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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
commit76cb841cb886eef6b3bee341a2266c76578724ad (patch)
treef5892e5ba6cc11949952a6ce4ecbe6d516d6ce58 /arch/xtensa/include/asm/dma.h
parentInitial commit. (diff)
downloadlinux-76cb841cb886eef6b3bee341a2266c76578724ad.tar.xz
linux-76cb841cb886eef6b3bee341a2266c76578724ad.zip
Adding upstream version 4.19.249.upstream/4.19.249
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r--arch/xtensa/include/asm/dma.h62
1 files changed, 62 insertions, 0 deletions
diff --git a/arch/xtensa/include/asm/dma.h b/arch/xtensa/include/asm/dma.h
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+/*
+ * include/asm-xtensa/dma.h
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2003 - 2005 Tensilica Inc.
+ */
+
+#ifndef _XTENSA_DMA_H
+#define _XTENSA_DMA_H
+
+#include <asm/io.h> /* need byte IO */
+
+/*
+ * This is only to be defined if we have PC-like DMA.
+ * By default this is not true on an Xtensa processor,
+ * however on boards with a PCI bus, such functionality
+ * might be emulated externally.
+ *
+ * NOTE: there still exists driver code that assumes
+ * this is defined, eg. drivers/sound/soundcard.c (as of 2.4).
+ */
+#define MAX_DMA_CHANNELS 8
+
+/*
+ * The maximum virtual address to which DMA transfers
+ * can be performed on this platform.
+ *
+ * NOTE: This is board (platform) specific, not processor-specific!
+ *
+ * NOTE: This assumes DMA transfers can only be performed on
+ * the section of physical memory contiguously mapped in virtual
+ * space for the kernel. For the Xtensa architecture, this
+ * means the maximum possible size of this DMA area is
+ * the size of the statically mapped kernel segment
+ * (XCHAL_KSEG_{CACHED,BYPASS}_SIZE), ie. 128 MB.
+ *
+ * NOTE: When the entire KSEG area is DMA capable, we subtract
+ * one from the max address so that the virt_to_phys() macro
+ * works correctly on the address (otherwise the address
+ * enters another area, and virt_to_phys() may not return
+ * the value desired).
+ */
+
+#ifndef MAX_DMA_ADDRESS
+#define MAX_DMA_ADDRESS (PAGE_OFFSET + XCHAL_KIO_SIZE - 1)
+#endif
+
+/* Reserve and release a DMA channel */
+extern int request_dma(unsigned int dmanr, const char * device_id);
+extern void free_dma(unsigned int dmanr);
+
+#ifdef CONFIG_PCI
+extern int isa_dma_bridge_buggy;
+#else
+#define isa_dma_bridge_buggy (0)
+#endif
+
+
+#endif