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803 lines
20 KiB
803 lines
20 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* arch/arm/common/bL_switcher.c -- big.LITTLE cluster switcher core driver |
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* |
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* Created by: Nicolas Pitre, March 2012 |
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* Copyright: (C) 2012-2013 Linaro Limited |
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*/ |
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|
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#include <linux/atomic.h> |
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#include <linux/init.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/sched/signal.h> |
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#include <uapi/linux/sched/types.h> |
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#include <linux/interrupt.h> |
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#include <linux/cpu_pm.h> |
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#include <linux/cpu.h> |
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#include <linux/cpumask.h> |
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#include <linux/kthread.h> |
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#include <linux/wait.h> |
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#include <linux/time.h> |
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#include <linux/clockchips.h> |
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#include <linux/hrtimer.h> |
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#include <linux/tick.h> |
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#include <linux/notifier.h> |
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#include <linux/mm.h> |
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#include <linux/mutex.h> |
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#include <linux/smp.h> |
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#include <linux/spinlock.h> |
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#include <linux/string.h> |
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#include <linux/sysfs.h> |
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#include <linux/irqchip/arm-gic.h> |
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#include <linux/moduleparam.h> |
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#include <asm/smp_plat.h> |
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#include <asm/cputype.h> |
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#include <asm/suspend.h> |
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#include <asm/mcpm.h> |
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#include <asm/bL_switcher.h> |
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#define CREATE_TRACE_POINTS |
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#include <trace/events/power_cpu_migrate.h> |
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/* |
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* Use our own MPIDR accessors as the generic ones in asm/cputype.h have |
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* __attribute_const__ and we don't want the compiler to assume any |
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* constness here as the value _does_ change along some code paths. |
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*/ |
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static int read_mpidr(void) |
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{ |
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unsigned int id; |
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asm volatile ("mrc p15, 0, %0, c0, c0, 5" : "=r" (id)); |
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return id & MPIDR_HWID_BITMASK; |
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} |
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/* |
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* bL switcher core code. |
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*/ |
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static void bL_do_switch(void *_arg) |
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{ |
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unsigned ib_mpidr, ib_cpu, ib_cluster; |
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long volatile handshake, **handshake_ptr = _arg; |
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pr_debug("%s\n", __func__); |
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ib_mpidr = cpu_logical_map(smp_processor_id()); |
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ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0); |
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ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1); |
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/* Advertise our handshake location */ |
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if (handshake_ptr) { |
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handshake = 0; |
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*handshake_ptr = &handshake; |
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} else |
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handshake = -1; |
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/* |
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* Our state has been saved at this point. Let's release our |
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* inbound CPU. |
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*/ |
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mcpm_set_entry_vector(ib_cpu, ib_cluster, cpu_resume); |
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sev(); |
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/* |
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* From this point, we must assume that our counterpart CPU might |
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* have taken over in its parallel world already, as if execution |
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* just returned from cpu_suspend(). It is therefore important to |
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* be very careful not to make any change the other guy is not |
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* expecting. This is why we need stack isolation. |
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* |
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* Fancy under cover tasks could be performed here. For now |
