",
> + value, channel->channel);
> + return value;
> +}
> +
> +/**
> + * Make a readout of requested IIO channel info.
no need to document this, it is found in every IIO driver...
> + *
> + * @indio_dev: The industrial I/O device.
> + * @channel: The IIO channel data structure.
> + * @val: First element of value (integer).
> + * @val2: Second element of value (fractional).
> + * @mask: The info_mask to read.
> + */
> +static int adc084s021_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *channel, int *val,
> + int *val2, long mask)
> +{
> + struct adc084s021 *adc = iio_priv(indio_dev);
> + int retval;
how about using ret everywhere?
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
probably want iio_device_claim_direct_mode() so to not interfere with
buffered access
> + retval = adc084s021_adc_conversion(adc, channel);
> + if (retval < 0)
> + return retval;
> +
> + *val = retval;
> + return IIO_VAL_INT;
> +
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +/**
> + * Read enabled ADC channels and push data to the buffer.
> + *
> + * @irq: The interrupt number (not used).
> + * @pollfunc: Pointer to the poll func.
> + */
> +static irqreturn_t adc084s021_trigger_handler(int irq, void *pollfunc)
> +{
> + struct iio_poll_func *pf = pollfunc;
> + struct iio_dev *indio_dev = pf->indio_dev;
> + struct adc084s021 *adc = iio_priv(indio_dev);
> + u8 *data;
> + s64 timestamp;
> + int value, scan_index;
> +
> + data = kzalloc(indio_dev->scan_bytes, GFP_KERNEL);
pre-allocate buffer with maximum size statically; allocation is
potentially expensive; don't forget space for the timestamp and padding...
> + if (!data) {
> + iio_trigger_notify_done(indio_dev->trig);
> + return IRQ_NONE;
> + }
> +
> + timestamp = iio_get_time_ns(indio_dev);
> +
> + for_each_set_bit(scan_index, indio_dev->active_scan_mask,
> + indio_dev->masklength) {
> + const struct iio_chan_spec *channel =
> + &indio_dev->channels[scan_index];
> + value = adc084s021_adc_conversion(adc, channel);
lock is taken and released for each channel, probably want to do it just
once?
> + data[scan_index] = value;
> +
> + /*
> + * Compare read data to previous read. If it differs send
> + * event notification for affected channel.
> + */
> + if (adc->cur_adc_values[scan_index] != (u8)value) {
cur_adc_values is not initialized (probably set to 0);
so on first read, should the notification be sent?
> + adc->cur_adc_values[scan_index] = (u8)value;
> + iio_push_event(indio_dev,
> + IIO_EVENT_CODE(IIO_VOLTAGE, 0,
> + IIO_NO_MOD, IIO_EV_DIR_NONE,
> + IIO_EV_TYPE_CHANGE,
> + channel->channel, 0, 0),
> + timestamp);
> + dev_dbg(&indio_dev->dev,
> + "new value on ch%d: 0x%02X (ts %llu)\n",
> + channel->channel, value, timestamp);
> + }
> + }
> +
> + iio_push_to_buffers_with_timestamp(indio_dev, data, timestamp);
> + iio_trigger_notify_done(indio_dev->trig);
> + kfree(data);
> + return IRQ_HANDLED;
> +}
> +
> +static const struct iio_info adc084s021_info = {
> + .read_raw = adc084s021_read_raw,
> + .driver_module = THIS_MODULE,
> +};
> +
> +/**
> + * Create and register ADC IIO device for SPI.
comment is rather pointless
> + */
> +static int adc084s021_probe(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev;
> + struct adc084s021 *adc;
> + int config = spi_get_device_id(spi)->driver_data;
> + int retval;
ret maybe
> +
> + /* Allocate an Industrial I/O device */
obviously...
> + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
> + if (!indio_dev) {
> + dev_err(&spi->dev, "Failed to allocate IIO device\n");
> + return -ENOMEM;
> + }
> +
> + adc = iio_priv(indio_dev);
> + adc->spi = spi;
> + spi->bits_per_word = ADC_RESOLUTION;
> +
> + /* Update the SPI device with config and connect the iio dev */
> + retval = spi_setup(spi);
> + if (retval) {
> + dev_err(&spi->dev, "Failed to update SPI device\n");
> + return retval;
> + }
> + spi_set_drvdata(spi, indio_dev);
> +
> + /* Initiate the Industrial I/O device */
> + indio_dev->dev.parent = &spi->dev;
> + indio_dev->dev.of_node = spi->dev.of_node;
> + indio_dev->name = spi_get_device_id(spi)->name;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->info = &adc084s021_info;
> + indio_dev->channels = adc084s021_config[config].channels;
> + indio_dev->num_channels = adc084s021_config[config].num_channels;
could do it directly as long there is just one configuration
> +
> + /* Create SPI transfer for channel reads */
> + adc->spi_trans[0].tx_buf = &adc->tx_buf[0];
> + adc->spi_trans[0].len = 2;
> + adc->spi_trans[0].speed_hz = spi->max_speed_hz;
> + adc->spi_trans[0].bits_per_word = spi->bits_per_word;
> + adc->spi_trans[1].rx_buf = &adc->rx_buf[0];
> + adc->spi_trans[1].len = 2;
> + adc->spi_trans[1].speed_hz = spi->max_speed_hz;
> + adc->spi_trans[1].bits_per_word = spi->bits_per_word;
> +
> + /* Setup SPI message for channel reads */
> + spi_message_init(&adc->message);
> + spi_message_add_tail(&adc->spi_trans[0], &adc->message);
> + spi_message_add_tail(&adc->spi_trans[1], &adc->message);
> +
> + adc->reg = devm_regulator_get(&spi->dev, "vref");
> + if (IS_ERR(adc->reg))
> + return PTR_ERR(adc->reg);
> +
> + retval = regulator_enable(adc->reg);
> + if (retval < 0)
> + return retval;
> +
> + mutex_init(&adc->lock);
> +
> + /* Setup triggered buffer with pollfunction */
> + retval = iio_triggered_buffer_setup(indio_dev, NULL,
devm_()
> + adc084s021_trigger_handler, NULL);
> + if (retval) {
> + dev_err(&spi->dev, "Failed to setup triggered buffer\n");
> + goto buffer_setup_failed;
> + }
> +
> + retval = iio_device_register(indio_dev);
> + if (retval) {
> + dev_err(&spi->dev, "Failed to register IIO device\n");
> + goto device_register_failed;
> + }
> +
> + dev_info(&spi->dev, "probed!\n");
no logging please, just outputs clutter
> + return 0;
> +
> +device_register_failed:
> + iio_triggered_buffer_cleanup(indio_dev);
> +buffer_setup_failed:
> + regulator_disable(adc->reg);
> + return retval;
> +}
> +
> +/**
> + * Unregister ADC IIO device for SPI.
> + */
> +static int adc084s021_remove(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev = spi_get_drvdata(spi);
> + struct adc084s021 *adc = iio_priv(indio_dev);
> +
> + iio_device_unregister(indio_dev);
> + iio_triggered_buffer_cleanup(indio_dev);
> + regulator_disable(adc->reg);
> + return 0;
> +}
> +
> +static const struct of_device_id adc084s021_of_match[] = {
> + { .compatible = "ti,adc084s021", },
> + {},
> +};
> +
> +MODULE_DEVICE_TABLE(of, adc084s021_of_match);
> +
> +static const struct spi_device_id adc084s021_id[] = {
> + { MODULE_NAME, 0},
> + {}
> +};
> +
> +MODULE_DEVICE_TABLE(spi, adc084s021_id);
> +
> +static struct spi_driver adc084s021_driver = {
> + .driver = {
> + .name = MODULE_NAME,
> + .of_match_table = of_match_ptr(adc084s021_of_match),
> + },
> + .probe = adc084s021_probe,
> + .remove = adc084s021_remove,
> + .id_table = adc084s021_id,
> +};
> +
> +module_spi_driver(adc084s021_driver);
> +
> +MODULE_AUTHOR("Mårten Lindahl <martenli@xxxxxxxx>");
> +MODULE_DESCRIPTION("Texas Instruments ADC084S021");
> +MODULE_LICENSE("GPL v2");
> +MODULE_VERSION(DRIVER_VERSION);
>
--
Peter Meerwald-Stadler
Mobile: +43 664 24 44 418
