[PATCH v3 01/38] Kconfig: introduce HAS_IOPORT option and select it as necessary

[PATCH v3 01/38] Kconfig: introduce HAS_IOPORT option and select it as necessary

[Niklas Schnelle]

We introduce a new HAS_IOPORT Kconfig option to indicate support for I/O
Port access. In a future patch HAS_IOPORT=n will disable compilation of
the I/O accessor functions inb()/outb() and friends on architectures
which can not meaningfully support legacy I/O spaces such as s390. Also
add dependencies on HAS_IOPORT for the ISA and HAVE_EISA config options
as these busses always go along with HAS_IOPORT.

The "depends on" relations on HAS_IOPORT in drivers as well as ifdefs
for HAS_IOPORT specific sections will be added in subsequent patches on
a per subsystem basis.

Co-developed-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
 arch/alpha/Kconfig      | 1 +
 arch/arm/Kconfig        | 1 +
 arch/arm64/Kconfig      | 1 +
 arch/ia64/Kconfig       | 1 +
 arch/m68k/Kconfig       | 1 +
 arch/microblaze/Kconfig | 1 +
 arch/mips/Kconfig       | 2 ++
 arch/parisc/Kconfig     | 2 ++
 arch/powerpc/Kconfig    | 2 +-
 arch/riscv/Kconfig      | 1 +
 arch/sh/Kconfig         | 1 +
 arch/sparc/Kconfig      | 1 +
 arch/um/Kconfig         | 1 +
 arch/x86/Kconfig        | 2 ++
 drivers/bus/Kconfig     | 2 +-
 drivers/eisa/Kconfig    | 1 +
 lib/Kconfig             | 4 ++++
 lib/Kconfig.kgdb        | 3 ++-
 18 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 780d4673c3ca..a5c2b1aa46b0 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -27,6 +27,7 @@ config ALPHA
 	select AUDIT_ARCH
 	select GENERIC_CPU_VULNERABILITIES
 	select GENERIC_SMP_IDLE_THREAD
+	select HAS_IOPORT
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_MOD_ARCH_SPECIFIC
 	select MODULES_USE_ELF_RELA
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index e24a9820e12f..4acb5bc4b52a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -70,6 +70,7 @@ config ARM
 	select GENERIC_SCHED_CLOCK
 	select GENERIC_SMP_IDLE_THREAD
 	select HARDIRQS_SW_RESEND
+	select HAS_IOPORT
 	select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT
 	select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
 	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 1023e896d46b..b740019c4aee 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -145,6 +145,7 @@ config ARM64
 	select GENERIC_GETTIMEOFDAY
 	select GENERIC_VDSO_TIME_NS
 	select HARDIRQS_SW_RESEND
+	select HAS_IOPORT
 	select HAVE_MOVE_PMD
 	select HAVE_MOVE_PUD
 	select HAVE_PCI
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index d7e4a24e8644..2e13ec8263b9 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -25,6 +25,7 @@ config IA64
 	select PCI_DOMAINS if PCI
 	select PCI_MSI
 	select PCI_SYSCALL if PCI
+	select HAS_IOPORT
 	select HAVE_ASM_MODVERSIONS
 	select HAVE_UNSTABLE_SCHED_CLOCK
 	select HAVE_EXIT_THREAD
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 82154952e574..40198a1ebe27 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -18,6 +18,7 @@ config M68K
 	select GENERIC_CPU_DEVICES
 	select GENERIC_IOMAP
 	select GENERIC_IRQ_SHOW
+	select HAS_IOPORT if PCI || ISA || ATARI_ROM_ISA
 	select HAVE_ARCH_SECCOMP
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ASM_MODVERSIONS
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index cc88af6fa7a4..211f338d6235 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -21,6 +21,7 @@ config MICROBLAZE
 	select GENERIC_IRQ_SHOW
 	select GENERIC_PCI_IOMAP
 	select GENERIC_SCHED_CLOCK
+	select HAS_IOPORT if PCI
 	select HAVE_ARCH_HASH
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_SECCOMP
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index e2f3ca73f40d..64760fcd7b52 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -47,6 +47,7 @@ config MIPS
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_TIME_VSYSCALL
 	select GUP_GET_PXX_LOW_HIGH if CPU_MIPS32 && PHYS_ADDR_T_64BIT
+	select HAS_IOPORT if !NO_IOPORT_MAP
 	select HAVE_ARCH_COMPILER_H
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_KGDB if MIPS_FP_SUPPORT
@@ -3120,6 +3121,7 @@ config PCI_DRIVERS_LEGACY
 # users to choose the right thing ...
 #
 config ISA
+	depends on HAS_IOPORT
 	bool
 
