[PATCH V2 19/23] acpi, mcfg: Add default PCI config accessors implementation and initial support for related quirks.

[Tomasz Nowicki <tn@semihalf.com>]

We use generic accessors from access.c by default. However, we already
know platforms that need special handling while accessing to PCI config
space. These platforms will need different accessors set matched against
platform ID, domain, bus touple. Therefore we are going to add (in future)
DECLARE_ACPI_MCFG_FIXUP which will register platform specific custom
accessors. For now we let pci_mcfg_get_ops takes domain and bus arguments
and left some space for matching algorithm.

Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
---
 drivers/acpi/mcfg.c      | 30 ++++++++++++++++++++++++++++++
 include/linux/pci-acpi.h |  8 ++++++++
 2 files changed, 38 insertions(+)

diff --git a/drivers/acpi/mcfg.c b/drivers/acpi/mcfg.c
index dca4c4e..a9b2231 100644
--- a/drivers/acpi/mcfg.c
+++ b/drivers/acpi/mcfg.c
@@ -34,6 +34,36 @@ int __weak raw_pci_write(unsigned int domain, unsigned int bus,
 	return PCIBIOS_DEVICE_NOT_FOUND;
 }
 
+void __iomem *
+pci_mcfg_dev_base(struct pci_bus *bus, unsigned int devfn, int offset)
+{
+	struct pci_mmcfg_region *cfg;
+
+	cfg = pci_mmconfig_lookup(pci_domain_nr(bus), bus->number);
+	if (cfg && cfg->virt)
+		return cfg->virt +
+			(PCI_MMCFG_BUS_OFFSET(bus->number) | (devfn << 12)) +
+			offset;
+	return NULL;
+}
+
+/* Default generic PCI config accessors */
+static struct pci_ops default_pci_mcfg_ops = {
+	.map_bus = pci_mcfg_dev_base,
+	.read = pci_generic_config_read,
+	.write = pci_generic_config_write,
+};
+
+struct pci_ops *pci_mcfg_get_ops(int domain, int bus)
+{
+	/*
+	 * TODO: Match against platform specific quirks and return
+	 * corresponding PCI config space accessor set.
+	 */
+
+	return &default_pci_mcfg_ops;
+}
+
 int __init acpi_parse_mcfg(struct acpi_table_header *header)
 {
 	struct acpi_table_mcfg *mcfg;
diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
index c277415..3790197 100644
--- a/include/linux/pci-acpi.h
+++ b/include/linux/pci-acpi.h
@@ -82,10 +82,18 @@ void acpi_pci_remove_bus(struct pci_bus *bus);
 #ifdef	CONFIG_PCI_MMCONFIG
 int pci_mmcfg_setup_map(struct acpi_pci_root_info *ci);
 void pci_mmcfg_teardown_map(struct acpi_pci_root_info *ci);
+struct pci_ops *pci_mcfg_get_ops(int domain, int bus);
+void __iomem *
+pci_mcfg_dev_base(struct pci_bus *bus, unsigned int devfn, int offset);
 #else
 static inline int pci_mmcfg_setup_map(struct acpi_pci_root_info *ci)
 { return 0; }
 static inline void pci_mmcfg_teardown_map(struct acpi_pci_root_info *ci) { }
+static inline struct pci_ops *pci_mcfg_get_ops(int domain, int bus)
+{ return NULL; }
+void __iomem *
+pci_mcfg_dev_base(struct pci_bus *bus, unsigned int devfn, int offset)
+{ return NULL; }
 #endif
 
 #ifdef	CONFIG_ACPI_PCI_SLOT
-- 
1.9.1