PM / Domains: Introduce "always on" device flag

This is a backport of mainline commit
1e78a0c7fc92aee076965d516cf54475c39e9894.

The TMU device on the Mackerel board belongs to the A4R power domain
and loses power when the domain is turned off.  Unfortunately, the
TMU driver is not prepared to cope with such situations and crashes
the system when that happens.  To work around this problem introduce
a new helper function, pm_genpd_dev_always_on(), allowing a device
driver to mark its device as "always on" in case it belongs to a PM
domain, which will make the generic PM domains core code avoid
powering off the domain containing the device, both at run time and
during system suspend.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Tested-by: Simon Horman <horms@verge.net.au>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 30 insertions, 6 deletions

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 5771275f1be4..58c8b4def2f7 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -366,7 +366,7 @@ static int pm_genpd_poweroff(struct generic_pm_domain *genpd)
 	not_suspended = 0;
 	list_for_each_entry(pdd, &genpd->dev_list, list_node)
 		if (pdd->dev->driver && (!pm_runtime_suspended(pdd->dev)
-		    || pdd->dev->power.irq_safe))
+		    || pdd->dev->power.irq_safe || to_gpd_data(pdd)->always_on))
 			not_suspended++;
 
 	if (not_suspended > genpd->in_progress)
@@ -503,6 +503,9 @@ static int pm_genpd_runtime_suspend(struct device *dev)
 
 	might_sleep_if(!genpd->dev_irq_safe);
 
+	if (dev_gpd_data(dev)->always_on)
+		return -EBUSY;
+
 	stop_ok = genpd->gov ? genpd->gov->stop_ok : NULL;
 	if (stop_ok && !stop_ok(dev))
 		return -EBUSY;
@@ -847,7 +850,8 @@ static int pm_genpd_suspend_noirq(struct device *dev)
 	if (ret)
 		return ret;
 
-	if (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev))
+	if (dev_gpd_data(dev)->always_on
+	    || (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev)))
 		return 0;
 
 	genpd_stop_dev(genpd, dev);
@@ -882,7 +886,7 @@ static int pm_genpd_resume_noirq(struct device *dev)
 	if (IS_ERR(genpd))
 		return -EINVAL;
 
-	if (genpd->suspend_power_off
+	if (genpd->suspend_power_off || dev_gpd_data(dev)->always_on
 	    || (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev)))
 		return 0;
 
@@ -960,7 +964,7 @@ static int pm_genpd_freeze_noirq(struct device *dev)
 	if (IS_ERR(genpd))
 		return -EINVAL;
 
-	if (genpd->suspend_power_off)
+	if (genpd->suspend_power_off || dev_gpd_data(dev)->always_on)
 		return 0;
 
 	ret = genpd_freeze_late(genpd, dev);
@@ -991,7 +995,7 @@ static int pm_genpd_thaw_noirq(struct device *dev)
 	if (IS_ERR(genpd))
 		return -EINVAL;
 
-	if (genpd->suspend_power_off)
+	if (genpd->suspend_power_off || dev_gpd_data(dev)->always_on)
 		return 0;
 
 	genpd_start_dev(genpd, dev);
@@ -1064,7 +1068,7 @@ static int pm_genpd_restore_noirq(struct device *dev)
 		}
 	}
 
-	if (genpd->suspend_power_off)
+	if (genpd->suspend_power_off || dev_gpd_data(dev)->always_on)
 		return 0;
 
 	pm_genpd_poweron(genpd);
@@ -1230,6 +1234,26 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
 }
 
 /**
+ * pm_genpd_dev_always_on - Set/unset the "always on" flag for a given device.
+ * @dev: Device to set/unset the flag for.
+ * @val: The new value of the device's "always on" flag.
+ */
+void pm_genpd_dev_always_on(struct device *dev, bool val)
+{
+	struct pm_subsys_data *psd;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->power.lock, flags);
+
+	psd = dev_to_psd(dev);
+	if (psd && psd->domain_data)
+		to_gpd_data(psd->domain_data)->always_on = val;
+
+	spin_unlock_irqrestore(&dev->power.lock, flags);
+}
+EXPORT_SYMBOL_GPL(pm_genpd_dev_always_on);
+
+/**
  * pm_genpd_add_subdomain - Add a subdomain to an I/O PM domain.
  * @genpd: Master PM domain to add the subdomain to.
  * @subdomain: Subdomain to be added.