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 a controller,
will compensate for the measure loop delay in the receive path.
Signed-off-by: Srinivas Neeli <srinivas.neeli@xxxxxxxxxx>
---
drivers/net/can/xilinx_can.c | 46 +++++++++++++++++++++++++++++++++---
1 file changed, 43 insertions(+), 3 deletions(-)
diff --git a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c
index e179d311aa28..d0edd1bca33c 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
*
@@ -99,6 +99,7 @@ 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 0x007F0000 /* 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 +133,8 @@ 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 8 /* Transmitter Delay Compensation Offset */
+#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 */
@@ -140,6 +143,7 @@ enum xcan_reg {
#define XCAN_IDR_ID2_SHIFT 1 /* Extended Message Identifier */
#define XCAN_DLCR_DLC_SHIFT 28 /* Data length code */
#define XCAN_ESR_REC_SHIFT 8 /* Rx Error Count */
+#define XCAN_SR_TDCV_SHIFT 16 /* TDCV Value */
/* CAN frame length constants */
#define XCAN_FRAME_MAX_DATA_LEN 8
@@ -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
@@ -424,6 +438,11 @@ static int xcan_set_bittiming(struct net_device *ndev)
priv->devtype.cantype == XAXI_CANFD_2_0) {
/* Setting Baud Rate prescalar value in F_BRPR Register */
btr0 = dbt->brp - 1;
+ if (can_tdc_is_enabled(&priv->can)) {
+ btr0 = btr0 |
+ priv->can.tdc.tdco << XCAN_BRPR_TDCO_SHIFT |
+ XCAN_BRPR_TDC_ENABLE;
+ }
/* Setting Time Segment 1 in BTR Register */
btr1 = dbt->prop_seg + dbt->phase_seg1 - 1;
@@ -1483,6 +1502,23 @@ 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 = (priv->read_reg(priv, XCAN_SR_OFFSET) & XCAN_SR_TDCV_MASK) >>
+ XCAN_SR_TDCV_SHIFT;
+
+ return 0;
+}
+
static const struct net_device_ops xcan_netdev_ops = {
.ndo_open = xcan_open,
.ndo_stop = xcan_close,
@@ -1734,18 +1770,22 @@ static int xcan_probe(struct platform_device *pdev)
priv->can.do_get_berr_counter = xcan_get_berr_counter;
priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
CAN_CTRLMODE_BERR_REPORTING;
+ priv->can.do_get_auto_tdcv = xcan_get_auto_tdcv;
if (devtype->cantype == XAXI_CANFD)
priv->can.data_bittiming_const =
&xcan_data_bittiming_const_canfd;
- if (devtype->cantype == XAXI_CANFD_2_0)
+ if (devtype->cantype == XAXI_CANFD_2_0) {
priv->can.data_bittiming_const =
&xcan_data_bittiming_const_canfd2;
+ priv->can.tdc_const = &xcan_tdc_const;
+ }
if (devtype->cantype == XAXI_CANFD ||
devtype->cantype == XAXI_CANFD_2_0)
- priv->can.ctrlmode_supported |= CAN_CTRLMODE_FD;
+ priv->can.ctrlmode_supported |= CAN_CTRLMODE_FD |
+ CAN_CTRLMODE_TDC_AUTO;
priv->reg_base = addr;
priv->tx_max = tx_max;
--
2.25.1
