Re: [PATCH V3 2/5] iommu/arm-smmu: Add support for MMU40x/500 clocks

[Sricharan R <sricharan-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>]

Hi,

On 3/17/2017 4:22 AM, Rob Clark wrote:
> On Thu, Mar 9, 2017 at 10:35 AM, Sricharan R <sricharan-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> wrote:
>> The MMU400x/500 is the implementation of the SMMUv2
>> arch specification. It is split in to two blocks
>> TBU, TCU. TBU caches the page table, instantiated
>> for each master locally, clocked by the TBUn_clk.
>> TCU manages the address translation with PTW and has
>> the programming interface as well, clocked using the
>> TCU_CLK. The TBU can also be sharing the same clock
>> domain as TCU, in which case both are clocked using
>> the TCU_CLK.
>>
>> This defines the clock bindings for the same and adds the
>> init, enable and disable functions for handling the
>> clocks.
>>
>> Signed-off-by: Sricharan R <sricharan-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
>> ---
>>  .../devicetree/bindings/iommu/arm,smmu.txt         | 27 ++++++
>>  drivers/iommu/arm-smmu.c                           | 95 +++++++++++++++++++++-
>>  2 files changed, 121 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> index 6cdf32d..b369c13 100644
>> --- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> @@ -60,6 +60,28 @@ conditions.
>>                    aliases of secure registers have to be used during
>>                    SMMU configuration.
>>
>> +- clock-names:    Should be "tbu_clk" and "tcu_clk" and "cfg_clk" for
>> +                  "arm,mmu-400", "arm,mmu-401" and "arm,mmu-500"
>
> I guess that should be: "Should be "tbu_clk" *or* "tcu_clk" and
> "cfg_clk" for..."
>
> Also, possibly we should define our own compat strings for various
> SoC's that require these clks so we can properly describe when they
> are required?  I guess that would address Rob H's comment.
>

Ok, calling "optional" does not look correct. But i was trying to define
something which would be right for all implementations of MMU-500, but
looks like that's not the right way. Making it soc specific would give a
exact description, except for the number of compatibles and have to
change the code to not consider any of tbu , tcu, cfg clk as mandatory
for adding support for other compatibles later which are mostly similar.
So i am trying to setup the clocks using functions specific for each
compatible. Not sure, if at this point, some soc specific callback from 
the driver where these things can be initialized might be good.

