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 dma_async_tx_callback cb = NULL; 91 void *cb_data = NULL; 92 LIST_HEAD(head); 93 94 spin_lock_irq(&vc->lock); 95 list_splice_tail_init(&vc->desc_completed, &head); 96 vd = vc->cyclic; 97 if (vd) { 98 vc->cyclic = NULL; 99 cb = vd->tx.callback; 100 cb_data = vd->tx.callback_param; 101 } 102 spin_unlock_irq(&vc->lock); 103 104 if (cb) 105 cb(cb_data); 106 107 while (!list_empty(&head)) { 108 vd = list_first_entry(&head, struct virt_dma_desc, node); 109 cb = vd->tx.callback; 110 cb_data = vd->tx.callback_param; 111 112 list_del(&vd->node); 113 if (dmaengine_desc_test_reuse(&vd->tx)) 114 list_add(&vd->node, &vc->desc_allocated); 115 else 116 vc->desc_free(vd); 117 118 if (cb) 119 cb(cb_data); 120 } 121 } 122 123 void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head) 124 { 125 while (!list_empty(head)) { 126 struct virt_dma_desc *vd = list_first_entry(head, 127 struct virt_dma_desc, node); 128 if (dmaengine_desc_test_reuse(&vd->tx)) { 129 list_move_tail(&vd->node, &vc->desc_allocated); 130 } else { 131 dev_dbg(vc->chan.device->dev, "txd %p: freeing\n", vd); 132 list_del(&vd->node); 133 vc->desc_free(vd); 134 } 135 } 136 } 137 EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list); 138 139 void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev) 140 { 141 dma_cookie_init(&vc->chan); 142 143 spin_lock_init(&vc->lock); 144 INIT_LIST_HEAD(&vc->desc_allocated); 145 INIT_LIST_HEAD(&vc->desc_submitted); 146 INIT_LIST_HEAD(&vc->desc_issued); 147 INIT_LIST_HEAD(&vc->desc_completed); 148 149 tasklet_init(&vc->task, vchan_complete, (unsigned long)vc); 150 151 vc->chan.device = dmadev; 152 list_add_tail(&vc->chan.device_node, &dmadev->channels); 153 } 154 EXPORT_SYMBOL_GPL(vchan_init); 155 156 MODULE_AUTHOR("Russell King"); 157 MODULE_LICENSE("GPL"); 158