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Subject[PATCH v6 05/25] PM / Domains: Add helper functions to attach/detach CPUs to/from genpd
Date
Introduce two new genpd helper functions, of_genpd_attach|detach_cpu(),
which takes the CPU-number as an in-parameter.

To attach a CPU to a genpd, of_genpd_attach_cpu() starts by fetching the
struct device belonging to the CPU. Then it calls genpd_dev_pm_attach(),
which via DT tries to hook up the CPU device to its corresponding PM
domain. If it succeeds, of_genpd_attach_cpu() continues to prepare/enable
runtime PM of the device.

To detach a CPU from its PM domain, of_genpd_attach_cpu() reverse the
operations made from of_genpd_attach_cpu(). However, first it checks that
the CPU device has a valid PM domain pointer assigned, as to make sure it
belongs to genpd.

Cc: Lina Iyer <ilina@codeaurora.org>
Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
drivers/base/power/domain.c | 67 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/pm_domain.h | 9 ++++++
2 files changed, 76 insertions(+)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index e178521..91ea9b2 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -2324,6 +2324,73 @@ int genpd_dev_pm_attach(struct device *dev)
}
EXPORT_SYMBOL_GPL(genpd_dev_pm_attach);

+/**
+ * of_genpd_attach_cpu() - Attach a CPU to its PM domain
+ * @cpu: The CPU to be attached.
+ *
+ * Try to find the corresponding PM domain provider for the CPU's device. Use
+ * it to attach the CPU's device to its PM domain. If attaching is completed
+ * successfully, we enable runtime PM for the CPU's device.
+ *
+ * Returns zero on success else a negative error code.
+ */
+int of_genpd_attach_cpu(int cpu)
+{
+ struct device *dev = get_cpu_device(cpu);
+ int ret;
+
+ if (!dev) {
+ pr_warn("genpd: no dev for cpu%d\n", cpu);
+ return -ENODEV;
+ }
+
+ ret = genpd_dev_pm_attach(dev);
+ if (ret) {
+ dev_warn(dev, "genpd: attach cpu failed %d\n", ret);
+ return ret;
+ }
+
+ pm_runtime_irq_safe(dev);
+ pm_runtime_get_noresume(dev);
+ pm_runtime_set_active(dev);
+ pm_runtime_enable(dev);
+
+ dev_info(dev, "genpd: attached cpu\n");
+ return 0;
+}
+EXPORT_SYMBOL(of_genpd_attach_cpu);
+
+/**
+ * of_genpd_detach_cpu() - Detach a CPU from its PM domain
+ * @cpu: The CPU to be detached.
+ *
+ * Detach the CPU's device from its corresponding PM domain. If detaching is
+ * completed successfully, disable runtime PM and restore the runtime PM usage
+ * count for the CPU's device.
+ */
+void of_genpd_detach_cpu(int cpu)
+{
+ struct device *dev = get_cpu_device(cpu);
+
+ if (!dev) {
+ pr_warn("genpd: no dev for cpu%d\n", cpu);
+ return;
+ }
+
+ /* Check that the device is attached to a genpd. */
+ if (!(dev->pm_domain && dev->pm_domain->detach == genpd_dev_pm_detach))
+ return;
+
+ genpd_dev_pm_detach(dev, true);
+
+ pm_runtime_disable(dev);
+ pm_runtime_put_noidle(dev);
+ pm_runtime_reinit(dev);
+
+ dev_info(dev, "genpd: detached cpu\n");
+}
+EXPORT_SYMBOL(of_genpd_detach_cpu);
+
static const struct of_device_id idle_state_match[] = {
{ .compatible = "domain-idle-state", },
{ }
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 29ab00c..ccd7c94 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -249,6 +249,8 @@ extern int of_genpd_parse_idle_states(struct device_node *dn,
struct genpd_power_state **states, int *n);

int genpd_dev_pm_attach(struct device *dev);
+int of_genpd_attach_cpu(int cpu);
+void of_genpd_detach_cpu(int cpu);
#else /* !CONFIG_PM_GENERIC_DOMAINS_OF */
static inline int of_genpd_add_provider_simple(struct device_node *np,
struct generic_pm_domain *genpd)
@@ -287,6 +289,13 @@ static inline int genpd_dev_pm_attach(struct device *dev)
return -ENODEV;
}

+static inline int of_genpd_attach_cpu(int cpu)
+{
+ return -ENODEV;
+}
+
+static inline void of_genpd_detach_cpu(int cpu) {}
+
static inline
struct generic_pm_domain *of_genpd_remove_last(struct device_node *np)
{
--
2.7.4
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