 config TC
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index a98940e64243..5eeacc72e4da 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -47,6 +47,7 @@ config PARISC
 	select MODULES_USE_ELF_RELA
 	select CLONE_BACKWARDS
 	select TTY # Needed for pdc_cons.c
+	select HAS_IOPORT if PCI
 	select HAVE_DEBUG_STACKOVERFLOW
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_HASH
@@ -131,6 +132,7 @@ config STACKTRACE_SUPPORT
 
 config ISA_DMA_API
 	bool
+	depends on HAS_IOPORT
 
 config ARCH_MAY_HAVE_PC_FDC
 	bool
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index a6c4407d3ec8..f7de646c074a 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -188,6 +188,7 @@ config PPC
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_TIME_VSYSCALL
 	select GENERIC_VDSO_TIME_NS
+	select HAS_IOPORT			if PCI
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_HUGE_VMALLOC		if HAVE_ARCH_HUGE_VMAP
 	select HAVE_ARCH_HUGE_VMAP		if PPC_RADIX_MMU || PPC_8xx
@@ -1070,7 +1071,6 @@ menu "Bus options"
 
 config ISA
 	bool "Support for ISA-bus hardware"
-	depends on PPC_CHRP
 	select PPC_I8259
 	help
 	  Find out whether you have ISA slots on your motherboard.  ISA is the
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index c5e42cc37604..b957d12a171b 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -74,6 +74,7 @@ config RISCV
 	select GENERIC_TIME_VSYSCALL if MMU && 64BIT
 	select GENERIC_VDSO_TIME_NS if HAVE_GENERIC_VDSO
 	select HARDIRQS_SW_RESEND
+	select HAS_IOPORT if MMU
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_HUGE_VMALLOC if HAVE_ARCH_HUGE_VMAP
 	select HAVE_ARCH_HUGE_VMAP if MMU && 64BIT && !XIP_KERNEL
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 0665ac0add0b..cfb797bc4200 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -25,6 +25,7 @@ config SUPERH
 	select GENERIC_SCHED_CLOCK
 	select GENERIC_SMP_IDLE_THREAD
 	select GUP_GET_PXX_LOW_HIGH if X2TLB
+	select HAS_IOPORT if HAS_IOPORT_MAP
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_SECCOMP_FILTER
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 84437a4c6545..d4c1d96f85cd 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -32,6 +32,7 @@ config SPARC
 	select GENERIC_IRQ_SHOW
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select GENERIC_PCI_IOMAP
+	select HAS_IOPORT
 	select HAVE_NMI_WATCHDOG if SPARC64
 	select HAVE_CBPF_JIT if SPARC32
 	select HAVE_EBPF_JIT if SPARC64
diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 541a9b18e343..452d268be2e8 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -56,6 +56,7 @@ config NO_IOPORT_MAP
 
 config ISA
 	bool
+	depends on HAS_IOPORT
 
 config SBUS
 	bool
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a825bf031f49..634dd42532f3 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -162,6 +162,7 @@ config X86
 	select GUP_GET_PXX_LOW_HIGH		if X86_PAE
 	select HARDIRQS_SW_RESEND
 	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
+	select HAS_IOPORT
 	select HAVE_ACPI_APEI			if ACPI
 	select HAVE_ACPI_APEI_NMI		if ACPI
 	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
@@ -2893,6 +2894,7 @@ if X86_32
 
