v4.19.13 snapshot.
diff --git a/drivers/iio/buffer/industrialio-buffer-cb.c b/drivers/iio/buffer/industrialio-buffer-cb.c
new file mode 100644
index 0000000..ea63c83
--- /dev/null
+++ b/drivers/iio/buffer/industrialio-buffer-cb.c
@@ -0,0 +1,154 @@
+/* The industrial I/O callback buffer
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer_impl.h>
+#include <linux/iio/consumer.h>
+
+struct iio_cb_buffer {
+ struct iio_buffer buffer;
+ int (*cb)(const void *data, void *private);
+ void *private;
+ struct iio_channel *channels;
+ struct iio_dev *indio_dev;
+};
+
+static struct iio_cb_buffer *buffer_to_cb_buffer(struct iio_buffer *buffer)
+{
+ return container_of(buffer, struct iio_cb_buffer, buffer);
+}
+
+static int iio_buffer_cb_store_to(struct iio_buffer *buffer, const void *data)
+{
+ struct iio_cb_buffer *cb_buff = buffer_to_cb_buffer(buffer);
+ return cb_buff->cb(data, cb_buff->private);
+}
+
+static void iio_buffer_cb_release(struct iio_buffer *buffer)
+{
+ struct iio_cb_buffer *cb_buff = buffer_to_cb_buffer(buffer);
+ kfree(cb_buff->buffer.scan_mask);
+ kfree(cb_buff);
+}
+
+static const struct iio_buffer_access_funcs iio_cb_access = {
+ .store_to = &iio_buffer_cb_store_to,
+ .release = &iio_buffer_cb_release,
+
+ .modes = INDIO_BUFFER_SOFTWARE | INDIO_BUFFER_TRIGGERED,
+};
+
+struct iio_cb_buffer *iio_channel_get_all_cb(struct device *dev,
+ int (*cb)(const void *data,
+ void *private),
+ void *private)
+{
+ int ret;
+ struct iio_cb_buffer *cb_buff;
+ struct iio_channel *chan;
+
+ cb_buff = kzalloc(sizeof(*cb_buff), GFP_KERNEL);
+ if (cb_buff == NULL)
+ return ERR_PTR(-ENOMEM);
+
+ iio_buffer_init(&cb_buff->buffer);
+
+ cb_buff->private = private;
+ cb_buff->cb = cb;
+ cb_buff->buffer.access = &iio_cb_access;
+ INIT_LIST_HEAD(&cb_buff->buffer.demux_list);
+
+ cb_buff->channels = iio_channel_get_all(dev);
+ if (IS_ERR(cb_buff->channels)) {
+ ret = PTR_ERR(cb_buff->channels);
+ goto error_free_cb_buff;
+ }
+
+ cb_buff->indio_dev = cb_buff->channels[0].indio_dev;
+ cb_buff->buffer.scan_mask
+ = kcalloc(BITS_TO_LONGS(cb_buff->indio_dev->masklength),
+ sizeof(long), GFP_KERNEL);
+ if (cb_buff->buffer.scan_mask == NULL) {
+ ret = -ENOMEM;
+ goto error_release_channels;
+ }
+ chan = &cb_buff->channels[0];
+ while (chan->indio_dev) {
+ if (chan->indio_dev != cb_buff->indio_dev) {
+ ret = -EINVAL;
+ goto error_free_scan_mask;
+ }
+ set_bit(chan->channel->scan_index,
+ cb_buff->buffer.scan_mask);
+ chan++;
+ }
+
+ return cb_buff;
+
+error_free_scan_mask:
+ kfree(cb_buff->buffer.scan_mask);
+error_release_channels:
+ iio_channel_release_all(cb_buff->channels);
+error_free_cb_buff:
+ kfree(cb_buff);
+ return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(iio_channel_get_all_cb);
+
+int iio_channel_cb_set_buffer_watermark(struct iio_cb_buffer *cb_buff,
+ size_t watermark)
+{
+ if (!watermark)
+ return -EINVAL;
+ cb_buff->buffer.watermark = watermark;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(iio_channel_cb_set_buffer_watermark);
+
+int iio_channel_start_all_cb(struct iio_cb_buffer *cb_buff)
+{
+ return iio_update_buffers(cb_buff->indio_dev, &cb_buff->buffer,
+ NULL);
+}
+EXPORT_SYMBOL_GPL(iio_channel_start_all_cb);
+
+void iio_channel_stop_all_cb(struct iio_cb_buffer *cb_buff)
+{
+ iio_update_buffers(cb_buff->indio_dev, NULL, &cb_buff->buffer);
+}
+EXPORT_SYMBOL_GPL(iio_channel_stop_all_cb);
+
+void iio_channel_release_all_cb(struct iio_cb_buffer *cb_buff)
+{
+ iio_channel_release_all(cb_buff->channels);
+ iio_buffer_put(&cb_buff->buffer);
+}
+EXPORT_SYMBOL_GPL(iio_channel_release_all_cb);
+
+struct iio_channel
+*iio_channel_cb_get_channels(const struct iio_cb_buffer *cb_buffer)
+{
+ return cb_buffer->channels;
+}
+EXPORT_SYMBOL_GPL(iio_channel_cb_get_channels);
+
+struct iio_dev
+*iio_channel_cb_get_iio_dev(const struct iio_cb_buffer *cb_buffer)
+{
+ return cb_buffer->indio_dev;
+}
+EXPORT_SYMBOL_GPL(iio_channel_cb_get_iio_dev);
+
+MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
+MODULE_DESCRIPTION("Industrial I/O callback buffer");
+MODULE_LICENSE("GPL");