wifi: rtw89: introduce realtek ACPI DSM method

Introduce realtek ACPI DSM method to get required BIOS
configurations. It will be used in the following commits.

And, enum rtw89_acpi_dsm_func is added for listing the functions
which are currently recognized.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230508081211.38760-2-pkshih@realtek.com

drivers/net/wireless/realtek/rtw89/Makefile

@@ -13,7 +13,8 @@ rtw89_core-y += core.o \
 		coex.o \
 		ps.o \
 		chan.o \
-		ser.o
+		ser.o \
+		acpi.o
 
 rtw89_core-$(CONFIG_PM) += wow.o
 

drivers/net/wireless/realtek/rtw89/acpi.c

@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/* Copyright(c) 2021-2023  Realtek Corporation
+ */
+
+#include <linux/acpi.h>
+#include <linux/uuid.h>
+
+#include "acpi.h"
+#include "debug.h"
+
+static const guid_t rtw89_guid = GUID_INIT(0xD2A8C3E8, 0x4B69, 0x4F00,
+					   0x82, 0xBD, 0xFE, 0x86,
+					   0x07, 0x80, 0x3A, 0xA7);
+
+static int rtw89_acpi_dsm_get(struct rtw89_dev *rtwdev, union acpi_object *obj,
+			      u8 *value)
+{
+	switch (obj->type) {
+	case ACPI_TYPE_INTEGER:
+		*value = (u8)obj->integer.value;
+		break;
+	case ACPI_TYPE_BUFFER:
+		*value = obj->buffer.pointer[0];
+		break;
+	default:
+		rtw89_debug(rtwdev, RTW89_DBG_UNEXP,
+			    "acpi dsm return unhandled type: %d\n", obj->type);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int rtw89_acpi_evaluate_dsm(struct rtw89_dev *rtwdev,
+			    enum rtw89_acpi_dsm_func func, u8 *value)
+{
+	union acpi_object *obj;
+	int ret;
+
+	obj = acpi_evaluate_dsm(ACPI_HANDLE(rtwdev->dev), &rtw89_guid,
+				0, func, NULL);
+	if (!obj) {
+		rtw89_debug(rtwdev, RTW89_DBG_UNEXP,
+			    "acpi dsm fail to evaluate func: %d\n", func);
+		return -ENOENT;
+	}
+
+	ret = rtw89_acpi_dsm_get(rtwdev, obj, value);
+
+	ACPI_FREE(obj);
+	return ret;
+}

drivers/net/wireless/realtek/rtw89/acpi.h

@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause */
+/* Copyright(c) 2021-2023  Realtek Corporation
+ */
+
+#ifndef __RTW89_ACPI_H__
+#define __RTW89_ACPI_H__
+
+#include "core.h"
+
+enum rtw89_acpi_dsm_func {
+	RTW89_ACPI_DSM_FUNC_IDN_BAND_SUP = 2,
+	RTW89_ACPI_DSM_FUNC_6G_DIS = 3,
+	RTW89_ACPI_DSM_FUNC_6G_BP = 4,
+	RTW89_ACPI_DSM_FUNC_TAS_EN = 5,
+	RTW89_ACPI_DSM_FUNC_59G_EN = 6,
+};
+
+int rtw89_acpi_evaluate_dsm(struct rtw89_dev *rtwdev,
+			    enum rtw89_acpi_dsm_func func, u8 *value);
+
+#endif