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* we have none. |
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*/ |
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/* |
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* Let's wait until our inbound is alive. |
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*/ |
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while (!handshake) { |
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wfe(); |
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smp_mb(); |
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} |
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/* Let's put ourself down. */ |
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mcpm_cpu_power_down(); |
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/* should never get here */ |
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BUG(); |
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} |
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/* |
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* Stack isolation. To ensure 'current' remains valid, we just use another |
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* piece of our thread's stack space which should be fairly lightly used. |
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* The selected area starts just above the thread_info structure located |
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* at the very bottom of the stack, aligned to a cache line, and indexed |
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* with the cluster number. |
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*/ |
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#define STACK_SIZE 512 |
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extern void call_with_stack(void (*fn)(void *), void *arg, void *sp); |
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static int bL_switchpoint(unsigned long _arg) |
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{ |
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unsigned int mpidr = read_mpidr(); |
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unsigned int clusterid = MPIDR_AFFINITY_LEVEL(mpidr, 1); |
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void *stack = current_thread_info() + 1; |
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stack = PTR_ALIGN(stack, L1_CACHE_BYTES); |
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stack += clusterid * STACK_SIZE + STACK_SIZE; |
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call_with_stack(bL_do_switch, (void *)_arg, stack); |
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BUG(); |
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} |
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/* |
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* Generic switcher interface |
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*/ |
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static unsigned int bL_gic_id[MAX_CPUS_PER_CLUSTER][MAX_NR_CLUSTERS]; |
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static int bL_switcher_cpu_pairing[NR_CPUS]; |
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/* |
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* bL_switch_to - Switch to a specific cluster for the current CPU |
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* @new_cluster_id: the ID of the cluster to switch to. |
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* |
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* This function must be called on the CPU to be switched. |
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* Returns 0 on success, else a negative status code. |
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*/ |
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static int bL_switch_to(unsigned int new_cluster_id) |
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{ |
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unsigned int mpidr, this_cpu, that_cpu; |
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unsigned int ob_mpidr, ob_cpu, ob_cluster, ib_mpidr, ib_cpu, ib_cluster; |
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struct completion inbound_alive; |
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long volatile *handshake_ptr; |
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int ipi_nr, ret; |
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this_cpu = smp_processor_id(); |
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ob_mpidr = read_mpidr(); |
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ob_cpu = MPIDR_AFFINITY_LEVEL(ob_mpidr, 0); |
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ob_cluster = MPIDR_AFFINITY_LEVEL(ob_mpidr, 1); |
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BUG_ON(cpu_logical_map(this_cpu) != ob_mpidr); |
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if (new_cluster_id == ob_cluster) |
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return 0; |
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that_cpu = bL_switcher_cpu_pairing[this_cpu]; |
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ib_mpidr = cpu_logical_map(that_cpu); |
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ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0); |
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ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1); |
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pr_debug("before switch: CPU %d MPIDR %#x -> %#x\n", |
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this_cpu, ob_mpidr, ib_mpidr); |
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this_cpu = smp_processor_id(); |
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/* Close the gate for our entry vectors */ |
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mcpm_set_entry_vector(ob_cpu, ob_cluster, NULL); |
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mcpm_set_entry_vector(ib_cpu, ib_cluster, NULL); |
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/* Install our "inbound alive" notifier. */ |
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init_completion(&inbound_alive); |
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ipi_nr = register_ipi_completion(&inbound_alive, this_cpu); |
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ipi_nr |= ((1 << 16) << bL_gic_id[ob_cpu][ob_cluster]); |
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mcpm_set_early_poke(ib_cpu, ib_cluster, gic_get_sgir_physaddr(), ipi_nr); |