 config ISA
 	bool "ISA support"
+	depends on HAS_IOPORT
 	help
 	  Find out whether you have ISA slots on your motherboard.  ISA is the
 	  name of a bus system, i.e. the way the CPU talks to the other stuff
diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 7bfe998f3514..fcfa280df98a 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -81,7 +81,7 @@ config MOXTET
 config HISILICON_LPC
 	bool "Support for ISA I/O space on HiSilicon Hip06/7"
 	depends on (ARM64 && ARCH_HISI) || (COMPILE_TEST && !ALPHA && !HEXAGON && !PARISC)
-	depends on HAS_IOMEM
+	depends on HAS_IOPORT
 	select INDIRECT_PIO if ARM64
 	help
 	  Driver to enable I/O access to devices attached to the Low Pin
diff --git a/drivers/eisa/Kconfig b/drivers/eisa/Kconfig
index c8bbf90209f5..d3f62de72259 100644
--- a/drivers/eisa/Kconfig
+++ b/drivers/eisa/Kconfig
@@ -5,6 +5,7 @@
 
 config HAVE_EISA
 	bool
+	depends on HAS_IOPORT
 
 menuconfig EISA
 	bool "EISA support"
diff --git a/lib/Kconfig b/lib/Kconfig
index ce2abffb9ed8..5c2da561c516 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -92,6 +92,7 @@ config ARCH_USE_SYM_ANNOTATIONS
 config INDIRECT_PIO
 	bool "Access I/O in non-MMIO mode"
 	depends on ARM64
+	depends on HAS_IOPORT
 	help
 	  On some platforms where no separate I/O space exists, there are I/O
 	  hosts which can not be accessed in MMIO mode. Using the logical PIO
@@ -509,6 +510,9 @@ config HAS_IOMEM
 	depends on !NO_IOMEM
 	default y
 
+config HAS_IOPORT
+	bool
+
 config HAS_IOPORT_MAP
 	bool
 	depends on HAS_IOMEM && !NO_IOPORT_MAP
diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb
index 3b9a44008433..c68e4d9dcecb 100644
--- a/lib/Kconfig.kgdb
+++ b/lib/Kconfig.kgdb
@@ -121,7 +121,8 @@ config KDB_DEFAULT_ENABLE
 
 config KDB_KEYBOARD
 	bool "KGDB_KDB: keyboard as input device"
-	depends on VT && KGDB_KDB && !PARISC
+	depends on HAS_IOPORT
+	depends on VT && KGDB_KDB
 	default n
 	help
 	  KDB can use a PS/2 type keyboard for an input device
-- 
2.37.2

Re: [PATCH v3 01/38] Kconfig: introduce HAS_IOPORT option and select it as necessary

[Johannes Berg]

On Tue, 2023-03-14 at 13:11 +0100, Niklas Schnelle wrote:
> --- a/arch/um/Kconfig
> +++ b/arch/um/Kconfig
> @@ -56,6 +56,7 @@ config NO_IOPORT_MAP
>  
>  config ISA
>  	bool
> +	depends on HAS_IOPORT
> 

config ISA here is already unselectable, and nothing ever does "select
ISA" (only in some other architectures), so is there much point in this?

I'm not even sure why this exists at all.

But anyway, adding a dependency to a always-false symbol doesn't make it
less always-false :-)

Acked-by: Johannes Berg <johannes@sipsolutions.net> # for ARCH=um


Certainly will be nice to get rid of this cruft for architectures that
don't have it.

johannes

Re: [PATCH v3 01/38] Kconfig: introduce HAS_IOPORT option and select it as necessary

[Niklas Schnelle]

On Tue, 2023-03-14 at 13:37 +0100, Johannes Berg wrote:
> On Tue, 2023-03-14 at 13:11 +0100, Niklas Schnelle wrote:
> > --- a/arch/um/Kconfig
> > +++ b/arch/um/Kconfig
> > @@ -56,6 +56,7 @@ config NO_IOPORT_MAP
> >  
> >  config ISA
> >  	bool
> > +	depends on HAS_IOPORT
> > 
> 
> config ISA here is already unselectable, and nothing ever does "select
> ISA" (only in some other architectures), so is there much point in this?
> 
> I'm not even sure why this exists at all.

You're right there's not much point and I dropped this for v4. I agree
that probably the whole "config ISA" could be removed if it's always
false anyway but that seems out of scope for this patch.

