Message-ID: <DB7PR04MB46184D92EC50A9CADB84969EE6C10@DB7PR04MB4618.eurprd04.prod.outlook.com>
Date:   Mon, 12 Nov 2018 01:47:31 +0000
From:   Joakim Zhang <qiangqing.zhang@....com>
To:     Marc Kleine-Budde <mkl@...gutronix.de>,
        "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>
CC:     "wg@...ndegger.com" <wg@...ndegger.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "devicetree@...r.kernel.org" <devicetree@...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>
Subject: RE: [PATCH V2 1/2] can: flexcan: Add self wakeup support


> -----Original Message-----
> From: Marc Kleine-Budde <mkl@...gutronix.de>
> Sent: 2018年10月30日 21:45
> To: Joakim Zhang <qiangqing.zhang@....com>; linux-can@...r.kernel.org
> Cc: wg@...ndegger.com; robh+dt@...nel.org; mark.rutland@....com;
> devicetree@...r.kernel.org; linux-kernel@...r.kernel.org; dl-linux-imx
> <linux-imx@....com>; A.s. Dong <aisheng.dong@....com>
> Subject: Re: [PATCH V2 1/2] can: flexcan: Add self wakeup support
> 
> On 10/26/2018 11:00 AM, Joakim Zhang wrote:
> > From: Dong Aisheng <aisheng.dong@....com>
> >
> > If wakeup is enabled, enter stop mode, else enter disabled mode.
> > Self wake can only work on stop mode.
> >
> > Starting from IMX6, the flexcan stop mode control bits is SoC
> > specific, move it out of IP driver and parse it from devicetree.
> >
> > Signed-off-by: Dong Aisheng <aisheng.dong@....com>
> > Signed-off-by: Joakim Zhang <qiangqing.zhang@....com>
> > ---
> >  drivers/net/can/flexcan.c | 141
> > +++++++++++++++++++++++++++++++++++---
> >  1 file changed, 132 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
> > index 3813f6708201..d4708ba28c44 100644
> > --- a/drivers/net/can/flexcan.c
> > +++ b/drivers/net/can/flexcan.c
> > @@ -19,12 +19,17 @@
> >  #include <linux/delay.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/io.h>
> > +#include <linux/kernel.h>
> > +#include <linux/list.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/mfd/syscon/imx6q-iomuxc-gpr.h>
> >  #include <linux/module.h>
> >  #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>
> >
> >  #define DRV_NAME			"flexcan"
> >
> > @@ -132,7 +137,8 @@
> >  	(FLEXCAN_ESR_ERR_BUS | FLEXCAN_ESR_ERR_STATE)  #define
> > FLEXCAN_ESR_ALL_INT \
> >  	(FLEXCAN_ESR_TWRN_INT | FLEXCAN_ESR_RWRN_INT | \
> > -	 FLEXCAN_ESR_BOFF_INT | FLEXCAN_ESR_ERR_INT)
> > +	 FLEXCAN_ESR_BOFF_INT | FLEXCAN_ESR_ERR_INT | \
> > +	 FLEXCAN_ESR_WAK_INT)
> >
> >  /* FLEXCAN interrupt flag register (IFLAG) bits */
> >  /* Errata ERR005829 step7: Reserve first valid MB */ @@ -255,6
> > +261,14 @@ struct flexcan_devtype_data {
> >  	u32 quirks;		/* quirks needed for different IP cores */
> >  };
> >
> > +struct flexcan_stop_mode {
> > +	struct regmap *gpr;
> > +	u8 req_gpr;
> > +	u8 req_bit;
> > +	u8 ack_gpr;
> > +	u8 ack_bit;
> > +};
> > +
> >  struct flexcan_priv {
> >  	struct can_priv can;
> >  	struct can_rx_offload offload;
> > @@ -272,6 +286,7 @@ struct flexcan_priv {
> >  	struct clk *clk_per;
> >  	const struct flexcan_devtype_data *devtype_data;
> >  	struct regulator *reg_xceiver;
> > +	struct flexcan_stop_mode stm;
> >
> >  	/* Read and Write APIs */
> >  	u32 (*read)(void __iomem *addr);
> > @@ -392,6 +407,22 @@ static void flexcan_clks_disable(const struct
> flexcan_priv *priv)
> >  	clk_disable_unprepare(priv->clk_per);
> >  }
> >
> > +static inline void flexcan_enter_stop_mode(struct flexcan_priv *priv)
> > +{
> > +	/* enable stop request */
> > +	if (priv->devtype_data->quirks & FLEXCAN_QUIRK_USE_OFF_TIMESTAMP)
> 
> Why do you check the quirk here? This should only be called if the device is
> wakeup capable.