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/* |
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* Let's wake up the inbound CPU now in case it requires some delay |
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* to come online, but leave it gated in our entry vector code. |
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*/ |
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ret = mcpm_cpu_power_up(ib_cpu, ib_cluster); |
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if (ret) { |
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pr_err("%s: mcpm_cpu_power_up() returned %d\n", __func__, ret); |
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return ret; |
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} |
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/* |
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* Raise a SGI on the inbound CPU to make sure it doesn't stall |
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* in a possible WFI, such as in bL_power_down(). |
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*/ |
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gic_send_sgi(bL_gic_id[ib_cpu][ib_cluster], 0); |
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/* |
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* Wait for the inbound to come up. This allows for other |
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* tasks to be scheduled in the mean time. |
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*/ |
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wait_for_completion(&inbound_alive); |
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mcpm_set_early_poke(ib_cpu, ib_cluster, 0, 0); |
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/* |
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* From this point we are entering the switch critical zone |
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* and can't take any interrupts anymore. |
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*/ |
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local_irq_disable(); |
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local_fiq_disable(); |
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trace_cpu_migrate_begin(ktime_get_real_ns(), ob_mpidr); |
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/* redirect GIC's SGIs to our counterpart */ |
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gic_migrate_target(bL_gic_id[ib_cpu][ib_cluster]); |
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tick_suspend_local(); |
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ret = cpu_pm_enter(); |
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/* we can not tolerate errors at this point */ |
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if (ret) |
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panic("%s: cpu_pm_enter() returned %d\n", __func__, ret); |
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/* Swap the physical CPUs in the logical map for this logical CPU. */ |
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cpu_logical_map(this_cpu) = ib_mpidr; |
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cpu_logical_map(that_cpu) = ob_mpidr; |
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/* Let's do the actual CPU switch. */ |
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ret = cpu_suspend((unsigned long)&handshake_ptr, bL_switchpoint); |
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if (ret > 0) |
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panic("%s: cpu_suspend() returned %d\n", __func__, ret); |
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/* We are executing on the inbound CPU at this point */ |
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mpidr = read_mpidr(); |
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pr_debug("after switch: CPU %d MPIDR %#x\n", this_cpu, mpidr); |
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BUG_ON(mpidr != ib_mpidr); |
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mcpm_cpu_powered_up(); |
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ret = cpu_pm_exit(); |
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tick_resume_local(); |
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trace_cpu_migrate_finish(ktime_get_real_ns(), ib_mpidr); |
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local_fiq_enable(); |
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local_irq_enable(); |
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*handshake_ptr = 1; |
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dsb_sev(); |
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if (ret) |
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pr_err("%s exiting with error %d\n", __func__, ret); |
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return ret; |
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} |
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struct bL_thread { |
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spinlock_t lock; |
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struct task_struct *task; |
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wait_queue_head_t wq; |
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int wanted_cluster; |
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struct completion started; |
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bL_switch_completion_handler completer; |
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void *completer_cookie; |
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}; |
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static struct bL_thread bL_threads[NR_CPUS]; |
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static int bL_switcher_thread(void *arg) |
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{ |
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struct bL_thread *t = arg; |
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int cluster; |
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bL_switch_completion_handler completer; |
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void *completer_cookie; |
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sched_set_fifo_low(current); |
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complete(&t->started); |
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do { |
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if (signal_pending(current)) |
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flush_signals(current); |
