kfifo: add example files to the kernel sample directory

[linux-flexiantxendom0-natty.git] / samples / kfifo / dma-example.c

diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
new file mode 100644 (file)
index 0000000..b9482c2
--- /dev/null
+++ b/samples/kfifo/dma-example.c
@@ -0,0 +1,115 @@
+/*
+ * 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_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 <stefani@seibold.net>");