/* * 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; 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 "); >diff options
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authorLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 10:56:56 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 10:56:56 -0800
commit2c5d9555d6d937966d79d4c6529a5f7b9206e405 (patch)
tree4f3d220ea3aeaadcae0796c5456e0ef9a908071d /net/caif/Kconfig
parent53cd1ad1a68fd10f677445e04ed63aa9ce39b36b (diff)
parent2ad5d52d42810bed95100a3d912679d8864421ec (diff)
Merge branch 'parisc-4.10-3' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux
Pull two parisc fixes from Helge Deller: "One fix to avoid usage of BITS_PER_LONG in user-space exported swab.h header which breaks compiling qemu, and one trivial fix for printk continuation in the parisc parport driver" * 'parisc-4.10-3' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux: parisc: Don't use BITS_PER_LONG in userspace-exported swab.h header parisc, parport_gsc: Fixes for printk continuation lines
Diffstat (limited to 'net/caif/Kconfig')