arch/arm64/kernel/cpuidle.c

   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
  20 static 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
  58 int 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