1
linux/drivers/net/cxgb3/xgmac.c
Divy Le Ray 59cf81076a cxgb3 - MAC watchdog update
The MAC watchdog was failing if the peer interface was brought down.

Signed-off-by: Divy Le Ray <divy@chelsio.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
2007-04-11 11:54:43 -04:00

565 lines
17 KiB
C

/*
* Copyright (c) 2005-2007 Chelsio, Inc. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the
* OpenIB.org BSD license below:
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "common.h"
#include "regs.h"
/*
* # of exact address filters. The first one is used for the station address,
* the rest are available for multicast addresses.
*/
#define EXACT_ADDR_FILTERS 8
static inline int macidx(const struct cmac *mac)
{
return mac->offset / (XGMAC0_1_BASE_ADDR - XGMAC0_0_BASE_ADDR);
}
static void xaui_serdes_reset(struct cmac *mac)
{
static const unsigned int clear[] = {
F_PWRDN0 | F_PWRDN1, F_RESETPLL01, F_RESET0 | F_RESET1,
F_PWRDN2 | F_PWRDN3, F_RESETPLL23, F_RESET2 | F_RESET3
};
int i;
struct adapter *adap = mac->adapter;
u32 ctrl = A_XGM_SERDES_CTRL0 + mac->offset;
t3_write_reg(adap, ctrl, adap->params.vpd.xauicfg[macidx(mac)] |
F_RESET3 | F_RESET2 | F_RESET1 | F_RESET0 |
F_PWRDN3 | F_PWRDN2 | F_PWRDN1 | F_PWRDN0 |
F_RESETPLL23 | F_RESETPLL01);
t3_read_reg(adap, ctrl);
udelay(15);
for (i = 0; i < ARRAY_SIZE(clear); i++) {
t3_set_reg_field(adap, ctrl, clear[i], 0);
udelay(15);
}
}
void t3b_pcs_reset(struct cmac *mac)
{
t3_set_reg_field(mac->adapter, A_XGM_RESET_CTRL + mac->offset,
F_PCS_RESET_, 0);
udelay(20);
t3_set_reg_field(mac->adapter, A_XGM_RESET_CTRL + mac->offset, 0,
F_PCS_RESET_);
}
int t3_mac_reset(struct cmac *mac)
{
static const struct addr_val_pair mac_reset_avp[] = {
{A_XGM_TX_CTRL, 0},
{A_XGM_RX_CTRL, 0},
{A_XGM_RX_CFG, F_DISPAUSEFRAMES | F_EN1536BFRAMES |
F_RMFCS | F_ENJUMBO | F_ENHASHMCAST},
{A_XGM_RX_HASH_LOW, 0},
{A_XGM_RX_HASH_HIGH, 0},
{A_XGM_RX_EXACT_MATCH_LOW_1, 0},
{A_XGM_RX_EXACT_MATCH_LOW_2, 0},
{A_XGM_RX_EXACT_MATCH_LOW_3, 0},
{A_XGM_RX_EXACT_MATCH_LOW_4, 0},
{A_XGM_RX_EXACT_MATCH_LOW_5, 0},
{A_XGM_RX_EXACT_MATCH_LOW_6, 0},
{A_XGM_RX_EXACT_MATCH_LOW_7, 0},
{A_XGM_RX_EXACT_MATCH_LOW_8, 0},
{A_XGM_STAT_CTRL, F_CLRSTATS}
};
u32 val;
struct adapter *adap = mac->adapter;
unsigned int oft = mac->offset;
t3_write_reg(adap, A_XGM_RESET_CTRL + oft, F_MAC_RESET_);
t3_read_reg(adap, A_XGM_RESET_CTRL + oft); /* flush */
t3_write_regs(adap, mac_reset_avp, ARRAY_SIZE(mac_reset_avp), oft);
t3_set_reg_field(adap, A_XGM_RXFIFO_CFG + oft,
F_RXSTRFRWRD | F_DISERRFRAMES,
uses_xaui(adap) ? 0 : F_RXSTRFRWRD);
if (uses_xaui(adap)) {
if (adap->params.rev == 0) {
t3_set_reg_field(adap, A_XGM_SERDES_CTRL + oft, 0,
F_RXENABLE | F_TXENABLE);
if (t3_wait_op_done(adap, A_XGM_SERDES_STATUS1 + oft,
