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Message-ID: <ZpaF4Wc70VuV4Cti@lizhi-Precision-Tower-5810>
Date: Tue, 16 Jul 2024 10:40:31 -0400
From: Frank Li <Frank.li@....com>
To: Marc Kleine-Budde <mkl@...gutronix.de>
Cc: Vincent Mailhol <mailhol.vincent@...adoo.fr>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, linux-can@...r.kernel.org,
	netdev@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, haibo.chen@....com,
	imx@...ts.linux.dev, han.xu@....com
Subject: Re: [PATCH v2 4/4] can: flexcan: add wakeup support for imx95

On Tue, Jul 16, 2024 at 09:06:14AM +0200, Marc Kleine-Budde wrote:
> On 15.07.2024 17:27:23, Frank Li wrote:
> > From: Haibo Chen <haibo.chen@....com>
> > 
> > iMX95 defines a bit in GPR that sets/unsets the IPG_STOP signal to the
> > FlexCAN module, controlling its entry into STOP mode. Wakeup should work
> > even if FlexCAN is in STOP mode.
> > 
> > Due to iMX95 architecture design, the A-Core cannot access GPR; only the
> > system manager (SM) can configure GPR. To support the wakeup feature,
> > follow these steps:
> > 
> > - For suspend:
> >   1) During Linux suspend, when CAN suspends, do nothing for GPR and keep
> >      CAN-related clocks on.
> >   2) In ATF, check whether CAN needs to support wakeup; if yes, send a
> >      request to SM through the SCMI protocol.
> >   3) In SM, configure the GPR and unset IPG_STOP.
> >   4) A-Core suspends.
> > 
> > - For wakeup and resume:
> >   1) A-Core wakeup event arrives.
> >   2) In SM, deassert IPG_STOP.
> >   3) Linux resumes.
> > 
> > Add a new fsl_imx95_devtype_data and FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI to
> > reflect this.
> > 
> > Reviewed-by: Han Xu <han.xu@....com>
> > Signed-off-by: Haibo Chen <haibo.chen@....com>
> > Reviewed-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
> > Signed-off-by: Frank Li <Frank.Li@....com>
> > ---
> >  drivers/net/can/flexcan/flexcan-core.c | 49 ++++++++++++++++++++++++++++++----
> >  drivers/net/can/flexcan/flexcan.h      |  2 ++
> >  2 files changed, 46 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/net/can/flexcan/flexcan-core.c b/drivers/net/can/flexcan/flexcan-core.c
> > index f6e609c388d55..fe972d5b8fbe0 100644
> > --- a/drivers/net/can/flexcan/flexcan-core.c
> > +++ b/drivers/net/can/flexcan/flexcan-core.c
> > @@ -354,6 +354,14 @@ static struct flexcan_devtype_data fsl_imx93_devtype_data = {
> >  		FLEXCAN_QUIRK_SUPPORT_RX_MAILBOX_RTR,
> >  };
> >  
> > +static const struct flexcan_devtype_data fsl_imx95_devtype_data = {
> > +	.quirks = FLEXCAN_QUIRK_DISABLE_RXFG | FLEXCAN_QUIRK_ENABLE_EACEN_RRS |
> > +		FLEXCAN_QUIRK_DISABLE_MECR | FLEXCAN_QUIRK_USE_RX_MAILBOX |
> > +		FLEXCAN_QUIRK_BROKEN_PERR_STATE | FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI |
> > +		FLEXCAN_QUIRK_SUPPORT_FD | FLEXCAN_QUIRK_SUPPORT_ECC |
> > +		FLEXCAN_QUIRK_SUPPORT_RX_MAILBOX |
> > +		FLEXCAN_QUIRK_SUPPORT_RX_MAILBOX_RTR,
> 
> Please keep the flags sorted by their value.
> 
> > +};
> 
> Please add a newline here.
> 
> >  static const struct flexcan_devtype_data fsl_vf610_devtype_data = {
> >  	.quirks = FLEXCAN_QUIRK_DISABLE_RXFG | FLEXCAN_QUIRK_ENABLE_EACEN_RRS |
> >  		FLEXCAN_QUIRK_DISABLE_MECR | FLEXCAN_QUIRK_USE_RX_MAILBOX |
> > @@ -548,6 +556,13 @@ static inline int flexcan_enter_stop_mode(struct flexcan_priv *priv)
> >  	} else if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_GPR) {
> >  		regmap_update_bits(priv->stm.gpr, priv->stm.req_gpr,
> >  				   1 << priv->stm.req_bit, 1 << priv->stm.req_bit);
> > +	} else if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI) {
> > +		/* For the SCMI mode, driver do nothing, ATF will send request to
> > +		 * SM(system manager, M33 core) through SCMI protocol after linux
> > +		 * suspend. Once SM get this request, it will send IPG_STOP signal
> > +		 * to Flex_CAN, let CAN in STOP mode.
> > +		 */
> > +		return 0;
> >  	}
> >  
> >  	return flexcan_low_power_enter_ack(priv);
> > @@ -559,7 +574,11 @@ static inline int flexcan_exit_stop_mode(struct flexcan_priv *priv)
> >  	u32 reg_mcr;
> >  	int ret;
> >  
> > -	/* remove stop request */
> > +	/* Remove stop request, for FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI,
> > +	 * do nothing here, because ATF already send request to SM before
> > +	 * linux resume. Once SM get this request, it will deassert the
> > +	 * IPG_STOP signal to Flex_CAN.
> > +	 */
> >  	if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_SCFW) {
> >  		ret = flexcan_stop_mode_enable_scfw(priv, false);
> >  		if (ret < 0)
> > @@ -1987,6 +2006,9 @@ static int flexcan_setup_stop_mode(struct platform_device *pdev)
> >  		ret = flexcan_setup_stop_mode_scfw(pdev);
> >  	else if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_GPR)
> >  		ret = flexcan_setup_stop_mode_gpr(pdev);
> > +	else if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI)
> > +		/* ATF will handle all STOP_IPG related work */
> > +		ret = 0;
> >  	else
> >  		/* return 0 directly if doesn't support stop mode feature */
> >  		return 0;
> > @@ -2013,6 +2035,7 @@ static const struct of_device_id flexcan_of_match[] = {
> >  	{ .compatible = "fsl,imx8qm-flexcan", .data = &fsl_imx8qm_devtype_data, },
> >  	{ .compatible = "fsl,imx8mp-flexcan", .data = &fsl_imx8mp_devtype_data, },
> >  	{ .compatible = "fsl,imx93-flexcan", .data = &fsl_imx93_devtype_data, },
> > +	{ .compatible = "fsl,imx95-flexcan", .data = &fsl_imx95_devtype_data, },
> >  	{ .compatible = "fsl,imx6q-flexcan", .data = &fsl_imx6q_devtype_data, },
> >  	{ .compatible = "fsl,imx28-flexcan", .data = &fsl_imx28_devtype_data, },
> >  	{ .compatible = "fsl,imx53-flexcan", .data = &fsl_imx25_devtype_data, },
> > @@ -2311,9 +2334,22 @@ static int __maybe_unused flexcan_noirq_suspend(struct device *device)
> >  	if (netif_running(dev)) {
> >  		int err;
> >  
> > -		if (device_may_wakeup(device))
> > +		if (device_may_wakeup(device)) {
> >  			flexcan_enable_wakeup_irq(priv, true);
> >  
> > +			/* For FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI, it need
>                                                                       needs
> > +			 * ATF to send request to SM through SCMI protocol,
> > +			 * SM will assert the IPG_STOP signal. But all this
> > +			 * works need the CAN clocks keep on.
> > +			 * After the CAN module get the IPG_STOP mode, and
>                                                 gets
> > +			 * switch to STOP mode, whether still keep the CAN
>                            switches
> > +			 * clocks on or gate them off depend on the Hardware
> > +			 * design.
> > +			 */
> > +			if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI)
> > +				return 0;
> > +		}
> > +
> >  		err = pm_runtime_force_suspend(device);
> >  		if (err)
> >  			return err;
> > @@ -2330,9 +2366,12 @@ static int __maybe_unused flexcan_noirq_resume(struct device *device)
> >  	if (netif_running(dev)) {
> >  		int err;
> >  
> > -		err = pm_runtime_force_resume(device);
> > -		if (err)
> > -			return err;
> > +		if (!(device_may_wakeup(device) &&
>                       ^^^^^^^^^^^^^^^^^^^^^^^^
> 
> Where does this come from?

