PCI: Add support for Enhanced Allocation devices

Add support for devices using Enhanced Allocation entries instead of BARs.
This allows the kernel to parse the EA Extended Capability structure in PCI
config space and claim the BAR-equivalent resources.

See https://pcisig.com/sites/default/files/specification_documents/ECN_Enhanced_Allocation_23_Oct_2014_Final.pdf

[bhelgaas: add spec URL, s/pci_ea_set_flags/pci_ea_flags/, consolidate
declarations, print unknown property in hex to match spec]
Signed-off-by: Sean O. Stalley <sean.stalley@intel.com>
[david.daney@cavium.com: Add more support/checking for Entry Properties,
allow EA behind bridges, rewrite some error messages.]
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/pci.c

@@ -2148,6 +2148,179 @@ void pci_pm_init(struct pci_dev *dev)
 	}
 }
 
+static unsigned long pci_ea_flags(struct pci_dev *dev, u8 prop)
+{
+	unsigned long flags = IORESOURCE_PCI_FIXED;
+
+	switch (prop) {
+	case PCI_EA_P_MEM:
+	case PCI_EA_P_VF_MEM:
+		flags |= IORESOURCE_MEM;
+		break;
+	case PCI_EA_P_MEM_PREFETCH:
+	case PCI_EA_P_VF_MEM_PREFETCH:
+		flags |= IORESOURCE_MEM | IORESOURCE_PREFETCH;
+		break;
+	case PCI_EA_P_IO:
+		flags |= IORESOURCE_IO;
+		break;
+	default:
+		return 0;
+	}
+
+	return flags;
+}
+
+static struct resource *pci_ea_get_resource(struct pci_dev *dev, u8 bei,
+					    u8 prop)
+{
+	if (bei <= PCI_EA_BEI_BAR5 && prop <= PCI_EA_P_IO)
+		return &dev->resource[bei];
+	else if (bei == PCI_EA_BEI_ROM)
+		return &dev->resource[PCI_ROM_RESOURCE];
+	else
+		return NULL;
+}
+
+/* Read an Enhanced Allocation (EA) entry */
+static int pci_ea_read(struct pci_dev *dev, int offset)
+{
+	struct resource *res;
+	int ent_size, ent_offset = offset;
+	resource_size_t start, end;
+	unsigned long flags;
+	u32 dw0, base, max_offset;
+	u8 prop;
+	bool support_64 = (sizeof(resource_size_t) >= 8);
+
+	pci_read_config_dword(dev, ent_offset, &dw0);
+	ent_offset += 4;
+
+	/* Entry size field indicates DWORDs after 1st */
+	ent_size = ((dw0 & PCI_EA_ES) + 1) << 2;
+
+	if (!(dw0 & PCI_EA_ENABLE)) /* Entry not enabled */
+		goto out;
+
+	prop = PCI_EA_PP(dw0);
+	/*
+	 * If the Property is in the reserved range, try the Secondary
+	 * Property instead.
+	 */
+	if (prop > PCI_EA_P_BRIDGE_IO && prop < PCI_EA_P_MEM_RESERVED)
+		prop = PCI_EA_SP(dw0);
+	if (prop > PCI_EA_P_BRIDGE_IO)
+		goto out;
+
+	res = pci_ea_get_resource(dev, PCI_EA_BEI(dw0), prop);
+	if (!res) {
+		dev_err(&dev->dev, "Unsupported EA entry BEI: %u\n",
+			PCI_EA_BEI(dw0));
+		goto out;
+	}
+
+	flags = pci_ea_flags(dev, prop);
+	if (!flags) {
+		dev_err(&dev->dev, "Unsupported EA properties: %#x\n", prop);
+		goto out;
+	}
+
+	/* Read Base */
+	pci_read_config_dword(dev, ent_offset, &base);
+	start = (base & PCI_EA_FIELD_MASK);
+	ent_offset += 4;
+
+	/* Read MaxOffset */
