[PATCH 2/2] PCI: Add support for Enhanced Allocation devices

[Sean O. Stalley]

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

Signed-off-by: Sean O. Stalley <sean.stalley@xxxxxxxxx>
---
 drivers/pci/pci.c   | 219 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/pci/pci.h   |   1 +
 drivers/pci/probe.c |   3 +
 3 files changed, 223 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 0008c95..c8217a8 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2134,6 +2134,225 @@ void pci_pm_init(struct pci_dev *dev)
 	}
 }
 
+static unsigned long pci_ea_set_flags(struct pci_dev *dev, u8 prop)
+{
+	unsigned long flags = IORESOURCE_PCI_FIXED;
+
+	switch (prop) {
+	case PCI_EA_P_MEM:
+		flags |= IORESOURCE_MEM;
+		break;
+	case PCI_EA_P_MEM_PREFETCH:
+		flags |= IORESOURCE_MEM | IORESOURCE_PREFETCH;
+		break;
+	case PCI_EA_P_IO:
+		flags |= IORESOURCE_IO;
+		break;
+	default:
+		dev_warn(&dev->dev, "%s: Property type %x not supported\n",
+			__func__, prop);
+		return 0;
+	}
+
+	return flags;
+}
+
+static struct resource *pci_ea_get_parent_resource(struct pci_dev *dev,
+					struct resource *res)
+{
+	struct resource *parent;
+
+	parent = pci_find_parent_resource(dev, res);
+	if (parent)
+		return parent;
+
+	/* for resources not claimed by a bridge */
+	if (res->flags & IORESOURCE_MEM)
+		return &iomem_resource;
+
+	if (res->flags & IORESOURCE_IO)
+		return &ioport_resource;
+
+	return NULL;
+}
+
+/* claim the memory for this device in the proper location */
+static void pci_ea_claim_resource(struct pci_dev *dev, struct resource *res)
+{
+	struct resource *parent;
+	struct resource *conflict;
+
+	parent = pci_ea_get_parent_resource(dev, res);
+	if (!parent) {
+		dev_warn(&dev->dev, "can't find parent resource for EA entry %s %pR\n",
+			res->name, res);
+		return;
+	}
+
+	/* claim the appropriate resource */
+	conflict = request_resource_conflict(parent, res);
+	if (conflict) {
+		dev_warn(&dev->dev, "can't claim EA entry %s %pR: address conflict with %s %pR\n",
+			 res->name, res, conflict->name, conflict);
+	}
+}
+
+static struct resource *pci_ea_get_resource(struct pci_dev *dev, u8 bei)
+{
+	if (bei <= PCI_STD_RESOURCE_END)
+		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_offset = offset;
+	int ent_size;
+	resource_size_t start;
+	resource_size_t end;
+	unsigned long flags;
+	u32 dw0;
+	u32 base;
+	u32 max_offset;
+	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)) {
+		dev_err(&dev->dev, "%s: Entry not enabled\n", __func__);
+		goto out;
+	}
+
+	res = pci_ea_get_resource(dev, PCI_EA_BEI(dw0));
+	if (!res) {
+		dev_err(&dev->dev, "%s: Unsupported EA entry BEI\n", __func__);
+		goto out;
+	}
+
+	flags = pci_ea_set_flags(dev, PCI_EA_PP(dw0));
+	if (!flags)
+		flags = pci_ea_set_flags(dev, PCI_EA_SP(dw0));
+	if (!flags) {
+		dev_err(&dev->dev, "%s: Entry EA properties not supported\n",
+			__func__);
+		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);
+	}
+
+	dev_dbg(&dev->dev, "%s: start = %pa\n", __func__, &start);
+
+	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);
+	}
+
+	dev_dbg(&dev->dev, "%s: end = %pa\n", __func__, &end);
+
+	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 does not match length read\n"
+			"(Entry Size:%u Length Read:%u)\n",
+			ent_size, ent_offset - offset);
+		goto out;
+	}
+
+	res->name = pci_name(dev);
+	res->start = start;
+	res->end = end;
+	res->flags = flags;
+
+	pci_ea_claim_resource(dev, 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;
+
+	dev_dbg(&dev->dev, "%s: capability found!\n", __func__);
+
+	/* 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;
+		/* TODO: Support fixed bus numbers */
+
+	for (i = 0; i < num_ent; ++i) {
+		/* parse each EA entry */
+		dev_dbg(&dev->dev, "%s: parsing entry %i...\n", __func__, 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)
 {
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 4ff0ff1..92fbef0 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -76,6 +76,7 @@ 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);
 
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index cefd636..4cadf35 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1522,6 +1522,9 @@ 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);
 
-- 
1.9.1

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