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Message-ID: <20230904-postal-easily-aaec334f8d65-mkl@pengutronix.de>
Date:   Mon, 4 Sep 2023 17:04:34 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Srinivas Goud <srinivas.goud@....com>
Cc:     wg@...ndegger.com, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        p.zabel@...gutronix.de, git@....com, michal.simek@....com,
        linux-can@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, appana.durga.rao@...inx.com,
        naga.sureshkumar.relli@...inx.com
Subject: Re: [PATCH v4 2/3] can: xilinx_can: Add ECC support

On 01.09.2023 14:10:44, Srinivas Goud wrote:
> Add ECC support for Xilinx CAN Controller, so this driver reports
> 1bit/2bit ECC errors for FIFO's based on ECC error interrupt.
> ECC feature for Xilinx CAN Controller selected through
> 'xlnx,has-ecc' DT property
> 
> Signed-off-by: Srinivas Goud <srinivas.goud@....com>
> ---
> Changes in v4:
> None
> 
> Changes in v3:
> None
> 
> Changes in v2:
> Address review comments
> 
>  drivers/net/can/xilinx_can.c | 129 ++++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 114 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c
> index abe58f1..798b32b 100644
> --- a/drivers/net/can/xilinx_can.c
> +++ b/drivers/net/can/xilinx_can.c
> @@ -53,18 +53,23 @@ enum xcan_reg {
>  	XCAN_AFR_OFFSET		= 0x60, /* Acceptance Filter */
>  
>  	/* only on CAN FD cores */
> -	XCAN_F_BRPR_OFFSET	= 0x088, /* Data Phase Baud Rate
> -					  * Prescaler
> -					  */
> -	XCAN_F_BTR_OFFSET	= 0x08C, /* Data Phase Bit Timing */
> -	XCAN_TRR_OFFSET		= 0x0090, /* TX Buffer Ready Request */
> -	XCAN_AFR_EXT_OFFSET	= 0x00E0, /* Acceptance Filter */
> -	XCAN_FSR_OFFSET		= 0x00E8, /* RX FIFO Status */
> -	XCAN_TXMSG_BASE_OFFSET	= 0x0100, /* TX Message Space */

These look like unrelated changes to me. Either move them into a
separate patch (before you add the new offsets) or remove them
completely. Please use tabs not spaces for indention, as the rest of
this file does.

> +	XCAN_F_BRPR_OFFSET	= 0x88, /* Data Phase Baud Rate Prescaler */
> +	XCAN_F_BTR_OFFSET	= 0x8C, /* Data Phase Bit Timing */
> +	XCAN_TRR_OFFSET		= 0x90, /* TX Buffer Ready Request */
> +
> +	/* only on AXI CAN cores */
> +	XCAN_ECC_CFG_OFFSET     = 0xC8, /* ECC Configuration */
> +	XCAN_TXTLFIFO_ECC_OFFSET        = 0xCC, /* TXTL FIFO ECC error counter */
> +	XCAN_TXOLFIFO_ECC_OFFSET        = 0xD0, /* TXOL FIFO ECC error counter */
> +	XCAN_RXFIFO_ECC_OFFSET          = 0xD4, /* RX FIFO ECC error counter */
> +
> +	XCAN_AFR_EXT_OFFSET	= 0xE0, /* Acceptance Filter */
> +	XCAN_FSR_OFFSET		= 0xE8, /* RX FIFO Status */
> +	XCAN_TXMSG_BASE_OFFSET	= 0x100, /* TX Message Space */
> +	XCAN_AFR_2_MASK_OFFSET  = 0xA00, /* Acceptance Filter MASK */
> +	XCAN_AFR_2_ID_OFFSET    = 0xA04, /* Acceptance Filter ID */
>  	XCAN_RXMSG_BASE_OFFSET	= 0x1100, /* RX Message Space */
>  	XCAN_RXMSG_2_BASE_OFFSET	= 0x2100, /* RX Message Space */
> -	XCAN_AFR_2_MASK_OFFSET	= 0x0A00, /* Acceptance Filter MASK */
> -	XCAN_AFR_2_ID_OFFSET	= 0x0A04, /* Acceptance Filter ID */
>  };
>  
>  #define XCAN_FRAME_ID_OFFSET(frame_base)	((frame_base) + 0x00)
> @@ -124,6 +129,12 @@ enum xcan_reg {
>  #define XCAN_IXR_TXFLL_MASK		0x00000004 /* Tx FIFO Full intr */
>  #define XCAN_IXR_TXOK_MASK		0x00000002 /* TX successful intr */
>  #define XCAN_IXR_ARBLST_MASK		0x00000001 /* Arbitration lost intr */
> +#define XCAN_IXR_E2BERX_MASK            BIT(23) /* RX FIFO two bit ECC error */
> +#define XCAN_IXR_E1BERX_MASK            BIT(22) /* RX FIFO one bit ECC error */
> +#define XCAN_IXR_E2BETXOL_MASK          BIT(21) /* TXOL FIFO two bit ECC error */
> +#define XCAN_IXR_E1BETXOL_MASK          BIT(20) /* TXOL FIFO One bit ECC error */
> +#define XCAN_IXR_E2BETXTL_MASK          BIT(19) /* TXTL FIFO Two bit ECC error */
> +#define XCAN_IXR_E1BETXTL_MASK          BIT(18) /* TXTL FIFO One bit ECC error */

