platform/x86/amd: hfi: Add debugfs support

JIRA: https://issues.redhat.com/browse/RHEL-107081

commit 13bc67a
Author: Mario Limonciello <mario.limonciello@amd.com>
Date:   Mon Jun 9 15:05:17 2025 -0500

    platform/x86/amd: hfi: Add debugfs support

    Add a dump of the class and capabilities table to debugfs to assist
    with debugging scheduler issues.

    Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
    Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
    Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
    Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
    Link: https://lore.kernel.org/20250609200518.3616080-13-superm1@kernel.org

Signed-off-by: Steve Best <sbest@redhat.com>

Author: sfbest

drivers/platform/x86/amd/hfi/hfi.c

@@ -13,6 +13,7 @@
 #include <linux/acpi.h>
 #include <linux/cpu.h>
 #include <linux/cpumask.h>
+#include <linux/debugfs.h>
 #include <linux/gfp.h>
 #include <linux/init.h>
 #include <linux/io.h>
@@ -73,6 +74,8 @@ struct amd_hfi_data {
 	void __iomem		*pcc_comm_addr;
 	struct acpi_subtable_header	*pcct_entry;
 	struct amd_shmem_info	*shmem;
+
+	struct dentry *dbgfs_dir;
 };
 
 /**
@@ -238,6 +241,13 @@ static int amd_hfi_alloc_class_data(struct platform_device *pdev)
 	return 0;
 }
 
+static void amd_hfi_remove(struct platform_device *pdev)
+{
+	struct amd_hfi_data *dev = platform_get_drvdata(pdev);
+
+	debugfs_remove_recursive(dev->dbgfs_dir);
+}
+
 static int amd_set_hfi_ipcc_score(struct amd_hfi_cpuinfo *hfi_cpuinfo, int cpu)
 {
 	for (int i = 0; i < hfi_cpuinfo->nr_class; i++)
@@ -393,6 +403,26 @@ static int amd_hfi_metadata_parser(struct platform_device *pdev,
 	return ret;
 }
 
+static int class_capabilities_show(struct seq_file *s, void *unused)
+{
+	u32 cpu, idx;
+
+	seq_puts(s, "CPU #\tWLC\tPerf\tEff\n");
+	for_each_possible_cpu(cpu) {
+		struct amd_hfi_cpuinfo *hfi_cpuinfo = per_cpu_ptr(&amd_hfi_cpuinfo, cpu);
+
+		seq_printf(s, "%d", cpu);
+		for (idx = 0; idx < hfi_cpuinfo->nr_class; idx++) {
+			seq_printf(s, "\t%u\t%u\t%u\n", idx,
+				   hfi_cpuinfo->amd_hfi_classes[idx].perf,
+				   hfi_cpuinfo->amd_hfi_classes[idx].eff);
+		}
+	}
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(class_capabilities);
+
 static int amd_hfi_pm_resume(struct device *dev)
 {
 	int ret, cpu;
@@ -469,6 +499,10 @@ static int amd_hfi_probe(struct platform_device *pdev)
 
 	schedule_work(&sched_amd_hfi_itmt_work);
 
+	amd_hfi_data->dbgfs_dir = debugfs_create_dir("amd_hfi", arch_debugfs_dir);
+	debugfs_create_file("class_capabilities", 0644, amd_hfi_data->dbgfs_dir, pdev,
+			    &class_capabilities_fops);
+
 	return 0;
 }
 
@@ -480,6 +514,7 @@ static struct platform_driver amd_hfi_driver = {
 		.acpi_match_table = ACPI_PTR(amd_hfi_platform_match),
 	},
 	.probe = amd_hfi_probe,
+	.remove = amd_hfi_remove,
 };
 
 static int __init amd_hfi_init(void)