mb/google/geralt: Raise little core CPU frequency from 500MHz to 2GHz

To improve boot time, raise little CPU from 500MHz to 2GHz at romstage
(before DRAM calibration).

FW logs:
Check CPU freq: 1999968 KHz, cci: 1600012 KHz

TEST=cpu freq and cci freq run correctly.
BUG=b:244251006

Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Change-Id: Ic1bed53669baa15f797c9a952455376a39d29cf3
Reviewed-on: https://review.coreboot.org/c/coreboot/+/67544
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/geralt/Makefile.inc

@@ -8,6 +8,7 @@ verstage-y += reset.c
 
 romstage-y += memlayout.ld
 romstage-y += chromeos.c
+romstage-y += regulator.c
 romstage-y += romstage.c
 romstage-y += sdram_configs.c
 

src/mainboard/google/geralt/romstage.c

@@ -1,18 +1,36 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
 #include <arch/stages.h>
+#include <console/console.h>
+#include <delay.h>
 #include <soc/clkbuf.h>
 #include <soc/emi.h>
 #include <soc/mt6315.h>
 #include <soc/mt6359p.h>
+#include <soc/pll_common.h>
 #include <soc/pmif.h>
+#include <soc/regulator.h>
 #include <soc/rtc.h>
 
+static void raise_little_cpu_freq(void)
+{
+	mainboard_set_regulator_voltage(MTK_REGULATOR_VPROC11, 900000);
+	mainboard_set_regulator_voltage(MTK_REGULATOR_VSRAM_PROC11, 1000000);
+	udelay(200);
+	mt_pll_raise_little_cpu_freq(2000 * MHz);
+	mt_pll_raise_cci_freq(1600 * MHz);
+
+	printk(BIOS_INFO, "Check CPU freq: %u KHz, cci: %u KHz\n",
+	       mt_fmeter_get_freq_khz(FMETER_ABIST, 1),
+	       mt_fmeter_get_freq_khz(FMETER_ABIST, 3));
+}
+
 void platform_romstage_main(void)
 {
 	mtk_pmif_init();
 	mt6315_init();
 	mt6359p_init();
+	raise_little_cpu_freq();
 	clk_buf_init();
 	rtc_boot();
 	mtk_dram_init();