Re: [PATCHv2 2/6] iommu/arm-smmu: Allow client devices to select direct mapping

Robin Murphy
2020-04-20T15:58:07Z

On 2020-04-20 3:37 pm, Sai Prakash Ranjan wrote:
> From: Jordan Crouse <jcrouse@codeaurora.org>
>
> Some client devices want to directly map the IOMMU themselves instead
> of using the DMA domain. Allow those devices to opt in to direct
> mapping by way of a list of compatible strings.
>
> Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
> Co-developed-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
> ---
> drivers/iommu/arm-smmu-qcom.c | 19 +++++++++++++++++++
> drivers/iommu/arm-smmu.h | 1 +
> 2 files changed, 20 insertions(+)
>
> diff --git a/drivers/iommu/arm-smmu-qcom.c b/drivers/iommu/arm-smmu-qcom.c
> index 64a4ab270ab7..0b3f159065aa 100644
> --- a/drivers/iommu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm-smmu-qcom.c
> @@ -3,6 +3,7 @@
> * Copyright (c) 2019, The Linux Foundation. All rights reserved.
> */
>
> +#include <linux/of_device.h>
> #include <linux/qcom_scm.h>
>
> #include "arm-smmu.h"
> @@ -11,6 +12,23 @@ struct qcom_smmu {
> struct arm_smmu_device smmu;
> };
>
> +static const struct of_device_id qcom_smmu_client_of_match[] = {
> + { .compatible = "qcom,adreno" },
> + { .compatible = "qcom,mdp4" },
> + { .compatible = "qcom,mdss" },
> + { .compatible = "qcom,sc7180-mdss" },
> + { .compatible = "qcom,sdm845-mdss" },
> + { }
> +};
> +
> +static int qcom_smmu_request_domain(struct device *dev)
> +{
> + const struct of_device_id *match =
> + of_match_device(qcom_smmu_client_of_match, dev);
> +
> + return match ? IOMMU_DOMAIN_IDENTITY : 0;
> +}
> +
> static int qcom_sdm845_smmu500_reset(struct arm_smmu_device *smmu)
> {
> int ret;
> @@ -41,6 +59,7 @@ static int qcom_smmu500_reset(struct arm_smmu_device *smmu)
> }
>
> static const struct arm_smmu_impl qcom_smmu_impl = {
> + .req_domain = qcom_smmu_request_domain,
> .reset = qcom_smmu500_reset,
> };
>
> diff --git a/drivers/iommu/arm-smmu.h b/drivers/iommu/arm-smmu.h
> index 8d1cd54d82a6..662fdb4dccd2 100644
> --- a/drivers/iommu/arm-smmu.h
> +++ b/drivers/iommu/arm-smmu.h
> @@ -386,6 +386,7 @@ struct arm_smmu_impl {
> int (*init_context)(struct arm_smmu_domain *smmu_domain);
> void (*tlb_sync)(struct arm_smmu_device *smmu, int page, int sync,
> int status);
> + int (*req_domain)(struct device *dev);

Nit: since the point is to implement the full iommu_ops::def_domain_type
interface, can we call it def_domain_type please?

Robin.

> };
>
> static inline void __iomem *arm_smmu_page(struct arm_smmu_device *smmu, int n)
>