[U-Boot] [PATCH 1/4] COMMON: Implement common bounce buffer

[Marek Vasut]

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 <marex at denx.de>
Cc: Fabio Estevam <festevam at gmail.com>
Cc: Andy Fleming <afleming at freescale.com>
---
 common/Makefile     |    1 +
 common/bouncebuf.c  |   92 +++++++++++++++++++++++++++++++++++++++++++++++++++
 include/bouncebuf.h |   87 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 180 insertions(+)
 create mode 100644 common/bouncebuf.c
 create mode 100644 include/bouncebuf.h

diff --git a/common/Makefile b/common/Makefile
index 483eb4d..63f3523 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -188,6 +188,7 @@ endif
 ifdef CONFIG_SPL_BUILD
 COBJS-$(CONFIG_SPL_YMODEM_SUPPORT) += xyzModem.o
 endif
+COBJS-$(CONFIG_BOUNCE_BUFFER) += bouncebuf.o
 COBJS-y += console.o
 COBJS-y += dlmalloc.o
 COBJS-y += image.o
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 <marex at denx.de>
+ *
+ * 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 <common.h>
+#include <malloc.h>
+#include <errno.h>
+#include <bouncebuf.h>
+
+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;
+}
diff --git a/include/bouncebuf.h b/include/bouncebuf.h
new file mode 100644
index 0000000..31021c5
--- /dev/null
+++ b/include/bouncebuf.h
@@ -0,0 +1,87 @@
+/*
+ * Generic bounce buffer implementation
+ *
+ * Copyright (C) 2012 Marek Vasut <marex at denx.de>
+ *
+ * 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
+ */
+
+#ifndef __INCLUDE_BOUNCEBUF_H__
+#define __INCLUDE_BOUNCEBUF_H__
+
+/*
+ * GEN_BB_READ -- Data are read from the buffer eg. by DMA hardware.
+ * The source buffer is copied into the bounce buffer (if unaligned, otherwise
+ * the source buffer is used directly) upon start() call, then the operation
+ * requiring the aligned transfer happens, then the bounce buffer is lost upon
+ * stop() call.
+ */
+#define GEN_BB_READ	(1 << 0)
+/*
+ * GEN_BB_WRITE -- Data are written into the buffer eg. by DMA hardware.
+ * The source buffer starts in an undefined state upon start() call, then the
+ * operation requiring the aligned transfer happens, then the bounce buffer is
+ * copied into the destination buffer (if unaligned, otherwise destination
+ * buffer is used directly) upon stop() call.
+ */
+#define GEN_BB_WRITE	(1 << 1)
+/*
+ * GEN_BB_RW -- Data are read and written into the buffer eg. by DMA hardware.
+ * The source buffer is copied into the bounce buffer (if unaligned, otherwise
+ * the source buffer is used directly) upon start() call, then the  operation
+ * requiring the aligned transfer happens, then the bounce buffer is  copied
+ * into the destination buffer (if unaligned, otherwise destination buffer is
+ * used directly) upon stop() call.
+ */
+#define GEN_BB_RW	(GEN_BB_READ | GEN_BB_WRITE)
+
+#ifdef CONFIG_BOUNCE_BUFFER
+/**
+ * bounce_buffer_start() -- Start the bounce buffer session
+ * data:	pointer to buffer to be aligned
+ * len:		length of the buffer
+ * backup:	pointer to backup buffer (the original value is stored here if
+ *              needed
+ * flags:	flags describing the transaction, see above.
+ */
+int bounce_buffer_start(void **data, size_t len, void **backup, uint8_t flags);
+/**
+ * bounce_buffer_stop() -- Finish the bounce buffer session
+ * data:	pointer to buffer that was aligned
+ * len:		length of the buffer
+ * backup:	pointer to backup buffer (the original value is stored here if
+ *              needed
+ * flags:	flags describing the transaction, see above.
+ */
+int bounce_buffer_stop(void **data, size_t len, void **backup, uint8_t flags);
+#else
+static inline int bounce_buffer_start(void **data, size_t len, void **backup,
+					uint8_t flags)
+{
+	return 0;
+}
+
+static inline int bounce_buffer_stop(void **data, size_t len, void **backup,
+					uint8_t flags)
+{
+	return 0;
+}
+#endif
+
+#endif
-- 
1.7.10.4