Up to now, the IIO subsystem has only supported a single scan type per
channel. This scan type determines the binary format of the data in the
buffer when doing buffered reads.
For simple devices, there is only one scan type and all is well. But
for more complex devices, there may be multiple scan types. For example,
ADCs with a resolution boost feature that adds more bits to the raw
sample data. Traditionally, for slow devices, we've just always used the
highest resolution mode, but for high performance ADCs, this may not be
always practical. Manipulating data after every read can hurt performance
and in the case of hardware buffers, it may not be possible to change the
format of the data in the buffer at all. There are also ADCs where
enabling the higher resolution can only be done if oversampling is also
enabled which may not be desireable.
To allow for more flexibility, we would like to add support for multiple
scan types per channel.
To avoid having to touch every driver, we implemented this in a way that
preserves the existing scan_type field. See the "iio: add support for
multiple scan types per channel" the details. The first couple of patches
are just preparation for this.
[1]: https://lore.kernel.org/linux-iio/CAMknhBHOXaff__QyU-wFSNNENvs23vDX5n_ddH-Dw3s6-sQ9sg@mail.gmail.com/
---
Changes in v3:
* Changed return type of get_current_scan_type callback to int.
* Brought back updated ad7380 patches.
* Link to v2: https://lore.kernel.org/r/20240524-iio-add-support-for-multiple-scan-types-v2-0-a6c328fdfab7@baylibre.com
Changes in v2:
* Use union for scan_type and scan_type_ext.
* Dropped ad7380 patch - those changed will be squashed into the next
revision of the series adding the driver for ad7380.
* Temporary updated ad7380 patch for reference: https://github.com/dlech/linux/commit/64be3de241e73b43c5a5daa44b6b97f35f0743bf
* Link to v1: https://lore.kernel.org/r/20240507-iio-add-support-for-multiple-scan-types-v1-0-95ac33ee51e9@baylibre.com
---
David Lechner (4):
iio: introduce struct iio_scan_type
iio: buffer: use struct iio_scan_type to simplify code
iio: add support for multiple scan types per channel
iio: adc: ad7380: use spi_optimize_message()
Julien Stephan (1):
iio: adc: ad7380: add oversampling support
drivers/iio/adc/ad7380.c | 335 +++++++++++++++++++++++++++++++-------
drivers/iio/industrialio-buffer.c | 129 +++++++++++----
include/linux/iio/iio.h | 94 ++++++++---
3 files changed, 450 insertions(+), 108 deletions(-)
---
base-commit: b4bfc5f52090336f5f5b65bbdac394ac1001952d
change-id: 20240507-iio-add-support-for-multiple-scan-types-f4dbcf4c2cb8
By using struct iio_scan_type, we can simplify the code by removing
lots of duplicate pointer dereferences. This make the code a bit easier
to read.
This also prepares for a future where channels may have more than one
scan_type.
Signed-off-by: David Lechner <[email protected]>
---
v3 changes: none
v2 changes:
* fixed spelling of dereferences in commit message
---
drivers/iio/industrialio-buffer.c | 48 +++++++++++++++++++++++----------------
1 file changed, 28 insertions(+), 20 deletions(-)
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index cec58a604d73..08103a9e77f7 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -366,7 +366,8 @@ static ssize_t iio_show_fixed_type(struct device *dev,
char *buf)
{
struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
- u8 type = this_attr->c->scan_type.endianness;
+ const struct iio_scan_type *scan_type = &this_attr->c->scan_type;
+ u8 type = scan_type->endianness;
if (type == IIO_CPU) {
#ifdef __LITTLE_ENDIAN
@@ -375,21 +376,21 @@ static ssize_t iio_show_fixed_type(struct device *dev,
type = IIO_BE;
#endif
}
- if (this_attr->c->scan_type.repeat > 1)
+ if (scan_type->repeat > 1)
return sysfs_emit(buf, "%s:%c%d/%dX%d>>%u\n",
iio_endian_prefix[type],
- this_attr->c->scan_type.sign,
- this_attr->c->scan_type.realbits,
- this_attr->c->scan_type.storagebits,
- this_attr->c->scan_type.repeat,
- this_attr->c->scan_type.shift);
+ scan_type->sign,
+ scan_type->realbits,
+ scan_type->storagebits,
+ scan_type->repeat,
+ scan_type->shift);
else
return sysfs_emit(buf, "%s:%c%d/%d>>%u\n",
iio_endian_prefix[type],
- this_attr->c->scan_type.sign,
- this_attr->c->scan_type.realbits,
- this_attr->c->scan_type.storagebits,
- this_attr->c->scan_type.shift);
+ scan_type->sign,
+ scan_type->realbits,
+ scan_type->storagebits,
+ scan_type->shift);
}
static ssize_t iio_scan_el_show(struct device *dev,
@@ -694,12 +695,16 @@ static unsigned int iio_storage_bytes_for_si(struct iio_dev *indio_dev,
unsigned int scan_index)
{
const struct iio_chan_spec *ch;
+ const struct iio_scan_type *scan_type;
unsigned int bytes;
ch = iio_find_channel_from_si(indio_dev, scan_index);
- bytes = ch->scan_type.storagebits / 8;
- if (ch->scan_type.repeat > 1)
- bytes *= ch->scan_type.repeat;
+ scan_type = &ch->scan_type;
+ bytes = scan_type->storagebits / 8;
+
+ if (scan_type->repeat > 1)
+ bytes *= scan_type->repeat;
+
return bytes;
}
@@ -1616,18 +1621,21 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
if (channels) {
/* new magic */
for (i = 0; i < indio_dev->num_channels; i++) {
+ const struct iio_scan_type *scan_type;
+
if (channels[i].scan_index < 0)
continue;
+ scan_type = &channels[i].scan_type;
+
/* Verify that sample bits fit into storage */
- if (channels[i].scan_type.storagebits <
- channels[i].scan_type.realbits +
- channels[i].scan_type.shift) {
+ if (scan_type->storagebits <
+ scan_type->realbits + scan_type->shift) {
dev_err(&indio_dev->dev,
"Channel %d storagebits (%d) < shifted realbits (%d + %d)\n",
- i, channels[i].scan_type.storagebits,
- channels[i].scan_type.realbits,
- channels[i].scan_type.shift);
+ i, scan_type->storagebits,
+ scan_type->realbits,
+ scan_type->shift);
ret = -EINVAL;
goto error_cleanup_dynamic;
}
--
2.45.1
This adds new fields to the iio_channel structure to support multiple
scan types per channel. This is useful for devices that support multiple
resolution modes or other modes that require different data formats of
the raw data.
