net/phy/linkmode.c

0001 // SPDX-License-Identifier: GPL-2.0+
0002 #include <linux/linkmode.h>
0003
0004 /**
0005  * linkmode_resolve_pause - resolve the allowable pause modes
0006  * @local_adv: local advertisement in ethtool format
0007  * @partner_adv: partner advertisement in ethtool format
0008  * @tx_pause: pointer to bool to indicate whether transmit pause should be
0009  * enabled.
0010  * @rx_pause: pointer to bool to indicate whether receive pause should be
0011  * enabled.
0012  *
0013  * Flow control is resolved according to our and the link partners
0014  * advertisements using the following drawn from the 802.3 specs:
0015  *  Local device  Link partner
0016  *  Pause AsymDir Pause AsymDir Result
0017  *    0     X       0     X     Disabled
0018  *    0     1       1     0     Disabled
0019  *    0     1       1     1     TX
0020  *    1     0       0     X     Disabled
0021  *    1     X       1     X     TX+RX
0022  *    1     1       0     1     RX
0023  */
0024 void linkmode_resolve_pause(const unsigned long *local_adv,
0025                 const unsigned long *partner_adv,
0026                 bool *tx_pause, bool *rx_pause)
0027 {
0028     __ETHTOOL_DECLARE_LINK_MODE_MASK(m);
0029
0030     linkmode_and(m, local_adv, partner_adv);
0031     if (linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT, m)) {
0032         *tx_pause = true;
0033         *rx_pause = true;
0034     } else if (linkmode_test_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT, m)) {
0035         *tx_pause = linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT,
0036                           partner_adv);
0037         *rx_pause = linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT,
0038                           local_adv);
0039     } else {
0040         *tx_pause = false;
0041         *rx_pause = false;
0042     }
0043 }
0044 EXPORT_SYMBOL_GPL(linkmode_resolve_pause);
0045
0046 /**
0047  * linkmode_set_pause - set the pause mode advertisement
0048  * @advertisement: advertisement in ethtool format
0049  * @tx: boolean from ethtool struct ethtool_pauseparam tx_pause member
0050  * @rx: boolean from ethtool struct ethtool_pauseparam rx_pause member
0051  *
0052  * Configure the advertised Pause and Asym_Pause bits according to the
0053  * capabilities of provided in @tx and @rx.
0054  *
0055  * We convert as follows:
0056  *  tx rx  Pause AsymDir
0057  *  0  0   0     0
0058  *  0  1   1     1
0059  *  1  0   0     1
0060  *  1  1   1     0
0061  *
0062  * Note: this translation from ethtool tx/rx notation to the advertisement
0063  * is actually very problematical. Here are some examples:
0064  *
0065  * For tx=0 rx=1, meaning transmit is unsupported, receive is supported:
0066  *
0067  *  Local device  Link partner
0068  *  Pause AsymDir Pause AsymDir Result
0069  *    1     1       1     0     TX + RX - but we have no TX support.
0070  *    1     1       0     1 Only this gives RX only
0071  *
0072  * For tx=1 rx=1, meaning we have the capability to transmit and receive
0073  * pause frames:
0074  *
0075  *  Local device  Link partner
0076  *  Pause AsymDir Pause AsymDir Result
0077  *    1     0       0     1     Disabled - but since we do support tx and rx,
0078  *              this should resolve to RX only.
0079  *
0080  * Hence, asking for:
0081  *  rx=1 tx=0 gives Pause+AsymDir advertisement, but we may end up
0082  *            resolving to tx+rx pause or only rx pause depending on
0083  *            the partners advertisement.
0084  *  rx=0 tx=1 gives AsymDir only, which will only give tx pause if
0085  *            the partners advertisement allows it.
0086  *  rx=1 tx=1 gives Pause only, which will only allow tx+rx pause
0087  *            if the other end also advertises Pause.
0088  */
0089 void linkmode_set_pause(unsigned long *advertisement, bool tx, bool rx)
0090 {
0091     linkmode_mod_bit(ETHTOOL_LINK_MODE_Pause_BIT, advertisement, rx);
0092     linkmode_mod_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT, advertisement,
0093              rx ^ tx);
0094 }
0095 EXPORT_SYMBOL_GPL(linkmode_set_pause);