drm/radeon/kms: add support for ss overrides on Fusion APUs

System specific spread spectrum overrides can be specified in
the integrated system info table for Fusion APUs.  This adds
support for using those overrides.
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_atombios.c

@@ -1321,6 +1321,43 @@ bool radeon_atombios_get_ppll_ss_info(struct radeon_device *rdev,
 	return false;
 }
 
+static void radeon_atombios_get_igp_ss_overrides(struct radeon_device *rdev,
+						 struct radeon_atom_ss *ss,
+						 int id)
+{
+	struct radeon_mode_info *mode_info = &rdev->mode_info;
+	int index = GetIndexIntoMasterTable(DATA, IntegratedSystemInfo);
+	u16 data_offset, size;
+	struct _ATOM_INTEGRATED_SYSTEM_INFO_V6 *igp_info;
+	u8 frev, crev;
+	u16 percentage = 0, rate = 0;
+
+	/* get any igp specific overrides */
+	if (atom_parse_data_header(mode_info->atom_context, index, &size,
+				   &frev, &crev, &data_offset)) {
+		igp_info = (struct _ATOM_INTEGRATED_SYSTEM_INFO_V6 *)
+			(mode_info->atom_context->bios + data_offset);
+		switch (id) {
+		case ASIC_INTERNAL_SS_ON_TMDS:
+			percentage = le16_to_cpu(igp_info->usDVISSPercentage);
+			rate = le16_to_cpu(igp_info->usDVISSpreadRateIn10Hz);
+			break;
+		case ASIC_INTERNAL_SS_ON_HDMI:
+			percentage = le16_to_cpu(igp_info->usHDMISSPercentage);
+			rate = le16_to_cpu(igp_info->usHDMISSpreadRateIn10Hz);
+			break;
+		case ASIC_INTERNAL_SS_ON_LVDS:
+			percentage = le16_to_cpu(igp_info->usLvdsSSPercentage);
+			rate = le16_to_cpu(igp_info->usLvdsSSpreadRateIn10Hz);
+			break;
+		}
+		if (percentage)
+			ss->percentage = percentage;
+		if (rate)
+			ss->rate = rate;
+	}
+}
+
 union asic_ss_info {
 	struct _ATOM_ASIC_INTERNAL_SS_INFO info;
 	struct _ATOM_ASIC_INTERNAL_SS_INFO_V2 info_2;
@@ -1385,6 +1422,8 @@ bool radeon_atombios_get_asic_ss_info(struct radeon_device *rdev,
 						le16_to_cpu(ss_info->info_3.asSpreadSpectrum[i].usSpreadSpectrumPercentage);
 					ss->type = ss_info->info_3.asSpreadSpectrum[i].ucSpreadSpectrumMode;
 					ss->rate = le16_to_cpu(ss_info->info_3.asSpreadSpectrum[i].usSpreadRateIn10Hz);
+					if (rdev->flags & RADEON_IS_IGP)
+						radeon_atombios_get_igp_ss_overrides(rdev, ss, id);
 					return true;
 				}
 			}