Re: [PATCH v3 0/8] iommu/arm-smmu: Support maintaining bootloader mappings

[Laurentiu Tudor]

On 9/4/2020 6:55 PM, Bjorn Andersson wrote:
> Based on previous attempts and discussions this is the latest attempt at
> inheriting stream mappings set up by the bootloader, for e.g. boot splash or
> efifb.
> 
> Per Will's request this builds on the work by Jordan and Rob for the Adreno
> SMMU support. It applies cleanly ontop of v16 of their series, which can be
> found at
> https://lore.kernel.org/linux-arm-msm/20200901164707.2645413-1-robdclark@xxxxxxxxx/
> 
> Bjorn Andersson (8):
>   iommu/arm-smmu: Refactor context bank allocation
>   iommu/arm-smmu: Delay modifying domain during init
>   iommu/arm-smmu: Consult context bank allocator for identify domains
>   iommu/arm-smmu-qcom: Emulate bypass by using context banks
>   iommu/arm-smmu-qcom: Consistently initialize stream mappings
>   iommu/arm-smmu: Add impl hook for inherit boot mappings
>   iommu/arm-smmu: Provide helper for allocating identity domain
>   iommu/arm-smmu-qcom: Setup identity domain for boot mappings
> 
>  drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 111 ++++++++++++++++++-
>  drivers/iommu/arm/arm-smmu/arm-smmu.c      | 122 ++++++++++++++-------
>  drivers/iommu/arm/arm-smmu/arm-smmu.h      |  14 ++-
>  3 files changed, 205 insertions(+), 42 deletions(-)
> 

Tested on a NXP LX2160A with John's tree [1] and below diff [2], so for
the whole series:

Tested-by: Laurentiu Tudor <laurentiu.tudor@xxxxxxx>

[1]
https://git.linaro.org/people/john.stultz/android-dev.git/log/?h=dev/db845c-mainline-WIP
[2]
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c
@@ -190,11 +190,43 @@ static const struct arm_smmu_impl mrvl_mmu500_impl = {
        .reset = arm_mmu500_reset,
 };

+static int nxp_smmu_inherit_mappings(struct arm_smmu_device *smmu)
+{
+       u32 smr;
+       int i, cnt = 0;
+
+       for (i = 0; i < smmu->num_mapping_groups; i++) {
+               smr = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_SMR(i));
+
+               if (FIELD_GET(ARM_SMMU_SMR_VALID, smr)) {
+                       smmu->smrs[i].id = FIELD_GET(ARM_SMMU_SMR_ID, smr);
+                       smmu->smrs[i].mask =
FIELD_GET(ARM_SMMU_SMR_MASK, smr);
+                       smmu->smrs[i].valid = true;
+
+                       smmu->s2crs[i].type = S2CR_TYPE_BYPASS;
+                       smmu->s2crs[i].privcfg = S2CR_PRIVCFG_DEFAULT;
+                       smmu->s2crs[i].count++;
+
+                       cnt++;
+               }
+       }
+
+       dev_notice(smmu->dev, "\tpreserved %d boot mapping%s\n", cnt,
+                  cnt == 1 ? "" : "s");
+
+       return 0;
+}
+
+static const struct arm_smmu_impl nxp_impl = {
+       .inherit_mappings = nxp_smmu_inherit_mappings,
+};

 struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu)
 {
        const struct device_node *np = smmu->dev->of_node;

        /*
         * Set the impl for model-specific implementation quirks first,
         * such that platform integration quirks can pick it up and
@@ -229,5 +261,12 @@ struct arm_smmu_device *arm_smmu_impl_init(struct
arm_smmu_device *smmu)
        if (of_device_is_compatible(np, "marvell,ap806-smmu-500"))
                smmu->impl = &mrvl_mmu500_impl;

+       if (of_property_read_bool(np, "nxp,keep-bypass-mappings"))
+               smmu->impl = &nxp_impl;

---
Best Regards, Laurentiu