1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * ARM/ARM64 generic CPU idle driver.
  4 *
  5 * Copyright (C) 2014 ARM Ltd.
  6 * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
  7 */
  8
  9#define pr_fmt(fmt) "CPUidle arm: " fmt
 10
 11#include <linux/cpu_cooling.h>
 12#include <linux/cpuidle.h>
 13#include <linux/cpumask.h>
 14#include <linux/cpu_pm.h>
 15#include <linux/kernel.h>
 16#include <linux/module.h>
 17#include <linux/of.h>
 18#include <linux/slab.h>
 19
 20#include <asm/cpuidle.h>
 21
 22#include "dt_idle_states.h"
 23
 24/*
 25 * arm_enter_idle_state - Programs CPU to enter the specified state
 26 *
 27 * dev: cpuidle device
 28 * drv: cpuidle driver
 29 * idx: state index
 30 *
 31 * Called from the CPUidle framework to program the device to the
 32 * specified target state selected by the governor.
 33 */
 34static __cpuidle int arm_enter_idle_state(struct cpuidle_device *dev,
 35					  struct cpuidle_driver *drv, int idx)
 36{
 37	/*
 38	 * Pass idle state index to arm_cpuidle_suspend which in turn
 39	 * will call the CPU ops suspend protocol with idle index as a
 40	 * parameter.
 41	 */
 42	return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, idx);
 43}
 44
 45static struct cpuidle_driver arm_idle_driver __initdata = {
 46	.name = "arm_idle",
 47	.owner = THIS_MODULE,
 48	/*
 49	 * State at index 0 is standby wfi and considered standard
 50	 * on all ARM platforms. If in some platforms simple wfi
 51	 * can't be used as "state 0", DT bindings must be implemented
 52	 * to work around this issue and allow installing a special
 53	 * handler for idle state index 0.
 54	 */
 55	.states[0] = {
 56		.enter                  = arm_enter_idle_state,
 57		.exit_latency           = 1,
 58		.target_residency       = 1,
 59		.power_usage		= UINT_MAX,
 60		.name                   = "WFI",
 61		.desc                   = "ARM WFI",
 62	}
 63};
 64
 65static const struct of_device_id arm_idle_state_match[] __initconst = {
 66	{ .compatible = "arm,idle-state",
 67	  .data = arm_enter_idle_state },
 68	{ },
 69};
 70
 71/*
 72 * arm_idle_init_cpu
 73 *
 74 * Registers the arm specific cpuidle driver with the cpuidle
 75 * framework. It relies on core code to parse the idle states
 76 * and initialize them using driver data structures accordingly.
 77 */
 78static int __init arm_idle_init_cpu(int cpu)
 79{
 80	int ret;
 81	struct cpuidle_driver *drv;
 82
 83	drv = kmemdup(&arm_idle_driver, sizeof(*drv), GFP_KERNEL);
 84	if (!drv)
 85		return -ENOMEM;
 86
 87	drv->cpumask = (struct cpumask *)cpumask_of(cpu);
 88
 89	/*
 90	 * Initialize idle states data, starting at index 1.  This
 91	 * driver is DT only, if no DT idle states are detected (ret
 92	 * == 0) let the driver initialization fail accordingly since
 93	 * there is no reason to initialize the idle driver if only
 94	 * wfi is supported.
 95	 */
 96	ret = dt_init_idle_driver(drv, arm_idle_state_match, 1);
 97	if (ret <= 0) {
 98		ret = ret ? : -ENODEV;
 99		goto out_kfree_drv;
100	}
101
102	/*
103	 * Call arch CPU operations in order to initialize
104	 * idle states suspend back-end specific data
105	 */
106	ret = arm_cpuidle_init(cpu);
107
108	/*
109	 * Allow the initialization to continue for other CPUs, if the
110	 * reported failure is a HW misconfiguration/breakage (-ENXIO).
111	 *
112	 * Some platforms do not support idle operations
113	 * (arm_cpuidle_init() returning -EOPNOTSUPP), we should
114	 * not flag this case as an error, it is a valid
115	 * configuration.
116	 */
117	if (ret) {
118		if (ret != -EOPNOTSUPP)
119			pr_err("CPU %d failed to init idle CPU ops\n", cpu);
120		ret = ret == -ENXIO ? 0 : ret;
121		goto out_kfree_drv;
122	}
123
124	ret = cpuidle_register(drv, NULL);
125	if (ret)
126		goto out_kfree_drv;
127
128	cpuidle_cooling_register(drv);
129
130	return 0;
131
132out_kfree_drv:
133	kfree(drv);
134	return ret;
135}
136
137/*
138 * arm_idle_init - Initializes arm cpuidle driver
139 *
140 * Initializes arm cpuidle driver for all CPUs, if any CPU fails
141 * to register cpuidle driver then rollback to cancel all CPUs
142 * registeration.
143 */
144static int __init arm_idle_init(void)
145{
146	int cpu, ret;
147	struct cpuidle_driver *drv;
148	struct cpuidle_device *dev;
149
150	for_each_possible_cpu(cpu) {
151		ret = arm_idle_init_cpu(cpu);
152		if (ret)
153			goto out_fail;
154	}
155
156	return 0;
157
158out_fail:
159	while (--cpu >= 0) {
160		dev = per_cpu(cpuidle_devices, cpu);
161		drv = cpuidle_get_cpu_driver(dev);
162		cpuidle_unregister(drv);
163		kfree(drv);
164	}
165
166	return ret;
167}
168device_initcall(arm_idle_init);