[deliverable/linux.git] / drivers / firmware / psci.c

/*
 * 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/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 <uapi/linux/psci.h>

#include <asm/cputype.h>
#include <asm/system_misc.h>
#include <asm/smp_plat.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_0_2_FN_NATIVE(x) will choose the appropriate (native-width)
 * function ID.
 */
#ifdef CONFIG_64BIT
#define PSCI_0_2_FN_NATIVE(name)	PSCI_0_2_FN64_##name
#else
#define PSCI_0_2_FN_NATIVE(name)	PSCI_0_2_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;

typedef unsigned long (psci_fn)(unsigned long, unsigned long,
				unsigned long, unsigned long);
asmlinkage psci_fn __invoke_psci_fn_hvc;
asmlinkage psci_fn __invoke_psci_fn_smc;
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];

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:
		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_0_2_FN_NATIVE(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_0_2_FN_NATIVE(MIGRATE_INFO_UP_CPU),
			      0, 0, 0);
}

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)) {
		invoke_psci_fn = __invoke_psci_fn_hvc;
	} else if (!strcmp("smc", method)) {
		invoke_psci_fn = __invoke_psci_fn_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)
{
	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);
}

/*
 * 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_0_2_set_functions(void)
{
	pr_info("Using standard PSCI v0.2 function IDs\n");
	psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_0_2_FN_NATIVE(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_0_2_FN_NATIVE(CPU_ON);
	psci_ops.cpu_on = psci_cpu_on;

	psci_function_id[PSCI_FN_MIGRATE] = PSCI_0_2_FN_NATIVE(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();

	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)
		goto out_put_node;
	/*
	 * 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
	 */
	err = psci_probe();

out_put_node:
	of_node_put(np);
	return err;
}

/*
 * 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)
		goto out_put_node;

	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;
	}

out_put_node:
	of_node_put(np);
	return err;
}

static const struct of_device_id const psci_of_match[] __initconst = {
	{ .compatible = "arm,psci",	.data = psci_0_1_init},
	{ .compatible = "arm,psci-0.2",	.data = psci_0_2_init},
	{},
};

int __init psci_dt_init(void)
{
	struct device_node *np;
	const struct of_device_id *matched_np;
	psci_initcall_t init_fn;

	np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);

	if (!np)
		return -ENODEV;

	init_fn = (psci_initcall_t)matched_np->data;
	return init_fn(np);
}

#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())
		invoke_psci_fn = __invoke_psci_fn_hvc;
	else
		invoke_psci_fn = __invoke_psci_fn_smc;

