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 */
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(dst: m, a: local_adv, b: 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 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 */
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