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wait_event_interruptible(t->wq, |
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t->wanted_cluster != -1 || |
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kthread_should_stop()); |
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spin_lock(&t->lock); |
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cluster = t->wanted_cluster; |
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completer = t->completer; |
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completer_cookie = t->completer_cookie; |
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t->wanted_cluster = -1; |
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t->completer = NULL; |
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spin_unlock(&t->lock); |
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if (cluster != -1) { |
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bL_switch_to(cluster); |
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if (completer) |
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completer(completer_cookie); |
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} |
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} while (!kthread_should_stop()); |
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return 0; |
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} |
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static struct task_struct *bL_switcher_thread_create(int cpu, void *arg) |
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{ |
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struct task_struct *task; |
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task = kthread_create_on_node(bL_switcher_thread, arg, |
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cpu_to_node(cpu), "kswitcher_%d", cpu); |
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if (!IS_ERR(task)) { |
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kthread_bind(task, cpu); |
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wake_up_process(task); |
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} else |
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pr_err("%s failed for CPU %d\n", __func__, cpu); |
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return task; |
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} |
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/* |
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* bL_switch_request_cb - Switch to a specific cluster for the given CPU, |
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* with completion notification via a callback |
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* |
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* @cpu: the CPU to switch |
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* @new_cluster_id: the ID of the cluster to switch to. |
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* @completer: switch completion callback. if non-NULL, |
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* @completer(@completer_cookie) will be called on completion of |
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* the switch, in non-atomic context. |
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* @completer_cookie: opaque context argument for @completer. |
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* |
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* This function causes a cluster switch on the given CPU by waking up |
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* the appropriate switcher thread. This function may or may not return |
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* before the switch has occurred. |
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* |
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* If a @completer callback function is supplied, it will be called when |
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* the switch is complete. This can be used to determine asynchronously |
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* when the switch is complete, regardless of when bL_switch_request() |
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* returns. When @completer is supplied, no new switch request is permitted |
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* for the affected CPU until after the switch is complete, and @completer |
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* has returned. |
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*/ |
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int bL_switch_request_cb(unsigned int cpu, unsigned int new_cluster_id, |
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bL_switch_completion_handler completer, |
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void *completer_cookie) |
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{ |
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struct bL_thread *t; |
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if (cpu >= ARRAY_SIZE(bL_threads)) { |
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pr_err("%s: cpu %d out of bounds\n", __func__, cpu); |
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return -EINVAL; |
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} |
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t = &bL_threads[cpu]; |
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if (IS_ERR(t->task)) |
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return PTR_ERR(t->task); |
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if (!t->task) |
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return -ESRCH; |
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spin_lock(&t->lock); |
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if (t->completer) { |
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spin_unlock(&t->lock); |
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return -EBUSY; |
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} |
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t->completer = completer; |
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t->completer_cookie = completer_cookie; |
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t->wanted_cluster = new_cluster_id; |
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spin_unlock(&t->lock); |
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wake_up(&t->wq); |
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return 0; |
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} |
