dt-bindings: clock: thead: Add TH1520 VO clock controller

Add device tree bindings for the TH1520 Video Output (VO) subsystem
clock controller. The VO sub-system manages clock gates for multimedia
components including HDMI, MIPI, and GPU.

Document the VIDEO_PLL requirements for the VO clock controller, which
receives its input from the AP clock controller. The VIDEO_PLL is a
Silicon Creations Sigma-Delta (integer) PLL typically running at 792 MHz
with maximum FOUTVCO of 2376 MHz.

This binding complements the existing AP sub-system clock controller
which manages CPU, DPU, GMAC and TEE PLLs.

Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Acked-by: Conor Dooley <[e-mail]>
Signed-off-by: Michal Wilczynski <[e-mail]>
Reviewed-by: Drew Fustini <[e-mail]>
Signed-off-by: Drew Fustini <[e-mail]>

Documentation/devicetree/bindings/clock/thead,th1520-clk-ap.yaml

···
 
 description: |
   The T-HEAD TH1520 AP sub-system clock controller configures the
-  CPU, DPU, GMAC and TEE PLLs.
+  CPU, DPU, GMAC and TEE PLLs. Additionally the VO subsystem configures
+  the clock gates for the HDMI, MIPI and the GPU.
 
   SoC reference manual
   https://openbeagle.org/beaglev-ahead/beaglev-ahead/-/blob/main/docs/TH1520%20System%20User%20Manual.pdf
···
 
 properties:
   compatible:
-    const: thead,th1520-clk-ap
+    enum:
+      - thead,th1520-clk-ap
+      - thead,th1520-clk-vo
 
   reg:
     maxItems: 1
 
   clocks:
     items:
-      - description: main oscillator (24MHz)
+      - description: |
+          One input clock:
+          - For "thead,th1520-clk-ap": the clock input must be the 24 MHz
+            main oscillator.
+          - For "thead,th1520-clk-vo": the clock input must be the VIDEO_PLL,
+            which is configured by the AP clock controller. According to the
+            TH1520 manual, VIDEO_PLL is a Silicon Creations Sigma-Delta PLL
+            (integer PLL) typically running at 792 MHz (FOUTPOSTDIV), with
+            a maximum FOUTVCO of 2376 MHz.
 
   "#clock-cells":
     const: 1

include/dt-bindings/clock/thead,th1520-clk-ap.h

···
 #define CLK_SRAM3		83
 #define CLK_PLL_GMAC_100M	84
 #define CLK_UART_SCLK		85
+
+/* VO clocks */
+#define CLK_AXI4_VO_ACLK		0
+#define CLK_GPU_MEM			1
+#define CLK_GPU_CORE			2
+#define CLK_GPU_CFG_ACLK		3
+#define CLK_DPU_PIXELCLK0		4
+#define CLK_DPU_PIXELCLK1		5
+#define CLK_DPU_HCLK			6
+#define CLK_DPU_ACLK			7
+#define CLK_DPU_CCLK			8
+#define CLK_HDMI_SFR			9
+#define CLK_HDMI_PCLK			10
+#define CLK_HDMI_CEC			11
+#define CLK_MIPI_DSI0_PCLK		12
+#define CLK_MIPI_DSI1_PCLK		13
+#define CLK_MIPI_DSI0_CFG		14
+#define CLK_MIPI_DSI1_CFG		15
+#define CLK_MIPI_DSI0_REFCLK		16
+#define CLK_MIPI_DSI1_REFCLK		17
+#define CLK_HDMI_I2S			18
+#define CLK_X2H_DPU1_ACLK		19
+#define CLK_X2H_DPU_ACLK		20
+#define CLK_AXI4_VO_PCLK		21
+#define CLK_IOPMP_VOSYS_DPU_PCLK	22
+#define CLK_IOPMP_VOSYS_DPU1_PCLK	23
+#define CLK_IOPMP_VOSYS_GPU_PCLK	24
+#define CLK_IOPMP_DPU1_ACLK		25
+#define CLK_IOPMP_DPU_ACLK		26
+#define CLK_IOPMP_GPU_ACLK		27
+#define CLK_MIPIDSI0_PIXCLK		28
+#define CLK_MIPIDSI1_PIXCLK		29
+#define CLK_HDMI_PIXCLK			30
+
 #endif