1 files changed, 750 insertions, 0 deletions

diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
new file mode 100644
index 000000000000..fe090ef43d28
--- /dev/null
+++ b/drivers/firmware/psci/psci.c
@@ -0,0 +1,750 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Copyright (C) 2015 ARM Limited
+ */
+
+#define pr_fmt(fmt) "psci: " fmt
+
+#include <linux/acpi.h>
+#include <linux/arm-smccc.h>
+#include <linux/cpuidle.h>
+#include <linux/errno.h>
+#include <linux/linkage.h>
+#include <linux/of.h>
+#include <linux/pm.h>
+#include <linux/printk.h>
+#include <linux/psci.h>
+#include <linux/reboot.h>
+#include <linux/slab.h>
+#include <linux/suspend.h>
+
+#include <uapi/linux/psci.h>
+
+#include <asm/cpuidle.h>
+#include <asm/cputype.h>
+#include <asm/system_misc.h>
+#include <asm/smp_plat.h>
+#include <asm/suspend.h>
+
+/*
+ * While a 64-bit OS can make calls with SMC32 calling conventions, for some
+ * calls it is necessary to use SMC64 to pass or return 64-bit values.
+ * For such calls PSCI_FN_NATIVE(version, name) will choose the appropriate
+ * (native-width) function ID.
+ */
+#ifdef CONFIG_64BIT
+#define PSCI_FN_NATIVE(version, name)   PSCI_##version##_FN64_##name
+#else
+#define PSCI_FN_NATIVE(version, name)   PSCI_##version##_FN_##name
+#endif
+
+/*
+ * The CPU any Trusted OS is resident on. The trusted OS may reject CPU_OFF
+ * calls to its resident CPU, so we must avoid issuing those. We never migrate
+ * a Trusted OS even if it claims to be capable of migration -- doing so will
+ * require cooperation with a Trusted OS driver.
+ */
+static int resident_cpu = -1;
+
+bool psci_tos_resident_on(int cpu)
+{
+        return cpu == resident_cpu;
+}
+
+struct psci_operations psci_ops = {
+        .conduit = PSCI_CONDUIT_NONE,
+        .smccc_version = SMCCC_VERSION_1_0,
+};
+
+typedef unsigned long (psci_fn)(unsigned long, unsigned long,
+                                unsigned long, unsigned long);
+static psci_fn *invoke_psci_fn;
+
+enum psci_function {
+        PSCI_FN_CPU_SUSPEND,
+        PSCI_FN_CPU_ON,
+        PSCI_FN_CPU_OFF,
+        PSCI_FN_MIGRATE,
+        PSCI_FN_MAX,
+};
+
+static u32 psci_function_id[PSCI_FN_MAX];
+
+#define PSCI_0_2_POWER_STATE_MASK               \
+                                (PSCI_0_2_POWER_STATE_ID_MASK | \
+                                PSCI_0_2_POWER_STATE_TYPE_MASK | \
+                                PSCI_0_2_POWER_STATE_AFFL_MASK)
+
+#define PSCI_1_0_EXT_POWER_STATE_MASK           \
+                                (PSCI_1_0_EXT_POWER_STATE_ID_MASK | \
+                                PSCI_1_0_EXT_POWER_STATE_TYPE_MASK)
+
+static u32 psci_cpu_suspend_feature;
+static bool psci_system_reset2_supported;
+
+static inline bool psci_has_ext_power_state(void)
+{
+        return psci_cpu_suspend_feature &
+                                PSCI_1_0_FEATURES_CPU_SUSPEND_PF_MASK;
+}
+
+static inline bool psci_has_osi_support(void)
+{
+        return psci_cpu_suspend_feature & PSCI_1_0_OS_INITIATED;
+}
+
+static inline bool psci_power_state_loses_context(u32 state)
+{
+        const u32 mask = psci_has_ext_power_state() ?
+                                        PSCI_1_0_EXT_POWER_STATE_TYPE_MASK :
+                                        PSCI_0_2_POWER_STATE_TYPE_MASK;
+
+        return state & mask;
+}
+
+static inline bool psci_power_state_is_valid(u32 state)
+{
+        const u32 valid_mask = psci_has_ext_power_state() ?
