soc/mediatek/mt8196: Add dynamic power-saving for peripheral clocks

In MT8196, CKSYS achieves power efficiency by dynamically turning the
clocks on or off based on the status provided by PERI.

TEST=Build pass, boot log:
mtk_cksys_init = 0x1
BUG=b:317009620

Change-Id: I70f710f068d7d882037691930a90c83adaab15d2
Signed-off-by: Jarried Lin <jarried.lin@mediatek.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/85774
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yidi Lin <yidilin@google.com>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>

src/soc/mediatek/mt8196/Makefile.mk

@@ -13,6 +13,7 @@ all-y += ../common/uart.c
 bootblock-y += booker.c
 bootblock-y += bootblock.c
 bootblock-y += ../common/bootblock.c bootblock.c
+bootblock-y += cksys.c
 bootblock-y += ../common/early_init.c
 bootblock-y += ../common/lastbus_v2.c lastbus.c
 bootblock-y += mminfra.c

src/soc/mediatek/mt8196/bootblock.c

@@ -2,6 +2,7 @@
 
 #include <soc/booker.h>
 #include <bootblock_common.h>
+#include <soc/cksys.h>
 #include <soc/early_init.h>
 #include <soc/lastbus_v2.h>
 #include <soc/mminfra.h>
@@ -14,6 +15,7 @@
 void bootblock_soc_init(void)
 {
 	booker_init();
+	mtk_cksys_init();
 	mtk_mmu_init();
 	bustracker_init();
 	lastbus_init();

src/soc/mediatek/mt8196/cksys.c

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-only OR MIT */
+
+#include <console/console.h>
+#include <device/mmio.h>
+#include <soc/addressmap.h>
+#include <soc/cksys.h>
+
+#define CKSYS_OFFSET	0x270
+#define PERI_MASK_IDLE_TO_CKSYS	(PERICFG_AO_SEC_BASE + CKSYS_OFFSET)
+
+void mtk_cksys_init(void)
+{
+	setbits32p(PERI_MASK_IDLE_TO_CKSYS, BIT(0));
+	printk(BIOS_INFO, "%s = %#x\n", __func__, read32p(PERI_MASK_IDLE_TO_CKSYS));
+}

src/soc/mediatek/mt8196/include/soc/cksys.h

@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-only OR MIT */
+
+#ifndef __SOC_MEDIATEK_MT8196_CKSYS_H__
+#define __SOC_MEDIATEK_MT8196_CKSYS_H__
+
+void mtk_cksys_init(void);
+
+#endif /* __SOC_MEDIATEK_MT8196_CKSYS_H__ */