Re: [RFC PATCH V2 1/2] ACPI/PCI: Match PCI config space accessors against platfrom specific ECAM quirks

[Christopher Covington]

Hi Dongdong,

On 06/13/2016 09:02 AM, Dongdong Liu wrote:
> diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c
> index d3c3e85..49612b3 100644
> --- a/drivers/acpi/pci_mcfg.c
> +++ b/drivers/acpi/pci_mcfg.c
> @@ -22,6 +22,10 @@
>  #include <linux/kernel.h>
>  #include <linux/pci.h>
>  #include <linux/pci-acpi.h>
> +#include <linux/pci-ecam.h>
> +
> +/* Root pointer to the mapped MCFG table */
> +static struct acpi_table_mcfg *mcfg_table;
>  
>  /* Structure to hold entries from the MCFG table */
>  struct mcfg_entry {
> @@ -35,6 +39,38 @@ struct mcfg_entry {
>  /* List to save mcfg entries */
>  static LIST_HEAD(pci_mcfg_list);
>  
> +extern struct pci_cfg_fixup __start_acpi_mcfg_fixups[];
> +extern struct pci_cfg_fixup __end_acpi_mcfg_fixups[];
> +
> +struct pci_ecam_ops *pci_mcfg_get_ops(struct acpi_pci_root *root)
> +{
> +	int bus_num = root->secondary.start;
> +	int domain = root->segment;
> +	struct pci_cfg_fixup *f;
> +
> +	if (!mcfg_table)
> +		return &pci_generic_ecam_ops;
> +
> +	/*
> +	 * Match against platform specific quirks and return corresponding
> +	 * CAM ops.
> +	 *
> +	 * First match against PCI topology <domain:bus> then use OEM ID and
> +	 * OEM revision from MCFG table standard header.
> +	 */
> +	for (f = __start_acpi_mcfg_fixups; f < __end_acpi_mcfg_fixups; f++) {
> +		if ((f->domain == domain || f->domain == PCI_MCFG_DOMAIN_ANY) &&
> +		    (f->bus_num == bus_num || f->bus_num == PCI_MCFG_BUS_ANY) &&
> +		    (!strncmp(f->oem_id, mcfg_table->header.oem_id,
> +			      ACPI_OEM_ID_SIZE)) &&
> +		    (!strncmp(f->oem_table_id, mcfg_table->header.oem_table_id,
> +			      ACPI_OEM_TABLE_ID_SIZE)))

This would just be a small convenience, but if the character count used here were

min(strlen(f->oem_id), ACPI_OEM_ID_SIZE)

then the parameters to DECLARE_ACPI_MCFG_FIXUP macro could be substrings and
wouldn't need to be padded out to the full length.

> +			return f->ops;
> +	}
> +	/* No quirks, use ECAM */
> +	return &pci_generic_ecam_ops;
> +}

> diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
> index 7d63a66..088a1da 100644
> --- a/include/linux/pci-acpi.h
> +++ b/include/linux/pci-acpi.h
> @@ -25,6 +25,7 @@ static inline acpi_status pci_acpi_remove_pm_notifier(struct acpi_device *dev)
>  extern phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle);
>  
>  extern phys_addr_t pci_mcfg_lookup(u16 domain, struct resource *bus_res);
> +extern struct pci_ecam_ops *pci_mcfg_get_ops(struct acpi_pci_root *root);
>  
>  static inline acpi_handle acpi_find_root_bridge_handle(struct pci_dev *pdev)
>  {
> @@ -72,6 +73,25 @@ struct acpi_pci_root_ops {
>  	int (*prepare_resources)(struct acpi_pci_root_info *info);
>  };
>  
> +struct pci_cfg_fixup {
> +	struct pci_ecam_ops *ops;
> +	char *oem_id;
> +	char *oem_table_id;
> +	int domain;
> +	int bus_num;
> +};
> +
> +#define PCI_MCFG_DOMAIN_ANY	-1
> +#define PCI_MCFG_BUS_ANY	-1
> +
> +/* Designate a routine to fix up buggy MCFG */
> +#define DECLARE_ACPI_MCFG_FIXUP(ops, oem_id, oem_table_id, dom, bus)	\
> +	static const struct pci_cfg_fixup				\
> +	__mcfg_fixup_##oem_id##oem_table_id##dom##bus			\

I'm not entirely sure that this is the right fix--I'm pretty blindly
following a GCC documentation suggestion [1]--but removing the first two
preprocessor concatenation operators "##" solved the following build error
for me.

include/linux/pci-acpi.h:90:2: error: pasting "__mcfg_fixup_" and ""QCOM"" does not give a valid preprocessing token
  __mcfg_fixup_##oem_id##oem_table_id##dom##bus   \
  ^
arch/arm64/kernel/pci.c:225:1: note: in expansion of macro ‘DECLARE_ACPI_MCFG_FIXUP’
 DECLARE_ACPI_MCFG_FIXUP(&pci_32b_ecam_ops, "QCOM", "QDF2432", PCI_MCFG_DOMAIN_ANY, PCI_MCFG_BUS_ANY);
 ^
arch/arm64/kernel/pci.c:225:44: error: pasting ""QCOM"" and ""QDF2432"" does not give a valid preprocessing token
 DECLARE_ACPI_MCFG_FIXUP(&pci_32b_ecam_ops, "QCOM", "QDF2432", PCI_MCFG_DOMAIN_ANY, PCI_MCFG_BUS_ANY);
                                            ^
include/linux/pci-acpi.h:90:17: note: in definition of macro ‘DECLARE_ACPI_MCFG_FIXUP’
  __mcfg_fixup_##oem_id##oem_table_id##dom##bus   \
                 ^
arch/arm64/kernel/pci.c:225:52: error: pasting ""QDF2432"" and "PCI_MCFG_DOMAIN_ANY" does not give a valid preprocessi
ng token
 DECLARE_ACPI_MCFG_FIXUP(&pci_32b_ecam_ops, "QCOM", "QDF2432", PCI_MCFG_DOMAIN_ANY, PCI_MCFG_BUS_ANY);
                                                    ^
include/linux/pci-acpi.h:90:25: note: in definition of macro ‘DECLARE_ACPI_MCFG_FIXUP’
  __mcfg_fixup_##oem_id##oem_table_id##dom##bus   \
                         ^
arch/arm64/kernel/pci.c:225:44: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before string constant
 DECLARE_ACPI_MCFG_FIXUP(&pci_32b_ecam_ops, "QCOM", "QDF2432", PCI_MCFG_DOMAIN_ANY, PCI_MCFG_BUS_ANY);
                                            ^
include/linux/pci-acpi.h:90:17: note: in definition of macro ‘DECLARE_ACPI_MCFG_FIXUP’
  __mcfg_fixup_##oem_id##oem_table_id##dom##bus   \
                 ^
make[1]: *** [arch/arm64/kernel/pci.o] Error 1
make: *** [arch/arm64/kernel] Error 2

1. https://gcc.gnu.org/onlinedocs/cpp/Concatenation.html#Concatenation

> +	__used	__attribute__((__section__(".acpi_fixup_mcfg"),		\
> +				aligned((sizeof(void *))))) =		\
> +	{ ops, oem_id, oem_table_id, dom, bus };
> +
>  extern int acpi_pci_probe_root_resources(struct acpi_pci_root_info *info);
>  extern struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
>  					    struct acpi_pci_root_ops *ops,
> 

Thanks,
Cov

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