> 
> But anyway, adding a dependency to a always-false symbol doesn't make it
> less always-false :-)
> 
> Acked-by: Johannes Berg <johannes@sipsolutions.net> # for ARCH=um

Thanks

> 
> 
> Certainly will be nice to get rid of this cruft for architectures that
> don't have it.
> 
> johannes

Yes, also, for s390 the broken NULL + port number access in the generic
inb()/outb() currently causes the only remaining clang warning on
defconfig builds.

Re: [PATCH v3 01/38] Kconfig: introduce HAS_IOPORT option and select it as necessary

[Geert Uytterhoeven]

On Tue, Mar 14, 2023 at 1:13 PM Niklas Schnelle <schnelle@linux.ibm.com> wrote:
> We introduce a new HAS_IOPORT Kconfig option to indicate support for I/O
> Port access. In a future patch HAS_IOPORT=n will disable compilation of
> the I/O accessor functions inb()/outb() and friends on architectures
> which can not meaningfully support legacy I/O spaces such as s390. Also
> add dependencies on HAS_IOPORT for the ISA and HAVE_EISA config options
> as these busses always go along with HAS_IOPORT.
>
> The "depends on" relations on HAS_IOPORT in drivers as well as ifdefs
> for HAS_IOPORT specific sections will be added in subsequent patches on
> a per subsystem basis.
>
> Co-developed-by: Arnd Bergmann <arnd@kernel.org>
> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>

>  arch/m68k/Kconfig       | 1 +

Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v3 01/38] Kconfig: introduce HAS_IOPORT option and select it as necessary

[Arnd Bergmann]

On Tue, Mar 14, 2023, at 13:11, Niklas Schnelle wrote:
> We introduce a new HAS_IOPORT Kconfig option to indicate support for I/O
> Port access. In a future patch HAS_IOPORT=n will disable compilation of
> the I/O accessor functions inb()/outb() and friends on architectures
> which can not meaningfully support legacy I/O spaces such as s390. Also
> add dependencies on HAS_IOPORT for the ISA and HAVE_EISA config options
> as these busses always go along with HAS_IOPORT.
>
> The "depends on" relations on HAS_IOPORT in drivers as well as ifdefs
> for HAS_IOPORT specific sections will be added in subsequent patches on
> a per subsystem basis.

I think it would be helpful to enumerate which architectures
do not get HAS_IOPORT added, as they will be affected more.

> Co-developed-by: Arnd Bergmann <arnd@kernel.org>
> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>

If there are no objections, I could send this first patch for the
asm-generic tree as a preparation for 6.3, so we are able to merge
the other patches through subsystem maintainer tree for 6.4.

arch/loongarch/ will now also need to select HAS_IOPORT
uncontitionally, this architecture was added after you
sent v2.

> diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
> index a98940e64243..5eeacc72e4da 100644
> --- a/arch/parisc/Kconfig
> +++ b/arch/parisc/Kconfig
> @@ -47,6 +47,7 @@ config PARISC
>  	select MODULES_USE_ELF_RELA
>  	select CLONE_BACKWARDS
>  	select TTY # Needed for pdc_cons.c
> +	select HAS_IOPORT if PCI

It's also needed for EISA and I think you should select it
from CONFIG_GSC in drivers/parisc/Kconfig for this purpose.

This could also be 'select HAS_IOPORT if PCI || EISA', but
that would require removing the 'depends on HAS_IOPORT'
under drivers/eisa/.

>  	select HAVE_DEBUG_STACKOVERFLOW
>  	select HAVE_ARCH_AUDITSYSCALL
>  	select HAVE_ARCH_HASH
> @@ -131,6 +132,7 @@ config STACKTRACE_SUPPORT
> 
>  config ISA_DMA_API
>  	bool
> +	depends on HAS_IOPORT
> 

This line is not really needed since there is no way to
enable ISA_DMA_API.

> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index a6c4407d3ec8..f7de646c074a 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -188,6 +188,7 @@ config PPC
>  	select GENERIC_SMP_IDLE_THREAD
>  	select GENERIC_TIME_VSYSCALL
>  	select GENERIC_VDSO_TIME_NS
> +	select HAS_IOPORT			if PCI
>  	select HAVE_ARCH_AUDITSYSCALL
>  	select HAVE_ARCH_HUGE_VMALLOC		if HAVE_ARCH_HUGE_VMAP
>  	select HAVE_ARCH_HUGE_VMAP		if PPC_RADIX_MMU || PPC_8xx
> @@ -1070,7 +1071,6 @@ menu "Bus options"
> 
>  config ISA
>  	bool "Support for ISA-bus hardware"
> -	depends on PPC_CHRP
>  	select PPC_I8259
>  	help
>  	  Find out whether you have ISA slots on your motherboard.  ISA is the

This line looks wrong, I think we should keep that dependency.
Did you get a circular dependency if you leave it in?

> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index a825bf031f49..634dd42532f3 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -162,6 +162,7 @@ config X86
>  	select GUP_GET_PXX_LOW_HIGH		if X86_PAE
>  	select HARDIRQS_SW_RESEND
>  	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
> +	select HAS_IOPORT
>  	select HAVE_ACPI_APEI			if ACPI
>  	select HAVE_ACPI_APEI_NMI		if ACPI
>  	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
> @@ -2893,6 +2894,7 @@ if X86_32
> 
>  config ISA
>  	bool "ISA support"
> +	depends on HAS_IOPORT
>  	help

HAS_IOPORT is selected unconditionally already, so this doesn't
really do anything.

> diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb
> index 3b9a44008433..c68e4d9dcecb 100644
> --- a/lib/Kconfig.kgdb
> +++ b/lib/Kconfig.kgdb
> @@ -121,7 +121,8 @@ config KDB_DEFAULT_ENABLE
> 
>  config KDB_KEYBOARD
>  	bool "KGDB_KDB: keyboard as input device"
> -	depends on VT && KGDB_KDB && !PARISC
> +	depends on HAS_IOPORT
> +	depends on VT && KGDB_KDB
>  	default n

This loses the !PARISC dependency, which I don't think is
intentional. The added HAS_IOPORT dependency makes sense
here, but I think this should be in a different patch
and not in the preparation.

    Arnd

Re: [PATCH v3 01/38] Kconfig: introduce HAS_IOPORT option and select it as necessary

[Niklas Schnelle]

On Tue, 2023-03-14 at 14:29 +0100, Arnd Bergmann wrote:
> On Tue, Mar 14, 2023, at 13:11, Niklas Schnelle wrote:
> > We introduce a new HAS_IOPORT Kconfig option to indicate support for I/O
> > Port access. In a future patch HAS_IOPORT=n will disable compilation of
> > the I/O accessor functions inb()/outb() and friends on architectures
> > which can not meaningfully support legacy I/O spaces such as s390. Also
> > add dependencies on HAS_IOPORT for the ISA and HAVE_EISA config options
> > as these busses always go along with HAS_IOPORT.
> > 
> > The "depends on" relations on HAS_IOPORT in drivers as well as ifdefs
> > for HAS_IOPORT specific sections will be added in subsequent patches on
> > a per subsystem basis.
> 
> I think it would be helpful to enumerate which architectures
> do not get HAS_IOPORT added, as they will be affected more.
> 
> > Co-developed-by: Arnd Bergmann <arnd@kernel.org>
> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> 
> If there are no objections, I could send this first patch for the
> asm-generic tree as a preparation for 6.3, so we are able to merge
> the other patches through subsystem maintainer tree for 6.4.
> 
> arch/loongarch/ will now also need to select HAS_IOPORT
> uncontitionally, this architecture was added after you
> sent v2.

Ah right. Added "select HAS_IOPORT" for LoongArch.

> 
> > diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
> > index a98940e64243..5eeacc72e4da 100644
> > --- a/arch/parisc/Kconfig
> > +++ b/arch/parisc/Kconfig
> > @@ -47,6 +47,7 @@ config PARISC
> >  	select MODULES_USE_ELF_RELA
> >  	select CLONE_BACKWARDS
> >  	select TTY # Needed for pdc_cons.c
> > +	select HAS_IOPORT if PCI
> 
> It's also needed for EISA and I think you should select it
> from CONFIG_GSC in drivers/parisc/Kconfig for this purpose.
> 
> This could also be 'select HAS_IOPORT if PCI || EISA', but
> that would require removing the 'depends on HAS_IOPORT'
> under drivers/eisa/.

