1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2013 ARM/Linaro
4 *
5 * Authors: Daniel Lezcano <daniel.lezcano@linaro.org>
6 *          Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
7 *          Nicolas Pitre <nicolas.pitre@linaro.org>
8 *
9 * Maintainer: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
10 * Maintainer: Daniel Lezcano <daniel.lezcano@linaro.org>
11 */
12#include <linux/cpuidle.h>
13#include <linux/cpu_pm.h>
14#include <linux/slab.h>
15#include <linux/of.h>
16
17#include <asm/cpu.h>
18#include <asm/cputype.h>
19#include <asm/cpuidle.h>
20#include <asm/mcpm.h>
21#include <asm/smp_plat.h>
22#include <asm/suspend.h>
23
24#include "dt_idle_states.h"
25
26static int bl_enter_powerdown(struct cpuidle_device *dev,
27			      struct cpuidle_driver *drv, int idx);
28
29/*
30 * NB: Owing to current menu governor behaviour big and LITTLE
31 * index 1 states have to define exit_latency and target_residency for
32 * cluster state since, when all CPUs in a cluster hit it, the cluster
33 * can be shutdown. This means that when a single CPU enters this state
34 * the exit_latency and target_residency values are somewhat overkill.
35 * There is no notion of cluster states in the menu governor, so CPUs
36 * have to define CPU states where possibly the cluster will be shutdown
37 * depending on the state of other CPUs. idle states entry and exit happen
38 * at random times; however the cluster state provides target_residency
39 * values as if all CPUs in a cluster enter the state at once; this is
40 * somewhat optimistic and behaviour should be fixed either in the governor
41 * or in the MCPM back-ends.
42 * To make this driver 100% generic the number of states and the exit_latency
43 * target_residency values must be obtained from device tree bindings.
44 *
45 * exit_latency: refers to the TC2 vexpress test chip and depends on the
46 * current cluster operating point. It is the time it takes to get the CPU
47 * up and running when the CPU is powered up on cluster wake-up from shutdown.
48 * Current values for big and LITTLE clusters are provided for clusters
49 * running at default operating points.
50 *
51 * target_residency: it is the minimum amount of time the cluster has
52 * to be down to break even in terms of power consumption. cluster
53 * shutdown has inherent dynamic power costs (L2 writebacks to DRAM
54 * being the main factor) that depend on the current operating points.
55 * The current values for both clusters are provided for a CPU whose half
56 * of L2 lines are dirty and require cleaning to DRAM, and takes into
57 * account leakage static power values related to the vexpress TC2 testchip.
58 */
59static struct cpuidle_driver bl_idle_little_driver = {
60	.name = "little_idle",
61	.owner = THIS_MODULE,
62	.states[0] = ARM_CPUIDLE_WFI_STATE,
63	.states[1] = {
64		.enter			= bl_enter_powerdown,
65		.exit_latency		= 700,
66		.target_residency	= 2500,
67		.flags			= CPUIDLE_FLAG_TIMER_STOP |
68					  CPUIDLE_FLAG_RCU_IDLE,
69		.name			= "C1",
70		.desc			= "ARM little-cluster power down",
71	},
72	.state_count = 2,
73};
74
75static const struct of_device_id bl_idle_state_match[] __initconst = {
76	{ .compatible = "arm,idle-state",
77	  .data = bl_enter_powerdown },
78	{ },
79};
80
81static struct cpuidle_driver bl_idle_big_driver = {
82	.name = "big_idle",
83	.owner = THIS_MODULE,
84	.states[0] = ARM_CPUIDLE_WFI_STATE,
85	.states[1] = {
86		.enter			= bl_enter_powerdown,
87		.exit_latency		= 500,
88		.target_residency	= 2000,
89		.flags			= CPUIDLE_FLAG_TIMER_STOP |
90					  CPUIDLE_FLAG_RCU_IDLE,
91		.name			= "C1",
92		.desc			= "ARM big-cluster power down",
93	},
94	.state_count = 2,
95};
96
97/*
98 * notrace prevents trace shims from getting inserted where they
99 * should not. Global jumps and ldrex/strex must not be inserted
100 * in power down sequences where caches and MMU may be turned off.
