[PATCH RFC v2 0/4] ARM generic idle states

[PATCH RFC v2 0/4] ARM generic idle states

[Lorenzo Pieralisi]

This patchset is v2 of a previous posting:

http://www.spinics.net/lists/arm-kernel/msg316263.html

Changes in v2:

- Moved OF parsing code to drivers/cpuidle
- Improved states detection and sorting through linked list
- Split code in generic and ARM64 specific bits
- Moved idle enter function into ARM64 idle driver
- Refactored PSCI idle states register function
- Renamed suspend operations and moved detection to ARM64 idle driver
- Changed the way CPUIDLE_FLAG_TIMER_STOP is handled
- Simplified idle state nodes parsing since according to the latest
  bindings idle state nodes are a flat list, not hierarchical anymore
- Used min-residency-us to sort the states, to be further discussed

Idle states on most ARM platforms can be characterized by a set of
parameters that are platform agnostic and describe the HW idle states
features. So far, CPU idle drivers for ARM platforms required the definition
of parameters through static tables, duplicating control data for different
platforms. Moreover, the lack of standardization on firmware interfaces
hampered any standardization effort, resulting in CPU idle drivers for ARM
platforms containing duplicated code and platform specific power down routines.

The introduction of the PSCI firmware interface, and more in general, well
defined suspend back-ends, allows the definition of generic idle states and
the respective kernel infrastructure to support them.

Building on top of DT idle states bindings[1], that standardize idle states
parameters and corresponding suspend back-ends, this patchset provides code
that parses DT idle states nodes and builds at run-time the control data
infrastructure required by the ARM CPU idle drivers.

Idle states define an entry method (eg PSCI), that requires the respective
ARM64 kernel back-end to be invoked to initialize idle states parameters, so
that when the idle driver executes the back-end specific entry method a table
look-up can be carried out to retrieve the corresponding idle state parameter.

On legacy ARM platforms, the OF idle states are just used to initialize
states data.

The idle states bindings can be extended with new back-ends; the ARM64 CPUidle
driver must be updated accordingly so that the corresponding back
end initializer can be invoked at boot time for parameters initialization.

Patchset has been tested on AEM v8 models, on top of bootwrapper PSCI CPU
SUSPEND implementation which provides simulated core power gating.

[1] http://www.spinics.net/lists/arm-kernel/msg316299.html

Lorenzo Pieralisi (4):
  drivers: cpuidle: implement OF based idle states infrastructure
  arm64: add PSCI CPU_SUSPEND based cpu_suspend support
  drivers: cpuidle: CPU idle ARM64 driver
  arm64: boot: dts: update rtsm aemv8 dts with PSCI and idle states

 arch/arm64/boot/dts/rtsm_ve-aemv8a.dts |  49 +++++-
 arch/arm64/include/asm/psci.h          |   4 +
 arch/arm64/kernel/psci.c               | 102 ++++++++++++
 drivers/cpuidle/Kconfig                |  14 ++
 drivers/cpuidle/Kconfig.arm64          |  13 ++
 drivers/cpuidle/Makefile               |   5 +
 drivers/cpuidle/cpuidle-arm64.c        | 159 +++++++++++++++++++
 drivers/cpuidle/of_idle_states.c       | 274 +++++++++++++++++++++++++++++++++
 drivers/cpuidle/of_idle_states.h       |   8 +
 9 files changed, 620 insertions(+), 8 deletions(-)
 create mode 100644 drivers/cpuidle/Kconfig.arm64
 create mode 100644 drivers/cpuidle/cpuidle-arm64.c
 create mode 100644 drivers/cpuidle/of_idle_states.c
 create mode 100644 drivers/cpuidle/of_idle_states.h

-- 
1.8.4

[PATCH RFC v2 0/4] ARM generic idle states

[Lorenzo Pieralisi]

This patchset is v2 of a previous posting:

http://www.spinics.net/lists/arm-kernel/msg316263.html

Changes in v2:

- Moved OF parsing code to drivers/cpuidle
- Improved states detection and sorting through linked list
- Split code in generic and ARM64 specific bits
- Moved idle enter function into ARM64 idle driver
- Refactored PSCI idle states register function
- Renamed suspend operations and moved detection to ARM64 idle driver
- Changed the way CPUIDLE_FLAG_TIMER_STOP is handled
- Simplified idle state nodes parsing since according to the latest
  bindings idle state nodes are a flat list, not hierarchical anymore
- Used min-residency-us to sort the states, to be further discussed

Idle states on most ARM platforms can be characterized by a set of
parameters that are platform agnostic and describe the HW idle states
features. So far, CPU idle drivers for ARM platforms required the definition
of parameters through static tables, duplicating control data for different
platforms. Moreover, the lack of standardization on firmware interfaces
hampered any standardization effort, resulting in CPU idle drivers for ARM
platforms containing duplicated code and platform specific power down routines.

The introduction of the PSCI firmware interface, and more in general, well
defined suspend back-ends, allows the definition of generic idle states and
the respective kernel infrastructure to support them.

Building on top of DT idle states bindings[1], that standardize idle states
parameters and corresponding suspend back-ends, this patchset provides code
that parses DT idle states nodes and builds at run-time the control data
infrastructure required by the ARM CPU idle drivers.

Idle states define an entry method (eg PSCI), that requires the respective
ARM64 kernel back-end to be invoked to initialize idle states parameters, so
that when the idle driver executes the back-end specific entry method a table
look-up can be carried out to retrieve the corresponding idle state parameter.

On legacy ARM platforms, the OF idle states are just used to initialize
states data.

The idle states bindings can be extended with new back-ends; the ARM64 CPUidle
driver must be updated accordingly so that the corresponding back
end initializer can be invoked at boot time for parameters initialization.

Patchset has been tested on AEM v8 models, on top of bootwrapper PSCI CPU
SUSPEND implementation which provides simulated core power gating.

[1] http://www.spinics.net/lists/arm-kernel/msg316299.html

Lorenzo Pieralisi (4):
  drivers: cpuidle: implement OF based idle states infrastructure
  arm64: add PSCI CPU_SUSPEND based cpu_suspend support
  drivers: cpuidle: CPU idle ARM64 driver
  arm64: boot: dts: update rtsm aemv8 dts with PSCI and idle states

 arch/arm64/boot/dts/rtsm_ve-aemv8a.dts |  49 +++++-
 arch/arm64/include/asm/psci.h          |   4 +
 arch/arm64/kernel/psci.c               | 102 ++++++++++++
 drivers/cpuidle/Kconfig                |  14 ++
 drivers/cpuidle/Kconfig.arm64          |  13 ++
 drivers/cpuidle/Makefile               |   5 +
 drivers/cpuidle/cpuidle-arm64.c        | 159 +++++++++++++++++++
 drivers/cpuidle/of_idle_states.c       | 274 +++++++++++++++++++++++++++++++++
 drivers/cpuidle/of_idle_states.h       |   8 +
 9 files changed, 620 insertions(+), 8 deletions(-)
 create mode 100644 drivers/cpuidle/Kconfig.arm64
 create mode 100644 drivers/cpuidle/cpuidle-arm64.c
 create mode 100644 drivers/cpuidle/of_idle_states.c
 create mode 100644 drivers/cpuidle/of_idle_states.h

-- 
1.8.4

[PATCH RFC v2 1/4] drivers: cpuidle: implement OF based idle states infrastructure

[Lorenzo Pieralisi]

On most common ARM systems, the low-power states a CPU can be put into are
not discoverable in HW and require device tree bindings to describe
the respective power domains, power down protocol and idle states parameters.

In order to enable DT based idle states and configure idle drivers, this
patch implements the bulk infrastructure required to parse the device tree
idle states bindings and initialize the corresponding CPUidle driver states
data.

