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-rw-r--r--samples/kfifo/dma-example.c115
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diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
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+/*
+ * 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>");