Use tabs for indention not spaces as the rest of the file.

>  #define XCAN_IDR_ID1_MASK		0xFFE00000 /* Standard msg identifier */
>  #define XCAN_IDR_SRR_MASK		0x00100000 /* Substitute remote TXreq */
>  #define XCAN_IDR_IDE_MASK		0x00080000 /* Identifier extension */
> @@ -137,6 +148,11 @@ enum xcan_reg {
>  #define XCAN_2_FSR_RI_MASK		0x0000003F /* RX Read Index */
>  #define XCAN_DLCR_EDL_MASK		0x08000000 /* EDL Mask in DLC */
>  #define XCAN_DLCR_BRS_MASK		0x04000000 /* BRS Mask in DLC */
> +#define XCAN_ECC_CFG_REECRX_MASK	BIT(2) /* Reset RX FIFO ECC error counters */
> +#define XCAN_ECC_CFG_REECTXOL_MASK	BIT(1) /* Reset TXOL FIFO ECC error counters */
> +#define XCAN_ECC_CFG_REECTXTL_MASK	BIT(0) /* Reset TXTL FIFO ECC error counters */
> +#define XCAN_ECC_1BIT_CNT_MASK		GENMASK(15, 0) /* FIFO ECC 1bit count mask */
> +#define XCAN_ECC_2BIT_CNT_MASK		GENMASK(31, 16) /* FIFO ECC 2bit count mask */
>  
>  /* CAN register bit shift - XCAN_<REG>_<BIT>_SHIFT */
>  #define XCAN_BRPR_TDC_ENABLE		BIT(16) /* Transmitter Delay Compensation (TDC) Enable */
> @@ -202,6 +218,13 @@ struct xcan_devtype_data {
>   * @devtype:			Device type specific constants
>   * @transceiver:		Optional pointer to associated CAN transceiver
>   * @rstc:			Pointer to reset control
> + * @ecc_enable:			ECC enable flag
> + * @ecc_2bit_rxfifo_cnt:	RXFIFO 2bit ECC count
> + * @ecc_1bit_rxfifo_cnt:	RXFIFO 1bit ECC count
> + * @ecc_2bit_txolfifo_cnt:	TXOLFIFO 2bit ECC count
> + * @ecc_1bit_txolfifo_cnt:	TXOLFIFO 1bit ECC count
> + * @ecc_2bit_txtlfifo_cnt:	TXTLFIFO 2bit ECC count
> + * @ecc_1bit_txtlfifo_cnt:	TXTLFIFO 1bit ECC count
>   */
>  struct xcan_priv {
>  	struct can_priv can;
> @@ -221,6 +244,13 @@ struct xcan_priv {
>  	struct xcan_devtype_data devtype;
>  	struct phy *transceiver;
>  	struct reset_control *rstc;
> +	bool ecc_enable;
> +	u64 ecc_2bit_rxfifo_cnt;
> +	u64 ecc_1bit_rxfifo_cnt;
> +	u64 ecc_2bit_txolfifo_cnt;
> +	u64 ecc_1bit_txolfifo_cnt;
> +	u64 ecc_2bit_txtlfifo_cnt;
> +	u64 ecc_1bit_txtlfifo_cnt;
>  };
>  
>  /* CAN Bittiming constants as per Xilinx CAN specs */
> @@ -523,6 +553,11 @@ static int xcan_chip_start(struct net_device *ndev)
>  		XCAN_IXR_ERROR_MASK | XCAN_IXR_RXOFLW_MASK |
>  		XCAN_IXR_ARBLST_MASK | xcan_rx_int_mask(priv);
>  
> +	if (priv->ecc_enable)
> +		ier |= XCAN_IXR_E2BERX_MASK | XCAN_IXR_E1BERX_MASK |
> +			XCAN_IXR_E2BETXOL_MASK | XCAN_IXR_E1BETXOL_MASK |
> +			XCAN_IXR_E2BETXTL_MASK | XCAN_IXR_E1BETXTL_MASK;
> +
>  	if (priv->devtype.flags & XCAN_FLAG_RXMNF)
>  		ier |= XCAN_IXR_RXMNF_MASK;
>  
> @@ -1127,6 +1162,58 @@ static void xcan_err_interrupt(struct net_device *ndev, u32 isr)
>  		priv->can.can_stats.bus_error++;
>  	}
>  
> +	if (priv->ecc_enable) {
> +		u32 reg_ecc;

