Commit 4cf740b0 authored by Will Deacon's avatar Will Deacon
Browse files

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: default avatarWill Deacon <will.deacon@arm.com>
parent 9e82bf01

drivers/iommu/arm-smmu.c

+13 −2
Original line number Diff line number Diff line
@@ -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;

	}

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