To make use of this, drivers need to implement the new callback
get_current_scan_type() to resolve the scan type for a given channel
based on the current state of the driver. There is a new scan_type_ext
field in the iio_channel structure that should be used to store the
scan types for any channel that has more than one. There is also a new
flag has_ext_scan_type that acts as a type discriminator for the
scan_type/ext_scan_type union. A union is used so that we don't grow
the size of the iio_channel structure and also makes it clear that
scan_type and ext_scan_type are mutually exclusive.
The buffer code is the only code in the IIO core code that is using the
scan_type field. This patch updates the buffer code to use the new
iio_channel_validate_scan_type() function to ensure it is returning the
correct scan type for the current state of the device when reading the
sysfs attributes. The buffer validation code is also update to validate
any additional scan types that are set in the scan_type_ext field. Part
of that code is refactored to a new function to avoid duplication.
Some userspace tools may need to be updated to re-read the scan type
after writing any other attribute. During testing, we noticed that we
had to restart iiod to get it to re-read the scan type after enabling
oversampling on the ad7380 driver.
Signed-off-by: David Lechner <[email protected]>
---
v3 changes:
* change return type of get_current_scan_type callback to int
* add error checks since iio_get_current_scan_type() can can now return
an error
v2 changes:
* use union for scan_type and ext_scan_type/num_ext_scan_types
* add has_ext_scan_type flag for type discrimination
* add extra validation check for get_current_scan_type when
has_ext_scan_type is set
---
drivers/iio/industrialio-buffer.c | 101 ++++++++++++++++++++++++++++++--------
include/linux/iio/iio.h | 55 ++++++++++++++++++++-
2 files changed, 133 insertions(+), 23 deletions(-)
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 08103a9e77f7..0138b21b244f 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -365,9 +365,16 @@ static ssize_t iio_show_fixed_type(struct device *dev,
struct device_attribute *attr,
char *buf)
{
+ struct iio_dev *indio_dev = dev_to_iio_dev(dev);
struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
- const struct iio_scan_type *scan_type = &this_attr->c->scan_type;
- u8 type = scan_type->endianness;
+ const struct iio_scan_type *scan_type;
+ u8 type;
+
+ scan_type = iio_get_current_scan_type(indio_dev, this_attr->c);
+ if (IS_ERR(scan_type))
+ return PTR_ERR(scan_type);
+
+ type = scan_type->endianness;
if (type == IIO_CPU) {
#ifdef __LITTLE_ENDIAN
@@ -691,15 +698,18 @@ static ssize_t enable_show(struct device *dev, struct device_attribute *attr,
return sysfs_emit(buf, "%d\n", iio_buffer_is_active(buffer));
}
-static unsigned int iio_storage_bytes_for_si(struct iio_dev *indio_dev,
- unsigned int scan_index)
+static int iio_storage_bytes_for_si(struct iio_dev *indio_dev,
+ unsigned int scan_index)
{
const struct iio_chan_spec *ch;
const struct iio_scan_type *scan_type;
unsigned int bytes;
ch = iio_find_channel_from_si(indio_dev, scan_index);
- scan_type = &ch->scan_type;
+ scan_type = iio_get_current_scan_type(indio_dev, ch);
+ if (IS_ERR(scan_type))
+ return PTR_ERR(scan_type);
+
bytes = scan_type->storagebits / 8;
if (scan_type->repeat > 1)
@@ -708,7 +718,7 @@ static unsigned int iio_storage_bytes_for_si(struct iio_dev *indio_dev,
return bytes;
}
-static unsigned int iio_storage_bytes_for_timestamp(struct iio_dev *indio_dev)
+static int iio_storage_bytes_for_timestamp(struct iio_dev *indio_dev)
{
struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
@@ -726,6 +736,9 @@ static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
for_each_set_bit(i, mask,
indio_dev->masklength) {
length = iio_storage_bytes_for_si(indio_dev, i);
+ if (length < 0)
+ return length;
+
bytes = ALIGN(bytes, length);
bytes += length;
largest = max(largest, length);
@@ -733,6 +746,9 @@ static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
if (timestamp) {
length = iio_storage_bytes_for_timestamp(indio_dev);
+ if (length < 0)
+ return length;
+
bytes = ALIGN(bytes, length);
bytes += length;
largest = max(largest, length);
@@ -1012,14 +1028,22 @@ static int iio_buffer_update_demux(struct iio_dev *indio_dev,
indio_dev->masklength,
in_ind + 1);
while (in_ind != out_ind) {
- length = iio_storage_bytes_for_si(indio_dev, in_ind);
+ ret = iio_storage_bytes_for_si(indio_dev, in_ind);
+ if (ret < 0)
+ goto error_clear_mux_table;
+
+ length = ret;
/* Make sure we are aligned */
in_loc = roundup(in_loc, length) + length;
in_ind = find_next_bit(indio_dev->active_scan_mask,
indio_dev->masklength,
in_ind + 1);
}
- length = iio_storage_bytes_for_si(indio_dev, in_ind);
+ ret = iio_storage_bytes_for_si(indio_dev, in_ind);
+ if (ret < 0)
+ goto error_clear_mux_table;
+
+ length = ret;
out_loc = roundup(out_loc, length);
in_loc = roundup(in_loc, length);
ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
@@ -1030,7 +1054,11 @@ static int iio_buffer_update_demux(struct iio_dev *indio_dev,
}
/* Relies on scan_timestamp being last */
if (buffer->scan_timestamp) {
- length = iio_storage_bytes_for_timestamp(indio_dev);
+ ret = iio_storage_bytes_for_timestamp(indio_dev);
+ if (ret < 0)
+ goto error_clear_mux_table;
+
+ length = ret;
out_loc = roundup(out_loc, length);
in_loc = roundup(in_loc, length);
ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
@@ -1597,6 +1625,22 @@ static long iio_device_buffer_ioctl(struct iio_dev *indio_dev, struct file *filp
}
}
+static int iio_channel_validate_scan_type(struct device *dev, int ch,
+ const struct iio_scan_type *scan_type)
+{
+ /* Verify that sample bits fit into storage */
+ if (scan_type->storagebits < scan_type->realbits + scan_type->shift) {
+ dev_err(dev,
+ "Channel %d storagebits (%d) < shifted realbits (%d + %d)\n",
+ ch, scan_type->storagebits,
+ scan_type->realbits,
+ scan_type->shift);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
struct iio_dev *indio_dev,
int index)
@@ -1626,18 +1670,33 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
if (channels[i].scan_index < 0)
continue;
- scan_type = &channels[i].scan_type;
-
- /* Verify that sample bits fit into storage */
- if (scan_type->storagebits <
- scan_type->realbits + scan_type->shift) {
- dev_err(&indio_dev->dev,
- "Channel %d storagebits (%d) < shifted realbits (%d + %d)\n",
- i, scan_type->storagebits,
- scan_type->realbits,
- scan_type->shift);
- ret = -EINVAL;
- goto error_cleanup_dynamic;
+ if (channels[i].has_ext_scan_type) {
+ int j;
+
+ /*
+ * get_current_scan_type is required when using
+ * extended scan types.
