Re: [PATCH v3 1/4] isa: Allow ISA-style drivers on modern systems

[Guenter Roeck]

On Mon, May 23, 2016 at 07:13:31PM -0400, William Breathitt Gray wrote:
> 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@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
> ---
>  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..a5338a6 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 EXPERT
> +	default n

I don't think an explicit "default n" is necessary.

> +	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
> 
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