[RFC/RFT 4/6] PCI: rockchip-dwc: add pcie bifurcation

[Frank Wunderlich <linux@xxxxxxxxx>]

From: Frank Wunderlich <frank-w@xxxxxxxxxxxxxxx>

PCIe Lanes can be split to 2 slots with bifurcation.
Add support for this in existing pcie driver.

Co-developed-by: Peter Geis <pgwipeout@xxxxxxxxx>
Signed-off-by: Frank Wunderlich <frank-w@xxxxxxxxxxxxxxx>
---
 drivers/pci/controller/dwc/pcie-dw-rockchip.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
index 863374604fb1..1b0c2115b32e 100644
--- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
+++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
@@ -20,6 +20,7 @@
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/reset.h>
+#include <linux/phy/pcie.h>
 
 #include "pcie-designware.h"
 
@@ -59,6 +60,7 @@ struct rockchip_pcie {
 	struct regulator                *vpcie3v3;
 	struct irq_domain		*irq_domain;
 	raw_spinlock_t			irq_lock;
+	bool				bifurcation;
 };
 
 static int rockchip_pcie_readl_apb(struct rockchip_pcie *rockchip,
@@ -273,6 +275,12 @@ static int rockchip_pcie_phy_init(struct rockchip_pcie *rockchip)
 		return dev_err_probe(dev, PTR_ERR(rockchip->phy),
 				     "missing PHY\n");
 
+	if (rockchip->bifurcation) {
+		ret = phy_set_mode_ext(rockchip->phy, PHY_MODE_PCIE, PHY_MODE_PCIE_BIFURCATION);
+		if (ret)
+			return ret;
+	}
+
 	ret = phy_init(rockchip->phy);
 	if (ret < 0)
 		return ret;
@@ -345,6 +353,9 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
 		}
 	}
 
+	if (device_property_read_bool(dev, "rockchip,bifurcation"))
+		rockchip->bifurcation = true;
+
 	ret = rockchip_pcie_phy_init(rockchip);
 	if (ret)
 		goto disable_regulator;
-- 
2.25.1