[PATCH 08/13] iio: buffer: add new hardware triggered buffer driver

[David Lechner <dlechner@xxxxxxxxxxxx>]

This adds a new hardware triggered buffer driver for the IIO subsystem.
This driver is intended to be used by IIO device drivers that have
a hardware buffer that is triggered by a hardware signal.

It is expected that components such as those providing a backend via the
IIO backend framework will provide the actual implementation of this
functionality by registering a matching device on the auxiliary bus.
The auxiliary bus was chosen since it allows us to make use of existing
kernel infrastructure instead of implementing our own registration and
lookup system.

Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx>
---
 Documentation/driver-api/driver-model/devres.rst   |   1 +
 drivers/iio/buffer/Kconfig                         |   7 ++
 drivers/iio/buffer/Makefile                        |   1 +
 .../iio/buffer/industrialio-hw-triggered-buffer.c  | 104 +++++++++++++++++++++
 include/linux/iio/hw_triggered_buffer.h            |  14 +++
 include/linux/iio/hw_triggered_buffer_impl.h       |  16 ++++
 6 files changed, 143 insertions(+)

diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst
index c5f99d834ec5..b23d4a2b68a6 100644
--- a/Documentation/driver-api/driver-model/devres.rst
+++ b/Documentation/driver-api/driver-model/devres.rst
@@ -296,6 +296,7 @@ IIO
   devm_iio_channel_get()
   devm_iio_channel_get_all()
   devm_iio_hw_consumer_alloc()
+  devm_iio_hw_triggered_buffer_setup()
   devm_fwnode_iio_channel_get_by_name()
 