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EXPORT_SYMBOL_GPL(bL_switch_request_cb); |
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/* |
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* Activation and configuration code. |
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*/ |
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static DEFINE_MUTEX(bL_switcher_activation_lock); |
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static BLOCKING_NOTIFIER_HEAD(bL_activation_notifier); |
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static unsigned int bL_switcher_active; |
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static unsigned int bL_switcher_cpu_original_cluster[NR_CPUS]; |
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static cpumask_t bL_switcher_removed_logical_cpus; |
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int bL_switcher_register_notifier(struct notifier_block *nb) |
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{ |
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return blocking_notifier_chain_register(&bL_activation_notifier, nb); |
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} |
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EXPORT_SYMBOL_GPL(bL_switcher_register_notifier); |
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int bL_switcher_unregister_notifier(struct notifier_block *nb) |
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{ |
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return blocking_notifier_chain_unregister(&bL_activation_notifier, nb); |
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} |
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EXPORT_SYMBOL_GPL(bL_switcher_unregister_notifier); |
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static int bL_activation_notify(unsigned long val) |
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{ |
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int ret; |
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ret = blocking_notifier_call_chain(&bL_activation_notifier, val, NULL); |
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if (ret & NOTIFY_STOP_MASK) |
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pr_err("%s: notifier chain failed with status 0x%x\n", |
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__func__, ret); |
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return notifier_to_errno(ret); |
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} |
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static void bL_switcher_restore_cpus(void) |
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{ |
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int i; |
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for_each_cpu(i, &bL_switcher_removed_logical_cpus) { |
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struct device *cpu_dev = get_cpu_device(i); |
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int ret = device_online(cpu_dev); |
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if (ret) |
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dev_err(cpu_dev, "switcher: unable to restore CPU\n"); |
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} |
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} |
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static int bL_switcher_halve_cpus(void) |
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{ |
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int i, j, cluster_0, gic_id, ret; |
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unsigned int cpu, cluster, mask; |
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cpumask_t available_cpus; |
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/* First pass to validate what we have */ |
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mask = 0; |
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for_each_online_cpu(i) { |
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cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0); |
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cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); |
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if (cluster >= 2) { |
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pr_err("%s: only dual cluster systems are supported\n", __func__); |
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return -EINVAL; |
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} |
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if (WARN_ON(cpu >= MAX_CPUS_PER_CLUSTER)) |
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return -EINVAL; |
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mask |= (1 << cluster); |
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} |
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if (mask != 3) { |
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pr_err("%s: no CPU pairing possible\n", __func__); |
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return -EINVAL; |
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} |
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/* |
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* Now let's do the pairing. We match each CPU with another CPU |
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* from a different cluster. To get a uniform scheduling behavior |
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* without fiddling with CPU topology and compute capacity data, |
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* we'll use logical CPUs initially belonging to the same cluster. |
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*/ |
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memset(bL_switcher_cpu_pairing, -1, sizeof(bL_switcher_cpu_pairing)); |
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cpumask_copy(&available_cpus, cpu_online_mask); |
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cluster_0 = -1; |
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for_each_cpu(i, &available_cpus) { |
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int match = -1; |
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cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); |
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if (cluster_0 == -1) |
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cluster_0 = cluster; |
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if (cluster != cluster_0) |
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continue; |
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cpumask_clear_cpu(i, &available_cpus); |
