[PATCH v3 02/18] PCI: dwc: Factor out the PORT_LINK_DEBUG1 link-up check

[Koichiro Den]

dw_pcie_link_up() reads PORT_LINK_DEBUG1 when the glue driver provides
no .link_up() callback. A callback that needs a platform-specific check
on top of that register would have to duplicate the register read.

Factor the check out into dw_pcie_link_up_debug_check() and export it
for modular glue drivers. pcie-rcar-gen4 will be the first user: its APP
link-up events remain latched after the link goes down, so it has to
combine them with the live PORT_LINK_DEBUG1 state.

No functional change.

Suggested-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxxxx>
Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
---
Changes in v3:
  - New patch, suggested by Marek in the v2 review of patch 2.
    https://lore.kernel.org/r/c038dbd9-7675-43a9-834c-915b6795dd50@xxxxxxxxxxx/

 drivers/pci/controller/dwc/pcie-designware.c | 15 +++++++++++----
 drivers/pci/controller/dwc/pcie-designware.h |  1 +
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index c726aa71c830..49a9ba910ba8 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -817,17 +817,24 @@ int dw_pcie_wait_for_link(struct dw_pcie *pci)
 }
 EXPORT_SYMBOL_GPL(dw_pcie_wait_for_link);
 
-bool dw_pcie_link_up(struct dw_pcie *pci)
+/* Link state from PORT_LINK_DEBUG1: up and not in training */
+bool dw_pcie_link_up_debug_check(struct dw_pcie *pci)
 {
 	u32 val;
 
-	if (pci->ops && pci->ops->link_up)
-		return pci->ops->link_up(pci);
-
 	val = dw_pcie_readl_dbi(pci, PORT_LINK_DEBUG1);
 	return ((val & PORT_LINK_DEBUG1_LINK_UP) &&
 		(!(val & PORT_LINK_DEBUG1_LINK_IN_TRAINING)));
 }
+EXPORT_SYMBOL_GPL(dw_pcie_link_up_debug_check);
+
+bool dw_pcie_link_up(struct dw_pcie *pci)
+{
+	if (pci->ops && pci->ops->link_up)
+		return pci->ops->link_up(pci);
+
+	return dw_pcie_link_up_debug_check(pci);
+}
 EXPORT_SYMBOL_GPL(dw_pcie_link_up);
 
 void dw_pcie_upconfig_setup(struct dw_pcie *pci)
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 419932488280..2ce61709b58c 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -618,6 +618,7 @@ int dw_pcie_write(void __iomem *addr, int size, u32 val);
 u32 dw_pcie_read_dbi(struct dw_pcie *pci, u32 reg, size_t size);
 void dw_pcie_write_dbi(struct dw_pcie *pci, u32 reg, size_t size, u32 val);
 void dw_pcie_write_dbi2(struct dw_pcie *pci, u32 reg, size_t size, u32 val);
+bool dw_pcie_link_up_debug_check(struct dw_pcie *pci);
 bool dw_pcie_link_up(struct dw_pcie *pci);
 void dw_pcie_upconfig_setup(struct dw_pcie *pci);
 int dw_pcie_wait_for_link(struct dw_pcie *pci);
-- 
2.51.0