+ */
+ if (!indio_dev->info->get_current_scan_type) {
+ ret = -EINVAL;
+ goto error_cleanup_dynamic;
+ }
+
+ for (j = 0; j < channels[i].num_ext_scan_type; j++) {
+ scan_type = &channels[i].ext_scan_type[j];
+
+ ret = iio_channel_validate_scan_type(
+ &indio_dev->dev, i, scan_type);
+ if (ret)
+ goto error_cleanup_dynamic;
+ }
+ } else {
+ scan_type = &channels[i].scan_type;
+
+ ret = iio_channel_validate_scan_type(
+ &indio_dev->dev, i, scan_type);
+ if (ret)
+ goto error_cleanup_dynamic;
}
ret = iio_buffer_add_channel_sysfs(indio_dev, buffer,
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index 19de573a944a..894309294182 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -204,7 +204,13 @@ struct iio_scan_type {
* @address: Driver specific identifier.
* @scan_index: Monotonic index to give ordering in scans when read
* from a buffer.
- * @scan_type: struct describing the scan type
+ * @scan_type: struct describing the scan type - mutually exclusive
+ * with ext_scan_type.
+ * @ext_scan_type: Used in rare cases where there is more than one scan
+ * format for a channel. When this is used, the flag
+ * has_ext_scan_type must be set and the driver must
+ * implement get_current_scan_type in struct iio_info.
+ * @num_ext_scan_type: Number of elements in ext_scan_type.
* @info_mask_separate: What information is to be exported that is specific to
* this channel.
* @info_mask_separate_available: What availability information is to be
@@ -248,6 +254,7 @@ struct iio_scan_type {
* attributes but not for event codes.
* @output: Channel is output.
* @differential: Channel is differential.
+ * @has_ext_scan_type: True if ext_scan_type is used instead of scan_type.
*/
struct iio_chan_spec {
enum iio_chan_type type;
@@ -255,7 +262,13 @@ struct iio_chan_spec {
int channel2;
unsigned long address;
int scan_index;
- struct iio_scan_type scan_type;
+ union {
+ struct iio_scan_type scan_type;
+ struct {
+ const struct iio_scan_type *ext_scan_type;
+ unsigned int num_ext_scan_type;
+ };
+ };
long info_mask_separate;
long info_mask_separate_available;
long info_mask_shared_by_type;
@@ -273,6 +286,7 @@ struct iio_chan_spec {
unsigned indexed:1;
unsigned output:1;
unsigned differential:1;
+ unsigned has_ext_scan_type:1;
};
@@ -435,6 +449,9 @@ struct iio_trigger; /* forward declaration */
* for better event identification.
* @validate_trigger: function to validate the trigger when the
* current trigger gets changed.
+ * @get_current_scan_type: must be implemented by drivers that use ext_scan_type
+ * in the channel spec to return the index of the currently
+ * active ext_scan type for a channel.
* @update_scan_mode: function to configure device and scan buffer when
* channels have changed
* @debugfs_reg_access: function to read or write register value of device
@@ -519,6 +536,8 @@ struct iio_info {
int (*validate_trigger)(struct iio_dev *indio_dev,
struct iio_trigger *trig);
+ int (*get_current_scan_type)(const struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan);
int (*update_scan_mode)(struct iio_dev *indio_dev,
const unsigned long *scan_mask);
int (*debugfs_reg_access)(struct iio_dev *indio_dev,
@@ -804,6 +823,38 @@ static inline bool iio_read_acpi_mount_matrix(struct device *dev,
}
#endif
+/**
+ * iio_get_current_scan_type - Get the current scan type for a channel
+ * @indio_dev: the IIO device to get the scan type for
+ * @chan: the channel to get the scan type for
+ *
+ * Most devices only have one scan type per channel and can just access it
+ * directly without calling this function. Core IIO code and drivers that
+ * implement ext_scan_type in the channel spec should use this function to
+ * get the current scan type for a channel.
+ *
+ * Returns: the current scan type for the channel or error.
+ */
+static inline const struct iio_scan_type
+*iio_get_current_scan_type(const struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan)
+{
+ int ret;
+
+ if (chan->has_ext_scan_type) {
+ ret = indio_dev->info->get_current_scan_type(indio_dev, chan);
+ if (ret < 0)
+ return ERR_PTR(ret);
+
+ if (ret >= chan->num_ext_scan_type)
+ return ERR_PTR(-EINVAL);
+
+ return &chan->ext_scan_type[ret];
+ }
+
+ return &chan->scan_type;
+}
+
ssize_t iio_format_value(char *buf, unsigned int type, int size, int *vals);
int iio_str_to_fixpoint(const char *str, int fract_mult, int *integer,
--
2.45.1
This changes the AD7380 to use spi_optimize_message() to optimize
buffered reads.
This changes both direct reads and buffered reads to use the same
spi_message. This has some (welcome) side effects. The first is that
in buffered reads, the timestamp will now correspond to the same sample
rather than the previous sample. The second is that direct reads now
use the same SPI bus speed as buffered reads.
This reduces CPU usage of the IRQ thread from around 25% to around 20%
when sampling at 10 kHz on a ZedBoard.
Signed-off-by: David Lechner <[email protected]>
---
v3 changes:
* New patch for this series
* A similar patch was sent at [1].
[1]: https://lore.kernel.org/linux-iio/20240219-mainline-spi-precook-message-v2-5-4a762c6701b9@baylibre.com/
---
drivers/iio/adc/ad7380.c | 70 ++++++++++++++++++++++++++----------------------
1 file changed, 38 insertions(+), 32 deletions(-)
diff --git a/drivers/iio/adc/ad7380.c b/drivers/iio/adc/ad7380.c
index 6b0b1b0be363..006496807de9 100644
--- a/drivers/iio/adc/ad7380.c
+++ b/drivers/iio/adc/ad7380.c
@@ -232,6 +232,9 @@ struct ad7380_state {
struct regmap *regmap;
unsigned int vref_mv;
unsigned int vcm_mv[MAX_NUM_CHANNELS];
+ /* xfers, message an buffer for reading sample data */
+ struct spi_transfer xfer[2];
+ struct spi_message msg;
/*
* DMA (thus cache coherency maintenance) requires the
* transfer buffers to live in their own cache lines.
