/* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
  * Copyright (C) 2006 Andrey Volkov, Varma Electronics
  * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
+ * Copyright (C) 2021 Vincent Mailhol <mailhol.vincent@wanadoo.fr>
  */
 
 #include <linux/can/dev.h>
        [IFLA_CAN_DATA_BITTIMING] = { .len = sizeof(struct can_bittiming) },
        [IFLA_CAN_DATA_BITTIMING_CONST] = { .len = sizeof(struct can_bittiming_const) },
        [IFLA_CAN_TERMINATION] = { .type = NLA_U16 },
+       [IFLA_CAN_TDC] = { .type = NLA_NESTED },
+};
+
+static const struct nla_policy can_tdc_policy[IFLA_CAN_TDC_MAX + 1] = {
+       [IFLA_CAN_TDC_TDCV_MIN] = { .type = NLA_U32 },
+       [IFLA_CAN_TDC_TDCV_MAX] = { .type = NLA_U32 },
+       [IFLA_CAN_TDC_TDCO_MIN] = { .type = NLA_U32 },
+       [IFLA_CAN_TDC_TDCO_MAX] = { .type = NLA_U32 },
+       [IFLA_CAN_TDC_TDCF_MIN] = { .type = NLA_U32 },
+       [IFLA_CAN_TDC_TDCF_MAX] = { .type = NLA_U32 },
+       [IFLA_CAN_TDC_TDCV] = { .type = NLA_U32 },
+       [IFLA_CAN_TDC_TDCO] = { .type = NLA_U32 },
+       [IFLA_CAN_TDC_TDCF] = { .type = NLA_U32 },
 };
 
 static int can_validate(struct nlattr *tb[], struct nlattr *data[],
         * - nominal/arbitration bittiming
         * - data bittiming
         * - control mode with CAN_CTRLMODE_FD set
+        * - TDC parameters are coherent (details below)
         */
 
        if (!data)
 
        if (data[IFLA_CAN_CTRLMODE]) {
                struct can_ctrlmode *cm = nla_data(data[IFLA_CAN_CTRLMODE]);
+               u32 tdc_flags = cm->flags & CAN_CTRLMODE_TDC_MASK;
 
                is_can_fd = cm->flags & cm->mask & CAN_CTRLMODE_FD;
+
+               /* CAN_CTRLMODE_TDC_{AUTO,MANUAL} are mutually exclusive */
+               if (tdc_flags == CAN_CTRLMODE_TDC_MASK)
+                       return -EOPNOTSUPP;
+               /* If one of the CAN_CTRLMODE_TDC_* flag is set then
+                * TDC must be set and vice-versa
+                */
+               if (!!tdc_flags != !!data[IFLA_CAN_TDC])
+                       return -EOPNOTSUPP;
+               /* If providing TDC parameters, at least TDCO is
+                * needed. TDCV is needed if and only if
+                * CAN_CTRLMODE_TDC_MANUAL is set
+                */
+               if (data[IFLA_CAN_TDC]) {
+                       struct nlattr *tb_tdc[IFLA_CAN_TDC_MAX + 1];
+                       int err;
+
+                       err = nla_parse_nested(tb_tdc, IFLA_CAN_TDC_MAX,
+                                              data[IFLA_CAN_TDC],
+                                              can_tdc_policy, extack);
+                       if (err)
+                               return err;
+
+                       if (tb_tdc[IFLA_CAN_TDC_TDCV]) {
+                               if (tdc_flags & CAN_CTRLMODE_TDC_AUTO)
+                                       return -EOPNOTSUPP;
+                       } else {
+                               if (tdc_flags & CAN_CTRLMODE_TDC_MANUAL)
+                                       return -EOPNOTSUPP;
+                       }
+
+                       if (!tb_tdc[IFLA_CAN_TDC_TDCO])
+                               return -EOPNOTSUPP;
+               }
        }
 
        if (is_can_fd) {
                        return -EOPNOTSUPP;
        }
 
-       if (data[IFLA_CAN_DATA_BITTIMING]) {
+       if (data[IFLA_CAN_DATA_BITTIMING] || data[IFLA_CAN_TDC]) {
                if (!is_can_fd)
                        return -EOPNOTSUPP;
        }
        return 0;
 }
 
