2 * arch/arm/common/mcpm_entry.c -- entry point for multi-cluster PM
4 * Created by: Nicolas Pitre, March 2012
5 * Copyright: (C) 2012-2013 Linaro Limited
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.
12 #include <linux/kernel.h>
13 #include <linux/init.h>
14 #include <linux/irqflags.h>
15 #include <linux/cpu_pm.h>
18 #include <asm/cacheflush.h>
19 #include <asm/idmap.h>
20 #include <asm/cputype.h>
21 #include <asm/suspend.h>
23 extern unsigned long mcpm_entry_vectors[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER];
25 void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr)
27 unsigned long val = ptr ? virt_to_phys(ptr) : 0;
28 mcpm_entry_vectors[cluster][cpu] = val;
29 sync_cache_w(&mcpm_entry_vectors[cluster][cpu]);
32 extern unsigned long mcpm_entry_early_pokes[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER][2];
34 void mcpm_set_early_poke(unsigned cpu, unsigned cluster,
35 unsigned long poke_phys_addr, unsigned long poke_val)
37 unsigned long *poke = &mcpm_entry_early_pokes[cluster][cpu][0];
38 poke[0] = poke_phys_addr;
40 __sync_cache_range_w(poke, 2 * sizeof(*poke));
43 static const struct mcpm_platform_ops *platform_ops;
45 int __init mcpm_platform_register(const struct mcpm_platform_ops *ops)
53 bool mcpm_is_available(void)
55 return (platform_ops) ? true : false;
58 int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster)
61 return -EUNATCH; /* try not to shadow power_up errors */
63 return platform_ops->power_up(cpu, cluster);
66 typedef void (*phys_reset_t)(unsigned long);
68 void mcpm_cpu_power_down(void)
70 phys_reset_t phys_reset;
72 if (WARN_ON_ONCE(!platform_ops || !platform_ops->power_down))
74 BUG_ON(!irqs_disabled());
77 * Do this before calling into the power_down method,
78 * as it might not always be safe to do afterwards.
80 setup_mm_for_reboot();
82 platform_ops->power_down();
85 * It is possible for a power_up request to happen concurrently
86 * with a power_down request for the same CPU. In this case the
87 * power_down method might not be able to actually enter a
88 * powered down state with the WFI instruction if the power_up
89 * method has removed the required reset condition. The
90 * power_down method is then allowed to return. We must perform
91 * a re-entry in the kernel as if the power_up method just had
92 * deasserted reset on the CPU.
94 * To simplify race issues, the platform specific implementation
95 * must accommodate for the possibility of unordered calls to
96 * power_down and power_up with a usage count. Therefore, if a
97 * call to power_up is issued for a CPU that is not down, then
98 * the next call to power_down must not attempt a full shutdown
99 * but only do the minimum (normally disabling L1 cache and CPU
100 * coherency) and return just as if a concurrent power_up request
101 * had happened as described above.
104 phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
105 phys_reset(virt_to_phys(mcpm_entry_point));
107 /* should never get here */
111 int mcpm_wait_for_cpu_powerdown(unsigned int cpu, unsigned int cluster)
115 if (WARN_ON_ONCE(!platform_ops || !platform_ops->wait_for_powerdown))
118 ret = platform_ops->wait_for_powerdown(cpu, cluster);
120 pr_warn("%s: cpu %u, cluster %u failed to power down (%d)\n",
121 __func__, cpu, cluster, ret);
126 void mcpm_cpu_suspend(u64 expected_residency)
128 phys_reset_t phys_reset;
130 if (WARN_ON_ONCE(!platform_ops || !platform_ops->suspend))
132 BUG_ON(!irqs_disabled());
134 /* Very similar to mcpm_cpu_power_down() */
135 setup_mm_for_reboot();
136 platform_ops->suspend(expected_residency);
137 phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
138 phys_reset(virt_to_phys(mcpm_entry_point));
142 int mcpm_cpu_powered_up(void)
146 if (platform_ops->powered_up)
147 platform_ops->powered_up();
151 #ifdef CONFIG_ARM_CPU_SUSPEND
153 static int __init nocache_trampoline(unsigned long _arg)
155 void (*cache_disable)(void) = (void *)_arg;
156 unsigned int mpidr = read_cpuid_mpidr();
157 unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
158 unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
159 phys_reset_t phys_reset;
161 mcpm_set_entry_vector(cpu, cluster, cpu_resume);
162 setup_mm_for_reboot();
164 __mcpm_cpu_going_down(cpu, cluster);
165 BUG_ON(!__mcpm_outbound_enter_critical(cpu, cluster));
167 __mcpm_outbound_leave_critical(cluster, CLUSTER_DOWN);
168 __mcpm_cpu_down(cpu, cluster);
170 phys_reset = (phys_reset_t)(unsigned long)virt_to_phys(cpu_reset);
171 phys_reset(virt_to_phys(mcpm_entry_point));
175 int __init mcpm_loopback(void (*cache_disable)(void))
180 * We're going to soft-restart the current CPU through the
181 * low-level MCPM code by leveraging the suspend/resume
182 * infrastructure. Let's play it safe by using cpu_pm_enter()
183 * in case the CPU init code path resets the VFP or similar.
