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1// SPDX-License-Identifier: GPL-2.0+2#include <linux/linkmode.h>3 4/**5 * linkmode_resolve_pause - resolve the allowable pause modes6 * @local_adv: local advertisement in ethtool format7 * @partner_adv: partner advertisement in ethtool format8 * @tx_pause: pointer to bool to indicate whether transmit pause should be9 * enabled.10 * @rx_pause: pointer to bool to indicate whether receive pause should be11 * enabled.12 *13 * Flow control is resolved according to our and the link partners14 * advertisements using the following drawn from the 802.3 specs:15 * Local device Link partner16 * Pause AsymDir Pause AsymDir Result17 * 0 X 0 X Disabled18 * 0 1 1 0 Disabled19 * 0 1 1 1 TX20 * 1 0 0 X Disabled21 * 1 X 1 X TX+RX22 * 1 1 0 1 RX23 */24void 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}44EXPORT_SYMBOL_GPL(linkmode_resolve_pause);45 46/**47 * linkmode_set_pause - set the pause mode advertisement48 * @advertisement: advertisement in ethtool format49 * @tx: boolean from ethtool struct ethtool_pauseparam tx_pause member50 * @rx: boolean from ethtool struct ethtool_pauseparam rx_pause member51 *52 * Configure the advertised Pause and Asym_Pause bits according to the53 * capabilities of provided in @tx and @rx.54 *55 * We convert as follows:56 * tx rx Pause AsymDir57 * 0 0 0 058 * 0 1 1 159 * 1 0 0 160 * 1 1 1 061 *62 * Note: this translation from ethtool tx/rx notation to the advertisement63 * 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 partner68 * Pause AsymDir Pause AsymDir Result69 * 1 1 1 0 TX + RX - but we have no TX support.70 * 1 1 0 1 Only this gives RX only71 *72 * For tx=1 rx=1, meaning we have the capability to transmit and receive73 * pause frames:74 *75 * Local device Link partner76 * Pause AsymDir Pause AsymDir Result77 * 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 up82 * resolving to tx+rx pause or only rx pause depending on83 * the partners advertisement.84 * rx=0 tx=1 gives AsymDir only, which will only give tx pause if85 * the partners advertisement allows it.86 * rx=1 tx=1 gives Pause only, which will only allow tx+rx pause87 * if the other end also advertises Pause.88 */89void 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}95EXPORT_SYMBOL_GPL(linkmode_set_pause);96