iommu/arm-smmu-v3: Add struct arm_smmu_impl_ops

Mimicing the arm-smmu (v2) driver, introduce a struct arm_smmu_impl_ops to
accommodate impl routines.

Suggested-by: Will Deacon <will@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Link: https://lore.kernel.org/r/8fe9f3805568aabf771fc6706c116459016bf62d.1724970714.git.nicolinc@nvidia.com
Signed-off-by: Will Deacon <will@kernel.org>

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -348,7 +348,12 @@ static int arm_smmu_cmdq_build_cmd(u64 *cmd, struct arm_smmu_cmdq_ent *ent)
 
 static struct arm_smmu_cmdq *arm_smmu_get_cmdq(struct arm_smmu_device *smmu)
 {
-	return &smmu->cmdq;
+	struct arm_smmu_cmdq *cmdq = NULL;
+
+	if (smmu->impl_ops && smmu->impl_ops->get_secondary_cmdq)
+		cmdq = smmu->impl_ops->get_secondary_cmdq(smmu);
+
+	return cmdq ?: &smmu->cmdq;
 }
 
 static bool arm_smmu_cmdq_needs_busy_polling(struct arm_smmu_device *smmu,
@@ -4052,6 +4057,14 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu)
 		return ret;
 	}
 
+	if (smmu->impl_ops && smmu->impl_ops->device_reset) {
+		ret = smmu->impl_ops->device_reset(smmu);
+		if (ret) {
+			dev_err(smmu->dev, "failed to reset impl\n");
+			return ret;
+		}
+	}
+
 	return 0;
 }
 
@@ -4466,6 +4479,38 @@ static void arm_smmu_rmr_install_bypass_ste(struct arm_smmu_device *smmu)
 	iort_put_rmr_sids(dev_fwnode(smmu->dev), &rmr_list);
 }
 
+static void arm_smmu_impl_remove(void *data)
+{
+	struct arm_smmu_device *smmu = data;
+
+	if (smmu->impl_ops && smmu->impl_ops->device_remove)
+		smmu->impl_ops->device_remove(smmu);
+}
+
+/*
+ * Probe all the compiled in implementations. Each one checks to see if it
+ * matches this HW and if so returns a devm_krealloc'd arm_smmu_device which
+ * replaces the callers. Otherwise the original is returned or ERR_PTR.
+ */
+static struct arm_smmu_device *arm_smmu_impl_probe(struct arm_smmu_device *smmu)
+{
+	struct arm_smmu_device *new_smmu = ERR_PTR(-ENODEV);
+	int ret;
+
+	/* Add impl probe */
+
+	if (new_smmu == ERR_PTR(-ENODEV))
+		return smmu;
+	if (IS_ERR(new_smmu))
+		return new_smmu;
+
+	ret = devm_add_action_or_reset(new_smmu->dev, arm_smmu_impl_remove,
+				       new_smmu);
+	if (ret)
+		return ERR_PTR(ret);
+	return new_smmu;
+}
+
 static int arm_smmu_device_probe(struct platform_device *pdev)
 {
 	int irq, ret;
@@ -4487,6 +4532,10 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	smmu = arm_smmu_impl_probe(smmu);
+	if (IS_ERR(smmu))
+		return PTR_ERR(smmu);
+
 	/* Base address */
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res)

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h

@@ -14,6 +14,8 @@
 #include <linux/mmzone.h>
 #include <linux/sizes.h>
 
+struct arm_smmu_device;
+
 /* MMIO registers */
 #define ARM_SMMU_IDR0			0x0
 #define IDR0_ST_LVL			GENMASK(28, 27)
@@ -630,9 +632,17 @@ struct arm_smmu_strtab_cfg {
 	u32				strtab_base_cfg;
 };
 
+struct arm_smmu_impl_ops {
+	int (*device_reset)(struct arm_smmu_device *smmu);
+	void (*device_remove)(struct arm_smmu_device *smmu);
+	struct arm_smmu_cmdq *(*get_secondary_cmdq)(struct arm_smmu_device *smmu);
+};
+
 /* An SMMUv3 instance */
 struct arm_smmu_device {
 	struct device			*dev;
+	const struct arm_smmu_impl_ops	*impl_ops;
+
 	void __iomem			*base;
 	void __iomem			*page1;