Re: [PATCH v7 06/17] ARM64 / ACPI: Make PCI optional for ACPI on ARM64

[Catalin Marinas]

On Wed, Jan 14, 2015 at 03:04:54PM +0000, Hanjun Guo wrote:
> Since PCI is not required in ACPI spec and ARM can run without
> it, introduce some stub functions to make PCI optional for ACPI,
> and make ACPI core run without CONFIG_PCI on ARM64.
> 
> When PCI is enabled on ARM64, ACPI core will need some PCI functions
> to make it functional, so introduce some empty functions here and
> implement it later.
> 
> Since ACPI on X86 and IA64 depends on PCI and this patch only makes
> PCI optional for ARM64, it will not break anything on X86 and IA64.
> 
> Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>
> Tested-by: Yijing Wang <wangyijing@xxxxxxxxxx>
> Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>

Is this patch still required, now that we have PCI for arm64? I know the
ACPI spec doesn't require PCI but do we expect any arm64 servers aimed
at ACPI without PCIe?

Anyway, that's not the main point, see more below.

> diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
> index 872ba93..fded096 100644
> --- a/arch/arm64/include/asm/pci.h
> +++ b/arch/arm64/include/asm/pci.h
> @@ -24,6 +24,12 @@
>   */
>  #define PCI_DMA_BUS_IS_PHYS	(0)
>  
> +static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
> +{
> +	/* no legacy IRQ on arm64 */
> +	return -ENODEV;
> +}
> +
>  extern int isa_dma_bridge_buggy;
>  
>  #ifdef CONFIG_PCI
> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
> index ce5836c..42fb195 100644
> --- a/arch/arm64/kernel/pci.c
> +++ b/arch/arm64/kernel/pci.c
> @@ -10,6 +10,7 @@
>   *
>   */
>  
> +#include <linux/acpi.h>
>  #include <linux/init.h>
>  #include <linux/io.h>
>  #include <linux/kernel.h>
> @@ -68,3 +69,30 @@ void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent)
>  	bus->domain_nr = domain;
>  }
>  #endif
> +
> +/*
> + * raw_pci_read/write - Platform-specific PCI config space access.
> + *
> + * Default empty implementation.  Replace with an architecture-specific setup
> + * routine, if necessary.
> + */
> +int raw_pci_read(unsigned int domain, unsigned int bus,
> +		  unsigned int devfn, int reg, int len, u32 *val)
> +{
> +	return -EINVAL;
> +}
> +
> +int raw_pci_write(unsigned int domain, unsigned int bus,
> +		unsigned int devfn, int reg, int len, u32 val)
> +{
> +	return -EINVAL;
> +}
> +
> +#ifdef CONFIG_ACPI
> +/* Root bridge scanning */
> +struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
> +{
> +	/* TODO: Should be revisited when implementing PCI on ACPI */
> +	return NULL;
> +}
> +#endif

Do these functions have anything to do with the subject? You add them in
arch/arm64/kernel/pci.c which is compiled only when CONFIG_PCI while the
commit log implies that you add them to allow CONFIG_PCI to be off.

When PCI is enabled and the above functions are compiled in, do they
need to return any useful data or just -EINVAL. Are they ever called?

> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 39f3ec1..c346011 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -43,7 +43,7 @@ acpi-y				+= processor_core.o
>  acpi-$(CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC) += processor_pdc.o
>  acpi-y				+= ec.o
>  acpi-$(CONFIG_ACPI_DOCK)	+= dock.o
> -acpi-y				+= pci_root.o pci_link.o pci_irq.o
> +acpi-$(CONFIG_PCI)		+= pci_root.o pci_link.o pci_irq.o
>  acpi-y				+= acpi_lpss.o
>  acpi-y				+= acpi_platform.o
>  acpi-y				+= acpi_pnp.o
> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> index 163e82f..c5ff8ba 100644
> --- a/drivers/acpi/internal.h
> +++ b/drivers/acpi/internal.h
> @@ -26,8 +26,13 @@
>  acpi_status acpi_os_initialize1(void);
>  int init_acpi_device_notify(void);
>  int acpi_scan_init(void);
> +#ifdef CONFIG_PCI
>  void acpi_pci_root_init(void);
>  void acpi_pci_link_init(void);
> +#else
> +static inline void acpi_pci_root_init(void) {}
> +static inline void acpi_pci_link_init(void) {}
> +#endif
>  void acpi_processor_init(void);
>  void acpi_platform_init(void);
>  void acpi_pnp_init(void);

That's a good clean-up.

> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 360a966..1476a66 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -564,15 +564,6 @@ struct pci_ops {
>  	int (*write)(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 val);
>  };
>  
> -/*
> - * ACPI needs to be able to access PCI config space before we've done a
> - * PCI bus scan and created pci_bus structures.
> - */
> -int raw_pci_read(unsigned int domain, unsigned int bus, unsigned int devfn,
> -		 int reg, int len, u32 *val);
> -int raw_pci_write(unsigned int domain, unsigned int bus, unsigned int devfn,
> -		  int reg, int len, u32 val);
> -
>  struct pci_bus_region {
>  	dma_addr_t start;
>  	dma_addr_t end;
> @@ -1329,6 +1320,16 @@ typedef int (*arch_set_vga_state_t)(struct pci_dev *pdev, bool decode,
>  		      unsigned int command_bits, u32 flags);
>  void pci_register_set_vga_state(arch_set_vga_state_t func);
>  
> +/*
> + * ACPI needs to be able to access PCI config space before we've done a
> + * PCI bus scan and created pci_bus structures.
> + */
> +int raw_pci_read(unsigned int domain, unsigned int bus, unsigned int devfn,
> +		 int reg, int len, u32 *val);
> +int raw_pci_write(unsigned int domain, unsigned int bus, unsigned int devfn,
> +		  int reg, int len, u32 val);
> +void pcibios_penalize_isa_irq(int irq, int active);
> +
>  #else /* CONFIG_PCI is not enabled */
>  
>  /*
> @@ -1430,6 +1431,23 @@ static inline struct pci_dev *pci_get_bus_and_slot(unsigned int bus,
>  						unsigned int devfn)
>  { return NULL; }
>  
> +static inline struct pci_bus *pci_find_bus(int domain, int busnr)
> +{ return NULL; }
> +
> +static inline int pci_bus_write_config_byte(struct pci_bus *bus,
> +				unsigned int devfn, int where, u8 val)
> +{ return -ENOSYS; }
> +
> +static inline int raw_pci_read(unsigned int domain, unsigned int bus,
> +			unsigned int devfn, int reg, int len, u32 *val)
> +{ return -ENOSYS; }
> +
> +static inline int raw_pci_write(unsigned int domain, unsigned int bus,
> +			unsigned int devfn, int reg, int len, u32 val)
> +{ return -ENOSYS; }

So you implement the !CONFIG_PCI functions here to return -ENOSYS while
the arm64 CONFIG_PCI ones would return -EINVAL. I'm confused.

-- 
Catalin
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