drm/i915: Split map_aux_ch() into per-platform arrays

The big switch+if statement mess in map_aux_ch() is
illegible. Split up into cleaner per-platform arrays
like we already have for the gmbus pins.

We use enum aux_ch as the index and the VBT thing as
the value. Slightly non-intuitive perhaps but if we
did it the other way around we'd have problems with
AUX_CH_A being zero, and thus any non-populated
element would look like AUX_CH_A.

v2: flip the index vs. value around

TODO: Didn't bother with the platform variants beyond the
      ones that really need remapping, which means if the
      VBT is bogus we end up with a nonexistent aux ch.
      Might be nice to check this a bit better.
      Yet another bitmask in device info?
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230509160206.25971-1-ville.syrjala@linux.intel.comReviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>

drivers/gpu/drm/i915/display/intel_bios.c

@@ -3578,84 +3578,82 @@ bool intel_bios_get_dsc_params(struct intel_encoder *encoder,
 	return false;
 }
 
+static const u8 adlp_aux_ch_map[] = {
+	[AUX_CH_A] = DP_AUX_A,
+	[AUX_CH_B] = DP_AUX_B,
+	[AUX_CH_C] = DP_AUX_C,
+	[AUX_CH_D_XELPD] = DP_AUX_D,
+	[AUX_CH_E_XELPD] = DP_AUX_E,
+	[AUX_CH_USBC1] = DP_AUX_F,
+	[AUX_CH_USBC2] = DP_AUX_G,
+	[AUX_CH_USBC3] = DP_AUX_H,
+	[AUX_CH_USBC4] = DP_AUX_I,
+};
+
+/*
+ * ADL-S VBT uses PHY based mapping. Combo PHYs A,B,C,D,E
+ * map to DDI A,TC1,TC2,TC3,TC4 respectively.
+ */
+static const u8 adls_aux_ch_map[] = {
+	[AUX_CH_A] = DP_AUX_A,
+	[AUX_CH_USBC1] = DP_AUX_B,
+	[AUX_CH_USBC2] = DP_AUX_C,
+	[AUX_CH_USBC3] = DP_AUX_D,
+	[AUX_CH_USBC4] = DP_AUX_E,
+};
+
+/*
+ * RKL/DG1 VBT uses PHY based mapping. Combo PHYs A,B,C,D
+ * map to DDI A,B,TC1,TC2 respectively.
+ */
+static const u8 rkl_aux_ch_map[] = {
+	[AUX_CH_A] = DP_AUX_A,
+	[AUX_CH_B] = DP_AUX_B,
+	[AUX_CH_USBC1] = DP_AUX_C,
+	[AUX_CH_USBC2] = DP_AUX_D,
+};
+
+static const u8 direct_aux_ch_map[] = {
+	[AUX_CH_A] = DP_AUX_A,
+	[AUX_CH_B] = DP_AUX_B,
+	[AUX_CH_C] = DP_AUX_C,
+	[AUX_CH_D] = DP_AUX_D, /* aka AUX_CH_USBC1 */
+	[AUX_CH_E] = DP_AUX_E, /* aka AUX_CH_USBC2 */
+	[AUX_CH_F] = DP_AUX_F, /* aka AUX_CH_USBC3 */
+	[AUX_CH_G] = DP_AUX_G, /* aka AUX_CH_USBC4 */
+	[AUX_CH_H] = DP_AUX_H, /* aka AUX_CH_USBC5 */
+	[AUX_CH_I] = DP_AUX_I, /* aka AUX_CH_USBC6 */
+};
+
 static enum aux_ch map_aux_ch(struct drm_i915_private *i915, u8 aux_channel)
 {
-	enum aux_ch aux_ch;
+	const u8 *aux_ch_map;
+	int i, n_entries;
 
