iio: Add hardware consumer buffer support

Hardware consumer interface can be used when one IIO device has
a direct connection to another device in hardware.

Signed-off-by: Lars-Peter Clausen <[e-mail]>
Signed-off-by: Arnaud Pouliquen <[e-mail]>
Reviewed-by: Jonathan Cameron <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

drivers/iio/buffer/Kconfig

···
 
 	  Should be selected by drivers that want to use this functionality.
 
+config IIO_BUFFER_HW_CONSUMER
+	tristate "Industrial I/O HW buffering"
+	help
+	  Provides a way to bonding when an IIO device has a direct connection
+	  to another device in hardware. In this case buffers for data transfers
+	  are handled by hardware.
+
+	  Should be selected by drivers that want to use the generic Hw consumer
+	  interface.
+
 config IIO_KFIFO_BUF
 	tristate "Industrial I/O buffering based on kfifo"
 	help

drivers/iio/buffer/Makefile

···
 obj-$(CONFIG_IIO_BUFFER_CB) += industrialio-buffer-cb.o
 obj-$(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_KFIFO_BUF) += kfifo_buf.o

drivers/iio/buffer/industrialio-hw-consumer.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2017 Analog Devices Inc.
+ *  Author: Lars-Peter Clausen <[e-mail]>
+ */
+
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/consumer.h>
+#include <linux/iio/hw-consumer.h>
+#include <linux/iio/buffer_impl.h>
+
+/**
+ * struct iio_hw_consumer - IIO hw consumer block
+ * @buffers: hardware buffers list head.
+ * @channels: IIO provider channels.
+ */
+struct iio_hw_consumer {
+	struct list_head buffers;
+	struct iio_channel *channels;
+};
+
+struct hw_consumer_buffer {
+	struct list_head head;
+	struct iio_dev *indio_dev;
+	struct iio_buffer buffer;
+	long scan_mask[];
+};
+
+static struct hw_consumer_buffer *iio_buffer_to_hw_consumer_buffer(
+	struct iio_buffer *buffer)
+{
+	return container_of(buffer, struct hw_consumer_buffer, buffer);
+}
+
+static void iio_hw_buf_release(struct iio_buffer *buffer)
+{
+	struct hw_consumer_buffer *hw_buf =
+		iio_buffer_to_hw_consumer_buffer(buffer);
+	kfree(hw_buf);
+}
+
+static const struct iio_buffer_access_funcs iio_hw_buf_access = {
+	.release = &iio_hw_buf_release,
+	.modes = INDIO_BUFFER_HARDWARE,
+};
+
+static struct hw_consumer_buffer *iio_hw_consumer_get_buffer(
+	struct iio_hw_consumer *hwc, struct iio_dev *indio_dev)
+{
+	size_t mask_size = BITS_TO_LONGS(indio_dev->masklength) * sizeof(long);
+	struct hw_consumer_buffer *buf;
+
+	list_for_each_entry(buf, &hwc->buffers, head) {
+		if (buf->indio_dev == indio_dev)
+			return buf;
+	}
+
+	buf = kzalloc(sizeof(*buf) + mask_size, GFP_KERNEL);
+	if (!buf)
+		return NULL;
+
+	buf->buffer.access = &iio_hw_buf_access;
+	buf->indio_dev = indio_dev;
+	buf->buffer.scan_mask = buf->scan_mask;
+
+	iio_buffer_init(&buf->buffer);
+	list_add_tail(&buf->head, &hwc->buffers);
+
+	return buf;
+}
+
+/**
+ * iio_hw_consumer_alloc() - Allocate IIO hardware consumer
+ * @dev: Pointer to consumer device.
+ *
+ * Returns a valid iio_hw_consumer on success or a ERR_PTR() on failure.
+ */