Code that initializes idle states checks the CPU idle driver cpumask so
that multiple CPU idle drivers can be initialized through it in the
kernel. The CPU idle driver cpumask defines which idle states should be
considered valid for the driver, ie idle states that are valid on a set
of cpus the idle driver manages.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
 drivers/cpuidle/Kconfig          |   9 ++
 drivers/cpuidle/Makefile         |   1 +
 drivers/cpuidle/of_idle_states.c | 274 +++++++++++++++++++++++++++++++++++++++
 drivers/cpuidle/of_idle_states.h |   8 ++
 4 files changed, 292 insertions(+)
 create mode 100644 drivers/cpuidle/of_idle_states.c
 create mode 100644 drivers/cpuidle/of_idle_states.h

diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index f04e25f..995654e 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -30,6 +30,15 @@ config CPU_IDLE_GOV_MENU
 	bool "Menu governor (for tickless system)"
 	default y
 
+config OF_IDLE_STATES
+        bool "Idle states DT support"
+	depends on ARM || ARM64
+	default n
+	help
+	 Allows the CPU idle framework to initialize CPU idle drivers
+	 state data by using DT provided nodes compliant with idle states
+	 device tree bindings.
+
 menu "ARM CPU Idle Drivers"
 depends on ARM
 source "drivers/cpuidle/Kconfig.arm"
diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index f71ae1b..2fc5139 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -4,6 +4,7 @@
 
 obj-y += cpuidle.o driver.o governor.o sysfs.o governors/
 obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
+obj-$(CONFIG_OF_IDLE_STATES)		  += of_idle_states.o
 
 ##################################################################################
 # ARM SoC drivers
diff --git a/drivers/cpuidle/of_idle_states.c b/drivers/cpuidle/of_idle_states.c
new file mode 100644
index 0000000..eceb1b4
--- /dev/null
+++ b/drivers/cpuidle/of_idle_states.c
@@ -0,0 +1,274 @@
+/*
+ * OF idle states parsing code.
+ *
+ * Copyright (C) 2014 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+ *
+ * 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/cpuidle.h>
+#include <linux/cpumask.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/list_sort.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+#include "of_idle_states.h"
+
+struct state_elem {
+	struct list_head list;
+	struct device_node *node;
+	int val;
+};
+
+static struct list_head head __initdata = LIST_HEAD_INIT(head);
+
+static bool __init state_cpu_valid(struct device_node *state_node,
+				   struct device_node *cpu_node)
+{
+	int i = 0;
+	struct device_node *cpu_state;
+
+	while ((cpu_state = of_parse_phandle(cpu_node,
+					     "cpu-idle-states", i++))) {
+		if (cpu_state && state_node == cpu_state) {
+			of_node_put(cpu_state);
+			return true;
+		}
+		of_node_put(cpu_state);
+	}
+	return false;
+}
+
+static bool __init state_cpus_valid(const cpumask_t *cpus,
+				    struct device_node *state_node)
+{
+	int cpu;
+	struct device_node *cpu_node;
+
+	/*
+	 * Check if state is valid on driver cpumask cpus
+	 */
+	for_each_cpu(cpu, cpus) {
+		cpu_node = of_get_cpu_node(cpu, NULL);
+
+		if (!cpu_node) {
+			pr_err("Missing device node for CPU %d\n", cpu);
+			return false;
+		}
+
+		if (!state_cpu_valid(state_node, cpu_node))
+			return false;
+	}
+
+	return true;
+}
+
+static int __init state_cmp(void *priv, struct list_head *a,
+			    struct list_head *b)
+{
+	struct state_elem *ela, *elb;
+
+	ela = container_of(a, struct state_elem, list);
+	elb = container_of(b, struct state_elem, list);
+
+	return ela->val - elb->val;
+}
+
+static int __init add_state_node(cpumask_t *cpumask,
+				 struct device_node *state_node)
+{
+	struct state_elem *el;
+	u32 val;
+
+	pr_debug(" * %s...\n", state_node->full_name);
+
+	if (!state_cpus_valid(cpumask, state_node))
+		return -EINVAL;
+	/*
+	 * Parse just the value required to sort the states.
+	 */
+	if (of_property_read_u32(state_node, "min-residency-us",
+				 &val)) {
+		pr_debug(" * %s missing min-residency-us property\n",
+			 state_node->full_name);
+		return -EINVAL;
+	}
+
+	el = kmalloc(sizeof(*el), GFP_KERNEL);
+	if (!el) {
+		pr_err("%s failed to allocate memory\n", __func__);
+		return -ENOMEM;
+	}
+
+	el->node = state_node;
+	el->val = val;
+	list_add_tail(&el->list, &head);
+
+	return 0;
+}
+
+static void __init init_state_node(struct cpuidle_driver *drv,
+				   struct device_node *state_node,
+				   int *cnt)
+{
+	struct cpuidle_state *idle_state;
+
+	pr_debug(" * %s...\n", state_node->full_name);
+
+	idle_state = &drv->states[*cnt];
+
+	if (of_property_read_u32(state_node, "exit-latency-us",
+				 &idle_state->exit_latency)) {
+		pr_debug(" * %s missing exit-latency-us property\n",
+			     state_node->full_name);
+		return;
+	}
+
+	if (of_property_read_u32(state_node, "min-residency-us",
+				 &idle_state->target_residency)) {
+		pr_debug(" * %s missing min-residency-us property\n",
+			     state_node->full_name);
+		return;
+	}
+	/*
+	 * It is unknown to the idle driver if and when the tick_device
+	 * loses context when the CPU enters the idle states. To solve
+	 * this issue the tick device must be linked to a power domain
+	 * so that the idle driver can check on which states the device
+	 * loses its context. Current code takes the conservative choice
+	 * of defining the idle state as one where the tick device always
+	 * loses its context. On platforms where tick device never loses
+	 * its context (ie it is not a C3STOP device) this turns into
+	 * a nop. On platforms where the tick device does lose context in some
+	 * states, this code can be optimized, when power domain specifications
+	 * for ARM CPUs are finalized.
+	 */
+	idle_state->flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TIMER_STOP;
+
+	strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN);
+	strncpy(idle_state->desc, state_node->name, CPUIDLE_NAME_LEN);
+
+	(*cnt)++;
+}
+
+static int __init init_idle_states(struct cpuidle_driver *drv,
+				   struct device_node *state_nodes[],
+				   unsigned int start_idx, bool init_nodes)
+{
+	struct state_elem *el;
+	struct list_head *curr, *tmp;
+	unsigned int cnt = start_idx;
+
+	list_for_each_entry(el, &head, list) {
+		/*
+		 * Check if the init function has to fill the
+		 * state_nodes array on behalf of the CPUidle driver.
+		 */
+		if (init_nodes)
+			state_nodes[cnt] = el->node;
+		/*
+		 * cnt is updated on return if a state was added.
+		 */
+		init_state_node(drv, el->node, &cnt);
+
+		if (cnt == CPUIDLE_STATE_MAX) {
+			pr_warn("State index reached static CPU idle state limit\n");
+			break;
+		}
+	}
+
+	drv->state_count = cnt;
+
+	list_for_each_safe(curr, tmp, &head) {
+		list_del(curr);
+		kfree(container_of(curr, struct state_elem, list));
+	}
+
+	/*
+	 * If no idle states are detected, return an error and let the idle
+	 * driver initialization fail accordingly.
+	 */
+	return (cnt > start_idx) ? 0 : -ENODATA;
+}
+
+static void __init add_idle_states(struct cpuidle_driver *drv,
+				   struct device_node *idle_states)
+{
+	struct device_node *state_node;
+
+	for_each_child_of_node(idle_states, state_node) {
+		if ((!of_device_is_compatible(state_node, "arm,idle-state"))) {
+			pr_warn(" * %s: children of /cpus/idle-states must be \"arm,idle-state\" compatible\n",
+				     state_node->full_name);
+			continue;
+		}
+		/*
+		 * If memory allocation fails, better bail out.
+		 * Initialized nodes are freed at initialization
+		 * completion in of_init_idle_driver().
+		 */
+		if ((add_state_node(drv->cpumask, state_node) == -ENOMEM))
+			break;
+	}
+	/*
+	 * Sort the states list before initializing the CPUidle driver
+	 * states array.
+	 */
+	list_sort(NULL, &head, state_cmp);
+}
+
+/*
+ * of_init_idle_driver - Parse the DT idle states and initialize the
+ *			 idle driver states array
+ *
+ * @drv:	  Pointer to CPU idle driver to be initialized
+ * @state_nodes:  Array of struct device_nodes to be initialized if
+ *		  init_nodes == true. Must be sized CPUIDLE_STATE_MAX
+ * @start_idx:    First idle state index to be initialized
+ * @init_nodes:   Boolean to request device nodes initialization
+ *
+ * Returns:
+ *	0 on success
+ *	<0 on failure
+ *
+ *	On success the states array in the cpuidle driver contains
+ *	initialized entries in the states array, starting from index start_idx.
+ *	If init_nodes == true, on success the state_nodes array is initialized
+ *	with idle state DT node pointers, starting from index start_idx,
+ *	in a 1:1 relation with the idle driver states array.
+ */
+int __init of_init_idle_driver(struct cpuidle_driver *drv,
+			       struct device_node *state_nodes[],
+			       unsigned int start_idx, bool init_nodes)
+{
+	struct device_node *idle_states_node;
+	int ret;
+
+	if (start_idx >= CPUIDLE_STATE_MAX) {
+		pr_warn("State index exceeds static CPU idle driver states array size\n");
+		return -EINVAL;
+	}
+
+	if (WARN(init_nodes && !state_nodes,
+		"Requested nodes stashing in an invalid nodes container\n"))
+		return -EINVAL;
+
+	idle_states_node = of_find_node_by_path("/cpus/idle-states");
+	if (!idle_states_node)
+		return -ENOENT;
+
+	add_idle_states(drv, idle_states_node);
+
+	ret = init_idle_states(drv, state_nodes, start_idx, init_nodes);
+
+	of_node_put(idle_states_node);
+
+	return ret;
+}
diff --git a/drivers/cpuidle/of_idle_states.h b/drivers/cpuidle/of_idle_states.h
new file mode 100644
index 0000000..049f94f
--- /dev/null
+++ b/drivers/cpuidle/of_idle_states.h
@@ -0,0 +1,8 @@
+#ifndef __OF_IDLE_STATES
+#define __OF_IDLE_STATES
+
+int __init of_init_idle_driver(struct cpuidle_driver *drv,
+			       struct device_node *state_nodes[],
+			       unsigned int start_idx,
+			       bool init_nodes);
+#endif
-- 
1.8.4

