@@ -10320,6 +10320,14 @@ L: linux-media@vger.kernel.org
S: Maintained
F: drivers/media/rc/iguanair.c
+IIO BACKEND FRAMEWORK
+M: Nuno Sa <nuno.sa@analog.com>
+R: Olivier Moysan <olivier.moysan@foss.st.com>
+L: linux-iio@vger.kernel.org
+S: Maintained
+F: drivers/iio/industrialio-backend.c
+F: include/linux/iio/backend.h
+
IIO DIGITAL POTENTIOMETER DAC
M: Peter Rosin <peda@axentia.se>
L: linux-iio@vger.kernel.org
@@ -71,6 +71,11 @@ config IIO_TRIGGERED_EVENT
help
Provides helper functions for setting up triggered events.
+config IIO_BACKEND
+ tristate
+ help
+ Framework to handle complex IIO aggregate devices.
+
source "drivers/iio/accel/Kconfig"
source "drivers/iio/adc/Kconfig"
source "drivers/iio/addac/Kconfig"
@@ -13,6 +13,7 @@ obj-$(CONFIG_IIO_GTS_HELPER) += industrialio-gts-helper.o
obj-$(CONFIG_IIO_SW_DEVICE) += industrialio-sw-device.o
obj-$(CONFIG_IIO_SW_TRIGGER) += industrialio-sw-trigger.o
obj-$(CONFIG_IIO_TRIGGERED_EVENT) += industrialio-triggered-event.o
+obj-$(CONFIG_IIO_BACKEND) += industrialio-backend.o
obj-y += accel/
obj-y += adc/
new file mode 100644
@@ -0,0 +1,386 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Framework to handle complex IIO aggregate devices.
+ *
+ * The typical architecture is to have one device as the frontend device which
+ * can be "linked" against one or multiple backend devices. All the IIO and
+ * userspace interface is expected to be registers/managed by the frontend
+ * device which will callback into the backends when needed (to get/set some
+ * configuration that it does not directly control).
+ *
+ * The framework interface is pretty simple:
+ * - Backends should register themselves with @devm_iio_backend_register()
+ * - Frontend devices should get backends with @devm_iio_backend_get()
+ *
+ * Also to note that the primary target for this framework are converters like
+ * ADC/DACs so @iio_backend_ops will have some operations typical of converter
+ * devices. On top of that, this is "generic" for all IIO which means any kind
+ * of device can make use of the framework. That said, If the @iio_backend_ops
+ * struct begins to grow out of control, we can always refactor things so that
+ * the industrialio-backend.c is only left with the really generic stuff. Then,
+ * we can build on top of it depending on the needs.
+ *
+ * Copyright (C) 2023 Analog Devices Inc.
+ */
+#define pr_fmt(fmt) "iio-backend: " fmt
+
+#include <linux/cleanup.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/list.h>
+#include <linux/lockdep.h>
+#include <linux/kref.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+
+#include <linux/iio/backend.h>
+
+struct iio_backend {
+ struct list_head entry;
+ const struct iio_backend_ops *ops;
+ struct device *dev;
+ struct module *owner;
+ void *priv;
+ /*
+ * mutex used to synchronize backend callback access with concurrent
+ * calls to @iio_backend_unregister. The lock makes sure a device is
+ * not unregistered while a callback is being run.
+ */
+ struct mutex lock;
+ struct kref ref;
+};
+
+/*
+ * Helper struct for requesting buffers. Allows for multiple buffers per
+ * backend.
+ */
+struct iio_backend_buffer_pair {
+ struct iio_backend *back;
+ struct iio_buffer *buffer;
+};
+
+static LIST_HEAD(iio_back_list);
+static DEFINE_MUTEX(iio_back_lock);
+
+/*
+ * Helper macros to properly call backend ops. The main point for these macros
+ * is to properly lock the backend mutex on every call plus checking if the
+ * backend device is still around (by looking at the *ops pointer).
