[deliverable/linux.git] / drivers / cpuidle / cpuidle-big_little.c

/*
 * Copyright (c) 2013 ARM/Linaro
 *
 * Authors: Daniel Lezcano <daniel.lezcano@linaro.org>
 *          Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
 *          Nicolas Pitre <nicolas.pitre@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Maintainer: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
 * Maintainer: Daniel Lezcano <daniel.lezcano@linaro.org>
 */
#include <linux/cpuidle.h>
#include <linux/cpu_pm.h>
#include <linux/slab.h>
#include <linux/of.h>

#include <asm/cpu.h>
#include <asm/cputype.h>
#include <asm/cpuidle.h>
#include <asm/mcpm.h>
#include <asm/smp_plat.h>
#include <asm/suspend.h>

#include "dt_idle_states.h"

static int bl_enter_powerdown(struct cpuidle_device *dev,
			      struct cpuidle_driver *drv, int idx);

/*
 * NB: Owing to current menu governor behaviour big and LITTLE
 * index 1 states have to define exit_latency and target_residency for
 * cluster state since, when all CPUs in a cluster hit it, the cluster
 * can be shutdown. This means that when a single CPU enters this state
 * the exit_latency and target_residency values are somewhat overkill.
 * There is no notion of cluster states in the menu governor, so CPUs
 * have to define CPU states where possibly the cluster will be shutdown
 * depending on the state of other CPUs. idle states entry and exit happen
 * at random times; however the cluster state provides target_residency
 * values as if all CPUs in a cluster enter the state at once; this is
 * somewhat optimistic and behaviour should be fixed either in the governor
 * or in the MCPM back-ends.
 * To make this driver 100% generic the number of states and the exit_latency
 * target_residency values must be obtained from device tree bindings.
 *
 * exit_latency: refers to the TC2 vexpress test chip and depends on the
 * current cluster operating point. It is the time it takes to get the CPU
 * up and running when the CPU is powered up on cluster wake-up from shutdown.
 * Current values for big and LITTLE clusters are provided for clusters
 * running at default operating points.
 *
 * target_residency: it is the minimum amount of time the cluster has
 * to be down to break even in terms of power consumption. cluster
 * shutdown has inherent dynamic power costs (L2 writebacks to DRAM
 * being the main factor) that depend on the current operating points.
 * The current values for both clusters are provided for a CPU whose half
 * of L2 lines are dirty and require cleaning to DRAM, and takes into
 * account leakage static power values related to the vexpress TC2 testchip.
 */
static struct cpuidle_driver bl_idle_little_driver = {
	.name = "little_idle",
	.owner = THIS_MODULE,
	.states[0] = ARM_CPUIDLE_WFI_STATE,
	.states[1] = {
		.enter			= bl_enter_powerdown,
		.exit_latency		= 700,
		.target_residency	= 2500,
		.flags			= CPUIDLE_FLAG_TIMER_STOP,
		.name			= "C1",
		.desc			= "ARM little-cluster power down",
	},
	.state_count = 2,
};

static const struct of_device_id bl_idle_state_match[] __initconst = {
	{ .compatible = "arm,idle-state",
	  .data = bl_enter_powerdown },
	{ },
};

static struct cpuidle_driver bl_idle_big_driver = {
	.name = "big_idle",
	.owner = THIS_MODULE,
	.states[0] = ARM_CPUIDLE_WFI_STATE,
	.states[1] = {
		.enter			= bl_enter_powerdown,
		.exit_latency		= 500,
		.target_residency	= 2000,
		.flags			= CPUIDLE_FLAG_TIMER_STOP,
		.name			= "C1",
		.desc			= "ARM big-cluster power down",
	},
	.state_count = 2,
};

/*
 * notrace prevents trace shims from getting inserted where they
 * should not. Global jumps and ldrex/strex must not be inserted
 * in power down sequences where caches and MMU may be turned off.
 */
static int notrace bl_powerdown_finisher(unsigned long arg)
{
	/* MCPM works with HW CPU identifiers */
	unsigned int mpidr = read_cpuid_mpidr();
	unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
	unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);

	mcpm_set_entry_vector(cpu, cluster, cpu_resume);