-	/*
-	 * RKL/DG1 VBT uses PHY based mapping. Combo PHYs A,B,C,D
-	 * map to DDI A,B,TC1,TC2 respectively.
-	 *
-	 * ADL-S VBT uses PHY based mapping. Combo PHYs A,B,C,D,E
-	 * map to DDI A,TC1,TC2,TC3,TC4 respectively.
-	 */
-	switch (aux_channel) {
-	case DP_AUX_A:
-		aux_ch = AUX_CH_A;
-		break;
-	case DP_AUX_B:
-		if (IS_ALDERLAKE_S(i915))
-			aux_ch = AUX_CH_USBC1;
-		else
-			aux_ch = AUX_CH_B;
-		break;
-	case DP_AUX_C:
-		if (IS_ALDERLAKE_S(i915))
-			aux_ch = AUX_CH_USBC2;
-		else if (IS_DG1(i915) || IS_ROCKETLAKE(i915))
-			aux_ch = AUX_CH_USBC1;
-		else
-			aux_ch = AUX_CH_C;
-		break;
-	case DP_AUX_D:
-		if (DISPLAY_VER(i915) >= 13)
-			aux_ch = AUX_CH_D_XELPD;
-		else if (IS_ALDERLAKE_S(i915))
-			aux_ch = AUX_CH_USBC3;
-		else if (IS_DG1(i915) || IS_ROCKETLAKE(i915))
-			aux_ch = AUX_CH_USBC2;
-		else
-			aux_ch = AUX_CH_D;
-		break;
-	case DP_AUX_E:
-		if (DISPLAY_VER(i915) >= 13)
-			aux_ch = AUX_CH_E_XELPD;
-		else if (IS_ALDERLAKE_S(i915))
-			aux_ch = AUX_CH_USBC4;
-		else
-			aux_ch = AUX_CH_E;
-		break;
-	case DP_AUX_F:
-		if (DISPLAY_VER(i915) >= 13)
-			aux_ch = AUX_CH_USBC1;
-		else
-			aux_ch = AUX_CH_F;
-		break;
-	case DP_AUX_G:
-		if (DISPLAY_VER(i915) >= 13)
-			aux_ch = AUX_CH_USBC2;
-		else
-			aux_ch = AUX_CH_G;
-		break;
-	case DP_AUX_H:
-		if (DISPLAY_VER(i915) >= 13)
-			aux_ch = AUX_CH_USBC3;
-		else
-			aux_ch = AUX_CH_H;
-		break;
-	case DP_AUX_I:
-		if (DISPLAY_VER(i915) >= 13)
-			aux_ch = AUX_CH_USBC4;
-		else
-			aux_ch = AUX_CH_I;
-		break;
-	default:
-		MISSING_CASE(aux_channel);
-		aux_ch = AUX_CH_A;
-		break;
+	if (DISPLAY_VER(i915) >= 13) {
+		aux_ch_map = adlp_aux_ch_map;
+		n_entries = ARRAY_SIZE(adlp_aux_ch_map);
+	} else if (IS_ALDERLAKE_S(i915)) {
+		aux_ch_map = adls_aux_ch_map;
+		n_entries = ARRAY_SIZE(adls_aux_ch_map);
+	} else if (IS_DG1(i915) || IS_ROCKETLAKE(i915)) {
+		aux_ch_map = rkl_aux_ch_map;
+		n_entries = ARRAY_SIZE(rkl_aux_ch_map);
+	} else {
+		aux_ch_map = direct_aux_ch_map;
+		n_entries = ARRAY_SIZE(direct_aux_ch_map);
 	}
 
-	return aux_ch;
+	for (i = 0; i < n_entries; i++) {
+		if (aux_ch_map[i] == aux_channel)
+			return i;
+	}
+
+	drm_dbg_kms(&i915->drm,
+		    "Ignoring alternate AUX CH: VBT claims AUX 0x%x, which is not valid for this platform\n",
+		    aux_channel);
+
+	return AUX_CH_NONE;
 }
 
 enum aux_ch intel_bios_dp_aux_ch(const struct intel_bios_encoder_data *devdata)