Re: [PATCH] memory: Add NVIDIA SMMU suspend/resume support

[Alexandre Courbot]

Hi Mark,

On Mon, Dec 8, 2014 at 3:20 PM, Mark Zhang <markz@xxxxxxxxxx> wrote:
> This patch adds suspend/resume support for NVIDIA SMMU.


> This patch is created on top of Thierry Reding's patch set:
>
> "[PATCH v7 00/12] NVIDIA Tegra memory controller and IOMMU support"

You should have this comment under the "---" as we don't need it to
persist once this patch is merged.

>
> Signed-off-by: Mark Zhang <markz@xxxxxxxxxx>
> ---
>  drivers/iommu/tegra-smmu.c | 79 +++++++++++++++++++++++++++++++++++++++++++++-
>  drivers/memory/tegra/mc.c  | 21 ++++++++++++
>  drivers/memory/tegra/mc.h  |  4 +++
>  3 files changed, 103 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
> index 0909e0bae9ec..ab38805055a4 100644
> --- a/drivers/iommu/tegra-smmu.c
> +++ b/drivers/iommu/tegra-smmu.c
> @@ -17,6 +17,8 @@
>  #include <soc/tegra/ahb.h>
>  #include <soc/tegra/mc.h>
>
> +struct tegra_smmu_as;
> +
>  struct tegra_smmu {
>         void __iomem *regs;
>         struct device *dev;
> @@ -25,9 +27,10 @@ struct tegra_smmu {
>         const struct tegra_smmu_soc *soc;
>
>         unsigned long *asids;
> +       struct tegra_smmu_as **as;
>         struct mutex lock;
>
> -       struct list_head list;
> +       struct list_head swgroup_asid_list;
>  };
>
>  struct tegra_smmu_as {
> @@ -40,6 +43,12 @@ struct tegra_smmu_as {
>         u32 attr;
>  };
>
> +struct tegra_smmu_swgroup_asid {
> +       struct list_head list;
> +       unsigned swgroup_id;
> +       unsigned asid;
> +};
> +
>  static inline void smmu_writel(struct tegra_smmu *smmu, u32 value,
>                                unsigned long offset)
>  {
> @@ -376,6 +385,7 @@ static int tegra_smmu_as_prepare(struct tegra_smmu *smmu,
>         as->smmu = smmu;
>         as->use_count++;
>
> +       smmu->as[as->id] = as;
>         return 0;
>  }
>
> @@ -386,6 +396,7 @@ static void tegra_smmu_as_unprepare(struct tegra_smmu *smmu,
>                 return;
>
>         tegra_smmu_free_asid(smmu, as->id);
> +       smmu->as[as->id] = NULL;
>         as->smmu = NULL;
>  }
>
> @@ -398,6 +409,7 @@ static int tegra_smmu_attach_dev(struct iommu_domain *domain,
>         struct of_phandle_args args;
>         unsigned int index = 0;
>         int err = 0;
> +       struct tegra_smmu_swgroup_asid *sa = NULL;

This initialization is unneeded. Actually this declaration would
probably be better placed in the while() loop below since its usage is
local to it.

>
>         while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
>                                            &args)) {
> @@ -411,6 +423,14 @@ static int tegra_smmu_attach_dev(struct iommu_domain *domain,
>                         return err;
>
>                 tegra_smmu_enable(smmu, swgroup, as->id);
> +
> +               sa = kzalloc(sizeof(struct tegra_smmu_swgroup_asid),
> +                               GFP_KERNEL);
> +               INIT_LIST_HEAD(&sa->list);

You don't need to call INIT_LIST_HEAD on this, list_add_tail() will
effectively overwrite any initialization done by this macro (see
include/linux/list.h).

> +               sa->swgroup_id = swgroup;
> +               sa->asid = as->id;
> +               list_add_tail(&sa->list, &smmu->swgroup_asid_list);
> +
>                 index++;
>         }
>
> @@ -427,6 +447,7 @@ static void tegra_smmu_detach_dev(struct iommu_domain *domain, struct device *de
>         struct tegra_smmu *smmu = as->smmu;
>         struct of_phandle_args args;
>         unsigned int index = 0;
> +       struct tegra_smmu_swgroup_asid *sa = NULL;

Same here, move the declaration into the while() loop and remove the
initialization.

>
>         while (of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
>                                           &args)) {
> @@ -435,6 +456,13 @@ static void tegra_smmu_detach_dev(struct iommu_domain *domain, struct device *de
>                 if (args.np != smmu->dev->of_node)
>                         continue;
>
> +               list_for_each_entry(sa, &smmu->swgroup_asid_list, list) {
> +                       if (sa->asid == as->id && sa->swgroup_id == swgroup)
> +                               break;
> +               }
> +               list_del(&sa->list);
> +               kfree(sa);
> +
>                 tegra_smmu_disable(smmu, swgroup, as->id);
>                 tegra_smmu_as_unprepare(smmu, as);
>                 index++;
> @@ -651,6 +679,48 @@ static void tegra_smmu_ahb_enable(void)
>         }
>  }
>
> +void tegra_smmu_resume(struct tegra_smmu *smmu)
> +{
> +       struct tegra_smmu_as *as = NULL;
> +       unsigned int bit;
> +       u32 value;
> +       struct tegra_smmu_swgroup_asid *sa = NULL;

Again no need to initialize to NULL here.

> +
> +       for_each_set_bit(bit, smmu->asids, smmu->soc->num_asids) {
> +               as = smmu->as[bit];
> +               smmu->soc->ops->flush_dcache(as->pd, 0, SMMU_SIZE_PD);
> +
> +               smmu_writel(smmu, as->id & 0x7f, SMMU_PTB_ASID);
> +               value = SMMU_PTB_DATA_VALUE(as->pd, as->attr);
> +               smmu_writel(smmu, value, SMMU_PTB_DATA);
> +       }
> +
> +       list_for_each_entry(sa, &smmu->swgroup_asid_list, list)
> +               tegra_smmu_enable(smmu, sa->swgroup_id, sa->asid);

Actually I wonder if you could not do completely without the list
here. How about the following:

1) add a "unsigned swgroup_id" member to tegra_smmu_as, set it in
tegra_smmu_attach_dev() instead of sa->asid
2) in the "for_each_bit" loop above, call tegra_smmu_enable(smmu,
as->swgroup_id, as->id) after the last smmu_writel()

Would that work? It would allow you to get rid of the
tegra_smmu_swgroup_asid struct as well as a few memory allocations. I
don't know if that kind of 1:1 matching between as and and swgroup
makes sense for the SMMU though, maybe Thierry or Hiroshi can confirm?
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