	/*
	 * Residency value passed to mcpm_cpu_suspend back-end
	 * has to be given clear semantics. Set to 0 as a
	 * temporary value.
	 */
	mcpm_cpu_suspend(0);

	/* return value != 0 means failure */
	return 1;
}

/**
 * bl_enter_powerdown - Programs CPU to enter the specified state
 * @dev: cpuidle device
 * @drv: The target state to be programmed
 * @idx: state index
 *
 * Called from the CPUidle framework to program the device to the
 * specified target state selected by the governor.
 */
static int bl_enter_powerdown(struct cpuidle_device *dev,
				struct cpuidle_driver *drv, int idx)
{
	cpu_pm_enter();

	cpu_suspend(0, bl_powerdown_finisher);

	/* signals the MCPM core that CPU is out of low power state */
	mcpm_cpu_powered_up();

	cpu_pm_exit();

	return idx;
}

static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int part_id)
{
	struct cpumask *cpumask;
	int cpu;

	cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
	if (!cpumask)
		return -ENOMEM;

	for_each_possible_cpu(cpu)
		if (smp_cpuid_part(cpu) == part_id)
			cpumask_set_cpu(cpu, cpumask);

	drv->cpumask = cpumask;

	return 0;
}

static const struct of_device_id compatible_machine_match[] = {
	{ .compatible = "arm,vexpress,v2p-ca15_a7" },
	{ .compatible = "samsung,exynos5420" },
	{ .compatible = "samsung,exynos5800" },
	{},
};

static int __init bl_idle_init(void)
{
	int ret;
	struct device_node *root = of_find_node_by_path("/");

	if (!root)
		return -ENODEV;

	/*
	 * Initialize the driver just for a compliant set of machines
	 */
	if (!of_match_node(compatible_machine_match, root))
		return -ENODEV;
	/*
	 * For now the differentiation between little and big cores
	 * is based on the part number. A7 cores are considered little
	 * cores, A15 are considered big cores. This distinction may
	 * evolve in the future with a more generic matching approach.
	 */
	ret = bl_idle_driver_init(&bl_idle_little_driver,
				  ARM_CPU_PART_CORTEX_A7);
	if (ret)
		return ret;

	ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15);
	if (ret)
		goto out_uninit_little;

	/* Start at index 1, index 0 standard WFI */
	ret = dt_init_idle_driver(&bl_idle_big_driver, bl_idle_state_match, 1);
	if (ret < 0)
		goto out_uninit_big;

	/* Start at index 1, index 0 standard WFI */
	ret = dt_init_idle_driver(&bl_idle_little_driver,
				  bl_idle_state_match, 1);
	if (ret < 0)
		goto out_uninit_big;

	ret = cpuidle_register(&bl_idle_little_driver, NULL);
	if (ret)
		goto out_uninit_big;

	ret = cpuidle_register(&bl_idle_big_driver, NULL);
	if (ret)
		goto out_unregister_little;

	return 0;

out_unregister_little:
	cpuidle_unregister(&bl_idle_little_driver);
out_uninit_big:
	kfree(bl_idle_big_driver.cpumask);
out_uninit_little:
	kfree(bl_idle_little_driver.cpumask);

