1/*
  2 * Virtual DMA channel support for DMAengine
  3 *
  4 * Copyright (C) 2012 Russell King
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2 as
  8 * published by the Free Software Foundation.
  9 */
 10#include <linux/device.h>
 11#include <linux/dmaengine.h>
 12#include <linux/module.h>
 13#include <linux/spinlock.h>
 14
 15#include "virt-dma.h"
 16
 17static struct virt_dma_desc *to_virt_desc(struct dma_async_tx_descriptor *tx)
 18{
 19	return container_of(tx, struct virt_dma_desc, tx);
 20}
 21
 22dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *tx)
 23{
 24	struct virt_dma_chan *vc = to_virt_chan(tx->chan);
 25	struct virt_dma_desc *vd = to_virt_desc(tx);
 26	unsigned long flags;
 27	dma_cookie_t cookie;
 28
 29	spin_lock_irqsave(&vc->lock, flags);
 30	cookie = dma_cookie_assign(tx);
 31
 32	list_move_tail(&vd->node, &vc->desc_submitted);
 33	spin_unlock_irqrestore(&vc->lock, flags);
 34
 35	dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: submitted\n",
 36		vc, vd, cookie);
 37
 38	return cookie;
 39}
 40EXPORT_SYMBOL_GPL(vchan_tx_submit);
 41
 42/**
 43 * vchan_tx_desc_free - free a reusable descriptor
 44 * @tx: the transfer
 45 *
 46 * This function frees a previously allocated reusable descriptor. The only
 47 * other way is to clear the DMA_CTRL_REUSE flag and submit one last time the
 48 * transfer.
 49 *
 50 * Returns 0 upon success
 51 */
 52int vchan_tx_desc_free(struct dma_async_tx_descriptor *tx)
 53{
 54	struct virt_dma_chan *vc = to_virt_chan(tx->chan);
 55	struct virt_dma_desc *vd = to_virt_desc(tx);
 56	unsigned long flags;
 57
 58	spin_lock_irqsave(&vc->lock, flags);
 59	list_del(&vd->node);
 60	spin_unlock_irqrestore(&vc->lock, flags);
 61
 62	dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: freeing\n",
 63		vc, vd, vd->tx.cookie);
 64	vc->desc_free(vd);
 65	return 0;
 66}
 67EXPORT_SYMBOL_GPL(vchan_tx_desc_free);
 68
 69struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *vc,
 70	dma_cookie_t cookie)
 71{
 72	struct virt_dma_desc *vd;
 73
 74	list_for_each_entry(vd, &vc->desc_issued, node)
 75		if (vd->tx.cookie == cookie)
 76			return vd;
 77
 78	return NULL;
 79}
 80EXPORT_SYMBOL_GPL(vchan_find_desc);
 81
 82/*
 83 * This tasklet handles the completion of a DMA descriptor by
 84 * calling its callback and freeing it.
 85 */
 86static void vchan_complete(unsigned long arg)
 87{
 88	struct virt_dma_chan *vc = (struct virt_dma_chan *)arg;
 89	struct virt_dma_desc *vd;
 90	dma_async_tx_callback cb = NULL;
 91	void *cb_data = NULL;
 92	LIST_HEAD(head);
 93
 94	spin_lock_irq(&vc->lock);
 95	list_splice_tail_init(&vc->desc_completed, &head);
 96	vd = vc->cyclic;
 97	if (vd) {
 98		vc->cyclic = NULL;
 99		cb = vd->tx.callback;
100		cb_data = vd->tx.callback_param;
101	}
102	spin_unlock_irq(&vc->lock);
103
104	if (cb)
105		cb(cb_data);
106
107	while (!list_empty(&head)) {
108		vd = list_first_entry(&head, struct virt_dma_desc, node);
109		cb = vd->tx.callback;
110		cb_data = vd->tx.callback_param;
111
112		list_del(&vd->node);
113		if (dmaengine_desc_test_reuse(&vd->tx))
114			list_add(&vd->node, &vc->desc_allocated);
115		else
116			vc->desc_free(vd);
117
118		if (cb)
119			cb(cb_data);
120	}
121}
122
123void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head)
124{
125	while (!list_empty(head)) {
126		struct virt_dma_desc *vd = list_first_entry(head,
127			struct virt_dma_desc, node);
128		if (dmaengine_desc_test_reuse(&vd->tx)) {
129			list_move_tail(&vd->node, &vc->desc_allocated);
130		} else {
131			dev_dbg(vc->chan.device->dev, "txd %p: freeing\n", vd);
132			list_del(&vd->node);
133			vc->desc_free(vd);
134		}
135	}
136}
137EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list);
138
139void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
140{
141	dma_cookie_init(&vc->chan);
142
143	spin_lock_init(&vc->lock);
144	INIT_LIST_HEAD(&vc->desc_allocated);
145	INIT_LIST_HEAD(&vc->desc_submitted);
146	INIT_LIST_HEAD(&vc->desc_issued);
147	INIT_LIST_HEAD(&vc->desc_completed);
148
149	tasklet_init(&vc->task, vchan_complete, (unsigned long)vc);
150
151	vc->chan.device = dmadev;
152	list_add_tail(&vc->chan.device_node, &dmadev->channels);
153}
154EXPORT_SYMBOL_GPL(vchan_init);
155
156MODULE_AUTHOR("Russell King");
157MODULE_LICENSE("GPL");