[patch 1/4] pnp: only assign IORESOURCE_DMA if CONFIG_ISA_DMA_API is enabled

[patch 1/4] pnp: only assign IORESOURCE_DMA if CONFIG_ISA_DMA_API is enabled

[David Rientjes]

IORESOURCE_DMA cannot be assigned without utilizing the interface
provided by CONFIG_ISA_DMA_API, specifically request_dma() and
free_dma().  Thus, there's a strict dependency on the config option and
limits IORESOURCE_DMA only to architectures that support ISA-style DMA.

ia64 is not one of those architectures, so pnp_check_dma() no longer
needs to be special-cased for that architecture.

pnp_assign_resources() will now return -EINVAL if IORESOURCE_DMA is
attempted on such a kernel.

Signed-off-by: David Rientjes <rientjes@google.com>
---
 drivers/pnp/base.h     |    2 ++
 drivers/pnp/manager.c  |    7 ++++++-
 drivers/pnp/resource.c |    7 ++-----
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/pnp/base.h b/drivers/pnp/base.h
--- a/drivers/pnp/base.h
+++ b/drivers/pnp/base.h
@@ -142,7 +142,9 @@ void __pnp_remove_device(struct pnp_dev *dev);
 int pnp_check_port(struct pnp_dev *dev, struct resource *res);
 int pnp_check_mem(struct pnp_dev *dev, struct resource *res);
 int pnp_check_irq(struct pnp_dev *dev, struct resource *res);
+#ifdef CONFIG_ISA_DMA_API
 int pnp_check_dma(struct pnp_dev *dev, struct resource *res);
+#endif
 
 char *pnp_resource_type_name(struct resource *res);
 void dbg_pnp_show_resources(struct pnp_dev *dev, char *desc);
diff --git a/drivers/pnp/manager.c b/drivers/pnp/manager.c
--- a/drivers/pnp/manager.c
+++ b/drivers/pnp/manager.c
@@ -171,6 +171,7 @@ __add:
 	return 0;
 }
 
+#ifdef CONFIG_ISA_DMA_API
 static int pnp_assign_dma(struct pnp_dev *dev, struct pnp_dma *rule, int idx)
 {
 	struct resource *res, local_res;
@@ -210,6 +211,7 @@ __add:
 	pnp_add_dma_resource(dev, res->start, res->flags);
 	return 0;
 }
+#endif /* CONFIG_ISA_DMA_API */
 
 void pnp_init_resources(struct pnp_dev *dev)
 {
@@ -234,7 +236,8 @@ static void pnp_clean_resource_table(struct pnp_dev *dev)
 static int pnp_assign_resources(struct pnp_dev *dev, int set)
 {
 	struct pnp_option *option;
-	int nport = 0, nmem = 0, nirq = 0, ndma = 0;
+	int nport = 0, nmem = 0, nirq = 0;
+	int ndma __maybe_unused = 0;
 	int ret = 0;
 
 	pnp_dbg(&dev->dev, "pnp_assign_resources, try dependent set %d\n", set);
@@ -256,9 +259,11 @@ static int pnp_assign_resources(struct pnp_dev *dev, int set)
 		case IORESOURCE_IRQ:
 			ret = pnp_assign_irq(dev, &option->u.irq, nirq++);
 			break;
+#ifdef CONFIG_ISA_DMA_API
 		case IORESOURCE_DMA:
 			ret = pnp_assign_dma(dev, &option->u.dma, ndma++);
 			break;
+#endif
 		default:
 			ret = -EINVAL;
 			break;
diff --git a/drivers/pnp/resource.c b/drivers/pnp/resource.c
--- a/drivers/pnp/resource.c
+++ b/drivers/pnp/resource.c
@@ -409,9 +409,9 @@ int pnp_check_irq(struct pnp_dev *dev, struct resource *res)
 	return 1;
 }
 
+#ifdef CONFIG_ISA_DMA_API
 int pnp_check_dma(struct pnp_dev *dev, struct resource *res)
 {
-#ifndef CONFIG_IA64
 	int i;
 	struct pnp_dev *tdev;
 	struct resource *tres;
@@ -466,11 +466,8 @@ int pnp_check_dma(struct pnp_dev *dev, struct resource *res)
 	}
 
 	return 1;
-#else
-	/* IA64 does not have legacy DMA */
-	return 0;
-#endif
 }
+#endif /* CONFIG_ISA_DMA_API */
 
 unsigned long pnp_resource_type(struct resource *res)
 {

[patch 2/4] x86: only compile 8237A if CONFIG_ISA_DMA_API is enabled

[David Rientjes]

8237A utilizes the interface provided by CONFIG_ISA_DMA_API, specifically
claim_dma_lock() and release_dma_lock().  Thus, there's a strict
dependency on the config option and the module should only be loaded if
the kernel supports ISA-style DMA.