+                               PSCI_1_0_EXT_POWER_STATE_MASK :
+                               PSCI_0_2_POWER_STATE_MASK;
+
+        return !(state & ~valid_mask);
+}
+
+static unsigned long __invoke_psci_fn_hvc(unsigned long function_id,
+                        unsigned long arg0, unsigned long arg1,
+                        unsigned long arg2)
+{
+        struct arm_smccc_res res;
+
+        arm_smccc_hvc(function_id, arg0, arg1, arg2, 0, 0, 0, 0, &res);
+        return res.a0;
+}
+
+static unsigned long __invoke_psci_fn_smc(unsigned long function_id,
+                        unsigned long arg0, unsigned long arg1,
+                        unsigned long arg2)
+{
+        struct arm_smccc_res res;
+
+        arm_smccc_smc(function_id, arg0, arg1, arg2, 0, 0, 0, 0, &res);
+        return res.a0;
+}
+
+static int psci_to_linux_errno(int errno)
+{
+        switch (errno) {
+        case PSCI_RET_SUCCESS:
+                return 0;
+        case PSCI_RET_NOT_SUPPORTED:
+                return -EOPNOTSUPP;
+        case PSCI_RET_INVALID_PARAMS:
+        case PSCI_RET_INVALID_ADDRESS:
+                return -EINVAL;
+        case PSCI_RET_DENIED:
+                return -EPERM;
+        };
+
+        return -EINVAL;
+}
+
+static u32 psci_get_version(void)
+{
+        return invoke_psci_fn(PSCI_0_2_FN_PSCI_VERSION, 0, 0, 0);
+}
+
+static int psci_cpu_suspend(u32 state, unsigned long entry_point)
+{
+        int err;
+        u32 fn;
+
+        fn = psci_function_id[PSCI_FN_CPU_SUSPEND];
+        err = invoke_psci_fn(fn, state, entry_point, 0);
+        return psci_to_linux_errno(err);
+}
+
+static int psci_cpu_off(u32 state)
+{
+        int err;
+        u32 fn;
+
+        fn = psci_function_id[PSCI_FN_CPU_OFF];
+        err = invoke_psci_fn(fn, state, 0, 0);
+        return psci_to_linux_errno(err);
+}
+
+static int psci_cpu_on(unsigned long cpuid, unsigned long entry_point)
+{
+        int err;
+        u32 fn;
+
+        fn = psci_function_id[PSCI_FN_CPU_ON];
+        err = invoke_psci_fn(fn, cpuid, entry_point, 0);
+        return psci_to_linux_errno(err);
+}
+
+static int psci_migrate(unsigned long cpuid)
+{
+        int err;
+        u32 fn;
+
+        fn = psci_function_id[PSCI_FN_MIGRATE];
+        err = invoke_psci_fn(fn, cpuid, 0, 0);
+        return psci_to_linux_errno(err);
+}
+
+static int psci_affinity_info(unsigned long target_affinity,
+                unsigned long lowest_affinity_level)
+{
+        return invoke_psci_fn(PSCI_FN_NATIVE(0_2, AFFINITY_INFO),
+                              target_affinity, lowest_affinity_level, 0);
+}
+
+static int psci_migrate_info_type(void)
+{
+        return invoke_psci_fn(PSCI_0_2_FN_MIGRATE_INFO_TYPE, 0, 0, 0);
+}
+
+static unsigned long psci_migrate_info_up_cpu(void)
+{
+        return invoke_psci_fn(PSCI_FN_NATIVE(0_2, MIGRATE_INFO_UP_CPU),
+                              0, 0, 0);
+}
+
+static void set_conduit(enum psci_conduit conduit)
+{
+        switch (conduit) {
+        case PSCI_CONDUIT_HVC:
+                invoke_psci_fn = __invoke_psci_fn_hvc;
+                break;
+        case PSCI_CONDUIT_SMC:
+                invoke_psci_fn = __invoke_psci_fn_smc;
+                break;
+        default:
+                WARN(1, "Unexpected PSCI conduit %d\n", conduit);
+        }
+
+        psci_ops.conduit = conduit;
+}
+
+static int get_set_conduit_method(struct device_node *np)
+{
+        const char *method;
+
+        pr_info("probing for conduit method from DT.\n");
+
+        if (of_property_read_string(np, "method", &method)) {
+                pr_warn("missing \"method\" property\n");
+                return -ENXIO;
+        }
+
+        if (!strcmp("hvc", method)) {
+                set_conduit(PSCI_CONDUIT_HVC);
+        } else if (!strcmp("smc", method)) {
