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14d2c34c LP |
1 | /* |
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 | ||
27 | static int bl_enter_powerdown(struct cpuidle_device *dev, | |
28 | struct cpuidle_driver *drv, int idx); | |
29 | ||
30 | /* | |
31 | * NB: Owing to current menu governor behaviour big and LITTLE | |
32 | * index 1 states have to define exit_latency and target_residency for | |
33 | * cluster state since, when all CPUs in a cluster hit it, the cluster | |
34 | * can be shutdown. This means that when a single CPU enters this state | |
35 | * the exit_latency and target_residency values are somewhat overkill. | |
36 | * There is no notion of cluster states in the menu governor, so CPUs | |
37 | * have to define CPU states where possibly the cluster will be shutdown | |
38 | * depending on the state of other CPUs. idle states entry and exit happen | |
39 | * at random times; however the cluster state provides target_residency | |
40 | * values as if all CPUs in a cluster enter the state at once; this is | |
41 | * somewhat optimistic and behaviour should be fixed either in the governor | |
42 | * or in the MCPM back-ends. | |
43 | * To make this driver 100% generic the number of states and the exit_latency | |
44 | * target_residency values must be obtained from device tree bindings. | |
45 | * | |
46 | * exit_latency: refers to the TC2 vexpress test chip and depends on the | |
47 | * current cluster operating point. It is the time it takes to get the CPU | |
48 | * up and running when the CPU is powered up on cluster wake-up from shutdown. | |
49 | * Current values for big and LITTLE clusters are provided for clusters | |
50 | * running at default operating points. | |
51 | * | |
52 | * target_residency: it is the minimum amount of time the cluster has | |
53 | * to be down to break even in terms of power consumption. cluster | |
54 | * shutdown has inherent dynamic power costs (L2 writebacks to DRAM | |
55 | * being the main factor) that depend on the current operating points. | |
56 | * The current values for both clusters are provided for a CPU whose half | |
57 | * of L2 lines are dirty and require cleaning to DRAM, and takes into | |
58 | * account leakage static power values related to the vexpress TC2 testchip. | |
59 | */ | |
60 | static struct cpuidle_driver bl_idle_little_driver = { | |
61 | .name = "little_idle", | |
62 | .owner = THIS_MODULE, | |
63 | .states[0] = ARM_CPUIDLE_WFI_STATE, | |
64 | .states[1] = { | |
65 | .enter = bl_enter_powerdown, | |
66 | .exit_latency = 700, | |
67 | .target_residency = 2500, | |
68 | .flags = CPUIDLE_FLAG_TIME_VALID | | |
69 | CPUIDLE_FLAG_TIMER_STOP, | |
70 | .name = "C1", | |
71 | .desc = "ARM little-cluster power down", | |
72 | }, | |
73 | .state_count = 2, | |
74 | }; | |
75 | ||
76 | static struct cpuidle_driver bl_idle_big_driver = { | |
77 | .name = "big_idle", | |
78 | .owner = THIS_MODULE, | |
79 | .states[0] = ARM_CPUIDLE_WFI_STATE, | |
80 | .states[1] = { | |
81 | .enter = bl_enter_powerdown, | |
82 | .exit_latency = 500, | |
83 | .target_residency = 2000, | |
84 | .flags = CPUIDLE_FLAG_TIME_VALID | | |
85 | CPUIDLE_FLAG_TIMER_STOP, | |
86 | .name = "C1", | |
87 | .desc = "ARM big-cluster power down", | |
88 | }, | |
89 | .state_count = 2, | |
90 | }; | |
91 | ||
92 | /* | |
93 | * notrace prevents trace shims from getting inserted where they | |
94 | * should not. Global jumps and ldrex/strex must not be inserted | |
95 | * in power down sequences where caches and MMU may be turned off. | |