+ */
+
+#define iio_backend_check_op(back, op) ({ \
+ struct iio_backend *____back = back; \
+ int ____ret = 0; \
+ \
+ lockdep_assert_held(&____back->lock); \
+ if (!____back->ops) { \
+ pr_warn_once("Backend is no longer available\n"); \
+ ____ret = -ENODEV; \
+ } else if (!____back->ops->op) { \
+ ____ret = -EOPNOTSUPP; \
+ } \
+ \
+ ____ret; \
+})
+
+#define iio_backend_op_call(back, op, args...) ({ \
+ struct iio_backend *__back = back; \
+ int __ret; \
+ \
+ guard(mutex)(&__back->lock); \
+ __ret = iio_backend_check_op(__back, op); \
+ if (!__ret) \
+ __ret = __back->ops->op(__back, ##args); \
+ \
+ __ret; \
+})
+
+#define iio_backend_ptr_op_call(back, op, args...) ({ \
+ struct iio_backend *__back = back; \
+ void *ptr_err; \
+ int __ret; \
+ \
+ guard(mutex)(&__back->lock); \
+ __ret = iio_backend_check_op(__back, op); \
+ if (__ret) \
+ ptr_err = ERR_PTR(__ret); \
+ else \
+ ptr_err = __back->ops->op(__back, ##args); \
+ \
+ ptr_err; \
+})
+
+#define iio_backend_void_op_call(back, op, args...) { \
+ struct iio_backend *__back = back; \
+ int __ret; \
+ \
+ guard(mutex)(&__back->lock); \
+ __ret = iio_backend_check_op(__back, op); \
+ if (!__ret) \
+ __back->ops->op(__back, ##args); \
+}
+
+/**
+ * iio_backend_chan_enable - Enable a backend channel.
+ * @back: Backend device.
+ * @chan: Channel number.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_chan_enable(struct iio_backend *back, unsigned int chan)
+{
+ return iio_backend_op_call(back, chan_enable, chan);
+}
+EXPORT_SYMBOL_GPL(iio_backend_chan_enable);
+
+/**
+ * iio_backend_chan_disable - Disable a backend channel.
+ * @back: Backend device.
+ * @chan: Channel number.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_chan_disable(struct iio_backend *back, unsigned int chan)
+{
+ return iio_backend_op_call(back, chan_disable, chan);
+}
+EXPORT_SYMBOL_GPL(iio_backend_chan_disable);
+
+/**
+ * iio_backend_chan_enable - Enable the backend.
+ * @back: Backend device
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_enable(struct iio_backend *back)
+{
+ return iio_backend_op_call(back, enable);
+}
+EXPORT_SYMBOL_GPL(iio_backend_enable);
+
+/**
+ * iio_backend_disable - Disable the backend.
+ * @back: Backend device
+ */
+void iio_backend_disable(struct iio_backend *back)
+{
+ iio_backend_void_op_call(back, disable);
+}
+EXPORT_SYMBOL_GPL(iio_backend_disable);
+
+/**
+ * iio_backend_data_format_set - Configure the channel data format
+ * @back: Backend device
+ * @chan: Channel number.
+ * @data: Data format.
+ *
+ * Properly configure a channel with respect to the expected data format. A
+ * @struct iio_backend_data_fmt must be passed with the settings.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure
+ */
+int iio_backend_data_format_set(struct iio_backend *back, unsigned int chan,
+ const struct iio_backend_data_fmt *data)
+{
+ if (!data || data->type >= IIO_BACKEND_DATA_TYPE_MAX)
+ return -EINVAL;
+
+ return iio_backend_op_call(back, data_format_set, chan, data);
+}
+EXPORT_SYMBOL_GPL(iio_backend_data_format_set);
+
+static void iio_backend_free_buffer(void *arg)
+{
+ struct iio_backend_buffer_pair *pair = arg;
+
+ iio_backend_void_op_call(pair->back, free_buffer, pair->buffer);
+}
+
+/**
+ * devm_iio_backend_request_buffer - Request an IIO buffer from the backend.
+ * @dev: Device to bind the buffer lifetime.
+ * @back: Backend device.
+ * @indio_dev: IIO device.
+ *
+ * Request an IIO buffer from the backend. The type of the buffer (typically
+ * INDIO_BUFFER_HARDWARE) is up to the backend to decide. This is because,
+ * normally, the backend dictates what kind of buffering we can get.
