[U-Boot] [PATCH 4/4 v3] drivers: pci: add API to issue FLR on a PCI function if supported

[Alex Marginean <alexm.osslist@gmail.com>]

Adds dm_pci_flr API that issues a Function Level reset on a PCI-e function,
if FLR is supported.

Signed-off-by: Alex Marginean <alexm.osslist@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
---

Changes in v2:
	- Use kernel PCI_EXP macros for register offsets
Changes in v3:
	- none

 drivers/pci/pci-uclass.c | 24 ++++++++++++++++++++++++
 include/pci.h            | 14 ++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
index 389aec15ce..c74ebf6a76 100644
--- a/drivers/pci/pci-uclass.c
+++ b/drivers/pci/pci-uclass.c
@@ -1494,6 +1494,30 @@ int dm_pci_find_ext_capability(struct udevice *dev, int cap)
 	return dm_pci_find_next_ext_capability(dev, 0, cap);
 }
 
+int dm_pci_flr(struct udevice *dev)
+{
+	int pcie_off;
+	u32 cap;
+
+	/* look for PCI Express Capability */
+	pcie_off = dm_pci_find_capability(dev, PCI_CAP_ID_EXP);
+	if (!pcie_off)
+		return -ENOENT;
+
+	/* check FLR capability */
+	dm_pci_read_config32(dev, pcie_off + PCI_EXP_DEVCAP, &cap);
+	if (!(cap & PCI_EXP_DEVCAP_FLR))
+		return -ENOENT;
+
+	dm_pci_clrset_config16(dev, pcie_off + PCI_EXP_DEVCTL, 0,
+			       PCI_EXP_DEVCTL_BCR_FLR);
+
+	/* wait 100ms, per PCI spec */
+	mdelay(100);
+
+	return 0;
+}
+
 UCLASS_DRIVER(pci) = {
 	.id		= UCLASS_PCI,
 	.name		= "pci",
diff --git a/include/pci.h b/include/pci.h
index 0aab438159..298d0d4355 100644
--- a/include/pci.h
+++ b/include/pci.h
@@ -466,6 +466,12 @@
 #define  PCI_EA_IS_64		0x00000002	/* 64-bit field flag */
 #define  PCI_EA_FIELD_MASK	0xfffffffc	/* For Base & Max Offset */
 
+/* PCI Express capabilities */
+#define PCI_EXP_DEVCAP		4	/* Device capabilities */
+#define  PCI_EXP_DEVCAP_FLR     0x10000000 /* Function Level Reset */
+#define PCI_EXP_DEVCTL		8	/* Device Control */
+#define  PCI_EXP_DEVCTL_BCR_FLR 0x8000  /* Bridge Configuration Retry / FLR */
+
 /* Include the ID list */
 
 #include <pci_ids.h>
@@ -1426,6 +1432,14 @@ int dm_pci_find_next_ext_capability(struct udevice *dev, int start, int cap);
  */
 int dm_pci_find_ext_capability(struct udevice *dev, int cap);
 
+/**
+ * dm_pci_flr() - Perform FLR if the device suppoorts it
+ *
+ * @dev:	PCI device to reset
+ * @return:	0 if OK, -ENOENT if FLR is not supported by dev
+ */
+int dm_pci_flr(struct udevice *dev);
+
 #define dm_pci_virt_to_bus(dev, addr, flags) \
 	dm_pci_phys_to_bus(dev, (virt_to_phys(addr)), (flags))
 #define dm_pci_bus_to_virt(dev, addr, flags, len, map_flags) \
-- 
2.17.1