[PATCH v6 1/5] dt-bindings: phy: Add PHY_TYPE_EUSB2 definition

[Krishna Kurapati]

eUSB2 (Embedded USB2) is a MIPI Alliance standard for chip-to-chip USB2
signaling. Unlike standard USB2, which uses 3.3V signaling, eUSB2 uses
low-voltage differential signaling (~0.4V) and requires a repeater to
interface with external USB2 ports. Because of these differences, eUSB2
PHY initialization sequences, voltage tuning, and register configuration
are distinct from USB2.

Additionally, eUSB2 targets handle wakeup interrupts differently
depending on device speed when operating in host mode. According to the
eUSB2 specification, remote wakeup signaling in host mode is detected
via different data-line assertions based on the connected device speed:

- Low-speed devices: the host repeater drives eD+ to logic '1' upon
  detecting a K-state on the USB lines during remote wakeup (eUSB2
  spec, Section 5.5.14).
- Full-speed/high-speed devices: the host repeater drives eD- to
  logic '1' upon detecting a K-state during remote wakeup (eUSB2 spec,
   Sections 5.5.15 and 5.5.18).

Since the eUSB2 PHY's DP and DM lines need to be configured differently
from USB2 PHYs, controllers should be able to query the PHY type and
configure wakeup interrupts accordingly.

Add PHY_TYPE_EUSB2 to distinguish eUSB2 PHYs from standard USB2 PHYs.

Signed-off-by: Krishna Kurapati <krishna.kurapati@xxxxxxxxxxxxxxxx>
---
 include/dt-bindings/phy/phy.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/dt-bindings/phy/phy.h b/include/dt-bindings/phy/phy.h
index 979b5dfd8353..555a022c8c0b 100644
--- a/include/dt-bindings/phy/phy.h
+++ b/include/dt-bindings/phy/phy.h
@@ -24,6 +24,7 @@
 #define PHY_TYPE_CPHY		11
 #define PHY_TYPE_USXGMII	12
 #define PHY_TYPE_XAUI		13
+#define PHY_TYPE_EUSB2		14
 
 #define PHY_POL_NORMAL		0
 #define PHY_POL_INVERT		1

-- 
2.34.1