1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * ARM64 CPU idle arch support
4 *
5 * Copyright (C) 2014 ARM Ltd.
6 * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
7 */
8
9#include <linux/acpi.h>
10#include <linux/cpuidle.h>
11#include <linux/cpu_pm.h>
12#include <linux/psci.h>
13
14#ifdef CONFIG_ACPI_PROCESSOR_IDLE
15
16#include <acpi/processor.h>
17
18#define ARM64_LPI_IS_RETENTION_STATE(arch_flags) (!(arch_flags))
19
20static int psci_acpi_cpu_init_idle(unsigned int cpu)
21{
22 int i, count;
23 struct acpi_lpi_state *lpi;
24 struct acpi_processor *pr = per_cpu(processors, cpu);
25
26 if (unlikely(!pr || !pr->flags.has_lpi))
27 return -EINVAL;
28
29 /*
30 * If the PSCI cpu_suspend function hook has not been initialized
31 * idle states must not be enabled, so bail out
32 */
33 if (!psci_ops.cpu_suspend)
34 return -EOPNOTSUPP;
35
36 count = pr->power.count - 1;
37 if (count <= 0)
38 return -ENODEV;
39
40 for (i = 0; i < count; i++) {
41 u32 state;
42
43 lpi = &pr->power.lpi_states[i + 1];
44 /*
45 * Only bits[31:0] represent a PSCI power_state while
46 * bits[63:32] must be 0x0 as per ARM ACPI FFH Specification
47 */
48 state = lpi->address;
49 if (!psci_power_state_is_valid(state)) {
50 pr_warn("Invalid PSCI power state %#x\n", state);
51 return -EINVAL;
52 }
53 }
54
55 return 0;
56}
57
58int acpi_processor_ffh_lpi_probe(unsigned int cpu)
59{
60 return psci_acpi_cpu_init_idle(cpu);
61}
62
63__cpuidle int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi)
64{
65 u32 state = lpi->address;
66
67 if (ARM64_LPI_IS_RETENTION_STATE(lpi->arch_flags))
68 return CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM_RCU(psci_cpu_suspend_enter,
69 lpi->index, state);
70 else
71 return CPU_PM_CPU_IDLE_ENTER_PARAM_RCU(psci_cpu_suspend_enter,
72 lpi->index, state);
73}
74#endif
75

source code of linux/arch/arm64/kernel/cpuidle.c