Re: [PATCH v6 2/6] iommu/arm-smmu: Add pm_runtime/sleep ops

[Vivek Gautam <vivek.gautam@codeaurora.org>]

On 1/31/2018 5:53 PM, Robin Murphy wrote:
> On 19/01/18 11:43, Vivek Gautam wrote:
>> From: Sricharan R <sricharan@codeaurora.org>
>>
>> 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.
>>
>> Signed-off-by: Sricharan R <sricharan@codeaurora.org>
>> Signed-off-by: Archit Taneja <architt@codeaurora.org>
>> [vivek: Clock rework to request bulk of clocks]
>> Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
>> ---
>>   drivers/iommu/arm-smmu.c | 55 
>> ++++++++++++++++++++++++++++++++++++++++++++++--
>>   1 file changed, 53 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
>> index 78d4c6b8f1ba..21acffe91a1c 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 +206,9 @@ struct arm_smmu_device {
>>       u32                num_global_irqs;
>>       u32                num_context_irqs;
>>       unsigned int            *irqs;
>> +    struct clk_bulk_data        *clocks;
>> +    int                num_clks;
>> +    const char * const        *clk_names;
>
> This seems unnecessary, as we use it a grand total of of once, during 
> initialisation when we have the source data directly to hand. Just 
> pass data->clks into arm_smmu_init_clks() as an additional argument.

Sure, will do that.
>
> Otherwise, I think this looks reasonable; it's about as unobtrusive as 
> it's going to get.

Thanks for reviewing.

regards
Vivek

>
> Robin.
>
>>       u32                cavium_id_base; /* Specific to Cavium */
>>   @@ -1685,6 +1689,25 @@ static int arm_smmu_id_size_to_bits(int size)
>>       }
>>   }
>>   +static int arm_smmu_init_clocks(struct arm_smmu_device *smmu)
>> +{
>> +    int i;
>> +    int num = smmu->num_clks;
>> +
>> +    if (num < 1)
>> +        return 0;
>> +
>> +    smmu->clocks = devm_kcalloc(smmu->dev, num,
>> +                    sizeof(*smmu->clocks), GFP_KERNEL);
>> +    if (!smmu->clocks)
>> +        return -ENOMEM;
>> +
>> +    for (i = 0; i < num; i++)
>> +        smmu->clocks[i].id = smmu->clk_names[i];
>> +
>> +    return devm_clk_bulk_get(smmu->dev, num, smmu->clocks);
>> +}
>> +
>>   static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
>>   {
>>       unsigned long size;
>> @@ -1897,10 +1920,12 @@ 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);
>> @@ -2001,6 +2026,8 @@ 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->clk_names = data->clks;
>> +    smmu->num_clks = data->num_clks;
>>         parse_driver_options(smmu);
>>   @@ -2099,6 +2126,10 @@ static int arm_smmu_device_probe(struct 
>> platform_device *pdev)
>>           smmu->irqs[i] = irq;
>>       }
>>   +    err = arm_smmu_init_clocks(smmu);
>> +    if (err)
>> +        return err;
>> +
>>       err = arm_smmu_device_cfg_probe(smmu);
>>       if (err)
>>           return err;
>> @@ -2197,7 +2228,27 @@ static int __maybe_unused 
>> arm_smmu_pm_resume(struct device *dev)
>>       return 0;
>>   }
>>   -static SIMPLE_DEV_PM_OPS(arm_smmu_pm_ops, NULL, arm_smmu_pm_resume);
>> +static int __maybe_unused arm_smmu_runtime_resume(struct device *dev)
>> +{
>> +    struct arm_smmu_device *smmu = dev_get_drvdata(dev);
>> +
>> +    return clk_bulk_prepare_enable(smmu->num_clks, smmu->clocks);
>> +}
>> +
>> +static int __maybe_unused arm_smmu_runtime_suspend(struct device *dev)
>> +{
>> +    struct arm_smmu_device *smmu = dev_get_drvdata(dev);
>> +
>> +    clk_bulk_disable_unprepare(smmu->num_clks, smmu->clocks);
>> +
>> +    return 0;
>> +}
>> +
>> +static const struct dev_pm_ops arm_smmu_pm_ops = {
>> +    SET_SYSTEM_SLEEP_PM_OPS(NULL, 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    = {
>>