1 files changed, 456 insertions, 0 deletions
diff --git a/arch/arm/common/mcpm_entry.c b/arch/arm/common/mcpm_entry.c
new file mode 100644
index 000000000..8a9aeeb50
--- /dev/null
+++ b/arch/arm/common/mcpm_entry.c
@@ -0,0 +1,456 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * arch/arm/common/mcpm_entry.c -- entry point for multi-cluster PM
+ *
+ * Created by:  Nicolas Pitre, March 2012
+ * Copyright:   (C) 2012-2013  Linaro Limited
+ */
+
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/irqflags.h>
+#include <linux/cpu_pm.h>
+
+#include <asm/mcpm.h>
+#include <asm/cacheflush.h>
+#include <asm/idmap.h>
+#include <asm/cputype.h>
+#include <asm/suspend.h>
+
+/*
+ * The public API for this code is documented in arch/arm/include/asm/mcpm.h.
+ * For a comprehensive description of the main algorithm used here, please
+ * see Documentation/arm/cluster-pm-race-avoidance.rst.
+ */
+
+struct sync_struct mcpm_sync;
+
+/*
+ * __mcpm_cpu_going_down: Indicates that the cpu is being torn down.
+ *    This must be called at the point of committing to teardown of a CPU.
+ *    The CPU cache (SCTRL.C bit) is expected to still be active.
+ */
+static void __mcpm_cpu_going_down(unsigned int cpu, unsigned int cluster)
+{
+	mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_GOING_DOWN;
+	sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu);
+}
+
+/*
+ * __mcpm_cpu_down: Indicates that cpu teardown is complete and that the
+ *    cluster can be torn down without disrupting this CPU.
+ *    To avoid deadlocks, this must be called before a CPU is powered down.
+ *    The CPU cache (SCTRL.C bit) is expected to be off.
+ *    However L2 cache might or might not be active.
+ */
+static void __mcpm_cpu_down(unsigned int cpu, unsigned int cluster)
+{
+	dmb();
+	mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_DOWN;
+	sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu);
+	sev();
+}
+
+/*
+ * __mcpm_outbound_leave_critical: Leave the cluster teardown critical section.
+ * @state: the final state of the cluster:
+ *     CLUSTER_UP: no destructive teardown was done and the cluster has been
+ *         restored to the previous state (CPU cache still active); or
+ *     CLUSTER_DOWN: the cluster has been torn-down, ready for power-off
+ *         (CPU cache disabled, L2 cache either enabled or disabled).
+ */
+static void __mcpm_outbound_leave_critical(unsigned int cluster, int state)
+{
+	dmb();
+	mcpm_sync.clusters[cluster].cluster = state;
+	sync_cache_w(&mcpm_sync.clusters[cluster].cluster);
+	sev();
+}
+
+/*
+ * __mcpm_outbound_enter_critical: Enter the cluster teardown critical section.
+ * This function should be called by the last man, after local CPU teardown
+ * is complete.  CPU cache expected to be active.
+ *
+ * Returns:
+ *     false: the critical section was not entered because an inbound CPU was
+ *         observed, or the cluster is already being set up;
+ *     true: the critical section was entered: it is now safe to tear down the
+ *         cluster.
+ */
+static bool __mcpm_outbound_enter_critical(unsigned int cpu, unsigned int cluster)
+{
+	unsigned int i;
+	struct mcpm_sync_struct *c = &mcpm_sync.clusters[cluster];
+
+	/* Warn inbound CPUs that the cluster is being torn down: */
+	c->cluster = CLUSTER_GOING_DOWN;
+	sync_cache_w(&c->cluster);
+
+	/* Back out if the inbound cluster is already in the critical region: */
+	sync_cache_r(&c->inbound);
+	if (c->inbound == INBOUND_COMING_UP)
+		goto abort;
+
+	/*
+	 * Wait for all CPUs to get out of the GOING_DOWN state, so that local
+	 * teardown is complete on each CPU before tearing down the cluster.
+	 *
+	 * If any CPU has been woken up again from the DOWN state, then we
+	 * shouldn't be taking the cluster down at all: abort in that case.
