aboutsummaryrefslogtreecommitdiff
path: root/samples/kfifo/dma-example.c
diff options
context:
space:
mode:
authorAndrea Righi <arighi@develer.com>2010-08-19 14:13:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-20 09:34:54 -0700
commita25effa4d265eb5028c7d4a92a0ddd9267c3c43d (patch)
tree207c392483a80d7b21fdb92289c5c1b3e49c961a /samples/kfifo/dma-example.c
parentd83a71c4219191a9a881318ae5ca9b39aa1d0540 (diff)
downloadlinux-linaro-stable-a25effa4d265eb5028c7d4a92a0ddd9267c3c43d.tar.gz
kfifo: add explicit error checking in all the examples
Provide a check in all the kfifo examples to validate the correct execution of each testcase. Signed-off-by: Andrea Righi <arighi@develer.com> Acked-by: Stefani Seibold <stefani@seibold.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'samples/kfifo/dma-example.c')
-rw-r--r--samples/kfifo/dma-example.c106
1 files changed, 67 insertions, 39 deletions
diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
index 3682278785f7..ee03a4f0b64f 100644
--- a/samples/kfifo/dma-example.c
+++ b/samples/kfifo/dma-example.c
@@ -29,8 +29,8 @@ static int __init example_init(void)
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_WARNING "error kfifo_alloc\n");
+ return -ENOMEM;
}
printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
@@ -41,65 +41,93 @@ static int __init example_init(void)
kfifo_put(&fifo, &i);
/* kick away first byte */
- ret = kfifo_get(&fifo, &i);
+ 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;
+ }
- /* 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);
+ /* 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;
- }
+ if (sg_is_last(&sg[i]))
+ break;
+ }
- /* but here your code to setup and exectute the dma operation */
- /* ... */
+ /* put here your code to setup and exectute the dma operation */
+ /* ... */
- /* example: zero bytes received */
- ret = 0;
+ /* example: zero bytes received */
+ ret = 0;
- /* finish the dma operation and update the received data */
- kfifo_dma_in_finish(&fifo, ret);
- }
+ /* 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;
+ }
- /* 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);
+ 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;
- }
+ if (sg_is_last(&sg[i]))
+ break;
+ }
- /* but here your code to setup and exectute the dma operation */
- /* ... */
+ /* put here your code to setup and exectute the dma operation */
+ /* ... */
- /* example: 5 bytes transmitted */
- ret = 5;
+ /* example: 5 bytes transmitted */
+ ret = 5;
- /* finish the dma operation and update the transmitted data */
- kfifo_dma_out_finish(&fifo, ret);
- }
+ /* 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;
}