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iommu/arm-smmu: allow translation stage to be forced on the cmdline

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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>
This commit is contained in:
Will Deacon 2014-07-14 19:47:39 +01:00
parent 9e82bf0141
commit 4cf740b0b6
1 changed files with 13 additions and 2 deletions
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15
drivers/iommu/arm-smmu.c
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@ -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;
}