1 /* 2 * Generic bounce buffer implementation 3 * 4 * Copyright (C) 2012 Marek Vasut <marex@denx.de> 5 * 6 * See file CREDITS for list of people who contributed to this 7 * project. 8 * 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License as 11 * published by the Free Software Foundation; either version 2 of 12 * the License, or (at your option) any later version. 13 * 14 * This program is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 * GNU General Public License for more details. 18 * 19 * You should have received a copy of the GNU General Public License 20 * along with this program; if not, write to the Free Software 21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, 22 * MA 02111-1307 USA 23 */ 24 25 #include <common.h> 26 #include <malloc.h> 27 #include <errno.h> 28 #include <bouncebuf.h> 29 30 static int addr_aligned(struct bounce_buffer *state) 31 { 32 const ulong align_mask = ARCH_DMA_MINALIGN - 1; 33 34 /* Check if start is aligned */ 35 if ((ulong)state->user_buffer & align_mask) { 36 debug("Unaligned buffer address %p\n", state->user_buffer); 37 return 0; 38 } 39 40 /* Check if length is aligned */ 41 if (state->len != state->len_aligned) { 42 debug("Unaligned buffer length %d\n", state->len); 43 return 0; 44 } 45 46 /* Aligned */ 47 return 1; 48 } 49 50 int bounce_buffer_start(struct bounce_buffer *state, void *data, 51 size_t len, unsigned int flags) 52 { 53 state->user_buffer = data; 54 state->bounce_buffer = data; 55 state->len = len; 56 state->len_aligned = roundup(len, ARCH_DMA_MINALIGN); 57 state->flags = flags; 58 59 if (!addr_aligned(state)) { 60 state->bounce_buffer = memalign(ARCH_DMA_MINALIGN, 61 state->len_aligned); 62 if (!state->bounce_buffer) 63 return -ENOMEM; 64 65 if (state->flags & GEN_BB_READ) 66 memcpy(state->bounce_buffer, state->user_buffer, 67 state->len); 68 } 69 70 /* 71 * Flush data to RAM so DMA reads can pick it up, 72 * and any CPU writebacks don't race with DMA writes 73 */ 74 flush_dcache_range((unsigned long)state->bounce_buffer, 75 (unsigned long)(state->bounce_buffer) + 76 state->len_aligned); 77 78 return 0; 79 } 80 81 int bounce_buffer_stop(struct bounce_buffer *state) 82 { 83 if (state->flags & GEN_BB_WRITE) { 84 /* Invalidate cache so that CPU can see any newly DMA'd data */ 85 invalidate_dcache_range((unsigned long)state->bounce_buffer, 86 (unsigned long)(state->bounce_buffer) + 87 state->len_aligned); 88 } 89 90 if (state->bounce_buffer == state->user_buffer) 91 return 0; 92 93 if (state->flags & GEN_BB_WRITE) 94 memcpy(state->user_buffer, state->bounce_buffer, state->len); 95 96 free(state->bounce_buffer); 97 98 return 0; 99 } 100