[PATCH V2] can: flexcan: implement can Runtime PM

[Joakim Zhang <qiangqing.zhang@nxp.com>]

From: Aisheng Dong <aisheng.dong@nxp.com>

Flexcan will be disabled during suspend if no wakeup function required and
enabled after resume accordingly. During this period, we could explicitly
disable clocks.

Implement Runtime PM which will:
1) Keep device in suspend state (clocks disabled) if it's not openned.
2) Make Power Domain framework be able to shutdown the corresponding power
   domain of this device.

Signed-off-by: Aisheng Dong <aisheng.dong@nxp.com>
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
---
ChangeLog:
V1->V2:
	*rebased on patch "can: flexcan: add self wakeup support".
	*add check when to do flexcan_clks_disable/enable() during
	 Runtime PM.
---
 drivers/net/can/flexcan.c | 119 ++++++++++++++++++++++++--------------
 1 file changed, 77 insertions(+), 42 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index d12b2f7d2834..130a2cb04827 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -24,6 +24,7 @@
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
 #include <linux/regmap.h>
 
@@ -277,6 +278,7 @@ struct flexcan_priv {
 	u32 reg_imask1_default;
 	u32 reg_imask2_default;
 
+	struct device *dev;
 	struct clk *clk_ipg;
 	struct clk *clk_per;
 	const struct flexcan_devtype_data *devtype_data;
@@ -444,6 +446,27 @@ static inline void flexcan_error_irq_disable(const struct flexcan_priv *priv)
 	priv->write(reg_ctrl, &regs->ctrl);
 }
 
+static int flexcan_clks_enable(const struct flexcan_priv *priv)
+{
+	int err;
+
+	err = clk_prepare_enable(priv->clk_ipg);
+	if (err)
+		return err;
+
+	err = clk_prepare_enable(priv->clk_per);
+	if (err)
+		clk_disable_unprepare(priv->clk_ipg);
+
+	return err;
+}
+
+static void flexcan_clks_disable(const struct flexcan_priv *priv)
+{
+	clk_disable_unprepare(priv->clk_ipg);
+	clk_disable_unprepare(priv->clk_per);
+}
+
 static inline int flexcan_transceiver_enable(const struct flexcan_priv *priv)
 {
 	if (!priv->reg_xceiver)
@@ -570,19 +593,11 @@ static int flexcan_get_berr_counter(const struct net_device *dev,
 	const struct flexcan_priv *priv = netdev_priv(dev);
 	int err;
 
-	err = clk_prepare_enable(priv->clk_ipg);
-	if (err)
-		return err;
-
-	err = clk_prepare_enable(priv->clk_per);
-	if (err)
-		goto out_disable_ipg;
+	pm_runtime_get_sync(priv->dev);
 
 	err = __flexcan_get_berr_counter(dev, bec);
 
-	clk_disable_unprepare(priv->clk_per);
- out_disable_ipg:
-	clk_disable_unprepare(priv->clk_ipg);
+	pm_runtime_put(priv->dev);
 
 	return err;
 }
@@ -1215,17 +1230,13 @@ static int flexcan_open(struct net_device *dev)
 	struct flexcan_priv *priv = netdev_priv(dev);
 	int err;
 
-	err = clk_prepare_enable(priv->clk_ipg);
+	err = pm_runtime_get_sync(priv->dev);
 	if (err)
 		return err;
 
-	err = clk_prepare_enable(priv->clk_per);
-	if (err)
-		goto out_disable_ipg;
-
 	err = open_candev(dev);
 	if (err)
-		goto out_disable_per;
+		goto out_pm_runtime;
 
 	err = request_irq(dev->irq, flexcan_irq, IRQF_SHARED, dev->name, dev);
 	if (err)
@@ -1288,10 +1299,8 @@ static int flexcan_open(struct net_device *dev)
 	free_irq(dev->irq, dev);
  out_close:
 	close_candev(dev);
- out_disable_per:
-	clk_disable_unprepare(priv->clk_per);
- out_disable_ipg:
-	clk_disable_unprepare(priv->clk_ipg);
+ out_pm_runtime:
+	pm_runtime_put(priv->dev);
 
 	return err;
 }
@@ -1306,11 +1315,11 @@ static int flexcan_close(struct net_device *dev)
 
 	can_rx_offload_del(&priv->offload);
 	free_irq(dev->irq, dev);
-	clk_disable_unprepare(priv->clk_per);
-	clk_disable_unprepare(priv->clk_ipg);
 
 	close_candev(dev);
 
+	pm_runtime_put(priv->dev);
+
 	can_led_event(dev, CAN_LED_EVENT_STOP);
 
 	return 0;
@@ -1349,18 +1358,10 @@ static int register_flexcandev(struct net_device *dev)
 	struct flexcan_regs __iomem *regs = priv->regs;
 	u32 reg, err;
 
