Date:   Tue, 29 Sep 2020 12:48:55 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Joakim Zhang <qiangqing.zhang@....com>, linux-can@...r.kernel.org
Cc:     linux-imx@....com, netdev@...r.kernel.org
Subject: Re: [PATCH linux-can-next/flexcan 3/4] can: flexcan: add CAN wakeup
 function for i.MX8

On 9/25/20 5:10 PM, Joakim Zhang wrote:
> The System Controller Firmware (SCFW) is a low-level system function
> which runs on a dedicated Cortex-M core to provide power, clock, and
> resource management. It exists on some i.MX8 processors. e.g. i.MX8QM
> (QM, QP), and i.MX8QX (QXP, DX).
> 
> SCU driver manages the IPC interface between host CPU and the
> SCU firmware running on M4.
> 
> For i.MX8, stop mode request is controlled by System Controller Unit(SCU)
> firmware.

As you mentioned in the other mail, some functions are missing from the
> 
> Signed-off-by: Joakim Zhang <qiangqing.zhang@....com>
> ---
>  drivers/net/can/flexcan.c | 81 ++++++++++++++++++++++++++++++++-------
>  1 file changed, 68 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
> index 8c8753f77764..41b52cb56f93 100644
> --- a/drivers/net/can/flexcan.c
> +++ b/drivers/net/can/flexcan.c
> @@ -9,6 +9,7 @@
>  //
>  // Based on code originally by Andrey Volkov <avolkov@...ma-el.com>
>  
> +#include <dt-bindings/firmware/imx/rsrc.h>
>  #include <linux/bitfield.h>
>  #include <linux/can.h>
>  #include <linux/can/dev.h>
> @@ -17,6 +18,7 @@
>  #include <linux/can/rx-offload.h>
>  #include <linux/clk.h>
>  #include <linux/delay.h>
> +#include <linux/firmware/imx/sci.h>
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/mfd/syscon.h>
> @@ -240,6 +242,8 @@
>  #define FLEXCAN_QUIRK_SETUP_STOP_MODE BIT(8)

rename this into "FLEXCAN_QUIRK_SETUP_STOP_MODE_GPR"

>  /* Support CAN-FD mode */
>  #define FLEXCAN_QUIRK_SUPPORT_FD BIT(9)
> +/* Use System Controller Firmware */
> +#define FLEXCAN_QUIRK_USE_SCFW BIT(10)

...and this into FLEXCAN_QUIRK_SETUP_STOP_MODE_SCFW

>  
>  /* Structure of the message buffer */
>  struct flexcan_mb {
> @@ -358,6 +362,9 @@ struct flexcan_priv {
>  	struct regulator *reg_xceiver;
>  	struct flexcan_stop_mode stm;
>  
> +	/* IPC handle when enable stop mode by System Controller firmware(scfw) */
> +	struct imx_sc_ipc *sc_ipc_handle;
> +
>  	/* Read and Write APIs */
>  	u32 (*read)(void __iomem *addr);
>  	void (*write)(u32 val, void __iomem *addr);
> @@ -387,7 +394,8 @@ static const struct flexcan_devtype_data fsl_imx6q_devtype_data = {
>  static const struct flexcan_devtype_data fsl_imx8qm_devtype_data = {
>  	.quirks = FLEXCAN_QUIRK_DISABLE_RXFG | FLEXCAN_QUIRK_ENABLE_EACEN_RRS |
>  		FLEXCAN_QUIRK_USE_OFF_TIMESTAMP | FLEXCAN_QUIRK_BROKEN_PERR_STATE |
> -		FLEXCAN_QUIRK_SUPPORT_FD,
> +		FLEXCAN_QUIRK_SUPPORT_FD | FLEXCAN_QUIRK_SETUP_STOP_MODE |
> +		FLEXCAN_QUIRK_USE_SCFW,
>  };
>  
>  static struct flexcan_devtype_data fsl_imx8mp_devtype_data = {
> @@ -546,6 +554,25 @@ static void flexcan_enable_wakeup_irq(struct flexcan_priv *priv, bool enable)
>  	priv->write(reg_mcr, &regs->mcr);
>  }
>  
> +static void flexcan_stop_mode_enable_scfw(struct flexcan_priv *priv, bool enabled)
> +{
> +	struct device_node *np = priv->dev->of_node;
> +	u32 rsrc_id, val;
> +	int idx;
> +
> +	idx = of_alias_get_id(np, "can");
> +	if (idx == 0)
> +		rsrc_id = IMX_SC_R_CAN_0;
> +	else if (idx == 1)
> +		rsrc_id = IMX_SC_R_CAN_1;
> +	else
> +		rsrc_id = IMX_SC_R_CAN_2;

This looks too fragile to me. Better add a property to the DT which indicates
the index.

> +
> +	val = enabled ? 1 : 0;

Please use an if() here.

