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 <lars@metafoo.de>
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

4 files changed, 211 insertions, 0 deletions

diff --git a/drivers/iio/buffer/Kconfig b/drivers/iio/buffer/Kconfig
index 4ffd3db7817f..338774cba19b 100644
--- a/drivers/iio/buffer/Kconfig
+++ b/drivers/iio/buffer/Kconfig
@@ -29,6 +29,16 @@ config IIO_BUFFER_DMAENGINE
 
           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
diff --git a/drivers/iio/buffer/Makefile b/drivers/iio/buffer/Makefile
index 95f9f41c58b7..1403eb2f9409 100644
--- a/drivers/iio/buffer/Makefile
+++ b/drivers/iio/buffer/Makefile
@@ -7,5 +7,6 @@
 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
diff --git a/drivers/iio/buffer/industrialio-hw-consumer.c b/drivers/iio/buffer/industrialio-hw-consumer.c
new file mode 100644
index 000000000000..993ecdcdab64
--- /dev/null
+++ b/drivers/iio/buffer/industrialio-hw-consumer.c
@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2017 Analog Devices Inc.
+ *  Author: Lars-Peter Clausen <lars@metafoo.de>
+ */
+
+#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 <lars@metafoo.de>");
+MODULE_DESCRIPTION("Hardware consumer buffer the IIO framework");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/iio/hw-consumer.h b/include/linux/iio/hw-consumer.h
new file mode 100644
index 000000000000..db8c00b9c7a5
--- /dev/null
+++ b/include/linux/iio/hw-consumer.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Industrial I/O in kernel hardware consumer interface
+ *
+ * Copyright 2017 Analog Devices Inc.
+ *  Author: Lars-Peter Clausen <lars@metafoo.de>
+ */
+
+#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