187 ret = cpu_pm_enter();
189 ret = cpu_suspend((unsigned long)cache_disable, nocache_trampoline);
195 pr_err("%s returned %d\n", __func__, ret);
201 struct sync_struct mcpm_sync;
204 * __mcpm_cpu_going_down: Indicates that the cpu is being torn down.
205 * This must be called at the point of committing to teardown of a CPU.
206 * The CPU cache (SCTRL.C bit) is expected to still be active.
208 void __mcpm_cpu_going_down(unsigned int cpu, unsigned int cluster)
210 mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_GOING_DOWN;
211 sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu);
215 * __mcpm_cpu_down: Indicates that cpu teardown is complete and that the
216 * cluster can be torn down without disrupting this CPU.
217 * To avoid deadlocks, this must be called before a CPU is powered down.
218 * The CPU cache (SCTRL.C bit) is expected to be off.
219 * However L2 cache might or might not be active.
221 void __mcpm_cpu_down(unsigned int cpu, unsigned int cluster)
224 mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_DOWN;
225 sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu);
230 * __mcpm_outbound_leave_critical: Leave the cluster teardown critical section.
231 * @state: the final state of the cluster:
232 * CLUSTER_UP: no destructive teardown was done and the cluster has been
233 * restored to the previous state (CPU cache still active); or
234 * CLUSTER_DOWN: the cluster has been torn-down, ready for power-off
235 * (CPU cache disabled, L2 cache either enabled or disabled).
237 void __mcpm_outbound_leave_critical(unsigned int cluster, int state)
240 mcpm_sync.clusters[cluster].cluster = state;
241 sync_cache_w(&mcpm_sync.clusters[cluster].cluster);
246 * __mcpm_outbound_enter_critical: Enter the cluster teardown critical section.
247 * This function should be called by the last man, after local CPU teardown
248 * is complete. CPU cache expected to be active.
251 * false: the critical section was not entered because an inbound CPU was
252 * observed, or the cluster is already being set up;
253 * true: the critical section was entered: it is now safe to tear down the
256 bool __mcpm_outbound_enter_critical(unsigned int cpu, unsigned int cluster)
259 struct mcpm_sync_struct *c = &mcpm_sync.clusters[cluster];
261 /* Warn inbound CPUs that the cluster is being torn down: */
262 c->cluster = CLUSTER_GOING_DOWN;
263 sync_cache_w(&c->cluster);
265 /* Back out if the inbound cluster is already in the critical region: */
266 sync_cache_r(&c->inbound);
267 if (c->inbound == INBOUND_COMING_UP)
271 * Wait for all CPUs to get out of the GOING_DOWN state, so that local
272 * teardown is complete on each CPU before tearing down the cluster.
274 * If any CPU has been woken up again from the DOWN state, then we
275 * shouldn't be taking the cluster down at all: abort in that case.
277 sync_cache_r(&c->cpus);
278 for (i = 0; i < MAX_CPUS_PER_CLUSTER; i++) {
285 cpustate = c->cpus[i].cpu;
286 if (cpustate != CPU_GOING_DOWN)
290 sync_cache_r(&c->cpus[i].cpu);
305 __mcpm_outbound_leave_critical(cluster, CLUSTER_UP);
309 int __mcpm_cluster_state(unsigned int cluster)
311 sync_cache_r(&mcpm_sync.clusters[cluster].cluster);
312 return mcpm_sync.clusters[cluster].cluster;
315 extern unsigned long mcpm_power_up_setup_phys;
317 int __init mcpm_sync_init(
318 void (*power_up_setup)(unsigned int affinity_level))
320 unsigned int i, j, mpidr, this_cluster;
322 BUILD_BUG_ON(MCPM_SYNC_CLUSTER_SIZE * MAX_NR_CLUSTERS != sizeof mcpm_sync);
323 BUG_ON((unsigned long)&mcpm_sync & (__CACHE_WRITEBACK_GRANULE - 1));
326 * Set initial CPU and cluster states.
327 * Only one cluster is assumed to be active at this point.
329 for (i = 0; i < MAX_NR_CLUSTERS; i++) {
330 mcpm_sync.clusters[i].cluster = CLUSTER_DOWN;
331 mcpm_sync.clusters[i].inbound = INBOUND_NOT_COMING_UP;
332 for (j = 0; j < MAX_CPUS_PER_CLUSTER; j++)
333 mcpm_sync.clusters[i].cpus[j].cpu = CPU_DOWN;
335 mpidr = read_cpuid_mpidr();
336 this_cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
337 for_each_online_cpu(i)
338 mcpm_sync.clusters[this_cluster].cpus[i].cpu = CPU_UP;
339 mcpm_sync.clusters[this_cluster].cluster = CLUSTER_UP;
340 sync_cache_w(&mcpm_sync);
342 if (power_up_setup) {
343 mcpm_power_up_setup_phys = virt_to_phys(power_up_setup);
344 sync_cache_w(&mcpm_power_up_setup_phys);