+static int can_tdc_changelink(struct can_priv *priv, const struct nlattr *nla,
+                             struct netlink_ext_ack *extack)
+{
+       struct nlattr *tb_tdc[IFLA_CAN_TDC_MAX + 1];
+       struct can_tdc tdc = { 0 };
+       const struct can_tdc_const *tdc_const = priv->tdc_const;
+       int err;
+
+       if (!tdc_const || !can_tdc_is_enabled(priv))
+               return -EOPNOTSUPP;
+
+       err = nla_parse_nested(tb_tdc, IFLA_CAN_TDC_MAX, nla,
+                              can_tdc_policy, extack);
+       if (err)
+               return err;
+
+       if (tb_tdc[IFLA_CAN_TDC_TDCV]) {
+               u32 tdcv = nla_get_u32(tb_tdc[IFLA_CAN_TDC_TDCV]);
+
+               if (tdcv < tdc_const->tdcv_min || tdcv > tdc_const->tdcv_max)
+                       return -EINVAL;
+
+               tdc.tdcv = tdcv;
+       }
+
+       if (tb_tdc[IFLA_CAN_TDC_TDCO]) {
+               u32 tdco = nla_get_u32(tb_tdc[IFLA_CAN_TDC_TDCO]);
+
+               if (tdco < tdc_const->tdco_min || tdco > tdc_const->tdco_max)
+                       return -EINVAL;
+
+               tdc.tdco = tdco;
+       }
+
+       if (tb_tdc[IFLA_CAN_TDC_TDCF]) {
+               u32 tdcf = nla_get_u32(tb_tdc[IFLA_CAN_TDC_TDCF]);
+
+               if (tdcf < tdc_const->tdcf_min || tdcf > tdc_const->tdcf_max)
+                       return -EINVAL;
+
+               tdc.tdcf = tdcf;
+       }
+
+       priv->tdc = tdc;
+
+       return 0;
+}
+
 static int can_changelink(struct net_device *dev, struct nlattr *tb[],
                          struct nlattr *data[],
                          struct netlink_ext_ack *extack)
 {
        struct can_priv *priv = netdev_priv(dev);
+       u32 tdc_mask = 0;
        int err;
 
        /* We need synchronization with dev->stop() */
                        dev->mtu = CAN_MTU;
                        memset(&priv->data_bittiming, 0,
                               sizeof(priv->data_bittiming));
+                       priv->ctrlmode &= ~CAN_CTRLMODE_TDC_MASK;
+                       memset(&priv->tdc, 0, sizeof(priv->tdc));
                }
+
+               tdc_mask = cm->mask & CAN_CTRLMODE_TDC_MASK;
+               /* CAN_CTRLMODE_TDC_{AUTO,MANUAL} are mutually
+                * exclusive: make sure to turn the other one off
+                */
+               if (tdc_mask)
+                       priv->ctrlmode &= cm->flags | ~CAN_CTRLMODE_TDC_MASK;
        }
 
        if (data[IFLA_CAN_RESTART_MS]) {
                        return -EINVAL;
                }
 
-               memcpy(&priv->data_bittiming, &dbt, sizeof(dbt));
+               memset(&priv->tdc, 0, sizeof(priv->tdc));
+               if (data[IFLA_CAN_TDC]) {
+                       /* TDC parameters are provided: use them */
+                       err = can_tdc_changelink(priv, data[IFLA_CAN_TDC],
+                                                extack);
+                       if (err) {
+                               priv->ctrlmode &= ~CAN_CTRLMODE_TDC_MASK;
+                               return err;
+                       }
+               } else if (!tdc_mask) {
+                       /* Neither of TDC parameters nor TDC flags are
+                        * provided: do calculation
+                        */
+                       can_calc_tdco(&priv->tdc, priv->tdc_const, &priv->data_bittiming,
+                                     &priv->ctrlmode, priv->ctrlmode_supported);
+               } /* else: both CAN_CTRLMODE_TDC_{AUTO,MANUAL} are explicitly
+                  * turned off. TDC is disabled: do nothing
+                  */
 
-               can_calc_tdco(&priv->tdc, priv->tdc_const, &priv->data_bittiming,
-                             &priv->ctrlmode, priv->ctrlmode_supported);
+               memcpy(&priv->data_bittiming, &dbt, sizeof(dbt));
 
                if (priv->do_set_data_bittiming) {
                        /* Finally, set the bit-timing registers */
        return 0;
 }
 