+ *
+ * The backend .free_buffer() hooks is automatically called on @dev detach.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure
+ */
+int devm_iio_backend_request_buffer(struct device *dev,
+ struct iio_backend *back,
+ struct iio_dev *indio_dev)
+{
+ struct iio_backend_buffer_pair *pair;
+ struct iio_buffer *buffer;
+
+ buffer = iio_backend_ptr_op_call(back, request_buffer, indio_dev);
+ if (IS_ERR(buffer))
+ return PTR_ERR(buffer);
+
+ /* backend lock should not be need after getting the buffer */
+ pair = devm_kzalloc(dev, sizeof(*pair), GFP_KERNEL);
+ if (!pair)
+ return -ENOMEM;
+
+ /* weak reference should be all what we need */
+ pair->back = back;
+ pair->buffer = buffer;
+
+ return devm_add_action_or_reset(dev, iio_backend_free_buffer, pair);
+}
+EXPORT_SYMBOL_GPL(devm_iio_backend_request_buffer);
+
+static void iio_backend_free(struct kref *ref)
+{
+ struct iio_backend *back = container_of(ref, struct iio_backend, ref);
+
+ kfree(back);
+}
+
+static void iio_backend_release(void *arg)
+{
+ struct iio_backend *back = arg;
+
+ module_put(back->owner);
+ kref_put(&back->ref, iio_backend_free);
+}
+
+/**
+ * devm_iio_backend_get - Get a backend device
+ * @dev: Device where to look for the backend.
+ * @name: Backend name.
+ *
+ * Get's the backend associated with @dev.
+ *
+ * RETURNS:
+ * A backend pointer, negative error pointer otherwise.
+ */
+struct iio_backend *devm_iio_backend_get(struct device *dev, const char *name)
+{
+ struct fwnode_handle *fwnode;
+ struct iio_backend *back;
+ int index = 0, ret;
+
+ if (name) {
+ index = device_property_match_string(dev, "io-backends-names",
+ name);
+ if (index < 0)
+ return ERR_PTR(index);
+ }
+
+ fwnode = fwnode_find_reference(dev_fwnode(dev), "io-backends", index);
+ if (IS_ERR(fwnode)) {
+ dev_err(dev, "Cannot get Firmware reference\n");
+ return ERR_CAST(fwnode);
+ }
+
+ guard(mutex)(&iio_back_lock);
+ list_for_each_entry(back, &iio_back_list, entry) {
+ struct device_link *link;
+
+ if (!device_match_fwnode(back->dev, fwnode))
+ continue;
+
+ fwnode_handle_put(fwnode);
+ kref_get(&back->ref);
+ if (!try_module_get(back->owner)) {
+ dev_err(dev, "Cannot get module reference\n");
+ return ERR_PTR(-ENODEV);
+ }
+
+ ret = devm_add_action_or_reset(dev, iio_backend_release, back);
+ if (ret)
+ return ERR_PTR(ret);
+
+ link = device_link_add(dev, back->dev,
+ DL_FLAG_AUTOREMOVE_CONSUMER);
+ if (!link)
+ dev_warn(dev, "Could not link to supplier(%s)\n",
+ dev_name(back->dev));
+
+ dev_dbg(dev, "Found backend(%s) device\n", dev_name(back->dev));
+ return back;
+ }
+
+ fwnode_handle_put(fwnode);
+ return ERR_PTR(-EPROBE_DEFER);
+}
+EXPORT_SYMBOL_GPL(devm_iio_backend_get);
+
+/**
+ * iio_backend_get_priv - Get driver private data
+ * @back: Backend device
+ */
+void *iio_backend_get_priv(const struct iio_backend *back)
+{
+ return back->priv;
+}
+EXPORT_SYMBOL_GPL(iio_backend_get_priv);
+
+static void iio_backend_unregister(void *arg)
+{
+ struct iio_backend *back = arg;
+
+ mutex_lock(&iio_back_lock);
+ list_del(&back->entry);
+ mutex_unlock(&iio_back_lock);
+
+ mutex_lock(&back->lock);
+ back->ops = NULL;
+ mutex_unlock(&back->lock);
+ kref_put(&back->ref, iio_backend_free);
+}
+
+/**
+ * devm_iio_backend_register - Register a new backend device
+ * @dev: Backend device being registered.