Yes, you are right. I have moved out this check.

> > +		regmap_update_bits(priv->stm.gpr, priv->stm.req_gpr,
> > +			1 << priv->stm.req_bit, 1 << priv->stm.req_bit);
> 
> Please align with the opening bracket of "regmap_update_bits(".

Okay.

> > +}
> > +
> > +static inline void flexcan_exit_stop_mode(struct flexcan_priv *priv)
> > +{
> > +	/* remove stop request */
> > +	if (priv->devtype_data->quirks & FLEXCAN_QUIRK_USE_OFF_TIMESTAMP)
> 
> same here
Have done.

> > +		regmap_update_bits(priv->stm.gpr, priv->stm.req_gpr,
> > +			1 << priv->stm.req_bit, 0);
> 
> same here
Have done.

> > +}
> > +
> >  static inline int flexcan_transceiver_enable(const struct
> > flexcan_priv *priv)  {
> >  	if (!priv->reg_xceiver)
> > @@ -955,6 +986,10 @@ static int flexcan_chip_start(struct net_device
> *dev)
> >  		reg_mcr |= FLEXCAN_MCR_FEN |
> >  			FLEXCAN_MCR_MAXMB(priv->tx_mb_idx);
> >  	}
> > +
> > +	/* enable self wakeup */
> > +	reg_mcr |= FLEXCAN_MCR_WAK_MSK | FLEXCAN_MCR_SLF_WAK;
> > +
> >  	netdev_dbg(dev, "%s: writing mcr=0x%08x", __func__, reg_mcr);
> >  	priv->write(reg_mcr, &regs->mcr);
> >
> > @@ -1240,6 +1275,56 @@ static void unregister_flexcandev(struct
> net_device *dev)
> >  	unregister_candev(dev);
> >  }
> >
> > +static int flexcan_of_parse_stop_mode(struct platform_device *pdev) {
> > +	struct net_device *dev = platform_get_drvdata(pdev);
> > +	struct device_node *np = pdev->dev.of_node;
> > +	struct device_node *node;
> > +	struct flexcan_priv *priv;
> > +	phandle phandle;
> > +	u32 out_val[5];
> > +	int ret;
> > +
> > +	if (!np)
> > +		return -EINVAL;
> > +
> > +	/* stop mode property format is:
> > +	 * <&gpr req_gpr req_bit ack_gpr ack_bit>.
> > +	 */
> > +	ret = of_property_read_u32_array(np, "fsl,stop-mode", out_val, 5);
> > +	if (ret) {
> > +		dev_dbg(&pdev->dev, "no stop-mode property\n");
> > +		return ret;
> > +	}
> > +	phandle = *out_val;
> > +
> > +	node = of_find_node_by_phandle(phandle);
> > +	if (!node) {
> > +		dev_dbg(&pdev->dev, "could not find gpr node by phandle\n");
> > +		return PTR_ERR(node);
> > +	}
> > +
> > +	priv = netdev_priv(dev);
> > +	priv->stm.gpr = syscon_node_to_regmap(node);
> > +	if (IS_ERR(priv->stm.gpr)) {
> > +		dev_dbg(&pdev->dev, "could not find gpr regmap\n");
> > +		return PTR_ERR(priv->stm.gpr);
> > +	}
> > +
> > +	of_node_put(node);
> > +
> > +	priv->stm.req_gpr = out_val[1];
> > +	priv->stm.req_bit = out_val[2];
> > +	priv->stm.ack_gpr = out_val[3];
> > +	priv->stm.ack_bit = out_val[4];
> > +
> > +	dev_dbg(&pdev->dev, "gpr %s req_gpr 0x%x req_bit %u ack_gpr 0x%x
> ack_bit %u\n",
> > +			node->full_name, priv->stm.req_gpr,
> > +			priv->stm.req_bit, priv->stm.ack_gpr,
> > +			priv->stm.ack_bit);
> > +	return 0;
> > +}
> > +
> >  static const struct of_device_id flexcan_of_match[] = {
> >  	{ .compatible = "fsl,imx6q-flexcan", .data = &fsl_imx6q_devtype_data, },
> >  	{ .compatible = "fsl,imx28-flexcan", .data =
> > &fsl_imx28_devtype_data, }, @@ -1271,6 +1356,7 @@ static int
> flexcan_probe(struct platform_device *pdev)
> >  	struct flexcan_regs __iomem *regs;
> >  	int err, irq;
> >  	u32 clock_freq = 0;
> > +	int wakeup = 1;
> 
> Make it a bool.
> Why is is default enabled?
> See below.
> 
> >
> >  	reg_xceiver = devm_regulator_get(&pdev->dev, "xceiver");
> >  	if (PTR_ERR(reg_xceiver) == -EPROBE_DEFER) @@ -1400,6 +1486,16 @@
> > static int flexcan_probe(struct platform_device *pdev)
> >
> >  	devm_can_led_init(dev);
> >
> > +	if (priv->devtype_data->quirks & FLEXCAN_QUIRK_USE_OFF_TIMESTAMP)
> {
> 
> Please add another QUIRK.
> 
> > +		err = flexcan_of_parse_stop_mode(pdev);
> > +		if (err) {
> > +			wakeup = 0;
> > +			dev_dbg(&pdev->dev, "failed to parse stop-mode\n");
> > +		}
> > +	}
> > +
> > +	device_set_wakeup_capable(&pdev->dev, wakeup);
> 
> What about moving this into "flexcan_of_parse_stop_mode(pdev);", and
> rename this function into ..._setup_stop_mode() or something similar.
I have renamed the function and moved "device_set_wakeup_capable()" into this function.

