PM / Domains: Add support for CPU devices to genpd

To enable a CPU device to be attached to a PM domain managed by genpd,
make a few changes to it for convenience.

To be able to quickly find out what CPUs are attached to a genpd,
which typically becomes useful from a genpd governor as subsequent
changes are about to show, add a cpumask to struct generic_pm_domain
to be updated when a CPU device gets attached to the genpd containing
that cpumask. Also, propagate the cpumask changes upwards in the
domain hierarchy to the master PM domains. This way, the cpumask for
a genpd hierarchically reflects all CPUs attached to the topology
below it.

Finally, make this an opt-in feature, to avoid having to manage CPUs
and the cpumask for a genpd that don't need it. To that end, add
a new genpd configuration bit, GENPD_FLAG_CPU_DOMAIN.

Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index ff6f992..ecac03d 100644 (file)
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -22,6 +22,7 @@
 #include <linux/sched.h>
 #include <linux/suspend.h>
 #include <linux/export.h>
+#include <linux/cpu.h>
 
 #include "power.h"
 
@@ -128,6 +129,7 @@ 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)
@@ -1454,6 +1456,56 @@ 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)
+{
+       int cpu;
+
+       if (!genpd_is_cpu_domain(genpd))
+               return;
+
+       for_each_possible_cpu(cpu) {
+               if (get_cpu_device(cpu) == dev) {
+                       __genpd_update_cpumask(genpd, cpu, set, 0);
+                       return;
+               }
+       }
+}
+
+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)
 {
@@ -1475,6 +1527,7 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 
        genpd_lock(genpd);
 
+       genpd_set_cpumask(genpd, dev);
        dev_pm_domain_set(dev, &genpd->domain);
 
        genpd->device_count++;
@@ -1532,6 +1585,7 @@ static int genpd_remove_device(struct generic_pm_domain *genpd,
        genpd->device_count--;
        genpd->max_off_time_changed = true;
 
+       genpd_clear_cpumask(genpd, dev);
        dev_pm_domain_set(dev, NULL);
 
        list_del_init(&pdd->list_node);
@@ -1768,11 +1822,18 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
        if (genpd_is_always_on(genpd) && !genpd_status_on(genpd))
                return -EINVAL;
 
+       if (genpd_is_cpu_domain(genpd) &&
+           !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) {
+                       if (genpd_is_cpu_domain(genpd))
+                               free_cpumask_var(genpd->cpus);
                        return ret;
+               }
        } else if (!gov && genpd->state_count > 1) {
                pr_warn("%s: no governor for states\n", genpd->name);
        }
@@ -1818,6 +1879,8 @@ 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);
+       if (genpd_is_cpu_domain(genpd))
+               free_cpumask_var(genpd->cpus);
        if (genpd->free_states)
                genpd->free_states(genpd->states, genpd->state_count);
 

diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 8e13992..a6e251f 100644 (file)
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -16,6 +16,7 @@
 #include <linux/of.h>
 #include <linux/notifier.h>
 #include <linux/spinlock.h>
+#include <linux/cpumask.h>
 
 /*
  * Flags to control the behaviour of a genpd.
@@ -42,11 +43,22 @@
  * GENPD_FLAG_ACTIVE_WAKEUP:   Instructs genpd to keep the PM domain powered
  *                             on, in case any of its attached devices is used
  *                             in the wakeup path to serve system wakeups.
+ *
+ * GENPD_FLAG_CPU_DOMAIN:      Instructs genpd that it should expect to get
+ *                             devices attached, which may belong to CPUs or
+ *                             possibly have subdomains with CPUs attached.
+ *                             This flag enables the genpd backend driver to
+ *                             deploy idle power management support for CPUs
+ *                             and groups of CPUs. Note that, the backend
+ *                             driver must then comply with the so called,
+ *                             last-man-standing algorithm, for the CPUs in the
+ *                             PM domain.
  */
 #define GENPD_FLAG_PM_CLK       (1U << 0)
 #define GENPD_FLAG_IRQ_SAFE     (1U << 1)
 #define GENPD_FLAG_ALWAYS_ON    (1U << 2)
 #define GENPD_FLAG_ACTIVE_WAKEUP (1U << 3)
+#define GENPD_FLAG_CPU_DOMAIN   (1U << 4)
 
 enum gpd_status {
        GPD_STATE_ACTIVE = 0,   /* PM domain is active */
@@ -94,6 +106,7 @@ 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);
        struct opp_table *opp_table;    /* OPP table of the genpd */