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: Arnd Bergmann <arnd@arndb.de> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
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Will Deacon
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65397edfa1
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2bdd424f26
@ -1620,6 +1620,16 @@ config HOTPLUG_CPU
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Say Y here to experiment with turning CPUs off and on. CPUs
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can be controlled through /sys/devices/system/cpu.
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config ARM_PSCI
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bool "Support for the ARM Power State Coordination Interface (PSCI)"
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depends on CPU_V7
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help
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Say Y here if you want Linux to communicate with system firmware
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implementing the PSCI specification for CPU-centric power
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management operations described in ARM document number ARM DEN
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0022A ("Power State Coordination Interface System Software on
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ARM processors").
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config LOCAL_TIMERS
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bool "Use local timer interrupts"
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depends on SMP
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36
arch/arm/include/asm/psci.h
Normal file
36
arch/arm/include/asm/psci.h
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@ -0,0 +1,36 @@
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/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* Copyright (C) 2012 ARM Limited
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*/
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#ifndef __ASM_ARM_PSCI_H
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#define __ASM_ARM_PSCI_H
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#define PSCI_POWER_STATE_TYPE_STANDBY 0
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#define PSCI_POWER_STATE_TYPE_POWER_DOWN 1
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struct psci_power_state {
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u16 id;
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u8 type;
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u8 affinity_level;
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};
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struct psci_operations {
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int (*cpu_suspend)(struct psci_power_state state,
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unsigned long entry_point);
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int (*cpu_off)(struct psci_power_state state);
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int (*cpu_on)(unsigned long cpuid, unsigned long entry_point);
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int (*migrate)(unsigned long cpuid);
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};
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extern struct psci_operations psci_ops;
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#endif /* __ASM_ARM_PSCI_H */
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@ -82,5 +82,6 @@ obj-$(CONFIG_DEBUG_LL) += debug.o
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obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
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obj-$(CONFIG_ARM_VIRT_EXT) += hyp-stub.o
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obj-$(CONFIG_ARM_PSCI) += psci.o
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extra-y := $(head-y) vmlinux.lds
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211
arch/arm/kernel/psci.c
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211
arch/arm/kernel/psci.c
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@ -0,0 +1,211 @@
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/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* Copyright (C) 2012 ARM Limited
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*
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* Author: Will Deacon <will.deacon@arm.com>
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*/
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#define pr_fmt(fmt) "psci: " fmt
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#include <linux/init.h>
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#include <linux/of.h>
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#include <asm/compiler.h>
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#include <asm/errno.h>
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#include <asm/opcodes-sec.h>
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#include <asm/opcodes-virt.h>
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#include <asm/psci.h>
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struct psci_operations psci_ops;
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static int (*invoke_psci_fn)(u32, u32, u32, u32);
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enum psci_function {
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PSCI_FN_CPU_SUSPEND,
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PSCI_FN_CPU_ON,
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PSCI_FN_CPU_OFF,
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PSCI_FN_MIGRATE,
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PSCI_FN_MAX,
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};
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static u32 psci_function_id[PSCI_FN_MAX];
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#define PSCI_RET_SUCCESS 0
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#define PSCI_RET_EOPNOTSUPP -1
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#define PSCI_RET_EINVAL -2
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#define PSCI_RET_EPERM -3
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static int psci_to_linux_errno(int errno)
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{
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switch (errno) {
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case PSCI_RET_SUCCESS:
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return 0;
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case PSCI_RET_EOPNOTSUPP:
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return -EOPNOTSUPP;
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case PSCI_RET_EINVAL:
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return -EINVAL;
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case PSCI_RET_EPERM:
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return -EPERM;
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};
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return -EINVAL;
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}
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#define PSCI_POWER_STATE_ID_MASK 0xffff
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#define PSCI_POWER_STATE_ID_SHIFT 0
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#define PSCI_POWER_STATE_TYPE_MASK 0x1
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#define PSCI_POWER_STATE_TYPE_SHIFT 16
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#define PSCI_POWER_STATE_AFFL_MASK 0x3
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#define PSCI_POWER_STATE_AFFL_SHIFT 24
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static u32 psci_power_state_pack(struct psci_power_state state)
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{
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return ((state.id & PSCI_POWER_STATE_ID_MASK)
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<< PSCI_POWER_STATE_ID_SHIFT) |
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((state.type & PSCI_POWER_STATE_TYPE_MASK)
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<< PSCI_POWER_STATE_TYPE_SHIFT) |
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((state.affinity_level & PSCI_POWER_STATE_AFFL_MASK)
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<< PSCI_POWER_STATE_AFFL_SHIFT);
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}
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/*
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* The following two functions are invoked via the invoke_psci_fn pointer
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* and will not be inlined, allowing us to piggyback on the AAPCS.
