[PATCH 03/12] PM / Domains: Add notifier support for power domain transitions
Ulf Hansson
ulf.hansson at linaro.org
Mon Nov 3 06:52:55 PST 2014
On 3 November 2014 15:54, Rafael J. Wysocki <rjw at rjwysocki.net> wrote:
> CC: Kevin, Ulf, Geert.
>
> On Monday, November 03, 2014 09:23:01 AM Amit Daniel Kachhap wrote:
>> These power domain transition notifiers will assist in carrying
>> out some activity associated with domain power on/off such as
>> some registers which may lose its contents and need save/restore
>> across domain power off/on.
Hi Amit,
This mechanism seems to be needed - somehow.
A similar approach has been posted earlier, I am not sure that
discussion was fully settled though.
http://marc.info/?l=linux-pm&m=136448756308203&w=2
Anyway, I plan to review this shortly.
Kind regards
Uffe
>>
>> 4 type of notifications are added,
>> GPD_OFF_PRE - GPD state before power off
>> GPD_OFF_POST - GPD state after power off
>> GPD_ON_PRE - GPD state before power off
>> GPD_ON_POST - GPD state after power off
>>
>> 3 notfication API's are exported.
>> 1) int genpd_register_notifier(struct notifier_block *nb, char *pd_name);
>> 2) int genpd_unregister_notifier(struct notifier_block *nb, char *pd_name);
>> 3) void genpd_invoke_transition_notifier(struct generic_pm_domain *genpd,
>> enum gpd_on_off_state state);
>>
>> In this approach the notifiers are registered/unregistered with pd name.
>> The actual invoking of the notfiers will be done by the platform implementing
>> power domain enable/disable low level handlers according to the above
>> defined notification types. This approach will considerably reduce the
>> number of call to notifiers as compared to calling always from core
>> powerdomain subsystem.
>>
>> Also the registered domain's will be managed inside a cache list and not
>> part of the genpd structure. This will help in registration of notifiers from
>> subsystems (such as clock) even when the PD subsystem is still not initialised.
>> This list also filters out the unregistered pd's requesting notification.
>>
>> Cc: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
>> Reviewed-by: Pankaj Dubey <pankaj.dubey at samsung.com>
>> Signed-off-by: Amit Daniel Kachhap <amit.daniel at samsung.com>
>> ---
>> drivers/base/power/domain.c | 112 ++++++++++++++++++++++++++++++++++++++++++-
>> include/linux/pm_domain.h | 31 ++++++++++++
>> 2 files changed, 142 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
>> index 40bc2f4..e05045e 100644
>> --- a/drivers/base/power/domain.c
>> +++ b/drivers/base/power/domain.c
>> @@ -46,10 +46,19 @@
>> __retval; \
>> })
>>
>> +struct cache_notify_domains {
>> + char *name;
>> + /* Node in the cache pm domain name list */
>> + struct list_head cache_list_node;
>> +};
>> +
>> static LIST_HEAD(gpd_list);
>> static DEFINE_MUTEX(gpd_list_lock);
>> +static LIST_HEAD(domain_notify_list);
>> +static DEFINE_MUTEX(domain_notify_list_lock);
>> +static BLOCKING_NOTIFIER_HEAD(genpd_transition_notifier_list);
>>
>> -static struct generic_pm_domain *pm_genpd_lookup_name(const char *domain_name)
>> +struct generic_pm_domain *pm_genpd_lookup_name(const char *domain_name)
>> {
>> struct generic_pm_domain *genpd = NULL, *gpd;
>>
>> @@ -66,6 +75,7 @@ static struct generic_pm_domain *pm_genpd_lookup_name(const char *domain_name)
>> mutex_unlock(&gpd_list_lock);
>> return genpd;
>> }
>> +EXPORT_SYMBOL_GPL(pm_genpd_lookup_name);
>>
>> struct generic_pm_domain *dev_to_genpd(struct device *dev)
>> {
>> @@ -1908,6 +1918,106 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
>> mutex_unlock(&gpd_list_lock);
>> }
>>
>> +/**
>> + * genpd_register_notifier - Register a PM domain for future notification.
>> + * @nb: notification block containing notification handle.
>> + * @pd_name: PM domain name.
>> + */
>> +int genpd_register_notifier(struct notifier_block *nb, char *pd_name)
>> +{
>> + int ret;
>> + struct cache_notify_domains *entry;
>> +
>> + if (!pd_name)
>> + return -EINVAL;
>> +
>> + /* Search if the pd is already registered */
>> + mutex_lock(&domain_notify_list_lock);
>> + list_for_each_entry(entry, &domain_notify_list, cache_list_node) {
>> + if (!strcmp(entry->name, pd_name))
>> + break;
>> + }
>> + mutex_unlock(&domain_notify_list_lock);
>> +
>> + if (entry) {
>> + pr_err("%s: pd already exists\n", __func__);
>> + return -EINVAL;
>> + }
>> +
>> + entry = kzalloc(sizeof(*entry), GFP_KERNEL);
>> + if (!entry)
>> + return -ENOMEM;
>> +
>> + entry->name = pd_name;
>> +
>> + mutex_lock(&domain_notify_list_lock);
>> + list_add(&entry->cache_list_node, &domain_notify_list);
>> + mutex_unlock(&domain_notify_list_lock);
>> + ret = blocking_notifier_chain_register(
>> + &genpd_transition_notifier_list, nb);
>> + return ret;
>> +}
>> +
>> +/**
>> + * genpd_unregister_notifier - Un-register a PM domain for future notification.
