linux/drivers/net/wireless/b43legacy/xmit.c
Stefano Brivio 9eca9a8e81 b43legacy: drop packets we are not able to encrypt
We must drop any packets we are not able to encrypt.
We must not send them unencrypted or with an all-zero-key (which
basically is the same as unencrypted, from a security point of view).

This might only trigger shortly after resume before mac80211 reassociated
and reconfigured the keys.

It is safe to drop these packets, as the association they belong to
is not guaranteed anymore anyway.
This is a security fix in the sense that it prevents information leakage.

This patch by Michael Buesch has been ported to b43legacy.

Cc: Michael Buesch <mb@bu3sch.de>
Signed-off-by: Stefano Brivio <stefano.brivio@polimi.it>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2008-02-05 14:35:46 -05:00

670 lines
18 KiB
C

/*
Broadcom B43legacy wireless driver
Transmission (TX/RX) related functions.
Copyright (C) 2005 Martin Langer <martin-langer@gmx.de>
Copyright (C) 2005 Stefano Brivio <stefano.brivio@polimi.it>
Copyright (C) 2005, 2006 Michael Buesch <mb@bu3sch.de>
Copyright (C) 2005 Danny van Dyk <kugelfang@gentoo.org>
Copyright (C) 2005 Andreas Jaggi <andreas.jaggi@waterwave.ch>
Copyright (C) 2007 Larry Finger <Larry.Finger@lwfinger.net>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; see the file COPYING. If not, write to
the Free Software Foundation, Inc., 51 Franklin Steet, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#include <net/dst.h>
#include "xmit.h"
#include "phy.h"
#include "dma.h"
#include "pio.h"
/* Extract the bitrate out of a CCK PLCP header. */
static u8 b43legacy_plcp_get_bitrate_cck(struct b43legacy_plcp_hdr6 *plcp)
{
switch (plcp->raw[0]) {
case 0x0A:
return B43legacy_CCK_RATE_1MB;
case 0x14:
return B43legacy_CCK_RATE_2MB;
case 0x37:
return B43legacy_CCK_RATE_5MB;
case 0x6E:
return B43legacy_CCK_RATE_11MB;
}
B43legacy_BUG_ON(1);
return 0;
}
/* Extract the bitrate out of an OFDM PLCP header. */
static u8 b43legacy_plcp_get_bitrate_ofdm(struct b43legacy_plcp_hdr6 *plcp)
{
switch (plcp->raw[0] & 0xF) {
case 0xB:
return B43legacy_OFDM_RATE_6MB;
case 0xF:
return B43legacy_OFDM_RATE_9MB;
case 0xA:
return B43legacy_OFDM_RATE_12MB;
case 0xE:
return B43legacy_OFDM_RATE_18MB;
case 0x9:
return B43legacy_OFDM_RATE_24MB;
case 0xD:
return B43legacy_OFDM_RATE_36MB;
case 0x8:
return B43legacy_OFDM_RATE_48MB;
case 0xC:
return B43legacy_OFDM_RATE_54MB;
}
B43legacy_BUG_ON(1);
return 0;
}
u8 b43legacy_plcp_get_ratecode_cck(const u8 bitrate)
{
switch (bitrate) {
case B43legacy_CCK_RATE_1MB:
return 0x0A;
case B43legacy_CCK_RATE_2MB:
return 0x14;
case B43legacy_CCK_RATE_5MB:
return 0x37;
case B43legacy_CCK_RATE_11MB:
return 0x6E;
}
B43legacy_BUG_ON(1);
return 0;
}
u8 b43legacy_plcp_get_ratecode_ofdm(const u8 bitrate)
{
switch (bitrate) {
case B43legacy_OFDM_RATE_6MB:
return 0xB;
case B43legacy_OFDM_RATE_9MB:
return 0xF;
case B43legacy_OFDM_RATE_12MB:
return 0xA;
case B43legacy_OFDM_RATE_18MB:
