diff mbox series

[RESEND,v3,1/5] PM: domains: Allow devices attached to genpd to be managed by HW

Message ID 20231101-gdsc-hwctrl-v3-1-0740ae6b2b04@linaro.org (mailing list archive)
State Superseded
Headers show
Series PM: domains: Add control for switching back and forth to HW control | expand

Commit Message

Abel Vesa Nov. 1, 2023, 9:04 a.m. UTC 
From: Ulf Hansson <ulf.hansson@linaro.org>

Some power-domains may be capable of relying on the HW to control the power
for a device that's hooked up to it. Typically, for these kinds of
configurations the device doesn't really need to be attached to a PM domain
(genpd), from Linux point of view. However, in some cases the behaviour of
the power-domain and its device can be changed in runtime.

To allow a consumer driver to change the behaviour of the PM domain for its
device, let's provide a new function, dev_pm_genpd_set_hwmode(). Moreover,
let's add a corresponding optional genpd callback, ->set_hwmode_dev(),
which the genpd provider should implement if it can support switching
between HW controlled mode and SW controlled mode. Similarly, add the
dev_pm_genpd_get_hwmode() to allow consumers to read the current mode and
its corresponding optional genpd callback, ->get_hwmode_dev(), which the
genpd provider can also implement for reading back the mode from the
hardware.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
---
 drivers/base/power/domain.c | 69 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/pm_domain.h   | 17 +++++++++++
 2 files changed, 86 insertions(+)

Comments

Dmitry Baryshkov Nov. 1, 2023, 9:26 p.m. UTC | #1 
On Wed, 1 Nov 2023 at 11:08, Abel Vesa <abel.vesa@linaro.org> wrote:
>
> From: Ulf Hansson <ulf.hansson@linaro.org>
>
> Some power-domains may be capable of relying on the HW to control the power
> for a device that's hooked up to it. Typically, for these kinds of
> configurations the device doesn't really need to be attached to a PM domain
> (genpd), from Linux point of view. However, in some cases the behaviour of
> the power-domain and its device can be changed in runtime.
>
> To allow a consumer driver to change the behaviour of the PM domain for its
> device, let's provide a new function, dev_pm_genpd_set_hwmode(). Moreover,
> let's add a corresponding optional genpd callback, ->set_hwmode_dev(),
> which the genpd provider should implement if it can support switching
> between HW controlled mode and SW controlled mode. Similarly, add the
> dev_pm_genpd_get_hwmode() to allow consumers to read the current mode and
> its corresponding optional genpd callback, ->get_hwmode_dev(), which the
> genpd provider can also implement for reading back the mode from the
> hardware.
>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> Signed-off-by: Abel Vesa <abel.vesa@linaro.org>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Bjorn Andersson Nov. 3, 2023, 7:46 p.m. UTC | #2 
On Wed, Nov 01, 2023 at 11:04:07AM +0200, Abel Vesa wrote:
> From: Ulf Hansson <ulf.hansson@linaro.org>
> 
> Some power-domains may be capable of relying on the HW to control the power
> for a device that's hooked up to it. Typically, for these kinds of
> configurations the device doesn't really need to be attached to a PM domain
> (genpd), from Linux point of view.

Per patch 5, this description isn't correct.

Linux enables the power-domain, which in turn enables parent domains
etc. Once the firmware is booted the hardware-control mechanism is
engaged, but until then, and in order to keep the supplies to the domain
voted for, Linux needs a proper genpd.

