iommu: apple-dart: Support combinations of locked and unlocked DARTs

This is required for the display sub-system. m1n1 locks the DART of the
boot framebuffer to minimize the blackout for the transition from boot
framebuffer to the full display driver. The display blacks out when the
bootloader setup mapping of the framebuffer vanishes during
dart_reset(). Under certain circumstances this results in an
unrecoverable crash of display coprocessor.

Signed-off-by: Janne Grunau <j@jannau.net>

Author: jannau

drivers/iommu/apple-dart.c

@@ -294,6 +294,7 @@ struct apple_dart_domain {
 struct apple_dart_master_cfg {
 	/* Intersection of DART capabilitles */
 	u32 supports_bypass : 1;
+	u32 locked : 1;
 
 	struct apple_dart_stream_map stream_maps[MAX_DARTS_PER_DEVICE];
 };
@@ -991,6 +992,8 @@ static int apple_dart_of_xlate(struct device *dev,
 			return -ENOMEM;
 		/* Will be ANDed with DART capabilities */
 		cfg->supports_bypass = true;
+		/* Will be ORed with DART capabilities*/
+		cfg->locked = false;
 	}
 	dev_iommu_priv_set(dev, cfg);
 
@@ -1001,6 +1004,7 @@ static int apple_dart_of_xlate(struct device *dev,
 	}
 
 	cfg->supports_bypass &= dart->supports_bypass;
+	cfg->locked |= dart->locked;
 
 	for (i = 0; i < MAX_DARTS_PER_DEVICE; ++i) {
 		if (cfg->stream_maps[i].dart == dart) {