Date:   Mon, 19 Oct 2020 10:15:39 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Joakim Zhang <qiangqing.zhang@....com>, robh+dt@...nel.org,
        shawnguo@...nel.org, s.hauer@...gutronix.de
Cc:     kernel@...gutronix.de, linux-imx@....com, victor.liu@....com,
        linux-can@...r.kernel.org, pankaj.bansal@....com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 8/8] can: flexcan: add CAN wakeup function for i.MX8QM

On 10/19/20 5:57 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.MX8QM, stop mode request is controlled by System Controller Unit(SCU)
> firmware, this patch introduces FLEXCAN_QUIRK_SETUP_STOP_MODE_SCFW quirk
> for this function.
> 
> Signed-off-by: Joakim Zhang <qiangqing.zhang@....com>
> ---
>  drivers/net/can/flexcan.c | 131 +++++++++++++++++++++++++++++++++-----
>  1 file changed, 114 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
> index c0cdee904ca7..8ad5065c918f 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>
> @@ -203,6 +205,8 @@
>  
>  #define FLEXCAN_TIMEOUT_US		(250)
>  
> +#define FLEXCAN_IMX_SC_R_CAN(x)		(IMX_SC_R_CAN_0 + (x))

Why not move it into the appropriate svc header file?

> +
>  /* FLEXCAN hardware feature flags
>   *
>   * Below is some version info we got:
> @@ -242,6 +246,8 @@
>  #define FLEXCAN_QUIRK_SUPPORT_FD BIT(9)
>  /* support memory detection and correction */
>  #define FLEXCAN_QUIRK_SUPPORT_ECC BIT(10)
> +/* Setup stop mode with SCU firmware to support wakeup */
> +#define FLEXCAN_QUIRK_SETUP_STOP_MODE_SCFW BIT(11)
>  
>  /* Structure of the message buffer */
>  struct flexcan_mb {
> @@ -347,6 +353,7 @@ struct flexcan_priv {
>  	u8 mb_count;
>  	u8 mb_size;
>  	u8 clk_src;	/* clock source of CAN Protocol Engine */
> +	u8 can_idx;
>  
>  	u64 rx_mask;
>  	u64 tx_mask;
> @@ -358,6 +365,9 @@ struct flexcan_priv {
>  	struct regulator *reg_xceiver;
>  	struct flexcan_stop_mode stm;
>  
> +	/* IPC handle when setup 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 +397,7 @@ 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_SCFW,
>  };
>  
>  static struct flexcan_devtype_data fsl_imx8mp_devtype_data = {
> @@ -546,18 +556,42 @@ static void flexcan_enable_wakeup_irq(struct flexcan_priv *priv, bool enable)
>  	priv->write(reg_mcr, &regs->mcr);
>  }
>  
> +static int flexcan_stop_mode_enable_scfw(struct flexcan_priv *priv, bool enabled)
> +{
> +	u8 idx = priv->can_idx;
> +	u32 rsrc_id, val;
> +
> +	rsrc_id = FLEXCAN_IMX_SC_R_CAN(idx);
> +
> +	if (enabled)
> +		val = 1;
> +	else
> +		val = 0;
> +
> +	/* stop mode request via scu firmware */
> +	return 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;
>  	u32 reg_mcr;
> +	int ret;
>  
>  	reg_mcr = priv->read(&regs->mcr);
>  	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);
> +	if (priv->devtype_data->quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_SCFW) {
> +		ret = flexcan_stop_mode_enable_scfw(priv, true);
> +		if (ret < 0)
> +			return ret;
> +	} 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);
>  }
> @@ -566,10 +600,17 @@ static inline int flexcan_exit_stop_mode(struct flexcan_priv *priv)
>  {
>  	struct flexcan_regs __iomem *regs = priv->regs;
>  	u32 reg_mcr;
> +	int ret;
>  
>  	/* 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_SETUP_STOP_MODE_SCFW) {
> +		ret = flexcan_stop_mode_enable_scfw(priv, false);
> +		if (ret < 0)
> +			return ret;
> +	} 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;
> @@ -1838,7 +1879,7 @@ static void unregister_flexcandev(struct net_device *dev)
>  	unregister_candev(dev);
>  }
>  
> -static int flexcan_setup_stop_mode(struct platform_device *pdev)
> +static int flexcan_setup_stop_mode_gpr(struct platform_device *pdev)
>  {
>  	struct net_device *dev = platform_get_drvdata(pdev);
>  	struct device_node *np = pdev->dev.of_node;
> @@ -1883,11 +1924,6 @@ static int flexcan_setup_stop_mode(struct platform_device *pdev)
>  		"gpr %s req_gpr=0x02%x req_bit=%u\n",
>  		gpr_np->full_name, priv->stm.req_gpr, priv->stm.req_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:
> @@ -1895,6 +1931,64 @@ 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;
> +	u8 can_idx;
> +	int ret;
> +
> +	ret = of_property_read_u8(pdev->dev.of_node, "fsl,scu-index", &can_idx);
> +	if (ret < 0) {
> +		dev_dbg(&pdev->dev, "failed to get scu index\n");
> +		return ret;
> +	}
> +
> +	priv = netdev_priv(dev);
> +	priv->can_idx = can_idx;
> +
> +	/* this function could be defered probe, return -EPROBE_DEFER */
> +	ret = imx_scu_get_handle(&priv->sc_ipc_handle);
> +	if (ret < 0) {
> +		dev_dbg(&pdev->dev, "get ipc handle used by SCU failed\n");
> +		return ret;
> +	}

