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571fa74034
Add support for cyclic DMA's periodic callbacks. Drivers are expected to call vchan_cyclic_callback() when a period has completed, which will schedule the tasklet to make the callback into the driver. As callbacks are made from tasklet context, it is important to realise that we don't guarantee a callback for each completed period, but for N completed periods where N may be greater than one. Tested-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
124 lines
2.9 KiB
C
124 lines
2.9 KiB
C
/*
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* Virtual DMA channel support for DMAengine
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*
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* Copyright (C) 2012 Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/device.h>
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#include <linux/dmaengine.h>
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include "virt-dma.h"
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static struct virt_dma_desc *to_virt_desc(struct dma_async_tx_descriptor *tx)
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{
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return container_of(tx, struct virt_dma_desc, tx);
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}
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dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *tx)
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{
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struct virt_dma_chan *vc = to_virt_chan(tx->chan);
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struct virt_dma_desc *vd = to_virt_desc(tx);
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unsigned long flags;
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dma_cookie_t cookie;
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spin_lock_irqsave(&vc->lock, flags);
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cookie = dma_cookie_assign(tx);
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list_add_tail(&vd->node, &vc->desc_submitted);
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spin_unlock_irqrestore(&vc->lock, flags);
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dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: submitted\n",
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vc, vd, cookie);
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return cookie;
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}
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EXPORT_SYMBOL_GPL(vchan_tx_submit);
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struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *vc,
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dma_cookie_t cookie)
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{
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struct virt_dma_desc *vd;
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list_for_each_entry(vd, &vc->desc_issued, node)
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if (vd->tx.cookie == cookie)
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return vd;
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return NULL;
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}
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EXPORT_SYMBOL_GPL(vchan_find_desc);
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/*
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* This tasklet handles the completion of a DMA descriptor by
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* calling its callback and freeing it.
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*/
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static void vchan_complete(unsigned long arg)
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{
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struct virt_dma_chan *vc = (struct virt_dma_chan *)arg;
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struct virt_dma_desc *vd;
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dma_async_tx_callback cb = NULL;
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void *cb_data = NULL;
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LIST_HEAD(head);
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spin_lock_irq(&vc->lock);
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list_splice_tail_init(&vc->desc_completed, &head);
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vd = vc->cyclic;
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if (vd) {
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vc->cyclic = NULL;
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cb = vd->tx.callback;
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cb_data = vd->tx.callback_param;
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}
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spin_unlock_irq(&vc->lock);
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if (cb)
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cb(cb_data);
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while (!list_empty(&head)) {
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vd = list_first_entry(&head, struct virt_dma_desc, node);
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cb = vd->tx.callback;
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cb_data = vd->tx.callback_param;
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list_del(&vd->node);
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vc->desc_free(vd);
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if (cb)
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cb(cb_data);
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}
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}
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void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head)
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{
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while (!list_empty(head)) {
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struct virt_dma_desc *vd = list_first_entry(head,
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struct virt_dma_desc, node);
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list_del(&vd->node);
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dev_dbg(vc->chan.device->dev, "txd %p: freeing\n", vd);
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vc->desc_free(vd);
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}
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}
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EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list);
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void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
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{
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dma_cookie_init(&vc->chan);
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spin_lock_init(&vc->lock);
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INIT_LIST_HEAD(&vc->desc_submitted);
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INIT_LIST_HEAD(&vc->desc_issued);
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INIT_LIST_HEAD(&vc->desc_completed);
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tasklet_init(&vc->task, vchan_complete, (unsigned long)vc);
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vc->chan.device = dmadev;
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list_add_tail(&vc->chan.device_node, &dmadev->channels);
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}
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EXPORT_SYMBOL_GPL(vchan_init);
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MODULE_AUTHOR("Russell King");
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MODULE_LICENSE("GPL");
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