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/of.h>
  13 #include <linux/of_device.h>
  14 #include <linux/psci.h>
  15
  16 #ifdef CONFIG_ACPI
  17
  18 #include <acpi/processor.h>
  19
  20 #define ARM64_LPI_IS_RETENTION_STATE(arch_flags) (!(arch_flags))
  21
  22 static int psci_acpi_cpu_init_idle(unsigned int cpu)
  23 {
  24         int i, count;
  25         struct acpi_lpi_state *lpi;
  26         struct acpi_processor *pr = per_cpu(processors, cpu);
  27
  28         if (unlikely(!pr || !pr->flags.has_lpi))
  29                 return -EINVAL;
  30
  31         /*
  32          * If the PSCI cpu_suspend function hook has not been initialized
  33          * idle states must not be enabled, so bail out
  34          */
  35         if (!psci_ops.cpu_suspend)
  36                 return -EOPNOTSUPP;
  37
  38         count = pr->power.count - 1;
  39         if (count <= 0)
  40                 return -ENODEV;
  41
  42         for (i = 0; i < count; i++) {
  43                 u32 state;
  44
  45                 lpi = &pr->power.lpi_states[i + 1];
  46                 /*
  47                  * Only bits[31:0] represent a PSCI power_state while
  48                  * bits[63:32] must be 0x0 as per ARM ACPI FFH Specification
  49                  */
  50                 state = lpi->address;
  51                 if (!psci_power_state_is_valid(state)) {
  52                         pr_warn("Invalid PSCI power state %#x\n", state);
  53                         return -EINVAL;
  54                 }
  55         }
  56
  57         return 0;
  58 }
  59
  60 int acpi_processor_ffh_lpi_probe(unsigned int cpu)
  61 {
  62         return psci_acpi_cpu_init_idle(cpu);
  63 }
  64
  65 int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi)
  66 {
  67         u32 state = lpi->address;
  68
  69         if (ARM64_LPI_IS_RETENTION_STATE(lpi->arch_flags))
  70                 return CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM(psci_cpu_suspend_enter,
  71                                                 lpi->index, state);
  72         else
  73                 return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter,
  74                                              lpi->index, state);
  75 }
  76 #endif