[RFC,v2,03/12] PM / cpu_domains: Setup PM domains for CPUs/clusters

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..981592f
--- /dev/null
+++ b/drivers/base/power/cpu_domains.c
@@ -0,0 +1,267 @@ 
+/*
+ * 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/cpu_domains.h>
+#include <linux/cpu_pm.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/of.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;
+};
+
+/* List of CPU PM domains we care about */
+static LIST_HEAD(of_cpu_pd_list);
+static DEFINE_SPINLOCK(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_attach_cpu(int cpu)
+{
+	int ret;
+	struct device *cpu_dev;
+
+	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");
+
+	return ret;
+}
+
+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();
+}
+
+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(genpd->state_idx,
+			genpd->states[genpd->state_idx].param);
+}
+
+/**
+ * of_init_cpu_pm_domain() - Initialize a CPU PM domain from a device node
+ *
+ * @dn: The domain provider's device node
+ * @ops: The power_on/_off callbacks for the domain
+ *
+ * Returns the generic_pm_domain (genpd) pointer to the domain on success
+ */
+static struct generic_pm_domain *of_init_cpu_pm_domain(struct device_node *dn,
+				const struct cpu_pd_ops *ops)
+{
+	struct cpu_pm_domain *pd = NULL;
+	struct generic_pm_domain *genpd = NULL;
+	int ret = -ENOMEM;
+
+	if (!of_device_is_available(dn))
+		return ERR_PTR(-ENODEV);
+
+	genpd = kzalloc(sizeof(*(genpd)), GFP_KERNEL);
+	if (!genpd)
+		goto fail;
+
+	genpd->name = kstrndup(dn->full_name, CPU_PD_NAME_MAX, GFP_KERNEL);
+	if (!genpd->name)
+		goto fail;
+
+	pd = kzalloc(sizeof(*pd), GFP_KERNEL);
+	if (!pd)
+		goto fail;
+
+	pd->genpd = genpd;
+	pd->genpd->power_off = cpu_pd_power_off;
+	pd->genpd->power_on = cpu_pd_power_on;
+	pd->genpd->flags |= GENPD_FLAG_IRQ_SAFE;
+	pd->ops.power_on = ops->power_on;
+	pd->ops.power_off = ops->power_off;
+
+	INIT_LIST_HEAD_RCU(&pd->link);
+	spin_lock(&cpu_pd_list_lock);
+	list_add_rcu(&pd->link, &of_cpu_pd_list);
+	spin_unlock(&cpu_pd_list_lock);
+
+	/* Register the CPU genpd */
+	pr_debug("adding %s as CPU PM domain.\n", pd->genpd->name);
+	ret = of_pm_genpd_init(dn, pd->genpd, &simple_qos_governor, false);
+	if (ret) {
+		pr_err("Unable to initialize domain %s\n", dn->full_name);
+		goto fail;
+	}
+
+	ret = of_genpd_add_provider_simple(dn, pd->genpd);
+	if (ret)
+		pr_warn("Unable to add genpd %s as provider\n",
+				pd->genpd->name);
+
+	return pd->genpd;
+fail:
+
+	kfree(genpd);
+	kfree(genpd->name);
+	kfree(pd);
+	return ERR_PTR(ret);
+}
+
+static struct generic_pm_domain *of_get_cpu_domain(struct device_node *dn,
+		const struct cpu_pd_ops *ops, int cpu)
+{
+	struct of_phandle_args args;
+	struct generic_pm_domain *genpd, *parent;
+	int ret;
+
+	/* Do we have this domain? If not, create the domain */
+	args.np = dn;
+	args.args_count = 0;
+
+	genpd = of_genpd_get_from_provider(&args);
+	if (!IS_ERR(genpd))
+		goto skip_parent;
+
+	genpd = of_init_cpu_pm_domain(dn, ops);
+	if (IS_ERR(genpd))
+		return genpd;
+
+	/* Is there a domain provider for this domain? */
+	ret = of_parse_phandle_with_args(dn, "power-domains",
+			"#power-domain-cells", 0, &args);
+	of_node_put(dn);
+	if (ret < 0)
+		goto skip_parent;
+
+	/* Find its parent and attach this domain to it, recursively */
+	parent = of_get_cpu_domain(args.np, ops, cpu);
+	if (IS_ERR(parent)) {
+		struct cpu_pm_domain *cpu_pd, *parent_cpu_pd;
+
+		ret = pm_genpd_add_subdomain(genpd, parent);
+		if (ret) {
+			pr_err("%s: Unable to add sub-domain (%s) to parent (%s)\n err: %d",
+					__func__, genpd->name, parent->name,
+					ret);
+			return ERR_PTR(ret);
+		}
+
+		/*
+		 * Reference parent domain for easy access.
