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e8db288e NP |
1 | /* |
2 | * arch/arm/common/mcpm_entry.c -- entry point for multi-cluster PM | |
3 | * | |
4 | * Created by: Nicolas Pitre, March 2012 | |
5 | * Copyright: (C) 2012-2013 Linaro Limited | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | */ | |
11 | ||
7c2b8605 NP |
12 | #include <linux/kernel.h> |
13 | #include <linux/init.h> | |
14 | #include <linux/irqflags.h> | |
15 | ||
e8db288e NP |
16 | #include <asm/mcpm.h> |
17 | #include <asm/cacheflush.h> | |
7c2b8605 | 18 | #include <asm/idmap.h> |
7fe31d28 | 19 | #include <asm/cputype.h> |
e8db288e NP |
20 | |
21 | extern unsigned long mcpm_entry_vectors[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER]; | |
22 | ||
23 | void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr) | |
24 | { | |
25 | unsigned long val = ptr ? virt_to_phys(ptr) : 0; | |
26 | mcpm_entry_vectors[cluster][cpu] = val; | |
27 | sync_cache_w(&mcpm_entry_vectors[cluster][cpu]); | |
28 | } | |
7c2b8605 NP |
29 | |
30 | static const struct mcpm_platform_ops *platform_ops; | |
31 | ||
32 | int __init mcpm_platform_register(const struct mcpm_platform_ops *ops) | |
33 | { | |
34 | if (platform_ops) | |
35 | return -EBUSY; | |
36 | platform_ops = ops; | |
37 | return 0; | |
38 | } | |
39 | ||
40 | int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster) | |
41 | { | |
42 | if (!platform_ops) | |
43 | return -EUNATCH; /* try not to shadow power_up errors */ | |
44 | might_sleep(); | |
45 | return platform_ops->power_up(cpu, cluster); | |
46 | } | |
47 | ||
48 | typedef void (*phys_reset_t)(unsigned long); | |
49 | ||
50 | void mcpm_cpu_power_down(void) | |
51 | { | |
52 | phys_reset_t phys_reset; | |
53 | ||
54 | BUG_ON(!platform_ops); | |
55 | BUG_ON(!irqs_disabled()); | |
56 | ||
57 | /* | |
58 | * Do this before calling into the power_down method, | |
59 | * as it might not always be safe to do afterwards. | |
60 | */ | |
61 | setup_mm_for_reboot(); | |
62 | ||
63 | platform_ops->power_down(); | |
64 | ||
65 | /* | |
66 | * It is possible for a power_up request to happen concurrently | |
67 | * with a power_down request for the same CPU. In this case the | |
68 | * power_down method might not be able to actually enter a | |
69 | * powered down state with the WFI instruction if the power_up | |
70 | * method has removed the required reset condition. The | |
71 | * power_down method is then allowed to return. We must perform | |
72 | * a re-entry in the kernel as if the power_up method just had | |
73 | * deasserted reset on the CPU. | |
74 | * | |
75 | * To simplify race issues, the platform specific implementation | |
76 | * must accommodate for the possibility of unordered calls to | |
77 | * power_down and power_up with a usage count. Therefore, if a | |
78 | * call to power_up is issued for a CPU that is not down, then | |
79 | * the next call to power_down must not attempt a full shutdown | |
80 | * but only do the minimum (normally disabling L1 cache and CPU | |
81 | * coherency) and return just as if a concurrent power_up request | |
82 | * had happened as described above. | |
83 | */ | |
84 | ||
85 | phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset); | |
86 | phys_reset(virt_to_phys(mcpm_entry_point)); | |
87 | ||
88 | /* should never get here */ | |
89 | BUG(); | |
90 | } | |
91 | ||
92 | void mcpm_cpu_suspend(u64 expected_residency) | |
93 | { | |
94 | phys_reset_t phys_reset; | |
95 | ||
96 | BUG_ON(!platform_ops); | |
97 | BUG_ON(!irqs_disabled()); | |
98 | ||
99 | /* Very similar to mcpm_cpu_power_down() */ | |
100 | setup_mm_for_reboot(); | |
101 | platform_ops->suspend(expected_residency); | |
102 | phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset); | |
103 | phys_reset(virt_to_phys(mcpm_entry_point)); | |
104 | BUG(); | |
105 | } | |
106 | ||
107 | int mcpm_cpu_powered_up(void) | |
108 | { | |
109 | if (!platform_ops) | |
110 | return -EUNATCH; | |
111 | if (platform_ops->powered_up) | |
112 | platform_ops->powered_up(); | |
113 | return 0; | |
114 | } | |
7fe31d28 DM |
115 | |
116 | struct sync_struct mcpm_sync; | |
117 | ||
118 | /* | |
119 | * __mcpm_cpu_going_down: Indicates that the cpu is being torn down. | |
120 | * This must be called at the point of committing to teardown of a CPU. | |
121 | * The CPU cache (SCTRL.C bit) is expected to still be active. | |
122 | */ | |
123 | void __mcpm_cpu_going_down(unsigned int cpu, unsigned int cluster) | |
124 | { | |
125 | mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_GOING_DOWN; | |
126 | sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu); | |
127 | } | |
128 | ||
129 | /* | |
130 | * __mcpm_cpu_down: Indicates that cpu teardown is complete and that the | |
131 | * cluster can be torn down without disrupting this CPU. | |
132 | * To avoid deadlocks, this must be called before a CPU is powered down. | |
