234 lines
6.7 KiB
C
234 lines
6.7 KiB
C
/*
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* Copyright (c) 2013 ARM/Linaro
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*
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* Authors: Daniel Lezcano <daniel.lezcano@linaro.org>
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* Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
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* Nicolas Pitre <nicolas.pitre@linaro.org>
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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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* Maintainer: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
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* Maintainer: Daniel Lezcano <daniel.lezcano@linaro.org>
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*/
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#include <linux/cpuidle.h>
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#include <linux/cpu_pm.h>
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#include <linux/slab.h>
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#include <linux/of.h>
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#include <asm/cpu.h>
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#include <asm/cputype.h>
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#include <asm/cpuidle.h>
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#include <asm/mcpm.h>
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#include <asm/smp_plat.h>
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#include <asm/suspend.h>
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#include "dt_idle_states.h"
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static int bl_enter_powerdown(struct cpuidle_device *dev,
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struct cpuidle_driver *drv, int idx);
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/*
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* NB: Owing to current menu governor behaviour big and LITTLE
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* index 1 states have to define exit_latency and target_residency for
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* cluster state since, when all CPUs in a cluster hit it, the cluster
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* can be shutdown. This means that when a single CPU enters this state
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* the exit_latency and target_residency values are somewhat overkill.
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* There is no notion of cluster states in the menu governor, so CPUs
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* have to define CPU states where possibly the cluster will be shutdown
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* depending on the state of other CPUs. idle states entry and exit happen
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* at random times; however the cluster state provides target_residency
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* values as if all CPUs in a cluster enter the state at once; this is
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* somewhat optimistic and behaviour should be fixed either in the governor
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* or in the MCPM back-ends.
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* To make this driver 100% generic the number of states and the exit_latency
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* target_residency values must be obtained from device tree bindings.
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*
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* exit_latency: refers to the TC2 vexpress test chip and depends on the
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* current cluster operating point. It is the time it takes to get the CPU
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* up and running when the CPU is powered up on cluster wake-up from shutdown.
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* Current values for big and LITTLE clusters are provided for clusters
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* running at default operating points.
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*
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* target_residency: it is the minimum amount of time the cluster has
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* to be down to break even in terms of power consumption. cluster
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* shutdown has inherent dynamic power costs (L2 writebacks to DRAM
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* being the main factor) that depend on the current operating points.
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* The current values for both clusters are provided for a CPU whose half
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* of L2 lines are dirty and require cleaning to DRAM, and takes into
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* account leakage static power values related to the vexpress TC2 testchip.
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*/
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static struct cpuidle_driver bl_idle_little_driver = {
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.name = "little_idle",
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.owner = THIS_MODULE,
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.states[0] = ARM_CPUIDLE_WFI_STATE,
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.states[1] = {
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.enter = bl_enter_powerdown,
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.exit_latency = 700,
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.target_residency = 2500,
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.flags = CPUIDLE_FLAG_TIMER_STOP,
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.name = "C1",
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.desc = "ARM little-cluster power down",
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},
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.state_count = 2,
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};
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static const struct of_device_id bl_idle_state_match[] __initconst = {
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{ .compatible = "arm,idle-state",
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.data = bl_enter_powerdown },
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{ },
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};
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static struct cpuidle_driver bl_idle_big_driver = {
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.name = "big_idle",
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.owner = THIS_MODULE,
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.states[0] = ARM_CPUIDLE_WFI_STATE,
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.states[1] = {
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.enter = bl_enter_powerdown,
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.exit_latency = 500,
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.target_residency = 2000,
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.flags = CPUIDLE_FLAG_TIMER_STOP,
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.name = "C1",
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.desc = "ARM big-cluster power down",
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},
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.state_count = 2,
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};
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/*
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* notrace prevents trace shims from getting inserted where they
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* should not. Global jumps and ldrex/strex must not be inserted
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* in power down sequences where caches and MMU may be turned off.
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*/
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static int notrace bl_powerdown_finisher(unsigned long arg)
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{
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/* MCPM works with HW CPU identifiers */
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unsigned int mpidr = read_cpuid_mpidr();
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unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
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unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
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mcpm_set_entry_vector(cpu, cluster, cpu_resume);
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mcpm_cpu_suspend();
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/* return value != 0 means failure */
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return 1;
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}
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/**
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* bl_enter_powerdown - Programs CPU to enter the specified state
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* @dev: cpuidle device
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* @drv: The target state to be programmed
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* @idx: state index
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*
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* Called from the CPUidle framework to program the device to the
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* specified target state selected by the governor.
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*/
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static int bl_enter_powerdown(struct cpuidle_device *dev,
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struct cpuidle_driver *drv, int idx)
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{
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cpu_pm_enter();
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cpu_suspend(0, bl_powerdown_finisher);
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/* signals the MCPM core that CPU is out of low power state */
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mcpm_cpu_powered_up();
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cpu_pm_exit();
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return idx;
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}
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static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int part_id)
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{
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struct cpumask *cpumask;
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int cpu;
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cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
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if (!cpumask)
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return -ENOMEM;
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for_each_possible_cpu(cpu)
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if (smp_cpuid_part(cpu) == part_id)
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cpumask_set_cpu(cpu, cpumask);
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drv->cpumask = cpumask;
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return 0;
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}
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static const struct of_device_id compatible_machine_match[] = {
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{ .compatible = "arm,vexpress,v2p-ca15_a7" },
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{ .compatible = "samsung,exynos5420" },
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{ .compatible = "samsung,exynos5800" },
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{},
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};
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static int __init bl_idle_init(void)
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{
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int ret;
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struct device_node *root = of_find_node_by_path("/");
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const struct of_device_id *match_id;
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if (!root)
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return -ENODEV;
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/*
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* Initialize the driver just for a compliant set of machines
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*/
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match_id = of_match_node(compatible_machine_match, root);
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of_node_put(root);
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if (!match_id)
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return -ENODEV;
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if (!mcpm_is_available())
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return -EUNATCH;
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/*
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* For now the differentiation between little and big cores
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* is based on the part number. A7 cores are considered little
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* cores, A15 are considered big cores. This distinction may
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* evolve in the future with a more generic matching approach.
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*/
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ret = bl_idle_driver_init(&bl_idle_little_driver,
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ARM_CPU_PART_CORTEX_A7);
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if (ret)
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return ret;
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ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15);
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if (ret)
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goto out_uninit_little;
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/* Start at index 1, index 0 standard WFI */
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ret = dt_init_idle_driver(&bl_idle_big_driver, bl_idle_state_match, 1);
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if (ret < 0)
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goto out_uninit_big;
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/* Start at index 1, index 0 standard WFI */
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ret = dt_init_idle_driver(&bl_idle_little_driver,
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bl_idle_state_match, 1);
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if (ret < 0)
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goto out_uninit_big;
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ret = cpuidle_register(&bl_idle_little_driver, NULL);
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if (ret)
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goto out_uninit_big;
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ret = cpuidle_register(&bl_idle_big_driver, NULL);
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if (ret)
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goto out_unregister_little;
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return 0;
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out_unregister_little:
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cpuidle_unregister(&bl_idle_little_driver);
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out_uninit_big:
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kfree(bl_idle_big_driver.cpumask);
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out_uninit_little:
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kfree(bl_idle_little_driver.cpumask);
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return ret;
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}
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device_initcall(bl_idle_init);
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