+	pci_read_config_dword(dev, ent_offset, &max_offset);
+	ent_offset += 4;
+
+	/* Read Base MSBs (if 64-bit entry) */
+	if (base & PCI_EA_IS_64) {
+		u32 base_upper;
+
+		pci_read_config_dword(dev, ent_offset, &base_upper);
+		ent_offset += 4;
+
+		flags |= IORESOURCE_MEM_64;
+
+		/* entry starts above 32-bit boundary, can't use */
+		if (!support_64 && base_upper)
+			goto out;
+
+		if (support_64)
+			start |= ((u64)base_upper << 32);
+	}
+
+	end = start + (max_offset | 0x03);
+
+	/* Read MaxOffset MSBs (if 64-bit entry) */
+	if (max_offset & PCI_EA_IS_64) {
+		u32 max_offset_upper;
+
+		pci_read_config_dword(dev, ent_offset, &max_offset_upper);
+		ent_offset += 4;
+
+		flags |= IORESOURCE_MEM_64;
+
+		/* entry too big, can't use */
+		if (!support_64 && max_offset_upper)
+			goto out;
+
+		if (support_64)
+			end += ((u64)max_offset_upper << 32);
+	}
+
+	if (end < start) {
+		dev_err(&dev->dev, "EA Entry crosses address boundary\n");
+		goto out;
+	}
+
+	if (ent_size != ent_offset - offset) {
+		dev_err(&dev->dev,
+			"EA Entry Size (%d) does not match length read (%d)\n",
+			ent_size, ent_offset - offset);
+		goto out;
+	}
+
+	res->name = pci_name(dev);
+	res->start = start;
+	res->end = end;
+	res->flags = flags;
+	dev_printk(KERN_DEBUG, &dev->dev, "EA - BEI %2u, Prop 0x%02x: %pR\n",
+		   PCI_EA_BEI(dw0), prop, res);
+out:
+	return offset + ent_size;
+}
+
+/* Enhanced Allocation Initalization */
+void pci_ea_init(struct pci_dev *dev)
+{
+	int ea;
+	u8 num_ent;
+	int offset;
+	int i;
+
+	/* find PCI EA capability in list */
+	ea = pci_find_capability(dev, PCI_CAP_ID_EA);
+	if (!ea)
+		return;
+
+	/* determine the number of entries */
+	pci_bus_read_config_byte(dev->bus, dev->devfn, ea + PCI_EA_NUM_ENT,
+					&num_ent);
+	num_ent &= PCI_EA_NUM_ENT_MASK;
+
+	offset = ea + PCI_EA_FIRST_ENT;
+
+	/* Skip DWORD 2 for type 1 functions */
+	if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
+		offset += 4;
+
+	/* parse each EA entry */
+	for (i = 0; i < num_ent; ++i)
+		offset = pci_ea_read(dev, offset);
+}
+
 static void pci_add_saved_cap(struct pci_dev *pci_dev,
 	struct pci_cap_saved_state *new_cap)
 {

drivers/pci/pci.h

@@ -78,6 +78,7 @@ bool pci_dev_keep_suspended(struct pci_dev *dev);
 void pci_config_pm_runtime_get(struct pci_dev *dev);
 void pci_config_pm_runtime_put(struct pci_dev *dev);
 void pci_pm_init(struct pci_dev *dev);
+void pci_ea_init(struct pci_dev *dev);
 void pci_allocate_cap_save_buffers(struct pci_dev *dev);
 void pci_free_cap_save_buffers(struct pci_dev *dev);
 

drivers/pci/probe.c

@@ -1598,6 +1598,9 @@ static struct pci_dev *pci_scan_device(struct pci_bus *bus, int devfn)
 
 static void pci_init_capabilities(struct pci_dev *dev)
 {
+	/* Enhanced Allocation */
+	pci_ea_init(dev);
+
 	/* MSI/MSI-X list */
 	pci_msi_init_pci_dev(dev);