[PATCH RFC v2 1/4] drivers: cpuidle: implement OF based idle states infrastructure

[Lorenzo Pieralisi]

On most common ARM systems, the low-power states a CPU can be put into are
not discoverable in HW and require device tree bindings to describe
the respective power domains, power down protocol and idle states parameters.

In order to enable DT based idle states and configure idle drivers, this
patch implements the bulk infrastructure required to parse the device tree
idle states bindings and initialize the corresponding CPUidle driver states
data.

Code that initializes idle states checks the CPU idle driver cpumask so
that multiple CPU idle drivers can be initialized through it in the
kernel. The CPU idle driver cpumask defines which idle states should be
considered valid for the driver, ie idle states that are valid on a set
of cpus the idle driver manages.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
 drivers/cpuidle/Kconfig          |   9 ++
 drivers/cpuidle/Makefile         |   1 +
 drivers/cpuidle/of_idle_states.c | 274 +++++++++++++++++++++++++++++++++++++++
 drivers/cpuidle/of_idle_states.h |   8 ++
 4 files changed, 292 insertions(+)
 create mode 100644 drivers/cpuidle/of_idle_states.c
 create mode 100644 drivers/cpuidle/of_idle_states.h

diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index f04e25f..995654e 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -30,6 +30,15 @@ config CPU_IDLE_GOV_MENU
 	bool "Menu governor (for tickless system)"
 	default y
 
+config OF_IDLE_STATES
+        bool "Idle states DT support"
+	depends on ARM || ARM64
+	default n
+	help
+	 Allows the CPU idle framework to initialize CPU idle drivers
+	 state data by using DT provided nodes compliant with idle states
+	 device tree bindings.
+
 menu "ARM CPU Idle Drivers"
 depends on ARM
 source "drivers/cpuidle/Kconfig.arm"
diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index f71ae1b..2fc5139 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -4,6 +4,7 @@
 
 obj-y += cpuidle.o driver.o governor.o sysfs.o governors/
 obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
+obj-$(CONFIG_OF_IDLE_STATES)		  += of_idle_states.o
 