	return ret;
}
device_initcall(bl_idle_init);
Commit	Line	Data
14d2c34c LP	1	/*
	2	* Copyright (c) 2013 ARM/Linaro
	3	*
	4	* Authors: Daniel Lezcano <daniel.lezcano@linaro.org>
	5	* Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
	6	* Nicolas Pitre <nicolas.pitre@linaro.org>
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License version 2 as
	10	* published by the Free Software Foundation.
	11	*
	12	* Maintainer: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
	13	* Maintainer: Daniel Lezcano <daniel.lezcano@linaro.org>
	14	*/
	15	#include <linux/cpuidle.h>
	16	#include <linux/cpu_pm.h>
	17	#include <linux/slab.h>
	18	#include <linux/of.h>
	19
	20	#include <asm/cpu.h>
	21	#include <asm/cputype.h>
	22	#include <asm/cpuidle.h>
	23	#include <asm/mcpm.h>
	24	#include <asm/smp_plat.h>
	25	#include <asm/suspend.h>
	26
d2e5c871 LP	27	#include "dt_idle_states.h"
d2e5c871 LP	28
14d2c34c LP	29	static int bl_enter_powerdown(struct cpuidle_device *dev,
	30	struct cpuidle_driver *drv, int idx);
	31
	32	/*
	33	* NB: Owing to current menu governor behaviour big and LITTLE
	34	* index 1 states have to define exit_latency and target_residency for
	35	* cluster state since, when all CPUs in a cluster hit it, the cluster
	36	* can be shutdown. This means that when a single CPU enters this state
	37	* the exit_latency and target_residency values are somewhat overkill.
	38	* There is no notion of cluster states in the menu governor, so CPUs
	39	* have to define CPU states where possibly the cluster will be shutdown
	40	* depending on the state of other CPUs. idle states entry and exit happen
	41	* at random times; however the cluster state provides target_residency
	42	* values as if all CPUs in a cluster enter the state at once; this is
	43	* somewhat optimistic and behaviour should be fixed either in the governor
	44	* or in the MCPM back-ends.
	45	* To make this driver 100% generic the number of states and the exit_latency
	46	* target_residency values must be obtained from device tree bindings.
	47	*
	48	* exit_latency: refers to the TC2 vexpress test chip and depends on the
	49	* current cluster operating point. It is the time it takes to get the CPU
	50	* up and running when the CPU is powered up on cluster wake-up from shutdown.
	51	* Current values for big and LITTLE clusters are provided for clusters
	52	* running at default operating points.
	53	*
	54	* target_residency: it is the minimum amount of time the cluster has
	55	* to be down to break even in terms of power consumption. cluster
	56	* shutdown has inherent dynamic power costs (L2 writebacks to DRAM
	57	* being the main factor) that depend on the current operating points.
	58	* The current values for both clusters are provided for a CPU whose half
	59	* of L2 lines are dirty and require cleaning to DRAM, and takes into
	60	* account leakage static power values related to the vexpress TC2 testchip.
	61	*/
	62	static struct cpuidle_driver bl_idle_little_driver = {
	63	.name = "little_idle",
	64	.owner = THIS_MODULE,
	65	.states[0] = ARM_CPUIDLE_WFI_STATE,
	66	.states[1] = {
	67	.enter = bl_enter_powerdown,
	68	.exit_latency = 700,
	69	.target_residency = 2500,
b82b6cca	70	.flags = CPUIDLE_FLAG_TIMER_STOP,
14d2c34c LP	71	.name = "C1",
	72	.desc = "ARM little-cluster power down",
	73	},
	74	.state_count = 2,
	75	};
	76
d2e5c871 LP	77	static const struct of_device_id bl_idle_state_match[] __initconst = {
	78	{ .compatible = "arm,idle-state",
	79	.data = bl_enter_powerdown },
	80	{ },
	81	};
	82
14d2c34c LP	83	static struct cpuidle_driver bl_idle_big_driver = {
	84	.name = "big_idle",
	85	.owner = THIS_MODULE,
	86	.states[0] = ARM_CPUIDLE_WFI_STATE,
	87	.states[1] = {
	88	.enter = bl_enter_powerdown,
	89	.exit_latency = 500,
	90	.target_residency = 2000,
b82b6cca	91	.flags = CPUIDLE_FLAG_TIMER_STOP,
14d2c34c LP	92	.name = "C1",
	93	.desc = "ARM big-cluster power down",
	94	},
	95	.state_count = 2,
	96	};
	97
	98	/*
	99	* notrace prevents trace shims from getting inserted where they
