Re: [PATCH -next] iommu/arm-smmu-v3: Add suspend and resume support

Add suspend and resume support for arm-smmu-v3 by low-power mode.

When the smmu is suspended, it is powered off and the registers are
cleared. So saves the msi_msg context during msi interrupt initialization
of smmu. When resume happens it calls arm_smmu_device_reset() to restore
the registers.

Signed-off-by: Bixuan Cui <redacted>
Reviewed-by: Wei Yongjun <redacted>
Reviewed-by: Zhen Lei <redacted>
Reviewed-by: Ding Tianhong <redacted>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
---

  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 72 ++++++++++++++++++---
  1 file changed, 64 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 235f9bdaeaf2..bf1163acbcb1 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -40,6 +40,7 @@ MODULE_PARM_DESC(disable_bypass,
  
  static bool disable_msipolling;
  module_param(disable_msipolling, bool, 0444);
+static bool bypass;
  MODULE_PARM_DESC(disable_msipolling,
  	"Disable MSI-based polling for CMD_SYNC completion.");
  

@@ -3129,11 +3130,37 @@ static void arm_smmu_write_msi_msg(struct msi_desc *desc, struct msi_msg *msg)
  	doorbell = (((u64)msg->address_hi) << 32) | msg->address_lo;
  	doorbell &= MSI_CFG0_ADDR_MASK;
  
+	/* Saves the msg context for resume if desc->msg is empty */
+	if (desc->msg.address_lo == 0 && desc->msg.address_hi == 0) {
+		desc->msg.address_lo = msg->address_lo;
+		desc->msg.address_hi = msg->address_hi;
+		desc->msg.data = msg->data;
+	}

+
  	writeq_relaxed(doorbell, smmu->base + cfg[0]);
  	writel_relaxed(msg->data, smmu->base + cfg[1]);
  	writel_relaxed(ARM_SMMU_MEMATTR_DEVICE_nGnRE, smmu->base + cfg[2]);
  }
  
+static void arm_smmu_resume_msis(struct arm_smmu_device *smmu)
+{
+	struct msi_desc *desc;
+	struct device *dev = smmu->dev;
+
+	for_each_msi_entry(desc, dev) {
+		switch (desc->platform.msi_index) {
+		case EVTQ_MSI_INDEX:
+		case GERROR_MSI_INDEX:
+		case PRIQ_MSI_INDEX:
+			arm_smmu_write_msi_msg(desc, &(desc->msg));
+			break;
+		default:
+			continue;
+
+		}
+	}
+}
+
  static void arm_smmu_setup_msis(struct arm_smmu_device *smmu)
  {
  	struct msi_desc *desc;

@@ -3184,11 +3211,17 @@ static void arm_smmu_setup_msis(struct arm_smmu_device *smmu)
  	devm_add_action(dev, arm_smmu_free_msis, dev);
  }
  
-static void arm_smmu_setup_unique_irqs(struct arm_smmu_device *smmu)
+static void arm_smmu_setup_unique_irqs(struct arm_smmu_device *smmu, bool resume_mode)
  {
  	int irq, ret;
  
-	arm_smmu_setup_msis(smmu);
+	if (!resume_mode)
+		arm_smmu_setup_msis(smmu);
+	else {
+		/* The irq doesn't need to be re-requested during resume */
+		arm_smmu_resume_msis(smmu);
+		return;

+	}
  
  	/* Request interrupt lines */
  	irq = smmu->evtq.q.irq;

@@ -3230,7 +3263,7 @@ static void arm_smmu_setup_unique_irqs(struct arm_smmu_device *smmu)
  	}
  }
  
-static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu)
+static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu, bool resume_mode)
  {
  	int ret, irq;
  	u32 irqen_flags = IRQ_CTRL_EVTQ_IRQEN | IRQ_CTRL_GERROR_IRQEN;

@@ -3257,7 +3290,7 @@ static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu)
  		if (ret < 0)
  			dev_warn(smmu->dev, "failed to enable combined irq\n");
  	} else
-		arm_smmu_setup_unique_irqs(smmu);
+		arm_smmu_setup_unique_irqs(smmu, resume_mode);
  
  	if (smmu->features & ARM_SMMU_FEAT_PRI)
  		irqen_flags |= IRQ_CTRL_PRIQ_IRQEN;

@@ -3282,7 +3315,7 @@ static int arm_smmu_device_disable(struct arm_smmu_device *smmu)
  	return ret;
  }
  
-static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
+static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool resume_mode)

  {
  	int ret;
  	u32 reg, enables;

@@ -3392,7 +3425,7 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
  		}
  	}
  
-	ret = arm_smmu_setup_irqs(smmu);
+	ret = arm_smmu_setup_irqs(smmu, resume_mode);
  	if (ret) {
  		dev_err(smmu->dev, "failed to setup irqs\n");
  		return ret;

@@ -3749,6 +3782,24 @@ static void __iomem *arm_smmu_ioremap(struct device *dev, resource_size_t start,
  	return devm_ioremap_resource(dev, &res);
  }
  
+static int __maybe_unused arm_smmu_suspend(struct device *dev)
+{
+	/*
+	 * The smmu is powered off and related registers are automatically
+	 * cleared when suspend. No need to do anything.
+	 */

+	return 0;
+}
+
+static int __maybe_unused arm_smmu_resume(struct device *dev)
+{
+	struct arm_smmu_device *smmu = dev_get_drvdata(dev);
+
+	arm_smmu_device_reset(smmu, true);
+
+	return 0;
+}
+
  static int arm_smmu_device_probe(struct platform_device *pdev)
  {
  	int irq, ret;

@@ -3756,7 +3807,6 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
  	resource_size_t ioaddr;
  	struct arm_smmu_device *smmu;
  	struct device *dev = &pdev->dev;
-	bool bypass;

  	smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL);
  	if (!smmu)

@@ -3831,7 +3881,7 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
  	platform_set_drvdata(pdev, smmu);
  
  	/* Reset the device */
-	ret = arm_smmu_device_reset(smmu, bypass);

+	ret = arm_smmu_device_reset(smmu, false);
  	if (ret)
  		return ret;
  

@@ -3884,6 +3934,11 @@ static const struct of_device_id arm_smmu_of_match[] = {
  };
  MODULE_DEVICE_TABLE(of, arm_smmu_of_match);
  
+static const struct dev_pm_ops arm_smmu_pm_ops = {
+	.suspend = arm_smmu_suspend,
+	.resume = arm_smmu_resume,

+};
+
  static void arm_smmu_driver_unregister(struct platform_driver *drv)
  {
  	arm_smmu_sva_notifier_synchronize();

@@ -3895,6 +3950,7 @@ static struct platform_driver arm_smmu_driver = {
  		.name			= "arm-smmu-v3",
  		.of_match_table		= arm_smmu_of_match,
  		.suppress_bind_attrs	= true,
+		.pm			= &arm_smmu_pm_ops,
  	},
  	.probe	= arm_smmu_device_probe,
  	.remove	= arm_smmu_device_remove,