Regards,
Bjorn

> However, in some cases the behaviour of
> the power-domain and its device can be changed in runtime.
> 
> To allow a consumer driver to change the behaviour of the PM domain for its
> device, let's provide a new function, dev_pm_genpd_set_hwmode(). Moreover,
> let's add a corresponding optional genpd callback, ->set_hwmode_dev(),
> which the genpd provider should implement if it can support switching
> between HW controlled mode and SW controlled mode. Similarly, add the
> dev_pm_genpd_get_hwmode() to allow consumers to read the current mode and
> its corresponding optional genpd callback, ->get_hwmode_dev(), which the
> genpd provider can also implement for reading back the mode from the
> hardware.
> 
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
> ---
>  drivers/base/power/domain.c | 69 +++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pm_domain.h   | 17 +++++++++++
>  2 files changed, 86 insertions(+)
> 
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index da1777e39eaa..3fb1a234c7f2 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -550,6 +550,75 @@ void dev_pm_genpd_synced_poweroff(struct device *dev)
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_genpd_synced_poweroff);
>  
> +/**
> + * dev_pm_genpd_set_hwmode - Set the HW mode for the device and its PM domain.
> + *
> + * @dev: Device for which the HW-mode should be changed.
> + * @enable: Value to set or unset the HW-mode.
> + *
> + * Some PM domains can rely on HW signals to control the power for a device. To
> + * allow a consumer driver to switch the behaviour for its device in runtime,
> + * which may be beneficial from a latency or energy point of view, this function
> + * may be called.
> + *
> + * It is assumed that the users guarantee that the genpd wouldn't be detached
> + * while this routine is getting called.
> + *
> + * Returns 0 on success and negative error values on failures.
> + */
> +int dev_pm_genpd_set_hwmode(struct device *dev, bool enable)
> +{
> +	struct generic_pm_domain *genpd;
> +	int ret = 0;
> +
> +	genpd = dev_to_genpd_safe(dev);
> +	if (!genpd)
> +		return -ENODEV;
> +
> +	if (!genpd->set_hwmode_dev)
> +		return -EOPNOTSUPP;
> +
> +	genpd_lock(genpd);
> +
> +	if (dev_gpd_data(dev)->hw_mode == enable)
> +		goto out;
> +
> +	ret = genpd->set_hwmode_dev(genpd, dev, enable);
> +	if (!ret)
> +		dev_gpd_data(dev)->hw_mode = enable;
> +
> +out:
> +	genpd_unlock(genpd);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_genpd_set_hwmode);
> +
> +/**
> + * dev_pm_genpd_get_hwmode - Get the HW mode setting for the device.
> + *
> + * @dev: Device for which the current HW-mode setting should be fetched.
> + *
> + * This helper function allows consumer drivers to fetch the current HW mode
> + * setting of its the device.
> + *
> + * It is assumed that the users guarantee that the genpd wouldn't be detached
> + * while this routine is getting called.
> + */
> +bool dev_pm_genpd_get_hwmode(struct device *dev)
> +{
> +	struct generic_pm_domain *genpd;
> +
> +	genpd = dev_to_genpd_safe(dev);
> +	if (!genpd)
> +		return false;
> +
> +	if (genpd->get_hwmode_dev)
> +		return genpd->get_hwmode_dev(genpd, dev);
> +
> +	return dev_gpd_data(dev)->hw_mode;
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_genpd_get_hwmode);
> +
>  static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
>  {
>  	unsigned int state_idx = genpd->state_idx;
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 34663d0d5c55..0e7d177fdc3e 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -151,6 +151,10 @@ struct generic_pm_domain {
>  	int (*set_performance_state)(struct generic_pm_domain *genpd,
>  				     unsigned int state);
>  	struct gpd_dev_ops dev_ops;
> +	int (*set_hwmode_dev)(struct generic_pm_domain *domain,
> +			      struct device *dev, bool enable);
> +	bool (*get_hwmode_dev)(struct generic_pm_domain *domain,
> +			      struct device *dev);
>  	int (*attach_dev)(struct generic_pm_domain *domain,
>  			  struct device *dev);
>  	void (*detach_dev)(struct generic_pm_domain *domain,
> @@ -213,6 +217,7 @@ struct generic_pm_domain_data {
>  	unsigned int performance_state;
>  	unsigned int default_pstate;
>  	unsigned int rpm_pstate;
> +	bool hw_mode;
>  	void *data;
>  };
>  
> @@ -242,6 +247,8 @@ int dev_pm_genpd_remove_notifier(struct device *dev);
>  void dev_pm_genpd_set_next_wakeup(struct device *dev, ktime_t next);
>  ktime_t dev_pm_genpd_get_next_hrtimer(struct device *dev);
>  void dev_pm_genpd_synced_poweroff(struct device *dev);
> +int dev_pm_genpd_set_hwmode(struct device *dev, bool enable);
> +bool dev_pm_genpd_get_hwmode(struct device *dev);
>  
>  extern struct dev_power_governor simple_qos_governor;
>  extern struct dev_power_governor pm_domain_always_on_gov;
> @@ -310,6 +317,16 @@ static inline ktime_t dev_pm_genpd_get_next_hrtimer(struct device *dev)
>  static inline void dev_pm_genpd_synced_poweroff(struct device *dev)
>  { }
>  
> +static inline int dev_pm_genpd_set_hwmode(struct device *dev, bool enable)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static inline bool dev_pm_genpd_get_hwmode(struct device *dev)
> +{
> +	return false;
> +}
> +
>  #define simple_qos_governor		(*(struct dev_power_governor *)(NULL))
>  #define pm_domain_always_on_gov		(*(struct dev_power_governor *)(NULL))
>  #endif
> 
> -- 
> 2.34.1
>
diff mbox series

