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

From: [email-masked] (Hanjun Guo)
Date: Sun, 18 Jan 2015 14:25:53 +0800

On 2015?01?16? 17:49, Catalin Marinas wrote:
> 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 <[email-masked]>
>> Tested-by: Yijing Wang <[email-masked]>
>> Signed-off-by: Hanjun Guo <[email-masked]>
>
> 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?

I think so, how about make ACPI depends on PCI on ARM64 too?

>
> 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.

My bad, I can update the change log to make it explicit it is needed
when PCI is enabled.

>
> 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?

They will be called if PCI root bridge is defined in DSDT, should I
print some warning message before it is implemented?

>
>> 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.

If we make ACPI depends on PCI on ARM64, these two stub functions
are not needed anymore.

>
>> 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.

return -ENOSYS in the arm64 CONFIG_PCI ones next version :)

Thanks
Hanjun