include/linux/pm_wakeup.h

static inline bool device_may_wakeup(struct device *dev)                                            
{                                                                                                   
        return dev->power.can_wakeup && !!dev->power.wakeup;                                        
}

Frank

> 
> > +		      priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI)) {
> > +			err = pm_runtime_force_resume(device);
> > +			if (err)
> > +				return err;
> > +		}
> >  
> >  		if (device_may_wakeup(device))
> >  			flexcan_enable_wakeup_irq(priv, false);
> > diff --git a/drivers/net/can/flexcan/flexcan.h b/drivers/net/can/flexcan/flexcan.h
> > index 025c3417031f4..4933d8c7439e6 100644
> > --- a/drivers/net/can/flexcan/flexcan.h
> > +++ b/drivers/net/can/flexcan/flexcan.h
> > @@ -68,6 +68,8 @@
> >  #define FLEXCAN_QUIRK_SUPPORT_RX_MAILBOX_RTR BIT(15)
> >  /* Device supports RX via FIFO */
> >  #define FLEXCAN_QUIRK_SUPPORT_RX_FIFO BIT(16)
> > +/* Setup stop mode with ATF SCMI protocol to support wakeup */
> > +#define FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI BIT(17)
> >  
> >  struct flexcan_devtype_data {
> >  	u32 quirks;		/* quirks needed for different IP cores */
> > 
> > -- 
> > 2.34.1
> > 
> > 
> 
> regards,
> Marc
> 
> -- 
> Pengutronix e.K.                 | Marc Kleine-Budde          |
> Embedded Linux                   | https://www.pengutronix.de |
> Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
> Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |



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