[PATCH v4 06/16] PM / cpu_domains: Setup PM domains for CPUs/clusters

[Lina Iyer]

Define and add Generic PM domains (genpd) for CPU clusters. Many new
SoCs group CPUs as clusters. Clusters share common resources like power
rails, caches, VFP, Coresight etc. When all CPUs in the cluster are
idle, these shared resources may also be put in their idle state.

CPUs may be associated with their domain providers. The domains in
turn may be associated with their providers. This is clean way to model
the cluster hierarchy like that of ARM's big.little architecture.

Platform drivers may initialize generic PM domains and setup the CPU PM
domains for the genpd and attach CPUs to the domain. In the following
patches, the CPUs are hooked up to runtime PM framework which helps
power down the domain, when all the CPUs in the domain are idle.

Cc: Ulf Hansson <ulf.hansson at linaro.org>
Suggested-by: Kevin Hilman <khilman at kernel.org>
Signed-off-by: Lina Iyer <lina.iyer at linaro.org>
---
 drivers/base/power/Makefile      |   1 +
 drivers/base/power/cpu_domains.c | 191 +++++++++++++++++++++++++++++++++++++++
 include/linux/cpu_domains.h      |  49 ++++++++++
 3 files changed, 241 insertions(+)
 create mode 100644 drivers/base/power/cpu_domains.c
 create mode 100644 include/linux/cpu_domains.h

diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index 5998c53..9883e89 100644
--- a/drivers/base/power/Makefile
+++ b/drivers/base/power/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_PM_SLEEP)	+= main.o wakeup.o
 obj-$(CONFIG_PM_TRACE_RTC)	+= trace.o
 obj-$(CONFIG_PM_OPP)	+= opp/
 obj-$(CONFIG_PM_GENERIC_DOMAINS)	+=  domain.o domain_governor.o
+obj-$(CONFIG_PM_GENERIC_DOMAINS_OF)	+= cpu_domains.o
 obj-$(CONFIG_HAVE_CLK)	+= clock_ops.o
 
 ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
diff --git a/drivers/base/power/cpu_domains.c b/drivers/base/power/cpu_domains.c
new file mode 100644
index 0000000..73e493b
--- /dev/null
+++ b/drivers/base/power/cpu_domains.c
@@ -0,0 +1,191 @@
+/*
+ * drivers/base/power/cpu_domains.c - Helper functions to create CPU PM domains.
+ *
+ * Copyright (C) 2016 Linaro Ltd.
+ *
+ * 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/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/cpu_domains.h>
+#include <linux/cpu_pm.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/pm_domain.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+#include <linux/slab.h>
+
+#define CPU_PD_NAME_MAX 36
+
+struct cpu_pm_domain {
+	struct list_head link;
+	struct cpu_pd_ops ops;
+	struct generic_pm_domain *genpd;
+	struct cpu_pm_domain *parent;
+	cpumask_var_t cpus;
+};
+
+/* List of CPU PM domains we care about */
+static LIST_HEAD(of_cpu_pd_list);
+static DEFINE_MUTEX(cpu_pd_list_lock);
+
+static inline struct cpu_pm_domain *to_cpu_pd(struct generic_pm_domain *d)
+{
+	struct cpu_pm_domain *pd;
+	struct cpu_pm_domain *res = NULL;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(pd, &of_cpu_pd_list, link)
+		if (pd->genpd == d) {
+			res = pd;
+			break;
+		}
+	rcu_read_unlock();
+
+	return res;
+}
+
+static int cpu_pd_power_on(struct generic_pm_domain *genpd)
+{
+	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
+
+	return pd->ops.power_on ? pd->ops.power_on() : 0;
+}
+
+static int cpu_pd_power_off(struct generic_pm_domain *genpd)
+{
+	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
+
+	return pd->ops.power_off ? pd->ops.power_off(genpd->state_idx,
+					genpd->states[genpd->state_idx].param,
+					pd->cpus) : 0;
+}
+
+/**
+ * cpu_pd_attach_domain:  Attach a child CPU PM to its parent
+ *
+ * @parent: The parent generic PM domain
+ * @child: The child generic PM domain
+ *
+ * Generally, the child PM domain is the one to which CPUs are attached.
+ */
+int cpu_pd_attach_domain(struct generic_pm_domain *parent,
+				struct generic_pm_domain *child)
+{
+	struct cpu_pm_domain *cpu_pd, *parent_cpu_pd;
+	int ret;
+
+	ret = pm_genpd_add_subdomain(parent, child);
+	if (ret) {
+		pr_err("%s: Unable to add sub-domain (%s) to %s.\n err=%d",
+				__func__, child->name, parent->name, ret);
+		return ret;
+	}
+
+	cpu_pd = to_cpu_pd(child);
+	parent_cpu_pd = to_cpu_pd(parent);
+
+	if (cpu_pd && parent_cpu_pd)
+		cpu_pd->parent = parent_cpu_pd;
+
+	return ret;
+}
+EXPORT_SYMBOL(cpu_pd_attach_domain);
+
+/**
+ * cpu_pd_attach_cpu:  Attach a CPU to its CPU PM domain.
+ *
+ * @genpd: The parent generic PM domain
+ * @cpu: The CPU number
+ */
+int cpu_pd_attach_cpu(struct generic_pm_domain *genpd, int cpu)
+{
+	int ret;
+	struct device *cpu_dev;
+	struct cpu_pm_domain *cpu_pd = to_cpu_pd(genpd);
+
+	cpu_dev = get_cpu_device(cpu);
+	if (!cpu_dev) {
+		pr_warn("%s: Unable to get device for CPU%d\n",
+				__func__, cpu);
+		return -ENODEV;
+	}
+
+	ret = genpd_dev_pm_attach(cpu_dev);
+	if (ret)
+		dev_warn(cpu_dev,
+			"%s: Unable to attach to power-domain: %d\n",
+			__func__, ret);
+	else
+		dev_dbg(cpu_dev, "Attached to domain\n");
+
+	while (!ret && cpu_pd) {
+		cpumask_set_cpu(cpu, cpu_pd->cpus);
+		cpu_pd = cpu_pd->parent;
+	};
+
+	return ret;
+}
+EXPORT_SYMBOL(cpu_pd_attach_cpu);
+
+/**
+ * cpu_pd_init: Initialize a CPU PM domain for a genpd
+ *
+ * @genpd: The initialized generic PM domain object.
+ * @ops: The power_on/power_off ops for the domain controller.
+ *
+ * Initialize a CPU PM domain based on a generic PM domain. The platform driver
+ * is expected to setup the genpd object and the states associated with the
+ * generic PM domain, before calling this function.
+ */
+struct generic_pm_domain *cpu_pd_init(struct generic_pm_domain *genpd,
+				const struct cpu_pd_ops *ops)
+{
+	int ret = -ENOMEM;
+	struct cpu_pm_domain *pd;
+
+	if (IS_ERR_OR_NULL(genpd))
+		return ERR_PTR(-EINVAL);
+
+	pd = kzalloc(sizeof(*pd), GFP_KERNEL);
+	if (!pd)
+		goto fail;
+
+	if (!zalloc_cpumask_var(&pd->cpus, GFP_KERNEL))
+		goto fail;
+
+	genpd->power_off = cpu_pd_power_off;
+	genpd->power_on = cpu_pd_power_on;
+	genpd->flags |= GENPD_FLAG_IRQ_SAFE;
+	pd->genpd = genpd;
+	pd->ops.power_on = ops->power_on;
+	pd->ops.power_off = ops->power_off;
+
+	INIT_LIST_HEAD_RCU(&pd->link);
+	mutex_lock(&cpu_pd_list_lock);
+	list_add_rcu(&pd->link, &of_cpu_pd_list);
+	mutex_unlock(&cpu_pd_list_lock);
+
+	ret = pm_genpd_init(genpd, &simple_qos_governor, false);
+	if (ret) {
+		pr_err("Unable to initialize domain %s\n", genpd->name);
+		goto fail;
+	}
+
+	pr_debug("adding %s as CPU PM domain\n", pd->genpd->name);
+
+	return genpd;
+fail:
+	kfree(genpd->name);
+	kfree(genpd);
+	if (pd)
+		kfree(pd->cpus);
+	kfree(pd);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(cpu_pd_init);
diff --git a/include/linux/cpu_domains.h b/include/linux/cpu_domains.h
new file mode 100644
index 0000000..3a0a027
--- /dev/null
+++ b/include/linux/cpu_domains.h
@@ -0,0 +1,49 @@
+/*
+ * include/linux/cpu_domains.h
+ *
+ * Copyright (C) 2016 Linaro Ltd.
+ *
+ * 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.
+ */
+
+#ifndef __CPU_DOMAINS_H__
+#define __CPU_DOMAINS_H__
+
+#include <linux/types.h>
+
+struct cpumask;
+
+struct cpu_pd_ops {
+	int (*power_off)(u32 state_idx, u32 param, const struct cpumask *mask);
+	int (*power_on)(void);
+};
+
+#ifdef CONFIG_PM_GENERIC_DOMAINS
+
+struct generic_pm_domain *cpu_pd_init(struct generic_pm_domain *genpd,
+				const struct cpu_pd_ops *ops);
+
+int cpu_pd_attach_domain(struct generic_pm_domain *parent,
+				struct generic_pm_domain *child);
+
+int cpu_pd_attach_cpu(struct generic_pm_domain *genpd, int cpu);
+
+#else
+
+static inline
+struct generic_pm_domain *cpu_pd_init(struct generic_pm_domain *genpd,
+				const struct cpu_pd_ops *ops)
+{ return ERR_PTR(-ENODEV); }
+
+static inline int cpu_pd_attach_domain(struct generic_pm_domain *parent,
+				struct generic_pm_domain *child)
+{ return -ENODEV; }
+
+static inline int cpu_pd_attach_cpu(struct generic_pm_domain *genpd, int cpu)
+{ return -ENODEV; }
+
+#endif /* CONFIG_PM_GENERIC_DOMAINS */
+
+#endif /* __CPU_DOMAINS_H__ */
-- 
2.7.4