[RFC PATCH 2/2] asm-generic: Add new pci.h and use it

[RFC PATCH 2/2] asm-generic: Add new pci.h and use it

[Stafford Horne]

The asm/pci.h used for many newer architectures share similar
definitions.  Move the common parts to asm-generic/pci.h to allow for
sharing code.

Two things to note are:

 - isa_dma_bridge_buggy, traditionally this is defined in asm/dma.h but
   these architectures avoid creating that file and add the definition
   to asm/pci.h.
 - ARCH_GENERIC_PCI_MMAP_RESOURCE, csky does not define this so we
   undefine it after including asm-generic/pci.h.  Why doesn't csky
   define it?

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/lkml/CAK8P3a0JmPeczfmMBE__vn=Jbvf=nkbpVaZCycyv40pZNCJJXQ@mail.gmail.com/
Signed-off-by: Stafford Horne <shorne@gmail.com>
---
 arch/arm64/include/asm/pci.h | 18 ++--------------
 arch/csky/include/asm/pci.h  | 24 ++++------------------
 arch/riscv/include/asm/pci.h | 25 +++-------------------
 arch/um/include/asm/pci.h    | 24 ++--------------------
 include/asm-generic/pci.h    | 40 ++++++++++++++++++++++++++++++++++++
 5 files changed, 51 insertions(+), 80 deletions(-)
 create mode 100644 include/asm-generic/pci.h

diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
index b33ca260e3c9..016eb6b46dc0 100644
--- a/arch/arm64/include/asm/pci.h
+++ b/arch/arm64/include/asm/pci.h
@@ -9,7 +9,6 @@
 #include <asm/io.h>
 
 #define PCIBIOS_MIN_IO		0x1000
-#define PCIBIOS_MIN_MEM		0
 
 /*
  * Set to 1 if the kernel should re-assign all PCI bus numbers
@@ -18,21 +17,8 @@
 	(pci_has_flag(PCI_REASSIGN_ALL_BUS))
 
 #define arch_can_pci_mmap_wc() 1
-#define ARCH_GENERIC_PCI_MMAP_RESOURCE	1
 
-extern int isa_dma_bridge_buggy;
-
-#ifdef CONFIG_PCI
-static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
-{
-	/* no legacy IRQ on arm64 */
-	return -ENODEV;
-}
-
-static inline int pci_proc_domain(struct pci_bus *bus)
-{
-	return 1;
-}
-#endif  /* CONFIG_PCI */
+/* Generic PCI */
+#include <asm-generic/pci.h>
 
 #endif  /* __ASM_PCI_H */
diff --git a/arch/csky/include/asm/pci.h b/arch/csky/include/asm/pci.h
index ebc765b1f78b..44866c1ad461 100644
--- a/arch/csky/include/asm/pci.h
+++ b/arch/csky/include/asm/pci.h
@@ -9,26 +9,10 @@
 
 #include <asm/io.h>
 
-#define PCIBIOS_MIN_IO		0
-#define PCIBIOS_MIN_MEM		0
+/* Generic PCI */
+#include <asm-generic/pci.h>
 
-/* C-SKY shim does not initialize PCI bus */
-#define pcibios_assign_all_busses() 1
-
-extern int isa_dma_bridge_buggy;
-
-#ifdef CONFIG_PCI
-static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
-{
-	/* no legacy IRQ on csky */
-	return -ENODEV;
-}
-
-static inline int pci_proc_domain(struct pci_bus *bus)
-{
-	/* always show the domain in /proc */
-	return 1;
-}
-#endif  /* CONFIG_PCI */
+/* csky doesn't use generic pci resource mapping */
+#undef ARCH_GENERIC_PCI_MMAP_RESOURCE
 
 #endif  /* __ASM_CSKY_PCI_H */
diff --git a/arch/riscv/include/asm/pci.h b/arch/riscv/include/asm/pci.h
index 7fd52a30e605..12ce8150cfb0 100644
--- a/arch/riscv/include/asm/pci.h
+++ b/arch/riscv/include/asm/pci.h
@@ -12,29 +12,7 @@
 
