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

[Gabriele Paoloni <gabriele.paoloni@huawei.com>]

Hi Tomasz, Jon

> -----Original Message-----
> From: liudongdong (C)
> Sent: 13 June 2016 14:02
> To: helgaas@kernel.org; arnd@arndb.de; will.deacon@arm.com;
> catalin.marinas@arm.com; rafael@kernel.org; hanjun.guo@linaro.org;
> Lorenzo.Pieralisi@arm.com; okaya@codeaurora.org; jchandra@broadcom.com;
> tn@semihalf.com
> Cc: robert.richter@caviumnetworks.com; mw@semihalf.com;
> Liviu.Dudau@arm.com; ddaney@caviumnetworks.com; Wangyijing;
> Suravee.Suthikulpanit@amd.com; msalter@redhat.com; linux-
> pci@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
> acpi@vger.kernel.org; linux-kernel@vger.kernel.org; linaro-
> acpi@lists.linaro.org; jcm@redhat.com; andrea.gallo@linaro.org;
> dhdang@apm.com; jeremy.linton@arm.com; liudongdong (C);
> cov@codeaurora.org; Gabriele Paoloni; Chenxin (Charles); Linuxarm
> Subject: [RFC PATCH V2 1/2] ACPI/PCI: Match PCI config space accessors
> against platfrom specific ECAM quirks
> 
> From: Tomasz Nowicki <tn@semihalf.com>
> 
> Some platforms may not be fully compliant with generic set of PCI
> config
> accessors. For these cases we implement the way to overwrite accessors
> set. Algorithm traverses available quirk list, matches against
> <oem_id, oem_table_id, domain, bus number> tuple and returns
> corresponding
> PCI config ops. oem_id and oem_table_id come from MCFG table standard
> header.
> All quirks can be defined using DECLARE_ACPI_MCFG_FIXUP() macro and
> 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_id_str>, <oem_table_id>,
> <domain_nr>, <bus_nr>);
> 
> Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
> Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
> ---
>  drivers/acpi/pci_mcfg.c           | 41
> ++++++++++++++++++++++++++++++++++++---
>  include/asm-generic/vmlinux.lds.h |  7 +++++++
>  include/linux/pci-acpi.h          | 20 +++++++++++++++++++
>  3 files changed, 65 insertions(+), 3 deletions(-)
> 
> 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)))

As you can see here Liudongdong has replaced oem_revision with
oem_table_id.

Now it seems that there are some platforms that have already shipped
using a matching based on the oem_revision (right Jon?)

However I guess that if in FW they have defined oem_table_id properly
they should be able to use this mechanism without needing to a FW update.

Can these vendors confirm this?

Tomasz do you think this can work for Cavium Thunder?

Thanks

Gab


> +			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 +90,6 @@ 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 +99,8 @@ 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..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			\
> +	__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,
> --
> 1.9.1