	100	* should not. Global jumps and ldrex/strex must not be inserted
	101	* in power down sequences where caches and MMU may be turned off.
	102	*/
	103	static int notrace bl_powerdown_finisher(unsigned long arg)
	104	{
	105	/* MCPM works with HW CPU identifiers */
	106	unsigned int mpidr = read_cpuid_mpidr();
	107	unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
	108	unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
	109
	110	mcpm_set_entry_vector(cpu, cluster, cpu_resume);
	111
	112	/*
	113	* Residency value passed to mcpm_cpu_suspend back-end
	114	* has to be given clear semantics. Set to 0 as a
	115	* temporary value.
	116	*/
	117	mcpm_cpu_suspend(0);
	118
	119	/* return value != 0 means failure */
	120	return 1;
	121	}
	122
	123	/**
	124	* bl_enter_powerdown - Programs CPU to enter the specified state
	125	* @dev: cpuidle device
	126	* @drv: The target state to be programmed
	127	* @idx: state index
	128	*
	129	* Called from the CPUidle framework to program the device to the
	130	* specified target state selected by the governor.
	131	*/
	132	static int bl_enter_powerdown(struct cpuidle_device *dev,
	133	struct cpuidle_driver *drv, int idx)
	134	{
	135	cpu_pm_enter();
	136
	137	cpu_suspend(0, bl_powerdown_finisher);
	138
	139	/* signals the MCPM core that CPU is out of low power state */
	140	mcpm_cpu_powered_up();
	141
	142	cpu_pm_exit();
	143
	144	return idx;
	145	}
	146
eba1c718	147	static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int part_id)
14d2c34c	148	{
14d2c34c	149	struct cpumask *cpumask;
14d2c34c LP	150	int cpu;
	151
	152	cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
	153	if (!cpumask)
	154	return -ENOMEM;
	155
eba1c718 JL	156	for_each_possible_cpu(cpu)
eba1c718 JL	157	if (smp_cpuid_part(cpu) == part_id)
14d2c34c	158	cpumask_set_cpu(cpu, cpumask);
14d2c34c LP	159
	160	drv->cpumask = cpumask;
	161
	162	return 0;
	163	}
	164
e2e54362 CK	165	static const struct of_device_id compatible_machine_match[] = {
e2e54362 CK	166	{ .compatible = "arm,vexpress,v2p-ca15_a7" },
64a3c4ca	167	{ .compatible = "samsung,exynos5420" },
6baf6ee5	168	{ .compatible = "samsung,exynos5800" },
e2e54362 CK	169	{},
	170	};
	171
14d2c34c LP	172	static int __init bl_idle_init(void)
	173	{
	174	int ret;
e2e54362 CK	175	struct device_node *root = of_find_node_by_path("/");
	176
	177	if (!root)
	178	return -ENODEV;
14d2c34c LP	179
	180	/*
	181	* Initialize the driver just for a compliant set of machines
	182	*/
e2e54362	183	if (!of_match_node(compatible_machine_match, root))
14d2c34c LP	184	return -ENODEV;
	185	/*
	186	* For now the differentiation between little and big cores
	187	* is based on the part number. A7 cores are considered little
	188	* cores, A15 are considered big cores. This distinction may
	189	* evolve in the future with a more generic matching approach.
	190	*/
	191	ret = bl_idle_driver_init(&bl_idle_little_driver,
	192	ARM_CPU_PART_CORTEX_A7);
	193	if (ret)
	194	return ret;
	195
	196	ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15);
	197	if (ret)
	198	goto out_uninit_little;
	199
d2e5c871 LP	200	/* Start at index 1, index 0 standard WFI */
	201	ret = dt_init_idle_driver(&bl_idle_big_driver, bl_idle_state_match, 1);
	202	if (ret < 0)
	203	goto out_uninit_big;
	204
	205	/* Start at index 1, index 0 standard WFI */
	206	ret = dt_init_idle_driver(&bl_idle_little_driver,
	207	bl_idle_state_match, 1);
	208	if (ret < 0)
	209	goto out_uninit_big;
	210
14d2c34c LP	211	ret = cpuidle_register(&bl_idle_little_driver, NULL);
	212	if (ret)
	213	goto out_uninit_big;
	214
	215	ret = cpuidle_register(&bl_idle_big_driver, NULL);
	216	if (ret)
	217	goto out_unregister_little;
	218
	219	return 0;
	220
	221	out_unregister_little:
	222	cpuidle_unregister(&bl_idle_little_driver);
	223	out_uninit_big:
	224	kfree(bl_idle_big_driver.cpumask);
	225	out_uninit_little:
	226	kfree(bl_idle_little_driver.cpumask);
	227
	228	return ret;
	229	}
	230	device_initcall(bl_idle_init);