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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 : 0 : 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 : 4948746 : unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
102 : 4948746 : unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
103 : :
104 : 4948746 : 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 : 4613803 : mcpm_cpu_suspend(0);
112 : :
113 : : /* return value != 0 means failure */
114 : 0 : 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 : 0 : static int bl_enter_powerdown(struct cpuidle_device *dev,
127 : : struct cpuidle_driver *drv, int idx)
128 : : {
129 : 4968238 : cpu_pm_enter();
130 : :
131 : 4968176 : cpu_suspend(0, bl_powerdown_finisher);
132 : :
133 : : /* signals the MCPM core that CPU is out of low power state */
134 : 4899384 : mcpm_cpu_powered_up();
135 : :
136 : 4968237 : cpu_pm_exit();
137 : :
138 : 4956431 : return idx;
139 : : }
140 : :
141 : 0 : 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 [ # # ]: 0 : if (!cpumask)
150 : : return -ENOMEM;
151 : :
152 [ # # ]: 0 : for_each_possible_cpu(cpu) {
153 : 0 : cpu_info = &per_cpu(cpu_data, cpu);
154 [ # # ]: 0 : cpuid = is_smp() ? cpu_info->cpuid : read_cpuid_id();
155 : :
156 : : /* read cpu id part number */
157 [ # # ]: 0 : if ((cpuid & 0xFFF0) == cpu_id)
158 : : cpumask_set_cpu(cpu, cpumask);
159 : : }
160 : :
161 : 0 : drv->cpumask = cpumask;
162 : :
163 : : return 0;
164 : : }
165 : :
166 : 0 : 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 [ # # ]: 0 : 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 : 0 : ret = bl_idle_driver_init(&bl_idle_little_driver,
182 : : ARM_CPU_PART_CORTEX_A7);
183 [ # # ]: 0 : if (ret)
184 : : return ret;
185 : :
186 : 0 : ret = bl_idle_driver_init(&bl_idle_big_driver, ARM_CPU_PART_CORTEX_A15);
187 [ # # ]: 0 : if (ret)
188 : : goto out_uninit_little;
189 : :
190 : 0 : ret = cpuidle_register(&bl_idle_little_driver, NULL);
191 [ # # ]: 0 : if (ret)
192 : : goto out_uninit_big;
193 : :
194 : 0 : ret = cpuidle_register(&bl_idle_big_driver, NULL);
195 [ # # ]: 0 : if (ret)
196 : : goto out_unregister_little;
197 : :
198 : : return 0;
199 : :
200 : : out_unregister_little:
201 : 0 : cpuidle_unregister(&bl_idle_little_driver);
202 : : out_uninit_big:
203 : 0 : kfree(bl_idle_big_driver.cpumask);
204 : : out_uninit_little:
205 : 0 : kfree(bl_idle_little_driver.cpumask);
206 : :
207 : 0 : return ret;
208 : : }
209 : : device_initcall(bl_idle_init);
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