[PATCH 3/4] ARM: vexpress/TC2: basic PM support
Nicolas Pitre
nicolas.pitre at linaro.org
Wed Jul 17 23:28:35 EDT 2013
This is the MCPM backend for the Virtual Express A15x2 A7x3 CoreTile
aka TC2. This provides cluster management for SMP secondary boot and
CPU hotplug.
Signed-off-by: Nicolas Pitre <nico at linaro.org>
Acked-by: Pawel Moll <pawel.moll at arm.com>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
---
arch/arm/mach-vexpress/Kconfig | 9 ++
arch/arm/mach-vexpress/Makefile | 1 +
arch/arm/mach-vexpress/tc2_pm.c | 287 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 297 insertions(+)
create mode 100644 arch/arm/mach-vexpress/tc2_pm.c
diff --git a/arch/arm/mach-vexpress/Kconfig b/arch/arm/mach-vexpress/Kconfig
index b8bbabec63..4b082f8912 100644
--- a/arch/arm/mach-vexpress/Kconfig
+++ b/arch/arm/mach-vexpress/Kconfig
@@ -66,4 +66,13 @@ config ARCH_VEXPRESS_DCSCB
This is needed to provide CPU and cluster power management
on RTSM implementing big.LITTLE.
+config ARCH_VEXPRESS_TC2_PM
+ bool "Versatile Express TC2 power management"
+ depends on MCPM
+ select VEXPRESS_SPC
+ select ARM_CCI
+ help
+ Support for CPU and cluster power management on Versatile Express
+ with a TC2 (A15x2 A7x3) big.LITTLE core tile.
+
endmenu
diff --git a/arch/arm/mach-vexpress/Makefile b/arch/arm/mach-vexpress/Makefile
index 48ba89a814..0853da6395 100644
--- a/arch/arm/mach-vexpress/Makefile
+++ b/arch/arm/mach-vexpress/Makefile
@@ -7,5 +7,6 @@ ccflags-$(CONFIG_ARCH_MULTIPLATFORM) := -I$(srctree)/$(src)/include \
obj-y := v2m.o
obj-$(CONFIG_ARCH_VEXPRESS_CA9X4) += ct-ca9x4.o
obj-$(CONFIG_ARCH_VEXPRESS_DCSCB) += dcscb.o dcscb_setup.o
+obj-$(CONFIG_ARCH_VEXPRESS_TC2_PM) += tc2_pm.o
obj-$(CONFIG_SMP) += platsmp.o
obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
diff --git a/arch/arm/mach-vexpress/tc2_pm.c b/arch/arm/mach-vexpress/tc2_pm.c
new file mode 100644
index 0000000000..26dbe782fb
--- /dev/null
+++ b/arch/arm/mach-vexpress/tc2_pm.c
@@ -0,0 +1,287 @@
+/*
+ * arch/arm/mach-vexpress/tc2_pm.c - TC2 power management support
+ *
+ * Created by: Nicolas Pitre, October 2012
+ * Copyright: (C) 2012-2013 Linaro Limited
+ *
+ * Some portions of this file were originally written by Achin Gupta
+ * Copyright: (C) 2012 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/errno.h>
+
+#include <asm/mcpm.h>
+#include <asm/proc-fns.h>
+#include <asm/cacheflush.h>
+#include <asm/cputype.h>
+#include <asm/cp15.h>
+
+#include <linux/vexpress.h>
+#include <linux/arm-cci.h>
+
+/*
+ * 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 tc2_pm_lock = __ARCH_SPIN_LOCK_UNLOCKED;
+
+#define TC2_CLUSTERS 2
+#define TC2_MAX_CPUS_PER_CLUSTER 3
+
+/* Keep per-cpu usage count to cope with unordered up/down requests */
+static int tc2_pm_use_count[TC2_MAX_CPUS_PER_CLUSTER][TC2_CLUSTERS];
+
+#define tc2_cluster_unused(cluster) \
+ (!tc2_pm_use_count[0][cluster] && \
+ !tc2_pm_use_count[1][cluster] && \