+                set_conduit(PSCI_CONDUIT_SMC);
+        } else {
+                pr_warn("invalid \"method\" property: %s\n", method);
+                return -EINVAL;
+        }
+        return 0;
+}
+
+static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
+{
+        if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) &&
+            psci_system_reset2_supported) {
+                /*
+                 * reset_type[31] = 0 (architectural)
+                 * reset_type[30:0] = 0 (SYSTEM_WARM_RESET)
+                 * cookie = 0 (ignored by the implementation)
+                 */
+                invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2), 0, 0, 0);
+        } else {
+                invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
+        }
+}
+
+static void psci_sys_poweroff(void)
+{
+        invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
+}
+
+static int __init psci_features(u32 psci_func_id)
+{
+        return invoke_psci_fn(PSCI_1_0_FN_PSCI_FEATURES,
+                              psci_func_id, 0, 0);
+}
+
+#ifdef CONFIG_CPU_IDLE
+static DEFINE_PER_CPU_READ_MOSTLY(u32 *, psci_power_state);
+
+static int psci_dt_parse_state_node(struct device_node *np, u32 *state)
+{
+        int err = of_property_read_u32(np, "arm,psci-suspend-param", state);
+
+        if (err) {
+                pr_warn("%pOF missing arm,psci-suspend-param property\n", np);
+                return err;
+        }
+
+        if (!psci_power_state_is_valid(*state)) {
+                pr_warn("Invalid PSCI power state %#x\n", *state);
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
+static int psci_dt_cpu_init_idle(struct device_node *cpu_node, int cpu)
+{
+        int i, ret = 0, count = 0;
+        u32 *psci_states;
+        struct device_node *state_node;
+
+        /* Count idle states */
+        while ((state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
+                                              count))) {
+                count++;
+                of_node_put(state_node);
+        }
+
+        if (!count)
+                return -ENODEV;
+
+        psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL);
+        if (!psci_states)
+                return -ENOMEM;
+
+        for (i = 0; i < count; i++) {
+                state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
+                ret = psci_dt_parse_state_node(state_node, &psci_states[i]);
+                of_node_put(state_node);
+
+                if (ret)
+                        goto free_mem;
+
+                pr_debug("psci-power-state %#x index %d\n", psci_states[i], i);
+        }
+
+        /* Idle states parsed correctly, initialize per-cpu pointer */
+        per_cpu(psci_power_state, cpu) = psci_states;
+        return 0;
+
+free_mem:
+        kfree(psci_states);
+        return ret;
+}
+
+#ifdef CONFIG_ACPI
+#include <acpi/processor.h>
+
+static int __maybe_unused psci_acpi_cpu_init_idle(unsigned int cpu)
+{
+        int i, count;
+        u32 *psci_states;
+        struct acpi_lpi_state *lpi;
+        struct acpi_processor *pr = per_cpu(processors, cpu);
+
+        if (unlikely(!pr || !pr->flags.has_lpi))
+                return -EINVAL;
+
+        count = pr->power.count - 1;
+        if (count <= 0)
+                return -ENODEV;
+
+        psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL);
+        if (!psci_states)
+                return -ENOMEM;
+
+        for (i = 0; i < count; i++) {
+                u32 state;
+
+                lpi = &pr->power.lpi_states[i + 1];
+                /*
+                 * Only bits[31:0] represent a PSCI power_state while
+                 * bits[63:32] must be 0x0 as per ARM ACPI FFH Specification
+                 */