Don't print an error message on -EPROBE_DEFER.

> +
> +	return 0;
> +}
> +
> +/* flexcan_setup_stop_mode - Setup stop mode for wakeup
> + *
> + * Return: = 0 setup stop mode successfully or doesn't support this feature
> + *         < 0 fail to setup stop mode (could be defered probe)
> + */
> +static int flexcan_setup_stop_mode(struct platform_device *pdev)
> +{
> +	struct net_device *dev = platform_get_drvdata(pdev);
> +	struct flexcan_priv *priv;
> +	int ret;
> +
> +	priv = netdev_priv(dev);
> +
> +	if (priv->devtype_data->quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_SCFW)
> +		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
> +		/* return 0 directly if doesn't support stop mode feature */
> +		return 0;
> +
> +	if (ret)
> +		return ret;
> +
> +	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;
> +}
> +
>  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, },
> @@ -2040,17 +2134,19 @@ static int flexcan_probe(struct platform_device *pdev)
>  		goto failed_register;
>  	}
>  
> +	err = flexcan_setup_stop_mode(pdev);
> +	if (err < 0) {
> +		dev_err(&pdev->dev, "setup stop mode failed\n");
> +		goto failed_canregister;
> +	}
> +
>  	of_can_transceiver(dev);
>  	devm_can_led_init(dev);
>  
> -	if (priv->devtype_data->quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_GPR) {
> -		err = flexcan_setup_stop_mode(pdev);
> -		if (err)
> -			dev_dbg(&pdev->dev, "failed to setup stop-mode\n");
> -	}
> -
>  	return 0;
>  
> + failed_canregister:
> +	unregister_flexcandev(dev);
>   failed_register:
>  	pm_runtime_put_noidle(&pdev->dev);
>  	pm_runtime_disable(&pdev->dev);
> @@ -2062,6 +2158,7 @@ static int flexcan_remove(struct platform_device *pdev)
>  {
>  	struct net_device *dev = platform_get_drvdata(pdev);
>  
> +	device_set_wakeup_enable(&pdev->dev, false);

Please make this a seperate patch, as it fixes a bug.

>  	unregister_flexcandev(dev);
>  	pm_runtime_disable(&pdev->dev);
>  	free_candev(dev);
> 

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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