Regards,
  Sricharan



Regards,
  Sricharan

> BR,
> -R
>
>> +                  "tcu_clk" is required for smmu's register access using the
>> +                  programming interface and ptw for downstream bus access.
>> +
>> +                  "tbu_clk" is required for access to the TBU connected to the
>> +                  master locally. This clock is optional and not required when
>> +                  TBU is in the same clock domain as the TCU or when the TBU is
>> +                  clocked along with the master.
>> +
>> +                  "cfg_clk" is optional if required to access the TCU's programming
>> +                  interface, apart from the "tcu_clk".
>> +
>> +- clocks:         Phandles for respective clocks described by clock-names.
>> +
>> +- power-domains:  Phandles to SMMU's power domain specifier. This is
>> +                  required even if SMMU belongs to the master's power
>> +                  domain, as the SMMU will have to be enabled and
>> +                  accessed before master gets enabled and linked to its
>> +                  SMMU.
>> +
>>  ** Deprecated properties:
>>
>>  - mmu-masters (deprecated in favour of the generic "iommus" binding) :
>> @@ -84,6 +106,11 @@ conditions.
>>                               <0 36 4>,
>>                               <0 37 4>;
>>                  #iommu-cells = <1>;
>> +                clocks = <&gcc GCC_SMMU_CFG_CLK>,
>> +                         <&gcc GCC_APSS_TCU_CLK>,
>> +                        <&gcc GCC_MDP_TBU_CLK>;
>> +
>> +               clock-names = "cfg_clk", "tcu_clk", "tbu_clk";
>>          };
>>
>>          /* device with two stream IDs, 0 and 7 */
>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
>> index f7e11d3..720a1ef 100644
>> --- a/drivers/iommu/arm-smmu.c
>> +++ b/drivers/iommu/arm-smmu.c
>> @@ -341,6 +341,12 @@ struct arm_smmu_master_cfg {
>>  #define for_each_cfg_sme(fw, i, idx) \
>>         for (i = 0; idx = fwspec_smendx(fw, i), i < fw->num_ids; ++i)
>>
>> +struct mmu500_clk {
>> +       struct clk *cfg_clk;
>> +       struct clk *tcu_clk;
>> +       struct clk *tbu_clk;
>> +};
>> +
>>  struct arm_smmu_clks {
>>         void *clks;
>>         int (*init_clocks)(struct arm_smmu_device *smmu);
>> @@ -455,6 +461,92 @@ static struct arm_smmu_domain *to_smmu_domain(struct iommu_domain *dom)
>>         return container_of(dom, struct arm_smmu_domain, domain);
>>  }
>>
>> +static int mmu500_enable_clocks(struct arm_smmu_device *smmu)
>> +{
>> +       int ret = 0;
>> +       struct mmu500_clk *sclks = smmu->smmu_clks.clks;
>> +
>> +       if (!sclks)
>> +               return 0;
>> +
>> +       ret = clk_prepare_enable(sclks->cfg_clk);
>> +       if (ret) {
>> +               dev_err(smmu->dev, "Couldn't enable cfg_clk");
>> +               return ret;
>> +       }
>> +
>> +       ret = clk_prepare_enable(sclks->tcu_clk);
>> +       if (ret) {
>> +               dev_err(smmu->dev, "Couldn't enable tcu_clk");
>> +               clk_disable_unprepare(sclks->cfg_clk);
>> +               return ret;
>> +       }
>> +
>> +       ret = clk_prepare_enable(sclks->tbu_clk);
>> +       if (ret) {
>> +               dev_err(smmu->dev, "Couln't enable tbu_clk");
>> +               clk_disable_unprepare(sclks->tcu_clk);
>> +               clk_disable_unprepare(sclks->cfg_clk);
>> +               return ret;
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>> +static void mmu500_disable_clocks(struct arm_smmu_device *smmu)
>> +{
>> +       struct mmu500_clk *sclks = smmu->smmu_clks.clks;
>> +
>> +       if (!sclks) {
>> +               clk_disable_unprepare(sclks->tbu_clk);
>> +               clk_disable_unprepare(sclks->tcu_clk);
>> +               clk_disable_unprepare(sclks->cfg_clk);
>> +       }
>> +}
>> +
>> +static int mmu500_init_clocks(struct arm_smmu_device *smmu)
>> +{
>> +       struct device *dev = smmu->dev;
>> +       struct mmu500_clk *sclks;
>> +       int err;
>> +
>> +       if (!of_find_property(dev->of_node, "clocks", NULL))
>> +               return 0;
>> +
>> +       sclks = devm_kzalloc(dev, sizeof(*sclks), GFP_KERNEL);
>> +       if (!sclks)
>> +               return -ENOMEM;
>> +
>> +       sclks->cfg_clk = devm_clk_get(dev, "cfg_clk");
>> +       if (IS_ERR(sclks->cfg_clk)) {
>> +               err = PTR_ERR(sclks->cfg_clk);
>> +               /* Ignore all, except -EPROBE_DEFER for optional clocks */
>> +               if (err == -EPROBE_DEFER)
>> +                       return err;
>> +               else
>> +                       sclks->cfg_clk = NULL;
>> +       }
>> +
>> +       sclks->tcu_clk = devm_clk_get(dev, "tcu_clk");
>> +       if (IS_ERR(sclks->tcu_clk)) {
>> +               dev_err(dev, "Couldn't get tcu_clk");
>> +               return PTR_ERR(sclks->tcu_clk);
>> +       }
>> +
>> +       sclks->tbu_clk = devm_clk_get(dev, "tbu_clk");
>> +       if (IS_ERR(sclks->tbu_clk)) {
>> +               err = PTR_ERR(sclks->tbu_clk);
>> +               /* Ignore all, ecept -EPROBE_DEFER for optional clocks */
>> +               if (err == -EPROBE_DEFER)
>> +                       return err;
>> +               else
>> +                       sclks->tbu_clk = NULL;
>> +       }
>> +
>> +       smmu->smmu_clks.clks = sclks;
>> +       return 0;
>> +}
>> +
>>  static void parse_driver_options(struct arm_smmu_device *smmu)
>>  {
>>         int i = 0;
>> @@ -1981,7 +2073,8 @@ struct arm_smmu_match_data {
>>                     NULL, NULL, NULL);
>>  ARM_SMMU_MATCH_DATA(arm_mmu401, ARM_SMMU_V1_64K, GENERIC_SMMU,
>>                     NULL, NULL, NULL);
>> -ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500, NULL, NULL, NULL);
>> +ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500, mmu500_init_clocks,
>> +                   mmu500_enable_clocks, mmu500_disable_clocks);
>>  ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2,
>>                     NULL, NULL, NULL);
>>
>> --
>> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
>>
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