Merge tag 'iio-for-6.10a' of https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into char-misc-next

Jonathan writes:

IIO: 1st set of new device support, features and cleanup for 6.10

The Analog Device team (Paul Cercueil and Nuno Sa) have been working on
improving high speed device handling. They have had some support in their
own tree for many years, so it is great to see them bring it to upstream.
Some of that is seen here, with the first output device using the
IIO dmaengine infrastructure and a new DAC backend FPGA IP driver.
This makes use of a new set of interfaces to allow backend and
front end driver communication in a fashion that in theory at least
allows for a single driver for a given ADC / DAC independent of
the IP to which is being used to deal with the data bus and DMA aspects
of working with these devices. It is early days for this new
generic way of handling split devices, but as it's kernel internals only
we can merrily change anything about it as a wider diversity of devices
show up and we get a better feel for what works.

Alongside the usual set of new drivers and features we have
the automatic cleanup of fwnode_handle_put() which didn't quite make
it in last cycle. The equivalent DT version was merged by Rob Herring
via the DT binding tree and one patch using that in IIO can also be
found in this pull request. Rob has been making extensive use of that
infrastructure in the DT core which is good to see and provides more
evidence this basic approach is useful.

In some cases, the IIO driver was converted over from DT only to
using the generic firmware description handling of property.h
including using the new macros. The general preference for IIO
is to use this more generic handling where possible - a bunch of other
drivers have been converted this cycle as well.

New device support
==================

adi,ad7173
- New driver supporting AD7172-2, AD7172-4 AD7173-9, AD7175-2, AD7175-8,
  AD7176-2 and AD7177-2 ADCs.
- Follow up fix for an accidental use of logic not instead of bitwise.

adi,ad7944
- New driver supporting AD7944, AD7985 and AD7986 pin compatible ADCs.
- Later patch added use of new spi_optimize_message() to reduce overheads
  of setting up a reused message.
- Additional changes later in series reduced code duplication.

adi,ad9739a RF DAC
- New driver for this 14-bit 2.5 GSPS DAC via an LVDS interface.

adi,axi-dac
- Support for this FPGA IP used to send data to high performance DACs over
  an interface such as JESD204B/C or parallel interfaces.  Used in
  conjunction with a DAC driver. The initial user is the ad9739a.
  The dmaengine-buffer needed various changes to make it bidirectional.

avago,apds9306
- New driver for this ambient light sensor.
- Fix much later in this pull for an off by 1 error.

New device IDs
==============

For these at most an ID and a instance of chip specific data was needed.
Always nice to see manufacturers sticking to an existing software interface
for new parts.

allwinner,sun20i
- Add support for h616.
invensense,mpu6050
- Add support for ICM42688
maxim,max30102
- Add compatible for MAX30101
ti,dac5571
- Add compatible for DAC081C081

General
=======

fwnode_handle
- Support for cleanup.h based __free(fwnode_handle)
- Loop macro using this for looping over child nodes without needing to
  call fwnode_handle_put() in ever early exit from the loop.
- Used in:
  * adi,ad3552r
  * adi,ad4130
  * adi,ad5770r
  * adi,ad74413r
  * adi,ad7173
  * adi,adfm2000
  * linear,ltc2688
  * linear,ltc2983
  * maxim,max11410
  * microchip,pac1934
  * qcom,spmi-adc
  * renesas,rz2gl
  * st,ab8500
  * st,stm32 (Fix for failure to set return value precedes this patch,
    providing an example of why enabling direct returns makes bugs
    less likely)
- Conversions to fwnode also using the cleanup logic
  * adi,ad7124
  * adi,ad7292
  * freescale,fsl-imx25-gcq

- Other conversions to fwnode where the new cleanup handling isn't useful
  * adi,ad7192
  * avia,hx711
  * freescale,mma8452
  * nxp,fxls8962af
  * st,spear
  * ti,twl4030