F_CMULOCK, 1, 5, 2)) {
CH_ERR(adap,
"MAC %d XAUI SERDES CMU lock failed\n",
macidx(mac));
return -1;
}
t3_set_reg_field(adap, A_XGM_SERDES_CTRL + oft, 0,
F_SERDESRESET_);
} else
xaui_serdes_reset(mac);
}
val = F_MAC_RESET_;
if (is_10G(adap))
val |= F_PCS_RESET_;
else if (uses_xaui(adap))
val |= F_PCS_RESET_ | F_XG2G_RESET_;
else
val |= F_RGMII_RESET_ | F_XG2G_RESET_;
t3_write_reg(adap, A_XGM_RESET_CTRL + oft, val);
t3_read_reg(adap, A_XGM_RESET_CTRL + oft); /* flush */
if ((val & F_PCS_RESET_) && adap->params.rev) {
msleep(1);
t3b_pcs_reset(mac);
}
memset(&mac->stats, 0, sizeof(mac->stats));
return 0;
}
int t3b2_mac_reset(struct cmac *mac)
{
struct adapter *adap = mac->adapter;
unsigned int oft = mac->offset;
u32 val;
if (!macidx(mac))
t3_set_reg_field(adap, A_MPS_CFG, F_PORT0ACTIVE, 0);
else
t3_set_reg_field(adap, A_MPS_CFG, F_PORT1ACTIVE, 0);
t3_write_reg(adap, A_XGM_RESET_CTRL + oft, F_MAC_RESET_);
t3_read_reg(adap, A_XGM_RESET_CTRL + oft); /* flush */
msleep(10);
/* Check for xgm Rx fifo empty */
if (t3_wait_op_done(adap, A_XGM_RX_MAX_PKT_SIZE_ERR_CNT + oft,
0x80000000, 1, 5, 2)) {
CH_ERR(adap, "MAC %d Rx fifo drain failed\n",
macidx(mac));
return -1;
}
t3_write_reg(adap, A_XGM_RESET_CTRL + oft, 0);
t3_read_reg(adap, A_XGM_RESET_CTRL + oft); /* flush */
val = F_MAC_RESET_;
if (is_10G(adap))
val |= F_PCS_RESET_;
else if (uses_xaui(adap))
val |= F_PCS_RESET_ | F_XG2G_RESET_;
else
val |= F_RGMII_RESET_ | F_XG2G_RESET_;
t3_write_reg(adap, A_XGM_RESET_CTRL + oft, val);
t3_read_reg(adap, A_XGM_RESET_CTRL + oft); /* flush */
if ((val & F_PCS_RESET_) && adap->params.rev) {
msleep(1);
t3b_pcs_reset(mac);
}
t3_write_reg(adap, A_XGM_RX_CFG + oft,
F_DISPAUSEFRAMES | F_EN1536BFRAMES |
F_RMFCS | F_ENJUMBO | F_ENHASHMCAST);
if (!macidx(mac))
t3_set_reg_field(adap, A_MPS_CFG, 0, F_PORT0ACTIVE);
else
t3_set_reg_field(adap, A_MPS_CFG, 0, F_PORT1ACTIVE);
return 0;
}
/*
* Set the exact match register 'idx' to recognize the given Ethernet address.
*/
static void set_addr_filter(struct cmac *mac, int idx, const u8 * addr)
{
u32 addr_lo, addr_hi;
unsigned int oft = mac->offset + idx * 8;
addr_lo = (addr[3] << 24) | (addr[2] << 16) | (addr[1] << 8) | addr[0];
addr_hi = (addr[5] << 8) | addr[4];
t3_write_reg(mac->adapter, A_XGM_RX_EXACT_MATCH_LOW_1 + oft, addr_lo);
t3_write_reg(mac->adapter, A_XGM_RX_EXACT_MATCH_HIGH_1 + oft, addr_hi);
}
/* Set one of the station's unicast MAC addresses. */
int t3_mac_set_address(struct cmac *mac, unsigned int idx, u8 addr[6])
{
if (idx >= mac->nucast)
return -EINVAL;
set_addr_filter(mac, idx, addr);
return 0;
}
/*
* Specify the number of exact address filters that should be reserved for
* unicast addresses. Caller should reload the unicast and multicast addresses
* after calling this.
