^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) // SPDX-License-Identifier: GPL-2.0-only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) * Sample fifo dma implementation
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) #include <linux/init.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) #include <linux/module.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) #include <linux/kfifo.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) * This module shows how to handle fifo dma operations.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) /* fifo size in elements (bytes) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) #define FIFO_SIZE 32
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) static struct kfifo fifo;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) static int __init example_init(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) int i;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) unsigned int ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) unsigned int nents;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) struct scatterlist sg[10];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) printk(KERN_INFO "DMA fifo test start\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) printk(KERN_WARNING "error kfifo_alloc\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) return -ENOMEM;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) kfifo_in(&fifo, "test", 4);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) for (i = 0; i != 9; i++)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) kfifo_put(&fifo, i);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) /* kick away first byte */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) kfifo_skip(&fifo);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) * Configure the kfifo buffer to receive data from DMA input.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) * .--------------------------------------.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) * | 0 | 1 | 2 | ... | 12 | 13 | ... | 31 |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) * |---|------------------|---------------|
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) * \_/ \________________/ \_____________/
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) * \ \ \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) * \ \_allocated data \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) * \_*free space* \_*free space*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) * We need two different SG entries: one for the free space area at the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) * end of the kfifo buffer (19 bytes) and another for the first free
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) * byte at the beginning, after the kfifo_skip().
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) sg_init_table(sg, ARRAY_SIZE(sg));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) nents = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) printk(KERN_INFO "DMA sgl entries: %d\n", nents);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) if (!nents) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) /* fifo is full and no sgl was created */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) printk(KERN_WARNING "error kfifo_dma_in_prepare\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) return -EIO;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) /* receive data */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) printk(KERN_INFO "scatterlist for receive:\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) for (i = 0; i < nents; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) printk(KERN_INFO
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) "sg[%d] -> "
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) "page %p offset 0x%.8x length 0x%.8x\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) i, sg_page(&sg[i]), sg[i].offset, sg[i].length);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) if (sg_is_last(&sg[i]))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) /* put here your code to setup and exectute the dma operation */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) /* ... */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) /* example: zero bytes received */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) ret = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) /* finish the dma operation and update the received data */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) kfifo_dma_in_finish(&fifo, ret);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) /* Prepare to transmit data, example: 8 bytes */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) nents = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) printk(KERN_INFO "DMA sgl entries: %d\n", nents);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) if (!nents) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) /* no data was available and no sgl was created */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) printk(KERN_WARNING "error kfifo_dma_out_prepare\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) return -EIO;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) printk(KERN_INFO "scatterlist for transmit:\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) for (i = 0; i < nents; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) printk(KERN_INFO
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) "sg[%d] -> "
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) "page %p offset 0x%.8x length 0x%.8x\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) i, sg_page(&sg[i]), sg[i].offset, sg[i].length);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) if (sg_is_last(&sg[i]))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) break;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) /* put here your code to setup and exectute the dma operation */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) /* ... */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) /* example: 5 bytes transmitted */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) ret = 5;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) /* finish the dma operation and update the transmitted data */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) kfifo_dma_out_finish(&fifo, ret);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) ret = kfifo_len(&fifo);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) if (ret != 7) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) printk(KERN_WARNING "size mismatch: test failed");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) return -EIO;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) printk(KERN_INFO "test passed\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) static void __exit example_exit(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) kfifo_free(&fifo);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) module_init(example_init);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) module_exit(example_exit);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) MODULE_LICENSE("GPL");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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