+ !tc2_pm_use_count[2][cluster])
+
+static int tc2_pm_power_up(unsigned int cpu, unsigned int cluster)
+{
+ pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);
+ if (cluster >= TC2_CLUSTERS || cpu >= ve_spc_get_nr_cpus(cluster))
+ return -EINVAL;
+
+ /*
+ * 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(&tc2_pm_lock);
+
+ if (tc2_cluster_unused(cluster))
+ ve_spc_powerdown(cluster, false);
+
+ tc2_pm_use_count[cpu][cluster]++;
+ if (tc2_pm_use_count[cpu][cluster] == 1) {
+ ve_spc_set_resume_addr(cluster, cpu,
+ virt_to_phys(mcpm_entry_point));
+ ve_spc_cpu_wakeup_irq(cluster, cpu, true);
+ } else if (tc2_pm_use_count[cpu][cluster] != 2) {
+ /*
+ * 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();
+ }
+
+ arch_spin_unlock(&tc2_pm_lock);
+ local_irq_enable();
+
+ return 0;
+}
+
+static void tc2_pm_power_down(void)
+{
+ unsigned int mpidr, cpu, cluster;
+ bool last_man = false, skip_wfi = false;
+
+ 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);
+ BUG_ON(cluster >= TC2_CLUSTERS || cpu >= TC2_MAX_CPUS_PER_CLUSTER);
+
+ __mcpm_cpu_going_down(cpu, cluster);
+
+ arch_spin_lock(&tc2_pm_lock);
+ BUG_ON(__mcpm_cluster_state(cluster) != CLUSTER_UP);
+ tc2_pm_use_count[cpu][cluster]--;
+ if (tc2_pm_use_count[cpu][cluster] == 0) {
+ ve_spc_cpu_wakeup_irq(cluster, cpu, true);
+ if (tc2_cluster_unused(cluster)) {
+ ve_spc_powerdown(cluster, true);
+ ve_spc_global_wakeup_irq(true);
+ last_man = true;
+ }
+ } else if (tc2_pm_use_count[cpu][cluster] == 1) {
+ /*
+ * A power_up request went ahead of us.
+ * Even if we do not want to shut this CPU down,
+ * the caller expects a certain state as if the WFI
+ * was aborted. So let's continue with cache cleaning.
+ */
+ skip_wfi = true;
+ } else
+ BUG();
+
+ if (last_man && __mcpm_outbound_enter_critical(cpu, cluster)) {
+ arch_spin_unlock(&tc2_pm_lock);
+
+ if (read_cpuid_part_number() == ARM_CPU_PART_CORTEX_A15) {
+ /*
+ * On the Cortex-A15 we need to disable
+ * L2 prefetching before flushing the cache.
+ */
+ asm volatile(
+ "mcr p15, 1, %0, c15, c0, 3 \n\t"
+ "isb \n\t"
+ "dsb "
+ : : "r" (0x400) );
+ }
+
+ /*
+ * We need to disable and flush the whole (L1 and L2) cache.
+ * Let's do it in the safest possible way i.e. with
+ * no memory access within the following sequence
+ * including the stack.
+ */
+ asm volatile(
+ "mrc p15, 0, r0, c1, c0, 0 @ get CR \n\t"
+ "bic r0, r0, #"__stringify(CR_C)" \n\t"
+ "mcr p15, 0, r0, c1, c0, 0 @ set CR \n\t"
+ "isb \n\t"
+ "bl v7_flush_dcache_all \n\t"
+ "clrex \n\t"
+ "mrc p15, 0, r0, c1, c0, 1 @ get AUXCR \n\t"
+ "bic r0, r0, #(1 << 6) @ disable local coherency \n\t"
+ "mcr p15, 0, r0, c1, c0, 1 @ set AUXCR \n\t"
+ "isb \n\t"
+ "dsb "
+ : : : "r0","r1","r2","r3","r4","r5","r6","r7",
+ "r9","r10","r11","lr","memory");
+
+ cci_disable_port_by_cpu(mpidr);
+
+ __mcpm_outbound_leave_critical(cluster, CLUSTER_DOWN);
+ } else {
+ /*
+ * If last man then undo any setup done previously.
