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authorDavid Rientjes <rientjes@google.com>2011-03-23 02:34:59 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2011-03-23 03:44:16 +0300
commit1c00f0161f5e5bf1a441ea834c923f4102456489 (patch)
tree8d8bebdfe155d5afd60b412e5985691276b38baf /arch
parent8df3bd9e18cdc3539edea550be34605a240e15d4 (diff)
downloadlinux-1c00f0161f5e5bf1a441ea834c923f4102456489.tar.xz
x86: allow CONFIG_ISA_DMA_API to be disabled
Not all 64-bit systems require ISA-style DMA, so allow it to be configurable. x86 utilizes the generic ISA DMA allocator from kernel/dma.c, so require it only when CONFIG_ISA_DMA_API is enabled. Disabling CONFIG_ISA_DMA_API is dependent on x86_64 since those machines do not have ISA slots and benefit the most from disabling the option (and on CONFIG_EXPERT as required by H. Peter Anvin). When disabled, this also avoids declaring claim_dma_lock(), release_dma_lock(), request_dma(), and free_dma() since those interfaces will no longer be provided. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Bjorn Helgaas <bjorn.helgaas@hp.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/Kconfig10
-rw-r--r--arch/x86/include/asm/dma.h6
2 files changed, 12 insertions, 4 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 720206f46d04..d57ddd7573cc 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -123,7 +123,7 @@ config NEED_SG_DMA_LENGTH
def_bool y
config GENERIC_ISA_DMA
- def_bool y
+ def_bool ISA_DMA_API
config GENERIC_IOMAP
def_bool y
@@ -2002,9 +2002,13 @@ source "drivers/pci/pcie/Kconfig"
source "drivers/pci/Kconfig"
-# x86_64 have no ISA slots, but do have ISA-style DMA.
+# x86_64 have no ISA slots, but can have ISA-style DMA.
config ISA_DMA_API
- def_bool y
+ bool "ISA-style DMA support" if (X86_64 && EXPERT)
+ default y
+ help
+ Enables ISA-style DMA support for devices requiring such controllers.
+ If unsure, say Y.
if X86_32
diff --git a/arch/x86/include/asm/dma.h b/arch/x86/include/asm/dma.h
index ca1098a7e580..97b6d8114a43 100644
--- a/arch/x86/include/asm/dma.h
+++ b/arch/x86/include/asm/dma.h
@@ -151,6 +151,7 @@
#define DMA_AUTOINIT 0x10
+#ifdef CONFIG_ISA_DMA_API
extern spinlock_t dma_spin_lock;
static inline unsigned long claim_dma_lock(void)
@@ -164,6 +165,7 @@ static inline void release_dma_lock(unsigned long flags)
{
spin_unlock_irqrestore(&dma_spin_lock, flags);
}
+#endif /* CONFIG_ISA_DMA_API */
/* enable/disable a specific DMA channel */
static inline void enable_dma(unsigned int dmanr)
@@ -303,9 +305,11 @@ static inline int get_dma_residue(unsigned int dmanr)
}
-/* These are in kernel/dma.c: */
+/* These are in kernel/dma.c because x86 uses CONFIG_GENERIC_ISA_DMA */
+#ifdef CONFIG_ISA_DMA_API
extern int request_dma(unsigned int dmanr, const char *device_id);
extern void free_dma(unsigned int dmanr);
+#endif
/* From PCI */