示例#1
0
static int __init example_init(void)
{
	int			i;
	unsigned int		ret;
	unsigned int		nents;
	struct scatterlist	sg[10];

	printk(KERN_INFO "DMA fifo test start\n");

	if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
		printk(KERN_WARNING "error kfifo_alloc\n");
		return -ENOMEM;
	}

	printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));

	kfifo_in(&fifo, "test", 4);

	for (i = 0; i != 9; i++)
		kfifo_put(&fifo, i);

	/* kick away first byte */
	kfifo_skip(&fifo);

	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));

	/*
	 * Configure the kfifo buffer to receive data from DMA input.
	 *
	 *  .--------------------------------------.
	 *  | 0 | 1 | 2 | ... | 12 | 13 | ... | 31 |
	 *  |---|------------------|---------------|
	 *   \_/ \________________/ \_____________/
	 *    \          \                  \
	 *     \          \_allocated data   \
	 *      \_*free space*                \_*free space*
	 *
	 * We need two different SG entries: one for the free space area at the
	 * end of the kfifo buffer (19 bytes) and another for the first free
	 * byte at the beginning, after the kfifo_skip().
	 */
	sg_init_table(sg, ARRAY_SIZE(sg));
	nents = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
	printk(KERN_INFO "DMA sgl entries: %d\n", nents);
	if (!nents) {
		/* fifo is full and no sgl was created */
		printk(KERN_WARNING "error kfifo_dma_in_prepare\n");
		return -EIO;
	}

	/* receive data */
	printk(KERN_INFO "scatterlist for receive:\n");
	for (i = 0; i < nents; i++) {
		printk(KERN_INFO
		"sg[%d] -> "
		"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
			i, sg[i].page_link, sg[i].offset, sg[i].length);

		if (sg_is_last(&sg[i]))
			break;
	}

	/* put here your code to setup and exectute the dma operation */
	/* ... */

	/* example: zero bytes received */
	ret = 0;

	/* finish the dma operation and update the received data */
	kfifo_dma_in_finish(&fifo, ret);

	/* Prepare to transmit data, example: 8 bytes */
	nents = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
	printk(KERN_INFO "DMA sgl entries: %d\n", nents);
	if (!nents) {
		/* no data was available and no sgl was created */
		printk(KERN_WARNING "error kfifo_dma_out_prepare\n");
		return -EIO;
	}

	printk(KERN_INFO "scatterlist for transmit:\n");
	for (i = 0; i < nents; i++) {
		printk(KERN_INFO
		"sg[%d] -> "
		"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
			i, sg[i].page_link, sg[i].offset, sg[i].length);

		if (sg_is_last(&sg[i]))
			break;
	}

	/* put here your code to setup and exectute the dma operation */
	/* ... */

	/* example: 5 bytes transmitted */
	ret = 5;

	/* finish the dma operation and update the transmitted data */
	kfifo_dma_out_finish(&fifo, ret);

	ret = kfifo_len(&fifo);
	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));

	if (ret != 7) {
		printk(KERN_WARNING "size mismatch: test failed");
		return -EIO;
	}
	printk(KERN_INFO "test passed\n");

	return 0;
}
示例#2
0
static int __init example_init(void)
{
	int			i;
	unsigned int		ret;
	struct scatterlist	sg[10];

	printk(KERN_INFO "DMA fifo test start\n");

	if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
		printk(KERN_ERR "error kfifo_alloc\n");
		return 1;
	}

	printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));

	kfifo_in(&fifo, "test", 4);

	for (i = 0; i != 9; i++)
		kfifo_put(&fifo, &i);

	/* kick away first byte */
	ret = kfifo_get(&fifo, &i);

	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));

	ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
	printk(KERN_INFO "DMA sgl entries: %d\n", ret);

	/* if 0 was returned, fifo is full and no sgl was created */
	if (ret) {
		printk(KERN_INFO "scatterlist for receive:\n");
		for (i = 0; i < ARRAY_SIZE(sg); i++) {
			printk(KERN_INFO
			"sg[%d] -> "
			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
				i, sg[i].page_link, sg[i].offset, sg[i].length);

			if (sg_is_last(&sg[i]))
				break;
		}

		/* but here your code to setup and exectute the dma operation */
		/* ... */

		/* example: zero bytes received */
		ret = 0;

		/* finish the dma operation and update the received data */
		kfifo_dma_in_finish(&fifo, ret);
	}

	ret = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
	printk(KERN_INFO "DMA sgl entries: %d\n", ret);

	/* if 0 was returned, no data was available and no sgl was created */
	if (ret) {
		printk(KERN_INFO "scatterlist for transmit:\n");
		for (i = 0; i < ARRAY_SIZE(sg); i++) {
			printk(KERN_INFO
			"sg[%d] -> "
			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
				i, sg[i].page_link, sg[i].offset, sg[i].length);

			if (sg_is_last(&sg[i]))
				break;
		}

		/* but here your code to setup and exectute the dma operation */
		/* ... */

		/* example: 5 bytes transmitted */
		ret = 5;

		/* finish the dma operation and update the transmitted data */
		kfifo_dma_out_finish(&fifo, ret);
	}

	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));

	return 0;
}