dm: pci: Add APIs to find capability and extended capability

This introduces two new APIs dm_pci_find_capability() and
dm_pci_find_ext_capability() to get PCI capability address and
PCI express extended capability address for a given PCI device.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

1 files changed, 68 insertions, 0 deletions

diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
index 5eb68415cd..e9671d9b76 100644
--- a/drivers/pci/pci-uclass.c
+++ b/drivers/pci/pci-uclass.c
@@ -1320,6 +1320,74 @@ void *dm_pci_map_bar(struct udevice *dev, int bar, int flags)
 	return dm_pci_bus_to_virt(dev, pci_bus_addr, flags, 0, MAP_NOCACHE);
 }
 
+int dm_pci_find_capability(struct udevice *dev, int cap)
+{
+	u16 status;
+	u8 header_type;
+	int ttl = PCI_FIND_CAP_TTL;
+	u8 id;
+	u16 ent;
+	u8 pos;
+
+	dm_pci_read_config16(dev, PCI_STATUS, &status);
+	if (!(status & PCI_STATUS_CAP_LIST))
+		return 0;
+
+	dm_pci_read_config8(dev, PCI_HEADER_TYPE, &header_type);
+	if ((header_type & 0x7f) == PCI_HEADER_TYPE_CARDBUS)
+		pos = PCI_CB_CAPABILITY_LIST;
+	else
+		pos = PCI_CAPABILITY_LIST;
+
+	dm_pci_read_config8(dev, pos, &pos);
+	while (ttl--) {
+		if (pos < PCI_STD_HEADER_SIZEOF)
+			break;
+		pos &= ~3;
+		dm_pci_read_config16(dev, pos, &ent);
+
+		id = ent & 0xff;
+		if (id == 0xff)
+			break;
+		if (id == cap)
+			return pos;
+		pos = (ent >> 8);
+	}
+
+	return 0;
+}
+
+int dm_pci_find_ext_capability(struct udevice *dev, int cap)
+{
+	u32 header;
+	int ttl;
+	int pos = PCI_CFG_SPACE_SIZE;
+
+	/* minimum 8 bytes per capability */
+	ttl = (PCI_CFG_SPACE_EXP_SIZE - PCI_CFG_SPACE_SIZE) / 8;
+
+	dm_pci_read_config32(dev, pos, &header);
+	/*
+	 * If we have no capabilities, this is indicated by cap ID,
+	 * cap version and next pointer all being 0.
+	 */
+	if (header == 0)
+		return 0;
+
+	while (ttl--) {
+		if (PCI_EXT_CAP_ID(header) == cap)
+			return pos;
+
+		pos = PCI_EXT_CAP_NEXT(header);
+		if (pos < PCI_CFG_SPACE_SIZE)
+			break;
+
+		dm_pci_read_config32(dev, pos, &header);
+	}
+
+	return 0;
+}
+
 UCLASS_DRIVER(pci) = {
 	.id		= UCLASS_PCI,
 	.name		= "pci",