1 files changed, 120 insertions, 0 deletions
diff --git a/drivers/acpi/processor_pdc.c b/drivers/acpi/processor_pdc.c
new file mode 100644
index 0000000000..994091bd52
--- /dev/null
+++ b/drivers/acpi/processor_pdc.c
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2005 Intel Corporation
+ * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
+ *
+ *      Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
+ *      - Added _PDC for platforms with Intel CPUs
+ */
+
+#define pr_fmt(fmt) "ACPI: " fmt
+
+#include <linux/slab.h>
+#include <linux/acpi.h>
+#include <acpi/processor.h>
+
+#include "internal.h"
+
+static void acpi_set_pdc_bits(u32 *buf)
+{
+	buf[0] = ACPI_PDC_REVISION_ID;
+	buf[1] = 1;
+	buf[2] = 0;
+
+	/* Twiddle arch-specific bits needed for _PDC */
+	arch_acpi_set_proc_cap_bits(&buf[2]);
+}
+
+static struct acpi_object_list *acpi_processor_alloc_pdc(void)
+{
+	struct acpi_object_list *obj_list;
+	union acpi_object *obj;
+	u32 *buf;
+
+	/* allocate and initialize pdc. It will be used later. */
+	obj_list = kmalloc(sizeof(struct acpi_object_list), GFP_KERNEL);
+	if (!obj_list)
+		goto out;
+
+	obj = kmalloc(sizeof(union acpi_object), GFP_KERNEL);
+	if (!obj) {
+		kfree(obj_list);
+		goto out;
+	}
+
+	buf = kmalloc(12, GFP_KERNEL);
+	if (!buf) {
+		kfree(obj);
+		kfree(obj_list);
+		goto out;
+	}
+
+	acpi_set_pdc_bits(buf);
+
+	obj->type = ACPI_TYPE_BUFFER;
+	obj->buffer.length = 12;
+	obj->buffer.pointer = (u8 *) buf;
+	obj_list->count = 1;
+	obj_list->pointer = obj;
+
+	return obj_list;
+out:
+	pr_err("Memory allocation error\n");
+	return NULL;
+}
+
+/*
+ * _PDC is required for a BIOS-OS handshake for most of the newer
+ * ACPI processor features.
+ */
+static acpi_status
+acpi_processor_eval_pdc(acpi_handle handle, struct acpi_object_list *pdc_in)
+{
+	acpi_status status = AE_OK;
+
+	status = acpi_evaluate_object(handle, "_PDC", pdc_in, NULL);
+
+	if (ACPI_FAILURE(status))
+		acpi_handle_debug(handle,
+		    "Could not evaluate _PDC, using legacy perf control\n");
+
+	return status;
+}
+
+void acpi_processor_set_pdc(acpi_handle handle)
+{
+	struct acpi_object_list *obj_list;
+
+	if (arch_has_acpi_pdc() == false)
+		return;
+
+	obj_list = acpi_processor_alloc_pdc();
+	if (!obj_list)
+		return;
+
+	acpi_processor_eval_pdc(handle, obj_list);
+
+	kfree(obj_list->pointer->buffer.pointer);
+	kfree(obj_list->pointer);
+	kfree(obj_list);
+}
+
+static acpi_status __init
+early_init_pdc(acpi_handle handle, u32 lvl, void *context, void **rv)
+{
+	if (processor_physically_present(handle) == false)
+		return AE_OK;
+
+	acpi_processor_set_pdc(handle);
+	return AE_OK;
+}
+
+void __init acpi_early_processor_set_pdc(void)
+{
+	acpi_proc_quirk_mwait_check();
+
+	acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
+			    ACPI_UINT32_MAX,
+			    early_init_pdc, NULL, NULL, NULL);
+	acpi_get_devices(ACPI_PROCESSOR_DEVICE_HID, early_init_pdc, NULL, NULL);
+}