On 09/05/17 16:17, Mårten Lindahl wrote:
On Sun, 2017-05-07 at 15:21 +0100, Jonathan Cameron wrote:
On 03/05/17 13:01, Mårten Lindahl wrote:
From: Mårten Lindahl <martenli@xxxxxxxx>
This adds support for the Texas Instruments ADC084S021 ADC chip.
Signed-off-by: Mårten Lindahl <martenli@xxxxxxxx>
A few more minor bits and pieces.
Jonathan
Hi Jonathan!
I made v4. Please read my comments below. Could there potentially be
garbage in the buffer?
Thanks,
Mårten
---
Changes in v3:
- Removed unnecessary comment about channel specification
- Skipped usage of 'address' in iio_chan_spec config macro
- Mask and shift channel readings only for _read_raw function
- Enable/disable regulator in _read_raw function
- Improved setup of ADC channel readings
- Use SPI config of speed_hz and bits_per_word
- Use devm_iio_triggered_buffer_setup and devm_iio_device_register
- Removed error message for failed devm_iio_device_register
- Removed driver _remove callback function
Changes in v2:
- Removed most #defines in favor of inlines
- Corrected channel macro
- Removed configuration array with only one item
- Updated func adc084s021_adc_conversion to use be16_to_cpu
- Added IIO_CHAN_INFO_SCALE to func adc084s021_read_raw
- Use iio_device_claim_direct_mode in func adc084s021_read_raw
- Removed documentation for standard driver functions
- Changed retval to ret everywhere
- Removed dynamic alloc for data buffer in trigger handler
- Keeping mutex for all iterations in trigger handler
- Removed usage of events in this driver
- Removed info log in probe
- Use spi_message_init_with_transfers for spi message structs
- Use preenable and postdisable functions for regulator
- Inserted blank line before last return in all functions
drivers/iio/adc/Kconfig | 12 ++
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/ti-adc084s021.c | 302 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 315 insertions(+)
create mode 100644 drivers/iio/adc/ti-adc084s021.c
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..f2fb0fa
--- /dev/null
+++ b/drivers/iio/adc/ti-adc084s021.c
@@ -0,0 +1,302 @@
+/**
+ * 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/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/regulator/consumer.h>
+
+#define ADC084S021_DRIVER_NAME "adc084s021"
+
+struct adc084s021 {
+ struct spi_device *spi;
+ struct spi_message message;
+ struct spi_transfer spi_trans;
+ struct regulator *reg;
+ struct mutex lock;
+ /*
+ * DMA (thus cache coherency maintenance) requires the
+ * transfer buffers to live in their own cache lines.
+ */
+ u16 tx_buf[4] ____cacheline_aligned;
+ __be16 rx_buf[5] ____cacheline_aligned; /* First 16-bits are trash */
You only need to do this for tx_buf as then rx_buf will at worst end up
in the same cacheline as it. Fairly implausible that this would cause
issues given they will be read before a transfer and written after.
Doing it twice results in potential waste of say 64 bytes depending on
the cacheline length.
Fixed and verified with pahole in v4.
+};
+
+#define ADC084S021_VOLTAGE_CHANNEL(num) \
+ { \
+ .type = IIO_VOLTAGE, \
+ .channel = (num), \
+ .indexed = 1, \
+ .scan_index = (num), \
+ .scan_type = { \
+ .sign = 'u', \
+ .realbits = 8, \
+ .storagebits = 16, \
+ .shift = 4, \
+ .endianness = IIO_BE, \
They aren't at the moment as you are doing the endian conversion in kernel.
Drop that in the push to buffers path.
Ok, fixed in "push to buffers path" in v4.
+ }, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\
+ }
+
+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 int adc084s021_power_on(struct adc084s021 *adc)
+{
+ int ret;
+
+ ret = regulator_enable(adc->reg);
+ if (ret) {
+ dev_warn(&adc->spi->dev,
+ "Failed to enable supply voltage\n");
+ }
+
+ return ret;
These two little functions do seem a little unnecessary.
A regulator fail should be pretty unlikely so I'd be tempted
to just have the regulator_enable / disable inline instead
of off in these functions.
Fixed in v4.
+}
+
+static int adc084s021_power_off(struct adc084s021 *adc)
+{
+ int ret;
+
+ ret = regulator_disable(adc->reg);
+ if (ret) {
+ dev_warn(&adc->spi->dev,
+ "Failed to disable supply voltage\n");
+ }
+
+ return ret;
+}
+
+/**
+ * Read an ADC channel and return its value.
+ *
+ * @adc: The ADC SPI data.
+ * @data: Buffer for converted data.
+ */
+static int adc084s021_adc_conversion(struct adc084s021 *adc, void *data)
+{
+ int n_words = (adc->spi_trans.len >> 1) - 1; /* Discard first word */
+ int ret, i = 0;
+ u16 *p = data;
+
+ /* Do the transfer */
+ ret = spi_sync(adc->spi, &adc->message);
+ if (ret < 0)
+ return ret;
+
+ for (; i < n_words; i++)
+ *(p + i) = be16_to_cpu(adc->rx_buf[i + 1]);
Should only do the endian conversion in kernel if not
using it for buffered output. In buffered output we can
save a few cycles by leaving it up to userspace.