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for_each_cpu(j, &available_cpus) { |
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cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(j), 1); |
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/* |
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* Let's remember the last match to create "odd" |
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* pairings on purpose in order for other code not |
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* to assume any relation between physical and |
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* logical CPU numbers. |
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*/ |
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if (cluster != cluster_0) |
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match = j; |
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} |
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if (match != -1) { |
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bL_switcher_cpu_pairing[i] = match; |
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cpumask_clear_cpu(match, &available_cpus); |
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pr_info("CPU%d paired with CPU%d\n", i, match); |
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} |
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} |
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/* |
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* Now we disable the unwanted CPUs i.e. everything that has no |
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* pairing information (that includes the pairing counterparts). |
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*/ |
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cpumask_clear(&bL_switcher_removed_logical_cpus); |
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for_each_online_cpu(i) { |
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cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 0); |
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cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(i), 1); |
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/* Let's take note of the GIC ID for this CPU */ |
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gic_id = gic_get_cpu_id(i); |
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if (gic_id < 0) { |
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pr_err("%s: bad GIC ID for CPU %d\n", __func__, i); |
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bL_switcher_restore_cpus(); |
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return -EINVAL; |
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} |
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bL_gic_id[cpu][cluster] = gic_id; |
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pr_info("GIC ID for CPU %u cluster %u is %u\n", |
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cpu, cluster, gic_id); |
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if (bL_switcher_cpu_pairing[i] != -1) { |
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bL_switcher_cpu_original_cluster[i] = cluster; |
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continue; |
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} |
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ret = device_offline(get_cpu_device(i)); |
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if (ret) { |
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bL_switcher_restore_cpus(); |
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return ret; |
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} |
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cpumask_set_cpu(i, &bL_switcher_removed_logical_cpus); |
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} |
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return 0; |
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} |
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/* Determine the logical CPU a given physical CPU is grouped on. */ |
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int bL_switcher_get_logical_index(u32 mpidr) |
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{ |
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int cpu; |
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if (!bL_switcher_active) |
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return -EUNATCH; |
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mpidr &= MPIDR_HWID_BITMASK; |
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for_each_online_cpu(cpu) { |
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int pairing = bL_switcher_cpu_pairing[cpu]; |
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if (pairing == -1) |
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continue; |
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if ((mpidr == cpu_logical_map(cpu)) || |
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(mpidr == cpu_logical_map(pairing))) |
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return cpu; |
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} |
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return -EINVAL; |
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} |
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static void bL_switcher_trace_trigger_cpu(void *__always_unused info) |
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{ |
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trace_cpu_migrate_current(ktime_get_real_ns(), read_mpidr()); |
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} |
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int bL_switcher_trace_trigger(void) |
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{ |
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preempt_disable(); |
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bL_switcher_trace_trigger_cpu(NULL); |
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smp_call_function(bL_switcher_trace_trigger_cpu, NULL, true); |
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preempt_enable(); |
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return 0; |
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} |
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EXPORT_SYMBOL_GPL(bL_switcher_trace_trigger); |
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|
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static int bL_switcher_enable(void) |
|
{ |
|
int cpu, ret; |
|
|
|
