Re: [PATCH -next] iommu/arm-smmu-v3: Add suspend and resume support
From: Robin Murphy
Date: Wed Jul 21 2021 - 07:56:08 EST
[ +Marc for MSI bits ]
On 2021-07-21 02:33, Bixuan Cui wrote:
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 <cuibixuan@xxxxxxxxxx>
Reviewed-by: Wei Yongjun <weiyongjun1@xxxxxxxxxx>
Reviewed-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
Reviewed-by: Ding Tianhong <dingtianhong@xxxxxxxxxx>
Reviewed-by: Hanjun Guo <guohanjun@xxxxxxxxxx>
---
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;
+ }
My gut feeling is that this is something a device driver maybe shouldn't
be poking into, but I'm not entirely familiar with the area :/
+
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;
What about wired IRQs?
+ }
/* 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)
Er, what about the use of "bypass" towards the end of the function. Have
you even compiled this?
{
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.
+ */
Is that guaranteed? What if suspend is only implemented by external
clock-gating?
+ 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;
Once again...
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);
...either this is based on some out-of-tree hack which introduced its
own uninitialised-usage bug here, or it doesn't even compile.
+ 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,
Either use SET_SYSTEM_SLEEP_PM_OPS() here or drop the __maybe_unused
annmotations above - they're pointless if the callbacks are referenced
unconditionally.
Robin.
+};
+
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,