[PATCH 2/2] iommu: apple-dart: Allow mismatched bypass support

Sasha Finkelstein via B4 Relay
2025-02-27T16:56:08Z

From: Hector Martin <marcan@marcan.st>

This is needed by ISP, which has DART0 with bypass and DART1/2 without.

Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
---
drivers/iommu/apple-dart.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index edb2fb22333506d7c64ad1b6321df00ebfd07747..a41ad0627be003f2b0ce42a128c3b04bb2537d56 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -277,6 +277,9 @@ struct apple_dart_domain {
* @streams: streams for this device
*/
struct apple_dart_master_cfg {
+ /* Intersection of DART capabilitles */
+ u32 supports_bypass : 1;
+
struct apple_dart_stream_map stream_maps[MAX_DARTS_PER_DEVICE];
};

@@ -684,7 +687,7 @@ static int apple_dart_attach_dev_identity(struct iommu_domain *domain,
struct apple_dart_stream_map *stream_map;
int i;

- if (!cfg->stream_maps[0].dart->supports_bypass)
+ if (!cfg->supports_bypass)
return -EINVAL;

for_each_stream_map(i, cfg, stream_map)
@@ -792,20 +795,25 @@ static int apple_dart_of_xlate(struct device *dev,
return -EINVAL;
sid = args->args[0];

- if (!cfg)
+ if (!cfg) {
cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
+
+ /* Will be ANDed with DART capabilities */
+ cfg->supports_bypass = true;
+ }
if (!cfg)
return -ENOMEM;
dev_iommu_priv_set(dev, cfg);

cfg_dart = cfg->stream_maps[0].dart;
if (cfg_dart) {
- if (cfg_dart->supports_bypass != dart->supports_bypass)
- return -EINVAL;
if (cfg_dart->pgsize != dart->pgsize)
return -EINVAL;
}

+ if (!dart->supports_bypass)
+ cfg->supports_bypass = false;
+
for (i = 0; i < MAX_DARTS_PER_DEVICE; ++i) {
if (cfg->stream_maps[i].dart == dart) {
set_bit(sid, cfg->stream_maps[i].sidmap);
@@ -945,7 +953,7 @@ static int apple_dart_def_domain_type(struct device *dev)

if (cfg->stream_maps[0].dart->pgsize > PAGE_SIZE)
return IOMMU_DOMAIN_IDENTITY;
- if (!cfg->stream_maps[0].dart->supports_bypass)
+ if (!cfg->supports_bypass)
return IOMMU_DOMAIN_DMA;

return 0;

--
2.48.1