96 | */ | |
97 | static int notrace bl_powerdown_finisher(unsigned long arg) | |
98 | { | |
99 | /* MCPM works with HW CPU identifiers */ | |
100 | unsigned int mpidr = read_cpuid_mpidr(); | |
101 | unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); | |
102 | unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); | |
103 | ||
104 | mcpm_set_entry_vector(cpu, cluster, cpu_resume); | |
105 | ||
106 | /* | |
107 | * Residency value passed to mcpm_cpu_suspend back-end | |
108 | * has to be given clear semantics. Set to 0 as a | |
109 | * temporary value. | |
110 | */ | |
111 | mcpm_cpu_suspend(0); | |
112 | ||
113 | /* return value != 0 means failure */ | |
114 | return 1; | |
115 | } | |
116 | ||
117 | /** | |
118 | * bl_enter_powerdown - Programs CPU to enter the specified state | |
119 | * @dev: cpuidle device | |
120 | * @drv: The target state to be programmed | |
121 | * @idx: state index | |
122 | * | |
123 | * Called from the CPUidle framework to program the device to the | |
124 | * specified target state selected by the governor. | |
125 | */ | |
126 | static int bl_enter_powerdown(struct cpuidle_device *dev, | |
127 | struct cpuidle_driver *drv, int idx) | |
128 | { | |
129 | cpu_pm_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 | ||
136 | cpu_pm_exit(); | |
137 | ||
138 | return idx; | |
139 | } | |
140 | ||
141 | static int __init bl_idle_driver_init(struct cpuidle_driver *drv, int cpu_id) | |
142 | { | |
143 | struct cpuinfo_arm *cpu_info; | |
144 | struct cpumask *cpumask; | |
145 | unsigned long cpuid; | |
146 | int cpu; | |
147 | ||
148 | cpumask = kzalloc(cpumask_size(), GFP_KERNEL); | |
149 | if (!cpumask) | |
150 | return -ENOMEM; | |
151 | ||
152 | for_each_possible_cpu(cpu) { | |
153 | cpu_info = &per_cpu(cpu_data, cpu); | |
154 | cpuid = is_smp() ? cpu_info->cpuid : read_cpuid_id(); | |
155 | ||
156 | /* read cpu id part number */ | |
157 | if ((cpuid & 0xFFF0) == cpu_id) | |
158 | cpumask_set_cpu(cpu, cpumask); | |
159 | } | |
160 | ||
161 | drv->cpumask = cpumask; | |
162 | ||
163 | return 0; | |
164 | } | |
165 | ||
166 | static int __init bl_idle_init(void) | |
167 | { | |
168 | int ret; | |
169 | ||
170 | /* | |
171 | * Initialize the driver just for a compliant set of machines | |
172 | */ | |
173 | if (!of_machine_is_compatible("arm,vexpress,v2p-ca15_a7")) | |
174 | return -ENODEV; | |
175 | /* | |
176 | * For now the differentiation between little and big cores | |
177 | * is based on the part number. A7 cores are considered little | |
178 | * cores, A15 are considered big cores. This distinction may | |
179 | * evolve in the future with a more generic matching approach. | |
180 | */ | |
181 | ret = bl_idle_driver_init(&bl_idle_little_driver, | |
182 | ARM_CPU_PART_CORTEX_A7); | |
183 | if (ret) | |
184 | return ret; | |
185 | ||
186 | ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15); | |
187 | if (ret) | |
188 | goto out_uninit_little; | |
189 | ||
190 | ret = cpuidle_register(&bl_idle_little_driver, NULL); | |
191 | if (ret) | |
192 | goto out_uninit_big; | |
193 | ||
194 | ret = cpuidle_register(&bl_idle_big_driver, NULL); | |
195 | if (ret) | |
196 | goto out_unregister_little; | |
197 | ||
198 | return 0; | |
199 | ||
200 | out_unregister_little: | |
201 | cpuidle_unregister(&bl_idle_little_driver); | |
202 | out_uninit_big: | |
203 | kfree(bl_idle_big_driver.cpumask); | |
204 | out_uninit_little: | |
205 | kfree(bl_idle_little_driver.cpumask); | |
206 | ||
207 | return ret; | |
208 | } | |
209 | device_initcall(bl_idle_init); |