101 */
102static int notrace bl_powerdown_finisher(unsigned long arg)
103{
104	/* MCPM works with HW CPU identifiers */
105	unsigned int mpidr = read_cpuid_mpidr();
106	unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
107	unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
108
109	mcpm_set_entry_vector(cpu, cluster, cpu_resume);
110	mcpm_cpu_suspend();
111
112	/* return value != 0 means failure */
113	return 1;
114}
115
116/**
117 * bl_enter_powerdown - Programs CPU to enter the specified state
118 * @dev: cpuidle device
119 * @drv: The target state to be programmed
120 * @idx: state index
121 *
122 * Called from the CPUidle framework to program the device to the
123 * specified target state selected by the governor.
124 */
125static __cpuidle int bl_enter_powerdown(struct cpuidle_device *dev,
126					struct cpuidle_driver *drv, int idx)
127{
128	cpu_pm_enter();
129	ct_cpuidle_enter();
130
131	cpu_suspend(0, bl_powerdown_finisher);
132
133	/* signals the MCPM core that CPU is out of low power state */
134	mcpm_cpu_powered_up();
135	ct_cpuidle_exit();
136
137	cpu_pm_exit();
138
139	return idx;
140}
141
142static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int part_id)
143{
144	struct cpumask *cpumask;
145	int cpu;
146
147	cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
148	if (!cpumask)
149		return -ENOMEM;
150
151	for_each_possible_cpu(cpu)
152		if (smp_cpuid_part(cpu) == part_id)
153			cpumask_set_cpu(cpu, cpumask);
154
155	drv->cpumask = cpumask;
156
157	return 0;
158}
159
160static const struct of_device_id compatible_machine_match[] = {
161	{ .compatible = "arm,vexpress,v2p-ca15_a7" },
162	{ .compatible = "google,peach" },
163	{},
164};
165
166static int __init bl_idle_init(void)
167{
168	int ret;
169	struct device_node *root = of_find_node_by_path("/");
170	const struct of_device_id *match_id;
171
172	if (!root)
173		return -ENODEV;
174
175	/*
176	 * Initialize the driver just for a compliant set of machines
177	 */
178	match_id = of_match_node(compatible_machine_match, root);
179
180	of_node_put(root);
181
182	if (!match_id)
183		return -ENODEV;
184
185	if (!mcpm_is_available())
186		return -EUNATCH;
187
188	/*
189	 * For now the differentiation between little and big cores
190	 * is based on the part number. A7 cores are considered little
191	 * cores, A15 are considered big cores. This distinction may
192	 * evolve in the future with a more generic matching approach.
193	 */
194	ret = bl_idle_driver_init(&bl_idle_little_driver,
195				  ARM_CPU_PART_CORTEX_A7);
196	if (ret)
197		return ret;
198
199	ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15);
200	if (ret)
201		goto out_uninit_little;
202
203	/* Start at index 1, index 0 standard WFI */
204	ret = dt_init_idle_driver(&bl_idle_big_driver, bl_idle_state_match, 1);
205	if (ret < 0)
206		goto out_uninit_big;
207
208	/* Start at index 1, index 0 standard WFI */
209	ret = dt_init_idle_driver(&bl_idle_little_driver,
210				  bl_idle_state_match, 1);
211	if (ret < 0)
212		goto out_uninit_big;
213
214	ret = cpuidle_register(&bl_idle_little_driver, NULL);
215	if (ret)
216		goto out_uninit_big;
217
218	ret = cpuidle_register(&bl_idle_big_driver, NULL);
219	if (ret)
220		goto out_unregister_little;
221
222	return 0;
223
224out_unregister_little:
225	cpuidle_unregister(&bl_idle_little_driver);
226out_uninit_big:
227	kfree(bl_idle_big_driver.cpumask);
228out_uninit_little:
229	kfree(bl_idle_little_driver.cpumask);
230
231	return ret;
232}
233device_initcall(bl_idle_init);
234