On Thu, 21 Jul 2022 16:06:52 PDT (-0700), Rob Herring wrote:
On Tue, Jul 19, 2022 at 9:59 AM Palmer Dabbelt <palmer@xxxxxxxxxxx> wrote:
On Sun, 17 Jul 2022 17:41:14 PDT (-0700), shorne@xxxxxxxxx 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.
>
> 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?
> - pci_get_legacy_ide_irq, This function is only used on architectures
> that support PNP. It is only maintained for arm64, in other
> architectures it is removed.
>
> Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
> Link: https://lore.kernel.org/lkml/CAK8P3a0JmPeczfmMBE__vn=Jbvf=nkbpVaZCycyv40pZNCJJXQ@xxxxxxxxxxxxxx/
> Signed-off-by: Stafford Horne <shorne@xxxxxxxxx>
> ---
> Second note on isa_dma_bridge_buggy, this is set on x86 but it it also set in
> pci/quirks.c. We discussed limiting it only to x86 though as its a general
> quick triggered by pci ids I think it will be more tricky than we thought so I
> will leave as is. It might be nice to move it out of asm/dma.h and into
> asm/pci.h though.
>
> Since v2:
> - Nothing
> Since v1:
> - Remove definition of pci_get_legacy_ide_irq
>
> arch/arm64/include/asm/pci.h | 12 +++---------
> 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 | 36 ++++++++++++++++++++++++++++++++++++
> 5 files changed, 48 insertions(+), 73 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..1180e83712f5 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
> @@ -18,9 +17,6 @@
> (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)
> @@ -28,11 +24,9 @@ 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
My for-next changes these in bb356ddb78b2 ("RISC-V: PCI: Avoid handing
out address 0 to devices"). Do you mind either splitting out the
arch/riscv bits or having this in via some sort of shared tag?
Shouldn't the values not matter here if the IO and mem resources are
described in the DT (and don't use 0)? The values of 4 and 16 look
odd.
The linked thread has a fairly long discussion
<https://lore.kernel.org/all/alpine.DEB.2.21.2202260044180.25061@xxxxxxxxxxxxxxxxx/>.
I agree it's odd to have this in arch code: "don't hand out address 0"
isn't really a RISC-V constraint (ie, we don't have architecture-defined
limitations on these address spaces) but a constraint that comes from
the generic port I/O functions and some other related PCI/resource code
where the value 0 is a sentinel.
Maybe the right thing to do here is actually to make the default
definitions of these macros non-zero, or to add some sort of ARCH_
flavor of them and move that non-zero requirement closer to where it
comes from? From the look of it any port that uses the generic port I/O
functions and has 0 for these will be broken in the same way.
That said, I'm not really a PCI guy so maybe Bjorn or Maciej has a
better idea?