 ##################################################################################
 # ARM SoC drivers
diff --git a/drivers/cpuidle/of_idle_states.c b/drivers/cpuidle/of_idle_states.c
new file mode 100644
index 0000000..eceb1b4
--- /dev/null
+++ b/drivers/cpuidle/of_idle_states.c
@@ -0,0 +1,274 @@
+/*
+ * OF idle states parsing code.
+ *
+ * Copyright (C) 2014 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+ *
+ * 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/cpuidle.h>
+#include <linux/cpumask.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/list_sort.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+#include "of_idle_states.h"
+
+struct state_elem {
+	struct list_head list;
+	struct device_node *node;
+	int val;
+};
+
+static struct list_head head __initdata = LIST_HEAD_INIT(head);
+
+static bool __init state_cpu_valid(struct device_node *state_node,
+				   struct device_node *cpu_node)
+{
+	int i = 0;
+	struct device_node *cpu_state;
+
+	while ((cpu_state = of_parse_phandle(cpu_node,
+					     "cpu-idle-states", i++))) {
+		if (cpu_state && state_node == cpu_state) {
+			of_node_put(cpu_state);
+			return true;
+		}
+		of_node_put(cpu_state);
+	}
+	return false;
+}
+
+static bool __init state_cpus_valid(const cpumask_t *cpus,
+				    struct device_node *state_node)
+{
+	int cpu;
+	struct device_node *cpu_node;
+
+	/*
+	 * Check if state is valid on driver cpumask cpus
+	 */
+	for_each_cpu(cpu, cpus) {
+		cpu_node = of_get_cpu_node(cpu, NULL);
+
+		if (!cpu_node) {
+			pr_err("Missing device node for CPU %d\n", cpu);
+			return false;
+		}
+
+		if (!state_cpu_valid(state_node, cpu_node))
+			return false;
+	}
+
+	return true;
+}
+
+static int __init state_cmp(void *priv, struct list_head *a,
+			    struct list_head *b)
+{
+	struct state_elem *ela, *elb;
+
+	ela = container_of(a, struct state_elem, list);
+	elb = container_of(b, struct state_elem, list);
+
+	return ela->val - elb->val;
+}
+
+static int __init add_state_node(cpumask_t *cpumask,
+				 struct device_node *state_node)
+{
+	struct state_elem *el;
+	u32 val;
+
+	pr_debug(" * %s...\n", state_node->full_name);
+
+	if (!state_cpus_valid(cpumask, state_node))
+		return -EINVAL;
+	/*
+	 * Parse just the value required to sort the states.
+	 */
+	if (of_property_read_u32(state_node, "min-residency-us",
+				 &val)) {
+		pr_debug(" * %s missing min-residency-us property\n",
+			 state_node->full_name);
+		return -EINVAL;
+	}
+
+	el = kmalloc(sizeof(*el), GFP_KERNEL);
+	if (!el) {
+		pr_err("%s failed to allocate memory\n", __func__);
+		return -ENOMEM;
+	}
+
+	el->node = state_node;
+	el->val = val;
+	list_add_tail(&el->list, &head);
+
+	return 0;
+}
+
+static void __init init_state_node(struct cpuidle_driver *drv,
+				   struct device_node *state_node,
+				   int *cnt)
+{
+	struct cpuidle_state *idle_state;
+
+	pr_debug(" * %s...\n", state_node->full_name);
+
+	idle_state = &drv->states[*cnt];
+
+	if (of_property_read_u32(state_node, "exit-latency-us",
+				 &idle_state->exit_latency)) {
+		pr_debug(" * %s missing exit-latency-us property\n",
+			     state_node->full_name);
+		return;
+	}
+
+	if (of_property_read_u32(state_node, "min-residency-us",
+				 &idle_state->target_residency)) {
+		pr_debug(" * %s missing min-residency-us property\n",
+			     state_node->full_name);
+		return;
+	}
+	/*
+	 * It is unknown to the idle driver if and when the tick_device
+	 * loses context when the CPU enters the idle states. To solve
+	 * this issue the tick device must be linked to a power domain
+	 * so that the idle driver can check on which states the device
+	 * loses its context. Current code takes the conservative choice
+	 * of defining the idle state as one where the tick device always
+	 * loses its context. On platforms where tick device never loses
+	 * its context (ie it is not a C3STOP device) this turns into
+	 * a nop. On platforms where the tick device does lose context in some
+	 * states, this code can be optimized, when power domain specifications
+	 * for ARM CPUs are finalized.
+	 */
+	idle_state->flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TIMER_STOP;
+
+	strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN);
+	strncpy(idle_state->desc, state_node->name, CPUIDLE_NAME_LEN);
+
+	(*cnt)++;
+}
+
+static int __init init_idle_states(struct cpuidle_driver *drv,
+				   struct device_node *state_nodes[],
+				   unsigned int start_idx, bool init_nodes)
+{
+	struct state_elem *el;
+	struct list_head *curr, *tmp;
+	unsigned int cnt = start_idx;
+
+	list_for_each_entry(el, &head, list) {
+		/*
+		 * Check if the init function has to fill the
+		 * state_nodes array on behalf of the CPUidle driver.
+		 */
+		if (init_nodes)
+			state_nodes[cnt] = el->node;
+		/*
+		 * cnt is updated on return if a state was added.
+		 */
+		init_state_node(drv, el->node, &cnt);
+
+		if (cnt == CPUIDLE_STATE_MAX) {
+			pr_warn("State index reached static CPU idle state limit\n");
+			break;
+		}
+	}
+
+	drv->state_count = cnt;
+
+	list_for_each_safe(curr, tmp, &head) {
+		list_del(curr);
+		kfree(container_of(curr, struct state_elem, list));
+	}
+
+	/*
+	 * If no idle states are detected, return an error and let the idle
+	 * driver initialization fail accordingly.
+	 */
+	return (cnt > start_idx) ? 0 : -ENODATA;
+}
+
+static void __init add_idle_states(struct cpuidle_driver *drv,
+				   struct device_node *idle_states)
+{
+	struct device_node *state_node;
+
+	for_each_child_of_node(idle_states, state_node) {
+		if ((!of_device_is_compatible(state_node, "arm,idle-state"))) {
+			pr_warn(" * %s: children of /cpus/idle-states must be \"arm,idle-state\" compatible\n",
+				     state_node->full_name);
+			continue;
+		}
+		/*
+		 * If memory allocation fails, better bail out.
+		 * Initialized nodes are freed at initialization
+		 * completion in of_init_idle_driver().
+		 */
+		if ((add_state_node(drv->cpumask, state_node) == -ENOMEM))
+			break;
+	}
+	/*
+	 * Sort the states list before initializing the CPUidle driver
+	 * states array.
+	 */
+	list_sort(NULL, &head, state_cmp);
+}
+
+/*
+ * of_init_idle_driver - Parse the DT idle states and initialize the
+ *			 idle driver states array
+ *
+ * @drv:	  Pointer to CPU idle driver to be initialized
+ * @state_nodes:  Array of struct device_nodes to be initialized if
+ *		  init_nodes == true. Must be sized CPUIDLE_STATE_MAX
+ * @start_idx:    First idle state index to be initialized
+ * @init_nodes:   Boolean to request device nodes initialization
+ *
+ * Returns:
+ *	0 on success
+ *	<0 on failure
+ *
+ *	On success the states array in the cpuidle driver contains
+ *	initialized entries in the states array, starting from index start_idx.
+ *	If init_nodes == true, on success the state_nodes array is initialized
+ *	with idle state DT node pointers, starting from index start_idx,
+ *	in a 1:1 relation with the idle driver states array.
+ */
+int __init of_init_idle_driver(struct cpuidle_driver *drv,
+			       struct device_node *state_nodes[],
+			       unsigned int start_idx, bool init_nodes)
+{
+	struct device_node *idle_states_node;
+	int ret;
+
+	if (start_idx >= CPUIDLE_STATE_MAX) {
+		pr_warn("State index exceeds static CPU idle driver states array size\n");
+		return -EINVAL;
+	}
+
+	if (WARN(init_nodes && !state_nodes,
+		"Requested nodes stashing in an invalid nodes container\n"))
+		return -EINVAL;
+
+	idle_states_node = of_find_node_by_path("/cpus/idle-states");
+	if (!idle_states_node)
+		return -ENOENT;
+
+	add_idle_states(drv, idle_states_node);
+
+	ret = init_idle_states(drv, state_nodes, start_idx, init_nodes);
+
+	of_node_put(idle_states_node);
+
+	return ret;
+}
diff --git a/drivers/cpuidle/of_idle_states.h b/drivers/cpuidle/of_idle_states.h
new file mode 100644
index 0000000..049f94f
--- /dev/null
+++ b/drivers/cpuidle/of_idle_states.h
@@ -0,0 +1,8 @@
+#ifndef __OF_IDLE_STATES
+#define __OF_IDLE_STATES
+
+int __init of_init_idle_driver(struct cpuidle_driver *drv,
+			       struct device_node *state_nodes[],
+			       unsigned int start_idx,
+			       bool init_nodes);
+#endif
-- 
1.8.4

[PATCH RFC v2 2/4] arm64: add PSCI CPU_SUSPEND based cpu_suspend support

[Lorenzo Pieralisi]

This patch implements the cpu_suspend cpu operations method through
the PSCI CPU_SUSPEND API. The PSCI implementation translates the idle state
index passed by the cpu_suspend core call into a valid PSCI state according to
the PSCI states initialized at boot by the PSCI suspend backend.

Entry point is set to cpu_resume physical address, that represents the
default kernel execution address following a CPU reset.

Idle state indices missing a DT node description are initialized to power
state standby WFI so that if called by the idle driver they provide the
default behaviour.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
 arch/arm64/include/asm/psci.h |   4 ++
 arch/arm64/kernel/psci.c      | 102 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 106 insertions(+)

diff --git a/arch/arm64/include/asm/psci.h b/arch/arm64/include/asm/psci.h
index d15ab8b4..9a4b663 100644
--- a/arch/arm64/include/asm/psci.h
+++ b/arch/arm64/include/asm/psci.h
@@ -14,6 +14,10 @@
 #ifndef __ASM_PSCI_H
 #define __ASM_PSCI_H
 
+struct cpuidle_driver;
 void psci_init(void);
 
+int __init psci_dt_register_idle_states(struct cpuidle_driver *,
+					struct device_node *[]);
+
 #endif /* __ASM_PSCI_H */
diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index ea4828a..0e32ab4 100644
--- a/arch/arm64/kernel/psci.c
+++ b/arch/arm64/kernel/psci.c
@@ -15,15 +15,18 @@
 
 #define pr_fmt(fmt) "psci: " fmt
 
+#include <linux/cpuidle.h>
 #include <linux/init.h>
 #include <linux/of.h>
 #include <linux/smp.h>
+#include <linux/slab.h>
 
 #include <asm/compiler.h>
 #include <asm/cpu_ops.h>
 #include <asm/errno.h>
 #include <asm/psci.h>
 #include <asm/smp_plat.h>
+#include <asm/suspend.h>
 
 #define PSCI_POWER_STATE_TYPE_STANDBY		0
 #define PSCI_POWER_STATE_TYPE_POWER_DOWN	1
@@ -54,6 +57,8 @@ enum psci_function {
 	PSCI_FN_MAX,
 };
 
+static DEFINE_PER_CPU_READ_MOSTLY(struct psci_power_state *, psci_power_state);
+
 static u32 psci_function_id[PSCI_FN_MAX];
 
 #define PSCI_RET_SUCCESS		0
@@ -94,6 +99,17 @@ static u32 psci_power_state_pack(struct psci_power_state state)
 			<< PSCI_POWER_STATE_AFFL_SHIFT);
 }
 
+static void psci_power_state_unpack(u32 power_state,
+				    struct psci_power_state *state)
+{
+	state->id = (power_state >> PSCI_POWER_STATE_ID_SHIFT)
+			& PSCI_POWER_STATE_ID_MASK;
+	state->type = (power_state >> PSCI_POWER_STATE_TYPE_SHIFT)
+			& PSCI_POWER_STATE_TYPE_MASK;
+	state->affinity_level = (power_state >> PSCI_POWER_STATE_AFFL_SHIFT)
+			& PSCI_POWER_STATE_AFFL_MASK;
+}
+
 /*
  * The following two functions are invoked via the invoke_psci_fn pointer
  * and will not be inlined, allowing us to piggyback on the AAPCS.
@@ -176,6 +192,77 @@ static const struct of_device_id psci_of_match[] __initconst = {
 	{},
 };
 
