drivers/net/phy/linkmode.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 #include <linux/linkmode.h>
   3
   4 /**
   5  * linkmode_resolve_pause - resolve the allowable pause modes
   6  * @local_adv: local advertisement in ethtool format
   7  * @partner_adv: partner advertisement in ethtool format
   8  * @tx_pause: pointer to bool to indicate whether transmit pause should be
   9  * enabled.
  10  * @rx_pause: pointer to bool to indicate whether receive pause should be
  11  * enabled.
  12  *
  13  * Flow control is resolved according to our and the link partners
  14  * advertisements using the following drawn from the 802.3 specs:
  15  *  Local device  Link partner
  16  *  Pause AsymDir Pause AsymDir Result
  17  *    0     X       0     X     Disabled
  18  *    0     1       1     0     Disabled
  19  *    0     1       1     1     TX
  20  *    1     0       0     X     Disabled
  21  *    1     X       1     X     TX+RX
  22  *    1     1       0     1     RX
  23  */
  24 void linkmode_resolve_pause(const unsigned long *local_adv,
  25                             const unsigned long *partner_adv,
  26                             bool *tx_pause, bool *rx_pause)
  27 {
  28         __ETHTOOL_DECLARE_LINK_MODE_MASK(m);
  29
  30         linkmode_and(m, local_adv, partner_adv);
  31         if (linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT, m)) {
  32                 *tx_pause = true;
  33                 *rx_pause = true;
  34         } else if (linkmode_test_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT, m)) {
  35                 *tx_pause = linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT,
  36                                               partner_adv);
  37                 *rx_pause = linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT,
  38                                               local_adv);
  39         } else {
  40                 *tx_pause = false;
  41                 *rx_pause = false;
  42         }
  43 }
  44 EXPORT_SYMBOL_GPL(linkmode_resolve_pause);
  45
  46 /**
  47  * linkmode_set_pause - set the pause mode advertisement
  48  * @advertisement: advertisement in ethtool format
  49  * @tx: boolean from ethtool struct ethtool_pauseparam tx_pause member
  50  * @rx: boolean from ethtool struct ethtool_pauseparam rx_pause member
  51  *
  52  * Configure the advertised Pause and Asym_Pause bits according to the
  53  * capabilities of provided in @tx and @rx.
  54  *
  55  * We convert as follows:
  56  *  tx rx  Pause AsymDir
  57  *  0  0   0     0
  58  *  0  1   1     1
  59  *  1  0   0     1
  60  *  1  1   1     0
  61  *
  62  * Note: this translation from ethtool tx/rx notation to the advertisement
  63  * is actually very problematical. Here are some examples:
  64  *
  65  * For tx=0 rx=1, meaning transmit is unsupported, receive is supported:
  66  *
  67  *  Local device  Link partner
  68  *  Pause AsymDir Pause AsymDir Result
  69  *    1     1       1     0     TX + RX - but we have no TX support.
  70  *    1     1       0     1     Only this gives RX only
  71  *
  72  * For tx=1 rx=1, meaning we have the capability to transmit and receive
  73  * pause frames:
  74  *
  75  *  Local device  Link partner
  76  *  Pause AsymDir Pause AsymDir Result
  77  *    1     0       0     1     Disabled - but since we do support tx and rx,
  78  *                              this should resolve to RX only.
  79  *
  80  * Hence, asking for:
  81  *  rx=1 tx=0 gives Pause+AsymDir advertisement, but we may end up
  82  *            resolving to tx+rx pause or only rx pause depending on
  83  *            the partners advertisement.
  84  *  rx=0 tx=1 gives AsymDir only, which will only give tx pause if
  85  *            the partners advertisement allows it.
  86  *  rx=1 tx=1 gives Pause only, which will only allow tx+rx pause
  87  *            if the other end also advertises Pause.
  88  */
  89 void linkmode_set_pause(unsigned long *advertisement, bool tx, bool rx)
  90 {
  91         linkmode_mod_bit(ETHTOOL_LINK_MODE_Pause_BIT, advertisement, rx);
  92         linkmode_mod_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT, advertisement,
  93                          rx ^ tx);
  94 }
  95 EXPORT_SYMBOL_GPL(linkmode_set_pause);