[PATCH V4 21/23] 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 <platform ID (DMI), domain, bus number> tuple and
returns corresponding accessors. All quirks can be defined using:
DECLARE_ACPI_MCFG_FIXUP() and kept self contained. Example,

static const struct dmi_system_id foo_dmi[] = {
        {
                .ident = "<Platform ident string>",
                .callback = <handler>,
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "<system vendor>"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "<product name>"),
                        DMI_MATCH(DMI_PRODUCT_VERSION, "product version"),
                },
        },
        { }
};

static struct pci_ops foo_ecam_pci_ops = {
        .map_bus = pci_mcfg_dev_base,
        .read = foo_ecam_config_read,
        .write = foo_ecam_config_write,
};
DECLARE_ACPI_MCFG_FIXUP(foo_dmi, NULL, &foo_ecam_pci_ops, <domain_nr>, <bus_nr>);

More custom (non-DMI) matching can be done via an extra call.
Note that there is possibility to assign quirk related private data to
root->sysdata which will be available along read/wriate accessor, example:

static int boo_match(struct pci_mcfg_fixup *fixup, struct acpi_pci_root *root)
{
        return [condition] ? 1 : 0;
}

int boo_ecam_config_read(struct pci_bus *bus, unsigned int devfn,
                          int where, int size, u32 *val)
{
        struct acpi_pci_root *root = bus->sysdata;
        struct boo_priv_data *boo_data = root->sysdata;

        [..]
}

static struct pci_ops boo_ecam_pci_ops = {
	.map_bus = pci_mcfg_dev_base,
	.read = boo_ecam_config_read,
	.write = boo_ecam_config_write,
};
DECLARE_ACPI_MCFG_FIXUP(NULL, boo_match, &boo_ecam_pci_ops, <domain_nr>, <bus_nr>);

Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
Tested-by: Duc Dang <dhdang@apm.com>
Tested-by: Dongdong Liu <liudongdong3@huawei.com>
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Tested-by: Graeme Gregory <graeme.gregory@linaro.org>
Tested-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/acpi/mcfg.c               | 33 +++++++++++++++++++++++++++++++--
 include/acpi/acpi_bus.h           |  1 +
 include/asm-generic/vmlinux.lds.h |  7 +++++++
 include/linux/ecam.h              | 18 ++++++++++++++++++
 4 files changed, 57 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/mcfg.c b/drivers/acpi/mcfg.c
index dfc2d14..4663f70 100644
--- a/drivers/acpi/mcfg.c
+++ b/drivers/acpi/mcfg.c
@@ -8,6 +8,7 @@
  */
 
 #include <linux/acpi.h>
+#include <linux/dmi.h>
 #include <linux/ecam.h>
 #include <linux/pci.h>
 #include <linux/pci-acpi.h>
@@ -34,6 +35,29 @@ int __weak raw_pci_write(unsigned int domain, unsigned int bus,
 	return PCIBIOS_DEVICE_NOT_FOUND;
 }
 
+extern struct pci_mcfg_fixup __start_acpi_mcfg_fixups[];
+extern struct pci_mcfg_fixup __end_acpi_mcfg_fixups[];
+
+static struct pci_ops *pci_mcfg_check_quirks(struct acpi_pci_root *root)
+{
+	struct pci_mcfg_fixup *f;
+	int bus_num = root->secondary.start;
+	int domain = root->segment;
+
+	/*
+	 * 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;
+	}
+	return NULL;
+}
+
 void __iomem *
 pci_mcfg_dev_base(struct pci_bus *bus, unsigned int devfn, int offset)
 {
@@ -56,10 +80,15 @@ static struct pci_ops default_pci_mcfg_ops = {
 
 struct pci_ops *pci_mcfg_get_ops(struct acpi_pci_root *root)
 {
+	struct pci_ops *pci_mcfg_ops_quirk;
+
 	/*
-	 * TODO: Match against platform specific quirks and return
-	 * corresponding PCI config space accessor set.
+	 * Match against platform specific quirks and return corresponding
+	 * PCI config space accessor set.
 	 */
+	pci_mcfg_ops_quirk = pci_mcfg_check_quirks(root);
+	if (pci_mcfg_ops_quirk)
+		return pci_mcfg_ops_quirk;
 
 	return &default_pci_mcfg_ops;
 }
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 14362a8..0fc6f13 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -556,6 +556,7 @@ struct acpi_pci_root {
 	struct pci_bus *bus;
 	u16 segment;
 	struct resource secondary;	/* downstream bus range */
+	void *sysdata;
 
 	u32 osc_support_set;	/* _OSC state of support bits */
 	u32 osc_control_set;	/* _OSC state of control bits */
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index c4bd0e2..c93fc97 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/ecam.h b/include/linux/ecam.h
index e0f322e..21215be 100644
--- a/include/linux/ecam.h
+++ b/include/linux/ecam.h
@@ -20,6 +20,24 @@ struct pci_mmcfg_region {
 	bool hot_added;
 };
 
+struct pci_mcfg_fixup {
+	const struct dmi_system_id *system;
+	int (*match)(struct pci_mcfg_fixup *, struct acpi_pci_root *);
+	struct pci_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_mcfg_fixup __mcfg_fixup_##system##dom##bus\
+	 __used	__attribute__((__section__(".acpi_fixup_mcfg"),		\
+				aligned((sizeof(void *))))) =		\
+	{ system, match, ops, dom, bus };
+
 struct pci_mmcfg_region *pci_mmconfig_lookup(int segment, int bus);
 struct pci_mmcfg_region *pci_mmconfig_alloc(int segment, int start,
 						   int end, u64 addr);
-- 
1.9.1