>> + * @nb: notification block containing notification handle.
>> + * @pd_name: PM domain name.
>> + */
>> +int genpd_unregister_notifier(struct notifier_block *nb, char *pd_name)
>> +{
>> + int ret;
>> + struct cache_notify_domains *entry;
>> +
>> + mutex_lock(&domain_notify_list_lock);
>> + list_for_each_entry(entry, &domain_notify_list, cache_list_node) {
>> + if (!strcmp(entry->name, pd_name))
>> + break;
>> + }
>> + if (!entry) {
>> + mutex_unlock(&domain_notify_list_lock);
>> + pr_err("%s: Invalid pd name\n", __func__);
>> + return -EINVAL;
>> + }
>> + list_del(&entry->cache_list_node);
>> + mutex_unlock(&domain_notify_list_lock);
>> + ret = blocking_notifier_chain_unregister(
>> + &genpd_transition_notifier_list, nb);
>> + return ret;
>> +}
>> +
>> +/**
>> + * genpd_invoke_transition_notifier - Calls the matching notification handler.
>> + * @genpd: generic power domain structure.
>> + * @state: can be of type - GPD_OFF_PRE/GPD_OFF_POST/GPD_ON_PRE/GPD_ON_POST.
>> + */
>> +void genpd_invoke_transition_notifier(struct generic_pm_domain *genpd,
>> + enum gpd_on_off_state state)
>> +{
>> + struct cache_notify_domains *entry;
>> +
>> + if (!genpd) {
>> + pr_err("Invalid genpd parameter\n");
>> + return;
>> + }
>> +
>> + if (state != GPD_OFF_PRE || state != GPD_OFF_POST
>> + || state != GPD_ON_PRE || state != GPD_ON_POST) {
>> + pr_err("Invalid state parameter\n");
>> + return;
>> + }
>> +
>> + mutex_lock(&domain_notify_list_lock);
>> + list_for_each_entry(entry, &domain_notify_list, cache_list_node) {
>> + if (!strcmp(entry->name, genpd->name))
>> + break;
>> + }
>> + mutex_unlock(&domain_notify_list_lock);
>> + if (!entry) /* Simply ignore */
>> + return;
>> +
>> + blocking_notifier_call_chain(&genpd_transition_notifier_list, state,
>> + genpd);
>> +}
>> #ifdef CONFIG_PM_GENERIC_DOMAINS_OF
>> /*
>> * Device Tree based PM domain providers.
>> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
>> index 73e938b..659997f 100644
>> --- a/include/linux/pm_domain.h
>> +++ b/include/linux/pm_domain.h
>> @@ -25,6 +25,13 @@ enum gpd_status {
>> GPD_STATE_POWER_OFF, /* PM domain is off */
>> };
>>
>> +enum gpd_on_off_state {
>> + GPD_OFF_PRE = 0, /* GPD state before power off */
>> + GPD_OFF_POST, /* GPD state after power off */
>> + GPD_ON_PRE, /* GPD state before power on */
>> + GPD_ON_POST, /* GPD state after power on */
>> +};
>> +
>> struct dev_power_governor {
>> bool (*power_down_ok)(struct dev_pm_domain *domain);
>> bool (*stop_ok)(struct device *dev);
>> @@ -148,6 +155,12 @@ extern int pm_genpd_name_poweron(const char *domain_name);
>>
>> extern struct dev_power_governor simple_qos_governor;
>> extern struct dev_power_governor pm_domain_always_on_gov;
>> +
>> +struct generic_pm_domain *pm_genpd_lookup_name(const char *domain_name);
>> +int genpd_register_notifier(struct notifier_block *nb, char *pd_name);
>> +int genpd_unregister_notifier(struct notifier_block *nb, char *pd_name);
>> +void genpd_invoke_transition_notifier(struct generic_pm_domain *genpd,
>> + enum gpd_on_off_state state);
>> #else
>>
>> static inline struct generic_pm_domain_data *dev_gpd_data(struct device *dev)
>> @@ -219,6 +232,24 @@ static inline int pm_genpd_name_poweron(const char *domain_name)
>> {
>> return -ENOSYS;
>> }
>> +static inline struct
>> +generic_pm_domain *pm_genpd_lookup_name(const char *domain_name)
>> +{
>> + return NULL;
>> +}
>> +static inline int
>> +genpd_register_notifier(struct notifier_block *nb, char *pd_name)
>> +{
>> + return 0;
>> +}
>> +static inline int
>> +genpd_unregister_notifier(struct notifier_block *nb, char *pd_name)
>> +{
>> + return 0;
>> +}
>> +static inline void
>> +genpd_invoke_transition_notifier(struct generic_pm_domain *genpd,
>> + enum gpd_on_off_state state) { }
>> #define simple_qos_governor NULL
>> #define pm_domain_always_on_gov NULL
>> #endif
>>
>
> --
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.
> --
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