[PATCH 1/3] [RFC] PM: domains: Introduce .power_pre/post_on/off callbacks

[Marek Vasut <marex@denx.de>]

Currently it is possible that a power domain power on or off would claim
the genpd lock first and clock core prepare_lock second, while another
thread could do the reverse, and this would trigger lockdep warning.

Introduce new callbacks, .power_pre/post_on() and .power_off_pre/post(), which
are triggered before the genpd_lock() and after genpd_unlock() respectively in
case the domain is powered on and off. Those are meant to let drivers claim
clock core prepare_lock via clk_*prepare() call and release the lock via
clk_*unprepare() call to always assure that the clock and genpd lock ordering
is correct.

Signed-off-by: Marek Vasut <marex@denx.de>
---
Cc: Adam Ford <aford173@gmail.com>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jacky Bai <ping.bai@nxp.com>
Cc: Kevin Hilman <khilman@kernel.org>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Marek Vasut <marex@denx.de>
Cc: Mark Brown <broonie@kernel.org>
Cc: Martin Kepplinger <martink@posteo.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Shengjiu Wang <shengjiu.wang@nxp.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: linux-clk@vger.kernel.org
Cc: linux-imx@nxp.com
Cc: linux-pm@vger.kernel.org
To: linux-arm-kernel@lists.infradead.org
---
 drivers/base/power/domain.c | 103 ++++++++++++++++++++++++++++++++----
 include/linux/pm_domain.h   |   4 ++
 2 files changed, 97 insertions(+), 10 deletions(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 6471b559230e9..df2a93d0674e4 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -494,6 +494,22 @@ void dev_pm_genpd_set_next_wakeup(struct device *dev, ktime_t next)
 }
 EXPORT_SYMBOL_GPL(dev_pm_genpd_set_next_wakeup);
 
+static int genpd_power_pre_on(struct generic_pm_domain *genpd)
+{
+	if (!genpd->power_pre_on)
+		return 0;
+
+	return genpd->power_pre_on(genpd);
+}
+
+static int genpd_power_post_on(struct generic_pm_domain *genpd)
+{
+	if (!genpd->power_post_on)
+		return 0;
+
+	return genpd->power_post_on(genpd);
+}
+
 static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
 {
 	unsigned int state_idx = genpd->state_idx;
@@ -544,6 +560,22 @@ static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
 	return ret;
 }
 
+static int genpd_power_off_pre(struct generic_pm_domain *genpd)
+{
+	if (!genpd->power_off_pre)
+		return 0;
+
+	return genpd->power_off_pre(genpd);
+}
+
+static int genpd_power_off_post(struct generic_pm_domain *genpd)
+{
+	if (!genpd->power_off_post)
+		return 0;
+
+	return genpd->power_off_post(genpd);
+}
+
 static int _genpd_power_off(struct generic_pm_domain *genpd, bool timed)
 {
 	unsigned int state_idx = genpd->state_idx;
@@ -816,12 +848,18 @@ static int genpd_dev_pm_qos_notifier(struct notifier_block *nb,
 static void genpd_power_off_work_fn(struct work_struct *work)
 {
 	struct generic_pm_domain *genpd;
+	int ret;
 
 	genpd = container_of(work, struct generic_pm_domain, power_off_work);
 
+	ret = genpd_power_off_pre(genpd);
+	if (ret)
+		return;
 	genpd_lock(genpd);
 	genpd_power_off(genpd, false, 0);
 	genpd_unlock(genpd);
+	ret = genpd_power_off_post(genpd);
+	WARN_ON_ONCE(ret);
 }
 
 /**
@@ -938,12 +976,14 @@ static int genpd_runtime_suspend(struct device *dev)
 	if (irq_safe_dev_in_sleep_domain(dev, genpd))
 		return 0;
 
+	ret = genpd_power_off_pre(genpd);
+	if (ret)
+		return ret;
 	genpd_lock(genpd);
 	gpd_data->rpm_pstate = genpd_drop_performance_state(dev);
 	genpd_power_off(genpd, true, 0);
 	genpd_unlock(genpd);
-
-	return 0;
+	return genpd_power_off_post(genpd);
 }
 
 /**
@@ -977,12 +1017,21 @@ static int genpd_runtime_resume(struct device *dev)
 	if (irq_safe_dev_in_sleep_domain(dev, genpd))
 		goto out;
 
+	ret = genpd_power_pre_on(genpd);
+	if (ret)
+		return ret;
 	genpd_lock(genpd);
 	ret = genpd_power_on(genpd, 0);
 	if (!ret)
 		genpd_restore_performance_state(dev, gpd_data->rpm_pstate);
 	genpd_unlock(genpd);
 
+	if (ret) {
+		genpd_power_post_on(genpd);
+		return ret;
+	}
+
+	ret = genpd_power_post_on(genpd);
 	if (ret)
 		return ret;
 
@@ -1017,10 +1066,13 @@ static int genpd_runtime_resume(struct device *dev)
 	genpd_stop_dev(genpd, dev);
 err_poweroff:
 	if (!pm_runtime_is_irq_safe(dev) || genpd_is_irq_safe(genpd)) {
-		genpd_lock(genpd);
-		gpd_data->rpm_pstate = genpd_drop_performance_state(dev);
-		genpd_power_off(genpd, true, 0);
-		genpd_unlock(genpd);
+		if (!genpd_power_off_pre(genpd)) {
+			genpd_lock(genpd);
+			gpd_data->rpm_pstate = genpd_drop_performance_state(dev);
+			genpd_power_off(genpd, true, 0);
+			genpd_unlock(genpd);
+			genpd_power_off_post(genpd);
+		}
 	}
 
 	return ret;
@@ -1225,12 +1277,14 @@ static int genpd_finish_suspend(struct device *dev, bool poweroff)
 		}
 	}
 
