1 files changed, 154 insertions, 0 deletions

diff --git a/kernel/drivers/dma/virt-dma.h b/kernel/drivers/dma/virt-dma.h
new file mode 100644
index 000000000..181b95267
--- /dev/null
+++ b/kernel/drivers/dma/virt-dma.h
@@ -0,0 +1,154 @@
+/*
+ * 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.
+ */
+#ifndef VIRT_DMA_H
+#define VIRT_DMA_H
+
+#include <linux/dmaengine.h>
+#include <linux/interrupt.h>
+
+#include "dmaengine.h"
+
+struct virt_dma_desc {
+	struct dma_async_tx_descriptor tx;
+	/* protected by vc.lock */
+	struct list_head node;
+};
+
+struct virt_dma_chan {
+	struct dma_chan	chan;
+	struct tasklet_struct task;
+	void (*desc_free)(struct virt_dma_desc *);
+
+	spinlock_t lock;
+
+	/* protected by vc.lock */
+	struct list_head desc_submitted;
+	struct list_head desc_issued;
+	struct list_head desc_completed;
+
+	struct virt_dma_desc *cyclic;
+};
+
+static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
+{
+	return container_of(chan, struct virt_dma_chan, chan);
+}
+
+void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
+void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
+struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *, dma_cookie_t);
+
+/**
+ * vchan_tx_prep - prepare a descriptor
+ * vc: virtual channel allocating this descriptor
+ * vd: virtual descriptor to prepare
+ * tx_flags: flags argument passed in to prepare function
+ */
+static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan *vc,
+	struct virt_dma_desc *vd, unsigned long tx_flags)
+{
+	extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
+
+	dma_async_tx_descriptor_init(&vd->tx, &vc->chan);
+	vd->tx.flags = tx_flags;
+	vd->tx.tx_submit = vchan_tx_submit;
+
+	return &vd->tx;
+}
+
+/**
+ * vchan_issue_pending - move submitted descriptors to issued list
+ * vc: virtual channel to update
+ *
+ * vc.lock must be held by caller
+ */
+static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
+{
+	list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
+	return !list_empty(&vc->desc_issued);
+}
+
+/**
+ * vchan_cookie_complete - report completion of a descriptor
+ * vd: virtual descriptor to update
+ *
+ * vc.lock must be held by caller
+ */
+static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
+{
+	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
+	dma_cookie_t cookie;
+
+	cookie = vd->tx.cookie;
+	dma_cookie_complete(&vd->tx);
+	dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
+		 vd, cookie);
+	list_add_tail(&vd->node, &vc->desc_completed);
+
+	tasklet_schedule(&vc->task);
+}
+
+/**
+ * vchan_cyclic_callback - report the completion of a period
+ * vd: virtual descriptor
+ */
+static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
+{
+	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
+
+	vc->cyclic = vd;
+	tasklet_schedule(&vc->task);
+}
+
+/**
+ * vchan_next_desc - peek at the next descriptor to be processed
+ * vc: virtual channel to obtain descriptor from
+ *
+ * vc.lock must be held by caller
+ */
+static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
+{
+	if (list_empty(&vc->desc_issued))
+		return NULL;
+
+	return list_first_entry(&vc->desc_issued, struct virt_dma_desc, node);
+}
+
+/**
+ * vchan_get_all_descriptors - obtain all submitted and issued descriptors
+ * vc: virtual channel to get descriptors from
+ * head: list of descriptors found
+ *
+ * vc.lock must be held by caller
+ *
+ * Removes all submitted and issued descriptors from internal lists, and
+ * provides a list of all descriptors found
+ */
+static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
+	struct list_head *head)
+{
+	list_splice_tail_init(&vc->desc_submitted, head);
+	list_splice_tail_init(&vc->desc_issued, head);
+	list_splice_tail_init(&vc->desc_completed, head);
+}
+
+static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
+{
+	unsigned long flags;
+	LIST_HEAD(head);
+
+	spin_lock_irqsave(&vc->lock, flags);
+	vchan_get_all_descriptors(vc, &head);
+	spin_unlock_irqrestore(&vc->lock, flags);
+
+	vchan_dma_desc_free_list(vc, &head);
+}
+
+#endif