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

Sricharan R <sricharan@xxxxxxxxxxxxxx> · Mon, 20 Mar 2017 20:18:05 +0530

Hi Rob,

On 3/17/2017 2:33 AM, Rob Herring wrote:
On Thu, Mar 09, 2017 at 09:05:45PM +0530, Sricharan R 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@xxxxxxxxxxxxxx>
---
 .../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

_clk is redundant

ok, will remove it.


+                  "arm,mmu-400", "arm,mmu-401" and "arm,mmu-500"
+
+                  "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 generally shouldn't be optional. Either the h/w has a clock or it
doesn't.


ok, will not define it as 'optional'. I will define it to be soc
specific. Also will change the driver to ignore the clk not present,
just to reuse/have common clock enable functions for MMU-500
for other socs as well. Only problem being unable to catch a case
where a clk DT entry is not populated when it should have been.

Regards,
 Sricharan

+
+- 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);

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