*/
int t3_mac_set_num_ucast(struct cmac *mac, int n)
{
if (n > EXACT_ADDR_FILTERS)
return -EINVAL;
mac->nucast = n;
return 0;
}
/* Calculate the RX hash filter index of an Ethernet address */
static int hash_hw_addr(const u8 * addr)
{
int hash = 0, octet, bit, i = 0, c;
for (octet = 0; octet < 6; ++octet)
for (c = addr[octet], bit = 0; bit < 8; c >>= 1, ++bit) {
hash ^= (c & 1) << i;
if (++i == 6)
i = 0;
}
return hash;
}
int t3_mac_set_rx_mode(struct cmac *mac, struct t3_rx_mode *rm)
{
u32 val, hash_lo, hash_hi;
struct adapter *adap = mac->adapter;
unsigned int oft = mac->offset;
val = t3_read_reg(adap, A_XGM_RX_CFG + oft) & ~F_COPYALLFRAMES;
if (rm->dev->flags & IFF_PROMISC)
val |= F_COPYALLFRAMES;
t3_write_reg(adap, A_XGM_RX_CFG + oft, val);
if (rm->dev->flags & IFF_ALLMULTI)
hash_lo = hash_hi = 0xffffffff;
else {
u8 *addr;
int exact_addr_idx = mac->nucast;
hash_lo = hash_hi = 0;
while ((addr = t3_get_next_mcaddr(rm)))
if (exact_addr_idx < EXACT_ADDR_FILTERS)
set_addr_filter(mac, exact_addr_idx++, addr);
else {
int hash = hash_hw_addr(addr);
if (hash < 32)
hash_lo |= (1 << hash);
else
hash_hi |= (1 << (hash - 32));
}
}
t3_write_reg(adap, A_XGM_RX_HASH_LOW + oft, hash_lo);
t3_write_reg(adap, A_XGM_RX_HASH_HIGH + oft, hash_hi);
return 0;
}
int t3_mac_set_mtu(struct cmac *mac, unsigned int mtu)
{
int hwm, lwm;
unsigned int thres, v;
struct adapter *adap = mac->adapter;
/*
* MAX_FRAME_SIZE inludes header + FCS, mtu doesn't. The HW max
* packet size register includes header, but not FCS.
*/
mtu += 14;
if (mtu > MAX_FRAME_SIZE - 4)
return -EINVAL;
t3_write_reg(adap, A_XGM_RX_MAX_PKT_SIZE + mac->offset, mtu);
/*
* Adjust the PAUSE frame watermarks. We always set the LWM, and the
* HWM only if flow-control is enabled.