+                state = lpi->address;
+                if (!psci_power_state_is_valid(state)) {
+                        pr_warn("Invalid PSCI power state %#x\n", state);
+                        kfree(psci_states);
+                        return -EINVAL;
+                }
+                psci_states[i] = state;
+        }
+        /* Idle states parsed correctly, initialize per-cpu pointer */
+        per_cpu(psci_power_state, cpu) = psci_states;
+        return 0;
+}
+#else
+static int __maybe_unused psci_acpi_cpu_init_idle(unsigned int cpu)
+{
+        return -EINVAL;
+}
+#endif
+
+int psci_cpu_init_idle(unsigned int cpu)
+{
+        struct device_node *cpu_node;
+        int ret;
+
+        /*
+         * If the PSCI cpu_suspend function hook has not been initialized
+         * idle states must not be enabled, so bail out
+         */
+        if (!psci_ops.cpu_suspend)
+                return -EOPNOTSUPP;
+
+        if (!acpi_disabled)
+                return psci_acpi_cpu_init_idle(cpu);
+
+        cpu_node = of_get_cpu_node(cpu, NULL);
+        if (!cpu_node)
+                return -ENODEV;
+
+        ret = psci_dt_cpu_init_idle(cpu_node, cpu);
+
+        of_node_put(cpu_node);
+
+        return ret;
+}
+
+static int psci_suspend_finisher(unsigned long index)
+{
+        u32 *state = __this_cpu_read(psci_power_state);
+
+        return psci_ops.cpu_suspend(state[index - 1],
+                                    __pa_symbol(cpu_resume));
+}
+
+int psci_cpu_suspend_enter(unsigned long index)
+{
+        int ret;
+        u32 *state = __this_cpu_read(psci_power_state);
+        /*
+         * idle state index 0 corresponds to wfi, should never be called
+         * from the cpu_suspend operations
+         */
+        if (WARN_ON_ONCE(!index))
+                return -EINVAL;
+
+        if (!psci_power_state_loses_context(state[index - 1]))
+                ret = psci_ops.cpu_suspend(state[index - 1], 0);
+        else
+                ret = cpu_suspend(index, psci_suspend_finisher);
+
+        return ret;
+}
+
+/* ARM specific CPU idle operations */
+#ifdef CONFIG_ARM
+static const struct cpuidle_ops psci_cpuidle_ops __initconst = {
+        .suspend = psci_cpu_suspend_enter,
+        .init = psci_dt_cpu_init_idle,
+};
+
+CPUIDLE_METHOD_OF_DECLARE(psci, "psci", &psci_cpuidle_ops);
+#endif
+#endif
+
+static int psci_system_suspend(unsigned long unused)
+{
+        return invoke_psci_fn(PSCI_FN_NATIVE(1_0, SYSTEM_SUSPEND),
+                              __pa_symbol(cpu_resume), 0, 0);
+}
+
+static int psci_system_suspend_enter(suspend_state_t state)
+{
+        return cpu_suspend(0, psci_system_suspend);
+}
+
+static const struct platform_suspend_ops psci_suspend_ops = {
+        .valid          = suspend_valid_only_mem,
+        .enter          = psci_system_suspend_enter,
+};
+
+static void __init psci_init_system_reset2(void)
+{
+        int ret;
+
+        ret = psci_features(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2));
+
+        if (ret != PSCI_RET_NOT_SUPPORTED)
+                psci_system_reset2_supported = true;
+}
+
+static void __init psci_init_system_suspend(void)
+{
+        int ret;
+
+        if (!IS_ENABLED(CONFIG_SUSPEND))
+                return;
+
+        ret = psci_features(PSCI_FN_NATIVE(1_0, SYSTEM_SUSPEND));
+
+        if (ret != PSCI_RET_NOT_SUPPORTED)
+                suspend_set_ops(&psci_suspend_ops);
+}
+
+static void __init psci_init_cpu_suspend(void)
+{
+        int feature = psci_features(psci_function_id[PSCI_FN_CPU_SUSPEND]);
+
+        if (feature != PSCI_RET_NOT_SUPPORTED)
+                psci_cpu_suspend_feature = feature;
+}
+
+/*
+ * Detect the presence of a resident Trusted OS which may cause CPU_OFF to
+ * return DENIED (which would be fatal).