@@ -331,15 +334,9 @@ static irqreturn_t ad7380_trigger_handler(int irq, void *p)
struct iio_poll_func *pf = p;
struct iio_dev *indio_dev = pf->indio_dev;
struct ad7380_state *st = iio_priv(indio_dev);
- struct spi_transfer xfer = {
- .bits_per_word = st->chip_info->channels[0].scan_type.realbits,
- .len = (st->chip_info->num_channels - 1) *
- BITS_TO_BYTES(st->chip_info->channels->scan_type.storagebits),
- .rx_buf = st->scan_data.raw,
- };
int ret;
- ret = spi_sync_transfer(st->spi, &xfer, 1);
+ ret = spi_sync(st->spi, &st->msg);
if (ret)
goto out;
@@ -355,33 +352,9 @@ static irqreturn_t ad7380_trigger_handler(int irq, void *p)
static int ad7380_read_direct(struct ad7380_state *st,
struct iio_chan_spec const *chan, int *val)
{
- struct spi_transfer xfers[] = {
- /* toggle CS (no data xfer) to trigger a conversion */
- {
- .speed_hz = AD7380_REG_WR_SPEED_HZ,
- .bits_per_word = chan->scan_type.realbits,
- .delay = {
- .value = T_CONVERT_NS,
- .unit = SPI_DELAY_UNIT_NSECS,
- },
- .cs_change = 1,
- .cs_change_delay = {
- .value = st->chip_info->timing_specs->t_csh_ns,
- .unit = SPI_DELAY_UNIT_NSECS,
- },
- },
- /* then read all channels */
- {
- .speed_hz = AD7380_REG_WR_SPEED_HZ,
- .bits_per_word = chan->scan_type.realbits,
- .rx_buf = st->scan_data.raw,
- .len = (st->chip_info->num_channels - 1) *
- ((chan->scan_type.storagebits > 16) ? 4 : 2),
- },
- };
int ret;
- ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
+ ret = spi_sync(st->spi, &st->msg);
if (ret < 0)
return ret;
@@ -464,6 +437,11 @@ static void ad7380_regulator_disable(void *p)
regulator_disable(p);
}
+static void ad7380_unoptimize_msg(void *msg)
+{
+ spi_unoptimize_message(msg);
+}
+
static int ad7380_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
@@ -552,6 +530,34 @@ static int ad7380_probe(struct spi_device *spi)
return dev_err_probe(&spi->dev, PTR_ERR(st->regmap),
"failed to allocate register map\n");
+ /*
+ * Setting up a low latency read for getting sample data. Used for both
+ * direct read an triggered buffer.
+ */
+
+ /* toggle CS (no data xfer) to trigger a conversion */
+ st->xfer[0].delay.value = T_CONVERT_NS;
+ st->xfer[0].delay.unit = SPI_DELAY_UNIT_NSECS;
+ st->xfer[0].cs_change = 1;
+ st->xfer[0].cs_change_delay.value = st->chip_info->timing_specs->t_csh_ns;
+ st->xfer[0].cs_change_delay.unit = SPI_DELAY_UNIT_NSECS;
+
+ /* then do a second xfer to read the data */
+ st->xfer[1].bits_per_word = st->chip_info->channels[0].scan_type.realbits;
+ st->xfer[1].rx_buf = st->scan_data.raw;
+ st->xfer[1].len = BITS_TO_BYTES(st->chip_info->channels[0].scan_type.storagebits)
+ * (st->chip_info->num_channels - 1);
+
+ spi_message_init_with_transfers(&st->msg, st->xfer, ARRAY_SIZE(st->xfer));
+
+ ret = spi_optimize_message(st->spi, &st->msg);
+ if (ret)
+ return ret;
+
+ ret = devm_add_action_or_reset(&spi->dev, ad7380_unoptimize_msg, &st->msg);
+ if (ret)
+ return ret;
+
indio_dev->channels = st->chip_info->channels;
indio_dev->num_channels = st->chip_info->num_channels;
indio_dev->name = st->chip_info->name;
--
2.45.1
From: Julien Stephan <[email protected]>
ad7380x(-4) parts are able to do oversampling to increase accuracy.
This chips supports a normal oversampling mode and a rolling mode and
also allows enabling and disabling extra resolution bits when
oversampling is enabled.
We have intentionally left out the rolling mode for now as there is not
a compelling use case for it. User can process a captured data buffer
to get the same effect.
We are also currently not supporting changing the oversampling mode
independently of the resolution bits. The resolution boost feature
can only be enabled when oversampling is enabled and oversampling is
not as useful without the resolution boost. So for now we consider the
features tightly coupled. When oversampling is enabled, the resolution
boost is enabled and when oversampling is disabled, the resolution
boost is disabled.
Since the resolution boost feature causes 16-bit chips to now have
18-bit data which means the storagebits has to change from 16 to 32
bits, we use the new ext_scan_type feature to allow changing the
scan_type at runtime based on if the resolution boost is enabled or
not.
SPI message optimization has to be moved since now some of the xfer
parameters change based on the resolution boost mode.
A few neighboring comments are also fixed up while we are touching this
code.
Signed-off-by: Julien Stephan <[email protected]>
Co-developed-by: David Lechner <[email protected]>
Signed-off-by: David Lechner <[email protected]>
---
v3 changes:
* This is a combination/rework of [1] from v1 of this series plus [2]
and [3] from v6 of the ad7380 introductory series.
* Fixed comment lengths to ~80 characters.
* Renamed osr_check function.
* Resolution boost is no longer a separate feature from oversampling.
* Convert scan_data to u8[] and use ALIGN to ensure correct size.
* Reworked ext_scan_type to accommodate other revisions from this series.