*/
hwm = max_t(unsigned int, MAC_RXFIFO_SIZE - 3 * mtu,
MAC_RXFIFO_SIZE * 38 / 100);
hwm = min(hwm, MAC_RXFIFO_SIZE - 8192);
lwm = min(3 * (int)mtu, MAC_RXFIFO_SIZE / 4);
v = t3_read_reg(adap, A_XGM_RXFIFO_CFG + mac->offset);
v &= ~V_RXFIFOPAUSELWM(M_RXFIFOPAUSELWM);
v |= V_RXFIFOPAUSELWM(lwm / 8);
if (G_RXFIFOPAUSEHWM(v))
v = (v & ~V_RXFIFOPAUSEHWM(M_RXFIFOPAUSEHWM)) |
V_RXFIFOPAUSEHWM(hwm / 8);
t3_write_reg(adap, A_XGM_RXFIFO_CFG + mac->offset, v);
/* Adjust the TX FIFO threshold based on the MTU */
thres = (adap->params.vpd.cclk * 1000) / 15625;
thres = (thres * mtu) / 1000;
if (is_10G(adap))
thres /= 10;
thres = mtu > thres ? (mtu - thres + 7) / 8 : 0;
thres = max(thres, 8U); /* need at least 8 */
t3_set_reg_field(adap, A_XGM_TXFIFO_CFG + mac->offset,
V_TXFIFOTHRESH(M_TXFIFOTHRESH) | V_TXIPG(M_TXIPG),
V_TXFIFOTHRESH(thres) | V_TXIPG(1));
if (adap->params.rev > 0)
t3_write_reg(adap, A_XGM_PAUSE_TIMER + mac->offset,
(hwm - lwm) * 4 / 8);
t3_write_reg(adap, A_XGM_TX_PAUSE_QUANTA + mac->offset,
MAC_RXFIFO_SIZE * 4 * 8 / 512);
return 0;
}
int t3_mac_set_speed_duplex_fc(struct cmac *mac, int speed, int duplex, int fc)
{
u32 val;
struct adapter *adap = mac->adapter;
unsigned int oft = mac->offset;
if (duplex >= 0 && duplex != DUPLEX_FULL)
return -EINVAL;
if (speed >= 0) {
if (speed == SPEED_10)
val = V_PORTSPEED(0);
else if (speed == SPEED_100)
val = V_PORTSPEED(1);
else if (speed == SPEED_1000)
val = V_PORTSPEED(2);
else if (speed == SPEED_10000)
val = V_PORTSPEED(3);
else
return -EINVAL;
t3_set_reg_field(adap, A_XGM_PORT_CFG + oft,
V_PORTSPEED(M_PORTSPEED), val);
}
t3_set_reg_field(adap, A_XGM_TX_CFG + oft, F_TXPAUSEEN,
(fc & PAUSE_RX) ? F_TXPAUSEEN : 0);
return 0;
}
int t3_mac_enable(struct cmac *mac, int which)
{
int idx = macidx(mac);
struct adapter *adap = mac->adapter;
unsigned int oft = mac->offset;
struct mac_stats *s = &mac->stats;
if (which & MAC_DIRECTION_TX) {
t3_write_reg(adap, A_XGM_TX_CTRL + oft, F_TXEN);
t3_write_reg(adap, A_TP_PIO_ADDR, A_TP_TX_DROP_CFG_CH0 + idx);
t3_write_reg(adap, A_TP_PIO_DATA, 0xc0ede401);
t3_write_reg(adap, A_TP_PIO_ADDR, A_TP_TX_DROP_MODE);
t3_set_reg_field(adap, A_TP_PIO_DATA, 1 << idx, 1 << idx);
t3_write_reg(adap, A_TP_PIO_ADDR, A_TP_TX_DROP_CNT_CH0 + idx);
mac->tx_mcnt = s->tx_frames;
mac->tx_tcnt = (G_TXDROPCNTCH0RCVD(t3_read_reg(adap,
A_TP_PIO_DATA)));
mac->tx_xcnt = (G_TXSPI4SOPCNT(t3_read_reg(adap,
A_XGM_TX_SPI4_SOP_EOP_CNT +
oft)));
mac->rx_mcnt = s->rx_frames;
mac->rx_xcnt = (G_TXSPI4SOPCNT(t3_read_reg(adap,
A_XGM_RX_SPI4_SOP_EOP_CNT +
oft)));
mac->txen = F_TXEN;
mac->toggle_cnt = 0;
}
if (which & MAC_DIRECTION_RX)
t3_write_reg(adap, A_XGM_RX_CTRL + oft, F_RXEN);
return 0;
}
int t3_mac_disable(struct cmac *mac, int which)
{
