linux-kernel - [PATCH 5/5] iommu/dart: Assert !locked when configuring

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Message-Id: <20250210-locked-dart-v1-5-5d97fe247f35@rosenzweig.io>
Date: Mon, 10 Feb 2025 14:39:57 -0500
From: Alyssa Rosenzweig <alyssa@...enzweig.io>
To: Sven Peter <sven@...npeter.dev>, Janne Grunau <j@...nau.net>, 
 Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>, 
 Robin Murphy <robin.murphy@....com>
Cc: asahi@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
 iommu@...ts.linux.dev, linux-kernel@...r.kernel.org, 
 Alyssa Rosenzweig <alyssa@...enzweig.io>
Subject: [PATCH 5/5] iommu/dart: Assert !locked when configuring

Configuration is only possible and needed for non-locked DARTs and will
fail for locked DARTs. We cannot try -- assert that we do not.

Signed-off-by: Alyssa Rosenzweig <alyssa@...enzweig.io>
---
 drivers/iommu/apple-dart.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index 29b627b38e8c37afd2b6a72865f43d24b633834a..87eb87bb2f5158d000a2c2fc801b722a2262c941 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -309,6 +309,7 @@ apple_dart_hw_enable_translation(struct apple_dart_stream_map *stream_map)
 	struct apple_dart *dart = stream_map->dart;
 	int sid;
 
+	WARN_ON(stream_map->dart->locked);
 	for_each_set_bit(sid, stream_map->sidmap, dart->num_streams)
 		writel(dart->hw->tcr_enabled, dart->regs + DART_TCR(dart, sid));
 }
@@ -318,6 +319,7 @@ static void apple_dart_hw_disable_dma(struct apple_dart_stream_map *stream_map)
 	struct apple_dart *dart = stream_map->dart;
 	int sid;
 
+	WARN_ON(stream_map->dart->locked);
 	for_each_set_bit(sid, stream_map->sidmap, dart->num_streams)
 		writel(dart->hw->tcr_disabled, dart->regs + DART_TCR(dart, sid));
 }
@@ -328,7 +330,7 @@ apple_dart_hw_enable_bypass(struct apple_dart_stream_map *stream_map)
 	struct apple_dart *dart = stream_map->dart;
 	int sid;
 
-	WARN_ON(!stream_map->dart->supports_bypass);
+	WARN_ON(stream_map->dart->locked || !stream_map->dart->supports_bypass);
 	for_each_set_bit(sid, stream_map->sidmap, dart->num_streams)
 		writel(dart->hw->tcr_bypass,
 		       dart->regs + DART_TCR(dart, sid));
@@ -340,6 +342,7 @@ static void apple_dart_hw_set_ttbr(struct apple_dart_stream_map *stream_map,
 	struct apple_dart *dart = stream_map->dart;
 	int sid;
 
+	WARN_ON(stream_map->dart->locked);
 	WARN_ON(paddr & ((1 << dart->hw->ttbr_shift) - 1));
 	for_each_set_bit(sid, stream_map->sidmap, dart->num_streams)
 		writel(dart->hw->ttbr_valid |
@@ -353,6 +356,7 @@ static void apple_dart_hw_clear_ttbr(struct apple_dart_stream_map *stream_map,
 	struct apple_dart *dart = stream_map->dart;
 	int sid;
 
+	WARN_ON(stream_map->dart->locked);
 	for_each_set_bit(sid, stream_map->sidmap, dart->num_streams)
 		writel(0, dart->regs + DART_TTBR(dart, sid, idx));
 }

-- 
2.48.1