Signed-off-by: David Rientjes <rientjes@google.com>
---
 arch/x86/kernel/Makefile |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -41,12 +41,13 @@ obj-$(CONFIG_X86_32)	+= sys_i386_32.o i386_ksyms_32.o
 obj-$(CONFIG_X86_64)	+= sys_x86_64.o x8664_ksyms_64.o
 obj-$(CONFIG_X86_64)	+= syscall_64.o vsyscall_64.o
 obj-y			+= bootflag.o e820.o
-obj-y			+= pci-dma.o quirks.o i8237.o topology.o kdebugfs.o
+obj-y			+= pci-dma.o quirks.o topology.o kdebugfs.o
 obj-y			+= alternative.o i8253.o pci-nommu.o hw_breakpoint.o
 obj-y			+= tsc.o io_delay.o rtc.o
 obj-y			+= pci-iommu_table.o
 obj-y			+= resource.o
 
+obj-$(CONFIG_ISA_DMA_API)	+= i8237.o
 obj-$(CONFIG_X86_TRAMPOLINE)	+= trampoline.o
 obj-y				+= process.o
 obj-y				+= i387.o xsave.o

[patch 3/4] x86: only compile floppy driver if CONFIG_ISA_DMA_API is enabled

[David Rientjes]

The generic floppy disk driver utilizies the interface provided by
CONFIG_ISA_DMA_API, specifically claim_dma_lock(), release_dma_lock(),
request_dma(), and free_dma().  Thus, there's a strict dependency on the
config option and the driver should only be loaded if the kernel supports
ISA-style DMA.

Signed-off-by: David Rientjes <rientjes@google.com>
---
 arch/x86/Kconfig |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -139,7 +139,7 @@ config GENERIC_GPIO
 	bool
 
 config ARCH_MAY_HAVE_PC_FDC
-	def_bool y
+	def_bool ISA_DMA_API
 
 config RWSEM_GENERIC_SPINLOCK
 	def_bool !X86_XADD

[patch 4/4] x86: allow CONFIG_ISA_DMA_API to be disabled

[David Rientjes]

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>
---
 arch/x86/Kconfig           |   10 +++++++---
 arch/x86/include/asm/dma.h |    6 +++++-
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -119,7 +119,7 @@ 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
@@ -2000,9 +2000,13 @@ 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
--- 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 */
 

Re: [patch 4/4] x86: allow CONFIG_ISA_DMA_API to be disabled

[Arnd Bergmann]

On Thursday 27 January 2011 04:14:54 David Rientjes wrote:
> 
> 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).

But the x86_64 machines can also run 32 bit kernel, and I would expect
that they don't need ISA DMA in that configuration either.

I think it would make sense to let the CONFIG_EXPERT user disable
DMA for 32 bit as well.

	Arnd

[patch v2 4/4] x86: allow CONFIG_ISA_DMA_API to be disabled

[David Rientjes]

On Thu, 27 Jan 2011, Arnd Bergmann wrote:

> But the x86_64 machines can also run 32 bit kernel, and I would expect
> that they don't need ISA DMA in that configuration either.
> 
> I think it would make sense to let the CONFIG_EXPERT user disable
> DMA for 32 bit as well.
> 

Hmm, ok, I originally thought that allowing it to be disabled for 32-bit 
would cause people to regret it later when using pnp, for instance, and 
finding they need to require ISA-style DMA support for their devices.  I 
agree, though, that allowing CONFIG_EXPERT to disable it even for 32-bit 
sounds appropriate since they ultimately know what devices they're 
limiting their kernel from using.  Thanks!


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.

64-bit systems may compile a 32-bit kernel, so allow disabling it for
i386 as well.

Disabling CONFIG_ISA_DMA_API is dependent 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>
---
 arch/x86/Kconfig           |   10 +++++++---
 arch/x86/include/asm/dma.h |    6 +++++-
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -119,7 +119,7 @@ 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
@@ -2000,9 +2000,13 @@ 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 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
--- 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 */
 

Re: [patch 1/4] pnp: only assign IORESOURCE_DMA if CONFIG_ISA_DMA_API is enabled

[David Rientjes]

On Wed, 26 Jan 2011, David Rientjes wrote:

> IORESOURCE_DMA cannot be assigned without utilizing the interface
> provided by CONFIG_ISA_DMA_API, specifically request_dma() and
> free_dma().  Thus, there's a strict dependency on the config option and
> limits IORESOURCE_DMA only to architectures that support ISA-style DMA.
> 
> ia64 is not one of those architectures, so pnp_check_dma() no longer
> needs to be special-cased for that architecture.
> 
> pnp_assign_resources() will now return -EINVAL if IORESOURCE_DMA is
> attempted on such a kernel.
> 
> Signed-off-by: David Rientjes <rientjes@google.com>

Are there any objections to merging this?