debugcc: support setting xo_div4 custom value

Some xo require special value to set it to /4 divisor. Introduce
xo_div4_val to handle this special implementation.

Signed-off-by: Christian Marangi <[email protected]>

Author: Ansuel

debugcc.c

@@ -122,7 +122,10 @@ unsigned long measure_gcc(const struct measure_clk *clk,
 	unsigned long xo_div4;
 
 	xo_div4 = readl(mux->base + gcc->xo_div4_reg);
-	writel(xo_div4 | 1, mux->base + gcc->xo_div4_reg);
+	if (gcc->xo_div4_val)
+		writel(xo_div4 | gcc->xo_div4_val, mux->base + gcc->xo_div4_reg);
+	else
+		writel(xo_div4 | 1, mux->base + gcc->xo_div4_reg);
 
 	raw_count_short = measure_ticks(gcc, 0x1000);
 	raw_count_full = measure_ticks(gcc, 0x10000);

debugcc.h

@@ -66,6 +66,8 @@ struct gcc_mux {
 	struct debug_mux mux;
 
 	unsigned int xo_div4_reg;
+	unsigned int xo_div4_val;
+
 	unsigned int debug_ctl_reg;
 	unsigned int debug_status_reg;
 };