mutex_lock(&bL_switcher_activation_lock); |
|
lock_device_hotplug(); |
|
if (bL_switcher_active) { |
|
unlock_device_hotplug(); |
|
mutex_unlock(&bL_switcher_activation_lock); |
|
return 0; |
|
} |
|
|
|
pr_info("big.LITTLE switcher initializing\n"); |
|
|
|
ret = bL_activation_notify(BL_NOTIFY_PRE_ENABLE); |
|
if (ret) |
|
goto error; |
|
|
|
ret = bL_switcher_halve_cpus(); |
|
if (ret) |
|
goto error; |
|
|
|
bL_switcher_trace_trigger(); |
|
|
|
for_each_online_cpu(cpu) { |
|
struct bL_thread *t = &bL_threads[cpu]; |
|
spin_lock_init(&t->lock); |
|
init_waitqueue_head(&t->wq); |
|
init_completion(&t->started); |
|
t->wanted_cluster = -1; |
|
t->task = bL_switcher_thread_create(cpu, t); |
|
} |
|
|
|
bL_switcher_active = 1; |
|
bL_activation_notify(BL_NOTIFY_POST_ENABLE); |
|
pr_info("big.LITTLE switcher initialized\n"); |
|
goto out; |
|
|
|
error: |
|
pr_warn("big.LITTLE switcher initialization failed\n"); |
|
bL_activation_notify(BL_NOTIFY_POST_DISABLE); |
|
|
|
out: |
|
unlock_device_hotplug(); |
|
mutex_unlock(&bL_switcher_activation_lock); |
|
return ret; |
|
} |
|
|
|
#ifdef CONFIG_SYSFS |
|
|
|
static void bL_switcher_disable(void) |
|
{ |
|
unsigned int cpu, cluster; |
|
struct bL_thread *t; |
|
struct task_struct *task; |
|
|
|
mutex_lock(&bL_switcher_activation_lock); |
|
lock_device_hotplug(); |
|
|
|
if (!bL_switcher_active) |
|
goto out; |
|
|
|
if (bL_activation_notify(BL_NOTIFY_PRE_DISABLE) != 0) { |
|
bL_activation_notify(BL_NOTIFY_POST_ENABLE); |
|
goto out; |
|
} |
|
|
|
bL_switcher_active = 0; |
|
|
|
/* |
|
* To deactivate the switcher, we must shut down the switcher |
|
* threads to prevent any other requests from being accepted. |
|
* Then, if the final cluster for given logical CPU is not the |
|
* same as the original one, we'll recreate a switcher thread |
|
* just for the purpose of switching the CPU back without any |
|
* possibility for interference from external requests. |
|
*/ |
|
for_each_online_cpu(cpu) { |
|
t = &bL_threads[cpu]; |
|
task = t->task; |
|
t->task = NULL; |
|
if (!task || IS_ERR(task)) |
|
continue; |
|
kthread_stop(task); |
|
/* no more switch may happen on this CPU at this point */ |
|
cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1); |
|
if (cluster == bL_switcher_cpu_original_cluster[cpu]) |
|
continue; |
|
init_completion(&t->started); |
|
t->wanted_cluster = bL_switcher_cpu_original_cluster[cpu]; |
|
task = bL_switcher_thread_create(cpu, t); |
|
if (!IS_ERR(task)) { |
|
wait_for_completion(&t->started); |
|
kthread_stop(task); |
|
cluster = MPIDR_AFFINITY_LEVEL(cpu_logical_map(cpu), 1); |
|
if (cluster == bL_switcher_cpu_original_cluster[cpu]) |
|
continue; |
|
} |
|
/* If execution gets here, we're in trouble. */ |
|
pr_crit("%s: unable to restore original cluster for CPU %d\n", |
|
__func__, cpu); |
|
pr_crit("%s: CPU %d can't be restored\n", |
|
__func__, bL_switcher_cpu_pairing[cpu]); |
|
cpumask_clear_cpu(bL_switcher_cpu_pairing[cpu], |
|
&bL_switcher_removed_logical_cpus); |
|
} |
|
|
|
bL_switcher_restore_cpus(); |
|
bL_switcher_trace_trigger(); |
|
|
|
bL_activation_notify(BL_NOTIFY_POST_DISABLE); |
|
|
|
out: |
|
unlock_device_hotplug(); |
|
mutex_unlock(&bL_switcher_activation_lock); |
|
} |
|
|
|
static ssize_t bL_switcher_active_show(struct kobject *kobj, |
|
struct kobj_attribute *attr, char *buf) |
|
{ |
|
return sprintf(buf, "%u\n", bL_switcher_active); |
|
} |
|
|
|
static ssize_t bL_switcher_active_store(struct kobject *kobj, |
|
struct kobj_attribute *attr, const char *buf, size_t count) |
|
{ |
|
int ret; |
|
|
|
switch (buf[0]) { |
|
case '0': |
|
bL_switcher_disable(); |
|
ret = 0; |
|
break; |
|
case '1': |
|
ret = bL_switcher_enable(); |
|
break; |
|
default: |
|
ret = -EINVAL; |
|
} |
|
|
|
return (ret >= 0) ? count : ret; |
|
} |
|
|
|
static ssize_t bL_switcher_trace_trigger_store(struct kobject *kobj, |
|
struct kobj_attribute *attr, const char *buf, size_t count) |
|
{ |
|
int ret = bL_switcher_trace_trigger(); |
|
|
|
return ret ? ret : count; |
|
} |
|
|
|
static struct kobj_attribute bL_switcher_active_attr = |
|
__ATTR(active, 0644, bL_switcher_active_show, bL_switcher_active_store); |
|
|
|
static struct kobj_attribute bL_switcher_trace_trigger_attr = |
|
__ATTR(trace_trigger, 0200, NULL, bL_switcher_trace_trigger_store); |
|
|
|
static struct attribute *bL_switcher_attrs[] = { |
|
&bL_switcher_active_attr.attr, |
|
&bL_switcher_trace_trigger_attr.attr, |
|
NULL, |
|
}; |
|
|
|
static struct attribute_group bL_switcher_attr_group = { |
|
.attrs = bL_switcher_attrs, |
|
}; |
|
|
|
static struct kobject *bL_switcher_kobj; |
|
|
|
static int __init bL_switcher_sysfs_init(void) |
|
{ |
|
int ret; |
|
|
|
bL_switcher_kobj = kobject_create_and_add("bL_switcher", kernel_kobj); |
|
if (!bL_switcher_kobj) |
|
return -ENOMEM; |
|
ret = sysfs_create_group(bL_switcher_kobj, &bL_switcher_attr_group); |
|
if (ret) |
|
kobject_put(bL_switcher_kobj); |
|
return ret; |
|
} |
|
|
|
#endif /* CONFIG_SYSFS */ |
|
|
|
bool bL_switcher_get_enabled(void) |
|
{ |
|
mutex_lock(&bL_switcher_activation_lock); |
|
|
|
return bL_switcher_active; |
|
} |
|
EXPORT_SYMBOL_GPL(bL_switcher_get_enabled); |
|
|
|
void bL_switcher_put_enabled(void) |
|
{ |
|
mutex_unlock(&bL_switcher_activation_lock); |
|
} |
|
EXPORT_SYMBOL_GPL(bL_switcher_put_enabled); |
|
|
|
/* |
|
* Veto any CPU hotplug operation on those CPUs we've removed |
|
* while the switcher is active. |
|
* We're just not ready to deal with that given the trickery involved. |
|
*/ |
|
static int bL_switcher_cpu_pre(unsigned int cpu) |
|
{ |
|
int pairing; |
|
|
|
if (!bL_switcher_active) |
|
return 0; |
|
|
|
pairing = bL_switcher_cpu_pairing[cpu]; |
|
|
|
if (pairing == -1) |
|
return -EINVAL; |
|
return 0; |
|
} |
|
|
|
static bool no_bL_switcher; |
|
core_param(no_bL_switcher, no_bL_switcher, bool, 0644); |
|
|
|
static int __init bL_switcher_init(void) |
|
{ |
|
int ret; |
|
|
|
if (!mcpm_is_available()) |
|
return -ENODEV; |
|
|
|
cpuhp_setup_state_nocalls(CPUHP_ARM_BL_PREPARE, "arm/bl:prepare", |
|
bL_switcher_cpu_pre, NULL); |
|
ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "arm/bl:predown", |
|
NULL, bL_switcher_cpu_pre); |
|
if (ret < 0) { |
|
cpuhp_remove_state_nocalls(CPUHP_ARM_BL_PREPARE); |
|
pr_err("bL_switcher: Failed to allocate a hotplug state\n"); |
|
return ret; |
|
} |
|
if (!no_bL_switcher) { |
|
ret = bL_switcher_enable(); |
|
if (ret) |
|
return ret; |
|
} |
|
|
|
#ifdef CONFIG_SYSFS |
|
ret = bL_switcher_sysfs_init(); |
|
if (ret) |
|
pr_err("%s: unable to create sysfs entry\n", __func__); |
|
#endif |
|
|
|
return 0; |
|
} |
|
|
|
late_initcall(bL_switcher_init);
|
|
|