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 17 static 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 22 dma_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_add_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 } 40 EXPORT_SYMBOL_GPL(vchan_tx_submit); 41 42 struct virt_dma_desc *vchan_find_desc(struct virt_dma_chan *vc, 43 dma_cookie_t cookie) 44 { 45 struct virt_dma_desc *vd; 46 47 list_for_each_entry(vd, &vc->desc_issued, node) 48 if (vd->tx.cookie == cookie) 49 return vd; 50 51 return NULL; 52 } 53 EXPORT_SYMBOL_GPL(vchan_find_desc); 54 55 /* 56 * This tasklet handles the completion of a DMA descriptor by 57 * calling its callback and freeing it. 58 */ 59 static void vchan_complete(unsigned long arg) 60 { 61 struct virt_dma_chan *vc = (struct virt_dma_chan *)arg; 62 struct virt_dma_desc *vd; 63 dma_async_tx_callback cb = NULL; 64 void *cb_data = NULL; 65 LIST_HEAD(head); 66 67 spin_lock_irq(&vc->lock); 68 list_splice_tail_init(&vc->desc_completed, &head); 69 vd = vc->cyclic; 70 if (vd) { 71 vc->cyclic = NULL; 72 cb = vd->tx.callback; 73 cb_data = vd->tx.callback_param; 74 } 75 spin_unlock_irq(&vc->lock); 76 77 if (cb) 78 cb(cb_data); 79 80 while (!list_empty(&head)) { 81 vd = list_first_entry(&head, struct virt_dma_desc, node); 82 cb = vd->tx.callback; 83 cb_data = vd->tx.callback_param; 84 85 list_del(&vd->node); 86 87 vc->desc_free(vd); 88 89 if (cb) 90 cb(cb_data); 91 } 92 } 93 94 void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head) 95 { 96 while (!list_empty(head)) { 97 struct virt_dma_desc *vd = list_first_entry(head, 98 struct virt_dma_desc, node); 99 list_del(&vd->node); 100 dev_dbg(vc->chan.device->dev, "txd %p: freeing\n", vd); 101 vc->desc_free(vd); 102 } 103 } 104 EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list); 105 106 void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev) 107 { 108 dma_cookie_init(&vc->chan); 109 110 spin_lock_init(&vc->lock); 111 INIT_LIST_HEAD(&vc->desc_submitted); 112 INIT_LIST_HEAD(&vc->desc_issued); 113 INIT_LIST_HEAD(&vc->desc_completed); 114 115 tasklet_init(&vc->task, vchan_complete, (unsigned long)vc); 116 117 vc->chan.device = dmadev; 118 list_add_tail(&vc->chan.device_node, &dmadev->channels); 119 } 120 EXPORT_SYMBOL_GPL(vchan_init); 121 122 MODULE_AUTHOR("Russell King"); 123 MODULE_LICENSE("GPL"); 124