soc/mediatek/mt8186: Add support for reading CPU ID

MT8186 has two slightly different versions: MT8186G and MT8186T
(turbo version). Add get_cpu_id() to identify different CPUs.

BUG=b:249436110
TEST=cpu id is correct.
BRANCH=corsola

Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Change-Id: I0612dd589e11853dbddc1d99526e9c9bf170acec
Reviewed-on: https://review.coreboot.org/c/coreboot/+/68576
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-by: Yidi Lin <yidilin@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/mediatek/common/cpu_id.c

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <console/console.h>
+#include <device/mmio.h>
+#include <soc/cpu_id.h>
+#include <soc/efuse.h>
+
+u32 get_cpu_id(void)
+{
+	u32 id = read32(&mtk_efuse->cpu_id_reg);
+
+	printk(BIOS_INFO, "CPU: %#x\n", id);
+
+	return id;
+}

src/soc/mediatek/common/include/soc/cpu_id.h

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef SOC_MEDIATEK_COMMON_CPU_ID_H
+#define SOC_MEDIATEK_COMMON_CPU_ID_H
+
+#define MTK_CPU_ID_MT8186G	0x81861001
+#define MTK_CPU_ID_MT8186T	0x81862001
+
+u32 get_cpu_id(void);
+
+#endif /* SOC_MEDIATEK_COMMON_CPU_ID_H */

src/soc/mediatek/mt8186/Makefile.inc

@@ -1,6 +1,7 @@
 ifeq ($(CONFIG_SOC_MEDIATEK_MT8186),y)
 
 # for bootblock, verstage, romstage, ramstage
+all-y += ../common/cpu_id.c
 all-y += ../common/flash_controller.c
 all-y += ../common/gpio.c ../common/gpio_op.c  gpio.c
 all-y += ../common/i2c.c i2c.c

src/soc/mediatek/mt8186/include/soc/efuse.h

@@ -9,9 +9,12 @@
 struct efuse_regs {
 	uint32_t reserved[130];
 	uint32_t adc_cali_reg;
+	uint32_t reserved1[357];
+	uint32_t cpu_id_reg;
 };
 
 check_member(efuse_regs, adc_cali_reg, 0x208);
+check_member(efuse_regs, cpu_id_reg, 0x7a0);
 static struct efuse_regs *const mtk_efuse = (void *)EFUSEC_BASE;
 
 #endif