+int __init psci_dt_register_idle_states(struct cpuidle_driver *drv,
+					struct device_node *state_nodes[])
+{
+	int cpu, i;
+	struct psci_power_state *psci_states;
+	const struct cpu_operations *cpu_ops_ptr;
+
+	if (!state_nodes)
+		return -EINVAL;
+	/*
+	 * This is belt-and-braces: make sure that if the idle
+	 * specified protocol is psci, the cpu_ops have been
+	 * initialized to psci operations. Anything else is
+	 * a recipe for mayhem.
+	 */
+	for_each_cpu(cpu, drv->cpumask) {
+		cpu_ops_ptr = cpu_ops[cpu];
+		if (WARN_ON(!cpu_ops_ptr || strcmp(cpu_ops_ptr->name, "psci")))
+			return -EOPNOTSUPP;
+	}
+
+	psci_states = kcalloc(drv->state_count, sizeof(*psci_states),
+			      GFP_KERNEL);
+
+	if (!psci_states) {
+		pr_warn("psci idle state allocation failed\n");
+		return -ENOMEM;
+	}
+
+	for_each_cpu(cpu, drv->cpumask) {
+		if (per_cpu(psci_power_state, cpu)) {
+			pr_warn("idle states already initialized on cpu %u\n",
+				cpu);
+			continue;
+		}
+		per_cpu(psci_power_state, cpu) = psci_states;
+	}
+
+
+	for (i = 0; i < drv->state_count; i++) {
+		u32 psci_power_state;
+
+		if (!state_nodes[i]) {
+			/*
+			 * An index with a missing node pointer falls back to
+			 * simple STANDBYWFI
+			 */
+			psci_states[i].type = PSCI_POWER_STATE_TYPE_STANDBY;
+			continue;
+		}
+
+		if (of_property_read_u32(state_nodes[i], "entry-method-param",
+					 &psci_power_state)) {
+			pr_warn(" * %s missing entry-method-param property\n",
+				state_nodes[i]->full_name);
+			/*
+			 * If entry-method-param property is missing, fall
+			 * back to STANDBYWFI state
+			 */
+			psci_states[i].type = PSCI_POWER_STATE_TYPE_STANDBY;
+			continue;
+		}
+
+		pr_debug("psci-power-state %#x index %u\n",
+			 psci_power_state, i);
+		psci_power_state_unpack(psci_power_state, &psci_states[i]);
+	}
+
+	return 0;
+}
+
 void __init psci_init(void)
 {
 	struct device_node *np;
@@ -279,6 +366,18 @@ static void cpu_psci_cpu_die(unsigned int cpu)
 }
 #endif
 
+#ifdef CONFIG_ARM64_CPU_SUSPEND
+static int cpu_psci_cpu_suspend(unsigned long index)
+{
+	struct psci_power_state *state = __get_cpu_var(psci_power_state);
+
+	if (!state)
+		return -EOPNOTSUPP;
+
+	return psci_ops.cpu_suspend(state[index], virt_to_phys(cpu_resume));
+}
+#endif
+
 const struct cpu_operations cpu_psci_ops = {
 	.name		= "psci",
 	.cpu_init	= cpu_psci_cpu_init,
@@ -288,6 +387,9 @@ const struct cpu_operations cpu_psci_ops = {
 	.cpu_disable	= cpu_psci_cpu_disable,
 	.cpu_die	= cpu_psci_cpu_die,
 #endif
+#ifdef CONFIG_ARM64_CPU_SUSPEND
+	.cpu_suspend	= cpu_psci_cpu_suspend,
+#endif
 };
 
 #endif
-- 
1.8.4

[PATCH RFC v2 2/4] arm64: add PSCI CPU_SUSPEND based cpu_suspend support

[Lorenzo Pieralisi]

This patch implements the cpu_suspend cpu operations method through
the PSCI CPU_SUSPEND API. The PSCI implementation translates the idle state
index passed by the cpu_suspend core call into a valid PSCI state according to
the PSCI states initialized at boot by the PSCI suspend backend.

Entry point is set to cpu_resume physical address, that represents the
default kernel execution address following a CPU reset.

Idle state indices missing a DT node description are initialized to power
state standby WFI so that if called by the idle driver they provide the
default behaviour.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
 arch/arm64/include/asm/psci.h |   4 ++
 arch/arm64/kernel/psci.c      | 102 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 106 insertions(+)

diff --git a/arch/arm64/include/asm/psci.h b/arch/arm64/include/asm/psci.h
index d15ab8b4..9a4b663 100644
--- a/arch/arm64/include/asm/psci.h
+++ b/arch/arm64/include/asm/psci.h
@@ -14,6 +14,10 @@
 #ifndef __ASM_PSCI_H
 #define __ASM_PSCI_H
 
+struct cpuidle_driver;
 void psci_init(void);
 
+int __init psci_dt_register_idle_states(struct cpuidle_driver *,
+					struct device_node *[]);
+
 #endif /* __ASM_PSCI_H */
diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index ea4828a..0e32ab4 100644
--- a/arch/arm64/kernel/psci.c
+++ b/arch/arm64/kernel/psci.c
@@ -15,15 +15,18 @@
 
 #define pr_fmt(fmt) "psci: " fmt
 
+#include <linux/cpuidle.h>
 #include <linux/init.h>
 #include <linux/of.h>
 #include <linux/smp.h>
+#include <linux/slab.h>
 
 #include <asm/compiler.h>
 #include <asm/cpu_ops.h>
 #include <asm/errno.h>
 #include <asm/psci.h>
 #include <asm/smp_plat.h>
+#include <asm/suspend.h>
 
 #define PSCI_POWER_STATE_TYPE_STANDBY		0
 #define PSCI_POWER_STATE_TYPE_POWER_DOWN	1
@@ -54,6 +57,8 @@ enum psci_function {
 	PSCI_FN_MAX,
 };
 
+static DEFINE_PER_CPU_READ_MOSTLY(struct psci_power_state *, psci_power_state);
+
 static u32 psci_function_id[PSCI_FN_MAX];
 
 #define PSCI_RET_SUCCESS		0
@@ -94,6 +99,17 @@ static u32 psci_power_state_pack(struct psci_power_state state)
 			<< PSCI_POWER_STATE_AFFL_SHIFT);
 }
 
+static void psci_power_state_unpack(u32 power_state,
+				    struct psci_power_state *state)
+{
+	state->id = (power_state >> PSCI_POWER_STATE_ID_SHIFT)
+			& PSCI_POWER_STATE_ID_MASK;
+	state->type = (power_state >> PSCI_POWER_STATE_TYPE_SHIFT)
+			& PSCI_POWER_STATE_TYPE_MASK;
+	state->affinity_level = (power_state >> PSCI_POWER_STATE_AFFL_SHIFT)
+			& PSCI_POWER_STATE_AFFL_MASK;
+}
+
 /*
  * The following two functions are invoked via the invoke_psci_fn pointer
  * and will not be inlined, allowing us to piggyback on the AAPCS.
@@ -176,6 +192,77 @@ static const struct of_device_id psci_of_match[] __initconst = {
 	{},
 };
 
+int __init psci_dt_register_idle_states(struct cpuidle_driver *drv,
+					struct device_node *state_nodes[])
+{
+	int cpu, i;
+	struct psci_power_state *psci_states;
+	const struct cpu_operations *cpu_ops_ptr;
+
+	if (!state_nodes)
+		return -EINVAL;
+	/*
+	 * This is belt-and-braces: make sure that if the idle
+	 * specified protocol is psci, the cpu_ops have been
+	 * initialized to psci operations. Anything else is
+	 * a recipe for mayhem.
+	 */
+	for_each_cpu(cpu, drv->cpumask) {
+		cpu_ops_ptr = cpu_ops[cpu];
+		if (WARN_ON(!cpu_ops_ptr || strcmp(cpu_ops_ptr->name, "psci")))
+			return -EOPNOTSUPP;
+	}
+
+	psci_states = kcalloc(drv->state_count, sizeof(*psci_states),
+			      GFP_KERNEL);
+
+	if (!psci_states) {
+		pr_warn("psci idle state allocation failed\n");
+		return -ENOMEM;
+	}
+
+	for_each_cpu(cpu, drv->cpumask) {
+		if (per_cpu(psci_power_state, cpu)) {
+			pr_warn("idle states already initialized on cpu %u\n",
+				cpu);
+			continue;
+		}
+		per_cpu(psci_power_state, cpu) = psci_states;
+	}
+
+
+	for (i = 0; i < drv->state_count; i++) {
+		u32 psci_power_state;
+
+		if (!state_nodes[i]) {
+			/*
+			 * An index with a missing node pointer falls back to
+			 * simple STANDBYWFI
+			 */
+			psci_states[i].type = PSCI_POWER_STATE_TYPE_STANDBY;
+			continue;
+		}
+
+		if (of_property_read_u32(state_nodes[i], "entry-method-param",
+					 &psci_power_state)) {
+			pr_warn(" * %s missing entry-method-param property\n",
+				state_nodes[i]->full_name);
+			/*
+			 * If entry-method-param property is missing, fall
+			 * back to STANDBYWFI state
+			 */
+			psci_states[i].type = PSCI_POWER_STATE_TYPE_STANDBY;
+			continue;
+		}
+
+		pr_debug("psci-power-state %#x index %u\n",
+			 psci_power_state, i);
+		psci_power_state_unpack(psci_power_state, &psci_states[i]);
+	}
+
+	return 0;
+}
+
 void __init psci_init(void)
 {
 	struct device_node *np;
@@ -279,6 +366,18 @@ static void cpu_psci_cpu_die(unsigned int cpu)
 }
 #endif
 