+struct iio_hw_consumer *iio_hw_consumer_alloc(struct device *dev)
+{
+	struct hw_consumer_buffer *buf;
+	struct iio_hw_consumer *hwc;
+	struct iio_channel *chan;
+	int ret;
+
+	hwc = kzalloc(sizeof(*hwc), GFP_KERNEL);
+	if (!hwc)
+		return ERR_PTR(-ENOMEM);
+
+	INIT_LIST_HEAD(&hwc->buffers);
+
+	hwc->channels = iio_channel_get_all(dev);
+	if (IS_ERR(hwc->channels)) {
+		ret = PTR_ERR(hwc->channels);
+		goto err_free_hwc;
+	}
+
+	chan = &hwc->channels[0];
+	while (chan->indio_dev) {
+		buf = iio_hw_consumer_get_buffer(hwc, chan->indio_dev);
+		if (!buf) {
+			ret = -ENOMEM;
+			goto err_put_buffers;
+		}
+		set_bit(chan->channel->scan_index, buf->buffer.scan_mask);
+		chan++;
+	}
+
+	return hwc;
+
+err_put_buffers:
+	list_for_each_entry(buf, &hwc->buffers, head)
+		iio_buffer_put(&buf->buffer);
+	iio_channel_release_all(hwc->channels);
+err_free_hwc:
+	kfree(hwc);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(iio_hw_consumer_alloc);
+
+/**
+ * iio_hw_consumer_free() - Free IIO hardware consumer
+ * @hwc: hw consumer to free.
+ */
+void iio_hw_consumer_free(struct iio_hw_consumer *hwc)
+{
+	struct hw_consumer_buffer *buf, *n;
+
+	iio_channel_release_all(hwc->channels);
+	list_for_each_entry_safe(buf, n, &hwc->buffers, head)
+		iio_buffer_put(&buf->buffer);
+	kfree(hwc);
+}
+EXPORT_SYMBOL_GPL(iio_hw_consumer_free);
+
+/**
+ * iio_hw_consumer_enable() - Enable IIO hardware consumer
+ * @hwc: iio_hw_consumer to enable.
+ *
+ * Returns 0 on success.
+ */
+int iio_hw_consumer_enable(struct iio_hw_consumer *hwc)
+{
+	struct hw_consumer_buffer *buf;
+	int ret;
+
+	list_for_each_entry(buf, &hwc->buffers, head) {
+		ret = iio_update_buffers(buf->indio_dev, &buf->buffer, NULL);
+		if (ret)
+			goto err_disable_buffers;
+	}
+
+	return 0;
+
+err_disable_buffers:
+	list_for_each_entry_continue_reverse(buf, &hwc->buffers, head)
+		iio_update_buffers(buf->indio_dev, NULL, &buf->buffer);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_hw_consumer_enable);
+
+/**
+ * iio_hw_consumer_disable() - Disable IIO hardware consumer
+ * @hwc: iio_hw_consumer to disable.
+ */
+void iio_hw_consumer_disable(struct iio_hw_consumer *hwc)
+{
+	struct hw_consumer_buffer *buf;
+
+	list_for_each_entry(buf, &hwc->buffers, head)
+		iio_update_buffers(buf->indio_dev, NULL, &buf->buffer);
+}
+EXPORT_SYMBOL_GPL(iio_hw_consumer_disable);
+
+MODULE_AUTHOR("Lars-Peter Clausen <[e-mail]>");
+MODULE_DESCRIPTION("Hardware consumer buffer the IIO framework");
+MODULE_LICENSE("GPL v2");

include/linux/iio/hw-consumer.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Industrial I/O in kernel hardware consumer interface
+ *
+ * Copyright 2017 Analog Devices Inc.
+ *  Author: Lars-Peter Clausen <[e-mail]>
+ */
+
+#ifndef LINUX_IIO_HW_CONSUMER_H
+#define LINUX_IIO_HW_CONSUMER_H
+
+struct iio_hw_consumer;
+
+struct iio_hw_consumer *iio_hw_consumer_alloc(struct device *dev);
+void iio_hw_consumer_free(struct iio_hw_consumer *hwc);
+int iio_hw_consumer_enable(struct iio_hw_consumer *hwc);
+void iio_hw_consumer_disable(struct iio_hw_consumer *hwc);
+
+#endif