+ * @ops: Backend ops
+ * @priv: Device private data.
+ *
+ * @ops and @priv are both mandatory. Not providing them results in -EINVAL.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int devm_iio_backend_register(struct device *dev,
+ const struct iio_backend_ops *ops, void *priv)
+{
+ struct iio_backend *back;
+
+ if (!ops || !priv) {
+ dev_err(dev, "No backend ops or private data given\n");
+ return -EINVAL;
+ }
+
+ back = kzalloc(sizeof(*back), GFP_KERNEL);
+ if (!back)
+ return -ENOMEM;
+
+ kref_init(&back->ref);
+ mutex_init(&back->lock);
+ back->ops = ops;
+ back->owner = dev->driver->owner;
+ back->dev = dev;
+ back->priv = priv;
+ mutex_lock(&iio_back_lock);
+ list_add(&back->entry, &iio_back_list);
+ mutex_unlock(&iio_back_lock);
+
+ return devm_add_action_or_reset(dev, iio_backend_unregister, back);
+}
+EXPORT_SYMBOL_GPL(devm_iio_backend_register);
+
+MODULE_AUTHOR("Nuno Sa <nuno.sa@analog.com>");
+MODULE_DESCRIPTION("Framework to handle complex IIO aggregate devices");
+MODULE_LICENSE("GPL");
new file mode 100644
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _IIO_BACKEND_H_
+#define _IIO_BACKEND_H_
+
+#include <linux/types.h>
+
+struct iio_backend;
+struct device;
+struct iio_dev;
+
+enum iio_backend_data_type {
+ IIO_BACKEND_TWOS_COMPLEMENT,
+ IIO_BACKEND_OFFSET_BINARY,
+ IIO_BACKEND_DATA_TYPE_MAX
+};
+
+/**
+ * struct iio_backend_data_fmt - Backend data format
+ * @type: Data type.
+ * @sign_extend: Bool to tell if the data is sign extended.
+ * @enable: Enable/Disable the data format module. If disabled,
+ * not formatting will happen.
+ */
+struct iio_backend_data_fmt {
+ enum iio_backend_data_type type;
+ bool sign_extend;
+ bool enable;
+};
+
+/**
+ * struct iio_backend_ops - operations structure for an iio_backend
+ * @enable: Enable backend.
+ * @disable: Disable backend.
+ * @chan_enable: Enable one channel.
+ * @chan_disable: Disable one channel.
+ * @data_format_set: Configure the data format for a specific channel.
+ * @request_buffer: Request an IIO buffer.
+ * @free_buffer: Free an IIO buffer.
+ **/
+struct iio_backend_ops {
+ int (*enable)(struct iio_backend *back);
+ void (*disable)(struct iio_backend *back);
+ int (*chan_enable)(struct iio_backend *back, unsigned int chan);
+ int (*chan_disable)(struct iio_backend *back, unsigned int chan);
+ int (*data_format_set)(struct iio_backend *back, unsigned int chan,
+ const struct iio_backend_data_fmt *data);
+ struct iio_buffer *(*request_buffer)(struct iio_backend *back,
+ struct iio_dev *indio_dev);
+ void (*free_buffer)(struct iio_backend *back,
+ struct iio_buffer *buffer);
+};
+
+int iio_backend_chan_enable(struct iio_backend *back, unsigned int chan);
+int iio_backend_chan_disable(struct iio_backend *back, unsigned int chan);
+int iio_backend_enable(struct iio_backend *back);
+void iio_backend_disable(struct iio_backend *back);
+int iio_backend_data_format_set(struct iio_backend *back, unsigned int chan,
+ const struct iio_backend_data_fmt *data);
+int devm_iio_backend_request_buffer(struct device *dev,
+ struct iio_backend *back,
+ struct iio_dev *indio_dev);
+
+void *iio_backend_get_priv(const struct iio_backend *conv);
+struct iio_backend *devm_iio_backend_get(struct device *dev, const char *name);
+int devm_iio_backend_register(struct device *dev,
+ const struct iio_backend_ops *ops, void *priv);
+
+#endif