[1]: https://lore.kernel.org/linux-iio/20240507-iio-add-support-for-multiple-scan-types-v1-4-95ac33ee51e9@baylibre.com/
[2]: https://lore.kernel.org/linux-iio/[email protected]/
[3]: https://lore.kernel.org/linux-iio/20240501-adding-new-ad738x-driver-v6-10-3c0741154728@baylibre.com/
---
drivers/iio/adc/ad7380.c | 305 ++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 260 insertions(+), 45 deletions(-)
diff --git a/drivers/iio/adc/ad7380.c b/drivers/iio/adc/ad7380.c
index 006496807de9..2f9f871a0ae0 100644
--- a/drivers/iio/adc/ad7380.c
+++ b/drivers/iio/adc/ad7380.c
@@ -13,6 +13,7 @@
* ad7383/4-4 : https://www.analog.com/media/en/technical-documentation/data-sheets/ad7383-4-ad7384-4.pdf
*/
+#include <linux/align.h>
#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/cleanup.h>
@@ -68,6 +69,9 @@
#define AD7380_ALERT_HIGH_TH GENMASK(11, 0)
#define T_CONVERT_NS 190 /* conversion time */
+#define T_CONVERT_0_NS 10 /* 1st conversion start time (oversampling) */
+#define T_CONVERT_X_NS 500 /* xth conversion start time (oversampling) */
+
struct ad7380_timing_specs {
const unsigned int t_csh_ns; /* CS minimum high time */
};
@@ -82,22 +86,59 @@ struct ad7380_chip_info {
const struct ad7380_timing_specs *timing_specs;
};
+enum {
+ AD7380_SCAN_TYPE_NORMAL,
+ AD7380_SCAN_TYPE_RESOLUTION_BOOST,
+};
+
+/* Extended scan types for 14-bit chips. */
+static const struct iio_scan_type ad7380_scan_type_14[] = {
+ [AD7380_SCAN_TYPE_NORMAL] = {
+ .sign = 's',
+ .realbits = 14,
+ .storagebits = 16,
+ .endianness = IIO_CPU
+ },
+ [AD7380_SCAN_TYPE_RESOLUTION_BOOST] = {
+ .sign = 's',
+ .realbits = 16,
+ .storagebits = 16,
+ .endianness = IIO_CPU
+ },
+};
+
+/* Extended scan types for 16-bit chips. */
+static const struct iio_scan_type ad7380_scan_type_16[] = {
+ [AD7380_SCAN_TYPE_NORMAL] = {
+ .sign = 's',
+ .realbits = 16,
+ .storagebits = 16,
+ .endianness = IIO_CPU
+ },
+ [AD7380_SCAN_TYPE_RESOLUTION_BOOST] = {
+ .sign = 's',
+ .realbits = 18,
+ .storagebits = 32,
+ .endianness = IIO_CPU
+ },
+};
+
#define AD7380_CHANNEL(index, bits, diff) { \
.type = IIO_VOLTAGE, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
((diff) ? 0 : BIT(IIO_CHAN_INFO_OFFSET)), \
- .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
+ BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
+ .info_mask_shared_by_type_available = \
+ BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
.indexed = 1, \
.differential = (diff), \
.channel = (diff) ? (2 * (index)) : (index), \
.channel2 = (diff) ? (2 * (index) + 1) : 0, \
.scan_index = (index), \
- .scan_type = { \
- .sign = 's', \
- .realbits = (bits), \
- .storagebits = 16, \
- .endianness = IIO_CPU, \
- }, \
+ .has_ext_scan_type = 1, \
+ .ext_scan_type = ad7380_scan_type_##bits, \
+ .num_ext_scan_type = ARRAY_SIZE(ad7380_scan_type_##bits),\
}
#define DEFINE_AD7380_2_CHANNEL(name, bits, diff) \
@@ -154,6 +195,15 @@ static const struct ad7380_timing_specs ad7380_4_timing = {
.t_csh_ns = 20,
};
+/*
+ * Available oversampling ratios. The indices correspond with the bit value
+ * expected by the chip. The available ratios depend on the averaging mode,
+ * only normal averaging is supported for now.
+ */
+static const int ad7380_oversampling_ratios[] = {
+ 1, 2, 4, 8, 16, 32,
+};
+
static const struct ad7380_chip_info ad7380_chip_info = {
.name = "ad7380",
.channels = ad7380_channels,
@@ -230,23 +280,23 @@ struct ad7380_state {
const struct ad7380_chip_info *chip_info;
struct spi_device *spi;
struct regmap *regmap;
+ unsigned int oversampling_ratio;
+ bool resolution_boost_enabled;
unsigned int vref_mv;
unsigned int vcm_mv[MAX_NUM_CHANNELS];
/* xfers, message an buffer for reading sample data */
struct spi_transfer xfer[2];
struct spi_message msg;
/*
- * DMA (thus cache coherency maintenance) requires the
- * transfer buffers to live in their own cache lines.
- * Make the buffer large enough for MAX_NUM_CHANNELS 16-bit samples and one 64-bit
- * aligned 64 bit timestamp.
- * As MAX_NUM_CHANNELS is 4 the layout of the structure is the same for all parts
+ * DMA (thus cache coherency maintenance) requires the transfer buffers
+ * to live in their own cache lines.
+ *
+ * Make the buffer large enough for MAX_NUM_CHANNELS 32-bit samples and
+ * one 64-bit aligned 64-bit timestamp.
*/
- struct {
- u16 raw[MAX_NUM_CHANNELS];
-
- s64 ts __aligned(8);
- } scan_data __aligned(IIO_DMA_MINALIGN);
+ u8 scan_data[ALIGN(MAX_NUM_CHANNELS * sizeof(u32), sizeof(s64))
+ + sizeof(s64)] __aligned(IIO_DMA_MINALIGN);
+ /* buffers for reading/writing registers */
u16 tx;
u16 rx;
};
@@ -329,6 +379,69 @@ static int ad7380_debugfs_reg_access(struct iio_dev *indio_dev, u32 reg,
unreachable();
}
+/**
+ * ad7380_update_xfers - update the SPI transfers base on the current scan type
+ * @indio_dev: IIO device structure
+ * @chan: IIO channel
+ */
+static void ad7380_update_xfers(struct ad7380_state *st,
+ const struct iio_scan_type *scan_type)
+{
+ /*
+ * First xfer only triggers conversion and has to be long enough for
+ * all conversions to complete, which can be multiple conversion in the
+ * case of oversampling. Technically T_CONVERT_X_NS is lower for some
+ * chips, but we use the maximum value for simplicity for now.
+ */
+ if (st->oversampling_ratio > 1)
+ st->xfer[0].delay.value = T_CONVERT_0_NS + T_CONVERT_X_NS *
+ (st->oversampling_ratio - 1);
+ else
+ st->xfer[0].delay.value = T_CONVERT_NS;
+
+ st->xfer[0].delay.unit = SPI_DELAY_UNIT_NSECS;
+
+ /*
+ * Second xfer reads all channels. Data size depends on if resolution
+ * boost is enabled or not.