	return psci_probe();
}
#endif
Commit	Line	Data
bff60792 MR	1	/*
	2	* This program is free software; you can redistribute it and/or modify
	3	* it under the terms of the GNU General Public License version 2 as
	4	* published by the Free Software Foundation.
	5	*
	6	* This program is distributed in the hope that it will be useful,
	7	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	8	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	9	* GNU General Public License for more details.
	10	*
	11	* Copyright (C) 2015 ARM Limited
	12	*/
	13
	14	#define pr_fmt(fmt) "psci: " fmt
	15
	16	#include <linux/errno.h>
	17	#include <linux/linkage.h>
	18	#include <linux/of.h>
	19	#include <linux/pm.h>
	20	#include <linux/printk.h>
	21	#include <linux/psci.h>
	22	#include <linux/reboot.h>
	23
	24	#include <uapi/linux/psci.h>
	25
	26	#include <asm/cputype.h>
	27	#include <asm/system_misc.h>
	28	#include <asm/smp_plat.h>
	29
5211df00 MR	30	/*
	31	* While a 64-bit OS can make calls with SMC32 calling conventions, for some
	32	* calls it is necessary to use SMC64 to pass or return 64-bit values. For such
	33	* calls PSCI_0_2_FN_NATIVE(x) will choose the appropriate (native-width)
	34	* function ID.
	35	*/
	36	#ifdef CONFIG_64BIT
	37	#define PSCI_0_2_FN_NATIVE(name) PSCI_0_2_FN64_##name
	38	#else
	39	#define PSCI_0_2_FN_NATIVE(name) PSCI_0_2_FN_##name
	40	#endif
	41
bff60792 MR	42	/*
	43	* The CPU any Trusted OS is resident on. The trusted OS may reject CPU_OFF
	44	* calls to its resident CPU, so we must avoid issuing those. We never migrate
	45	* a Trusted OS even if it claims to be capable of migration -- doing so will
	46	* require cooperation with a Trusted OS driver.
	47	*/
	48	static int resident_cpu = -1;
	49
	50	bool psci_tos_resident_on(int cpu)
	51	{
	52	return cpu == resident_cpu;
	53	}
	54
	55	struct psci_operations psci_ops;
	56
	57	typedef unsigned long (psci_fn)(unsigned long, unsigned long,
	58	unsigned long, unsigned long);
	59	asmlinkage psci_fn __invoke_psci_fn_hvc;
	60	asmlinkage psci_fn __invoke_psci_fn_smc;
	61	static psci_fn *invoke_psci_fn;
	62
	63	enum psci_function {
	64	PSCI_FN_CPU_SUSPEND,
	65	PSCI_FN_CPU_ON,
	66	PSCI_FN_CPU_OFF,
	67	PSCI_FN_MIGRATE,
	68	PSCI_FN_MAX,
	69	};
	70
	71	static u32 psci_function_id[PSCI_FN_MAX];
	72
	73	static int psci_to_linux_errno(int errno)
	74	{
	75	switch (errno) {
	76	case PSCI_RET_SUCCESS:
	77	return 0;
	78	case PSCI_RET_NOT_SUPPORTED:
	79	return -EOPNOTSUPP;
	80	case PSCI_RET_INVALID_PARAMS:
	81	return -EINVAL;
	82	case PSCI_RET_DENIED:
	83	return -EPERM;
	84	};
	85
	86	return -EINVAL;
	87	}
	88
	89	static u32 psci_get_version(void)
	90	{
	91	return invoke_psci_fn(PSCI_0_2_FN_PSCI_VERSION, 0, 0, 0);
	92	}
	93
	94	static int psci_cpu_suspend(u32 state, unsigned long entry_point)
	95	{
	96	int err;
	97	u32 fn;
	98
	99	fn = psci_function_id[PSCI_FN_CPU_SUSPEND];
	100	err = invoke_psci_fn(fn, state, entry_point, 0);
	101	return psci_to_linux_errno(err);
	102	}
	103
	104	static int psci_cpu_off(u32 state)
	105	{
106	int err;
107	u32 fn;
108
109	fn = psci_function_id[PSCI_FN_CPU_OFF];
110	err = invoke_psci_fn(fn, state, 0, 0);
111	return psci_to_linux_errno(err);
112	}
113
114	static int psci_cpu_on(unsigned long cpuid, unsigned long entry_point)
115	{
116	int err;
117	u32 fn;
118
119	fn = psci_function_id[PSCI_FN_CPU_ON];
120	err = invoke_psci_fn(fn, cpuid, entry_point, 0);
121	return psci_to_linux_errno(err);
122	}
123
124	static int psci_migrate(unsigned long cpuid)