+	ret = genpd_power_off_pre(genpd);
+	if (ret)
+		return ret;
 	genpd_lock(genpd);
 	genpd->suspended_count++;
 	genpd_sync_power_off(genpd, true, 0);
 	genpd_unlock(genpd);
-
-	return 0;
+	return genpd_power_off_post(genpd);
 }
 
 /**
@@ -1267,10 +1321,16 @@ static int genpd_resume_noirq(struct device *dev)
 	if (device_wakeup_path(dev) && genpd_is_active_wakeup(genpd))
 		return pm_generic_resume_noirq(dev);
 
+	ret = genpd_power_pre_on(genpd);
+	if (ret)
+		return ret;
 	genpd_lock(genpd);
 	genpd_sync_power_on(genpd, true, 0);
 	genpd->suspended_count--;
 	genpd_unlock(genpd);
+	ret = genpd_power_post_on(genpd);
+	if (ret)
+		return ret;
 
 	if (genpd->dev_ops.stop && genpd->dev_ops.start &&
 	    !pm_runtime_status_suspended(dev)) {
@@ -1378,6 +1438,9 @@ static int genpd_restore_noirq(struct device *dev)
 	 * At this point suspended_count == 0 means we are being run for the
 	 * first time for the given domain in the present cycle.
 	 */
+	ret = genpd_power_pre_on(genpd);
+	if (ret)
+		return ret;
 	genpd_lock(genpd);
 	if (genpd->suspended_count++ == 0) {
 		/*
@@ -1390,6 +1453,9 @@ static int genpd_restore_noirq(struct device *dev)
 
 	genpd_sync_power_on(genpd, true, 0);
 	genpd_unlock(genpd);
+	ret = genpd_power_post_on(genpd);
+	if (ret)
+		return ret;
 
 	if (genpd->dev_ops.stop && genpd->dev_ops.start &&
 	    !pm_runtime_status_suspended(dev)) {
@@ -1413,6 +1479,7 @@ static int genpd_restore_noirq(struct device *dev)
 static void genpd_complete(struct device *dev)
 {
 	struct generic_pm_domain *genpd;
+	int ret;
 
 	dev_dbg(dev, "%s()\n", __func__);
 
@@ -1435,6 +1502,7 @@ static void genpd_switch_state(struct device *dev, bool suspend)
 {
 	struct generic_pm_domain *genpd;
 	bool use_lock;
+	int ret;
 
 	genpd = dev_to_genpd_safe(dev);
 	if (!genpd)
@@ -1442,8 +1510,13 @@ static void genpd_switch_state(struct device *dev, bool suspend)
 
 	use_lock = genpd_is_irq_safe(genpd);
 
-	if (use_lock)
+	if (use_lock) {
+		ret = suspend ? genpd_power_off_pre(genpd) :
+				genpd_power_pre_on(genpd);
+		if (ret)
+			return;
 		genpd_lock(genpd);
+	}
 
 	if (suspend) {
 		genpd->suspended_count++;
@@ -1453,8 +1526,12 @@ static void genpd_switch_state(struct device *dev, bool suspend)
 		genpd->suspended_count--;
 	}
 
-	if (use_lock)
+	if (use_lock) {
 		genpd_unlock(genpd);
+		ret = suspend ? genpd_power_off_post(genpd) :
+				genpd_power_post_on(genpd);
+		WARN_ON_ONCE(ret);
+	}
 }
 
 /**
@@ -2750,9 +2827,15 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
 	dev->pm_domain->sync = genpd_dev_pm_sync;
 
 	if (power_on) {
+		ret = genpd_power_pre_on(pd);
+		if (ret)
+			return ret;
 		genpd_lock(pd);
 		ret = genpd_power_on(pd, 0);
 		genpd_unlock(pd);
+		ret = genpd_power_post_on(pd);
+		if (ret)
+			return ret;
 	}
 
 	if (ret) {
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index ebc3516980907..3cf231a27cb1b 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -134,8 +134,12 @@ struct generic_pm_domain {
 	unsigned int prepared_count;	/* Suspend counter of prepared devices */
 	unsigned int performance_state;	/* Aggregated max performance state */
 	cpumask_var_t cpus;		/* A cpumask of the attached CPUs */
+	int (*power_off_pre)(struct generic_pm_domain *domain);
 	int (*power_off)(struct generic_pm_domain *domain);
+	int (*power_off_post)(struct generic_pm_domain *domain);
+	int (*power_pre_on)(struct generic_pm_domain *domain);
 	int (*power_on)(struct generic_pm_domain *domain);
+	int (*power_post_on)(struct generic_pm_domain *domain);
 	struct raw_notifier_head power_notifiers; /* Power on/off notifiers */
 	struct opp_table *opp_table;	/* OPP table of the genpd */
 	unsigned int (*opp_to_performance_state)(struct generic_pm_domain *genpd,
-- 
2.35.1