+ */
+static void __init psci_init_migrate(void)
+{
+        unsigned long cpuid;
+        int type, cpu = -1;
+
+        type = psci_ops.migrate_info_type();
+
+        if (type == PSCI_0_2_TOS_MP) {
+                pr_info("Trusted OS migration not required\n");
+                return;
+        }
+
+        if (type == PSCI_RET_NOT_SUPPORTED) {
+                pr_info("MIGRATE_INFO_TYPE not supported.\n");
+                return;
+        }
+
+        if (type != PSCI_0_2_TOS_UP_MIGRATE &&
+            type != PSCI_0_2_TOS_UP_NO_MIGRATE) {
+                pr_err("MIGRATE_INFO_TYPE returned unknown type (%d)\n", type);
+                return;
+        }
+
+        cpuid = psci_migrate_info_up_cpu();
+        if (cpuid & ~MPIDR_HWID_BITMASK) {
+                pr_warn("MIGRATE_INFO_UP_CPU reported invalid physical ID (0x%lx)\n",
+                        cpuid);
+                return;
+        }
+
+        cpu = get_logical_index(cpuid);
+        resident_cpu = cpu >= 0 ? cpu : -1;
+
+        pr_info("Trusted OS resident on physical CPU 0x%lx\n", cpuid);
+}
+
+static void __init psci_init_smccc(void)
+{
+        u32 ver = ARM_SMCCC_VERSION_1_0;
+        int feature;
+
+        feature = psci_features(ARM_SMCCC_VERSION_FUNC_ID);
+
+        if (feature != PSCI_RET_NOT_SUPPORTED) {
+                u32 ret;
+                ret = invoke_psci_fn(ARM_SMCCC_VERSION_FUNC_ID, 0, 0, 0);
+                if (ret == ARM_SMCCC_VERSION_1_1) {
+                        psci_ops.smccc_version = SMCCC_VERSION_1_1;
+                        ver = ret;
+                }
+        }
+
+        /*
+         * Conveniently, the SMCCC and PSCI versions are encoded the
+         * same way. No, this isn't accidental.
+         */
+        pr_info("SMC Calling Convention v%d.%d\n",
+                PSCI_VERSION_MAJOR(ver), PSCI_VERSION_MINOR(ver));
+
+}
+
+static void __init psci_0_2_set_functions(void)
+{
+        pr_info("Using standard PSCI v0.2 function IDs\n");
+        psci_ops.get_version = psci_get_version;
+
+        psci_function_id[PSCI_FN_CPU_SUSPEND] =
+                                        PSCI_FN_NATIVE(0_2, CPU_SUSPEND);
+        psci_ops.cpu_suspend = psci_cpu_suspend;
+
+        psci_function_id[PSCI_FN_CPU_OFF] = PSCI_0_2_FN_CPU_OFF;
+        psci_ops.cpu_off = psci_cpu_off;
+
+        psci_function_id[PSCI_FN_CPU_ON] = PSCI_FN_NATIVE(0_2, CPU_ON);
+        psci_ops.cpu_on = psci_cpu_on;
+
+        psci_function_id[PSCI_FN_MIGRATE] = PSCI_FN_NATIVE(0_2, MIGRATE);
+        psci_ops.migrate = psci_migrate;
+
+        psci_ops.affinity_info = psci_affinity_info;
+
+        psci_ops.migrate_info_type = psci_migrate_info_type;
+
+        arm_pm_restart = psci_sys_reset;
+
+        pm_power_off = psci_sys_poweroff;
+}
+
+/*
+ * Probe function for PSCI firmware versions >= 0.2
+ */
+static int __init psci_probe(void)
+{
+        u32 ver = psci_get_version();
+
+        pr_info("PSCIv%d.%d detected in firmware.\n",
+                        PSCI_VERSION_MAJOR(ver),
+                        PSCI_VERSION_MINOR(ver));
+
+        if (PSCI_VERSION_MAJOR(ver) == 0 && PSCI_VERSION_MINOR(ver) < 2) {
+                pr_err("Conflicting PSCI version detected.\n");
+                return -EINVAL;
+        }
+
+        psci_0_2_set_functions();
+
+        psci_init_migrate();
+
+        if (PSCI_VERSION_MAJOR(ver) >= 1) {
+                psci_init_smccc();
+                psci_init_cpu_suspend();
+                psci_init_system_suspend();
+                psci_init_system_reset2();
+        }
+
+        return 0;
+}
+
+typedef int (*psci_initcall_t)(const struct device_node *);
+
+/*
+ * PSCI init function for PSCI versions >=0.2
+ *
+ * Probe based on PSCI PSCI_VERSION function
+ */
+static int __init psci_0_2_init(struct device_node *np)
+{
+        int err;
+
+        err = get_set_conduit_method(np);
+        if (err)
+                return err;
+
+        /*
+         * Starting with v0.2, the PSCI specification introduced a call
+         * (PSCI_VERSION) that allows probing the firmware version, so
+         * that PSCI function IDs and version specific initialization
+         * can be carried out according to the specific version reported
+         * by firmware
+         */
+        return psci_probe();
+}
+
+/*
+ * PSCI < v0.2 get PSCI Function IDs via DT.
