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
26 static 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 */
59 static 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
74 static const struct of_device_id bl_idle_state_match[] __initconst = {
75 { .compatible = "arm,idle-state",
76 .data = bl_enter_powerdown },
77 { },
78 };
79
80 static 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 */
100 static 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 */
123 static 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
138 static 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
156 static 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
163 static 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
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);