int idx = macidx(mac);
struct adapter *adap = mac->adapter;
int val;
if (which & MAC_DIRECTION_TX) {
t3_write_reg(adap, A_XGM_TX_CTRL + mac->offset, 0);
t3_write_reg(adap, A_TP_PIO_ADDR, A_TP_TX_DROP_CFG_CH0 + idx);
t3_write_reg(adap, A_TP_PIO_DATA, 0xc000001f);
t3_write_reg(adap, A_TP_PIO_ADDR, A_TP_TX_DROP_MODE);
t3_set_reg_field(adap, A_TP_PIO_DATA, 1 << idx, 1 << idx);
mac->txen = 0;
}
if (which & MAC_DIRECTION_RX) {
t3_set_reg_field(mac->adapter, A_XGM_RESET_CTRL + mac->offset,
F_PCS_RESET_, 0);
msleep(100);
t3_write_reg(adap, A_XGM_RX_CTRL + mac->offset, 0);
val = F_MAC_RESET_;
if (is_10G(adap))
val |= F_PCS_RESET_;
else if (uses_xaui(adap))
val |= F_PCS_RESET_ | F_XG2G_RESET_;
else
val |= F_RGMII_RESET_ | F_XG2G_RESET_;
t3_write_reg(mac->adapter, A_XGM_RESET_CTRL + mac->offset, val);
}
return 0;
}
int t3b2_mac_watchdog_task(struct cmac *mac)
{
struct adapter *adap = mac->adapter;
struct mac_stats *s = &mac->stats;
unsigned int tx_tcnt, tx_xcnt;
unsigned int tx_mcnt = s->tx_frames;
unsigned int rx_mcnt = s->rx_frames;
unsigned int rx_xcnt;
int status;
if (tx_mcnt == mac->tx_mcnt) {
tx_xcnt = (G_TXSPI4SOPCNT(t3_read_reg(adap,
A_XGM_TX_SPI4_SOP_EOP_CNT +
mac->offset)));
if (tx_xcnt == 0) {
t3_write_reg(adap, A_TP_PIO_ADDR,
A_TP_TX_DROP_CNT_CH0 + macidx(mac));
tx_tcnt = (G_TXDROPCNTCH0RCVD(t3_read_reg(adap,
A_TP_PIO_DATA)));
} else {
mac->toggle_cnt = 0;
return 0;
}
} else {
mac->toggle_cnt = 0;
return 0;
}
if (((tx_tcnt != mac->tx_tcnt) &&
(tx_xcnt == 0) && (mac->tx_xcnt == 0)) ||
((mac->tx_mcnt == tx_mcnt) &&
(tx_xcnt != 0) && (mac->tx_xcnt != 0))) {
if (mac->toggle_cnt > 4)
status = 2;
else
status = 1;
} else {
mac->toggle_cnt = 0;
return 0;
}
if (rx_mcnt != mac->rx_mcnt)
rx_xcnt = (G_TXSPI4SOPCNT(t3_read_reg(adap,
A_XGM_RX_SPI4_SOP_EOP_CNT +
mac->offset)));
else
return 0;
if (mac->rx_mcnt != s->rx_frames && rx_xcnt == 0 && mac->rx_xcnt == 0)
status = 2;
mac->tx_tcnt = tx_tcnt;
mac->tx_xcnt = tx_xcnt;
mac->tx_mcnt = s->tx_frames;
mac->rx_xcnt = rx_xcnt;
mac->rx_mcnt = s->rx_frames;
if (status == 1) {
t3_write_reg(adap, A_XGM_TX_CTRL + mac->offset, 0);
t3_read_reg(adap, A_XGM_TX_CTRL + mac->offset); /* flush */
t3_write_reg(adap, A_XGM_TX_CTRL + mac->offset, mac->txen);
t3_read_reg(adap, A_XGM_TX_CTRL + mac->offset); /* flush */
mac->toggle_cnt++;
} else if (status == 2) {
t3b2_mac_reset(mac);
mac->toggle_cnt = 0;
}
return status;
}
/*
* This function is called periodically to accumulate the current values of the
* RMON counters into the port statistics. Since the packet counters are only
* 32 bits they can overflow in ~286 secs at 10G, so the function should be
* called more frequently than that. The byte counters are 45-bit wide, they
* would overflow in ~7.8 hours.
