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Subject[PATCH v12 2/4] PM / Domains: Add support for CPU devices to genpd
Date
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 it, as to make it convenient to manage
the specifics around CPUs.

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 to the struct generic_pm_domain. At
the point when a CPU device gets attached to a genpd, let's update the
genpd's cpumask. Moreover, let's also propagate changes to the cpumask
upwards in the topology to the master PM domains. In this way, the cpumask
for a genpd hierarchically reflects all CPUs attached to the topology below
it.

Finally, let's make this an opt-in feature, to avoid having to manage CPUs
and the cpumask for a genpd that doesn't need it. For that reason, let's
add a new genpd configuration bit, GENPD_FLAG_CPU_DOMAIN.

Cc: Lina Iyer <ilina@codeaurora.org>
Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---

Changes in v12:
- None.

---
drivers/base/power/domain.c | 66 ++++++++++++++++++++++++++++++++++++-
include/linux/pm_domain.h | 13 ++++++++
2 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 03885c003c6a..da10052e6427 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -20,6 +20,7 @@
#include <linux/sched.h>
#include <linux/suspend.h>
#include <linux/export.h>
+#include <linux/cpu.h>

#include "power.h"

@@ -126,6 +127,7 @@ 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)
@@ -1452,6 +1454,56 @@ 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)
{
@@ -1473,6 +1525,8 @@ 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++;
@@ -1534,6 +1588,7 @@ 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);
@@ -1767,11 +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) {
pr_warn("%s : no governor for states\n", genpd->name);
}
@@ -1817,6 +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 8e1399231753..a6e251fe9deb 100644
--- 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 */
--
2.17.1
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