Re: [PATCH v16 1/5] iommu/arm-smmu: Add pm_runtime/sleep ops

[Vivek Gautam]

On Wed, Sep 26, 2018 at 8:57 PM Robin Murphy <robin.murphy@xxxxxxx> wrote:
>
> On 30/08/18 15:45, Vivek Gautam wrote:
> > From: Sricharan R <sricharan@xxxxxxxxxxxxxx>
> >
> > The smmu needs to be functional only when the respective
> > master's using it are active. The device_link feature
> > helps to track such functional dependencies, so that the
> > iommu gets powered when the master device enables itself
> > using pm_runtime. So by adapting the smmu driver for
> > runtime pm, above said dependency can be addressed.
> >
> > This patch adds the pm runtime/sleep callbacks to the
> > driver and also the functions to parse the smmu clocks
> > from DT and enable them in resume/suspend.
> >
> > Also, while we enable the runtime pm add a pm sleep suspend
> > callback that pushes devices to low power state by turning
> > the clocks off in a system sleep.
> > Also add corresponding clock enable path in resume callback.
> >
> > Signed-off-by: Sricharan R <sricharan@xxxxxxxxxxxxxx>
> > Signed-off-by: Archit Taneja <architt@xxxxxxxxxxxxxx>
> > [vivek: rework for clock and pm ops]
> > Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
> > Reviewed-by: Tomasz Figa <tfiga@xxxxxxxxxxxx>
> > Tested-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
> > ---
> >   drivers/iommu/arm-smmu.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++--
> >   1 file changed, 74 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> > index fd1b80ef9490..d900e007c3c9 100644
> > --- a/drivers/iommu/arm-smmu.c
> > +++ b/drivers/iommu/arm-smmu.c
> > @@ -48,6 +48,7 @@
> >   #include <linux/of_iommu.h>
> >   #include <linux/pci.h>
> >   #include <linux/platform_device.h>
> > +#include <linux/pm_runtime.h>
> >   #include <linux/slab.h>
> >   #include <linux/spinlock.h>
> >
> > @@ -205,6 +206,8 @@ struct arm_smmu_device {
> >       u32                             num_global_irqs;
> >       u32                             num_context_irqs;
> >       unsigned int                    *irqs;
> > +     struct clk_bulk_data            *clks;
> > +     int                             num_clks;
> >
> >       u32                             cavium_id_base; /* Specific to Cavium */
> >
> > @@ -1896,10 +1899,12 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
> >   struct arm_smmu_match_data {
> >       enum arm_smmu_arch_version version;
> >       enum arm_smmu_implementation model;
> > +     const char * const *clks;
> > +     int num_clks;
> >   };
> >
> >   #define ARM_SMMU_MATCH_DATA(name, ver, imp) \
> > -static struct arm_smmu_match_data name = { .version = ver, .model = imp }
> > +static const struct arm_smmu_match_data name = { .version = ver, .model = imp }
> >
> >   ARM_SMMU_MATCH_DATA(smmu_generic_v1, ARM_SMMU_V1, GENERIC_SMMU);
> >   ARM_SMMU_MATCH_DATA(smmu_generic_v2, ARM_SMMU_V2, GENERIC_SMMU);
> > @@ -1918,6 +1923,23 @@ static const struct of_device_id arm_smmu_of_match[] = {
> >   };
> >   MODULE_DEVICE_TABLE(of, arm_smmu_of_match);
> >
> > +static void arm_smmu_fill_clk_data(struct arm_smmu_device *smmu,
> > +                                const char * const *clks)
> > +{
> > +     int i;
> > +
> > +     if (smmu->num_clks < 1)
> > +             return;
> > +
> > +     smmu->clks = devm_kcalloc(smmu->dev, smmu->num_clks,
> > +                               sizeof(*smmu->clks), GFP_KERNEL);
> > +     if (!smmu->clks)
> > +             return;
> > +
> > +     for (i = 0; i < smmu->num_clks; i++)
> > +             smmu->clks[i].id = clks[i];
> > +}
> > +
> >   #ifdef CONFIG_ACPI
> >   static int acpi_smmu_get_data(u32 model, struct arm_smmu_device *smmu)
> >   {
> > @@ -2000,6 +2022,9 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev,
> >       data = of_device_get_match_data(dev);
> >       smmu->version = data->version;
> >       smmu->model = data->model;
> > +     smmu->num_clks = data->num_clks;
> > +
> > +     arm_smmu_fill_clk_data(smmu, data->clks);
> >
> >       parse_driver_options(smmu);
> >
> > @@ -2098,6 +2123,14 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
> >               smmu->irqs[i] = irq;
> >       }
> >
> > +     err = devm_clk_bulk_get(smmu->dev, smmu->num_clks, smmu->clks);
> > +     if (err)
> > +             return err;
> > +
> > +     err = clk_bulk_prepare_enable(smmu->num_clks, smmu->clks);
> > +     if (err)
> > +             return err;
> > +
>
> Hmm, if we error out beyond here it looks like we should strictly
> balance that prepare/enable before devres does the clk_bulk_put(),
> however the probe error path is starting to look like it needs a bit of
> love in general, so I might just spin a cleanup patch on top (and even
> then only for the sake of not being a bad example; SMMU probe failure is
> never a realistic situation for the system to actually recover from).

