[PATCH v2 1/4] isa: Allow ISA-style drivers on modern systems

William Breathitt Gray
2016-05-23T21:20:13Z

Several modern devices, such as PC/104 cards, are expected to run on
modern systems via an ISA bus interface. Since ISA is a legacy interface
for most modern architectures, ISA support should remain disabled in
general. Support for ISA-style drivers should be enabled on a per driver
basis.

To allow ISA-style drivers on modern systems, this patch introduces the
ISA_BUS_API and ISA_BUS Kconfig options. The ISA bus driver will now
build conditionally on the ISA_BUS_API Kconfig option, which defaults to
the legacy ISA Kconfig option. The ISA_BUS Kconfig option allows the
ISA_BUS_API Kconfig option to be selected on architectures which do not
enable ISA (e.g. X86_64).

The ISA_BUS Kconfig option is currently only implemented for X86
architectures. Other architectures may have their own ISA_BUS Kconfig
options added as required.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
arch/Kconfig | 3 +++
arch/x86/Kconfig | 10 ++++++++++
drivers/base/Makefile | 2 +-
include/linux/isa.h | 2 +-
4 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index b16e74e..9d9942f 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -598,6 +598,9 @@ config HAVE_STACK_VALIDATION
Architecture supports the 'objtool check' host tool command, which
performs compile-time stack metadata validation.

+config ISA_BUS_API
+ def_bool ISA
+
#
# ABI hall of shame
#
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0a7b885..6601912 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2439,6 +2439,16 @@ config PCI_CNB20LE_QUIRK

source "drivers/pci/Kconfig"

+config ISA_BUS
+ bool "ISA-style bus support on modern systems" if (X86 && EXPERT)
+ default n
+ select ISA_BUS_API
+ help
+ Enables ISA-style drivers on modern systems. This is necessary to
+ support PC/104 devices on X86_64 platforms.
+
+ If unsure, say N.
+
# x86_64 have no ISA slots, but can have ISA-style DMA.
config ISA_DMA_API
bool "ISA-style DMA support" if (X86_64 && EXPERT)
diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index 6b2a84e..2609ba2 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -10,7 +10,7 @@ obj-$(CONFIG_DMA_CMA) += dma-contiguous.o
obj-y += power/
obj-$(CONFIG_HAS_DMA) += dma-mapping.o
obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o
-obj-$(CONFIG_ISA) += isa.o
+obj-$(CONFIG_ISA_BUS_API) += isa.o
obj-$(CONFIG_FW_LOADER) += firmware_class.o
obj-$(CONFIG_NUMA) += node.o
obj-$(CONFIG_MEMORY_HOTPLUG_SPARSE) += memory.o
diff --git a/include/linux/isa.h b/include/linux/isa.h
index 5ab8528..384ab9b 100644
--- a/include/linux/isa.h
+++ b/include/linux/isa.h
@@ -22,7 +22,7 @@ struct isa_driver {

#define to_isa_driver(x) container_of((x), struct isa_driver, driver)

-#ifdef CONFIG_ISA
+#ifdef CONFIG_ISA_BUS_API
int isa_register_driver(struct isa_driver *, unsigned int);
void isa_unregister_driver(struct isa_driver *);
#else
--
2.7.3