I did use "select HAS_IOPORT if PCI || ISA || ATARI_ROM_ISA" in m68k so
I think ideally we would handle both in the same way. I don't have a
strong preference but I think the "select HAS_IOPORT if ..." puts it
all in a single place which is nice. Also I think this would make it
more similar architectures with unconditional HAS_IOPORT that thus
don't need "depends on HAS_IOPORT" in their "config ISA" either. As
also pointed by your comment below for x86. So will try to go this
route.

> 
> >  	select HAVE_DEBUG_STACKOVERFLOW
> >  	select HAVE_ARCH_AUDITSYSCALL
> >  	select HAVE_ARCH_HASH
> > @@ -131,6 +132,7 @@ config STACKTRACE_SUPPORT
> > 
> >  config ISA_DMA_API
> >  	bool
> > +	depends on HAS_IOPORT
> > 
> 
> This line is not really needed since there is no way to
> enable ISA_DMA_API.

Removed

> 
> > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> > index a6c4407d3ec8..f7de646c074a 100644
> > --- a/arch/powerpc/Kconfig
> > +++ b/arch/powerpc/Kconfig
> > @@ -188,6 +188,7 @@ config PPC
> >  	select GENERIC_SMP_IDLE_THREAD
> >  	select GENERIC_TIME_VSYSCALL
> >  	select GENERIC_VDSO_TIME_NS
> > +	select HAS_IOPORT			if PCI
> >  	select HAVE_ARCH_AUDITSYSCALL
> >  	select HAVE_ARCH_HUGE_VMALLOC		if HAVE_ARCH_HUGE_VMAP
> >  	select HAVE_ARCH_HUGE_VMAP		if PPC_RADIX_MMU || PPC_8xx
> > @@ -1070,7 +1071,6 @@ menu "Bus options"
> > 
> >  config ISA
> >  	bool "Support for ISA-bus hardware"
> > -	depends on PPC_CHRP
> >  	select PPC_I8259
> >  	help
> >  	  Find out whether you have ISA slots on your motherboard.  ISA is the
> 
> This line looks wrong, I think we should keep that dependency.
> Did you get a circular dependency if you leave it in?

I don't recall why this was removed. I guess it happened when I was
experimenting with adding "depends on HAS_IOPORT" for the ISA config
options but that ultimately lead to circular dependencies, must have
messed up when removing this here.

> 
> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index a825bf031f49..634dd42532f3 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -162,6 +162,7 @@ config X86
> >  	select GUP_GET_PXX_LOW_HIGH		if X86_PAE
> >  	select HARDIRQS_SW_RESEND
> >  	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
> > +	select HAS_IOPORT
> >  	select HAVE_ACPI_APEI			if ACPI
> >  	select HAVE_ACPI_APEI_NMI		if ACPI
> >  	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
> > @@ -2893,6 +2894,7 @@ if X86_32
> > 
> >  config ISA
> >  	bool "ISA support"
> > +	depends on HAS_IOPORT
> >  	help
> 
> HAS_IOPORT is selected unconditionally already, so this doesn't
> really do anything.

Removed.

> 
> > diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb
> > index 3b9a44008433..c68e4d9dcecb 100644
> > --- a/lib/Kconfig.kgdb
> > +++ b/lib/Kconfig.kgdb
> > @@ -121,7 +121,8 @@ config KDB_DEFAULT_ENABLE
> > 
> >  config KDB_KEYBOARD
> >  	bool "KGDB_KDB: keyboard as input device"
> > -	depends on VT && KGDB_KDB && !PARISC
> > +	depends on HAS_IOPORT
> > +	depends on VT && KGDB_KDB
> >  	default n
> 
> This loses the !PARISC dependency, which I don't think is
> intentional. The added HAS_IOPORT dependency makes sense
> here, but I think this should be in a different patch
> and not in the preparation.
> 
>     Arnd

Agree will put into its own patch and re-add the !PARISC

Re: [PATCH v3 01/38] Kconfig: introduce HAS_IOPORT option and select it as necessary

[Niklas Schnelle]

