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		.name			= "C1",
69		.desc			= "ARM little-cluster power down",
70	},
71	.state_count = 2,
72};
73
74static const struct of_device_id bl_idle_state_match[] __initconst = {
75	{ .compatible = "arm,idle-state",
76	  .data = bl_enter_powerdown },
77	{ },
78};
79
80static struct cpuidle_driver bl_idle_big_driver = {
81	.name = "big_idle",
82	.owner = THIS_MODULE,
83	.states[0] = ARM_CPUIDLE_WFI_STATE,
84	.states[1] = {
85		.enter			= bl_enter_powerdown,
86		.exit_latency		= 500,
87		.target_residency	= 2000,
88		.flags			= CPUIDLE_FLAG_TIMER_STOP,
89		.name			= "C1",
90		.desc			= "ARM big-cluster power down",
91	},
92	.state_count = 2,
93};
94
95/*
96 * notrace prevents trace shims from getting inserted where they
97 * should not. Global jumps and ldrex/strex must not be inserted
98 * in power down sequences where caches and MMU may be turned off.
99 */
100static int notrace bl_powerdown_finisher(unsigned long arg)
101{
102	/* MCPM works with HW CPU identifiers */
103	unsigned int mpidr = read_cpuid_mpidr();
104	unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
105	unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
106
107	mcpm_set_entry_vector(cpu, cluster, cpu_resume);
108	mcpm_cpu_suspend();
109
110	/* return value != 0 means failure */
111	return 1;
112}
113
114/**
115 * bl_enter_powerdown - Programs CPU to enter the specified state
116 * @dev: cpuidle device
117 * @drv: The target state to be programmed
118 * @idx: state index
119 *
120 * Called from the CPUidle framework to program the device to the
121 * specified target state selected by the governor.
122 */
123static int bl_enter_powerdown(struct cpuidle_device *dev,
124				struct cpuidle_driver *drv, int idx)
125{
126	cpu_pm_enter();
127
128	cpu_suspend(0, bl_powerdown_finisher);
129
130	/* signals the MCPM core that CPU is out of low power state */
131	mcpm_cpu_powered_up();
132
133	cpu_pm_exit();
134
135	return idx;
136}
137
138static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int part_id)
139{
140	struct cpumask *cpumask;
141	int cpu;
142
143	cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
144	if (!cpumask)
145		return -ENOMEM;
146
147	for_each_possible_cpu(cpu)
148		if (smp_cpuid_part(cpu) == part_id)
149			cpumask_set_cpu(cpu, cpumask);
150
151	drv->cpumask = cpumask;
152
153	return 0;
154}
155
156static const struct of_device_id compatible_machine_match[] = {
157	{ .compatible = "arm,vexpress,v2p-ca15_a7" },
158	{ .compatible = "samsung,exynos5420" },
159	{ .compatible = "samsung,exynos5800" },
160	{},
161};
162
163static int __init bl_idle_init(void)
164{
165	int ret;
166	struct device_node *root = of_find_node_by_path("/");
167	const struct of_device_id *match_id;
168
169	if (!root)
170		return -ENODEV;
171
172	/*
173	 * Initialize the driver just for a compliant set of machines
174	 */
175	match_id = of_match_node(compatible_machine_match, root);
176
177	of_node_put(root);
178
179	if (!match_id)
180		return -ENODEV;
181
182	if (!mcpm_is_available())
183		return -EUNATCH;
184
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
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
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
221out_unregister_little:
222	cpuidle_unregister(&bl_idle_little_driver);
223out_uninit_big:
224	kfree(bl_idle_big_driver.cpumask);
225out_uninit_little:
226	kfree(bl_idle_little_driver.cpumask);
227
228	return ret;
229}
230device_initcall(bl_idle_init);
231