+ */
+ st->xfer[1].bits_per_word = scan_type->realbits;
+ st->xfer[1].len = BITS_TO_BYTES(scan_type->storagebits) *
+ (st->chip_info->num_channels - 1);
+}
+
+static int ad7380_triggered_buffer_preenable(struct iio_dev *indio_dev)
+{
+ struct ad7380_state *st = iio_priv(indio_dev);
+ const struct iio_scan_type *scan_type;
+
+ /*
+ * Currently, we always read all channels at the same time. The scan_type
+ * is the same for all channels, so we just pass the first channel.
+ */
+ scan_type = iio_get_current_scan_type(indio_dev, &indio_dev->channels[0]);
+ if (IS_ERR(scan_type))
+ return PTR_ERR(scan_type);
+
+ ad7380_update_xfers(st, scan_type);
+
+ return spi_optimize_message(st->spi, &st->msg);
+}
+
+static int ad7380_triggered_buffer_postdisable(struct iio_dev *indio_dev)
+{
+ struct ad7380_state *st = iio_priv(indio_dev);
+
+ spi_unoptimize_message(&st->msg);
+
+ return 0;
+}
+
+static const struct iio_buffer_setup_ops ad7380_buffer_setup_ops = {
+ .preenable = ad7380_triggered_buffer_preenable,
+ .postdisable = ad7380_triggered_buffer_postdisable,
+};
+
static irqreturn_t ad7380_trigger_handler(int irq, void *p)
{
struct iio_poll_func *pf = p;
@@ -349,17 +462,23 @@ static irqreturn_t ad7380_trigger_handler(int irq, void *p)
return IRQ_HANDLED;
}
-static int ad7380_read_direct(struct ad7380_state *st,
- struct iio_chan_spec const *chan, int *val)
+static int ad7380_read_direct(struct ad7380_state *st, unsigned int scan_index,
+ const struct iio_scan_type *scan_type, int *val)
{
int ret;
+ ad7380_update_xfers(st, scan_type);
+
ret = spi_sync(st->spi, &st->msg);
if (ret < 0)
return ret;
- *val = sign_extend32(st->scan_data.raw[chan->scan_index],
- chan->scan_type.realbits - 1);
+ if (scan_type->storagebits > 16)
+ *val = sign_extend32(*(u32 *)(st->scan_data + 4 * scan_index),
+ scan_type->realbits - 1);
+ else
+ *val = sign_extend32(*(u16 *)(st->scan_data + 2 * scan_index),
+ scan_type->realbits - 1);
return IIO_VAL_INT;
}
@@ -369,11 +488,18 @@ static int ad7380_read_raw(struct iio_dev *indio_dev,
int *val, int *val2, long info)
{
struct ad7380_state *st = iio_priv(indio_dev);
+ const struct iio_scan_type *scan_type;
+
+ scan_type = iio_get_current_scan_type(indio_dev, chan);
+
+ if (IS_ERR(scan_type))
+ return PTR_ERR(scan_type);
switch (info) {
case IIO_CHAN_INFO_RAW:
iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
- return ad7380_read_direct(st, chan, val);
+ return ad7380_read_direct(st, chan->scan_index,
+ scan_type, val);
}
unreachable();
case IIO_CHAN_INFO_SCALE:
@@ -384,7 +510,7 @@ static int ad7380_read_raw(struct iio_dev *indio_dev,
* where N is the ADC resolution (i.e realbits)
*/
*val = st->vref_mv;
- *val2 = chan->scan_type.realbits - chan->differential;
+ *val2 = scan_type->realbits - chan->differential;
return IIO_VAL_FRACTIONAL_LOG2;
case IIO_CHAN_INFO_OFFSET:
@@ -392,17 +518,118 @@ static int ad7380_read_raw(struct iio_dev *indio_dev,
* According to IIO ABI, offset is applied before scale,
* so offset is: vcm_mv / scale
*/
- *val = st->vcm_mv[chan->channel] * (1 << chan->scan_type.realbits)
+ *val = st->vcm_mv[chan->channel] * (1 << scan_type->realbits)
/ st->vref_mv;
return IIO_VAL_INT;
+ case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+ *val = st->oversampling_ratio;
+
+ return IIO_VAL_INT;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int ad7380_read_avail(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ const int **vals, int *type, int *length,
+ long mask)
+{
+ switch (mask) {
+ case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+ *vals = ad7380_oversampling_ratios;
+ *length = ARRAY_SIZE(ad7380_oversampling_ratios);
+ *type = IIO_VAL_INT;
+
+ return IIO_AVAIL_LIST;
default:
return -EINVAL;
}
}
+/**
+ * ad7380_osr_to_regval - convert ratio to OSR register value
+ * @ratio: ratio to check
+ *
+ * Check if ratio is present in the list of available ratios and return the
+ * corresponding value that needs to be written to the register to select that
+ * ratio.
+ *
+ * Returns: register value (0 to 7) or -EINVAL if there is not an exact match
+ */
+static int ad7380_osr_to_regval(int ratio)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(ad7380_oversampling_ratios); i++) {
+ if (ratio == ad7380_oversampling_ratios[i])
+ return i;
+ }
+
+ return -EINVAL;
+}
+
+static int ad7380_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, int val,
+ int val2, long mask)
+{
+ struct ad7380_state *st = iio_priv(indio_dev);
+ int ret, osr, boost;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+ osr = ad7380_osr_to_regval(val);
+ if (osr < 0)
+ return osr;
+
+ /* always enable resolution boost when oversampling is enabled */
+ boost = osr > 0 ? 1 : 0;
+
+ iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
+ ret = regmap_update_bits(st->regmap,
+ AD7380_REG_ADDR_CONFIG1,
+ AD7380_CONFIG1_OSR | AD7380_CONFIG1_RES,
+ FIELD_PREP(AD7380_CONFIG1_OSR, osr) |
+ FIELD_PREP(AD7380_CONFIG1_RES, boost));
+
+ if (ret)
+ return ret;
+
+ st->oversampling_ratio = val;
+ st->resolution_boost_enabled = boost;
+
+ /*
+ * Perform a soft reset. This will flush the oversampling
+ * block and FIFO but will maintain the content of the
+ * configurable registers.
