Re: [RFC PATCH v3 1/2] ACPI/PCI: Check platform specific ECAM quirks

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Wed, Jun 15, 2016 at 11:34:10AM -0400, Christopher Covington wrote:
> From: Tomasz Nowicki <tn@semihalf.com>
> 
> Some platforms may not be fully compliant with the generic PCI config
> operations. For these cases we implement a way to use custom map and
> accessor functions. The algorithm traverses the available quirk list,
> matches against <oem_id, oem_table_id, oem_revision, domain, bus number>
> tuples and returns corresponding PCI config ops. oem_id, oem_table_id, and
> oem_revision come from the MCFG table standard header. All quirks can be
> defined using the DECLARE_ACPI_MCFG_FIXUP() macro and are kept self
> contained. Example:
> 
> /* Custom PCI config ops */
> static struct pci_generic_ecam_ops foo_pci_ops = {
> 	.bus_shift	= 24,
> 	.pci_ops = {
> 		.map_bus = pci_ecam_map_bus,
> 		.read = foo_ecam_config_read,
> 		.write = foo_ecam_config_write,
> 	}
> };
> 
> DECLARE_ACPI_MCFG_FIXUP(&foo_pci_ops, "OEM", "TABLE-ID", <revision>,
> 			<domain_nr>, <bus_nr>);
> 
> Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
> Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
> Signed-off-by: Christopher Covington <cov@codeaurora.org>
> 
> ---
> 
> Changes from v2 to v3:
> * Match against all three of oem_id, oem_table_id, and oem_revision.
> * Perform substring match, so padding oem_id and oem_table_id isn't
>   required. (Using min_t() thanks to Duc Dang's suggestion.)
> * Print when quirk matched.
> * Use __UNIQUE_ID() macro to generate a valid, unique symbol name even
>   when OEM and table IDs contain characters such as dash "-".
> * Move extern declaration to header and fix spelling and formatting to
>   satisfy checkpatch/coding style.
> ---
>  drivers/acpi/pci_mcfg.c           | 49 ++++++++++++++++++++++++++++++++++++---
>  include/asm-generic/vmlinux.lds.h |  7 ++++++
>  include/linux/pci-acpi.h          | 24 +++++++++++++++++++
>  3 files changed, 77 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c
> index b5b376e..2a5d3dd 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;

Tomasz had to add an MCFG cache in its final v9 since it is not
safe to stash a pointer here, which probably means you will have
to stash oem_id and oem_table_id to carry out the fixup match
instead of relying on the header retrieved through the stashed
pointer.

Lorenzo

>  /* Structure to hold entries from the MCFG table */
>  struct mcfg_entry {
> @@ -35,6 +39,46 @@ struct mcfg_entry {
>  /* List to save MCFG entries */
>  static LIST_HEAD(pci_mcfg_list);
>  
> +static bool pci_mcfg_fixup_match(struct pci_cfg_fixup *f,
> +				 struct acpi_table_header *h)
> +{
> +	int olen = min_t(u8, strlen(f->oem_id), ACPI_OEM_ID_SIZE);
> +	int tlen = min_t(u8, strlen(f->oem_table_id), ACPI_OEM_TABLE_ID_SIZE);
> +
> +	return (!strncmp(f->oem_id, h->oem_id, olen) &&
> +		!strncmp(f->oem_table_id, h->oem_table_id, tlen) &&
> +		f->oem_revision == h->oem_revision);
> +}
> +
> +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, OEM
> +	 * table 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) &&
> +		    pci_mcfg_fixup_match(f, &mcfg_table->header)) {
> +			pr_info("Handling %s %s r%d PCI MCFG quirks\n",
> +				f->oem_id, f->oem_table_id, f->oem_revision);
> +			return f->ops;
> +		}
> +	}
> +	/* No quirks, use ECAM */
> +	return &pci_generic_ecam_ops;
> +}
> +
>  phys_addr_t pci_mcfg_lookup(u16 seg, struct resource *bus_res)
>  {
>  	struct mcfg_entry *e;
> @@ -54,7 +98,6 @@ phys_addr_t pci_mcfg_lookup(u16 seg, struct resource *bus_res)
>  
>  static __init int pci_mcfg_parse(struct acpi_table_header *header)
>  {
> -	struct acpi_table_mcfg *mcfg;
>  	struct acpi_mcfg_allocation *mptr;
>  	struct mcfg_entry *e, *arr;
>  	int i, n;
> @@ -64,8 +107,8 @@ static __init int pci_mcfg_parse(struct acpi_table_header *header)
>  
>  	n = (header->length - sizeof(struct acpi_table_mcfg)) /
>  					sizeof(struct acpi_mcfg_allocation);
> -	mcfg = (struct acpi_table_mcfg *)header;
> -	mptr = (struct acpi_mcfg_allocation *) &mcfg[1];
> +	mcfg_table = (struct acpi_table_mcfg *)header;
> +	mptr = (struct acpi_mcfg_allocation *) &mcfg_table[1];
>  
>  	arr = kcalloc(n, sizeof(*arr), GFP_KERNEL);
>  	if (!arr)
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 6a67ab9..43604fc 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -300,6 +300,13 @@
>  		VMLINUX_SYMBOL(__end_pci_fixups_suspend_late) = .;	\
>  	}								\
>  									\
> +	/* ACPI MCFG quirks */						\
> +	.acpi_fixup        : AT(ADDR(.acpi_fixup) - LOAD_OFFSET) {	\
> +		VMLINUX_SYMBOL(__start_acpi_mcfg_fixups) = .;		\
> +		*(.acpi_fixup_mcfg)					\
> +		VMLINUX_SYMBOL(__end_acpi_mcfg_fixups) = .;		\
> +	}								\
> +									\
>  	/* Built-in firmware blobs */					\
>  	.builtin_fw        : AT(ADDR(.builtin_fw) - LOAD_OFFSET) {	\
>  		VMLINUX_SYMBOL(__start_builtin_fw) = .;			\
> diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
> index 7d63a66..dac851b 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 +73,29 @@ 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;
> +	u32 oem_revision;
> +	int domain;
> +	int bus_num;
> +};
> +
> +extern struct pci_cfg_fixup __start_acpi_mcfg_fixups[];
> +extern struct pci_cfg_fixup __end_acpi_mcfg_fixups[];
> +
> +#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, table, rev, dom, bus)	\
> +	static const struct pci_cfg_fixup			\
> +	__UNIQUE_ID(mcfg_fixup_)				\
> +	__used	__attribute__((__section__(".acpi_fixup_mcfg"),	\
> +				aligned((sizeof(void *))))) =	\
> +	{ ops, oem, table, rev, 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,
> -- 
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