[net-next-2.6.git] / samples / kfifo / dma-example.c

/*
 * Sample fifo dma implementation
 *
 * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
 *
 * Released under the GPL version 2 only.
 *
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kfifo.h>

/*
 * This module shows how to handle fifo dma operations.
 */

/* fifo size in elements (bytes) */
#define FIFO_SIZE	32

static struct kfifo fifo;

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_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));
	ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
	if (!ret) {
		/* 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 < 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;
	}

	/* 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 */
	ret = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
	if (!ret) {
		/* 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 < 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;
	}

	/* 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;
}

static void __exit example_exit(void)
{
	kfifo_free(&fifo);
}

module_init(example_init);
module_exit(example_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
Commit	Line	Data
5bf2b193 SS	1	/*
	2	* Sample fifo dma implementation
	3	*
	4	* Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
	5	*
	6	* Released under the GPL version 2 only.
	7	*
	8	*/
	9
	10	#include <linux/init.h>
	11	#include <linux/module.h>
	12	#include <linux/kfifo.h>
	13
	14	/*
	15	* This module shows how to handle fifo dma operations.
	16	*/
	17
	18	/* fifo size in elements (bytes) */
	19	#define FIFO_SIZE 32
	20
	21	static struct kfifo fifo;
	22
	23	static int __init example_init(void)
	24	{
	25	int i;
	26	unsigned int ret;
	27	struct scatterlist sg[10];
	28
	29	printk(KERN_INFO "DMA fifo test start\n");
	30
	31	if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
a25effa4 AR	32	printk(KERN_WARNING "error kfifo_alloc\n");
a25effa4 AR	33	return -ENOMEM;
5bf2b193 SS	34	}
	35
	36	printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
	37
	38	kfifo_in(&fifo, "test", 4);
	39
	40	for (i = 0; i != 9; i++)
	41	kfifo_put(&fifo, &i);
	42
	43	/* kick away first byte */
a25effa4	44	kfifo_skip(&fifo);
5bf2b193 SS	45
	46	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
	47
a25effa4 AR	48	/*
	49	* Configure the kfifo buffer to receive data from DMA input.
	50	*
	51	* .--------------------------------------.
	52	* \| 0 \| 1 \| 2 \| ... \| 12 \| 13 \| ... \| 31 \|
	53	* \|---\|------------------\|---------------\|
	54	* \_/ \________________/ \_____________/
	55	* \ \ \
	56	* \ \_allocated data \
	57	* \_free space \_free space
	58	*
	59	* We need two different SG entries: one for the free space area at the
	60	* end of the kfifo buffer (19 bytes) and another for the first free
	61	* byte at the beginning, after the kfifo_skip().
	62	*/
7b34d525	63	sg_init_table(sg, ARRAY_SIZE(sg));
5bf2b193 SS	64	ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
5bf2b193 SS	65	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
a25effa4 AR	66	if (!ret) {
	67	/* fifo is full and no sgl was created */
	68	printk(KERN_WARNING "error kfifo_dma_in_prepare\n");
	69	return -EIO;
	70	}
5bf2b193	71
a25effa4 AR	72	/* receive data */
	73	printk(KERN_INFO "scatterlist for receive:\n");
	74	for (i = 0; i < ARRAY_SIZE(sg); i++) {
	75	printk(KERN_INFO
	76	"sg[%d] -> "
	77	"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
	78	i, sg[i].page_link, sg[i].offset, sg[i].length);
5bf2b193	79
a25effa4 AR	80	if (sg_is_last(&sg[i]))
	81	break;
	82	}
5bf2b193	83
a25effa4 AR	84	/* put here your code to setup and exectute the dma operation */
a25effa4 AR	85	/* ... */
5bf2b193	86
a25effa4 AR	87	/* example: zero bytes received */
a25effa4 AR	88	ret = 0;
5bf2b193	89
a25effa4 AR	90	/* finish the dma operation and update the received data */
a25effa4 AR	91	kfifo_dma_in_finish(&fifo, ret);
5bf2b193	92
a25effa4	93	/* Prepare to transmit data, example: 8 bytes */
5bf2b193 SS	94	ret = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
5bf2b193 SS	95	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
a25effa4 AR	96	if (!ret) {
	97	/* no data was available and no sgl was created */
	98	printk(KERN_WARNING "error kfifo_dma_out_prepare\n");
	99	return -EIO;
	100	}
5bf2b193	101
a25effa4 AR	102	printk(KERN_INFO "scatterlist for transmit:\n");
	103	for (i = 0; i < ARRAY_SIZE(sg); i++) {
	104	printk(KERN_INFO
	105	"sg[%d] -> "
	106	"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
	107	i, sg[i].page_link, sg[i].offset, sg[i].length);
5bf2b193	108
a25effa4 AR	109	if (sg_is_last(&sg[i]))
	110	break;
	111	}
5bf2b193	112
a25effa4 AR	113	/* put here your code to setup and exectute the dma operation */
a25effa4 AR	114	/* ... */
5bf2b193	115
a25effa4 AR	116	/* example: 5 bytes transmitted */
a25effa4 AR	117	ret = 5;
5bf2b193	118
a25effa4 AR	119	/* finish the dma operation and update the transmitted data */
a25effa4 AR	120	kfifo_dma_out_finish(&fifo, ret);
5bf2b193	121
a25effa4	122	ret = kfifo_len(&fifo);
5bf2b193 SS	123	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
5bf2b193 SS	124
a25effa4 AR	125	if (ret != 7) {
	126	printk(KERN_WARNING "size mismatch: test failed");
	127	return -EIO;
	128	}
	129	printk(KERN_INFO "test passed\n");
	130
5bf2b193 SS	131	return 0;
	132	}
	133
	134	static void __exit example_exit(void)
	135	{
d83a71c4	136	kfifo_free(&fifo);
5bf2b193 SS	137	}
	138
	139	module_init(example_init);
	140	module_exit(example_exit);
	141	MODULE_LICENSE("GPL");
	142	MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");