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authorAchin Gupta <achin.gupta@arm.com>2013-02-26 15:33:25 +0000
committerJon Medhurst <tixy@linaro.org>2013-05-03 13:50:07 +0100
commit7fbc765bf7225910d4a0e04173ec378add122634 (patch)
tree28de541bf9f0b6d4093db4d7f0111381411d5d47
parent6724719f02a04223c2223914f30821e191d9a064 (diff)
downloadvexpress-lsk-7fbc765bf7225910d4a0e04173ec378add122634.tar.gz
ARM: vexpress: add shim layer for psci backend on TC2
This patch introduces a shim layer for the TC2 platform which converts 'bL_platform_power_ops' routines to their psci counterparts. The psci counterparts are implemented by the secure firmware. The shim layer is used only when Linux is running in non-secure world and the secure firmware implements psci. It also introduces the use of a reference count to allow a power up call to go ahead of a power down call. Signed-off-by: Achin Gupta <achin.gupta@arm.com> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
-rw-r--r--arch/arm/mach-vexpress/Makefile4
-rw-r--r--arch/arm/mach-vexpress/tc2_pm_psci.c179
2 files changed, 183 insertions, 0 deletions
diff --git a/arch/arm/mach-vexpress/Makefile b/arch/arm/mach-vexpress/Makefile
index a95282125eb..4dbc5891275 100644
--- a/arch/arm/mach-vexpress/Makefile
+++ b/arch/arm/mach-vexpress/Makefile
@@ -8,5 +8,9 @@ obj-y := v2m.o reset.o
obj-$(CONFIG_ARCH_VEXPRESS_CA9X4) += ct-ca9x4.o
obj-$(CONFIG_ARCH_VEXPRESS_TC2) += tc2_pm.o tc2_pm_setup.o
CFLAGS_REMOVE_tc2_pm.o = -pg
+ifeq ($(CONFIG_ARCH_VEXPRESS_TC2),y)
+obj-$(CONFIG_ARM_PSCI) += tc2_pm_psci.o
+CFLAGS_REMOVE_tc2_pm_psci.o = -pg
+endif
obj-$(CONFIG_SMP) += platsmp.o
obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
diff --git a/arch/arm/mach-vexpress/tc2_pm_psci.c b/arch/arm/mach-vexpress/tc2_pm_psci.c
new file mode 100644
index 00000000000..c9715b8137e
--- /dev/null
+++ b/arch/arm/mach-vexpress/tc2_pm_psci.c
@@ -0,0 +1,179 @@
+/*
+ * arch/arm/mach-vexpress/tc2_pm_psci.c - TC2 PSCI support
+ *
+ * Created by: Achin Gupta, December 2012
+ * Copyright: (C) 2012 ARM Limited
+ *
+ * Some portions of this file were originally written by Nicolas Pitre
+ * Copyright: (C) 2012 Linaro 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/bL_entry.h>
+#include <asm/proc-fns.h>
+#include <asm/cacheflush.h>
+#include <asm/psci.h>
+#include <asm/atomic.h>
+#include <asm/cputype.h>
+
+#include <mach/motherboard.h>
+#include <mach/tc2.h>
+
+#include <linux/vexpress.h>
+
+/*
+ * Platform specific state id understood by the firmware and used to
+ * program the power controller
+ */
+#define PSCI_POWER_STATE_ID 0
+
+static atomic_t tc2_pm_use_count[TC2_MAX_CPUS][TC2_MAX_CLUSTERS];
+
+static int tc2_pm_psci_power_up(unsigned int cpu, unsigned int cluster)
+{
+ unsigned int mpidr = (cluster << 8) | cpu;
+ int ret = 0;
+
+ BUG_ON(!psci_ops.cpu_on);
+
+ switch (atomic_inc_return(&tc2_pm_use_count[cpu][cluster])) {
+ case 1:
+ /*
+ * This is a request to power up a cpu that linux thinks has
+ * been powered down. Retries are needed if the firmware has
+ * seen the power down request as yet.
