Re: [PATCH v4 2/3] can: xilinx_can: Add ECC support

From: Marc Kleine-Budde
Date: Mon Sep 04 2023 - 11:05:26 EST

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In reply to: Srinivas Goud: "[PATCH v4 2/3] can: xilinx_can: Add ECC support"
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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@xxxxxxx>
> ---
> 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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