Ok, fixed in v4.
+
+ return ret;
+}
+
+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 ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ ret = iio_device_claim_direct_mode(indio_dev);
+ if (ret < 0)
+ return ret;
+
+ ret = adc084s021_power_on(adc);
+ if (ret) {
+ iio_device_release_direct_mode(indio_dev);
+ return ret;
+ }
+
+ adc->tx_buf[0] = channel->channel << 3;
+ ret = adc084s021_adc_conversion(adc, val);
+ iio_device_release_direct_mode(indio_dev);
+ adc084s021_power_off(adc);
+ if (ret < 0)
+ return ret;
+
+ *val = (*val >> channel->scan_type.shift) & 0xff;
+
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ ret = adc084s021_power_on(adc);
+ if (ret)
+ return ret;
+
+ ret = regulator_get_voltage(adc->reg);
+ adc084s021_power_off(adc);
+ if (ret < 0)
+ return ret;
+
+ *val = ret / 1000;
+
+ 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_buffer_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);
+ __be16 data[8] = {0}; /* 4 * 16-bit words of data + 8 bytes timestamp */
+
+ mutex_lock(&adc->lock);
+
+ if (adc084s021_adc_conversion(adc, &data) < 0)
+ dev_err(&adc->spi->dev, "Failed to read data\n");
hmm. Not sure I'm keen on pushing garbage to the buffer.
I might fix this up as well... Depends on what else there is ;)
Since the __be16 data[8] array is initialized to 0, and the
adc084s021_adc_conversion function error returns before any data has
been copied to the array it should always contain either zeroes or valid
data as I see it. Would it be wrong to push zeroes?
Yes from the point of view that userspace might think it was actual
data. Not critical in an error path though I suppose.
+
+ iio_push_to_buffers_with_timestamp(indio_dev, data,
+ iio_get_time_ns(indio_dev));
+ mutex_unlock(&adc->lock);
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
+
+static int adc084s021_buffer_preenable(struct iio_dev *indio_dev)
+{
+ struct adc084s021 *adc = iio_priv(indio_dev);
+ int scan_index;
+ int i = 0;
+
+ 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];
+ adc->tx_buf[i++] = channel->channel << 3;
+ }
+ adc->spi_trans.len = 2 + (i * sizeof(__be16)); /* Trash + channels */
+
+ return adc084s021_power_on(adc);
+}
+
+static int adc084s021_buffer_postdisable(struct iio_dev *indio_dev)
+{
+ struct adc084s021 *adc = iio_priv(indio_dev);
+
+ adc->spi_trans.len = 4; /* Trash + single channel */
+
+ return adc084s021_power_off(adc);
+}
+
+static const struct iio_info adc084s021_info = {
+ .read_raw = adc084s021_read_raw,
+ .driver_module = THIS_MODULE,
+};
+
+static const struct iio_buffer_setup_ops adc084s021_buffer_setup_ops = {
+ .preenable = adc084s021_buffer_preenable,
+ .postenable = iio_triggered_buffer_postenable,
+ .predisable = iio_triggered_buffer_predisable,
+ .postdisable = adc084s021_buffer_postdisable,
+};
+
+static int adc084s021_probe(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev;
+ struct adc084s021 *adc;
+ int ret;
+
+ 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;
+
+ /* Connect the SPI device and the iio dev */
+ 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_channels;
+ indio_dev->num_channels = ARRAY_SIZE(adc084s021_channels);
+
+ /* Create SPI transfer for channel reads */
+ adc->spi_trans.tx_buf = adc->tx_buf;
+ adc->spi_trans.rx_buf = adc->rx_buf;
+ adc->spi_trans.len = 4; /* Trash + single channel */
+ spi_message_init_with_transfers(&adc->message, &adc->spi_trans, 1);
+
+ adc->reg = devm_regulator_get(&spi->dev, "vref");
+ if (IS_ERR(adc->reg))
+ return PTR_ERR(adc->reg);
+
+ mutex_init(&adc->lock);
+
+ /* Setup triggered buffer with pollfunction */
+ ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
+ adc084s021_buffer_trigger_handler,
+ &adc084s021_buffer_setup_ops);
+ if (ret) {
+ dev_err(&spi->dev, "Failed to setup triggered buffer\n");
+ return ret;
+ }
+
+ ret = devm_iio_device_register(&spi->dev, indio_dev);
+
+ return ret;
return devm_iio_deivce_register(...
Fixed in v4.
If this all there is I'll fix it up.
Ok, so I'll send no more patches after v4 then?
+}
+
+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[] = {
+ { ADC084S021_DRIVER_NAME, 0},
+ {}
+};
+MODULE_DEVICE_TABLE(spi, adc084s021_id);
+
+static struct spi_driver adc084s021_driver = {
+ .driver = {
+ .name = ADC084S021_DRIVER_NAME,
+ .of_match_table = of_match_ptr(adc084s021_of_match),
+ },
+ .probe = adc084s021_probe,
+ .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("1.0");
--
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