Features
========

adi,adxl345
- Support SPI_3WIRE mode.

adi,ad9944
- Support 3-wire mode, note this isn't normal 3-wire SPI (unlike the
  adxl345 change above), but rather   a wiring scheme where the SPI
  chip select is used to trigger conversions rather than using a
  separate pin.
- Add some device specific documentation, mostly around the various wiring
  schemes.

invensense,mpu6050
- Add Wake on Motion support as an IIO event and as a wake-up source.

linear,ltc2983
- Add vdd-supply.

ti,hdc3020
- Add power management using trigger on demand mode and adding suspend and
  resume handling.
- Use reset GPIO if available.

Cleanup and fixes
================

iio core
- Use the various autocleanup and lock guards from cleanup.h to simplify
  the IIO core.
- Don't set the pointer used for iio_priv() if it is zero sized as that
  points beyond the end of the allocation. No driver actually uses it
  in that case but good to clean this up.

various drivers
- Drop unnecessary casts of other pointer types to void *

docs
- Add missing ABI entry for in_temp_input.

adi,adx345
- General cleanup prior to adding spi-3wire mode.

adi,axi-adc
- Be more flexible and allow minor version changes as these are expected
  to be backwards compatible.

avago,apds9300/9600
- Merge near identical bindings. The drivers are quite different, but
  the bindings can be shared. The apds9306 binding introduced in this
  series uses this shared binding doc as well.
- Add missing vdd-supply
- Update binding to use IRQ_TYPE_LEVEL_LOW instead of 8.

bosch,bmp280
- Organize headers

freescale,fxl-imx25-gcq
- Use devm_ for remaining probe() time setup allowing dropping
  of specific error handling and remove() functions.

infineon,dps310
- Fix handling of negative temperatures
- Bring style of other similar calls inline with the form needed
  for temperatures
- Ensure error handling of regmap calls is consistent within the driver.
- Simplify scale reading logic.

invensense,mpu6050
- Flip logic in binding to exclude devices without i2c-gate instead
  of opting in.  The list is expected to be much shorter as all recent
  devices support this feature.

honeywell,hsc030pa
- Use spi_read() instead of opening coding.

renesas,rcar
- Use device_for_each_child_of_node_scoped() to remove need to manually
  release. Left over from series the rest of which went in during 6.9.

st,ab8500
- Fix naming of function parameters in kernel-doc

* tag 'iio-for-6.10a' of https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio: (108 commits)
  iio: adc: ti-ads131e08: Use device_for_each_child_node_scoped() to simplify error paths.
  iio: adc: adi-axi-adc: only error out in major version mismatch
  iio: dac: support the ad9739a RF DAC
  iio: dac: add support for AXI DAC IP core
  iio: backend: add new functionality
  dt-bindings: iio: dac: add docs for AD9739A
  dt-bindings: iio: dac: add docs for AXI DAC IP
  iio: buffer-dmaengine: Enable write support
  iio: buffer-dmaengine: Support specifying buffer direction
  iio: buffer-dma: Enable buffer write support
  iio: buffer-dma: Rename iio_dma_buffer_data_available()
  iio: buffer-dma: add iio_dmaengine_buffer_setup()
  iio: pressure: dps310: simplify scale factor reading
  iio: pressure: dps310: consistently check return value of `regmap_read`
  iio: pressure: dps310: introduce consistent error handling
  iio: pressure: dps310: support negative temperature values
  dt-bindings: iio: adc: Add GPADC for Allwinner H616
  iio: dac: ad5755: make use of of_device_id table
  iio: imu: inv_icm42600: add support of ICM-42688-P
  dt-bindings: iio: imu: add icm42688 inside inv_icm42600
  ...

