On Wed, Sep 03 2014 at 11:46 -0600, Lorenzo Pieralisi wrote:
On Wed, Sep 03, 2014 at 06:34:37PM +0100, Lina Iyer wrote:
On Mon, Sep 01 2014 at 09:28 -0600, Lorenzo Pieralisi wrote:
>The CPUidle subsystem on ARM64 machines requires the idle states
>implementation back-end to initialize idle states parameter upon
>boot. This patch adds a hook in the CPU operations structure that
>should be initialized by the CPU operations back-end in order to
>provide a function that initializes cpu idle states.
>
>This patch also adds the infrastructure to arm64 kernel required
>to export the CPU operations based initialization interface, so
>that drivers (ie CPUidle) can use it when they are initialized
>at probe time.
>
I like the change for ARM64.
However, that raises a question, how do I have the same driver that
should get probed by a platform device (on 32 bit ARM) and getting called
from cpu_init_idle on ARM64?
I am not following you sorry. The ARM64 CPUidle driver calls the arm64
cpu_init_idle hooks to initialize idle states (in a generic way from
a driver perspective), not the other way around.
On ARM64 your idle driver rely on an arm64 suspend back-end (eg PSCI) to
enter idle states, it works in a different way from ARM, on purpose.
Have a look at what the code does, it won't be the same driver that's
for certain, since on arm64 I do not want to cope with per-platform
CPUidle state enter functions anymore, the arm64 cpu_ops suspend hook
implements the idle state enter method.
Ah, I was working on the premise that I may be using the same cpuidle
driver for ARM64. I guess I will worry about ARM64 with non-PSCI drivers
when and if I have to. Thanks!
Lorenzo
>Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
>Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
>---
> arch/arm64/include/asm/cpu_ops.h | 3 +++
> arch/arm64/include/asm/cpuidle.h | 13 +++++++++++++
> arch/arm64/kernel/Makefile | 1 +
> arch/arm64/kernel/cpuidle.c | 31 +++++++++++++++++++++++++++++++
> 4 files changed, 48 insertions(+)
> create mode 100644 arch/arm64/include/asm/cpuidle.h
> create mode 100644 arch/arm64/kernel/cpuidle.c
>
>diff --git a/arch/arm64/include/asm/cpu_ops.h b/arch/arm64/include/asm/cpu_ops.h
>index d7b4b38..47dfa31 100644
>--- a/arch/arm64/include/asm/cpu_ops.h
>+++ b/arch/arm64/include/asm/cpu_ops.h
>@@ -28,6 +28,8 @@ struct device_node;
> * enable-method property.
> * @cpu_init: Reads any data necessary for a specific enable-method from the
> * devicetree, for a given cpu node and proposed logical id.
>+ * @cpu_init_idle: Reads any data necessary to initialize CPU idle states from
>+ * devicetree, for a given cpu node and proposed logical id.
> * @cpu_prepare: Early one-time preparation step for a cpu. If there is a
> * mechanism for doing so, tests whether it is possible to boot
> * the given CPU.
>@@ -47,6 +49,7 @@ struct device_node;
> struct cpu_operations {
> const char *name;
> int (*cpu_init)(struct device_node *, unsigned int);
>+ int (*cpu_init_idle)(struct device_node *, unsigned int);
> int (*cpu_prepare)(unsigned int);
> int (*cpu_boot)(unsigned int);
> void (*cpu_postboot)(void);
>diff --git a/arch/arm64/include/asm/cpuidle.h b/arch/arm64/include/asm/cpuidle.h
>new file mode 100644
>index 0000000..b52a993
>--- /dev/null
>+++ b/arch/arm64/include/asm/cpuidle.h
>@@ -0,0 +1,13 @@
>+#ifndef __ASM_CPUIDLE_H
>+#define __ASM_CPUIDLE_H
>+
>+#ifdef CONFIG_CPU_IDLE
>+extern int cpu_init_idle(unsigned int cpu);
>+#else
>+static inline int cpu_init_idle(unsigned int cpu)
>+{
>+ return -EOPNOTSUPP;
>+}
>+#endif
>+
>+#endif
>diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
>index 383d81d..be78980 100644
>--- a/arch/arm64/kernel/Makefile
>+++ b/arch/arm64/kernel/Makefile
>@@ -27,6 +27,7 @@ arm64-obj-$(CONFIG_PERF_EVENTS) += perf_regs.o
> arm64-obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o
> arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
> arm64-obj-$(CONFIG_ARM64_CPU_SUSPEND) += sleep.o suspend.o
>+arm64-obj-$(CONFIG_CPU_IDLE) += cpuidle.o
> arm64-obj-$(CONFIG_JUMP_LABEL) += jump_label.o
> arm64-obj-$(CONFIG_KGDB) += kgdb.o
> arm64-obj-$(CONFIG_EFI) += efi.o efi-stub.o efi-entry.o
>diff --git a/arch/arm64/kernel/cpuidle.c b/arch/arm64/kernel/cpuidle.c
>new file mode 100644
>index 0000000..19d17f5
>--- /dev/null
>+++ b/arch/arm64/kernel/cpuidle.c
>@@ -0,0 +1,31 @@
>+/*
>+ * ARM64 CPU idle arch support
>+ *
>+ * Copyright (C) 2014 ARM Ltd.
>+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
>+ *
>+ * 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/of.h>
>+#include <linux/of_device.h>
>+
>+#include <asm/cpuidle.h>
>+#include <asm/cpu_ops.h>
>+
>+int cpu_init_idle(unsigned int cpu)
>+{
>+ int ret = -EOPNOTSUPP;
>+ struct device_node *cpu_node = of_cpu_device_node_get(cpu);
>+
>+ if (!cpu_node)
>+ return -ENODEV;
>+
>+ if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_init_idle)
>+ ret = cpu_ops[cpu]->cpu_init_idle(cpu_node, cpu);
>+
>+ of_node_put(cpu_node);
>+ return ret;
>+}
>--
>1.9.1
>
>
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