perf/smmuv3: Add DT support

Add support for probing PMCGs from DT, which in itself is trivially
simple. Since DT-based systems with SMMUv3 are most likely to be using
Arm Ltd. implementations at the moment, a further treat is that DT lets
us unambiguously detect those such that we can retroactively make them
a standardised IIDR value to present as a userspace identifier.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>

drivers/perf/arm_smmuv3_pmu.c

@@ -47,6 +47,7 @@
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/msi.h>
+#include <linux/of.h>
 #include <linux/perf_event.h>
 #include <linux/platform_device.h>
 #include <linux/smp.h>
@@ -75,6 +76,10 @@
 #define SMMU_PMCG_CR                    0xE04
 #define SMMU_PMCG_CR_ENABLE             BIT(0)
 #define SMMU_PMCG_IIDR                  0xE08
+#define SMMU_PMCG_IIDR_PRODUCTID	GENMASK(31, 20)
+#define SMMU_PMCG_IIDR_VARIANT		GENMASK(19, 16)
+#define SMMU_PMCG_IIDR_REVISION		GENMASK(15, 12)
+#define SMMU_PMCG_IIDR_IMPLEMENTER	GENMASK(11, 0)
 #define SMMU_PMCG_CEID0                 0xE20
 #define SMMU_PMCG_CEID1                 0xE28
 #define SMMU_PMCG_IRQ_CTRL              0xE50
@@ -83,6 +88,20 @@
 #define SMMU_PMCG_IRQ_CFG1              0xE60
 #define SMMU_PMCG_IRQ_CFG2              0xE64
 
+/* IMP-DEF ID registers */
+#define SMMU_PMCG_PIDR0			0xFE0
+#define SMMU_PMCG_PIDR0_PART_0		GENMASK(7, 0)
+#define SMMU_PMCG_PIDR1			0xFE4
+#define SMMU_PMCG_PIDR1_DES_0		GENMASK(7, 4)
+#define SMMU_PMCG_PIDR1_PART_1		GENMASK(3, 0)
+#define SMMU_PMCG_PIDR2			0xFE8
+#define SMMU_PMCG_PIDR2_REVISION	GENMASK(7, 4)
+#define SMMU_PMCG_PIDR2_DES_1		GENMASK(2, 0)
+#define SMMU_PMCG_PIDR3			0xFEC
+#define SMMU_PMCG_PIDR3_REVAND		GENMASK(7, 4)
+#define SMMU_PMCG_PIDR4			0xFD0
+#define SMMU_PMCG_PIDR4_DES_2		GENMASK(3, 0)
+
 /* MSI config fields */
 #define MSI_CFG0_ADDR_MASK              GENMASK_ULL(51, 2)
 #define MSI_CFG2_MEMATTR_DEVICE_nGnRE   0x1
@@ -754,6 +773,40 @@ static void smmu_pmu_get_acpi_options(struct smmu_pmu *smmu_pmu)
 	dev_notice(smmu_pmu->dev, "option mask 0x%x\n", smmu_pmu->options);
 }
 
+static bool smmu_pmu_coresight_id_regs(struct smmu_pmu *smmu_pmu)
+{
+	return of_device_is_compatible(smmu_pmu->dev->of_node, "arm,mmu-600-pmcg");
+}
+
+static void smmu_pmu_get_iidr(struct smmu_pmu *smmu_pmu)
+{
+	u32 iidr = readl_relaxed(smmu_pmu->reg_base + SMMU_PMCG_IIDR);
+
+	if (!iidr && smmu_pmu_coresight_id_regs(smmu_pmu)) {
+		u32 pidr0 = readl(smmu_pmu->reg_base + SMMU_PMCG_PIDR0);
+		u32 pidr1 = readl(smmu_pmu->reg_base + SMMU_PMCG_PIDR1);
+		u32 pidr2 = readl(smmu_pmu->reg_base + SMMU_PMCG_PIDR2);
+		u32 pidr3 = readl(smmu_pmu->reg_base + SMMU_PMCG_PIDR3);
+		u32 pidr4 = readl(smmu_pmu->reg_base + SMMU_PMCG_PIDR4);
+
+		u32 productid = FIELD_GET(SMMU_PMCG_PIDR0, pidr0) |
+				(FIELD_GET(SMMU_PMCG_PIDR1_PART_1, pidr1) << 8);
+		u32 variant = FIELD_GET(SMMU_PMCG_PIDR2_REVISION, pidr2);
+		u32 revision = FIELD_GET(SMMU_PMCG_PIDR3_REVAND, pidr3);
+		u32 implementer =
+			FIELD_GET(SMMU_PMCG_PIDR1_DES_0, pidr1) |
+			(FIELD_GET(SMMU_PMCG_PIDR2_DES_1, pidr2) << 4) |
+			(FIELD_GET(SMMU_PMCG_PIDR4_DES_2, pidr4) << 8);
+
+		iidr = FIELD_PREP(SMMU_PMCG_IIDR_PRODUCTID, productid) |
+		       FIELD_PREP(SMMU_PMCG_IIDR_VARIANT, variant) |
+		       FIELD_PREP(SMMU_PMCG_IIDR_REVISION, revision) |
+		       FIELD_PREP(SMMU_PMCG_IIDR_IMPLEMENTER, implementer);
+	}
+
+	smmu_pmu->iidr = iidr;
+}
+
 static int smmu_pmu_probe(struct platform_device *pdev)
 {
 	struct smmu_pmu *smmu_pmu;
@@ -825,7 +878,7 @@ static int smmu_pmu_probe(struct platform_device *pdev)
 		return err;
 	}
 
-	smmu_pmu->iidr = readl_relaxed(smmu_pmu->reg_base + SMMU_PMCG_IIDR);
+	smmu_pmu_get_iidr(smmu_pmu);
 
 	name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "smmuv3_pmcg_%llx",
 			      (res_0->start) >> SMMU_PMCG_PA_SHIFT);
@@ -834,7 +887,8 @@ static int smmu_pmu_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	smmu_pmu_get_acpi_options(smmu_pmu);
+	if (!dev->of_node)
+		smmu_pmu_get_acpi_options(smmu_pmu);
 
 	/* Pick one CPU to be the preferred one to use */
 	smmu_pmu->on_cpu = raw_smp_processor_id();
@@ -884,9 +938,16 @@ static void smmu_pmu_shutdown(struct platform_device *pdev)
 	smmu_pmu_disable(&smmu_pmu->pmu);
 }
 
+static const struct of_device_id smmu_pmu_of_match[] = {
+	{ .compatible = "arm,smmu-v3-pmcg" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, smmu_pmu_of_match);
+
 static struct platform_driver smmu_pmu_driver = {
 	.driver = {
 		.name = "arm-smmu-v3-pmcg",
+		.of_match_table = smmu_pmu_of_match,
 		.suppress_bind_attrs = true,
 	},
 	.probe = smmu_pmu_probe,