+ */
+ do
+ ret = psci_ops.cpu_on(mpidr,
+ virt_to_phys(bL_entry_point));
+ while (ret == -EAGAIN);
+
+ return ret;
+ case 2:
+ /* This power up request has overtaken a power down request */
+ return ret;
+ default:
+ /* Any other value is a bug */
+ BUG();
+ }
+}
+
+static void tc2_pm_psci_power_down(void)
+{
+ struct psci_power_state power_state;
+ unsigned int mpidr, cpu, cluster;
+
+ mpidr = read_cpuid_mpidr();
+ cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
+ cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
+
+ BUG_ON(!psci_ops.cpu_off);
+
+ switch (atomic_dec_return(&tc2_pm_use_count[cpu][cluster])) {
+ case 1:
+ /*
+ * Overtaken by a power up. Flush caches, exit coherency,
+ * return & fake a reset
+ */
+ asm volatile (
+ "mrc p15, 0, ip, c1, c0, 0 \n\t"
+ "bic ip, ip, #(1 << 2) @ clear C bit \n\t"
+ "mcr p15, 0, ip, c1, c0, 0 \n\t"
+ "dsb \n\t"
+ "isb"
+ : : : "ip" );
+
+ flush_cache_louis();
+
+ asm volatile (
+ "clrex \n\t"
+ "mrc p15, 0, ip, c1, c0, 1 \n\t"
+ "bic ip, ip, #(1 << 6) @ clear SMP bit \n\t"
+ "mcr p15, 0, ip, c1, c0, 1 \n\t"
+ "isb \n\t"
+ "dsb"
+ : : : "ip" );
+
+ return;
+ case 0:
+ /* A normal request to possibly power down the cluster */
+ power_state.id = PSCI_POWER_STATE_ID;
+ power_state.type = PSCI_POWER_STATE_TYPE_POWER_DOWN;
+ power_state.affinity_level = PSCI_POWER_STATE_AFFINITY_LEVEL1;
+
+ psci_ops.cpu_off(power_state);
+
+ /* On success this function never returns */
+ default:
+ /* Any other value is a bug */
+ BUG();
+ }
+}
+
+static void tc2_pm_psci_suspend(u64 unused)
+{
+ struct psci_power_state power_state;
+
+ BUG_ON(!psci_ops.cpu_suspend);
+
+ /* On TC2 always attempt to power down the cluster */
+ power_state.id = PSCI_POWER_STATE_ID;
+ power_state.type = PSCI_POWER_STATE_TYPE_POWER_DOWN;
+ power_state.affinity_level = PSCI_POWER_STATE_AFFINITY_LEVEL1;
+
+ psci_ops.cpu_suspend(power_state, virt_to_phys(bL_entry_point));
+
+ /* On success this function never returns */
+ BUG();
+}
+
+static const struct bL_platform_power_ops tc2_pm_power_ops = {
+ .power_up = tc2_pm_psci_power_up,
+ .power_down = tc2_pm_psci_power_down,
+ .suspend = tc2_pm_psci_suspend,
+};
+
+static void __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);
+ BUG_ON(cluster >= TC2_MAX_CLUSTERS ||
+ cpu >= vexpress_spc_get_nb_cpus(cluster));
+
+ atomic_set(&tc2_pm_use_count[cpu][cluster], 1);
+}
+
+static int __init tc2_pm_psci_init(void)
+{
+ int ret;
+
+ ret = psci_probe();
+ if (ret) {
+ pr_debug("psci not found. Aborting psci init\n");
+ return -ENODEV;
+ }
+
+ tc2_pm_usage_count_init();
+
+ ret = bL_platform_power_register(&tc2_pm_power_ops);
+ if (!ret)
+ ret = bL_cluster_sync_init(NULL);
+ if (!ret)
+ pr_info("TC2 power management initialized\n");
+ return ret;
+}
+
+early_initcall(tc2_pm_psci_init);