+static size_t can_tdc_get_size(const struct net_device *dev)
+{
+       struct can_priv *priv = netdev_priv(dev);
+       size_t size;
+
+       if (!priv->tdc_const)
+               return 0;
+
+       size = nla_total_size(0);                       /* nest IFLA_CAN_TDC */
+       if (priv->ctrlmode_supported & CAN_CTRLMODE_TDC_MANUAL) {
+               size += nla_total_size(sizeof(u32));    /* IFLA_CAN_TDCV_MIN */
+               size += nla_total_size(sizeof(u32));    /* IFLA_CAN_TDCV_MAX */
+       }
+       size += nla_total_size(sizeof(u32));            /* IFLA_CAN_TDCO_MIN */
+       size += nla_total_size(sizeof(u32));            /* IFLA_CAN_TDCO_MAX */
+       if (priv->tdc_const->tdcf_max) {
+               size += nla_total_size(sizeof(u32));    /* IFLA_CAN_TDCF_MIN */
+               size += nla_total_size(sizeof(u32));    /* IFLA_CAN_TDCF_MAX */
+       }
+
+       if (can_tdc_is_enabled(priv)) {
+               if (priv->ctrlmode & CAN_CTRLMODE_TDC_MANUAL)
+                       size += nla_total_size(sizeof(u32));    /* IFLA_CAN_TDCV */
+               size += nla_total_size(sizeof(u32));            /* IFLA_CAN_TDCO */
+               if (priv->tdc_const->tdcf_max)
+                       size += nla_total_size(sizeof(u32));    /* IFLA_CAN_TDCF */
+       }
+
+       return size;
+}
+
 static size_t can_get_size(const struct net_device *dev)
 {
        struct can_priv *priv = netdev_priv(dev);
                size += nla_total_size(sizeof(*priv->data_bitrate_const) *
                                       priv->data_bitrate_const_cnt);
        size += sizeof(priv->bitrate_max);                      /* IFLA_CAN_BITRATE_MAX */
+       size += can_tdc_get_size(dev);                          /* IFLA_CAN_TDC */
 
        return size;
 }
 
+static int can_tdc_fill_info(struct sk_buff *skb, const struct net_device *dev)
+{
+       struct nlattr *nest;
+       struct can_priv *priv = netdev_priv(dev);
+       struct can_tdc *tdc = &priv->tdc;
+       const struct can_tdc_const *tdc_const = priv->tdc_const;
+
+       if (!tdc_const)
+               return 0;
+
+       nest = nla_nest_start(skb, IFLA_CAN_TDC);
+       if (!nest)
+               return -EMSGSIZE;
+
+       if (priv->ctrlmode_supported & CAN_CTRLMODE_TDC_MANUAL &&
+           (nla_put_u32(skb, IFLA_CAN_TDC_TDCV_MIN, tdc_const->tdcv_min) ||
+            nla_put_u32(skb, IFLA_CAN_TDC_TDCV_MAX, tdc_const->tdcv_max)))
+               goto err_cancel;
+       if (nla_put_u32(skb, IFLA_CAN_TDC_TDCO_MIN, tdc_const->tdco_min) ||
+           nla_put_u32(skb, IFLA_CAN_TDC_TDCO_MAX, tdc_const->tdco_max))
+               goto err_cancel;
+       if (tdc_const->tdcf_max &&
+           (nla_put_u32(skb, IFLA_CAN_TDC_TDCF_MIN, tdc_const->tdcf_min) ||
+            nla_put_u32(skb, IFLA_CAN_TDC_TDCF_MAX, tdc_const->tdcf_max)))
+               goto err_cancel;
+
+       if (can_tdc_is_enabled(priv)) {
+               if (priv->ctrlmode & CAN_CTRLMODE_TDC_MANUAL &&
+                   nla_put_u32(skb, IFLA_CAN_TDC_TDCV, tdc->tdcv))
+                       goto err_cancel;
+               if (nla_put_u32(skb, IFLA_CAN_TDC_TDCO, tdc->tdco))
+                       goto err_cancel;
+               if (tdc_const->tdcf_max &&
+                   nla_put_u32(skb, IFLA_CAN_TDC_TDCF, tdc->tdcf))
+                       goto err_cancel;
+       }
+
+       nla_nest_end(skb, nest);
+       return 0;
+
+err_cancel:
+       nla_nest_cancel(skb, nest);
+       return -EMSGSIZE;
+}
+
 static int can_fill_info(struct sk_buff *skb, const struct net_device *dev)
 {
        struct can_priv *priv = netdev_priv(dev);
 
            (nla_put(skb, IFLA_CAN_BITRATE_MAX,
                     sizeof(priv->bitrate_max),
-                    &priv->bitrate_max))
+                    &priv->bitrate_max)) ||
+
+           (can_tdc_fill_info(skb, dev))
            )
 
                return -EMSGSIZE;