Best Regards,
Joakim Zhang

> > +
> >  	pm_runtime_put(&pdev->dev);
> >
> >  	dev_info(&pdev->dev, "device registered (reg_base=%p, irq=%d)\n", @@
> > -1437,10 +1533,18 @@ static int __maybe_unused flexcan_suspend(struct
> device *device)
> >  	int err = 0;
> >
> >  	if (netif_running(dev)) {
> > -		err = flexcan_chip_disable(priv);
> > -		if (err)
> > -			return err;
> > -		err = pm_runtime_force_suspend(device);
> > +		/* if wakeup is enabled, enter stop mode
> > +		 * else enter disabled mode.
> > +		 */
> > +		if (device_may_wakeup(device)) {
> > +			enable_irq_wake(dev->irq);
> > +			flexcan_enter_stop_mode(priv);
> > +		} else {
> > +			err = flexcan_chip_disable(priv);
> > +			if (err)
> > +				return err;
> > +			err = pm_runtime_force_suspend(device);
> > +		}
> >
> >  		netif_stop_queue(dev);
> >  		netif_device_detach(dev);
> > @@ -1461,10 +1565,12 @@ static int __maybe_unused
> flexcan_resume(struct device *device)
> >  		netif_device_attach(dev);
> >  		netif_start_queue(dev);
> >
> > -		err = pm_runtime_force_resume(device);
> > -		if (err)
> > -			return err;
> > -		err = flexcan_chip_enable(priv);
> > +		if (!device_may_wakeup(device)) {
> > +			err = pm_runtime_force_resume(device);
> > +			if (err)
> > +				return err;
> > +			err = flexcan_chip_enable(priv);
> > +		}
> >  	}
> >  	return err;
> >  }
> > @@ -1489,10 +1595,27 @@ static int __maybe_unused
> flexcan_runtime_resume(struct device *device)
> >  	return 0;
> >  }
> >
> > +static int __maybe_unused flexcan_noirq_resume(struct device *device)
> > +{
> > +	struct net_device *dev = dev_get_drvdata(device);
> > +	struct flexcan_priv *priv = netdev_priv(dev);
> > +
> > +	/* exit stop mode during noirq stage avoid continuously entering
> > +	 * wakeup ISR before CAN resume back.
> > +	 */
> > +	if (netif_running(dev) && device_may_wakeup(device)) {
> > +		disable_irq_wake(dev->irq);
> > +		flexcan_exit_stop_mode(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)
> > +	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(NULL, flexcan_noirq_resume)
> >  };
> >
> >  static struct platform_driver flexcan_driver = {
> >
> 
> Marc
> 
> --
> Pengutronix e.K.                  | Marc Kleine-Budde           |
> Industrial Linux Solutions        | Phone: +49-231-2826-924     |
> Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
> Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |

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