[GitHub/mt8127/android_kernel_alcatel_ttab.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;
	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;
}

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;
399f1e30	27	unsigned int nents;
5bf2b193 SS	28	struct scatterlist sg[10];
	29
	30	printk(KERN_INFO "DMA fifo test start\n");
	31
	32	if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
a25effa4 AR	33	printk(KERN_WARNING "error kfifo_alloc\n");
a25effa4 AR	34	return -ENOMEM;
5bf2b193 SS	35	}
	36
	37	printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
	38
	39	kfifo_in(&fifo, "test", 4);
	40
	41	for (i = 0; i != 9; i++)
	42	kfifo_put(&fifo, &i);
	43
	44	/* kick away first byte */
a25effa4	45	kfifo_skip(&fifo);
5bf2b193 SS	46
	47	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
	48
a25effa4 AR	49	/*
	50	* Configure the kfifo buffer to receive data from DMA input.
	51	*
	52	* .--------------------------------------.
	53	* \| 0 \| 1 \| 2 \| ... \| 12 \| 13 \| ... \| 31 \|
	54	* \|---\|------------------\|---------------\|
	55	* \_/ \________________/ \_____________/
	56	* \ \ \
	57	* \ \_allocated data \
	58	* \_free space \_free space
	59	*
	60	* We need two different SG entries: one for the free space area at the
	61	* end of the kfifo buffer (19 bytes) and another for the first free
	62	* byte at the beginning, after the kfifo_skip().
	63	*/
7b34d525	64	sg_init_table(sg, ARRAY_SIZE(sg));
399f1e30 IS	65	nents = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
	66	printk(KERN_INFO "DMA sgl entries: %d\n", nents);
	67	if (!nents) {
a25effa4 AR	68	/* fifo is full and no sgl was created */
	69	printk(KERN_WARNING "error kfifo_dma_in_prepare\n");
	70	return -EIO;
	71	}
5bf2b193	72
a25effa4 AR	73	/* receive data */
a25effa4 AR	74	printk(KERN_INFO "scatterlist for receive:\n");
399f1e30	75	for (i = 0; i < nents; i++) {
a25effa4 AR	76	printk(KERN_INFO
	77	"sg[%d] -> "
	78	"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
	79	i, sg[i].page_link, sg[i].offset, sg[i].length);
5bf2b193	80
a25effa4 AR	81	if (sg_is_last(&sg[i]))
	82	break;
	83	}
5bf2b193	84
a25effa4 AR	85	/* put here your code to setup and exectute the dma operation */
a25effa4 AR	86	/* ... */
5bf2b193	87
a25effa4 AR	88	/* example: zero bytes received */
a25effa4 AR	89	ret = 0;
5bf2b193	90
a25effa4 AR	91	/* finish the dma operation and update the received data */
a25effa4 AR	92	kfifo_dma_in_finish(&fifo, ret);
5bf2b193	93
a25effa4	94	/* Prepare to transmit data, example: 8 bytes */
399f1e30 IS	95	nents = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
	96	printk(KERN_INFO "DMA sgl entries: %d\n", nents);
	97	if (!nents) {
a25effa4 AR	98	/* no data was available and no sgl was created */
	99	printk(KERN_WARNING "error kfifo_dma_out_prepare\n");
	100	return -EIO;
	101	}
5bf2b193	102
a25effa4	103	printk(KERN_INFO "scatterlist for transmit:\n");
399f1e30	104	for (i = 0; i < nents; i++) {
a25effa4 AR	105	printk(KERN_INFO
	106	"sg[%d] -> "
	107	"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
	108	i, sg[i].page_link, sg[i].offset, sg[i].length);
5bf2b193	109
a25effa4 AR	110	if (sg_is_last(&sg[i]))
	111	break;
	112	}
5bf2b193	113
a25effa4 AR	114	/* put here your code to setup and exectute the dma operation */
a25effa4 AR	115	/* ... */
5bf2b193	116
a25effa4 AR	117	/* example: 5 bytes transmitted */
a25effa4 AR	118	ret = 5;
5bf2b193	119
a25effa4 AR	120	/* finish the dma operation and update the transmitted data */
a25effa4 AR	121	kfifo_dma_out_finish(&fifo, ret);
5bf2b193	122
a25effa4	123	ret = kfifo_len(&fifo);
5bf2b193 SS	124	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
5bf2b193 SS	125
a25effa4 AR	126	if (ret != 7) {
	127	printk(KERN_WARNING "size mismatch: test failed");
	128	return -EIO;
	129	}
	130	printk(KERN_INFO "test passed\n");
	131
5bf2b193 SS	132	return 0;
	133	}
	134
	135	static void __exit example_exit(void)
	136	{
d83a71c4	137	kfifo_free(&fifo);
5bf2b193 SS	138	}
	139
	140	module_init(example_init);
	141	module_exit(example_exit);
	142	MODULE_LICENSE("GPL");
	143	MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");