On Tue, 2023-03-14 at 13:11 +0100, Niklas Schnelle wrote:
> We introduce a new HAS_IOPORT Kconfig option to indicate support for I/O
> Port access. In a future patch HAS_IOPORT=n will disable compilation of
> the I/O accessor functions inb()/outb() and friends on architectures
> which can not meaningfully support legacy I/O spaces such as s390. Also
> add dependencies on HAS_IOPORT for the ISA and HAVE_EISA config options
> as these busses always go along with HAS_IOPORT.
> 
> The "depends on" relations on HAS_IOPORT in drivers as well as ifdefs
> for HAS_IOPORT specific sections will be added in subsequent patches on
> a per subsystem basis.
> 
> Co-developed-by: Arnd Bergmann <arnd@kernel.org>
> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> ---
> 

@Arnd, I swear I asked you and then added Signed-off-bys for all these
Co-developed-bys as suggested by checkpatch. Sadly that must have been
during my failed attempt of converting to b4 prep / b4 send before
sending this last Friday and then it got lost. It almost worked and is
a very nice work flow except that b4 currently can only use a single
list of To/Cc fields and for this treewide series that would probably
hit mail server limits. Added it now.

Thanks,
Niklas

Re: [PATCH v3 28/38] rtc: add HAS_IOPORT dependencies

[Geert Uytterhoeven]

Hi Arnd,

On Mon, May 8, 2023 at 10:01 PM Arnd Bergmann <arnd@arndb.de> wrote:
> On Mon, May 8, 2023, at 17:36, Niklas Schnelle wrote:
> > On Tue, 2023-03-14 at 13:52 +0100, Alexandre Belloni wrote:
> >> On 14/03/2023 13:12:06+0100, Niklas Schnelle wrote:
> >> > In a future patch HAS_IOPORT=n will result in inb()/outb() and friends
> >> > not being declared. We thus need to add HAS_IOPORT as dependency for
> >> > those drivers using them.
> >> >
> >> > Co-developed-by: Arnd Bergmann <arnd@kernel.org>
> >> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> >> > ---
> >> >  drivers/rtc/Kconfig | 4 +++-
> >> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >> >
> >> > diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> >> > index 5a71579af0a1..20aa77bf0a9f 100644
> >> > --- a/drivers/rtc/Kconfig
> >> > +++ b/drivers/rtc/Kconfig
> >> > @@ -956,6 +956,7 @@ comment "Platform RTC drivers"
> >> >  config RTC_DRV_CMOS
> >> >    tristate "PC-style 'CMOS'"
> >> >    depends on X86 || ARM || PPC || MIPS || SPARC64
> >> > +  depends on HAS_IOPORT
> >>
> >> Did you check that this will not break platforms that doesn't have RTC_PORT defined?
> >> >
> >
> > From what I can tell the CMOS_READ() macro this driver relies on uses
> > some form of inb() style I/O port access in all its definitions. So my
> > understanding is that this device is always accessed via I/O ports even
> > if the variants differ slightly and would make no sense on a platform
> > without any way of accessing I/O ports which is what lack of HAS_IOPORT
> > means. From what I can see even without RTC_PORT being defined the
> > CMOS_READ is still used. Hope that answers your question?
>
> I think the m68k/atari and mips/dec variants don't necessarily
> qualify as PIO, those are really just pointer dereferences, and
> they don't use the actual inb/outb functions.
>
> On atari, it looks like HAS_IOPORT may be set if ATARI_ROM_ISA
> is, but on dec it's never enabled.

Atari does not use RTC_DRV_CMOS, but still relies on generic RTC
instead.

Last time (in 2013?) I tried converting to RTC_DRV_CMOS by registering
an "rtc_cmos" platform device, I couldn't get it to work.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v3 28/38] rtc: add HAS_IOPORT dependencies

[Arnd Bergmann]

On Tue, May 9, 2023, at 08:38, Geert Uytterhoeven wrote:
> On Mon, May 8, 2023 at 10:01 PM Arnd Bergmann <arnd@arndb.de> wrote:
>> On Mon, May 8, 2023, at 17:36, Niklas Schnelle wrote:
>>
>> I think the m68k/atari and mips/dec variants don't necessarily
>> qualify as PIO, those are really just pointer dereferences, and
>> they don't use the actual inb/outb functions.
>>
>> On atari, it looks like HAS_IOPORT may be set if ATARI_ROM_ISA
>> is, but on dec it's never enabled.
>
> Atari does not use RTC_DRV_CMOS, but still relies on generic RTC
> instead.

