Commit 2bdd424f authored by Will Deacon's avatar Will Deacon
Browse files

ARM: psci: add support for PSCI invocations from the kernel 



This patch adds support for the Power State Coordination Interface
defined by ARM, allowing Linux to request CPU-centric power-management
operations from firmware implementing the PSCI protocol.

Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarNicolas Pitre <nico@linaro.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 65397edf

arch/arm/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -1620,6 +1620,16 @@ config HOTPLUG_CPU 
	  Say Y here to experiment with turning CPUs off and on.  CPUs

	  can be controlled through /sys/devices/system/cpu.



config ARM_PSCI

	bool "Support for the ARM Power State Coordination Interface (PSCI)"

	depends on CPU_V7

	help

	  Say Y here if you want Linux to communicate with system firmware

	  implementing the PSCI specification for CPU-centric power

	  management operations described in ARM document number ARM DEN

	  0022A ("Power State Coordination Interface System Software on

	  ARM processors").



config LOCAL_TIMERS

	bool "Use local timer interrupts"

	depends on SMP

arch/arm/include/asm/psci.h

0 → 100644
+36 −0
Original line number Diff line number Diff line 
/*

 * 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) 2012 ARM Limited

 */



#ifndef __ASM_ARM_PSCI_H

#define __ASM_ARM_PSCI_H



#define PSCI_POWER_STATE_TYPE_STANDBY		0

#define PSCI_POWER_STATE_TYPE_POWER_DOWN	1



struct psci_power_state {

	u16	id;

	u8	type;

	u8	affinity_level;

};



struct psci_operations {

	int (*cpu_suspend)(struct psci_power_state state,

			   unsigned long entry_point);

	int (*cpu_off)(struct psci_power_state state);

	int (*cpu_on)(unsigned long cpuid, unsigned long entry_point);

	int (*migrate)(unsigned long cpuid);

};



extern struct psci_operations psci_ops;



#endif /* __ASM_ARM_PSCI_H */

arch/arm/kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -82,5 +82,6 @@ obj-$(CONFIG_DEBUG_LL) += debug.o 
obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o



obj-$(CONFIG_ARM_VIRT_EXT)	+= hyp-stub.o

obj-$(CONFIG_ARM_PSCI)		+= psci.o



extra-y := $(head-y) vmlinux.lds

arch/arm/kernel/psci.c

0 → 100644
+211 −0
Original line number Diff line number Diff line 
/*

 * 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) 2012 ARM Limited

 *

 * Author: Will Deacon <will.deacon@arm.com>

 */



#define pr_fmt(fmt) "psci: " fmt



#include <linux/init.h>

#include <linux/of.h>



#include <asm/compiler.h>

#include <asm/errno.h>

#include <asm/opcodes-sec.h>

#include <asm/opcodes-virt.h>

#include <asm/psci.h>



struct psci_operations psci_ops;



static int (*invoke_psci_fn)(u32, u32, u32, u32);



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_RET_SUCCESS		0

#define PSCI_RET_EOPNOTSUPP		-1

#define PSCI_RET_EINVAL			-2

#define PSCI_RET_EPERM			-3



static int psci_to_linux_errno(int errno)

{

	switch (errno) {

	case PSCI_RET_SUCCESS:

		return 0;

	case PSCI_RET_EOPNOTSUPP:

		return -EOPNOTSUPP;

	case PSCI_RET_EINVAL:

		return -EINVAL;

	case PSCI_RET_EPERM:

		return -EPERM;

	};



	return -EINVAL;

}



#define PSCI_POWER_STATE_ID_MASK	0xffff

#define PSCI_POWER_STATE_ID_SHIFT	0

#define PSCI_POWER_STATE_TYPE_MASK	0x1

#define PSCI_POWER_STATE_TYPE_SHIFT	16

#define PSCI_POWER_STATE_AFFL_MASK	0x3

#define PSCI_POWER_STATE_AFFL_SHIFT	24



static u32 psci_power_state_pack(struct psci_power_state state)

{

	return	((state.id & PSCI_POWER_STATE_ID_MASK)

			<< PSCI_POWER_STATE_ID_SHIFT)	|

		((state.type & PSCI_POWER_STATE_TYPE_MASK)

			<< PSCI_POWER_STATE_TYPE_SHIFT)	|

		((state.affinity_level & PSCI_POWER_STATE_AFFL_MASK)

			<< PSCI_POWER_STATE_AFFL_SHIFT);

}



/*

 * The following two functions are invoked via the invoke_psci_fn pointer

 * and will not be inlined, allowing us to piggyback on the AAPCS.

 */

static noinline int __invoke_psci_fn_hvc(u32 function_id, u32 arg0, u32 arg1,

					 u32 arg2)

{

	asm volatile(

			__asmeq("%0", "r0")

			__asmeq("%1", "r1")

			__asmeq("%2", "r2")

			__asmeq("%3", "r3")

			__HVC(0)

		: "+r" (function_id)

		: "r" (arg0), "r" (arg1), "r" (arg2));



	return function_id;

}



static noinline int __invoke_psci_fn_smc(u32 function_id, u32 arg0, u32 arg1,

					 u32 arg2)

{

	asm volatile(

			__asmeq("%0", "r0")

			__asmeq("%1", "r1")

			__asmeq("%2", "r2")

			__asmeq("%3", "r3")

			__SMC(0)

		: "+r" (function_id)

		: "r" (arg0), "r" (arg1), "r" (arg2));



	return function_id;

}



static int psci_cpu_suspend(struct psci_power_state state,

			    unsigned long entry_point)

{

	int err;

	u32 fn, power_state;



	fn = psci_function_id[PSCI_FN_CPU_SUSPEND];

	power_state = psci_power_state_pack(state);

	err = invoke_psci_fn(fn, power_state, entry_point, 0);

	return psci_to_linux_errno(err);

}



static int psci_cpu_off(struct psci_power_state state)

{

	int err;

	u32 fn, power_state;



	fn = psci_function_id[PSCI_FN_CPU_OFF];

	power_state = psci_power_state_pack(state);

	err = invoke_psci_fn(fn, power_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 const struct of_device_id psci_of_match[] __initconst = {

	{ .compatible = "arm,psci",	},

	{},

};



static int __init psci_init(void)

{

	struct device_node *np;

	const char *method;

	u32 id;



	np = of_find_matching_node(NULL, psci_of_match);

	if (!np)

		return 0;



	pr_info("probing function IDs from device-tree\n");



	if (of_property_read_string(np, "method", &method)) {

		pr_warning("missing \"method\" property\n");

		goto out_put_node;

	}



	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_warning("invalid \"method\" property: %s\n", method);

		goto out_put_node;

	}



	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 0;

}

early_initcall(psci_init);

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