+		 * Note: We could be attached to a domain that is not a
+		 * CPU PM domain in that case dont reference the parent.
+		 */
+		cpu_pd = to_cpu_pd(genpd);
+		parent_cpu_pd = to_cpu_pd(parent);
+
+		if (cpu_pd && parent_cpu_pd)
+			cpu_pd->parent = parent_cpu_pd;
+	}
+
+skip_parent:
+	return genpd;
+}
+
+/**
+ * of_setup_cpu_pd_single() - Setup the PM domains for a CPU
+ *
+ * @cpu: The CPU for which the PM domain is to be set up.
+ * @ops: The PM domain suspend/resume ops for the CPU's domain
+ *
+ * If the CPU PM domain exists already, then the CPU is attached to
+ * that CPU PD. If it doesn't, the domain is created, the @ops are
+ * set for power_on/power_off callbacks and then the CPU is attached
+ * to that domain. If the domain was created outside this framework,
+ * then we do not attach the CPU to the domain.
+ */
+int of_setup_cpu_pd_single(int cpu, const struct cpu_pd_ops *ops)
+{
+
+	struct device_node *dn;
+	struct generic_pm_domain *genpd;
+
+	dn = of_get_cpu_node(cpu, NULL);
+	if (!dn)
+		return -ENODEV;
+
+	dn = of_parse_phandle(dn, "power-domains", 0);
+	if (!dn)
+		return -ENODEV;
+	of_node_put(dn);
+
+	/* Find the genpd for this CPU, create if not found */
+	genpd = of_get_cpu_domain(dn, ops, cpu);
+	if (IS_ERR(genpd))
+		return PTR_ERR(genpd);
+
+	return cpu_pd_attach_cpu(cpu);
+}
+EXPORT_SYMBOL(of_setup_cpu_pd_single);
+
+/**
+ * of_setup_cpu_pd() - Setup the PM domains for all CPUs
+ *
+ * @ops: The PM domain suspend/resume ops for all the domains
+ *
+ * Setup the CPU PM domain and attach all possible CPUs to their respective
+ * domains. The domains are created if not already and then attached.
+ */
+int of_setup_cpu_pd(const struct cpu_pd_ops *ops)
+{
+	int cpu;
+	int ret;
+
+	for_each_possible_cpu(cpu) {
+		ret = of_setup_cpu_pd_single(cpu, ops);
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(of_setup_cpu_pd);
diff --git a/include/linux/cpu_domains.h b/include/linux/cpu_domains.h
new file mode 100644
index 0000000..bab4846
--- /dev/null
+++ b/include/linux/cpu_domains.h
@@ -0,0 +1,33 @@ 
+/*
+ * 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__
+
+struct cpu_pd_ops {
+	int (*power_off)(u32 state_idx, u32 param);
+	int (*power_on)(void);
+};
+
+#ifdef CONFIG_PM_GENERIC_DOMAINS_OF
+int of_setup_cpu_pd_single(int cpu, const struct cpu_pd_ops *ops);
+int of_setup_cpu_pd(const struct cpu_pd_ops *ops);
+#else
+static inline int of_setup_cpu_pd_single(int cpu, const struct cpu_pd_ops *ops)
+{
+	return -ENODEV;
+}
+static inline int of_setup_cpu_pd(const struct cpu_pd_ops *ops)
+{
+	return -ENODEV;
+}
+#endif /* CONFIG_PM_GENERIC_DOMAINS_OF */
+
+#endif /* __CPU_DOMAINS_H__ */