v4.19.13 snapshot.
diff --git a/drivers/dma/virt-dma.c b/drivers/dma/virt-dma.c
new file mode 100644
index 0000000..88ad8ed
--- /dev/null
+++ b/drivers/dma/virt-dma.c
@@ -0,0 +1,150 @@
+/*
+ * Virtual DMA channel support for DMAengine
+ *
+ * Copyright (C) 2012 Russell King
+ *
+ * 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/device.h>
+#include <linux/dmaengine.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+
+#include "virt-dma.h"
+
+static struct virt_dma_desc *to_virt_desc(struct dma_async_tx_descriptor *tx)
+{
+ return container_of(tx, struct virt_dma_desc, tx);
+}
+
+dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *tx)
+{
+ struct virt_dma_chan *vc = to_virt_chan(tx->chan);
+ struct virt_dma_desc *vd = to_virt_desc(tx);
+ unsigned long flags;
+ dma_cookie_t cookie;
+
+ spin_lock_irqsave(&vc->lock, flags);
+ cookie = dma_cookie_assign(tx);
+
+ list_move_tail(&vd->node, &vc->desc_submitted);
+ spin_unlock_irqrestore(&vc->lock, flags);
+
+ dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: submitted\n",
+ vc, vd, cookie);
+
+ return cookie;
+}
+EXPORT_SYMBOL_GPL(vchan_tx_submit);
+
+/**
+ * vchan_tx_desc_free - free a reusable descriptor
+ * @tx: the transfer
+ *
+ * This function frees a previously allocated reusable descriptor. The only
+ * other way is to clear the DMA_CTRL_REUSE flag and submit one last time the
+ * transfer.
+ *
+ * Returns 0 upon success
+ */
+int vchan_tx_desc_free(struct dma_async_tx_descriptor *tx)
+{
+ struct virt_dma_chan *vc = to_virt_chan(tx->chan);
+ struct virt_dma_desc *vd = to_virt_desc(tx);
+ unsigned long flags;
+
+ spin_lock_irqsave(&vc->lock, flags);
+ list_del(&vd->node);
+ spin_unlock_irqrestore(&vc->lock, flags);
+
+ dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: freeing\n",
+ vc, vd, vd->tx.cookie);
+ vc->desc_free(vd);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(vchan_tx_desc_free);
+
+struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *vc,
+ dma_cookie_t cookie)
+{
+ struct virt_dma_desc *vd;
+
+ list_for_each_entry(vd, &vc->desc_issued, node)
+ if (vd->tx.cookie == cookie)
+ return vd;
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(vchan_find_desc);
+
+/*
+ * This tasklet handles the completion of a DMA descriptor by
+ * calling its callback and freeing it.
+ */
+static void vchan_complete(unsigned long arg)
+{
+ struct virt_dma_chan *vc = (struct virt_dma_chan *)arg;
+ struct virt_dma_desc *vd, *_vd;
+ struct dmaengine_desc_callback cb;
+ LIST_HEAD(head);
+
+ spin_lock_irq(&vc->lock);
+ list_splice_tail_init(&vc->desc_completed, &head);
+ vd = vc->cyclic;
+ if (vd) {
+ vc->cyclic = NULL;
+ dmaengine_desc_get_callback(&vd->tx, &cb);
+ } else {
+ memset(&cb, 0, sizeof(cb));
+ }
+ spin_unlock_irq(&vc->lock);
+
+ dmaengine_desc_callback_invoke(&cb, NULL);
+
+ list_for_each_entry_safe(vd, _vd, &head, node) {
+ dmaengine_desc_get_callback(&vd->tx, &cb);
+
+ list_del(&vd->node);
+ vchan_vdesc_fini(vd);
+
+ dmaengine_desc_callback_invoke(&cb, NULL);
+ }
+}
+
+void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head)
+{
+ struct virt_dma_desc *vd, *_vd;
+
+ list_for_each_entry_safe(vd, _vd, head, node) {
+ if (dmaengine_desc_test_reuse(&vd->tx)) {
+ list_move_tail(&vd->node, &vc->desc_allocated);
+ } else {
+ dev_dbg(vc->chan.device->dev, "txd %p: freeing\n", vd);
+ list_del(&vd->node);
+ vc->desc_free(vd);
+ }
+ }
+}
+EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list);
+
+void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
+{
+ dma_cookie_init(&vc->chan);
+
+ spin_lock_init(&vc->lock);
+ INIT_LIST_HEAD(&vc->desc_allocated);
+ INIT_LIST_HEAD(&vc->desc_submitted);
+ INIT_LIST_HEAD(&vc->desc_issued);
+ INIT_LIST_HEAD(&vc->desc_completed);
+
+ tasklet_init(&vc->task, vchan_complete, (unsigned long)vc);
+
+ vc->chan.device = dmadev;
+ list_add_tail(&vc->chan.device_node, &dmadev->channels);
+}
+EXPORT_SYMBOL_GPL(vchan_init);
+
+MODULE_AUTHOR("Russell King");
+MODULE_LICENSE("GPL");