+ */
+ return regmap_update_bits(st->regmap,
+ AD7380_REG_ADDR_CONFIG2,
+ AD7380_CONFIG2_RESET,
+ FIELD_PREP(AD7380_CONFIG2_RESET,
+ AD7380_CONFIG2_RESET_SOFT));
+ }
+ unreachable();
+ default:
+ return -EINVAL;
+ }
+}
+
+static int ad7380_get_current_scan_type(const struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan)
+{
+ struct ad7380_state *st = iio_priv(indio_dev);
+
+ return st->resolution_boost_enabled ? AD7380_SCAN_TYPE_RESOLUTION_BOOST
+ : AD7380_SCAN_TYPE_NORMAL;
+}
+
static const struct iio_info ad7380_info = {
.read_raw = &ad7380_read_raw,
+ .read_avail = &ad7380_read_avail,
+ .write_raw = &ad7380_write_raw,
+ .get_current_scan_type = &ad7380_get_current_scan_type,
.debugfs_reg_access = &ad7380_debugfs_reg_access,
};
@@ -426,6 +653,9 @@ static int ad7380_init(struct ad7380_state *st, struct regulator *vref)
if (ret < 0)
return ret;
+ /* This is the default value after reset. */
+ st->oversampling_ratio = 1;
+
/* SPI 1-wire mode */
return regmap_update_bits(st->regmap, AD7380_REG_ADDR_CONFIG2,
AD7380_CONFIG2_SDO,
@@ -437,11 +667,6 @@ static void ad7380_regulator_disable(void *p)
regulator_disable(p);
}
-static void ad7380_unoptimize_msg(void *msg)
-{
- spi_unoptimize_message(msg);
-}
-
static int ad7380_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
@@ -532,32 +757,21 @@ static int ad7380_probe(struct spi_device *spi)
/*
* Setting up a low latency read for getting sample data. Used for both
- * direct read an triggered buffer.
+ * direct read an triggered buffer. Additional fields will be set up in
+ * ad7380_update_xfers() based on the current state of the driver at the
+ * time of the read.
*/
/* toggle CS (no data xfer) to trigger a conversion */
- st->xfer[0].delay.value = T_CONVERT_NS;
- st->xfer[0].delay.unit = SPI_DELAY_UNIT_NSECS;
st->xfer[0].cs_change = 1;
st->xfer[0].cs_change_delay.value = st->chip_info->timing_specs->t_csh_ns;
st->xfer[0].cs_change_delay.unit = SPI_DELAY_UNIT_NSECS;
/* then do a second xfer to read the data */
- st->xfer[1].bits_per_word = st->chip_info->channels[0].scan_type.realbits;
- st->xfer[1].rx_buf = st->scan_data.raw;
- st->xfer[1].len = BITS_TO_BYTES(st->chip_info->channels[0].scan_type.storagebits)
- * (st->chip_info->num_channels - 1);
+ st->xfer[1].rx_buf = st->scan_data;
spi_message_init_with_transfers(&st->msg, st->xfer, ARRAY_SIZE(st->xfer));
- ret = spi_optimize_message(st->spi, &st->msg);
- if (ret)
- return ret;
-
- ret = devm_add_action_or_reset(&spi->dev, ad7380_unoptimize_msg, &st->msg);
- if (ret)
- return ret;
-
indio_dev->channels = st->chip_info->channels;
indio_dev->num_channels = st->chip_info->num_channels;
indio_dev->name = st->chip_info->name;
@@ -567,7 +781,8 @@ static int ad7380_probe(struct spi_device *spi)
ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
iio_pollfunc_store_time,
- ad7380_trigger_handler, NULL);
+ ad7380_trigger_handler,
+ &ad7380_buffer_setup_ops);
if (ret)
return ret;
--
2.45.1
On Thu, 30 May 2024 10:14:07 -0500
David Lechner <[email protected]> wrote:
> Up to now, the IIO subsystem has only supported a single scan type per
> channel. This scan type determines the binary format of the data in the
> buffer when doing buffered reads.
>
> For simple devices, there is only one scan type and all is well. But
> for more complex devices, there may be multiple scan types. For example,
> ADCs with a resolution boost feature that adds more bits to the raw
> sample data. Traditionally, for slow devices, we've just always used the
> highest resolution mode, but for high performance ADCs, this may not be
> always practical. Manipulating data after every read can hurt performance
> and in the case of hardware buffers, it may not be possible to change the
> format of the data in the buffer at all. There are also ADCs where
> enabling the higher resolution can only be done if oversampling is also
> enabled which may not be desireable.
>
> To allow for more flexibility, we would like to add support for multiple
> scan types per channel.
>
> To avoid having to touch every driver, we implemented this in a way that
> preserves the existing scan_type field. See the "iio: add support for
> multiple scan types per channel" the details. The first couple of patches
> are just preparation for this.
>
> [1]: https://lore.kernel.org/linux-iio/CAMknhBHOXaff__QyU-wFSNNENvs23vDX5n_ddH-Dw3s6-sQ9sg@mail.gmail.com/
Nice series. Applied to the togreg branch of iio.git and pushed out as
testing for 0-day to poke at it.
Obviously this v3 hasn't been on list that long, but there is still time
as I doubt I'll push out a non rebasing tree for a week or so.
This week is looking too busy!
Thanks,
Jonathan
On Sun, 2 Jun 2024 10:25:17 +0100
Jonathan Cameron <[email protected]> wrote:
> On Thu, 30 May 2024 10:14:07 -0500
> David Lechner <[email protected]> wrote:
>
> > Up to now, the IIO subsystem has only supported a single scan type per
> > channel. This scan type determines the binary format of the data in the
> > buffer when doing buffered reads.
> >
> > For simple devices, there is only one scan type and all is well. But
> > for more complex devices, there may be multiple scan types. For example,
> > ADCs with a resolution boost feature that adds more bits to the raw
> > sample data. Traditionally, for slow devices, we've just always used the
> > highest resolution mode, but for high performance ADCs, this may not be
> > always practical. Manipulating data after every read can hurt performance
> > and in the case of hardware buffers, it may not be possible to change the
> > format of the data in the buffer at all. There are also ADCs where
> > enabling the higher resolution can only be done if oversampling is also
> > enabled which may not be desireable.
> >
> > To allow for more flexibility, we would like to add support for multiple
> > scan types per channel.
> >
> > To avoid having to touch every driver, we implemented this in a way that
> > preserves the existing scan_type field. See the "iio: add support for
> > multiple scan types per channel" the details. The first couple of patches
> > are just preparation for this.
> >
> > [1]: https://lore.kernel.org/linux-iio/CAMknhBHOXaff__QyU-wFSNNENvs23vDX5n_ddH-Dw3s6-sQ9sg@mail.gmail.com/
>
> Nice series. Applied to the togreg branch of iio.git and pushed out as
> testing for 0-day to poke at it.
