dmaengine: split out virtual channel DMA support from sa11x0 driver

Split the virtual slave channel DMA support from the sa11x0 driver so
this code can be shared with other slave DMA engine drivers.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 138 insertions, 0 deletions

diff --git a/drivers/dma/virt-dma.h b/drivers/dma/virt-dma.h
new file mode 100644
index 000000000000..825bb9623175
--- /dev/null
+++ b/drivers/dma/virt-dma.h
@@ -0,0 +1,138 @@
+/*
+ * 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;
+};
+
+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);
+
+/**
+ * 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_complete(&vd->tx);
+        dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
+                vd, vd->tx.cookie);
+        list_add_tail(&vd->node, &vc->desc_completed);
+
+        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