+	 */
+	sync_cache_r(&c->cpus);
+	for (i = 0; i < MAX_CPUS_PER_CLUSTER; i++) {
+		int cpustate;
+
+		if (i == cpu)
+			continue;
+
+		while (1) {
+			cpustate = c->cpus[i].cpu;
+			if (cpustate != CPU_GOING_DOWN)
+				break;
+
+			wfe();
+			sync_cache_r(&c->cpus[i].cpu);
+		}
+
+		switch (cpustate) {
+		case CPU_DOWN:
+			continue;
+
+		default:
+			goto abort;
+		}
+	}
+
+	return true;
+
+abort:
+	__mcpm_outbound_leave_critical(cluster, CLUSTER_UP);
+	return false;
+}
+
+static int __mcpm_cluster_state(unsigned int cluster)
+{
+	sync_cache_r(&mcpm_sync.clusters[cluster].cluster);
+	return mcpm_sync.clusters[cluster].cluster;
+}
+
+extern unsigned long mcpm_entry_vectors[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER];
+
+void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr)
+{
+	unsigned long val = ptr ? __pa_symbol(ptr) : 0;
+	mcpm_entry_vectors[cluster][cpu] = val;
+	sync_cache_w(&mcpm_entry_vectors[cluster][cpu]);
+}
+
+extern unsigned long mcpm_entry_early_pokes[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER][2];
+
+void mcpm_set_early_poke(unsigned cpu, unsigned cluster,
+			 unsigned long poke_phys_addr, unsigned long poke_val)
+{
+	unsigned long *poke = &mcpm_entry_early_pokes[cluster][cpu][0];
+	poke[0] = poke_phys_addr;
+	poke[1] = poke_val;
+	__sync_cache_range_w(poke, 2 * sizeof(*poke));
+}
+
+static const struct mcpm_platform_ops *platform_ops;
+
+int __init mcpm_platform_register(const struct mcpm_platform_ops *ops)
+{
+	if (platform_ops)
+		return -EBUSY;
+	platform_ops = ops;
+	return 0;
+}
+
+bool mcpm_is_available(void)
+{
+	return (platform_ops) ? true : false;
+}
+EXPORT_SYMBOL_GPL(mcpm_is_available);
+
+/*
+ * We can't use regular spinlocks. In the switcher case, it is possible
+ * for an outbound CPU to call power_down() after its inbound counterpart
+ * is already live using the same logical CPU number which trips lockdep
+ * debugging.
+ */
+static arch_spinlock_t mcpm_lock = __ARCH_SPIN_LOCK_UNLOCKED;
+
+static int mcpm_cpu_use_count[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER];
+
+static inline bool mcpm_cluster_unused(unsigned int cluster)
+{
+	int i, cnt;
+	for (i = 0, cnt = 0; i < MAX_CPUS_PER_CLUSTER; i++)
+		cnt |= mcpm_cpu_use_count[cluster][i];
+	return !cnt;
+}
+
+int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster)
+{
+	bool cpu_is_down, cluster_is_down;
+	int ret = 0;
+
+	pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
+	if (!platform_ops)
+		return -EUNATCH; /* try not to shadow power_up errors */
+	might_sleep();
+
+	/*
+	 * Since this is called with IRQs enabled, and no arch_spin_lock_irq
+	 * variant exists, we need to disable IRQs manually here.
+	 */
+	local_irq_disable();
+	arch_spin_lock(&mcpm_lock);
+
+	cpu_is_down = !mcpm_cpu_use_count[cluster][cpu];
+	cluster_is_down = mcpm_cluster_unused(cluster);
+
+	mcpm_cpu_use_count[cluster][cpu]++;
+	/*
+	 * The only possible values are:
+	 * 0 = CPU down
+	 * 1 = CPU (still) up
+	 * 2 = CPU requested to be up before it had a chance
+	 *     to actually make itself down.
+	 * Any other value is a bug.