>
> Obviously this v3 hasn't been on list that long, but there is still time
> as I doubt I'll push out a non rebasing tree for a week or so.
> This week is looking too busy!
oops. Goes to show I'm not keeping track of things very well today.
I haven't applied the driver this updates yet.
I'll look at that now and hopefully I can pick them both up.
Jonathan
>
> Thanks,
>
> Jonathan
>
>
>
On Sun, 2 Jun 2024 10:27:26 +0100
Jonathan Cameron <[email protected]> wrote:
> On Sun, 2 Jun 2024 10:25:17 +0100
> Jonathan Cameron <[email protected]> wrote:
>
> > On Thu, 30 May 2024 10:14:07 -0500
> > David Lechner <[email protected]> wrote:
> >
> > > Up to now, the IIO subsystem has only supported a single scan type per
> > > channel. This scan type determines the binary format of the data in the
> > > buffer when doing buffered reads.
> > >
> > > For simple devices, there is only one scan type and all is well. But
> > > for more complex devices, there may be multiple scan types. For example,
> > > ADCs with a resolution boost feature that adds more bits to the raw
> > > sample data. Traditionally, for slow devices, we've just always used the
> > > highest resolution mode, but for high performance ADCs, this may not be
> > > always practical. Manipulating data after every read can hurt performance
> > > and in the case of hardware buffers, it may not be possible to change the
> > > format of the data in the buffer at all. There are also ADCs where
> > > enabling the higher resolution can only be done if oversampling is also
> > > enabled which may not be desireable.
> > >
> > > To allow for more flexibility, we would like to add support for multiple
> > > scan types per channel.
> > >
> > > To avoid having to touch every driver, we implemented this in a way that
> > > preserves the existing scan_type field. See the "iio: add support for
> > > multiple scan types per channel" the details. The first couple of patches
> > > are just preparation for this.
> > >
> > > [1]: https://lore.kernel.org/linux-iio/CAMknhBHOXaff__QyU-wFSNNENvs23vDX5n_ddH-Dw3s6-sQ9sg@mail.gmail.com/
> >
> > Nice series. Applied to the togreg branch of iio.git and pushed out as
> > testing for 0-day to poke at it.
> >
> > Obviously this v3 hasn't been on list that long, but there is still time
> > as I doubt I'll push out a non rebasing tree for a week or so.
> > This week is looking too busy!
>
> oops. Goes to show I'm not keeping track of things very well today.
> I haven't applied the driver this updates yet.
>
> I'll look at that now and hopefully I can pick them both up.
>
That was fine, so both now applied.
> Jonathan
>
> >
> > Thanks,
> >
> > Jonathan
> >
> >
> >
>
>
On Sun, 2024-06-02 at 10:25 +0100, Jonathan Cameron wrote:
> On Thu, 30 May 2024 10:14:07 -0500
> David Lechner <[email protected]> wrote:
>
> > Up to now, the IIO subsystem has only supported a single scan type per
> > channel. This scan type determines the binary format of the data in the
> > buffer when doing buffered reads.
> >
> > For simple devices, there is only one scan type and all is well. But
> > for more complex devices, there may be multiple scan types. For example,
> > ADCs with a resolution boost feature that adds more bits to the raw
> > sample data. Traditionally, for slow devices, we've just always used the
> > highest resolution mode, but for high performance ADCs, this may not be
> > always practical. Manipulating data after every read can hurt performance
> > and in the case of hardware buffers, it may not be possible to change the
> > format of the data in the buffer at all. There are also ADCs where
> > enabling the higher resolution can only be done if oversampling is also
> > enabled which may not be desireable.
> >
> > To allow for more flexibility, we would like to add support for multiple
> > scan types per channel.
> >
> > To avoid having to touch every driver, we implemented this in a way that
> > preserves the existing scan_type field. See the "iio: add support for
> > multiple scan types per channel" the details. The first couple of patches
> > are just preparation for this.
> >
> > [1]:
> > https://lore.kernel.org/linux-iio/CAMknhBHOXaff__QyU-wFSNNENvs23vDX5n_ddH-Dw3s6-sQ9sg@mail.gmail.com/
>
> Nice series. Applied to the togreg branch of iio.git and pushed out as
> testing for 0-day to poke at it.
>
> Obviously this v3 hasn't been on list that long, but there is still time
> as I doubt I'll push out a non rebasing tree for a week or so.
> This week is looking too busy!
If there's still time, feel free to add my tag:
Reviewed-by: Nuno Sa <[email protected]>
On Mon, 03 Jun 2024 12:25:55 +0200
Nuno Sá <[email protected]> wrote:
> On Sun, 2024-06-02 at 10:25 +0100, Jonathan Cameron wrote:
> > On Thu, 30 May 2024 10:14:07 -0500
> > David Lechner <[email protected]> wrote:
> >
> > > Up to now, the IIO subsystem has only supported a single scan type per
> > > channel. This scan type determines the binary format of the data in the
> > > buffer when doing buffered reads.
> > >
> > > For simple devices, there is only one scan type and all is well. But
> > > for more complex devices, there may be multiple scan types. For example,
> > > ADCs with a resolution boost feature that adds more bits to the raw
> > > sample data. Traditionally, for slow devices, we've just always used the
> > > highest resolution mode, but for high performance ADCs, this may not be
> > > always practical. Manipulating data after every read can hurt performance
> > > and in the case of hardware buffers, it may not be possible to change the
> > > format of the data in the buffer at all. There are also ADCs where
> > > enabling the higher resolution can only be done if oversampling is also
> > > enabled which may not be desireable.
> > >
> > > To allow for more flexibility, we would like to add support for multiple
> > > scan types per channel.
> > >
> > > To avoid having to touch every driver, we implemented this in a way that
> > > preserves the existing scan_type field. See the "iio: add support for
> > > multiple scan types per channel" the details. The first couple of patches
> > > are just preparation for this.
> > >
> > > [1]:
> > > https://lore.kernel.org/linux-iio/CAMknhBHOXaff__QyU-wFSNNENvs23vDX5n_ddH-Dw3s6-sQ9sg@mail.gmail.com/
> >
> > Nice series. Applied to the togreg branch of iio.git and pushed out as
> > testing for 0-day to poke at it.
> >
> > Obviously this v3 hasn't been on list that long, but there is still time
> > as I doubt I'll push out a non rebasing tree for a week or so.
> > This week is looking too busy!
>
> If there's still time, feel free to add my tag:
>
> Reviewed-by: Nuno Sa <[email protected]>
>
Done