[PATCH V6 11/13] pci, acpi: Match PCI config space accessors against platfrom specific quirks.

[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 prior to PCI buses enumeration. Algorithm traverses available quirk
list, matches against <DMI ID (optional), domain, bus number> tuple and
an extra match call and returns corresponding PCI config ops.
All quirks can be defined using:
DECLARE_ACPI_MCFG_FIXUP() macro and kept self contained. Example:

/* Additional DMI platform identification (optional) */
static const struct dmi_system_id foo_dmi[] = {
        {
                .ident = "<Platform ident string>",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "<system vendor>"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "<product name>"),
                        DMI_MATCH(DMI_PRODUCT_VERSION, "product version"),
                },
        },
        { }
};

/* Custom PCI config ops */
static struct pci_generic_ecam_ops foo_pci_ops = {
	.bus_shift	= 24,
	.pci_ops = {
		.map_bus = pci_mcfg_dev_base,
		.read = foo_ecam_config_read,
		.write = foo_ecam_config_write,
	}
};

static int foo_match(struct pci_mcfg_fixup *fixup, struct acpi_pci_root *root)
{
	if (additional platform identification)
	        return true;
	return false;
}

DECLARE_ACPI_MCFG_FIXUP(foo_dmi, foo_init, &foo_root_ops, <domain_nr>, <bus_nr>);

Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
---
 drivers/acpi/pci_gen_host.c       | 30 +++++++++++++++++++++++++++++-
 include/asm-generic/vmlinux.lds.h |  7 +++++++
 include/linux/pci-acpi.h          | 18 ++++++++++++++++++
 3 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/pci_gen_host.c b/drivers/acpi/pci_gen_host.c
index fd360b5..e55dfca 100644
--- a/drivers/acpi/pci_gen_host.c
+++ b/drivers/acpi/pci_gen_host.c
@@ -11,6 +11,8 @@
  * You should have received a copy of the GNU General Public License
  * version 2 (GPLv2) along with this source code.
  */
+
+#include <linux/dmi.h>
 #include <linux/kernel.h>
 #include <linux/pci.h>
 #include <linux/pci-acpi.h>
@@ -54,6 +56,32 @@ static struct mcfg_entry *pci_mcfg_lookup(u16 seg, u8 bus_start)
 	return NULL;
 }
 
+extern struct pci_cfg_fixup __start_acpi_mcfg_fixups[];
+extern struct pci_cfg_fixup __end_acpi_mcfg_fixups[];
+
+static struct pci_generic_ecam_ops *pci_acpi_get_ops(struct acpi_pci_root *root)
+{
+	int bus_num = root->secondary.start;
+	int domain = root->segment;
+	struct pci_cfg_fixup *f;
+
+	/*
+	 * Match against platform specific quirks and return corresponding
+	 * CAM ops.
+	 *
+	 * First match against PCI topology <domain:bus> then use DMI or
+	 * custom match handler.
+	 */
+	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) &&
+		    (f->system ? dmi_check_system(f->system) : 1) &&
+		    (f->match ? f->match(f, root) : 1))
+			return f->ops;
+	}
+	/* No quirks, use ECAM */
+	return &pci_generic_ecam_default_ops;
+}
 
 /*
  * Lookup the bus range for the domain in MCFG, and set up config space
@@ -95,7 +123,7 @@ static int pci_acpi_setup_ecam_mapping(struct acpi_pci_root *root,
 	}
 
 	cfg = pci_generic_ecam_create(&root->device->dev, addr, bus_start,
-				      bus_end, &pci_generic_ecam_default_ops);
+				      bus_end, pci_acpi_get_ops(root));
 	if (IS_ERR(cfg)) {
 		err = PTR_ERR(cfg);
 		pr_err("%04x:%02x-%02x error %d mapping CAM\n", seg,
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 339125b..c53b6b7 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -298,6 +298,13 @@
 		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 a72e22d..9545988 100644
--- a/include/linux/pci-acpi.h
+++ b/include/linux/pci-acpi.h
@@ -71,6 +71,24 @@ struct acpi_pci_root_ops {
 	int (*prepare_resources)(struct acpi_pci_root_info *info);
 };
 
+struct pci_cfg_fixup {
+	const struct dmi_system_id *system;
+	bool (*match)(struct pci_cfg_fixup *, struct acpi_pci_root *);
+	struct pci_generic_ecam_ops *ops;
+	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(system, match, ops, dom, bus)		\
+	static const struct pci_cfg_fixup __mcfg_fixup_##system##dom##bus\
+	 __used	__attribute__((__section__(".acpi_fixup_mcfg"),		\
+				aligned((sizeof(void *))))) =		\
+	{ system, match, ops, 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