[PATCH V3 6/6] can: flexcan: add LPSR mode support

[Joakim Zhang <qiangqing.zhang@xxxxxxx>]

For i.MX7D LPSR mode, the controller will lost power and got the
configuration state lost after system resume back. (coming i.MX8QM/QXP
will also completely power off the domain, the controller state will be
lost and needs restore).
So we need to set pinctrl state again and re-start chip to do
re-configuration after resume.

For wakeup case, it should not set pinctrl to sleep state by
pinctrl_pm_select_sleep_state.
For interface is not up before suspend case, we don't need
re-configure as it will be configured by user later by interface up.

Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>
------
ChangeLog:
	V1->V2: *no change.

	V2->V3: *add error handling for pinctrl_pm_xx_xx_state()
		 function.
---
 drivers/net/can/flexcan.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index c5e4b6928dee..3570ebe3b8f2 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -26,6 +26,7 @@
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/regmap.h>
 
 #define DRV_NAME			"flexcan"
@@ -1700,7 +1701,7 @@ static int __maybe_unused flexcan_suspend(struct device *device)
 {
 	struct net_device *dev = dev_get_drvdata(device);
 	struct flexcan_priv *priv = netdev_priv(dev);
-	int err = 0;
+	int err;
 
 	if (netif_running(dev)) {
 		/* if wakeup is enabled, enter stop mode
@@ -1712,25 +1713,31 @@ static int __maybe_unused flexcan_suspend(struct device *device)
 			if (err)
 				return err;
 		} else {
-			err = flexcan_chip_disable(priv);
+			err = flexcan_chip_stop(dev);
 			if (err)
 				return err;
 
 			err = pm_runtime_force_suspend(device);
+			if (err)
+				return err;
+
+			err = pinctrl_pm_select_sleep_state(device);
+			if (err)
+				return err;
 		}
 		netif_stop_queue(dev);
 		netif_device_detach(dev);
 	}
 	priv->can.state = CAN_STATE_SLEEPING;
 
-	return err;
+	return 0;
 }
 
 static int __maybe_unused flexcan_resume(struct device *device)
 {
 	struct net_device *dev = dev_get_drvdata(device);
 	struct flexcan_priv *priv = netdev_priv(dev);
-	int err = 0;
+	int err;
 
 	priv->can.state = CAN_STATE_ERROR_ACTIVE;
 	if (netif_running(dev)) {
@@ -1742,15 +1749,21 @@ static int __maybe_unused flexcan_resume(struct device *device)
 			if (err)
 				return err;
 		} else {
+			err = pinctrl_pm_select_default_state(device);
+			if (err)
+				return err;
+
 			err = pm_runtime_force_resume(device);
 			if (err)
 				return err;
 
-			err = flexcan_chip_enable(priv);
+			err = flexcan_chip_start(dev);
+			if (err)
+				return err;
 		}
 	}
 
-	return err;
+	return 0;
 }
 
 static int __maybe_unused flexcan_runtime_suspend(struct device *device)
-- 
2.17.1