Re: [Linaro-acpi] [RFC PATCH 1/3] pci, acpi: Match PCI config space accessors against platfrom specific ECAM quirks.

Hi Tomasz,

Thanks for your work on this.

On 06/02/2016 04:41 AM, Tomasz Nowicki wrote:

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_rev, domain, bus number> tuple and returns corresponding PCI config ops. oem_id and oem_rev 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_rev>, <domain_nr>, <bus_nr>);

Signed-off-by: Tomasz Nowicki tn@semihalf.com

drivers/acpi/pci_mcfg.c | 32 ++++++++++++++++++++++++++++++++ include/asm-generic/vmlinux.lds.h | 7 +++++++ include/linux/pci-acpi.h | 19 +++++++++++++++++++ 3 files changed, 58 insertions(+)

diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c index 1847f74..f3d4570 100644 --- a/drivers/acpi/pci_mcfg.c +++ b/drivers/acpi/pci_mcfg.c @@ -22,11 +22,43 @@ #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; static int mcfg_entries; +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)) &&
  

•     (f->oem_revision == mcfg_table->header.oem_revision))
  

Is this more likely to be updated between quirky and fixed platforms than oem_table_id? What do folks think about using oem_table_id instead of, or in addition to, oem_revision?

In case these details are helpful, here was my simple prototype of an MCFG based approach:

https://codeaurora.org/cgit/quic/server/kernel/commit/?h=cov/4.7-rc1-testing... https://codeaurora.org/cgit/quic/server/kernel/commit/?h=cov/4.7-rc1-testing...

Thanks, Cov