详解ARM的AMBA设备中的DMA设备PL08X的Linux驱动

第 2 章 ARM的PL08X的代码的详细解析 第二部分

/*
 *  Might take too long to do all at once
 *  if so - free some then hand it off
 */
void pl08x_memrelease(void)
{
	struct pl08x_txd *local_txd, *next;
	unsigned long flags;
	int chan;

	for (chan = 0; chan < MAX_DMA_CHANNELS; chan++) {

		list_for_each_entry_safe(local_txd, next, &pd.chanwrap[chan]->release_list, txd_list)
		{
			spin_lock_irqsave(&pd.lock, flags);
			if (!local_txd)
				dev_err(&pd.dmac->dev,
					"%s - no descriptor\n",	__func__);

			if (local_txd->tx.callback) {
				((struct pl08x_callback_param *)
					local_txd->tx.callback_param)->act =
						PL08X_RELEASE;
				local_txd->tx.callback(
					local_txd->tx.callback_param);
			}

			list_del(&local_txd->txd_list);
			dma_pool_free(pd.pool, local_txd->llis_va,
				local_txd->llis_bus);

			/*
			 * p/m data not mapped - uses coherent or io mem
			 */
			if (!local_txd->slave) {
				dma_unmap_single(dmac.dev,
					local_txd->srcbus.addr, local_txd->len,
						local_txd->srcdir);

				dma_unmap_single(dmac.dev,
					local_txd->dstbus.addr, local_txd->len,
						local_txd->dstdir);
			}
			kfree(local_txd);
			spin_unlock_irqrestore(&pd.lock, flags);
		}
	}
	pd.pool_ctr = 0;
}