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Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +02001/*
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
Lorenzo Pieralisid2e5c872014-06-24 16:20:28 +010027#include "dt_idle_states.h"
28
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +020029static 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 */
62static 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,
Daniel Lezcanob82b6cc2014-11-12 16:03:50 +010070 .flags = CPUIDLE_FLAG_TIMER_STOP,
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +020071 .name = "C1",
72 .desc = "ARM little-cluster power down",
73 },
74 .state_count = 2,
75};
76
Lorenzo Pieralisid2e5c872014-06-24 16:20:28 +010077static const struct of_device_id bl_idle_state_match[] __initconst = {
78 { .compatible = "arm,idle-state",
79 .data = bl_enter_powerdown },
80 { },
81};
82
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +020083static 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,
Daniel Lezcanob82b6cc2014-11-12 16:03:50 +010091 .flags = CPUIDLE_FLAG_TIMER_STOP,
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +020092 .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 */
103static 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 */
132static 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
Juri Lellieba1c712014-08-15 15:53:14 +0100147static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int part_id)
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +0200148{
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +0200149 struct cpumask *cpumask;
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +0200150 int cpu;
151
152 cpumask = kzalloc(cpumask_size(), GFP_KERNEL);
153 if (!cpumask)
154 return -ENOMEM;
155
Juri Lellieba1c712014-08-15 15:53:14 +0100156 for_each_possible_cpu(cpu)
157 if (smp_cpuid_part(cpu) == part_id)
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +0200158 cpumask_set_cpu(cpu, cpumask);
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +0200159
160 drv->cpumask = cpumask;
161
162 return 0;
163}
164
Chander Kashyape2e54362014-07-05 06:24:34 +0900165static const struct of_device_id compatible_machine_match[] = {
166 { .compatible = "arm,vexpress,v2p-ca15_a7" },
Chander Kashyap64a3c4c2014-07-05 06:24:35 +0900167 { .compatible = "samsung,exynos5420" },
Kevin Hilman6baf6ee2014-08-12 17:11:05 -0700168 { .compatible = "samsung,exynos5800" },
Chander Kashyape2e54362014-07-05 06:24:34 +0900169 {},
170};
171
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +0200172static int __init bl_idle_init(void)
173{
174 int ret;
Chander Kashyape2e54362014-07-05 06:24:34 +0900175 struct device_node *root = of_find_node_by_path("/");
176
177 if (!root)
178 return -ENODEV;
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +0200179
180 /*
181 * Initialize the driver just for a compliant set of machines
182 */
Chander Kashyape2e54362014-07-05 06:24:34 +0900183 if (!of_match_node(compatible_machine_match, root))
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +0200184 return -ENODEV;
Sudeep Holla194fe6f2015-01-08 06:29:04 +0000185
186 if (!mcpm_is_available())
187 return -EUNATCH;
188
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +0200189 /*
190 * For now the differentiation between little and big cores
191 * is based on the part number. A7 cores are considered little
192 * cores, A15 are considered big cores. This distinction may
193 * evolve in the future with a more generic matching approach.
194 */
195 ret = bl_idle_driver_init(&bl_idle_little_driver,
196 ARM_CPU_PART_CORTEX_A7);
197 if (ret)
198 return ret;
199
200 ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15);
201 if (ret)
202 goto out_uninit_little;
203
Lorenzo Pieralisid2e5c872014-06-24 16:20:28 +0100204 /* Start at index 1, index 0 standard WFI */
205 ret = dt_init_idle_driver(&bl_idle_big_driver, bl_idle_state_match, 1);
206 if (ret < 0)
207 goto out_uninit_big;
208
209 /* Start at index 1, index 0 standard WFI */
210 ret = dt_init_idle_driver(&bl_idle_little_driver,
211 bl_idle_state_match, 1);
212 if (ret < 0)
213 goto out_uninit_big;
214
Lorenzo Pieralisi14d2c342013-06-12 17:40:01 +0200215 ret = cpuidle_register(&bl_idle_little_driver, NULL);
216 if (ret)
217 goto out_uninit_big;
218
219 ret = cpuidle_register(&bl_idle_big_driver, NULL);
220 if (ret)
221 goto out_unregister_little;
222
223 return 0;
224
225out_unregister_little:
226 cpuidle_unregister(&bl_idle_little_driver);
227out_uninit_big:
228 kfree(bl_idle_big_driver.cpumask);
229out_uninit_little:
230 kfree(bl_idle_little_driver.cpumask);
231
232 return ret;
233}
234device_initcall(bl_idle_init);