diff options
Diffstat (limited to 'drivers/dma/virt-dma.c')
| -rw-r--r-- | drivers/dma/virt-dma.c | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/drivers/dma/virt-dma.c b/drivers/dma/virt-dma.c new file mode 100644 index 000000000..88ad8ed2a --- /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"); |