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authorWill Deacon <will.deacon@arm.com>2014-07-14 22:47:39 +0400
committerWill Deacon <will.deacon@arm.com>2014-09-16 22:13:48 +0400
commit4cf740b0b6628bda1e5c9201ae0d4f56fc6c06a5 (patch)
treeccd54c982e334efced7eb7888149683d106da18e /drivers/iommu/arm-smmu.c
parent9e82bf014195d6f0054982c463575cdce24292be (diff)
downloadlinux-4cf740b0b6628bda1e5c9201ae0d4f56fc6c06a5.tar.xz
iommu/arm-smmu: allow translation stage to be forced on the cmdline
When debugging and testing code on an SMMU that supports nested translation, it can be useful to restrict the driver to a particular stage of translation. This patch adds a module parameter to the ARM SMMU driver to allow this by restricting the ability of the probe() code to detect support for only the specified stage. Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'drivers/iommu/arm-smmu.c')
-rw-r--r--drivers/iommu/arm-smmu.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index a83cc2a2a2ca..958ae8194afe 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -326,6 +326,11 @@
#define FSYNR0_WNR (1 << 4)
+static int force_stage;
+module_param_named(force_stage, force_stage, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(force_stage,
+ "Force SMMU mappings to be installed at a particular stage of translation. A value of '1' or '2' forces the corresponding stage. All other values are ignored (i.e. no stage is forced). Note that selecting a specific stage will disable support for nested translation.");
+
struct arm_smmu_smr {
u8 idx;
u16 mask;
@@ -1716,6 +1721,13 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
return -ENODEV;
}
#endif
+
+ /* Restrict available stages based on module parameter */
+ if (force_stage == 1)
+ id &= ~(ID0_S2TS | ID0_NTS);
+ else if (force_stage == 2)
+ id &= ~(ID0_S1TS | ID0_NTS);
+
if (id & ID0_S1TS) {
smmu->features |= ARM_SMMU_FEAT_TRANS_S1;
dev_notice(smmu->dev, "\tstage 1 translation\n");
@@ -1732,8 +1744,7 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
}
if (!(smmu->features &
- (ARM_SMMU_FEAT_TRANS_S1 | ARM_SMMU_FEAT_TRANS_S2 |
- ARM_SMMU_FEAT_TRANS_NESTED))) {
+ (ARM_SMMU_FEAT_TRANS_S1 | ARM_SMMU_FEAT_TRANS_S2))) {
dev_err(smmu->dev, "\tno translation support!\n");
return -ENODEV;
}