 INPUT
diff --git a/drivers/iio/buffer/Kconfig b/drivers/iio/buffer/Kconfig
index 047b931591a9..925c5bf074bc 100644
--- a/drivers/iio/buffer/Kconfig
+++ b/drivers/iio/buffer/Kconfig
@@ -53,3 +53,10 @@ config IIO_TRIGGERED_BUFFER
 	select IIO_KFIFO_BUF
 	help
 	  Provides helper functions for setting up triggered buffers.
+
+config IIO_HW_TRIGGERED_BUFFER
+	tristate "Industrial I/O hardware triggered buffer support"
+	select AUXILIARY_BUS
+	select IIO_TRIGGER
+	help
+	  Provides helper functions for setting up hardware triggered buffers.
diff --git a/drivers/iio/buffer/Makefile b/drivers/iio/buffer/Makefile
index 1403eb2f9409..d1142bb20f61 100644
--- a/drivers/iio/buffer/Makefile
+++ b/drivers/iio/buffer/Makefile
@@ -9,4 +9,5 @@ obj-$(CONFIG_IIO_BUFFER_DMA) += industrialio-buffer-dma.o
 obj-$(CONFIG_IIO_BUFFER_DMAENGINE) += industrialio-buffer-dmaengine.o
 obj-$(CONFIG_IIO_BUFFER_HW_CONSUMER) += industrialio-hw-consumer.o
 obj-$(CONFIG_IIO_TRIGGERED_BUFFER) += industrialio-triggered-buffer.o
+obj-$(CONFIG_IIO_HW_TRIGGERED_BUFFER) += industrialio-hw-triggered-buffer.o
 obj-$(CONFIG_IIO_KFIFO_BUF) += kfifo_buf.o
diff --git a/drivers/iio/buffer/industrialio-hw-triggered-buffer.c b/drivers/iio/buffer/industrialio-hw-triggered-buffer.c
new file mode 100644
index 000000000000..7a8a71066b0e
--- /dev/null
+++ b/drivers/iio/buffer/industrialio-hw-triggered-buffer.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2024 Analog Devices, Inc.
+ * Copyright (c) 2024 BayLibre, SAS
+ */
+
+#include <linux/auxiliary_bus.h>
+#include <linux/container_of.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/iio/hw_triggered_buffer_impl.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+
+static int iio_hw_triggered_buffer_match(struct device *dev, const void *match)
+{
+	return dev->parent == match;
+}
+
+static struct iio_hw_triggered_buffer_device
+*iio_hw_trigger_buffer_get(struct device *match)
+{
+	struct auxiliary_device *adev;
+
+	adev = auxiliary_find_device(NULL, match, iio_hw_triggered_buffer_match);
+	if (!adev)
+		return ERR_PTR(-ENOENT);
+
+	return container_of(adev, struct iio_hw_triggered_buffer_device, adev);
+}
+
+static void iio_hw_trigger_buffer_put(void *dev)
+{
+	put_device(dev);
+}
+
+/**
+ * devm_iio_hw_triggered_buffer_setup - Setup a hardware triggered buffer
+ * @dev:	Device for devm management
+ * @indio_dev:	An unconfigured/partially configured IIO device struct
+ * @match:	Device for matching the auxiliary bus device that provides the
+ *		interface to the hardware triggered buffer
+ * @ops:	Buffer setup functions to use for this IIO device
+ *
+ * Return: 0 on success, negative error code on failure.
+ *
+ * This function will search all registered hardware triggered buffers for one
+ * that matches the given indio_dev. If found, it will be used to setup both
+ * the trigger and the buffer on the indio_dev.
+ */
+int devm_iio_hw_triggered_buffer_setup(struct device *dev,
+				       struct iio_dev *indio_dev,
+				       struct device *match,
+				       const struct iio_buffer_setup_ops *ops)
+{
+	struct iio_hw_triggered_buffer_device *hw;
+	int ret;
+
+	hw = iio_hw_trigger_buffer_get(match);
+	if (IS_ERR(hw))
+		return PTR_ERR(hw);
+
+	ret = devm_add_action_or_reset(dev, iio_hw_trigger_buffer_put, &hw->adev.dev);
+	if (ret)
+		return ret;
+
+	indio_dev->modes |= INDIO_HW_BUFFER_TRIGGERED;
+	indio_dev->trig = iio_trigger_get(hw->trig);
+	indio_dev->setup_ops = ops;
+
+	return iio_device_attach_buffer(indio_dev, hw->buffer);
+}
+EXPORT_SYMBOL_GPL(devm_iio_hw_triggered_buffer_setup);
+
+static int iio_hw_trigger_buffer_probe(struct auxiliary_device *adev,
+				       const struct auxiliary_device_id *id)
+{
+	struct iio_hw_triggered_buffer_device *hw =
+		container_of(adev, struct iio_hw_triggered_buffer_device, adev);
+
+	if (!hw->buffer || !hw->trig)
+		return -EINVAL;
+
+	return 0;
+}
+
+static const struct auxiliary_device_id iio_hw_trigger_buffer_id_table[] = {
+	{ }
+};
+MODULE_DEVICE_TABLE(auxiliary, iio_hw_trigger_buffer_id_table);
+
+static struct auxiliary_driver iio_hw_trigger_buffer_driver = {
+	.driver = {
+		.name = "iio-hw-triggered-buffer",
+	},
+	.probe = iio_hw_trigger_buffer_probe,
+	.id_table = iio_hw_trigger_buffer_id_table,
+};
+module_auxiliary_driver(iio_hw_trigger_buffer_driver);
+
+MODULE_AUTHOR("David Lechner <dlechner@xxxxxxxxxxxx>");
+MODULE_DESCRIPTION("IIO helper functions for setting up hardware triggered buffers");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/iio/hw_triggered_buffer.h b/include/linux/iio/hw_triggered_buffer.h
new file mode 100644
index 000000000000..6bd8035f1b92
--- /dev/null
+++ b/include/linux/iio/hw_triggered_buffer.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_IIO_HW_TRIGGEREDED_BUFFER_H_
+#define _LINUX_IIO_HW_TRIGGEREDED_BUFFER_H_
+
+struct device;
+struct iio_dev;
+struct iio_buffer_setup_ops;
+
+int devm_iio_hw_triggered_buffer_setup(struct device *dev,
+				       struct iio_dev *indio_dev,
+				       struct device *match,
+				       const struct iio_buffer_setup_ops *ops);
+
+#endif /* _LINUX_IIO_HW_TRIGGEREDED_BUFFER_H_ */
diff --git a/include/linux/iio/hw_triggered_buffer_impl.h b/include/linux/iio/hw_triggered_buffer_impl.h
new file mode 100644
index 000000000000..d9a3ad2c8c24
--- /dev/null
+++ b/include/linux/iio/hw_triggered_buffer_impl.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_IIO_HW_TRIGGEREDED_BUFFER_IMPL_H_
+#define _LINUX_IIO_HW_TRIGGEREDED_BUFFER_IMPL_H_
+
+#include <linux/auxiliary_bus.h>
+
+struct iio_buffer;
+struct iio_trigger;
+
+struct iio_hw_triggered_buffer_device {
+	struct auxiliary_device adev;
+	struct iio_buffer *buffer;
+	struct iio_trigger *trig;
+};
+
+#endif /* _LINUX_IIO_HW_TRIGGEREDED_BUFFER_IMPL_H_ */

-- 
2.43.0