It is better to read out all 3 counters directly one after the other,
then reset them. Then do the updates of the stats. This way you can keep
the lock short in the next patch.

Marc

> +
> +		reg_ecc = priv->read_reg(priv, XCAN_RXFIFO_ECC_OFFSET);
> +		if (isr & XCAN_IXR_E2BERX_MASK) {
> +			priv->ecc_2bit_rxfifo_cnt +=
> +				FIELD_GET(XCAN_ECC_2BIT_CNT_MASK, reg_ecc);
> +			netdev_dbg(ndev, "%s: RX FIFO 2bit ECC error count %lld\n",
> +				   __func__, priv->ecc_2bit_rxfifo_cnt);
> +		}
> +		if (isr & XCAN_IXR_E1BERX_MASK) {
> +			priv->ecc_1bit_rxfifo_cnt +=
> +				FIELD_GET(XCAN_ECC_1BIT_CNT_MASK, reg_ecc);
> +			netdev_dbg(ndev, "%s: RX FIFO 1bit ECC error count %lld\n",
> +				   __func__, priv->ecc_1bit_rxfifo_cnt);
> +		}
> +
> +		reg_ecc = priv->read_reg(priv, XCAN_TXOLFIFO_ECC_OFFSET);
> +		if (isr & XCAN_IXR_E2BETXOL_MASK) {
> +			priv->ecc_2bit_txolfifo_cnt +=
> +				FIELD_GET(XCAN_ECC_2BIT_CNT_MASK, reg_ecc);
> +			netdev_dbg(ndev, "%s: TXOL FIFO 2bit ECC error count %lld\n",
> +				   __func__, priv->ecc_2bit_txolfifo_cnt);
> +		}
> +		if (isr & XCAN_IXR_E1BETXOL_MASK) {
> +			priv->ecc_1bit_txolfifo_cnt +=
> +				FIELD_GET(XCAN_ECC_1BIT_CNT_MASK, reg_ecc);
> +			netdev_dbg(ndev, "%s: TXOL FIFO 1bit ECC error count %lld\n",
> +				   __func__, priv->ecc_1bit_txolfifo_cnt);
> +		}
> +
> +		reg_ecc = priv->read_reg(priv, XCAN_TXTLFIFO_ECC_OFFSET);
> +		if (isr & XCAN_IXR_E2BETXTL_MASK) {
> +			priv->ecc_2bit_txtlfifo_cnt +=
> +				FIELD_GET(XCAN_ECC_2BIT_CNT_MASK, reg_ecc);
> +			netdev_dbg(ndev, "%s: TXTL FIFO 2bit ECC error count %lld\n",
> +				   __func__, priv->ecc_2bit_txtlfifo_cnt);
> +		}
> +		if (isr & XCAN_IXR_E1BETXTL_MASK) {
> +			priv->ecc_1bit_txtlfifo_cnt +=
> +				FIELD_GET(XCAN_ECC_1BIT_CNT_MASK, reg_ecc);
> +			netdev_dbg(ndev, "%s: TXTL FIFO 1bit ECC error count %lld\n",
> +				   __func__, priv->ecc_1bit_txtlfifo_cnt);
> +		}
> +
> +		/* The counter reaches its maximum at 0xffff and does not overflow.
> +		 * Accept the small race window between reading and resetting ECC counters.
> +		 */
> +		priv->write_reg(priv, XCAN_ECC_CFG_OFFSET, XCAN_ECC_CFG_REECRX_MASK |
> +				XCAN_ECC_CFG_REECTXOL_MASK | XCAN_ECC_CFG_REECTXTL_MASK);
> +	}
> +
>  	if (cf.can_id) {
