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_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 } 40 EXPORT_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 */ 52 int 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 } 67 EXPORT_SYMBOL_GPL(vchan_tx_desc_free); 68 69 struct 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 } 80 EXPORT_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 */ 86 static 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 struct dmaengine_desc_callback cb; 91 LIST_HEAD(head); 92 93 spin_lock_irq(&vc->lock); 94 list_splice_tail_init(&vc->desc_completed, &head); 95 vd = vc->cyclic; 96 if (vd) { 97 vc->cyclic = NULL; 98 dmaengine_desc_get_callback(&vd->tx, &cb); 99 } else { 100 memset(&cb, 0, sizeof(cb)); 101 } 102 spin_unlock_irq(&vc->lock); 103 104 dmaengine_desc_callback_invoke(&cb, NULL); 105 106 while (!list_empty(&head)) { 107 vd = list_first_entry(&head, struct virt_dma_desc, node); 108 dmaengine_desc_get_callback(&vd->tx, &cb); 109 110 list_del(&vd->node); 111 if (dmaengine_desc_test_reuse(&vd->tx)) 112 list_add(&vd->node, &vc->desc_allocated); 113 else 114 vc->desc_free(vd); 115 116 dmaengine_desc_callback_invoke(&cb, NULL); 117 } 118 } 119 120 void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head) 121 { 122 while (!list_empty(head)) { 123 struct virt_dma_desc *vd = list_first_entry(head, 124 struct virt_dma_desc, node); 125 if (dmaengine_desc_test_reuse(&vd->tx)) { 126 list_move_tail(&vd->node, &vc->desc_allocated); 127 } else { 128 dev_dbg(vc->chan.device->dev, "txd %p: freeing\n", vd); 129 list_del(&vd->node); 130 vc->desc_free(vd); 131 } 132 } 133 } 134 EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list); 135 136 void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev) 137 { 138 dma_cookie_init(&vc->chan); 139 140 spin_lock_init(&vc->lock); 141 INIT_LIST_HEAD(&vc->desc_allocated); 142 INIT_LIST_HEAD(&vc->desc_submitted); 143 INIT_LIST_HEAD(&vc->desc_issued); 144 INIT_LIST_HEAD(&vc->desc_completed); 145 146 tasklet_init(&vc->task, vchan_complete, (unsigned long)vc); 147 148 vc->chan.device = dmadev; 149 list_add_tail(&vc->chan.device_node, &dmadev->channels); 150 } 151 EXPORT_SYMBOL_GPL(vchan_init); 152 153 MODULE_AUTHOR("Russell King"); 154 MODULE_LICENSE("GPL"); 155