Ah right, I now remember working on that code, so we're good on
m68k then. I think it should work for everyone using

       depends on HAS_IOPORT || ARCH_DECSTATION

in that case, as that is the only exception.

> Last time (in 2013?) I tried converting to RTC_DRV_CMOS by registering
> an "rtc_cmos" platform device, I couldn't get it to work.

If you ever want to revisit this, I suspect the harder part here
is to detach arch/m68k/ from the RTC_DRV_GENERIC code first, pushing
the device registration into the individual machine specific time.c
code. It's probably not even worth trying to share the rtc-cmos
driver, but it might be useful to share the library code like
RTC_DRV_ALPHA does.

   Arnd

Re: [PATCH v3 28/38] rtc: add HAS_IOPORT dependencies

[Geert Uytterhoeven]

Hi Arnd,

On Tue, May 9, 2023 at 10:23 AM Arnd Bergmann <arnd@arndb.de> wrote:
> On Tue, May 9, 2023, at 08:38, Geert Uytterhoeven wrote:
> > On Mon, May 8, 2023 at 10:01 PM Arnd Bergmann <arnd@arndb.de> wrote:
> >> On Mon, May 8, 2023, at 17:36, Niklas Schnelle wrote:
> >>
> >> I think the m68k/atari and mips/dec variants don't necessarily
> >> qualify as PIO, those are really just pointer dereferences, and
> >> they don't use the actual inb/outb functions.
> >>
> >> On atari, it looks like HAS_IOPORT may be set if ATARI_ROM_ISA
> >> is, but on dec it's never enabled.
> >
> > Atari does not use RTC_DRV_CMOS, but still relies on generic RTC
> > instead.
>
> Ah right, I now remember working on that code, so we're good on
> m68k then. I think it should work for everyone using
>
>        depends on HAS_IOPORT || ARCH_DECSTATION
>
> in that case, as that is the only exception.
>
> > Last time (in 2013?) I tried converting to RTC_DRV_CMOS by registering
> > an "rtc_cmos" platform device, I couldn't get it to work.
>
> If you ever want to revisit this, I suspect the harder part here
> is to detach arch/m68k/ from the RTC_DRV_GENERIC code first, pushing
> the device registration into the individual machine specific time.c
> code. It's probably not even worth trying to share the rtc-cmos
> driver, but it might be useful to share the library code like
> RTC_DRV_ALPHA does.

Arch/m68k is not that entangled with RTC_DRV_GENERIC, as amiga_defconfig
does not enable it, but enables CONFIG_RTC_DRV_MSM6242 and
CONFIG_RTC_DRV_RP5C01 instead.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v3 28/38] rtc: add HAS_IOPORT dependencies

[Arnd Bergmann]

On Tue, May 9, 2023, at 10:51, Geert Uytterhoeven wrote:
> On Tue, May 9, 2023 at 10:23 AM Arnd Bergmann <arnd@arndb.de> wrote:
>> On Tue, May 9, 2023, at 08:38, Geert Uytterhoeven wrote:
>> If you ever want to revisit this, I suspect the harder part here
>> is to detach arch/m68k/ from the RTC_DRV_GENERIC code first, pushing
>> the device registration into the individual machine specific time.c
>> code. It's probably not even worth trying to share the rtc-cmos
>> driver, but it might be useful to share the library code like
>> RTC_DRV_ALPHA does.
>
> Arch/m68k is not that entangled with RTC_DRV_GENERIC, as amiga_defconfig
> does not enable it, but enables CONFIG_RTC_DRV_MSM6242 and
> CONFIG_RTC_DRV_RP5C01 instead.

Ah, I see now, I misremembered this part. The only bit that
is shared on m68k is the mach_hwclk() function that is used
for either read_persistent_clock64() or rtc_generic on platforms
that have one. So any platform could indeed be converted from
mach_hwclk() to a custom rtc driver without affecting the others.

    Arnd