+	 */
+	BUG_ON(mcpm_cpu_use_count[cluster][cpu] != 1 &&
+	       mcpm_cpu_use_count[cluster][cpu] != 2);
+
+	if (cluster_is_down)
+		ret = platform_ops->cluster_powerup(cluster);
+	if (cpu_is_down && !ret)
+		ret = platform_ops->cpu_powerup(cpu, cluster);
+
+	arch_spin_unlock(&mcpm_lock);
+	local_irq_enable();
+	return ret;
+}
+
+typedef typeof(cpu_reset) phys_reset_t;
+
+void mcpm_cpu_power_down(void)
+{
+	unsigned int mpidr, cpu, cluster;
+	bool cpu_going_down, last_man;
+	phys_reset_t phys_reset;
+
+	mpidr = read_cpuid_mpidr();
+	cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
+	cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
+	pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
+	if (WARN_ON_ONCE(!platform_ops))
+	       return;
+	BUG_ON(!irqs_disabled());
+
+	setup_mm_for_reboot();
+
+	__mcpm_cpu_going_down(cpu, cluster);
+	arch_spin_lock(&mcpm_lock);
+	BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP);
+
+	mcpm_cpu_use_count[cluster][cpu]--;
+	BUG_ON(mcpm_cpu_use_count[cluster][cpu] != 0 &&
+	       mcpm_cpu_use_count[cluster][cpu] != 1);
+	cpu_going_down = !mcpm_cpu_use_count[cluster][cpu];
+	last_man = mcpm_cluster_unused(cluster);
+
+	if (last_man && __mcpm_outbound_enter_critical(cpu, cluster)) {
+		platform_ops->cpu_powerdown_prepare(cpu, cluster);
+		platform_ops->cluster_powerdown_prepare(cluster);
+		arch_spin_unlock(&mcpm_lock);
+		platform_ops->cluster_cache_disable();
+		__mcpm_outbound_leave_critical(cluster, CLUSTER_DOWN);
+	} else {
+		if (cpu_going_down)
+			platform_ops->cpu_powerdown_prepare(cpu, cluster);
+		arch_spin_unlock(&mcpm_lock);
+		/*
+		 * If cpu_going_down is false here, that means a power_up
+		 * request raced ahead of us.  Even if we do not want to
+		 * shut this CPU down, the caller still expects execution
+		 * to return through the system resume entry path, like
+		 * when the WFI is aborted due to a new IRQ or the like..
+		 * So let's continue with cache cleaning in all cases.
+		 */
+		platform_ops->cpu_cache_disable();
+	}
+
+	__mcpm_cpu_down(cpu, cluster);
+
+	/* Now we are prepared for power-down, do it: */
+	if (cpu_going_down)
+		wfi();
+
+	/*
+	 * It is possible for a power_up request to happen concurrently
+	 * with a power_down request for the same CPU. In this case the
+	 * CPU might not be able to actually enter a powered down state
+	 * with the WFI instruction if the power_up request has removed
+	 * the required reset condition.  We must perform a re-entry in
+	 * the kernel as if the power_up method just had deasserted reset
+	 * on the CPU.
+	 */
+	phys_reset = (phys_reset_t)(unsigned long)__pa_symbol(cpu_reset);
+	phys_reset(__pa_symbol(mcpm_entry_point), false);
+
+	/* should never get here */
+	BUG();
+}
+
+int mcpm_wait_for_cpu_powerdown(unsigned int cpu, unsigned int cluster)
+{
+	int ret;
+
+	if (WARN_ON_ONCE(!platform_ops || !platform_ops->wait_for_powerdown))
+		return -EUNATCH;
+
+	ret = platform_ops->wait_for_powerdown(cpu, cluster);
+	if (ret)
+		pr_warn("%s: cpu %u, cluster %u failed to power down (%d)\n",
+			__func__, cpu, cluster, ret);
+
+	return ret;
+}
+
+void mcpm_cpu_suspend(void)
+{
+	if (WARN_ON_ONCE(!platform_ops))
+		return;
+
+	/* Some platforms might have to enable special resume modes, etc. */
+	if (platform_ops->cpu_suspend_prepare) {
+		unsigned int mpidr = read_cpuid_mpidr();
+		unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
+		unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); 