+#ifdef CONFIG_ARM64_CPU_SUSPEND
+static int cpu_psci_cpu_suspend(unsigned long index)
+{
+	struct psci_power_state *state = __get_cpu_var(psci_power_state);
+
+	if (!state)
+		return -EOPNOTSUPP;
+
+	return psci_ops.cpu_suspend(state[index], virt_to_phys(cpu_resume));
+}
+#endif
+
 const struct cpu_operations cpu_psci_ops = {
 	.name		= "psci",
 	.cpu_init	= cpu_psci_cpu_init,
@@ -288,6 +387,9 @@ const struct cpu_operations cpu_psci_ops = {
 	.cpu_disable	= cpu_psci_cpu_disable,
 	.cpu_die	= cpu_psci_cpu_die,
 #endif
+#ifdef CONFIG_ARM64_CPU_SUSPEND
+	.cpu_suspend	= cpu_psci_cpu_suspend,
+#endif
 };
 
 #endif
-- 
1.8.4

[PATCH RFC v2 3/4] drivers: cpuidle: CPU idle ARM64 driver

[Lorenzo Pieralisi]

This patch implements a generic CPU idle driver for ARM64 machines.

It relies on the DT idle states infrastructure to initialize idle
states count and respective parameters. Current code assumes the driver
is managing idle states on all possible CPUs but can be easily
generalized to support heterogenous systems and build cpumasks at
runtime using MIDRs or DT cpu nodes compatible properties.

Suspend back-ends (eg PSCI) must register a suspend initializer with
the CPU idle driver so that the suspend backend call can be detected,
and the driver code can call the back-end infrastructure to complete the
suspend backend initialization.

Idle state index 0 is always initialized as a simple wfi state, ie always
considered present and functional on all ARM64 platforms.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi-5wv7dgnIgG8@public.gmane.org>
---
 drivers/cpuidle/Kconfig         |   5 ++
 drivers/cpuidle/Kconfig.arm64   |  13 ++++
 drivers/cpuidle/Makefile        |   4 +
 drivers/cpuidle/cpuidle-arm64.c | 159 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 181 insertions(+)
 create mode 100644 drivers/cpuidle/Kconfig.arm64
 create mode 100644 drivers/cpuidle/cpuidle-arm64.c

diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index 995654e..0654eb5 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -44,6 +44,11 @@ depends on ARM
 source "drivers/cpuidle/Kconfig.arm"
 endmenu
 
+menu "ARM64 CPU Idle Drivers"
+depends on ARM64
+source "drivers/cpuidle/Kconfig.arm64"
+endmenu
+
 menu "POWERPC CPU Idle Drivers"
 depends on PPC
 source "drivers/cpuidle/Kconfig.powerpc"
diff --git a/drivers/cpuidle/Kconfig.arm64 b/drivers/cpuidle/Kconfig.arm64
new file mode 100644
index 0000000..b83612c
--- /dev/null
+++ b/drivers/cpuidle/Kconfig.arm64
@@ -0,0 +1,13 @@
+#
+# ARM64 CPU Idle drivers
+#
+
+config ARM64_CPUIDLE
+	bool "Generic ARM64 CPU idle Driver"
+	select OF_IDLE_STATES
+	help
+	  Select this to enable generic cpuidle driver for ARM v8.
+	  It provides a generic idle driver whose idle states are configured
+	  at run-time through DT nodes. The CPUidle suspend backend is
+	  initialized by the device tree parsing code on matching the entry
+	  method to the respective CPU operations.
diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index 2fc5139..161a5f2 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -16,6 +16,10 @@ obj-$(CONFIG_ARM_U8500_CPUIDLE)         += cpuidle-ux500.o
 obj-$(CONFIG_ARM_AT91_CPUIDLE)          += cpuidle-at91.o
 
 ###############################################################################
+# ARM64 drivers
+obj-$(CONFIG_ARM64_CPUIDLE)		+= cpuidle-arm64.o
+
+###############################################################################
 # POWERPC drivers
 obj-$(CONFIG_PSERIES_CPUIDLE)		+= cpuidle-pseries.o
 obj-$(CONFIG_POWERNV_CPUIDLE)		+= cpuidle-powernv.o
diff --git a/drivers/cpuidle/cpuidle-arm64.c b/drivers/cpuidle/cpuidle-arm64.c
new file mode 100644
index 0000000..2cfde6c
--- /dev/null
+++ b/drivers/cpuidle/cpuidle-arm64.c
@@ -0,0 +1,159 @@
+/*
+ * ARM64 generic CPU idle driver.
+ *
+ * Copyright (C) 2014 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi-5wv7dgnIgG8@public.gmane.org>
+ *
+ * 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/cpuidle.h>
+#include <linux/cpumask.h>
+#include <linux/cpu_pm.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+
+#include <asm/psci.h>
+#include <asm/suspend.h>
+
+#include "of_idle_states.h"
+
+typedef int (*suspend_init_fn)(struct cpuidle_driver *,
+			       struct device_node *[]);
+
+struct cpu_suspend_ops {
+	const char *id;
+	suspend_init_fn init_fn;
+};
+
+static const struct cpu_suspend_ops suspend_operations[] __initconst = {
+	{"arm,psci", psci_dt_register_idle_states},
+	{}
+};
+
+static __init const struct cpu_suspend_ops *get_suspend_ops(const char *str)
+{
+	int i;
+
+	if (!str)
+		return NULL;
+
+	for (i = 0; suspend_operations[i].id; i++)
+		if (!strcmp(suspend_operations[i].id, str))
+			return &suspend_operations[i];
+
+	return NULL;
+}
+
+/*
+ * arm_enter_idle_state - Programs CPU to enter the specified state
+ *
+ * @dev: cpuidle device
+ * @drv: cpuidle driver
+ * @idx: state index
+ *
+ * Called from the CPUidle framework to program the device to the
+ * specified target state selected by the governor.
+ */
+static int arm_enter_idle_state(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv, int idx)
+{
+	int ret;
+
+	if (!idx) {
+		cpu_do_idle();
+		return idx;
+	}
+
+	cpu_pm_enter();
+	/*
+	 * Pass idle state index to cpu_suspend which in turn will call
+	 * the CPU ops suspend protocol with idle index as a parameter.
+	 *
+	 * Some states would not require context to be saved and flushed
+	 * to DRAM, so calling cpu_suspend would not be stricly necessary.
+	 * When power domains specifications for ARM CPUs are finalized then
+	 * this code can be optimized to prevent saving registers if not
+	 * needed.
+	 */
+	ret = cpu_suspend(idx);
+
+	cpu_pm_exit();
+
+	return ret ? -1 : idx;
+}
+
+struct cpuidle_driver arm64_idle_driver = {
+	.name = "arm64_idle",
+	.owner = THIS_MODULE,
+};
+
+static struct device_node *state_nodes[CPUIDLE_STATE_MAX] __initdata;
+
+/*
+ * arm64_idle_init
+ *
+ * Registers the arm64 specific cpuidle driver with the cpuidle
+ * framework. It relies on core code to parse the idle states
+ * and initialize them using driver data structures accordingly.
+ */
+static int __init arm64_idle_init(void)
+{
+	int i, ret;
+	const char *entry_method;
+	struct device_node *idle_states_node;
+	const struct cpu_suspend_ops *suspend_init;
+	struct cpuidle_driver *drv = &arm64_idle_driver;
+
+	idle_states_node = of_find_node_by_path("/cpus/idle-states");
+	if (!idle_states_node)
+		return -ENOENT;
+
+	if (of_property_read_string(idle_states_node, "entry-method",
+				    &entry_method)) {
+		pr_warn(" * %s missing entry-method property\n",
+			    idle_states_node->full_name);
+		of_node_put(idle_states_node);
+		return -EOPNOTSUPP;
+	}
+
+	suspend_init = get_suspend_ops(entry_method);
+	if (!suspend_init) {
+		pr_warn("Missing suspend initializer\n");
+		of_node_put(idle_states_node);
+		return -EOPNOTSUPP;
+	}
+
+	/*
+	 * State at index 0 is standby wfi and considered standard
+	 * on all ARM platforms. If in some platforms simple wfi
+	 * can't be used as "state 0", DT bindings must be implemented
+	 * to work around this issue and allow installing a special
+	 * handler for idle state index 0.
+	 */
+	drv->states[0].exit_latency = 1;
+	drv->states[0].target_residency = 1;
+	drv->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
+	strncpy(drv->states[0].name, "ARM WFI", CPUIDLE_NAME_LEN);
+	strncpy(drv->states[0].desc, "ARM WFI", CPUIDLE_DESC_LEN);
+
+	drv->cpumask = (struct cpumask *) cpu_possible_mask;
+	/*
+	 * Start at index 1, request idle state nodes to be filled
+	 */
+	ret = of_init_idle_driver(drv, state_nodes, 1, true);
+	if (ret)
+		return ret;
+
+	if (suspend_init->init_fn(drv, state_nodes))
+		return -EOPNOTSUPP;
+
+	for (i = 0; i < drv->state_count; i++)
+		drv->states[i].enter = arm_enter_idle_state;
+
+	return cpuidle_register(drv, NULL);
+}
+device_initcall(arm64_idle_init);
-- 
1.8.4


