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Add a linkmode helper to set the flow control advertisement in an ethtool linkmode mask according to the tx/rx capabilities. This implementation is moved from phylib, and documented with an analysis of its shortcomings. Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
95 lines
3.3 KiB
C
95 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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#include <linux/linkmode.h>
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/**
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* linkmode_resolve_pause - resolve the allowable pause modes
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* @local_adv: local advertisement in ethtool format
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* @partner_adv: partner advertisement in ethtool format
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* @tx_pause: pointer to bool to indicate whether transmit pause should be
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* enabled.
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* @rx_pause: pointer to bool to indicate whether receive pause should be
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* enabled.
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*
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* Flow control is resolved according to our and the link partners
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* advertisements using the following drawn from the 802.3 specs:
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* Local device Link partner
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* Pause AsymDir Pause AsymDir Result
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* 0 X 0 X Disabled
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* 0 1 1 0 Disabled
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* 0 1 1 1 TX
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* 1 0 0 X Disabled
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* 1 X 1 X TX+RX
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* 1 1 0 1 RX
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*/
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void linkmode_resolve_pause(const unsigned long *local_adv,
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const unsigned long *partner_adv,
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bool *tx_pause, bool *rx_pause)
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{
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__ETHTOOL_DECLARE_LINK_MODE_MASK(m);
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linkmode_and(m, local_adv, partner_adv);
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if (linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT, m)) {
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*tx_pause = true;
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*rx_pause = true;
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} else if (linkmode_test_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT, m)) {
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*tx_pause = linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT,
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partner_adv);
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*rx_pause = linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT,
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local_adv);
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} else {
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*tx_pause = false;
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*rx_pause = false;
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}
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}
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EXPORT_SYMBOL_GPL(linkmode_resolve_pause);
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/**
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* linkmode_set_pause - set the pause mode advertisement
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* @advertisement: advertisement in ethtool format
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* @tx: boolean from ethtool struct ethtool_pauseparam tx_pause member
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* @rx: boolean from ethtool struct ethtool_pauseparam rx_pause member
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*
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* Configure the advertised Pause and Asym_Pause bits according to the
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* capabilities of provided in @tx and @rx.
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*
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* We convert as follows:
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* tx rx Pause AsymDir
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* 0 0 0 0
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* 0 1 1 1
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* 1 0 0 1
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* 1 1 1 0
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*
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* Note: this translation from ethtool tx/rx notation to the advertisement
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* is actually very problematical. Here are some examples:
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*
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* For tx=0 rx=1, meaning transmit is unsupported, receive is supported:
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*
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* Local device Link partner
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* Pause AsymDir Pause AsymDir Result
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* 1 1 1 0 TX + RX - but we have no TX support.
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* 1 1 0 1 Only this gives RX only
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*
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* For tx=1 rx=1, meaning we have the capability to transmit and receive
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* pause frames:
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*
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* Local device Link partner
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* Pause AsymDir Pause AsymDir Result
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* 1 0 0 1 Disabled - but since we do support tx and rx,
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* this should resolve to RX only.
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*
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* Hence, asking for:
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* rx=1 tx=0 gives Pause+AsymDir advertisement, but we may end up
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* resolving to tx+rx pause or only rx pause depending on
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* the partners advertisement.
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* rx=0 tx=1 gives AsymDir only, which will only give tx pause if
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* the partners advertisement allows it.
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* rx=1 tx=1 gives Pause only, which will only allow tx+rx pause
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* if the other end also advertises Pause.
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*/
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void linkmode_set_pause(unsigned long *advertisement, bool tx, bool rx)
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{
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linkmode_mod_bit(ETHTOOL_LINK_MODE_Pause_BIT, advertisement, rx);
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linkmode_mod_bit(ETHTOOL_LINK_MODE_Asym_Pause_BIT, advertisement,
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rx ^ tx);
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}
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EXPORT_SYMBOL_GPL(linkmode_set_pause);
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