PM / Domains: Add support for CPU devices to genpd

To enable a device belonging to a CPU to be attached to a PM domain managed
by genpd, let's do a few changes to genpd as to make it convenient to
manage the specifics around CPUs.

First, as to be able to quickly find out what CPUs that are attached to a
genpd, which typically becomes useful from a genpd governor as following
changes is about to show, let's add a cpumask 'cpus' to the struct
generic_pm_domain.

At the point when a device that belongs to a CPU, is attached/detached to
its corresponding PM domain via genpd_add_device(), let's update the
cpumask in genpd->cpus. Moreover, propagate the update of the cpumask to
the master domains, which makes the genpd->cpus to contain a cpumask that
hierarchically reflect all CPUs for a genpd, including CPUs attached to
subdomains.

Second, to unconditionally manage CPUs and the cpumask in genpd->cpus, is
unnecessary for cases when only non-CPU devices are parts of a genpd.
Let's avoid this by adding a new configuration bit, GENPD_FLAG_CPU_DOMAIN.
Clients must set the bit before they call pm_genpd_init(), as to instruct
genpd that it shall deal with CPUs and thus manage the cpumask in
genpd->cpus.

Cc: Lina Iyer <ilina@codeaurora.org>
Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

2 files changed, 71 insertions, 1 deletions

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 9aff79d121aa..e178521b2e57 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -19,6 +19,7 @@
 #include <linux/sched.h>
 #include <linux/suspend.h>
 #include <linux/export.h>
+#include <linux/cpu.h>
 
 #include "power.h"
 
@@ -125,6 +126,7 @@ static const struct genpd_lock_ops genpd_spin_ops = {
 #define genpd_is_irq_safe(genpd)	(genpd->flags & GENPD_FLAG_IRQ_SAFE)
 #define genpd_is_always_on(genpd)	(genpd->flags & GENPD_FLAG_ALWAYS_ON)
 #define genpd_is_active_wakeup(genpd)	(genpd->flags & GENPD_FLAG_ACTIVE_WAKEUP)
+#define genpd_is_cpu_domain(genpd)	(genpd->flags & GENPD_FLAG_CPU_DOMAIN)
 
 static inline bool irq_safe_dev_in_no_sleep_domain(struct device *dev,
 		const struct generic_pm_domain *genpd)
@@ -1377,6 +1379,62 @@ static void genpd_free_dev_data(struct device *dev,
 	dev_pm_put_subsys_data(dev);
 }
 
+static void __genpd_update_cpumask(struct generic_pm_domain *genpd,
+				   int cpu, bool set, unsigned int depth)
+{
+	struct gpd_link *link;
+
+	if (!genpd_is_cpu_domain(genpd))
+		return;
+
+	list_for_each_entry(link, &genpd->slave_links, slave_node) {
+		struct generic_pm_domain *master = link->master;
+
+		genpd_lock_nested(master, depth + 1);
+		__genpd_update_cpumask(master, cpu, set, depth + 1);
+		genpd_unlock(master);
+	}
+
+	if (set)
+		cpumask_set_cpu(cpu, genpd->cpus);
+	else
+		cpumask_clear_cpu(cpu, genpd->cpus);
+}
+
+static void genpd_update_cpumask(struct generic_pm_domain *genpd,
+				 struct device *dev, bool set)
+{
+	bool is_cpu = false;
+	int cpu;
+
+	if (!genpd_is_cpu_domain(genpd))
+		return;
+
+	for_each_possible_cpu(cpu) {
+		if (get_cpu_device(cpu) == dev) {
+			is_cpu = true;
+			break;
+		}
+	}
+
+	if (!is_cpu)
+		return;
+
+	__genpd_update_cpumask(genpd, cpu, set, 0);
+}
+
+static void genpd_set_cpumask(struct generic_pm_domain *genpd,
+			      struct device *dev)
+{
+	genpd_update_cpumask(genpd, dev, true);
+}
+
+static void genpd_clear_cpumask(struct generic_pm_domain *genpd,
+				struct device *dev)
+{
+	genpd_update_cpumask(genpd, dev, false);
+}
+
 static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 			    struct gpd_timing_data *td)
 {
@@ -1403,6 +1461,8 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 	if (ret)
 		goto out;
 
+	genpd_set_cpumask(genpd, dev);
+
 	dev_pm_domain_set(dev, &genpd->domain);
 
 	genpd->device_count++;
@@ -1466,6 +1526,7 @@ static int genpd_remove_device(struct generic_pm_domain *genpd,
 	if (genpd->detach_dev)
 		genpd->detach_dev(genpd, dev);
 
+	genpd_clear_cpumask(genpd, dev);
 	dev_pm_domain_set(dev, NULL);
 
 	list_del_init(&pdd->list_node);
@@ -1693,11 +1754,16 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
 	if (genpd_is_always_on(genpd) && !genpd_status_on(genpd))
 		return -EINVAL;
 
+	if (!zalloc_cpumask_var(&genpd->cpus, GFP_KERNEL))
+		return -ENOMEM;
+
 	/* Use only one "off" state if there were no states declared */
 	if (genpd->state_count == 0) {
 		ret = genpd_set_default_power_state(genpd);
-		if (ret)
+		if (ret) {
+			free_cpumask_var(genpd->cpus);
 			return ret;
+		}
 	} else if (!gov) {
 		pr_warn("%s : no governor for states\n", genpd->name);
 	}
@@ -1740,6 +1806,7 @@ static int genpd_remove(struct generic_pm_domain *genpd)
 	list_del(&genpd->gpd_list_node);
 	genpd_unlock(genpd);
 	cancel_work_sync(&genpd->power_off_work);
+	free_cpumask_var(genpd->cpus);
 	kfree(genpd->free);
 	pr_debug("%s: removed %s\n", __func__, genpd->name);
 
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 55ad34db68d3..29ab00cff0ee 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -16,12 +16,14 @@
 #include <linux/of.h>
 #include <linux/notifier.h>
 #include <linux/spinlock.h>
+#include <linux/cpumask.h>
 
 /* Defines used for the flags field in the struct generic_pm_domain */
 #define GENPD_FLAG_PM_CLK	 (1U << 0) /* PM domain uses PM clk */
 #define GENPD_FLAG_IRQ_SAFE	 (1U << 1) /* PM domain operates in atomic */
 #define GENPD_FLAG_ALWAYS_ON	 (1U << 2) /* PM domain is always powered on */
 #define GENPD_FLAG_ACTIVE_WAKEUP (1U << 3) /* Keep devices active if wakeup */
+#define GENPD_FLAG_CPU_DOMAIN	 (1U << 4) /* PM domain manages CPUs */
 
 enum gpd_status {
 	GPD_STATE_ACTIVE = 0,	/* PM domain is active */
@@ -66,6 +68,7 @@ struct generic_pm_domain {
 	unsigned int suspended_count;	/* System suspend device counter */
 	unsigned int prepared_count;	/* Suspend counter of prepared devices */
 	unsigned int performance_state;	/* Aggregated max performance state */
+	cpumask_var_t cpus;		/* A cpumask of the attached CPUs */
 	int (*power_off)(struct generic_pm_domain *domain);
 	int (*power_on)(struct generic_pm_domain *domain);
 	int (*set_performance_state)(struct generic_pm_domain *genpd,