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*/
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static noinline int __invoke_psci_fn_hvc(u32 function_id, u32 arg0, u32 arg1,
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u32 arg2)
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{
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asm volatile(
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__asmeq("%0", "r0")
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__asmeq("%1", "r1")
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__asmeq("%2", "r2")
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__asmeq("%3", "r3")
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__HVC(0)
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: "+r" (function_id)
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: "r" (arg0), "r" (arg1), "r" (arg2));
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return function_id;
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}
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static noinline int __invoke_psci_fn_smc(u32 function_id, u32 arg0, u32 arg1,
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u32 arg2)
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{
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asm volatile(
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__asmeq("%0", "r0")
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__asmeq("%1", "r1")
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__asmeq("%2", "r2")
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__asmeq("%3", "r3")
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__SMC(0)
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: "+r" (function_id)
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: "r" (arg0), "r" (arg1), "r" (arg2));
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return function_id;
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}
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static int psci_cpu_suspend(struct psci_power_state state,
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unsigned long entry_point)
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{
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int err;
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u32 fn, power_state;
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fn = psci_function_id[PSCI_FN_CPU_SUSPEND];
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power_state = psci_power_state_pack(state);
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err = invoke_psci_fn(fn, power_state, entry_point, 0);
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return psci_to_linux_errno(err);
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}
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static int psci_cpu_off(struct psci_power_state state)
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{
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int err;
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u32 fn, power_state;
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fn = psci_function_id[PSCI_FN_CPU_OFF];
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power_state = psci_power_state_pack(state);
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err = invoke_psci_fn(fn, power_state, 0, 0);
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return psci_to_linux_errno(err);
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}
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static int psci_cpu_on(unsigned long cpuid, unsigned long entry_point)
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{
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int err;
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u32 fn;
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fn = psci_function_id[PSCI_FN_CPU_ON];
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err = invoke_psci_fn(fn, cpuid, entry_point, 0);
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return psci_to_linux_errno(err);
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}
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static int psci_migrate(unsigned long cpuid)
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{
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int err;
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u32 fn;
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fn = psci_function_id[PSCI_FN_MIGRATE];
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err = invoke_psci_fn(fn, cpuid, 0, 0);
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return psci_to_linux_errno(err);
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}
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static const struct of_device_id psci_of_match[] __initconst = {
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{ .compatible = "arm,psci", },
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{},
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};
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static int __init psci_init(void)
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{
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struct device_node *np;
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const char *method;
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u32 id;
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np = of_find_matching_node(NULL, psci_of_match);
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if (!np)
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return 0;
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pr_info("probing function IDs from device-tree\n");
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if (of_property_read_string(np, "method", &method)) {
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pr_warning("missing \"method\" property\n");
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goto out_put_node;
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}
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if (!strcmp("hvc", method)) {
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invoke_psci_fn = __invoke_psci_fn_hvc;
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} else if (!strcmp("smc", method)) {
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invoke_psci_fn = __invoke_psci_fn_smc;
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} else {
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pr_warning("invalid \"method\" property: %s\n", method);
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goto out_put_node;
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}
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if (!of_property_read_u32(np, "cpu_suspend", &id)) {
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psci_function_id[PSCI_FN_CPU_SUSPEND] = id;
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psci_ops.cpu_suspend = psci_cpu_suspend;
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}
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if (!of_property_read_u32(np, "cpu_off", &id)) {
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psci_function_id[PSCI_FN_CPU_OFF] = id;
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psci_ops.cpu_off = psci_cpu_off;
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}
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if (!of_property_read_u32(np, "cpu_on", &id)) {
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psci_function_id[PSCI_FN_CPU_ON] = id;
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psci_ops.cpu_on = psci_cpu_on;
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}
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if (!of_property_read_u32(np, "migrate", &id)) {
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psci_function_id[PSCI_FN_MIGRATE] = id;
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psci_ops.migrate = psci_migrate;
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}
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out_put_node:
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of_node_put(np);
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return 0;
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}
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early_initcall(psci_init);
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