Tidy up adjustable ws2812 timing (#15299)

drivers/ws2812.h

@@ -17,11 +17,41 @@
 
 #include "quantum/color.h"
 
+/*
+ * The WS2812 datasheets define T1H 900ns, T0H 350ns, T1L 350ns, T0L 900ns. Hence, by default, these
+ * are chosen to be conservative and avoid problems rather than for maximum throughput; in the code,
+ * this is done by default using a WS2812_TIMING parameter that accounts for the whole window (1250ns)
+ * and defining T1H and T0H; T1L and T0L are obtained by subtracting their low counterparts from the window.
+ *
+ * However, there are certain "WS2812"-like LEDs, like the SK6812s, which work in a similar
+ * communication topology but use different timings for the window and the T1L, T1H, T0L and T0H.
+ * This means that, albeit the same driver being applicable, the timings must be adapted.
+ */
+
+#ifndef WS2812_TIMING
+#    define WS2812_TIMING 1250
+#endif
+
+#ifndef WS2812_T1H
+#    define WS2812_T1H 900  // Width of a 1 bit in ns
+#endif
+
+#ifndef WS2812_T1L
+#    define WS2812_T1L (WS2812_TIMING - WS2812_T1H)  // Width of a 1 bit in ns
+#endif
+
+#ifndef WS2812_T0H
+#    define WS2812_T0H 350  // Width of a 0 bit in ns
+#endif
+
+#ifndef WS2812_T0L
+#    define WS2812_T0L (WS2812_TIMING - WS2812_T0H)  // Width of a 0 bit in ns
+#endif
+
 /*
  * Older WS2812s can handle a reset time (TRST) of 50us, but recent
  * component revisions require a minimum of 280us.
  */
-
 #if !defined(WS2812_TRST_US)
 #    define WS2812_TRST_US 280
 #endif