[PATCH V3 2/2] can: xilinx_can: Add Transmitter delay compensation (TDC) feature support
Marc Kleine-Budde
mkl at pengutronix.de
Thu Jun 9 01:31:39 PDT 2022
On 09.06.2022 13:54:33, Srinivas Neeli wrote:
> Added Transmitter delay compensation (TDC) feature support.
> In the case of higher measured loop delay with higher baud rates,
> observed bit stuff errors. By enabling the TDC feature in
> CANFD controllers, will compensate for the measure loop delay in
> the receive path.
>
> Signed-off-by: Srinivas Neeli <srinivas.neeli at xilinx.com>
> ---
> Changes in V3:
> -Implemented GENMASK,FIELD_PERP & FIELD_GET Calls.
> -Implemented TDC feature for all Xilinx CANFD controllers.
> -corrected prescalar to prescaler(typo).
> Changes in V2:
> -Created two patchs one for revert another for TDC support.
> ---
> drivers/net/can/xilinx_can.c | 48 ++++++++++++++++++++++++++++++++----
> 1 file changed, 43 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c
> index e179d311aa28..288be69c0aed 100644
> --- a/drivers/net/can/xilinx_can.c
> +++ b/drivers/net/can/xilinx_can.c
> @@ -1,7 +1,7 @@
> // SPDX-License-Identifier: GPL-2.0-or-later
> /* Xilinx CAN device driver
> *
> - * Copyright (C) 2012 - 2014 Xilinx, Inc.
> + * Copyright (C) 2012 - 2022 Xilinx, Inc.
> * Copyright (C) 2009 PetaLogix. All rights reserved.
> * Copyright (C) 2017 - 2018 Sandvik Mining and Construction Oy
> *
> @@ -9,6 +9,7 @@
> * This driver is developed for Axi CAN IP and for Zynq CANPS Controller.
> */
>
> +#include <linux/bitfield.h>
> #include <linux/clk.h>
> #include <linux/errno.h>
> #include <linux/init.h>
> @@ -99,6 +100,7 @@ enum xcan_reg {
> #define XCAN_ESR_STER_MASK 0x00000004 /* Stuff error */
> #define XCAN_ESR_FMER_MASK 0x00000002 /* Form error */
> #define XCAN_ESR_CRCER_MASK 0x00000001 /* CRC error */
> +#define XCAN_SR_TDCV_MASK GENMASK(22, 16) /* TDCV Value */
> #define XCAN_SR_TXFLL_MASK 0x00000400 /* TX FIFO is full */
> #define XCAN_SR_ESTAT_MASK 0x00000180 /* Error status */
> #define XCAN_SR_ERRWRN_MASK 0x00000040 /* Error warning */
> @@ -132,6 +134,8 @@ enum xcan_reg {
> #define XCAN_DLCR_BRS_MASK 0x04000000 /* BRS Mask in DLC */
>
> /* CAN register bit shift - XCAN_<REG>_<BIT>_SHIFT */
> +#define XCAN_BRPR_TDCO_SHIFT GENMASK(13, 8) /* Transmitter Delay Compensation Offset */
^^^^^
This is a MASK.
> +#define XCAN_BRPR_TDC_ENABLE BIT(16) /* Transmitter Delay Compensation (TDC) Enable */
> #define XCAN_BTR_SJW_SHIFT 7 /* Synchronous jump width */
> #define XCAN_BTR_TS2_SHIFT 4 /* Time segment 2 */
> #define XCAN_BTR_SJW_SHIFT_CANFD 16 /* Synchronous jump width */
> @@ -276,6 +280,16 @@ static const struct can_bittiming_const xcan_data_bittiming_const_canfd2 = {
> .brp_inc = 1,
> };
>
> +/* Transmission Delay Compensation constants for CANFD2.0 and Versal */
> +static const struct can_tdc_const xcan_tdc_const = {
> + .tdcv_min = 0,
> + .tdcv_max = 0, /* Manual mode not supported. */
> + .tdco_min = 0,
> + .tdco_max = 64,
> + .tdcf_min = 0, /* Filter window not supported */
> + .tdcf_max = 0,
> +};
> +
> /**
> * xcan_write_reg_le - Write a value to the device register little endian
> * @priv: Driver private data structure
> @@ -405,7 +419,7 @@ static int xcan_set_bittiming(struct net_device *ndev)
> return -EPERM;
> }
>
> - /* Setting Baud Rate prescalar value in BRPR Register */
> + /* Setting Baud Rate prescaler value in BRPR Register */
unrelated change, please make it a separate patch
> btr0 = (bt->brp - 1);
>
> /* Setting Time Segment 1 in BTR Register */
> @@ -422,8 +436,12 @@ static int xcan_set_bittiming(struct net_device *ndev)
>
> if (priv->devtype.cantype == XAXI_CANFD ||
> priv->devtype.cantype == XAXI_CANFD_2_0) {
> - /* Setting Baud Rate prescalar value in F_BRPR Register */
> + /* Setting Baud Rate prescaler value in F_BRPR Register */
same
> btr0 = dbt->brp - 1;
> + if (can_tdc_is_enabled(&priv->can))
> + btr0 |=
> + FIELD_PREP(XCAN_BRPR_TDCO_SHIFT, priv->can.tdc.tdco) |
> + XCAN_BRPR_TDC_ENABLE;
>
> /* Setting Time Segment 1 in BTR Register */
> btr1 = dbt->prop_seg + dbt->phase_seg1 - 1;
> @@ -1483,6 +1501,22 @@ static int xcan_get_berr_counter(const struct net_device *ndev,
> return 0;
> }
>
> +/**
> + * xcan_get_auto_tdcv - Get Transmitter Delay Compensation Value
> + * @ndev: Pointer to net_device structure
> + * @tdcv: Pointer to TDCV value
> + *
> + * Return: 0 on success
> + */
> +static int xcan_get_auto_tdcv(const struct net_device *ndev, u32 *tdcv)
> +{
> + struct xcan_priv *priv = netdev_priv(ndev);
> +
> + *tdcv = FIELD_GET(XCAN_SR_TDCV_MASK, priv->read_reg(priv, XCAN_SR_OFFSET));
> +
> + return 0;
> +}
> +
> static const struct net_device_ops xcan_netdev_ops = {
> .ndo_open = xcan_open,
> .ndo_stop = xcan_close,
> @@ -1744,8 +1778,12 @@ static int xcan_probe(struct platform_device *pdev)
> &xcan_data_bittiming_const_canfd2;
>
> if (devtype->cantype == XAXI_CANFD ||
> - devtype->cantype == XAXI_CANFD_2_0)
> - priv->can.ctrlmode_supported |= CAN_CTRLMODE_FD;
> + devtype->cantype == XAXI_CANFD_2_0) {
> + priv->can.ctrlmode_supported |= CAN_CTRLMODE_FD |
> + CAN_CTRLMODE_TDC_AUTO;
> + priv->can.do_get_auto_tdcv = xcan_get_auto_tdcv;
> + priv->can.tdc_const = &xcan_tdc_const;
> + }
>
> priv->reg_base = addr;
> priv->tx_max = tx_max;
> --
> 2.25.1
>
>
Otherwise looks good.
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 |
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 488 bytes
Desc: not available
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20220609/7206dc5e/attachment.sig>
More information about the linux-arm-kernel
mailing list