+ */
+static int __init psci_0_1_init(struct device_node *np)
+{
+        u32 id;
+        int err;
+
+        err = get_set_conduit_method(np);
+        if (err)
+                return err;
+
+        pr_info("Using PSCI v0.1 Function IDs from DT\n");
+
+        if (!of_property_read_u32(np, "cpu_suspend", &id)) {
+                psci_function_id[PSCI_FN_CPU_SUSPEND] = id;
+                psci_ops.cpu_suspend = psci_cpu_suspend;
+        }
+
+        if (!of_property_read_u32(np, "cpu_off", &id)) {
+                psci_function_id[PSCI_FN_CPU_OFF] = id;
+                psci_ops.cpu_off = psci_cpu_off;
+        }
+
+        if (!of_property_read_u32(np, "cpu_on", &id)) {
+                psci_function_id[PSCI_FN_CPU_ON] = id;
+                psci_ops.cpu_on = psci_cpu_on;
+        }
+
+        if (!of_property_read_u32(np, "migrate", &id)) {
+                psci_function_id[PSCI_FN_MIGRATE] = id;
+                psci_ops.migrate = psci_migrate;
+        }
+
+        return 0;
+}
+
+static int __init psci_1_0_init(struct device_node *np)
+{
+        int err;
+
+        err = psci_0_2_init(np);
+        if (err)
+                return err;
+
+        if (psci_has_osi_support())
+                pr_info("OSI mode supported.\n");
+
+        return 0;
+}
+
+static const struct of_device_id psci_of_match[] __initconst = {
+        { .compatible = "arm,psci",     .data = psci_0_1_init},
+        { .compatible = "arm,psci-0.2", .data = psci_0_2_init},
+        { .compatible = "arm,psci-1.0", .data = psci_1_0_init},
+        {},
+};
+
+int __init psci_dt_init(void)
+{
+        struct device_node *np;
+        const struct of_device_id *matched_np;
+        psci_initcall_t init_fn;
+        int ret;
+
+        np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);
+
+        if (!np || !of_device_is_available(np))
+                return -ENODEV;
+
+        init_fn = (psci_initcall_t)matched_np->data;
+        ret = init_fn(np);
+
+        of_node_put(np);
+        return ret;
+}
+
+#ifdef CONFIG_ACPI
+/*
+ * We use PSCI 0.2+ when ACPI is deployed on ARM64 and it's
+ * explicitly clarified in SBBR
+ */
+int __init psci_acpi_init(void)
+{
+        if (!acpi_psci_present()) {
+                pr_info("is not implemented in ACPI.\n");
+                return -EOPNOTSUPP;
+        }
+
+        pr_info("probing for conduit method from ACPI.\n");
+
+        if (acpi_psci_use_hvc())
+                set_conduit(PSCI_CONDUIT_HVC);
+        else
+                set_conduit(PSCI_CONDUIT_SMC);
+
+        return psci_probe();
+}
+#endif