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 | CPUIDLE_FLAG_RCU_IDLE, |
69 | .name = "C1" , |
70 | .desc = "ARM little-cluster power down" , |
71 | }, |
72 | .state_count = 2, |
73 | }; |
74 | |
75 | static const struct of_device_id bl_idle_state_match[] __initconst = { |
76 | { .compatible = "arm,idle-state" , |
77 | .data = bl_enter_powerdown }, |
78 | { }, |
79 | }; |
80 | |
81 | static 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 | */ |
102 | static 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 | */ |
125 | static __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 | |
142 | static 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(size: 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, dstp: cpumask); |
154 | |
155 | drv->cpumask = cpumask; |
156 | |
157 | return 0; |
158 | } |
159 | |
160 | static const struct of_device_id compatible_machine_match[] = { |
161 | { .compatible = "arm,vexpress,v2p-ca15_a7" }, |
162 | { .compatible = "google,peach" }, |
163 | {}, |
164 | }; |
165 | |
166 | static int __init bl_idle_init(void) |
167 | { |
168 | int ret; |
169 | struct device_node *root = of_find_node_by_path(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(matches: compatible_machine_match, node: root); |
179 | |
180 | of_node_put(node: 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(drv: &bl_idle_little_driver, |
195 | part_id: ARM_CPU_PART_CORTEX_A7); |
196 | if (ret) |
197 | return ret; |
198 | |
199 | ret = bl_idle_driver_init(drv: &bl_idle_big_driver, part_id: 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(drv: &bl_idle_big_driver, matches: bl_idle_state_match, start_idx: 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(drv: &bl_idle_little_driver, |
210 | matches: bl_idle_state_match, start_idx: 1); |
211 | if (ret < 0) |
212 | goto out_uninit_big; |
213 | |
214 | ret = cpuidle_register(drv: &bl_idle_little_driver, NULL); |
215 | if (ret) |
216 | goto out_uninit_big; |
217 | |
218 | ret = cpuidle_register(drv: &bl_idle_big_driver, NULL); |
219 | if (ret) |
220 | goto out_unregister_little; |
221 | |
222 | return 0; |
223 | |
224 | out_unregister_little: |
225 | cpuidle_unregister(drv: &bl_idle_little_driver); |
226 | out_uninit_big: |
227 | kfree(objp: bl_idle_big_driver.cpumask); |
228 | out_uninit_little: |
229 | kfree(objp: bl_idle_little_driver.cpumask); |
230 | |
231 | return ret; |
232 | } |
233 | device_initcall(bl_idle_init); |
234 | |