125	{
126	int err;
127	u32 fn;
128
129	fn = psci_function_id[PSCI_FN_MIGRATE];
130	err = invoke_psci_fn(fn, cpuid, 0, 0);
131	return psci_to_linux_errno(err);
132	}
133
134	static int psci_affinity_info(unsigned long target_affinity,
135	unsigned long lowest_affinity_level)
136	{
5211df00 MR	137	return invoke_psci_fn(PSCI_0_2_FN_NATIVE(AFFINITY_INFO),
5211df00 MR	138	target_affinity, lowest_affinity_level, 0);
bff60792 MR	139	}
	140
	141	static int psci_migrate_info_type(void)
	142	{
	143	return invoke_psci_fn(PSCI_0_2_FN_MIGRATE_INFO_TYPE, 0, 0, 0);
	144	}
	145
	146	static unsigned long psci_migrate_info_up_cpu(void)
	147	{
5211df00 MR	148	return invoke_psci_fn(PSCI_0_2_FN_NATIVE(MIGRATE_INFO_UP_CPU),
5211df00 MR	149	0, 0, 0);
bff60792 MR	150	}
	151
	152	static int get_set_conduit_method(struct device_node *np)
	153	{
	154	const char *method;
	155
	156	pr_info("probing for conduit method from DT.\n");
	157
	158	if (of_property_read_string(np, "method", &method)) {
	159	pr_warn("missing \"method\" property\n");
	160	return -ENXIO;
	161	}
	162
	163	if (!strcmp("hvc", method)) {
	164	invoke_psci_fn = __invoke_psci_fn_hvc;
	165	} else if (!strcmp("smc", method)) {
	166	invoke_psci_fn = __invoke_psci_fn_smc;
	167	} else {
	168	pr_warn("invalid \"method\" property: %s\n", method);
	169	return -EINVAL;
	170	}
	171	return 0;
	172	}
	173
	174	static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
	175	{
	176	invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
	177	}
	178
	179	static void psci_sys_poweroff(void)
	180	{
	181	invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
	182	}
	183
	184	/*
	185	* Detect the presence of a resident Trusted OS which may cause CPU_OFF to
	186	* return DENIED (which would be fatal).
	187	*/
	188	static void __init psci_init_migrate(void)
	189	{
	190	unsigned long cpuid;
	191	int type, cpu = -1;
	192
	193	type = psci_ops.migrate_info_type();
	194
	195	if (type == PSCI_0_2_TOS_MP) {
	196	pr_info("Trusted OS migration not required\n");
	197	return;
	198	}
	199
	200	if (type == PSCI_RET_NOT_SUPPORTED) {
	201	pr_info("MIGRATE_INFO_TYPE not supported.\n");
	202	return;
	203	}
	204
	205	if (type != PSCI_0_2_TOS_UP_MIGRATE &&
	206	type != PSCI_0_2_TOS_UP_NO_MIGRATE) {
	207	pr_err("MIGRATE_INFO_TYPE returned unknown type (%d)\n", type);
	208	return;
	209	}
	210
	211	cpuid = psci_migrate_info_up_cpu();
	212	if (cpuid & ~MPIDR_HWID_BITMASK) {
	213	pr_warn("MIGRATE_INFO_UP_CPU reported invalid physical ID (0x%lx)\n",
214	cpuid);
215	return;
216	}
217
218	cpu = get_logical_index(cpuid);
219	resident_cpu = cpu >= 0 ? cpu : -1;
220
221	pr_info("Trusted OS resident on physical CPU 0x%lx\n", cpuid);
222	}
223
224	static void __init psci_0_2_set_functions(void)
225	{
226	pr_info("Using standard PSCI v0.2 function IDs\n");
5211df00	227	psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_0_2_FN_NATIVE(CPU_SUSPEND);
bff60792 MR	228	psci_ops.cpu_suspend = psci_cpu_suspend;
	229
	230	psci_function_id[PSCI_FN_CPU_OFF] = PSCI_0_2_FN_CPU_OFF;
	231	psci_ops.cpu_off = psci_cpu_off;
	232
5211df00	233	psci_function_id[PSCI_FN_CPU_ON] = PSCI_0_2_FN_NATIVE(CPU_ON);
bff60792 MR	234	psci_ops.cpu_on = psci_cpu_on;
bff60792 MR	235
5211df00	236	psci_function_id[PSCI_FN_MIGRATE] = PSCI_0_2_FN_NATIVE(MIGRATE);
bff60792 MR	237	psci_ops.migrate = psci_migrate;
	238
	239	psci_ops.affinity_info = psci_affinity_info;
	240
	241	psci_ops.migrate_info_type = psci_migrate_info_type;
	242