 #include <asm/io.h>
 
-#define PCIBIOS_MIN_IO		0
-#define PCIBIOS_MIN_MEM		0
-
-/* RISC-V shim does not initialize PCI bus */
-#define pcibios_assign_all_busses() 1
-
-#define ARCH_GENERIC_PCI_MMAP_RESOURCE 1
-
-extern int isa_dma_bridge_buggy;
-
 #ifdef CONFIG_PCI
-static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
-{
-	/* no legacy IRQ on risc-v */
-	return -ENODEV;
-}
-
-static inline int pci_proc_domain(struct pci_bus *bus)
-{
-	/* always show the domain in /proc */
-	return 1;
-}
-
 #ifdef	CONFIG_NUMA
 
 static inline int pcibus_to_node(struct pci_bus *bus)
@@ -50,4 +28,7 @@ static inline int pcibus_to_node(struct pci_bus *bus)
 
 #endif  /* CONFIG_PCI */
 
+/* Generic PCI */
+#include <asm-generic/pci.h>
+
 #endif  /* _ASM_RISCV_PCI_H */
diff --git a/arch/um/include/asm/pci.h b/arch/um/include/asm/pci.h
index da13fd5519ef..34fe4921b5fa 100644
--- a/arch/um/include/asm/pci.h
+++ b/arch/um/include/asm/pci.h
@@ -4,28 +4,8 @@
 #include <linux/types.h>
 #include <asm/io.h>
 
-#define PCIBIOS_MIN_IO		0
-#define PCIBIOS_MIN_MEM		0
-
-#define pcibios_assign_all_busses() 1
-
-extern int isa_dma_bridge_buggy;
-
-#ifdef CONFIG_PCI
-static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
-{
-	/* no legacy IRQs */
-	return -ENODEV;
-}
-#endif
-
-#ifdef CONFIG_PCI_DOMAINS
-static inline int pci_proc_domain(struct pci_bus *bus)
-{
-	/* always show the domain in /proc */
-	return 1;
-}
-#endif  /* CONFIG_PCI */
+/* Generic PCI */
+#include <asm-generic/pci.h>
 
 #ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
 /*
diff --git a/include/asm-generic/pci.h b/include/asm-generic/pci.h
new file mode 100644
index 000000000000..1aa4d7a08aca
--- /dev/null
+++ b/include/asm-generic/pci.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __ASM_GENERIC_PCI_H
+#define __ASM_GENERIC_PCI_H
+
+#include <linux/types.h>
+
+#ifndef PCIBIOS_MIN_IO
+#define PCIBIOS_MIN_IO		0
+#endif
+
+#define PCIBIOS_MIN_MEM		0
+
+#ifndef pcibios_assign_all_busses
+/* For bootloaders that do not initialize the PCI bus */
+#define pcibios_assign_all_busses() 1
+#endif
+
+extern int isa_dma_bridge_buggy;
+
+/* Enable generic resource mapping code in drivers/pci/ */
+#define ARCH_GENERIC_PCI_MMAP_RESOURCE
+
+#ifdef CONFIG_PCI
+
+static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
+{
+	/* no legacy ide irq support */
+	return -ENODEV;
+}
+
+static inline int pci_proc_domain(struct pci_bus *bus)
+{
+	/* always show the domain in /proc */
+	return 1;
+}
+
+#endif /* CONFIG_PCI */
+
+#endif /* __ASM_GENERIC_PCI_H */
-- 
2.36.1


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Re: [RFC PATCH 2/2] asm-generic: Add new pci.h and use it

[Arnd Bergmann]

On Thu, Jul 14, 2022 at 11:46 PM Stafford Horne <shorne@gmail.com> wrote:
>
> The asm/pci.h used for many newer architectures share similar
> definitions.  Move the common parts to asm-generic/pci.h to allow for
> sharing code.