Sure Robin. Thanks for the review on the series.
Let me know, I can spin a change for probe failure path cleanup.

Best regards
Vivek

>
> Otherwise,
>
> Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
>
> >       err = arm_smmu_device_cfg_probe(smmu);
> >       if (err)
> >               return err;
> > @@ -2184,6 +2217,9 @@ static int arm_smmu_device_remove(struct platform_device *pdev)
> >
> >       /* Turn the thing off */
> >       writel(sCR0_CLIENTPD, ARM_SMMU_GR0_NS(smmu) + ARM_SMMU_GR0_sCR0);
> > +
> > +     clk_bulk_disable_unprepare(smmu->num_clks, smmu->clks);
> > +
> >       return 0;
> >   }
> >
> > @@ -2192,15 +2228,50 @@ static void arm_smmu_device_shutdown(struct platform_device *pdev)
> >       arm_smmu_device_remove(pdev);
> >   }
> >
> > -static int __maybe_unused arm_smmu_pm_resume(struct device *dev)
> > +static int __maybe_unused arm_smmu_runtime_resume(struct device *dev)
> >   {
> >       struct arm_smmu_device *smmu = dev_get_drvdata(dev);
> > +     int ret;
> > +
> > +     ret = clk_bulk_enable(smmu->num_clks, smmu->clks);
> > +     if (ret)
> > +             return ret;
> >
> >       arm_smmu_device_reset(smmu);
> > +
> >       return 0;
> >   }
> >
> > -static SIMPLE_DEV_PM_OPS(arm_smmu_pm_ops, NULL, arm_smmu_pm_resume);
> > +static int __maybe_unused arm_smmu_runtime_suspend(struct device *dev)
> > +{
> > +     struct arm_smmu_device *smmu = dev_get_drvdata(dev);
> > +
> > +     clk_bulk_disable(smmu->num_clks, smmu->clks);
> > +
> > +     return 0;
> > +}
> > +
> > +static int __maybe_unused arm_smmu_pm_resume(struct device *dev)
> > +{
> > +     if (pm_runtime_suspended(dev))
> > +             return 0;
> > +
> > +     return arm_smmu_runtime_resume(dev);
> > +}
> > +
> > +static int __maybe_unused arm_smmu_pm_suspend(struct device *dev)
> > +{
> > +     if (pm_runtime_suspended(dev))
> > +             return 0;
> > +
> > +     return arm_smmu_runtime_suspend(dev);
> > +}
> > +
> > +static const struct dev_pm_ops arm_smmu_pm_ops = {
> > +     SET_SYSTEM_SLEEP_PM_OPS(arm_smmu_pm_suspend, arm_smmu_pm_resume)
> > +     SET_RUNTIME_PM_OPS(arm_smmu_runtime_suspend,
> > +                        arm_smmu_runtime_resume, NULL)
> > +};
> >
> >   static struct platform_driver arm_smmu_driver = {
> >       .driver = {
> >
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