iommu/arm-smmu: Add support for dynamic bus scale voting
Some SMMU operations (like register access and ATOS) require downstream
buses to be enabled. We've been getting lucky for a long time since
other clients have been voting for the buses in question, but recently
we've seen some unclocked accesses due to our missing vote. Add support
for bus scale voting to the driver. The voting parameters will be
provided later in the per-target device tree SMMU configuration.
Change-Id: I6b31c887ad817a6628f4234622c73dee046d6442
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 6764dae..d6d4cb0 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -44,6 +44,8 @@
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
+#include <linux/msm-bus.h>
+#include <dt-bindings/msm/msm-bus-ids.h>
#include <linux/amba/bus.h>
@@ -402,6 +404,9 @@
struct regulator *gdsc;
+ struct msm_bus_client_handle *bus_client;
+ char *bus_client_name;
+
/* Protects power_count */
struct mutex power_lock;
int power_count;
@@ -766,6 +771,21 @@
return regulator_disable(smmu->gdsc);
}
+static int arm_smmu_request_bus(struct arm_smmu_device *smmu)
+{
+ if (!smmu->bus_client)
+ return 0;
+ return msm_bus_scale_update_bw(smmu->bus_client, 0, 1000);
+}
+
+static int arm_smmu_unrequest_bus(struct arm_smmu_device *smmu)
+{
+ if (!smmu->bus_client)
+ return 0;
+ return msm_bus_scale_update_bw(smmu->bus_client, 0, 0);
+}
+
+
static int arm_smmu_power_on_slow(struct arm_smmu_device *smmu)
{
int ret;
@@ -781,14 +801,20 @@
if (ret)
goto out_unlock;
- ret = arm_smmu_prepare_clocks(smmu);
+ ret = arm_smmu_request_bus(smmu);
if (ret)
goto out_disable_regulators;
+ ret = arm_smmu_prepare_clocks(smmu);
+ if (ret)
+ goto out_disable_bus;
+
smmu->power_count += 1;
mutex_unlock(&smmu->power_lock);
return 0;
+out_disable_bus:
+ arm_smmu_unrequest_bus(smmu);
out_disable_regulators:
arm_smmu_disable_regulators(smmu);
out_unlock:
@@ -808,6 +834,7 @@
}
arm_smmu_unprepare_clocks(smmu);
+ arm_smmu_unrequest_bus(smmu);
arm_smmu_disable_regulators(smmu);
mutex_unlock(&smmu->power_lock);
@@ -2728,6 +2755,37 @@
return 0;
}
+static int arm_smmu_init_bus_scaling(struct platform_device *pdev,
+ struct arm_smmu_device *smmu)
+{
+ u32 master_id;
+
+ if (of_property_read_u32(pdev->dev.of_node, "qcom,bus-master-id",
+ &master_id)) {
+ dev_dbg(smmu->dev, "No bus scaling info\n");
+ return 0;
+ }
+
+ smmu->bus_client_name = devm_kasprintf(
+ smmu->dev, GFP_KERNEL, "smmu-bus-client-%s",
+ dev_name(smmu->dev));
+
+ if (!smmu->bus_client_name)
+ return -ENOMEM;
+
+ smmu->bus_client = msm_bus_scale_register(
+ master_id, MSM_BUS_SLAVE_EBI_CH0, smmu->bus_client_name, true);
+ if (IS_ERR(&smmu->bus_client)) {
+ int ret = PTR_ERR(smmu->bus_client);
+
+ if (ret != -EPROBE_DEFER)
+ dev_err(smmu->dev, "Bus client registration failed\n");
+ return ret;
+ }
+
+ return 0;
+}
+
static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
{
unsigned long size;
@@ -3040,6 +3098,10 @@
if (err)
return err;
+ err = arm_smmu_init_bus_scaling(pdev, smmu);
+ if (err)
+ return err;
+
err = arm_smmu_power_on(smmu);
if (err)
return err;
@@ -3165,6 +3227,8 @@
writel(sCR0_CLIENTPD, ARM_SMMU_GR0_NS(smmu) + ARM_SMMU_GR0_sCR0);
arm_smmu_power_off(smmu);
+ msm_bus_scale_unregister(smmu->bus_client);
+
return 0;
}