This looks very nice, thanks for doing it!

> Two things to note are:
>
>  - isa_dma_bridge_buggy, traditionally this is defined in asm/dma.h but
>    these architectures avoid creating that file and add the definition
>    to asm/pci.h.

I would prefer if we could just kill off this variable for non-x86, as it's
only set to a nonzero value in two implementations that are both
x86-specific and most of the references are gone. That does not have
to be part of this series though, if you don't want to address it here, just
add a comment to the new pci.h file.

>  - ARCH_GENERIC_PCI_MMAP_RESOURCE, csky does not define this so we
>    undefine it after including asm-generic/pci.h.  Why doesn't csky
>    define it?

Adding David Woodhouse to Cc, as he introduced this interface. As I
understand it, this was meant as a replacement for the old
architecture specific pci_mmap_page_range interface, and is ideally
used everywhere.

It's probably something that slipped through the review of csky and
should have been there.

As an aside, it seems the pci_mmap_page_range() cleanup was
left almost complete, with sparc being the only one left after
David Miller found a problem with the generic code. Not sure if
this was ever resolved:
https://lore.kernel.org/lkml/1519887203.622.3.camel@infradead.org/t/#u

> +#ifndef PCIBIOS_MIN_IO
> +#define PCIBIOS_MIN_IO         0
> +#endif
> +
> +#define PCIBIOS_MIN_MEM                0

We should probably #ifdef both of these for consistency.

> +static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
> +{
> +       /* no legacy ide irq support */
> +       return -ENODEV;
> +}

And this can just go away now, according to what we found.

        Arnd

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Re: [RFC PATCH 2/2] asm-generic: Add new pci.h and use it

[Stafford Horne]

On Fri, Jul 15, 2022 at 10:09:21AM +0200, Arnd Bergmann wrote:
> On Thu, Jul 14, 2022 at 11:46 PM Stafford Horne <shorne@gmail.com> wrote:
> >
> > The asm/pci.h used for many newer architectures share similar
> > definitions.  Move the common parts to asm-generic/pci.h to allow for
> > sharing code.
> 
> This looks very nice, thanks for doing it!
> 
> > Two things to note are:
> >
> >  - isa_dma_bridge_buggy, traditionally this is defined in asm/dma.h but
> >    these architectures avoid creating that file and add the definition
> >    to asm/pci.h.
> 
> I would prefer if we could just kill off this variable for non-x86, as it's
> only set to a nonzero value in two implementations that are both
> x86-specific and most of the references are gone. That does not have
> to be part of this series though, if you don't want to address it here, just
> add a comment to the new pci.h file.

I will look at it, maybe in a v3.

> >  - ARCH_GENERIC_PCI_MMAP_RESOURCE, csky does not define this so we
> >    undefine it after including asm-generic/pci.h.  Why doesn't csky
> >    define it?
> 
> Adding David Woodhouse to Cc, as he introduced this interface. As I
> understand it, this was meant as a replacement for the old
> architecture specific pci_mmap_page_range interface, and is ideally
> used everywhere.
> 
> It's probably something that slipped through the review of csky and
> should have been there.
> 
> As an aside, it seems the pci_mmap_page_range() cleanup was
> left almost complete, with sparc being the only one left after
> David Miller found a problem with the generic code. Not sure if
> this was ever resolved:
> https://lore.kernel.org/lkml/1519887203.622.3.camel@infradead.org/t/#u

I see, I will leave it foe now.

> > +#ifndef PCIBIOS_MIN_IO
> > +#define PCIBIOS_MIN_IO         0
> > +#endif
> > +
> > +#define PCIBIOS_MIN_MEM                0
> 
> We should probably #ifdef both of these for consistency.

OK.

> > +static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
> > +{
> > +       /* no legacy ide irq support */
> > +       return -ENODEV;
> > +}
> 
> And this can just go away now, according to what we found.

Yeah, that will be nice.

-Stafford

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