1 files changed, 179 insertions, 0 deletions

diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
index 2fea2bbbe47f..f08ed6d70ae5 100644
--- a/drivers/iio/industrialio-backend.c
+++ b/drivers/iio/industrialio-backend.c
@@ -43,10 +43,12 @@
 #include <linux/types.h>
 
 #include <linux/iio/backend.h>
+#include <linux/iio/iio.h>
 
 struct iio_backend {
 	struct list_head entry;
 	const struct iio_backend_ops *ops;
+	struct device *frontend_dev;
 	struct device *dev;
 	struct module *owner;
 	void *priv;
@@ -186,6 +188,44 @@ int iio_backend_data_format_set(struct iio_backend *back, unsigned int chan,
 }
 EXPORT_SYMBOL_NS_GPL(iio_backend_data_format_set, IIO_BACKEND);
 
+/**
+ * iio_backend_data_source_set - Select data source
+ * @back:	Backend device
+ * @chan:	Channel number
+ * @data:	Data source
+ *
+ * A given backend may have different sources to stream/sync data. This allows
+ * to choose that source.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_data_source_set(struct iio_backend *back, unsigned int chan,
+				enum iio_backend_data_source data)
+{
+	if (data >= IIO_BACKEND_DATA_SOURCE_MAX)
+		return -EINVAL;
+
+	return iio_backend_op_call(back, data_source_set, chan, data);
+}
+EXPORT_SYMBOL_NS_GPL(iio_backend_data_source_set, IIO_BACKEND);
+
+/**
+ * iio_backend_set_sampling_freq - Set channel sampling rate
+ * @back:		Backend device
+ * @chan:		Channel number
+ * @sample_rate_hz:	Sample rate
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_set_sampling_freq(struct iio_backend *back, unsigned int chan,
+				  u64 sample_rate_hz)
+{
+	return iio_backend_op_call(back, set_sample_rate, chan, sample_rate_hz);
+}
+EXPORT_SYMBOL_NS_GPL(iio_backend_set_sampling_freq, IIO_BACKEND);
+
 static void iio_backend_free_buffer(void *arg)
 {
 	struct iio_backend_buffer_pair *pair = arg;
@@ -231,6 +271,143 @@ int devm_iio_backend_request_buffer(struct device *dev,
 }
 EXPORT_SYMBOL_NS_GPL(devm_iio_backend_request_buffer, IIO_BACKEND);
 