> +	/* stop mode request */
> +	imx_sc_misc_set_control(priv->sc_ipc_handle, rsrc_id, IMX_SC_C_IPG_STOP, val);
> +}
> +
>  static inline int flexcan_enter_stop_mode(struct flexcan_priv *priv)
>  {
>  	struct flexcan_regs __iomem *regs = priv->regs;
> @@ -555,9 +582,12 @@ static inline int flexcan_enter_stop_mode(struct flexcan_priv *priv)
>  	reg_mcr |= FLEXCAN_MCR_SLF_WAK;
>  	priv->write(reg_mcr, &regs->mcr);
>  
> -	/* enable stop request */
> -	regmap_update_bits(priv->stm.gpr, priv->stm.req_gpr,
> -			   1 << priv->stm.req_bit, 1 << priv->stm.req_bit);
> +	 /* enable stop request */
> +	if (priv->devtype_data->quirks & FLEXCAN_QUIRK_USE_SCFW)
> +		flexcan_stop_mode_enable_scfw(priv, true);

error handling?

> +	else
> +		regmap_update_bits(priv->stm.gpr, priv->stm.req_gpr,
> +				   1 << priv->stm.req_bit, 1 << priv->stm.req_bit);
>  
>  	return flexcan_low_power_enter_ack(priv);
>  }
> @@ -568,8 +598,11 @@ static inline int flexcan_exit_stop_mode(struct flexcan_priv *priv)
>  	u32 reg_mcr;
>  
>  	/* remove stop request */
> -	regmap_update_bits(priv->stm.gpr, priv->stm.req_gpr,
> -			   1 << priv->stm.req_bit, 0);
> +	if (priv->devtype_data->quirks & FLEXCAN_QUIRK_USE_SCFW)
> +		flexcan_stop_mode_enable_scfw(priv, false);

error handling?

> +	else
> +		regmap_update_bits(priv->stm.gpr, priv->stm.req_gpr,
> +				   1 << priv->stm.req_bit, 0);
>  
>  	reg_mcr = priv->read(&regs->mcr);
>  	reg_mcr &= ~FLEXCAN_MCR_SLF_WAK;
> @@ -1927,11 +1960,6 @@ static int flexcan_setup_stop_mode(struct platform_device *pdev)
>  		gpr_np->full_name, priv->stm.req_gpr, priv->stm.req_bit,
>  		priv->stm.ack_gpr, priv->stm.ack_bit);
>  
> -	device_set_wakeup_capable(&pdev->dev, true);
> -
> -	if (of_property_read_bool(np, "wakeup-source"))
> -		device_set_wakeup_enable(&pdev->dev, true);
> -
>  	return 0;
>  
>  out_put_node:
> @@ -1939,6 +1967,23 @@ static int flexcan_setup_stop_mode(struct platform_device *pdev)
>  	return ret;
>  }
>  
> +static int flexcan_setup_stop_mode_scfw(struct platform_device *pdev)
> +{
> +	struct net_device *dev = platform_get_drvdata(pdev);
> +	struct flexcan_priv *priv;
> +	int ret;
> +
> +	priv = netdev_priv(dev);
> +
> +	ret = imx_scu_get_handle(&priv->sc_ipc_handle);

this function can return -EPROBE_DEFER

https://elixir.bootlin.com/linux/latest/source/drivers/firmware/imx/imx-scu.c#L97

> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "get ipc handle used by SCU failed\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
>  static const struct of_device_id flexcan_of_match[] = {
>  	{ .compatible = "fsl,imx8mp-flexcan", .data = &fsl_imx8mp_devtype_data, },
>  	{ .compatible = "fsl,imx8qm-flexcan", .data = &fsl_imx8qm_devtype_data, },
> @@ -2088,9 +2133,19 @@ static int flexcan_probe(struct platform_device *pdev)
>  	devm_can_led_init(dev);
>  
>  	if (priv->devtype_data->quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE) {
> -		err = flexcan_setup_stop_mode(pdev);

what about renaming the flexcan_setup_stop_mode() to
flexcan_setup_stop_mode_gpr() and moving this below into a function called
flexcan_setup_stop_mode().

> -		if (err)
> +		if (priv->devtype_data->quirks & FLEXCAN_QUIRK_USE_SCFW)
> +			err = flexcan_setup_stop_mode_scfw(pdev);
> +		else
> +			err = flexcan_setup_stop_mode(pdev);
> +
> +		if (err) {
>  			dev_dbg(&pdev->dev, "failed to setup stop-mode\n");
> +		} else {
> +			device_set_wakeup_capable(&pdev->dev, true);
> +
> +			if (of_property_read_bool(pdev->dev.of_node, "wakeup-source"))
> +				device_set_wakeup_enable(&pdev->dev, true);
> +		}
>  	}
>  
>  	return 0;
> 

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |



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