PM / Domains: Add support for removing PM domains

The genpd framework allows users to add PM domains via the pm_genpd_init()
function, however, there is no corresponding function to remove a PM
domain. For most devices this may be fine as the PM domains are never
removed, however, for devices that wish to populate the PM domains from
within a driver, having the ability to remove a PM domain if the probing
of the device fails or the driver is unloaded is necessary.

Add the function pm_genpd_remove() to remove a PM domain by referencing
it's generic_pm_domain structure. Note that the bulk of the code that
removes the PM domain is placed in a separate local function
genpd_remove() (which is called by pm_genpd_remove()). The code is
structured in this way to prepare for adding another function to remove
a PM domain by provider that will also call genpd_remove(). Note that
users of genpd_remove() must call this function with the mutex,
gpd_list_lock, held.

PM domains can only be removed if the associated provider has been
removed, they are not a parent domain to another PM domain and have no
devices associated with them.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
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 d5135ca..7481e3e 100644 (file)
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -1358,6 +1358,66 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
 }
 EXPORT_SYMBOL_GPL(pm_genpd_init);
 
+static int genpd_remove(struct generic_pm_domain *genpd)
+{
+       struct gpd_link *l, *link;
+
+       if (IS_ERR_OR_NULL(genpd))
+               return -EINVAL;
+
+       mutex_lock(&genpd->lock);
+
+       if (genpd->has_provider) {
+               mutex_unlock(&genpd->lock);
+               pr_err("Provider present, unable to remove %s\n", genpd->name);
+               return -EBUSY;
+       }
+
+       if (!list_empty(&genpd->master_links) || genpd->device_count) {
+               mutex_unlock(&genpd->lock);
+               pr_err("%s: unable to remove %s\n", __func__, genpd->name);
+               return -EBUSY;
+       }
+
+       list_for_each_entry_safe(link, l, &genpd->slave_links, slave_node) {
+               list_del(&link->master_node);
+               list_del(&link->slave_node);
+               kfree(link);
+       }
+
+       list_del(&genpd->gpd_list_node);
+       mutex_unlock(&genpd->lock);
+       cancel_work_sync(&genpd->power_off_work);
+       pr_debug("%s: removed %s\n", __func__, genpd->name);
+
+       return 0;
+}
+
+/**
+ * pm_genpd_remove - Remove a generic I/O PM domain
+ * @genpd: Pointer to PM domain that is to be removed.
+ *
+ * To remove the PM domain, this function:
+ *  - Removes the PM domain as a subdomain to any parent domains,
+ *    if it was added.
+ *  - Removes the PM domain from the list of registered PM domains.
+ *
+ * The PM domain will only be removed, if the associated provider has
+ * been removed, it is not a parent to any other PM domain and has no
+ * devices associated with it.
+ */
+int pm_genpd_remove(struct generic_pm_domain *genpd)
+{
+       int ret;
+
+       mutex_lock(&gpd_list_lock);
+       ret = genpd_remove(genpd);
+       mutex_unlock(&gpd_list_lock);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(pm_genpd_remove);
+
 #ifdef CONFIG_PM_GENERIC_DOMAINS_OF
 
 typedef struct generic_pm_domain *(*genpd_xlate_t)(struct of_phandle_args *args,

diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 554f891..85f7d53 100644 (file)
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -130,6 +130,7 @@ extern int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
                                     struct generic_pm_domain *target);
 extern int pm_genpd_init(struct generic_pm_domain *genpd,
                         struct dev_power_governor *gov, bool is_off);
+extern int pm_genpd_remove(struct generic_pm_domain *genpd);
 
 extern struct dev_power_governor simple_qos_governor;
 extern struct dev_power_governor pm_domain_always_on_gov;
@@ -165,6 +166,10 @@ static inline int pm_genpd_init(struct generic_pm_domain *genpd,
 {
        return -ENOSYS;
 }
+static inline int pm_genpd_remove(struct generic_pm_domain *genpd)
+{
+       return -ENOTSUPP;
+}
 #endif
 
 static inline int pm_genpd_add_device(struct generic_pm_domain *genpd,