	243	arm_pm_restart = psci_sys_reset;
	244
	245	pm_power_off = psci_sys_poweroff;
	246	}
	247
	248	/*
	249	* Probe function for PSCI firmware versions >= 0.2
	250	*/
	251	static int __init psci_probe(void)
	252	{
	253	u32 ver = psci_get_version();
	254
	255	pr_info("PSCIv%d.%d detected in firmware.\n",
	256	PSCI_VERSION_MAJOR(ver),
	257	PSCI_VERSION_MINOR(ver));
	258
	259	if (PSCI_VERSION_MAJOR(ver) == 0 && PSCI_VERSION_MINOR(ver) < 2) {
	260	pr_err("Conflicting PSCI version detected.\n");
	261	return -EINVAL;
	262	}
	263
	264	psci_0_2_set_functions();
	265
	266	psci_init_migrate();
	267
	268	return 0;
	269	}
	270
	271	typedef int (psci_initcall_t)(const struct device_node );
	272
	273	/*
	274	* PSCI init function for PSCI versions >=0.2
	275	*
	276	* Probe based on PSCI PSCI_VERSION function
	277	*/
	278	static int __init psci_0_2_init(struct device_node *np)
	279	{
	280	int err;
	281
	282	err = get_set_conduit_method(np);
	283
	284	if (err)
	285	goto out_put_node;
	286	/*
	287	* Starting with v0.2, the PSCI specification introduced a call
	288	* (PSCI_VERSION) that allows probing the firmware version, so
	289	* that PSCI function IDs and version specific initialization
	290	* can be carried out according to the specific version reported
	291	* by firmware
	292	*/
	293	err = psci_probe();
	294
	295	out_put_node:
	296	of_node_put(np);
	297	return err;
	298	}
	299
	300	/*
301	* PSCI < v0.2 get PSCI Function IDs via DT.
302	*/
303	static int __init psci_0_1_init(struct device_node *np)
304	{
305	u32 id;
306	int err;
307
308	err = get_set_conduit_method(np);
309
310	if (err)
311	goto out_put_node;
312
313	pr_info("Using PSCI v0.1 Function IDs from DT\n");
314
315	if (!of_property_read_u32(np, "cpu_suspend", &id)) {
316	psci_function_id[PSCI_FN_CPU_SUSPEND] = id;
317	psci_ops.cpu_suspend = psci_cpu_suspend;
318	}
319
320	if (!of_property_read_u32(np, "cpu_off", &id)) {
321	psci_function_id[PSCI_FN_CPU_OFF] = id;
322	psci_ops.cpu_off = psci_cpu_off;
323	}
324
325	if (!of_property_read_u32(np, "cpu_on", &id)) {
326	psci_function_id[PSCI_FN_CPU_ON] = id;
327	psci_ops.cpu_on = psci_cpu_on;
328	}
329
330	if (!of_property_read_u32(np, "migrate", &id)) {
331	psci_function_id[PSCI_FN_MIGRATE] = id;
332	psci_ops.migrate = psci_migrate;
333	}
334
335	out_put_node:
336	of_node_put(np);
337	return err;
338	}
339
c706c7eb	340	static const struct of_device_id const psci_of_match[] __initconst = {
bff60792 MR	341	{ .compatible = "arm,psci", .data = psci_0_1_init},
	342	{ .compatible = "arm,psci-0.2", .data = psci_0_2_init},
	343	{},
	344	};
	345
	346	int __init psci_dt_init(void)
	347	{
	348	struct device_node *np;
	349	const struct of_device_id *matched_np;
	350	psci_initcall_t init_fn;
	351
	352	np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);
	353
	354	if (!np)
	355	return -ENODEV;
	356
	357	init_fn = (psci_initcall_t)matched_np->data;
	358	return init_fn(np);
	359	}
	360
	361	#ifdef CONFIG_ACPI
	362	/*
	363	* We use PSCI 0.2+ when ACPI is deployed on ARM64 and it's
	364	* explicitly clarified in SBBR
	365	*/
	366	int __init psci_acpi_init(void)
	367	{
	368	if (!acpi_psci_present()) {
	369	pr_info("is not implemented in ACPI.\n");
	370	return -EOPNOTSUPP;
	371	}
	372
	373	pr_info("probing for conduit method from ACPI.\n");
	374
	375	if (acpi_psci_use_hvc())
	376	invoke_psci_fn = __invoke_psci_fn_hvc;
	377	else
	378	invoke_psci_fn = __invoke_psci_fn_smc;
	379
	380	return psci_probe();
	381	}
	382	#endif