+		arch_spin_lock(&mcpm_lock);
+		platform_ops->cpu_suspend_prepare(cpu, cluster);
+		arch_spin_unlock(&mcpm_lock);
+	}
+	mcpm_cpu_power_down();
+}
+
+int mcpm_cpu_powered_up(void)
+{
+	unsigned int mpidr, cpu, cluster;
+	bool cpu_was_down, first_man;
+	unsigned long flags;
+
+	if (!platform_ops)
+		return -EUNATCH;
+
+	mpidr = read_cpuid_mpidr();
+	cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
+	cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
+	local_irq_save(flags);
+	arch_spin_lock(&mcpm_lock);
+
+	cpu_was_down = !mcpm_cpu_use_count[cluster][cpu];
+	first_man = mcpm_cluster_unused(cluster);
+
+	if (first_man && platform_ops->cluster_is_up)
+		platform_ops->cluster_is_up(cluster);
+	if (cpu_was_down)
+		mcpm_cpu_use_count[cluster][cpu] = 1;
+	if (platform_ops->cpu_is_up)
+		platform_ops->cpu_is_up(cpu, cluster);
+
+	arch_spin_unlock(&mcpm_lock);
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+#ifdef CONFIG_ARM_CPU_SUSPEND
+
+static int __init nocache_trampoline(unsigned long _arg)
+{
+	void (*cache_disable)(void) = (void *)_arg;
+	unsigned int mpidr = read_cpuid_mpidr();
+	unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
+	unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
+	phys_reset_t phys_reset;
+
+	mcpm_set_entry_vector(cpu, cluster, cpu_resume_no_hyp);
+	setup_mm_for_reboot();
+
+	__mcpm_cpu_going_down(cpu, cluster);
+	BUG_ON(!__mcpm_outbound_enter_critical(cpu, cluster));
+	cache_disable();
+	__mcpm_outbound_leave_critical(cluster, CLUSTER_DOWN);
+	__mcpm_cpu_down(cpu, cluster);
+
+	phys_reset = (phys_reset_t)(unsigned long)__pa_symbol(cpu_reset);
+	phys_reset(__pa_symbol(mcpm_entry_point), false);
+	BUG();
+}
+
+int __init mcpm_loopback(void (*cache_disable)(void))
+{
+	int ret;
+
+	/*
+	 * We're going to soft-restart the current CPU through the
+	 * low-level MCPM code by leveraging the suspend/resume
+	 * infrastructure. Let's play it safe by using cpu_pm_enter()
+	 * in case the CPU init code path resets the VFP or similar.
+	 */
+	local_irq_disable();
+	local_fiq_disable();
+	ret = cpu_pm_enter();
+	if (!ret) {
+		ret = cpu_suspend((unsigned long)cache_disable, nocache_trampoline);
+		cpu_pm_exit();
+	}
+	local_fiq_enable();
+	local_irq_enable();
+	if (ret)
+		pr_err("%s returned %d\n", __func__, ret);
+	return ret;
+}
+
+#endif
+
+extern unsigned long mcpm_power_up_setup_phys;
+
+int __init mcpm_sync_init(
+	void (*power_up_setup)(unsigned int affinity_level))
+{
+	unsigned int i, j, mpidr, this_cluster;
+
+	BUILD_BUG_ON(MCPM_SYNC_CLUSTER_SIZE * MAX_NR_CLUSTERS != sizeof mcpm_sync);
+	BUG_ON((unsigned long)&mcpm_sync & (__CACHE_WRITEBACK_GRANULE - 1));
+
+	/*
+	 * Set initial CPU and cluster states.
+	 * Only one cluster is assumed to be active at this point.
+	 */
+	for (i = 0; i < MAX_NR_CLUSTERS; i++) {
+		mcpm_sync.clusters[i].cluster = CLUSTER_DOWN;
+		mcpm_sync.clusters[i].inbound = INBOUND_NOT_COMING_UP;
+		for (j = 0; j < MAX_CPUS_PER_CLUSTER; j++)
+			mcpm_sync.clusters[i].cpus[j].cpu = CPU_DOWN;
+	}
+	mpidr = read_cpuid_mpidr();
+	this_cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
+	for_each_online_cpu(i) {
+		mcpm_cpu_use_count[this_cluster][i] = 1;
+		mcpm_sync.clusters[this_cluster].cpus[i].cpu = CPU_UP;
+	}
+	mcpm_sync.clusters[this_cluster].cluster = CLUSTER_UP;
+	sync_cache_w(&mcpm_sync);
+
+	if (power_up_setup) {
+		mcpm_power_up_setup_phys = __pa_symbol(power_up_setup);
+		sync_cache_w(&mcpm_power_up_setup_phys);
+	}
+
+	return 0;
+}