Date:   Fri, 19 Oct 2018 09:45:44 +0000
From:   Joakim Zhang <qiangqing.zhang@....com>
To:     "wg@...ndegger.com" <wg@...ndegger.com>,
        "mkl@...gutronix.de" <mkl@...gutronix.de>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>,
        "A.s. Dong" <aisheng.dong@....com>,
        Joakim Zhang <qiangqing.zhang@....com>
Subject: [PATCH] can: flexcan: Implement CAN Runtime PM

From: Dong Aisheng <aisheng.dong@....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: Dong Aisheng <aisheng.dong@....com>
Signed-off-by: Joakim Zhang <qiangqing.zhang@....com>
---
 drivers/net/can/flexcan.c | 125 +++++++++++++++++++++++++-------------
 1 file changed, 82 insertions(+), 43 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 8e972ef08637..3813f6708201 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -23,6 +23,7 @@
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
 
 #define DRV_NAME			"flexcan"
@@ -266,6 +267,7 @@ 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;
@@ -369,6 +371,27 @@ 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)
@@ -495,19 +518,11 @@ 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;
 }
@@ -1096,17 +1111,13 @@ 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)
@@ -1128,10 +1139,8 @@ 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;
 }
@@ -1145,11 +1154,11 @@ static int flexcan_close(struct net_device *dev)
 	flexcan_chip_stop(dev);
 
 	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;
@@ -1188,18 +1197,10 @@ 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);
@@ -1228,13 +1229,8 @@ 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;
 }
@@ -1342,6 +1338,7 @@ 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;
@@ -1388,22 +1385,35 @@ static int flexcan_probe(struct platform_device *pdev)
 	if (err)
 		goto failed_offload;
 
+	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);
+
 	dev_info(&pdev->dev, "device registered (reg_base=%p, irq=%d)\n",
 		 priv->regs, dev->irq);
 
 	return 0;
 
+ failed_rpm_put:
+	pm_runtime_put(&pdev->dev);
+ failed_rpm_disable:
+	pm_runtime_disable(&pdev->dev);
  failed_offload:
- failed_register:
 	free_candev(dev);
+
 	return err;
 }
 
@@ -1413,6 +1423,7 @@ static int flexcan_remove(struct platform_device *pdev)
 	struct flexcan_priv *priv = netdev_priv(dev);
 
 	unregister_flexcandev(dev);
+	pm_runtime_disable(&pdev->dev);
 	can_rx_offload_del(&priv->offload);
 	free_candev(dev);
 
@@ -1423,38 +1434,66 @@ 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)) {
 		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)) {
 		netif_device_attach(dev);
 		netif_start_queue(dev);
-		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);
+
+	flexcan_clks_disable(priv);
+
 	return 0;
 }
 
-static SIMPLE_DEV_PM_OPS(flexcan_pm_ops, flexcan_suspend, flexcan_resume);
+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);
+
+	flexcan_clks_enable(priv);
+
+	return 0;
+}
+
+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)
+};
 
 static struct platform_driver flexcan_driver = {
 	.driver = {
-- 
2.17.1

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