On Fri, 09 Aug 2013 00:45:17 +0200, Tomasz Figa wrote:
> Hi KyongHo,
>
> On Thursday 08 of August 2013 18:39:05 Cho KyongHo wrote:
> > This patch gates clocks of master H/W as well as clocks of System MMU
> > if master clocks are specified.
> >
> > Some Exynos SoCs (i.e. GScalers in Exynos5250) have dependencies in
> > the gating clocks of master H/W and its System MMU. If a H/W is the
> > case, accessing control registers of System MMU is prohibited unless
> > both of the gating clocks of System MMU and its master H/W.
> >
> > Signed-off-by: Cho KyongHo <pullip.cho@xxxxxxxxxxx>
> > ---
> > drivers/iommu/exynos-iommu.c | 38
> > ++++++++++++++++++++++++++++++++++---- 1 files changed, 34
> > insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> > index 0ee73e8..005a7ed 100644
> > --- a/drivers/iommu/exynos-iommu.c
> > +++ b/drivers/iommu/exynos-iommu.c
> > @@ -173,6 +173,7 @@ struct sysmmu_drvdata {
> > struct device *dev; /* Owner of system MMU */
> > int nsfrs;
> > struct clk *clk;
> > + struct clk *clk_master;
> > int activations;
> > rwlock_t lock;
> > struct iommu_domain *domain;
> > @@ -263,6 +264,8 @@ void exynos_sysmmu_set_prefbuf(struct device *dev,
> > if (!is_sysmmu_active(data))
> > goto finish;
> >
> > + clk_enable(data->clk_master);
> > +
> > for (i = 0; i < data->nsfrs; i++) {
> > if ((readl(data->sfrbases[i] + REG_MMU_VERSION) >> 28) ==
> 3) {
> > if (!sysmmu_block(data->sfrbases[i]))
> > @@ -288,6 +291,8 @@ void exynos_sysmmu_set_prefbuf(struct device *dev,
> > sysmmu_unblock(data->sfrbases[i]);
> > }
> > }
> > +
> > + clk_disable(data->clk_master);
> > finish:
> > read_unlock_irqrestore(&data->lock, flags);
> > }
> > @@ -358,6 +363,8 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void
> > *dev_id) break;
> > }
> >
> > + clk_enable(data->clk_master);
> > +
> > if (i == pdev->num_resources) {
> > itype = SYSMMU_FAULT_UNKNOWN;
> > } else {
> > @@ -391,6 +398,8 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void
> > *dev_id) if (itype != SYSMMU_FAULT_UNKNOWN)
> > sysmmu_unblock(data->sfrbases[i]);
> >
> > + clk_disable(data->clk_master);
> > +
> > read_unlock(&data->lock);
> >
> > return IRQ_HANDLED;
> > @@ -407,11 +416,14 @@ static bool __exynos_sysmmu_disable(struct
> > sysmmu_drvdata *data) if (!set_sysmmu_inactive(data))
> > goto finish;
> >
> > + clk_enable(data->clk_master);
> > +
> > for (i = 0; i < data->nsfrs; i++)
> > __raw_writel(CTRL_DISABLE, data->sfrbases[i] +
> REG_MMU_CTRL);
> >
> > - if (data->clk)
> > - clk_disable(data->clk);
> > + clk_disable(data->clk_master);
> > +
> > + clk_disable(data->clk);
> >
> > disabled = true;
> > data->pgtable = 0;
> > @@ -454,11 +466,12 @@ static int __exynos_sysmmu_enable(struct
> > sysmmu_drvdata *data, goto finish;
> > }
> >
> > - if (data->clk)
> > - clk_enable(data->clk);
> > + clk_enable(data->clk);
> >
> > data->pgtable = pgtable;
> >
> > + clk_enable(data->clk_master);
> > +
> > for (i = 0; i < data->nsfrs; i++) {
> > __sysmmu_set_ptbase(data->sfrbases[i], pgtable);
> >
> > @@ -473,6 +486,8 @@ static int __exynos_sysmmu_enable(struct
> > sysmmu_drvdata *data, __raw_writel(CTRL_ENABLE, data->sfrbases[i] +
> > REG_MMU_CTRL); }
> >
> > + clk_disable(data->clk_master);
> > +
> > data->domain = domain;
> >
> > dev_dbg(data->sysmmu, "Enabled\n");
> > @@ -528,6 +543,7 @@ static void sysmmu_tlb_invalidate_entry(struct
> > device *dev, unsigned long iova)
> >
> > if (is_sysmmu_active(data)) {
> > int i;
> > + clk_enable(data->clk_master);
> > for (i = 0; i < data->nsfrs; i++) {
> > if (sysmmu_block(data->sfrbases[i])) {
> > __sysmmu_tlb_invalidate_entry(
> > @@ -535,6 +551,7 @@ static void sysmmu_tlb_invalidate_entry(struct
> > device *dev, unsigned long iova) sysmmu_unblock(data->sfrbases[i]);
> > }
> > }
> > + clk_disable(data->clk_master);
> > } else {
> > dev_dbg(data->sysmmu, "Disabled. Skipping invalidating
> TLB.\n");
> > }
> > @@ -551,12 +568,14 @@ void exynos_sysmmu_tlb_invalidate(struct device
> > *dev)
> >
> > if (is_sysmmu_active(data)) {
> > int i;
> > + clk_enable(data->clk_master);
> > for (i = 0; i < data->nsfrs; i++) {
> > if (sysmmu_block(data->sfrbases[i])) {
> > __sysmmu_tlb_invalidate(data-
> >sfrbases[i]);
> > sysmmu_unblock(data->sfrbases[i]);
> > }
> > }
> > + clk_disable(data->clk_master);
> > } else {
> > dev_dbg(data->sysmmu, "Disabled. Skipping invalidating
> TLB.\n");
> > }
> > @@ -637,6 +656,17 @@ static int __init exynos_sysmmu_probe(struct
> > platform_device *pdev) return ret;
> > }
> >
> > + data->clk_master = devm_clk_get(dev, "master");
> > + if (IS_ERR(data->clk_master))
> > + data->clk_master = NULL;
> > +
> > + ret = clk_prepare(data->clk_master);
> > + if (ret) {
> > + clk_unprepare(data->clk);
> > + dev_err(dev, "Failed to prepare master's clk\n");
> > + return ret;
> > + }
> > +
> > rwlock_init(&data->lock);
> > INIT_LIST_HEAD(&data->node);
>
> This should be done in a more appropriate way, but at the moment the PM
> Core doesn't have any provision to implement any sane solution for this
> kind of problems, so this is fine.
>
I think it is just a work-around of H/W restriction that System MMU
can be accessed and work if the both clocks of System MMU and master IP
are ungated.
Exynos4210/4412 does not have the restriction.
Some H/W in Exynos5250, Exynos5420 have the restriction.
> Reviewed-by: Tomasz Figa <t.figa@xxxxxxxxxxx>
Thanks.
>
> Best regards,
> Tomasz
>
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