-	err = clk_prepare_enable(priv->clk_ipg);
-	if (err)
-		return err;
-
-	err = clk_prepare_enable(priv->clk_per);
-	if (err)
-		goto out_disable_ipg;
-
 	/* select "bus clock", chip must be disabled */
 	err = flexcan_chip_disable(priv);
 	if (err)
-		goto out_disable_per;
+		return err;
 	reg = priv->read(&regs->ctrl);
 	reg |= FLEXCAN_CTRL_CLK_SRC;
 	priv->write(reg, &regs->ctrl);
@@ -1389,13 +1390,8 @@ static int register_flexcandev(struct net_device *dev)
 
 	err = register_candev(dev);
 
-	/* disable core and turn off clocks */
  out_chip_disable:
 	flexcan_chip_disable(priv);
- out_disable_per:
-	clk_disable_unprepare(priv->clk_per);
- out_disable_ipg:
-	clk_disable_unprepare(priv->clk_ipg);
 
 	return err;
 }
@@ -1556,6 +1552,7 @@ static int flexcan_probe(struct platform_device *pdev)
 		priv->write = flexcan_write_le;
 	}
 
+	priv->dev = &pdev->dev;
 	priv->can.clock.freq = clock_freq;
 	priv->can.bittiming_const = &flexcan_bittiming_const;
 	priv->can.do_set_mode = flexcan_set_mode;
@@ -1569,14 +1566,23 @@ static int flexcan_probe(struct platform_device *pdev)
 	priv->devtype_data = devtype_data;
 	priv->reg_xceiver = reg_xceiver;
 
+	pm_runtime_enable(&pdev->dev);
+	err = pm_runtime_get_sync(&pdev->dev);
+	if (err < 0) {
+		dev_err(&pdev->dev, "pm_runtime_get failed(%d)\n", err);
+		goto failed_rpm_disable;
+	}
+
 	err = register_flexcandev(dev);
 	if (err) {
 		dev_err(&pdev->dev, "registering netdev failed\n");
-		goto failed_register;
+		goto failed_rpm_put;
 	}
 
 	devm_can_led_init(dev);
 
+	pm_runtime_put(&pdev->dev);
+
 	if (priv->devtype_data->quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE) {
 		err = flexcan_setup_stop_mode(pdev);
 		if (err)
@@ -1588,8 +1594,11 @@ static int flexcan_probe(struct platform_device *pdev)
 
 	return 0;
 
- failed_register:
+ failed_rpm_put:
+	pm_runtime_put(&pdev->dev);
 	free_candev(dev);
+ failed_rpm_disable:
+	pm_runtime_disable(&pdev->dev);
 	return err;
 }
 
@@ -1598,6 +1607,7 @@ static int flexcan_remove(struct platform_device *pdev)
 	struct net_device *dev = platform_get_drvdata(pdev);
 
 	unregister_flexcandev(dev);
+	pm_runtime_disable(&pdev->dev);
 	free_candev(dev);
 
 	return 0;
@@ -1607,7 +1617,7 @@ 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;
+	int err = 0;
 
 	if (netif_running(dev)) {
 		/* if wakeup is enabled, enter stop mode
@@ -1620,20 +1630,21 @@ static int __maybe_unused flexcan_suspend(struct device *device)
 			err = flexcan_chip_disable(priv);
 			if (err)
 				return err;
+			err = pm_runtime_force_suspend(device);
 		}
 		netif_stop_queue(dev);
 		netif_device_detach(dev);
 	}
 	priv->can.state = CAN_STATE_SLEEPING;
 
-	return 0;
+	return err;
 }
 
 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;
+	int err = 0;
 
 	priv->can.state = CAN_STATE_ERROR_ACTIVE;
 	if (netif_running(dev)) {
@@ -1642,11 +1653,34 @@ static int __maybe_unused flexcan_resume(struct device *device)
 		if (device_may_wakeup(device)) {
 			disable_irq_wake(dev->irq);
 		} else {
-			err = flexcan_chip_enable(priv);
+			err = pm_runtime_force_resume(device);
 			if (err)
 				return err;
+			err = flexcan_chip_enable(priv);
 		}
 	}
+	return err;
+}
+
+static int __maybe_unused flexcan_runtime_suspend(struct device *device)
+{
+	struct net_device *dev = dev_get_drvdata(device);
+	struct flexcan_priv *priv = netdev_priv(dev);
+
+	if (netif_running(dev))
+		flexcan_clks_disable(priv);
+
+	return 0;
+}
+
+static int __maybe_unused flexcan_runtime_resume(struct device *device)
+{
+	struct net_device *dev = dev_get_drvdata(device);
+	struct flexcan_priv *priv = netdev_priv(dev);
+
+	if (!netif_running(dev))
+		flexcan_clks_enable(priv);
+
 	return 0;
 }
 
@@ -1676,6 +1710,7 @@ static int __maybe_unused flexcan_noirq_resume(struct device *device)
 
 static const struct dev_pm_ops flexcan_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(flexcan_suspend, flexcan_resume)
+	SET_RUNTIME_PM_OPS(flexcan_runtime_suspend, flexcan_runtime_resume, NULL)
 	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(flexcan_noirq_suspend, flexcan_noirq_resume)
 };
 
-- 
2.17.1