>  		struct can_frame *skb_cf;
>  		struct sk_buff *skb = alloc_can_err_skb(ndev, &skb_cf);
> @@ -1354,9 +1441,8 @@ static irqreturn_t xcan_interrupt(int irq, void *dev_id)
>  {
>  	struct net_device *ndev = (struct net_device *)dev_id;
>  	struct xcan_priv *priv = netdev_priv(ndev);
> -	u32 isr, ier;
> -	u32 isr_errors;
>  	u32 rx_int_mask = xcan_rx_int_mask(priv);
> +	u32 isr, ier, isr_errors, mask;
>  
>  	/* Get the interrupt status from Xilinx CAN */
>  	isr = priv->read_reg(priv, XCAN_ISR_OFFSET);
> @@ -1374,10 +1460,17 @@ static irqreturn_t xcan_interrupt(int irq, void *dev_id)
>  	if (isr & XCAN_IXR_TXOK_MASK)
>  		xcan_tx_interrupt(ndev, isr);
>  
> +	mask = XCAN_IXR_ERROR_MASK | XCAN_IXR_RXOFLW_MASK |
> +		XCAN_IXR_BSOFF_MASK | XCAN_IXR_ARBLST_MASK |
> +		XCAN_IXR_RXMNF_MASK;
> +
> +	if (priv->ecc_enable)
> +		mask |= XCAN_IXR_E2BERX_MASK | XCAN_IXR_E1BERX_MASK |
> +			XCAN_IXR_E2BETXOL_MASK | XCAN_IXR_E1BETXOL_MASK |
> +			XCAN_IXR_E2BETXTL_MASK | XCAN_IXR_E1BETXTL_MASK;
> +
>  	/* Check for the type of error interrupt and Processing it */
> -	isr_errors = isr & (XCAN_IXR_ERROR_MASK | XCAN_IXR_RXOFLW_MASK |
> -			    XCAN_IXR_BSOFF_MASK | XCAN_IXR_ARBLST_MASK |
> -			    XCAN_IXR_RXMNF_MASK);
> +	isr_errors = isr & mask;
>  	if (isr_errors) {
>  		priv->write_reg(priv, XCAN_ICR_OFFSET, isr_errors);
>  		xcan_err_interrupt(ndev, isr);
> @@ -1796,6 +1889,7 @@ static int xcan_probe(struct platform_device *pdev)
>  		return -ENOMEM;
>  
>  	priv = netdev_priv(ndev);
> +	priv->ecc_enable = of_property_read_bool(pdev->dev.of_node, "xlnx,has-ecc");
>  	priv->dev = &pdev->dev;
>  	priv->can.bittiming_const = devtype->bittiming_const;
>  	priv->can.do_set_mode = xcan_do_set_mode;
> @@ -1912,6 +2006,11 @@ static int xcan_probe(struct platform_device *pdev)
>  		   priv->reg_base, ndev->irq, priv->can.clock.freq,
>  		   hw_tx_max, priv->tx_max);
>  
> +	if (priv->ecc_enable) {
> +		/* Reset FIFO ECC counters */
> +		priv->write_reg(priv, XCAN_ECC_CFG_OFFSET, XCAN_ECC_CFG_REECRX_MASK |
> +			XCAN_ECC_CFG_REECTXOL_MASK | XCAN_ECC_CFG_REECTXTL_MASK);
> +	}
>  	return 0;
>  
>  err_disableclks:
> -- 
> 2.1.1
> 
> 

-- 
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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