133 | * The CPU cache (SCTRL.C bit) is expected to be off. | |
134 | * However L2 cache might or might not be active. | |
135 | */ | |
136 | void __mcpm_cpu_down(unsigned int cpu, unsigned int cluster) | |
137 | { | |
138 | dmb(); | |
139 | mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_DOWN; | |
140 | sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu); | |
141 | dsb_sev(); | |
142 | } | |
143 | ||
144 | /* | |
145 | * __mcpm_outbound_leave_critical: Leave the cluster teardown critical section. | |
146 | * @state: the final state of the cluster: | |
147 | * CLUSTER_UP: no destructive teardown was done and the cluster has been | |
148 | * restored to the previous state (CPU cache still active); or | |
149 | * CLUSTER_DOWN: the cluster has been torn-down, ready for power-off | |
150 | * (CPU cache disabled, L2 cache either enabled or disabled). | |
151 | */ | |
152 | void __mcpm_outbound_leave_critical(unsigned int cluster, int state) | |
153 | { | |
154 | dmb(); | |
155 | mcpm_sync.clusters[cluster].cluster = state; | |
156 | sync_cache_w(&mcpm_sync.clusters[cluster].cluster); | |
157 | dsb_sev(); | |
158 | } | |
159 | ||
160 | /* | |
161 | * __mcpm_outbound_enter_critical: Enter the cluster teardown critical section. | |
162 | * This function should be called by the last man, after local CPU teardown | |
163 | * is complete. CPU cache expected to be active. | |
164 | * | |
165 | * Returns: | |
166 | * false: the critical section was not entered because an inbound CPU was | |
167 | * observed, or the cluster is already being set up; | |
168 | * true: the critical section was entered: it is now safe to tear down the | |
169 | * cluster. | |
170 | */ | |
171 | bool __mcpm_outbound_enter_critical(unsigned int cpu, unsigned int cluster) | |
172 | { | |
173 | unsigned int i; | |
174 | struct mcpm_sync_struct *c = &mcpm_sync.clusters[cluster]; | |
175 | ||
176 | /* Warn inbound CPUs that the cluster is being torn down: */ | |
177 | c->cluster = CLUSTER_GOING_DOWN; | |
178 | sync_cache_w(&c->cluster); | |
179 | ||
180 | /* Back out if the inbound cluster is already in the critical region: */ | |
181 | sync_cache_r(&c->inbound); | |
182 | if (c->inbound == INBOUND_COMING_UP) | |
183 | goto abort; | |
184 | ||
185 | /* | |
186 | * Wait for all CPUs to get out of the GOING_DOWN state, so that local | |
187 | * teardown is complete on each CPU before tearing down the cluster. | |
188 | * | |
189 | * If any CPU has been woken up again from the DOWN state, then we | |
190 | * shouldn't be taking the cluster down at all: abort in that case. | |
191 | */ | |
192 | sync_cache_r(&c->cpus); | |
193 | for (i = 0; i < MAX_CPUS_PER_CLUSTER; i++) { | |
194 | int cpustate; | |
195 | ||
196 | if (i == cpu) | |
197 | continue; | |
198 | ||
199 | while (1) { | |
200 | cpustate = c->cpus[i].cpu; | |
201 | if (cpustate != CPU_GOING_DOWN) | |
202 | break; | |
203 | ||
204 | wfe(); | |
205 | sync_cache_r(&c->cpus[i].cpu); | |
206 | } | |
207 | ||
208 | switch (cpustate) { | |
209 | case CPU_DOWN: | |
210 | continue; | |
211 | ||
212 | default: | |
213 | goto abort; | |
214 | } | |
215 | } | |
216 | ||
217 | return true; | |
218 | ||
219 | abort: | |
220 | __mcpm_outbound_leave_critical(cluster, CLUSTER_UP); | |
221 | return false; | |
222 | } | |
223 | ||
224 | int __mcpm_cluster_state(unsigned int cluster) | |
225 | { | |
226 | sync_cache_r(&mcpm_sync.clusters[cluster].cluster); | |
227 | return mcpm_sync.clusters[cluster].cluster; | |
228 | } | |
229 | ||
230 | extern unsigned long mcpm_power_up_setup_phys; | |
231 | ||
232 | int __init mcpm_sync_init( | |
233 | void (*power_up_setup)(unsigned int affinity_level)) | |
234 | { | |
235 | unsigned int i, j, mpidr, this_cluster; | |
236 | ||
237 | BUILD_BUG_ON(MCPM_SYNC_CLUSTER_SIZE * MAX_NR_CLUSTERS != sizeof mcpm_sync); | |
238 | BUG_ON((unsigned long)&mcpm_sync & (__CACHE_WRITEBACK_GRANULE - 1)); | |
239 | ||
240 | /* | |
241 | * Set initial CPU and cluster states. | |
242 | * Only one cluster is assumed to be active at this point. | |
243 | */ | |
244 | for (i = 0; i < MAX_NR_CLUSTERS; i++) { | |
245 | mcpm_sync.clusters[i].cluster = CLUSTER_DOWN; | |
246 | mcpm_sync.clusters[i].inbound = INBOUND_NOT_COMING_UP; | |
247 | for (j = 0; j < MAX_CPUS_PER_CLUSTER; j++) | |
248 | mcpm_sync.clusters[i].cpus[j].cpu = CPU_DOWN; | |
249 | } | |
250 | mpidr = read_cpuid_mpidr(); | |
251 | this_cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); | |
252 | for_each_online_cpu(i) | |
253 | mcpm_sync.clusters[this_cluster].cpus[i].cpu = CPU_UP; | |
254 | mcpm_sync.clusters[this_cluster].cluster = CLUSTER_UP; | |
255 | sync_cache_w(&mcpm_sync); | |
256 | ||
257 | if (power_up_setup) { | |
258 | mcpm_power_up_setup_phys = virt_to_phys(power_up_setup); | |
259 | sync_cache_w(&mcpm_power_up_setup_phys); | |
260 | } | |
261 | ||
262 | return 0; | |
263 | } |