+ */
+ if (last_man) {
+ ve_spc_powerdown(cluster, false);
+ ve_spc_global_wakeup_irq(false);
+ }
+
+ arch_spin_unlock(&tc2_pm_lock);
+
+ /*
+ * We need to disable and flush only the L1 cache.
+ * Let's do it in the safest possible way as above.
+ */
+ asm volatile(
+ "mrc p15, 0, r0, c1, c0, 0 @ get CR \n\t"
+ "bic r0, r0, #"__stringify(CR_C)" \n\t"
+ "mcr p15, 0, r0, c1, c0, 0 @ set CR \n\t"
+ "isb \n\t"
+ "bl v7_flush_dcache_louis \n\t"
+ "clrex \n\t"
+ "mrc p15, 0, r0, c1, c0, 1 @ get AUXCR \n\t"
+ "bic r0, r0, #(1 << 6) @ disable local coherency \n\t"
+ "mcr p15, 0, r0, c1, c0, 1 @ set AUXCR \n\t"
+ "isb \n\t"
+ "dsb "
+ : : : "r0","r1","r2","r3","r4","r5","r6","r7",
+ "r9","r10","r11","lr","memory");
+ }
+
+ __mcpm_cpu_down(cpu, cluster);
+
+ /* Now we are prepared for power-down, do it: */
+ if (!skip_wfi)
+ wfi();
+
+ /* Not dead at this point? Let our caller cope. */
+}
+
+static void tc2_pm_powered_up(void)
+{
+ unsigned int mpidr, cpu, cluster;
+ unsigned long flags;
+
+ 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);
+ BUG_ON(cluster >= TC2_CLUSTERS || cpu >= TC2_MAX_CPUS_PER_CLUSTER);
+
+ local_irq_save(flags);
+ arch_spin_lock(&tc2_pm_lock);
+
+ if (tc2_cluster_unused(cluster)) {
+ ve_spc_powerdown(cluster, false);
+ ve_spc_global_wakeup_irq(false);
+ }
+
+ if (!tc2_pm_use_count[cpu][cluster])
+ tc2_pm_use_count[cpu][cluster] = 1;
+
+ ve_spc_cpu_wakeup_irq(cluster, cpu, false);
+ ve_spc_set_resume_addr(cluster, cpu, 0);
+
+ arch_spin_unlock(&tc2_pm_lock);
+ local_irq_restore(flags);
+}
+
+static const struct mcpm_platform_ops tc2_pm_power_ops = {
+ .power_up = tc2_pm_power_up,
+ .power_down = tc2_pm_power_down,
+ .powered_up = tc2_pm_powered_up,
+};
+
+static bool __init tc2_pm_usage_count_init(void)
+{
+ unsigned int mpidr, cpu, cluster;
+
+ 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 (cluster >= TC2_CLUSTERS || cpu >= ve_spc_get_nr_cpus(cluster)) {
+ pr_err("%s: boot CPU is out of bound!\n", __func__);
+ return false;
+ }
+ tc2_pm_use_count[cpu][cluster] = 1;
+ return true;
+}
+
+/*
+ * Enable cluster-level coherency, in preparation for turning on the MMU.
+ */
+static void __naked tc2_pm_power_up_setup(unsigned int affinity_level)
+{
+ asm volatile (" \n"
+" cmp r0, #1 \n"
+" bxne lr \n"
+" b cci_enable_port_for_self ");
+}
+
+static int __init tc2_pm_init(void)
+{
+ int ret;
+
+ ret = ve_spc_init();
+ if (ret)
+ return ret;
+
+ if (!cci_probed())
+ return -ENODEV;
+
+ if (!tc2_pm_usage_count_init())
+ return -EINVAL;
+
+ ret = mcpm_platform_register(&tc2_pm_power_ops);
+ if (!ret) {
+ mcpm_sync_init(tc2_pm_power_up_setup);
+ pr_info("TC2 power management initialized\n");
+ }
+ return ret;
+}
+
+early_initcall(tc2_pm_init);
--
1.8.1.2
More information about the linux-arm-kernel
mailing list