[RFC PATCH v2 53/58] iommu/arm-smmu-v3-kvm: Probe power domains

[Mostafa Saleh <smostafa@google.com>]

From: Jean-Philippe Brucker <jean-philippe@linaro.org>

Try to use SCMI if possible, otherwise rely on HVC to the hypervisor
to notify about power changes, this is ONLY safe if the SMMU resets
to blocking DMA.

Signed-off-by: Mostafa Saleh <smostafa@google.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 .../iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c   | 78 +++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c
index 674ce2b02a4b..deeed994a131 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c
@@ -8,6 +8,7 @@
 #include <asm/kvm_mmu.h>
 
 #include <linux/arm-smccc.h>
+#include <linux/of_address.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 
@@ -21,6 +22,7 @@ struct host_arm_smmu_device {
 	struct arm_smmu_device		smmu;
 	pkvm_handle_t			id;
 	u32				boot_gbpa;
+	struct kvm_power_domain		power_domain;
 };
 
 #define smmu_to_host(_smmu) \
@@ -654,6 +656,77 @@ static int kvm_arm_smmu_device_reset(struct host_arm_smmu_device *host_smmu)
 	return 0;
 }
 
+static int kvm_arm_probe_scmi_pd(struct device_node *scmi_node,
+				 struct kvm_power_domain *pd)
+{
+	int ret;
+	struct resource res;
+	struct of_phandle_args args;
+
+	pd->type = KVM_POWER_DOMAIN_ARM_SCMI;
+
+	ret = of_parse_phandle_with_args(scmi_node, "shmem", NULL, 0, &args);
+	if (ret)
+		return ret;
+
+	ret = of_address_to_resource(args.np, 0, &res);
+	if (ret)
+		goto out_put_nodes;
+
+	ret = of_property_read_u32(scmi_node, "arm,smc-id",
+				   &pd->arm_scmi.smc_id);
+	if (ret)
+		goto out_put_nodes;
+
+	/*
+	 * The shared buffer is unmapped from the host while a request is in
+	 * flight, so it has to be on its own page.
+	 */
+	if (!IS_ALIGNED(res.start, SZ_64K) || resource_size(&res) < SZ_64K) {
+		ret = -EINVAL;
+		goto out_put_nodes;
+	}
+
+	pd->arm_scmi.shmem_base = res.start;
+	pd->arm_scmi.shmem_size = resource_size(&res);
+
+out_put_nodes:
+	of_node_put(args.np);
+	return ret;
+}
+
+/* TODO: Move this. None of it is specific to SMMU */
+static int kvm_arm_probe_power_domain(struct device *dev,
+				      struct kvm_power_domain *pd)
+{
+	int ret;
+	struct device_node *parent;
+	struct of_phandle_args args;
+
+	if (!of_get_property(dev->of_node, "power-domains", NULL))
+		return 0;
+
+	ret = of_parse_phandle_with_args(dev->of_node, "power-domains",
+					 "#power-domain-cells", 0, &args);
+	if (ret)
+		return ret;
+
+	parent = of_get_parent(args.np);
+	if (parent && of_device_is_compatible(parent, "arm,scmi-smc") &&
+	    args.args_count > 0) {
+		pd->arm_scmi.domain_id = args.args[0];
+		ret = kvm_arm_probe_scmi_pd(parent, pd);
+	} else {
+		dev_warn(dev, "Unknown PM method for %pOF, using HVC\n",
+			 args.np);
+		pd->type = KVM_POWER_DOMAIN_HOST_HVC;
+		pd->device_id = kvm_arm_smmu_cur;
+	}
+	of_node_put(parent);
+	of_node_put(args.np);
+	return ret;
+}
+
 static int kvm_arm_smmu_probe(struct platform_device *pdev)
 {
 	int ret;
@@ -681,6 +754,10 @@ static int kvm_arm_smmu_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	ret = kvm_arm_probe_power_domain(dev, &host_smmu->power_domain);
+	if (ret)
+		return ret;
+
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	size = resource_size(res);
 	if (size < SZ_128K) {
@@ -738,6 +815,7 @@ static int kvm_arm_smmu_probe(struct platform_device *pdev)
 	hyp_smmu->mmio_addr = ioaddr;
 	hyp_smmu->mmio_size = size;
 	hyp_smmu->features = smmu->features;
+	hyp_smmu->iommu.power_domain = host_smmu->power_domain;
 	kvm_arm_smmu_cur++;
 
 	return arm_smmu_register_iommu(smmu, &kvm_arm_smmu_ops, ioaddr);
-- 
2.47.0.338.g60cca15819-goog