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[PATCH RFC v2 3/4] drivers: cpuidle: CPU idle ARM64 driver

[Lorenzo Pieralisi]

This patch implements a generic CPU idle driver for ARM64 machines.

It relies on the DT idle states infrastructure to initialize idle
states count and respective parameters. Current code assumes the driver
is managing idle states on all possible CPUs but can be easily
generalized to support heterogenous systems and build cpumasks at
runtime using MIDRs or DT cpu nodes compatible properties.

Suspend back-ends (eg PSCI) must register a suspend initializer with
the CPU idle driver so that the suspend backend call can be detected,
and the driver code can call the back-end infrastructure to complete the
suspend backend initialization.

Idle state index 0 is always initialized as a simple wfi state, ie always
considered present and functional on all ARM64 platforms.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
 drivers/cpuidle/Kconfig         |   5 ++
 drivers/cpuidle/Kconfig.arm64   |  13 ++++
 drivers/cpuidle/Makefile        |   4 +
 drivers/cpuidle/cpuidle-arm64.c | 159 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 181 insertions(+)
 create mode 100644 drivers/cpuidle/Kconfig.arm64
 create mode 100644 drivers/cpuidle/cpuidle-arm64.c

diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index 995654e..0654eb5 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -44,6 +44,11 @@ depends on ARM
 source "drivers/cpuidle/Kconfig.arm"
 endmenu
 
+menu "ARM64 CPU Idle Drivers"
+depends on ARM64
+source "drivers/cpuidle/Kconfig.arm64"
+endmenu
+
 menu "POWERPC CPU Idle Drivers"
 depends on PPC
 source "drivers/cpuidle/Kconfig.powerpc"
diff --git a/drivers/cpuidle/Kconfig.arm64 b/drivers/cpuidle/Kconfig.arm64
new file mode 100644
index 0000000..b83612c
--- /dev/null
+++ b/drivers/cpuidle/Kconfig.arm64
@@ -0,0 +1,13 @@
+#
+# ARM64 CPU Idle drivers
+#
+
+config ARM64_CPUIDLE
+	bool "Generic ARM64 CPU idle Driver"
+	select OF_IDLE_STATES
+	help
+	  Select this to enable generic cpuidle driver for ARM v8.
+	  It provides a generic idle driver whose idle states are configured
+	  at run-time through DT nodes. The CPUidle suspend backend is
+	  initialized by the device tree parsing code on matching the entry
+	  method to the respective CPU operations.
diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index 2fc5139..161a5f2 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -16,6 +16,10 @@ obj-$(CONFIG_ARM_U8500_CPUIDLE)         += cpuidle-ux500.o
 obj-$(CONFIG_ARM_AT91_CPUIDLE)          += cpuidle-at91.o
 
 ###############################################################################
+# ARM64 drivers
+obj-$(CONFIG_ARM64_CPUIDLE)		+= cpuidle-arm64.o
+
+###############################################################################
 # POWERPC drivers
 obj-$(CONFIG_PSERIES_CPUIDLE)		+= cpuidle-pseries.o
 obj-$(CONFIG_POWERNV_CPUIDLE)		+= cpuidle-powernv.o
diff --git a/drivers/cpuidle/cpuidle-arm64.c b/drivers/cpuidle/cpuidle-arm64.c
new file mode 100644
index 0000000..2cfde6c
--- /dev/null
+++ b/drivers/cpuidle/cpuidle-arm64.c
@@ -0,0 +1,159 @@
+/*
+ * ARM64 generic CPU idle driver.
+ *
+ * Copyright (C) 2014 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+ *
+ * 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/cpuidle.h>
+#include <linux/cpumask.h>
+#include <linux/cpu_pm.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+
+#include <asm/psci.h>
+#include <asm/suspend.h>
+
+#include "of_idle_states.h"
+
+typedef int (*suspend_init_fn)(struct cpuidle_driver *,
+			       struct device_node *[]);
+
+struct cpu_suspend_ops {
+	const char *id;
+	suspend_init_fn init_fn;
+};
+
+static const struct cpu_suspend_ops suspend_operations[] __initconst = {
+	{"arm,psci", psci_dt_register_idle_states},
+	{}
+};
+
+static __init const struct cpu_suspend_ops *get_suspend_ops(const char *str)
+{
+	int i;
+
+	if (!str)
+		return NULL;
+
+	for (i = 0; suspend_operations[i].id; i++)
+		if (!strcmp(suspend_operations[i].id, str))
+			return &suspend_operations[i];
+
+	return NULL;
+}
+
+/*
+ * arm_enter_idle_state - Programs CPU to enter the specified state
+ *
+ * @dev: cpuidle device
+ * @drv: cpuidle driver
+ * @idx: state index
+ *
+ * Called from the CPUidle framework to program the device to the
+ * specified target state selected by the governor.
+ */
+static int arm_enter_idle_state(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv, int idx)
+{
+	int ret;
+
+	if (!idx) {
+		cpu_do_idle();
+		return idx;
+	}
+
+	cpu_pm_enter();
+	/*
+	 * Pass idle state index to cpu_suspend which in turn will call
+	 * the CPU ops suspend protocol with idle index as a parameter.
+	 *
+	 * Some states would not require context to be saved and flushed
+	 * to DRAM, so calling cpu_suspend would not be stricly necessary.
+	 * When power domains specifications for ARM CPUs are finalized then
+	 * this code can be optimized to prevent saving registers if not
+	 * needed.
+	 */
+	ret = cpu_suspend(idx);
+
+	cpu_pm_exit();
+
+	return ret ? -1 : idx;
+}
+
+struct cpuidle_driver arm64_idle_driver = {
+	.name = "arm64_idle",
+	.owner = THIS_MODULE,
+};
+
+static struct device_node *state_nodes[CPUIDLE_STATE_MAX] __initdata;
+
+/*
+ * arm64_idle_init
+ *
+ * Registers the arm64 specific cpuidle driver with the cpuidle
+ * framework. It relies on core code to parse the idle states
+ * and initialize them using driver data structures accordingly.
+ */
+static int __init arm64_idle_init(void)
+{
+	int i, ret;
+	const char *entry_method;
+	struct device_node *idle_states_node;
+	const struct cpu_suspend_ops *suspend_init;
+	struct cpuidle_driver *drv = &arm64_idle_driver;
+
+	idle_states_node = of_find_node_by_path("/cpus/idle-states");
+	if (!idle_states_node)
+		return -ENOENT;
+
+	if (of_property_read_string(idle_states_node, "entry-method",
+				    &entry_method)) {
+		pr_warn(" * %s missing entry-method property\n",
+			    idle_states_node->full_name);
+		of_node_put(idle_states_node);
+		return -EOPNOTSUPP;
+	}
+
+	suspend_init = get_suspend_ops(entry_method);
+	if (!suspend_init) {
+		pr_warn("Missing suspend initializer\n");
+		of_node_put(idle_states_node);
+		return -EOPNOTSUPP;
+	}
+
+	/*
+	 * State at index 0 is standby wfi and considered standard
+	 * on all ARM platforms. If in some platforms simple wfi
+	 * can't be used as "state 0", DT bindings must be implemented
+	 * to work around this issue and allow installing a special
+	 * handler for idle state index 0.
+	 */
+	drv->states[0].exit_latency = 1;
+	drv->states[0].target_residency = 1;
+	drv->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
+	strncpy(drv->states[0].name, "ARM WFI", CPUIDLE_NAME_LEN);
+	strncpy(drv->states[0].desc, "ARM WFI", CPUIDLE_DESC_LEN);
+
+	drv->cpumask = (struct cpumask *) cpu_possible_mask;
+	/*
+	 * Start at index 1, request idle state nodes to be filled
+	 */
+	ret = of_init_idle_driver(drv, state_nodes, 1, true);
+	if (ret)
+		return ret;
+
+	if (suspend_init->init_fn(drv, state_nodes))
+		return -EOPNOTSUPP;
+
+	for (i = 0; i < drv->state_count; i++)
+		drv->states[i].enter = arm_enter_idle_state;
+
+	return cpuidle_register(drv, NULL);
+}
+device_initcall(arm64_idle_init);
-- 
1.8.4

