arm: airoha: introduce AN7581 helpers to get SCU and CHIP_SCU regmaps

We need access SCU and CHIP_SCU regmaps in several places (clk-airoha,
reset-airoha, airoha_eth). Unfortunately these regmaps can't be easily
retrieved with a common code, because of different Airoha SoCs uses
a different dts structure.

To make life easy we can write a commonly named SoC specific helpers
for these tasks. This patch implements helpers for Airoha AN7581 SoC.

Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>

arch/arm/include/asm/arch-airoha/scu-regmap.h

@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Author: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
+ */
+#ifndef __AIROHA_SCU_REGMAP__
+#define __AIROHA_SCU_REGMAP__
+
+#include <regmap.h>
+
+struct regmap *airoha_get_scu_regmap(void);
+struct regmap *airoha_get_chip_scu_regmap(void);
+
+#endif

arch/arm/include/asm/arch-an7581

@@ -0,0 +1 @@
+arch-airoha

arch/arm/mach-airoha/an7581/Makefile

@@ -1,3 +1,4 @@
 # SPDX-License-Identifier:	GPL-2.0
 
 obj-y += init.o
+obj-y += scu-regmap.o

arch/arm/mach-airoha/an7581/scu-regmap.c

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Author: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
+ */
+
+#include <syscon.h>
+#include <linux/err.h>
+#include <asm/arch/scu-regmap.h>
+
+struct regmap *airoha_get_scu_regmap(void)
+{
+	ofnode node;
+
+	node = ofnode_by_compatible(ofnode_null(), "airoha,en7581-scu");
+	if (!ofnode_valid(node))
+		return ERR_PTR(-EINVAL);
+
+	return syscon_node_to_regmap(node);
+}
+
+struct regmap *airoha_get_chip_scu_regmap(void)
+{
+	ofnode node;
+
+	node = ofnode_by_compatible(ofnode_null(), "airoha,en7581-chip-scu");
+	if (!ofnode_valid(node))
+		return ERR_PTR(-EINVAL);
+
+	return syscon_node_to_regmap(node);
+}