Re: [PATCH v2 4/4] can: flexcan: add wakeup support for imx95

[Marc Kleine-Budde]

On 15.07.2024 17:27:23, Frank Li wrote:
> From: Haibo Chen <haibo.chen@xxxxxxx>
> 
> 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@xxxxxxx>
> Signed-off-by: Haibo Chen <haibo.chen@xxxxxxx>
> Reviewed-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
> Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
> ---
>  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?

> +		      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

-- 
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