*/
const struct mac_stats *t3_mac_update_stats(struct cmac *mac)
{
#define RMON_READ(mac, addr) t3_read_reg(mac->adapter, addr + mac->offset)
#define RMON_UPDATE(mac, name, reg) \
(mac)->stats.name += (u64)RMON_READ(mac, A_XGM_STAT_##reg)
#define RMON_UPDATE64(mac, name, reg_lo, reg_hi) \
(mac)->stats.name += RMON_READ(mac, A_XGM_STAT_##reg_lo) + \
((u64)RMON_READ(mac, A_XGM_STAT_##reg_hi) << 32)
u32 v, lo;
RMON_UPDATE64(mac, rx_octets, RX_BYTES_LOW, RX_BYTES_HIGH);
RMON_UPDATE64(mac, rx_frames, RX_FRAMES_LOW, RX_FRAMES_HIGH);
RMON_UPDATE(mac, rx_mcast_frames, RX_MCAST_FRAMES);
RMON_UPDATE(mac, rx_bcast_frames, RX_BCAST_FRAMES);
RMON_UPDATE(mac, rx_fcs_errs, RX_CRC_ERR_FRAMES);
RMON_UPDATE(mac, rx_pause, RX_PAUSE_FRAMES);
RMON_UPDATE(mac, rx_jabber, RX_JABBER_FRAMES);
RMON_UPDATE(mac, rx_short, RX_SHORT_FRAMES);
RMON_UPDATE(mac, rx_symbol_errs, RX_SYM_CODE_ERR_FRAMES);
RMON_UPDATE(mac, rx_too_long, RX_OVERSIZE_FRAMES);
v = RMON_READ(mac, A_XGM_RX_MAX_PKT_SIZE_ERR_CNT);
if (mac->adapter->params.rev == T3_REV_B2)
v &= 0x7fffffff;
mac->stats.rx_too_long += v;
RMON_UPDATE(mac, rx_frames_64, RX_64B_FRAMES);
RMON_UPDATE(mac, rx_frames_65_127, RX_65_127B_FRAMES);
RMON_UPDATE(mac, rx_frames_128_255, RX_128_255B_FRAMES);
RMON_UPDATE(mac, rx_frames_256_511, RX_256_511B_FRAMES);
RMON_UPDATE(mac, rx_frames_512_1023, RX_512_1023B_FRAMES);
RMON_UPDATE(mac, rx_frames_1024_1518, RX_1024_1518B_FRAMES);
RMON_UPDATE(mac, rx_frames_1519_max, RX_1519_MAXB_FRAMES);
RMON_UPDATE64(mac, tx_octets, TX_BYTE_LOW, TX_BYTE_HIGH);
RMON_UPDATE64(mac, tx_frames, TX_FRAME_LOW, TX_FRAME_HIGH);
RMON_UPDATE(mac, tx_mcast_frames, TX_MCAST);
RMON_UPDATE(mac, tx_bcast_frames, TX_BCAST);
RMON_UPDATE(mac, tx_pause, TX_PAUSE);
/* This counts error frames in general (bad FCS, underrun, etc). */
RMON_UPDATE(mac, tx_underrun, TX_ERR_FRAMES);
RMON_UPDATE(mac, tx_frames_64, TX_64B_FRAMES);
RMON_UPDATE(mac, tx_frames_65_127, TX_65_127B_FRAMES);
RMON_UPDATE(mac, tx_frames_128_255, TX_128_255B_FRAMES);
RMON_UPDATE(mac, tx_frames_256_511, TX_256_511B_FRAMES);
RMON_UPDATE(mac, tx_frames_512_1023, TX_512_1023B_FRAMES);
RMON_UPDATE(mac, tx_frames_1024_1518, TX_1024_1518B_FRAMES);
RMON_UPDATE(mac, tx_frames_1519_max, TX_1519_MAXB_FRAMES);
/* The next stat isn't clear-on-read. */
t3_write_reg(mac->adapter, A_TP_MIB_INDEX, mac->offset ? 51 : 50);
v = t3_read_reg(mac->adapter, A_TP_MIB_RDATA);
lo = (u32) mac->stats.rx_cong_drops;
mac->stats.rx_cong_drops += (u64) (v - lo);
return &mac->stats;
}