Patch

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index da1777e39eaa..3fb1a234c7f2 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -550,6 +550,75 @@  void dev_pm_genpd_synced_poweroff(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(dev_pm_genpd_synced_poweroff);
 
+/**
+ * dev_pm_genpd_set_hwmode - Set the HW mode for the device and its PM domain.
+ *
+ * @dev: Device for which the HW-mode should be changed.
+ * @enable: Value to set or unset the HW-mode.
+ *
+ * Some PM domains can rely on HW signals to control the power for a device. To
+ * allow a consumer driver to switch the behaviour for its device in runtime,
+ * which may be beneficial from a latency or energy point of view, this function
+ * may be called.
+ *
+ * It is assumed that the users guarantee that the genpd wouldn't be detached
+ * while this routine is getting called.
+ *
+ * Returns 0 on success and negative error values on failures.
+ */
+int dev_pm_genpd_set_hwmode(struct device *dev, bool enable)
+{
+	struct generic_pm_domain *genpd;
+	int ret = 0;
+
+	genpd = dev_to_genpd_safe(dev);
+	if (!genpd)
+		return -ENODEV;
+
+	if (!genpd->set_hwmode_dev)
+		return -EOPNOTSUPP;
+
+	genpd_lock(genpd);
+
+	if (dev_gpd_data(dev)->hw_mode == enable)
+		goto out;
+
+	ret = genpd->set_hwmode_dev(genpd, dev, enable);
+	if (!ret)
+		dev_gpd_data(dev)->hw_mode = enable;
+
+out:
+	genpd_unlock(genpd);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_genpd_set_hwmode);
+
+/**
+ * dev_pm_genpd_get_hwmode - Get the HW mode setting for the device.
+ *
+ * @dev: Device for which the current HW-mode setting should be fetched.
+ *
+ * This helper function allows consumer drivers to fetch the current HW mode
+ * setting of its the device.
+ *
+ * It is assumed that the users guarantee that the genpd wouldn't be detached
+ * while this routine is getting called.
+ */
+bool dev_pm_genpd_get_hwmode(struct device *dev)
+{
+	struct generic_pm_domain *genpd;
+
+	genpd = dev_to_genpd_safe(dev);
+	if (!genpd)
+		return false;
+
+	if (genpd->get_hwmode_dev)
+		return genpd->get_hwmode_dev(genpd, dev);
+
+	return dev_gpd_data(dev)->hw_mode;
+}
+EXPORT_SYMBOL_GPL(dev_pm_genpd_get_hwmode);
+
 static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
 {
 	unsigned int state_idx = genpd->state_idx;
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 34663d0d5c55..0e7d177fdc3e 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -151,6 +151,10 @@  struct generic_pm_domain {
 	int (*set_performance_state)(struct generic_pm_domain *genpd,
 				     unsigned int state);
 	struct gpd_dev_ops dev_ops;
+	int (*set_hwmode_dev)(struct generic_pm_domain *domain,
+			      struct device *dev, bool enable);
+	bool (*get_hwmode_dev)(struct generic_pm_domain *domain,
+			      struct device *dev);
 	int (*attach_dev)(struct generic_pm_domain *domain,
 			  struct device *dev);
 	void (*detach_dev)(struct generic_pm_domain *domain,
@@ -213,6 +217,7 @@  struct generic_pm_domain_data {
 	unsigned int performance_state;
 	unsigned int default_pstate;
 	unsigned int rpm_pstate;
+	bool hw_mode;
 	void *data;
 };
 
@@ -242,6 +247,8 @@  int dev_pm_genpd_remove_notifier(struct device *dev);
 void dev_pm_genpd_set_next_wakeup(struct device *dev, ktime_t next);
 ktime_t dev_pm_genpd_get_next_hrtimer(struct device *dev);
 void dev_pm_genpd_synced_poweroff(struct device *dev);
+int dev_pm_genpd_set_hwmode(struct device *dev, bool enable);
+bool dev_pm_genpd_get_hwmode(struct device *dev);
 
 extern struct dev_power_governor simple_qos_governor;
 extern struct dev_power_governor pm_domain_always_on_gov;
@@ -310,6 +317,16 @@  static inline ktime_t dev_pm_genpd_get_next_hrtimer(struct device *dev)
 static inline void dev_pm_genpd_synced_poweroff(struct device *dev)
 { }
 
+static inline int dev_pm_genpd_set_hwmode(struct device *dev, bool enable)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline bool dev_pm_genpd_get_hwmode(struct device *dev)
+{
+	return false;
+}
+
 #define simple_qos_governor		(*(struct dev_power_governor *)(NULL))
 #define pm_domain_always_on_gov		(*(struct dev_power_governor *)(NULL))
 #endif