[PATCH RFC v2 4/4] arm64: boot: dts: update rtsm aemv8 dts with PSCI and idle states

[Lorenzo Pieralisi]

This patch updates the RTSM dts file with PSCI bindings and nodes
describing the AEMv8 model idle states parameters.

PSCI function IDs compliancy with PSCI v0.2 is still under development
so this patch provides PSCI function IDs for demonstration purposes only.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
 arch/arm64/boot/dts/rtsm_ve-aemv8a.dts | 49 ++++++++++++++++++++++++++++------
 1 file changed, 41 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/boot/dts/rtsm_ve-aemv8a.dts b/arch/arm64/boot/dts/rtsm_ve-aemv8a.dts
index d79de9c..fd23737 100644
--- a/arch/arm64/boot/dts/rtsm_ve-aemv8a.dts
+++ b/arch/arm64/boot/dts/rtsm_ve-aemv8a.dts
@@ -27,37 +27,70 @@
 		serial3 = &v2m_serial3;
 	};
 
+	psci {
+		compatible = "arm,psci";
+		method = "smc";
+		/*
+		 * Function IDs usage and compliancy with PSCI v0.2 still
+		 * under discussion.  Current IDs should be considered
+		 * temporary for demonstration purposes.
+		 */
+		cpu_suspend = <0x84000001>;
+		cpu_off = <0x84000002>;
+		cpu_on = <0x84000003>;
+	};
+
 	cpus {
 		#address-cells = <2>;
 		#size-cells = <0>;
 
+		idle-states {
+			entry-method = "arm,psci";
+
+			CPU_SLEEP_0: cpu-sleep-0 {
+				compatible = "arm,idle-state";
+				entry-method-param = <0x0010000>;
+				entry-latency-us = <40>;
+				exit-latency-us = <100>;
+				min-residency-us = <150>;
+			};
+
+			CLUSTER_SLEEP_0: cluster-sleep-0 {
+				compatible = "arm,idle-state";
+				entry-method-param = <0x1010000>;
+				entry-latency-us = <500>;
+				exit-latency-us = <1000>;
+				min-residency-us = <2500>;
+			};
+		};
+
 		cpu@0 {
 			device_type = "cpu";
 			compatible = "arm,armv8";
 			reg = <0x0 0x0>;
-			enable-method = "spin-table";
-			cpu-release-addr = <0x0 0x8000fff8>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
 		};
 		cpu@1 {
 			device_type = "cpu";
 			compatible = "arm,armv8";
 			reg = <0x0 0x1>;
-			enable-method = "spin-table";
-			cpu-release-addr = <0x0 0x8000fff8>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
 		};
 		cpu@2 {
 			device_type = "cpu";
 			compatible = "arm,armv8";
 			reg = <0x0 0x2>;
-			enable-method = "spin-table";
-			cpu-release-addr = <0x0 0x8000fff8>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
 		};
 		cpu@3 {
 			device_type = "cpu";
 			compatible = "arm,armv8";
 			reg = <0x0 0x3>;
-			enable-method = "spin-table";
-			cpu-release-addr = <0x0 0x8000fff8>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
 		};
 	};
 
-- 
1.8.4

[PATCH RFC v2 4/4] arm64: boot: dts: update rtsm aemv8 dts with PSCI and idle states

[Lorenzo Pieralisi]

This patch updates the RTSM dts file with PSCI bindings and nodes
describing the AEMv8 model idle states parameters.

PSCI function IDs compliancy with PSCI v0.2 is still under development
so this patch provides PSCI function IDs for demonstration purposes only.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
 arch/arm64/boot/dts/rtsm_ve-aemv8a.dts | 49 ++++++++++++++++++++++++++++------
 1 file changed, 41 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/boot/dts/rtsm_ve-aemv8a.dts b/arch/arm64/boot/dts/rtsm_ve-aemv8a.dts
index d79de9c..fd23737 100644
--- a/arch/arm64/boot/dts/rtsm_ve-aemv8a.dts
+++ b/arch/arm64/boot/dts/rtsm_ve-aemv8a.dts
@@ -27,37 +27,70 @@
 		serial3 = &v2m_serial3;
 	};
 
+	psci {
+		compatible = "arm,psci";
+		method = "smc";
+		/*
+		 * Function IDs usage and compliancy with PSCI v0.2 still
+		 * under discussion.  Current IDs should be considered
+		 * temporary for demonstration purposes.
+		 */
+		cpu_suspend = <0x84000001>;
+		cpu_off = <0x84000002>;
+		cpu_on = <0x84000003>;
+	};
+
 	cpus {
 		#address-cells = <2>;
 		#size-cells = <0>;
 
+		idle-states {
+			entry-method = "arm,psci";
+
+			CPU_SLEEP_0: cpu-sleep-0 {
+				compatible = "arm,idle-state";
+				entry-method-param = <0x0010000>;
+				entry-latency-us = <40>;
+				exit-latency-us = <100>;
+				min-residency-us = <150>;
+			};
+
+			CLUSTER_SLEEP_0: cluster-sleep-0 {
+				compatible = "arm,idle-state";
+				entry-method-param = <0x1010000>;
+				entry-latency-us = <500>;
+				exit-latency-us = <1000>;
+				min-residency-us = <2500>;
+			};
+		};
+
 		cpu at 0 {
 			device_type = "cpu";
 			compatible = "arm,armv8";
 			reg = <0x0 0x0>;
-			enable-method = "spin-table";
-			cpu-release-addr = <0x0 0x8000fff8>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
 		};
 		cpu at 1 {
 			device_type = "cpu";
 			compatible = "arm,armv8";
 			reg = <0x0 0x1>;
-			enable-method = "spin-table";
-			cpu-release-addr = <0x0 0x8000fff8>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
 		};
 		cpu at 2 {
 			device_type = "cpu";
 			compatible = "arm,armv8";
 			reg = <0x0 0x2>;
-			enable-method = "spin-table";
-			cpu-release-addr = <0x0 0x8000fff8>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
 		};
 		cpu at 3 {
 			device_type = "cpu";
 			compatible = "arm,armv8";
 			reg = <0x0 0x3>;
-			enable-method = "spin-table";
-			cpu-release-addr = <0x0 0x8000fff8>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>;
 		};
 	};
 
-- 
1.8.4