diff --git a/plat/mediatek/mt8186/drivers/spm/constraints/mt_spm_rc_cpu_buck_ldo.c b/plat/mediatek/mt8186/drivers/spm/constraints/mt_spm_rc_cpu_buck_ldo.c
new file mode 100644
index 0000000..c47cf1f
--- /dev/null
+++ b/plat/mediatek/mt8186/drivers/spm/constraints/mt_spm_rc_cpu_buck_ldo.c
@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2022, MediaTek Inc. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <mt_spm.h>
+#include <mt_spm_cond.h>
+#include <mt_spm_conservation.h>
+#include <mt_spm_constraint.h>
+#include <mt_spm_idle.h>
+#include <mt_spm_internal.h>
+#include <mt_spm_notifier.h>
+#include <mt_spm_rc_internal.h>
+#include <mt_spm_reg.h>
+#include <mt_spm_resource_req.h>
+#include <mt_spm_suspend.h>
+#include <plat_mtk_lpm.h>
+#include <plat_pm.h>
+
+#define CONSTRAINT_CPU_BUCK_PCM_FLAG	\
+	(SPM_FLAG_DISABLE_INFRA_PDN |	\
+	 SPM_FLAG_DISABLE_VCORE_DVS |	\
+	 SPM_FLAG_DISABLE_VCORE_DFS |	\
+	 SPM_FLAG_SRAM_SLEEP_CTRL |	\
+	 SPM_FLAG_KEEP_CSYSPWRACK_HIGH)
+
+#define CONSTRAINT_CPU_BUCK_PCM_FLAG1	(0U)
+
+#define CONSTRAINT_CPU_BUCK_RESOURCE_REQ	\
+	(MT_SPM_DRAM_S1 |			\
+	 MT_SPM_DRAM_S0 |			\
+	 MT_SPM_SYSPLL |			\
+	 MT_SPM_INFRA |				\
+	 MT_SPM_26M |				\
+	 MT_SPM_XO_FPM)
+
+static unsigned int cpubuckldo_status = MT_SPM_RC_VALID_SW;
+static unsigned int cpubuckldo_enter_cnt;
+
+static void spm_cpu_bcuk_ldo_conduct(struct spm_lp_scen *spm_lp,
+				unsigned int *resource_req)
+{
+	spm_lp->pwrctrl->pcm_flags = (uint32_t)CONSTRAINT_CPU_BUCK_PCM_FLAG;
+	spm_lp->pwrctrl->pcm_flags1 = (uint32_t)CONSTRAINT_CPU_BUCK_PCM_FLAG1;
+	*resource_req |= CONSTRAINT_CPU_BUCK_RESOURCE_REQ;
+}
+
+bool spm_is_valid_rc_cpu_buck_ldo(unsigned int cpu, int state_id)
+{
+	(void)cpu;
+	(void)state_id;
+
+	return IS_MT_RM_RC_READY(cpubuckldo_status);
+}
+
+unsigned int spm_allow_rc_cpu_buck_ldo(int state_id)
+{
+	(void)state_id;
+
+	return MT_RM_CONSTRAINT_ALLOW_CPU_BUCK_OFF;
+}
+
+int spm_run_rc_cpu_buck_ldo(unsigned int cpu, int state_id)
+{
+	(void)cpu;
+	unsigned int ext_op = 0U;
+
+#ifndef ATF_PLAT_SPM_SSPM_NOTIFIER_UNSUPPORT
+	mt_spm_sspm_notify_u32(MT_SPM_NOTIFY_LP_ENTER,
+			       (IS_PLAT_SUSPEND_ID(state_id) ?
+				(MT_RM_CONSTRAINT_ALLOW_AP_SUSPEND) : (0U)));
+#endif
+	if (IS_PLAT_SUSPEND_ID(state_id)) {
+		mt_spm_suspend_enter(state_id,
+				     MT_SPM_EX_OP_SET_WDT,
+				     CONSTRAINT_CPU_BUCK_RESOURCE_REQ);
+	} else {
+		mt_spm_idle_generic_enter(state_id, ext_op,
+					  spm_cpu_bcuk_ldo_conduct);
+	}
+
+	cpubuckldo_enter_cnt++;
+
+	return 0;
+}
+
+int spm_reset_rc_cpu_buck_ldo(unsigned int cpu, int state_id)
+{
+	(void)cpu;
+	unsigned int ext_op = 0U;
+
+#ifndef ATF_PLAT_SPM_SSPM_NOTIFIER_UNSUPPORT
+	mt_spm_sspm_notify_u32(MT_SPM_NOTIFY_LP_LEAVE, 0U);
+#endif
+	if (IS_PLAT_SUSPEND_ID(state_id)) {
+		mt_spm_suspend_resume(state_id, MT_SPM_EX_OP_SET_WDT, NULL);
+	} else {
+		mt_spm_idle_generic_resume(state_id, ext_op, NULL, NULL);
+	}
+
+	return 0;
+}