From b660df3c9031ba2efded2d083c34f2ea5ff978ff Mon Sep 17 00:00:00 2001 From: Marek Vasut Date: Sun, 26 Aug 2012 15:19:06 +0000 Subject: COMMON: Implement common bounce buffer Implement common bounce buffer to be used on a less capable hardware. That includes hardware that can not do DMA from any address or such. Signed-off-by: Marek Vasut Cc: Fabio Estevam Cc: Andy Fleming Signed-off-by: Andy Fleming --- common/bouncebuf.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) create mode 100644 common/bouncebuf.c (limited to 'common/bouncebuf.c') diff --git a/common/bouncebuf.c b/common/bouncebuf.c new file mode 100644 index 0000000..4f827f8 --- /dev/null +++ b/common/bouncebuf.c @@ -0,0 +1,92 @@ +/* + * Generic bounce buffer implementation + * + * Copyright (C) 2012 Marek Vasut + * + * See file CREDITS for list of people who contributed to this + * project. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of + * the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + */ + +#include +#include +#include +#include + +static int addr_aligned(void *data, size_t len) +{ + const ulong align_mask = ARCH_DMA_MINALIGN - 1; + + /* Check if start is aligned */ + if ((ulong)data & align_mask) { + debug("Unaligned start address %p\n", data); + return 0; + } + + data += len; + + /* Check if end is aligned */ + if ((ulong)data & align_mask) { + debug("Unaligned end address %p\n", data); + return 0; + } + + /* Aligned */ + return 1; +} + +int bounce_buffer_start(void **data, size_t len, void **backup, uint8_t flags) +{ + void *tmp; + size_t alen; + + if (addr_aligned(*data, len)) { + *backup = NULL; + return 0; + } + + alen = roundup(len, ARCH_DMA_MINALIGN); + tmp = memalign(ARCH_DMA_MINALIGN, alen); + + if (!tmp) + return -ENOMEM; + + if (flags & GEN_BB_READ) + memcpy(tmp, *data, len); + + *backup = *data; + *data = tmp; + + return 0; +} + +int bounce_buffer_stop(void **data, size_t len, void **backup, uint8_t flags) +{ + void *tmp = *data; + + /* The buffer was already aligned, since "backup" is NULL. */ + if (!*backup) + return 0; + + if (flags & GEN_BB_WRITE) + memcpy(*backup, *data, len); + + *data = *backup; + free(tmp); + + return 0; +} -- cgit v1.1