+static struct iio_backend *iio_backend_from_indio_dev_parent(const struct device *dev)
+{
+	struct iio_backend *back = ERR_PTR(-ENODEV), *iter;
+
+	/*
+	 * We deliberately go through all backends even after finding a match.
+	 * The reason is that we want to catch frontend devices which have more
+	 * than one backend in which case returning the first we find is bogus.
+	 * For those cases, frontends need to explicitly define
+	 * get_iio_backend() in struct iio_info.
+	 */
+	guard(mutex)(&iio_back_lock);
+	list_for_each_entry(iter, &iio_back_list, entry) {
+		if (dev == iter->frontend_dev) {
+			if (!IS_ERR(back)) {
+				dev_warn(dev,
+					 "Multiple backends! get_iio_backend() needs to be implemented");
+				return ERR_PTR(-ENODEV);
+			}
+
+			back = iter;
+		}
+	}
+
+	return back;
+}
+
+/**
+ * iio_backend_ext_info_get - IIO ext_info read callback
+ * @indio_dev:	IIO device
+ * @private:	Data private to the driver
+ * @chan:	IIO channel
+ * @buf:	Buffer where to place the attribute data
+ *
+ * This helper is intended to be used by backends that extend an IIO channel
+ * (through iio_backend_extend_chan_spec()) with extended info. In that case,
+ * backends are not supposed to give their own callbacks (as they would not have
+ * a way to get the backend from indio_dev). This is the getter.
+ *
+ * RETURNS:
+ * Number of bytes written to buf, negative error number on failure.
+ */
+ssize_t iio_backend_ext_info_get(struct iio_dev *indio_dev, uintptr_t private,
+				 const struct iio_chan_spec *chan, char *buf)
+{
+	struct iio_backend *back;
+
+	/*
+	 * The below should work for the majority of the cases. It will not work
+	 * when one frontend has multiple backends in which case we'll need a
+	 * new callback in struct iio_info so we can directly request the proper
+	 * backend from the frontend. Anyways, let's only introduce new options
+	 * when really needed...
+	 */
+	back = iio_backend_from_indio_dev_parent(indio_dev->dev.parent);
+	if (IS_ERR(back))
+		return PTR_ERR(back);
+
+	return iio_backend_op_call(back, ext_info_get, private, chan, buf);
+}
+EXPORT_SYMBOL_NS_GPL(iio_backend_ext_info_get, IIO_BACKEND);
+
+/**
+ * iio_backend_ext_info_set - IIO ext_info write callback
+ * @indio_dev:	IIO device
+ * @private:	Data private to the driver
+ * @chan:	IIO channel
+ * @buf:	Buffer holding the sysfs attribute
+ * @len:	Buffer length
+ *
+ * This helper is intended to be used by backends that extend an IIO channel
+ * (trough iio_backend_extend_chan_spec()) with extended info. In that case,
+ * backends are not supposed to give their own callbacks (as they would not have
+ * a way to get the backend from indio_dev). This is the setter.
+ *
+ * RETURNS:
+ * Buffer length on success, negative error number on failure.
+ */
+ssize_t iio_backend_ext_info_set(struct iio_dev *indio_dev, uintptr_t private,
+				 const struct iio_chan_spec *chan,
+				 const char *buf, size_t len)
+{
+	struct iio_backend *back;
+
+	back = iio_backend_from_indio_dev_parent(indio_dev->dev.parent);
+	if (IS_ERR(back))
+		return PTR_ERR(back);
+
+	return iio_backend_op_call(back, ext_info_set, private, chan, buf, len);
+}
+EXPORT_SYMBOL_NS_GPL(iio_backend_ext_info_set, IIO_BACKEND);
+
+/**
+ * iio_backend_extend_chan_spec - Extend an IIO channel
+ * @indio_dev:	IIO device
+ * @back:	Backend device
+ * @chan:	IIO channel
+ *
+ * Some backends may have their own functionalities and hence capable of
+ * extending a frontend's channel.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_extend_chan_spec(struct iio_dev *indio_dev,
+				 struct iio_backend *back,
+				 struct iio_chan_spec *chan)
+{
+	const struct iio_chan_spec_ext_info *frontend_ext_info = chan->ext_info;
+	const struct iio_chan_spec_ext_info *back_ext_info;
+	int ret;
+
+	ret = iio_backend_op_call(back, extend_chan_spec, chan);
+	if (ret)
+		return ret;
+	/*
+	 * Let's keep things simple for now. Don't allow to overwrite the
+	 * frontend's extended info. If ever needed, we can support appending
+	 * it.
+	 */
+	if (frontend_ext_info && chan->ext_info != frontend_ext_info)
+		return -EOPNOTSUPP;
+	if (!chan->ext_info)
+		return 0;
+
+	/* Don't allow backends to get creative and force their own handlers */
+	for (back_ext_info = chan->ext_info; back_ext_info->name; back_ext_info++) {
+		if (back_ext_info->read != iio_backend_ext_info_get)
+			return -EINVAL;
+		if (back_ext_info->write != iio_backend_ext_info_set)
+			return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(iio_backend_extend_chan_spec, IIO_BACKEND);
+
 static void iio_backend_release(void *arg)
 {
 	struct iio_backend *back = arg;
@@ -263,6 +440,8 @@ static int __devm_iio_backend_get(struct device *dev, struct iio_backend *back)
 				     "Could not link to supplier(%s)\n",
 				     dev_name(back->dev));
 
+	back->frontend_dev = dev;
+
 	dev_dbg(dev, "Found backend(%s) device\n", dev_name(back->dev));
 
 	return 0;