From 5bf2b19320ec31d094d7370fdf536f7fd91fd799 Mon Sep 17 00:00:00 2001 From: Stefani Seibold Date: Tue, 10 Aug 2010 18:03:39 -0700 Subject: kfifo: add example files to the kernel sample directory Add four examples to the kernel sample directory. It shows how to handle: - a byte stream fifo - a integer type fifo - a dynamic record sized fifo - the fifo DMA functions [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Stefani Seibold Cc: Greg KH Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- samples/kfifo/dma-example.c | 115 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 115 insertions(+) create mode 100644 samples/kfifo/dma-example.c (limited to 'samples/kfifo/dma-example.c') diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c new file mode 100644 index 00000000000..b9482c28b41 --- /dev/null +++ b/samples/kfifo/dma-example.c @@ -0,0 +1,115 @@ +/* + * Sample fifo dma implementation + * + * Copyright (C) 2010 Stefani Seibold + * + * Released under the GPL version 2 only. + * + */ + +#include +#include +#include + +/* + * 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_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; +} + +static void __exit example_exit(void) +{ +#ifdef DYNAMIC + kfifo_free(&test); +#endif +} + +module_init(example_init); +module_exit(example_exit); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Stefani Seibold "); -- cgit v1.2.3