[PATCH v4] perf: arm_dsu: Support DSU ACPI devices

[Tuan Phan]

Add support for probing device from ACPI node.
Each DSU ACPI node and its associated cpus are inside a cluster node.

Signed-off-by: Tuan Phan <tuanphan at os.amperecomputing.com>
---
Changes in v4:
- Addressed Will's comments.

Changes in v3:
- Based on the latest ARM ACPI binding at: https://developer.arm.com/documentation/den0093/c/

Changes in v2:
- Removed IRQF_SHARED.
- Fixed ACPI runtime detection.

 drivers/perf/arm_dsu_pmu.c | 59 +++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 53 insertions(+), 6 deletions(-)

diff --git a/drivers/perf/arm_dsu_pmu.c b/drivers/perf/arm_dsu_pmu.c
index 96ed93c..92c9c9d 100644
--- a/drivers/perf/arm_dsu_pmu.c
+++ b/drivers/perf/arm_dsu_pmu.c
@@ -11,6 +11,7 @@
 #define DRVNAME		PMUNAME "_pmu"
 #define pr_fmt(fmt)	DRVNAME ": " fmt
 
+#include <linux/acpi.h>
 #include <linux/bitmap.h>
 #include <linux/bitops.h>
 #include <linux/bug.h>
@@ -603,18 +604,19 @@ static struct dsu_pmu *dsu_pmu_alloc(struct platform_device *pdev)
 }
 
 /**
- * dsu_pmu_dt_get_cpus: Get the list of CPUs in the cluster.
+ * dsu_pmu_dt_get_cpus: Get the list of CPUs in the cluster
+ * from device tree.
  */
-static int dsu_pmu_dt_get_cpus(struct device_node *dev, cpumask_t *mask)
+static int dsu_pmu_dt_get_cpus(struct device *dev, cpumask_t *mask)
 {
 	int i = 0, n, cpu;
 	struct device_node *cpu_node;
 
-	n = of_count_phandle_with_args(dev, "cpus", NULL);
+	n = of_count_phandle_with_args(dev->of_node, "cpus", NULL);
 	if (n <= 0)
 		return -ENODEV;
 	for (; i < n; i++) {
-		cpu_node = of_parse_phandle(dev, "cpus", i);
+		cpu_node = of_parse_phandle(dev->of_node, "cpus", i);
 		if (!cpu_node)
 			break;
 		cpu = of_cpu_node_to_id(cpu_node);
@@ -631,6 +633,34 @@ static int dsu_pmu_dt_get_cpus(struct device_node *dev, cpumask_t *mask)
 	return 0;
 }
 
+/**
+ * dsu_pmu_acpi_get_cpus: Get the list of CPUs in the cluster
+ * from ACPI.
+ */
+static int dsu_pmu_acpi_get_cpus(struct device *dev, cpumask_t *mask)
+{
+	int cpu;
+
+	/*
+	 * A dsu pmu node is inside a cluster parent node along with cpu nodes.
+	 * We need to find out all cpus that have the same parent with this pmu.
+	 */
+	for_each_possible_cpu(cpu) {
+		struct acpi_device *acpi_dev;
+		struct device *cpu_dev = get_cpu_device(cpu);
+
+		if (!cpu_dev)
+			continue;
+
+		acpi_dev = ACPI_COMPANION(cpu_dev);
+		if (acpi_dev &&
+			acpi_dev->parent == ACPI_COMPANION(dev)->parent)
+			cpumask_set_cpu(cpu, mask);
+	}
+
+	return 0;
+}
+
 /*
  * dsu_pmu_probe_pmu: Probe the PMU details on a CPU in the cluster.
  */
@@ -676,6 +706,7 @@ static int dsu_pmu_device_probe(struct platform_device *pdev)
 {
 	int irq, rc;
 	struct dsu_pmu *dsu_pmu;
+	struct fwnode_handle *fwnode = dev_fwnode(&pdev->dev);
 	char *name;
 	static atomic_t pmu_idx = ATOMIC_INIT(-1);
 
@@ -683,7 +714,16 @@ static int dsu_pmu_device_probe(struct platform_device *pdev)
 	if (IS_ERR(dsu_pmu))
 		return PTR_ERR(dsu_pmu);
 
-	rc = dsu_pmu_dt_get_cpus(pdev->dev.of_node, &dsu_pmu->associated_cpus);
+	if (IS_ERR_OR_NULL(fwnode))
+		return -ENOENT;
+
+	if (is_of_node(fwnode))
+		rc = dsu_pmu_dt_get_cpus(&pdev->dev, &dsu_pmu->associated_cpus);
+	else if (is_acpi_device_node(fwnode))
+		rc = dsu_pmu_acpi_get_cpus(&pdev->dev, &dsu_pmu->associated_cpus);
+	else
+		return -ENOENT;
+
 	if (rc) {
 		dev_warn(&pdev->dev, "Failed to parse the CPUs\n");
 		return rc;
@@ -752,11 +792,19 @@ static const struct of_device_id dsu_pmu_of_match[] = {
 	{ .compatible = "arm,dsu-pmu", },
 	{},
 };
+MODULE_DEVICE_TABLE(of, dsu_pmu_of_match);
+
+static const struct acpi_device_id dsu_pmu_acpi_match[] = {
+	{ "ARMHD500", 0},
+	{},
+};
+MODULE_DEVICE_TABLE(acpi, dsu_pmu_acpi_match);
 
 static struct platform_driver dsu_pmu_driver = {
 	.driver = {
 		.name	= DRVNAME,
 		.of_match_table = of_match_ptr(dsu_pmu_of_match),
+		.acpi_match_table = ACPI_PTR(dsu_pmu_acpi_match),
 		.suppress_bind_attrs = true,
 	},
 	.probe = dsu_pmu_device_probe,
@@ -826,7 +874,6 @@ static void __exit dsu_pmu_exit(void)
 module_init(dsu_pmu_init);
 module_exit(dsu_pmu_exit);
 
-MODULE_DEVICE_TABLE(of, dsu_pmu_of_match);
 MODULE_DESCRIPTION("Perf driver for ARM DynamIQ Shared Unit");
 MODULE_AUTHOR("Suzuki K Poulose <suzuki.poulose at arm.com>");
 MODULE_LICENSE("GPL v2");
-- 
2.7.4