drivers/dma/virt-dma.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Virtual DMA channel support for DMAengine
0004  *
0005  * Copyright (C) 2012 Russell King
0006  */
0007 #include <linux/device.h>
0008 #include <linux/dmaengine.h>
0009 #include <linux/module.h>
0010 #include <linux/spinlock.h>
0011
0012 #include "virt-dma.h"
0013
0014 static struct virt_dma_desc *to_virt_desc(struct dma_async_tx_descriptor *tx)
0015 {
0016     return container_of(tx, struct virt_dma_desc, tx);
0017 }
0018
0019 dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *tx)
0020 {
0021     struct virt_dma_chan *vc = to_virt_chan(tx->chan);
0022     struct virt_dma_desc *vd = to_virt_desc(tx);
0023     unsigned long flags;
0024     dma_cookie_t cookie;
0025
0026     spin_lock_irqsave(&vc->lock, flags);
0027     cookie = dma_cookie_assign(tx);
0028
0029     list_move_tail(&vd->node, &vc->desc_submitted);
0030     spin_unlock_irqrestore(&vc->lock, flags);
0031
0032     dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: submitted\n",
0033         vc, vd, cookie);
0034
0035     return cookie;
0036 }
0037 EXPORT_SYMBOL_GPL(vchan_tx_submit);
0038
0039 /**
0040  * vchan_tx_desc_free - free a reusable descriptor
0041  * @tx: the transfer
0042  *
0043  * This function frees a previously allocated reusable descriptor. The only
0044  * other way is to clear the DMA_CTRL_REUSE flag and submit one last time the
0045  * transfer.
0046  *
0047  * Returns 0 upon success
0048  */
0049 int vchan_tx_desc_free(struct dma_async_tx_descriptor *tx)
0050 {
0051     struct virt_dma_chan *vc = to_virt_chan(tx->chan);
0052     struct virt_dma_desc *vd = to_virt_desc(tx);
0053     unsigned long flags;
0054
0055     spin_lock_irqsave(&vc->lock, flags);
0056     list_del(&vd->node);
0057     spin_unlock_irqrestore(&vc->lock, flags);
0058
0059     dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: freeing\n",
0060         vc, vd, vd->tx.cookie);
0061     vc->desc_free(vd);
0062     return 0;
0063 }
0064 EXPORT_SYMBOL_GPL(vchan_tx_desc_free);
0065
0066 struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *vc,
0067     dma_cookie_t cookie)
0068 {
0069     struct virt_dma_desc *vd;
0070
0071     list_for_each_entry(vd, &vc->desc_issued, node)
0072         if (vd->tx.cookie == cookie)
0073             return vd;
0074
0075     return NULL;
0076 }
0077 EXPORT_SYMBOL_GPL(vchan_find_desc);
0078
0079 /*
0080  * This tasklet handles the completion of a DMA descriptor by
0081  * calling its callback and freeing it.
0082  */
0083 static void vchan_complete(struct tasklet_struct *t)
0084 {
0085     struct virt_dma_chan *vc = from_tasklet(vc, t, task);
0086     struct virt_dma_desc *vd, *_vd;
0087     struct dmaengine_desc_callback cb;
0088     LIST_HEAD(head);
0089
0090     spin_lock_irq(&vc->lock);
0091     list_splice_tail_init(&vc->desc_completed, &head);
0092     vd = vc->cyclic;
0093     if (vd) {
0094         vc->cyclic = NULL;
0095         dmaengine_desc_get_callback(&vd->tx, &cb);
0096     } else {
0097         memset(&cb, 0, sizeof(cb));
0098     }
0099     spin_unlock_irq(&vc->lock);
0100
0101     dmaengine_desc_callback_invoke(&cb, &vd->tx_result);
0102
0103     list_for_each_entry_safe(vd, _vd, &head, node) {
0104         dmaengine_desc_get_callback(&vd->tx, &cb);
0105
0106         list_del(&vd->node);
0107         dmaengine_desc_callback_invoke(&cb, &vd->tx_result);
0108         vchan_vdesc_fini(vd);
0109     }
0110 }
0111
0112 void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head)
0113 {
0114     struct virt_dma_desc *vd, *_vd;
0115
0116     list_for_each_entry_safe(vd, _vd, head, node) {
0117         list_del(&vd->node);
0118         vchan_vdesc_fini(vd);
0119     }
0120 }
0121 EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list);
0122
0123 void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
0124 {
0125     dma_cookie_init(&vc->chan);
0126
0127     spin_lock_init(&vc->lock);
0128     INIT_LIST_HEAD(&vc->desc_allocated);
0129     INIT_LIST_HEAD(&vc->desc_submitted);
0130     INIT_LIST_HEAD(&vc->desc_issued);
0131     INIT_LIST_HEAD(&vc->desc_completed);
0132     INIT_LIST_HEAD(&vc->desc_terminated);
0133
0134     tasklet_setup(&vc->task, vchan_complete);
0135
0136     vc->chan.device = dmadev;
0137     list_add_tail(&vc->chan.device_node, &dmadev->channels);
0138 }
0139 EXPORT_SYMBOL_GPL(vchan_init);
0140
0141 MODULE_AUTHOR("Russell King");
0142 MODULE_LICENSE("GPL");