return 0xE;
case B43legacy_OFDM_RATE_24MB:
return 0x9;
case B43legacy_OFDM_RATE_36MB:
return 0xD;
case B43legacy_OFDM_RATE_48MB:
return 0x8;
case B43legacy_OFDM_RATE_54MB:
return 0xC;
}
B43legacy_BUG_ON(1);
return 0;
}
void b43legacy_generate_plcp_hdr(struct b43legacy_plcp_hdr4 *plcp,
const u16 octets, const u8 bitrate)
{
__le32 *data = &(plcp->data);
__u8 *raw = plcp->raw;
if (b43legacy_is_ofdm_rate(bitrate)) {
u16 d;
d = b43legacy_plcp_get_ratecode_ofdm(bitrate);
B43legacy_WARN_ON(octets & 0xF000);
d |= (octets << 5);
*data = cpu_to_le32(d);
} else {
u32 plen;
plen = octets * 16 / bitrate;
if ((octets * 16 % bitrate) > 0) {
plen++;
if ((bitrate == B43legacy_CCK_RATE_11MB)
&& ((octets * 8 % 11) < 4))
raw[1] = 0x84;
else
raw[1] = 0x04;
} else
raw[1] = 0x04;
*data |= cpu_to_le32(plen << 16);
raw[0] = b43legacy_plcp_get_ratecode_cck(bitrate);
}
}
static u8 b43legacy_calc_fallback_rate(u8 bitrate)
{
switch (bitrate) {
case B43legacy_CCK_RATE_1MB:
return B43legacy_CCK_RATE_1MB;
case B43legacy_CCK_RATE_2MB:
return B43legacy_CCK_RATE_1MB;
case B43legacy_CCK_RATE_5MB:
return B43legacy_CCK_RATE_2MB;
case B43legacy_CCK_RATE_11MB:
return B43legacy_CCK_RATE_5MB;
case B43legacy_OFDM_RATE_6MB:
return B43legacy_CCK_RATE_5MB;
case B43legacy_OFDM_RATE_9MB:
return B43legacy_OFDM_RATE_6MB;
case B43legacy_OFDM_RATE_12MB:
return B43legacy_OFDM_RATE_9MB;
case B43legacy_OFDM_RATE_18MB:
return B43legacy_OFDM_RATE_12MB;
case B43legacy_OFDM_RATE_24MB:
return B43legacy_OFDM_RATE_18MB;
case B43legacy_OFDM_RATE_36MB:
return B43legacy_OFDM_RATE_24MB;
case B43legacy_OFDM_RATE_48MB:
return B43legacy_OFDM_RATE_36MB;
case B43legacy_OFDM_RATE_54MB:
return B43legacy_OFDM_RATE_48MB;
}
B43legacy_BUG_ON(1);
return 0;
}
static int generate_txhdr_fw3(struct b43legacy_wldev *dev,
struct b43legacy_txhdr_fw3 *txhdr,
const unsigned char *fragment_data,
unsigned int fragment_len,
const struct ieee80211_tx_control *txctl,
u16 cookie)
{
const struct ieee80211_hdr *wlhdr;
int use_encryption = (!(txctl->flags & IEEE80211_TXCTL_DO_NOT_ENCRYPT));
u16 fctl;
u8 rate;
u8 rate_fb;
int rate_ofdm;
int rate_fb_ofdm;
unsigned int plcp_fragment_len;
u32 mac_ctl = 0;
u16 phy_ctl = 0;
wlhdr = (const struct ieee80211_hdr *)fragment_data;
fctl = le16_to_cpu(wlhdr->frame_control);
memset(txhdr, 0, sizeof(*txhdr));
rate = txctl->tx_rate;
rate_ofdm = b43legacy_is_ofdm_rate(rate);
rate_fb = (txctl->alt_retry_rate == -1) ? rate : txctl->alt_retry_rate;
rate_fb_ofdm = b43legacy_is_ofdm_rate(rate_fb);
txhdr->mac_frame_ctl = wlhdr->frame_control;
memcpy(txhdr->tx_receiver, wlhdr->addr1, 6);
/* Calculate duration for fallback rate */
if ((rate_fb == rate) ||
(wlhdr->duration_id & cpu_to_le16(0x8000)) ||
(wlhdr->duration_id == cpu_to_le16(0))) {
/* If the fallback rate equals the normal rate or the
* dur_id field contains an AID, CFP magic or 0,
* use the original dur_id field. */
txhdr->dur_fb = wlhdr->duration_id;
} else {
int fbrate_base100kbps = B43legacy_RATE_TO_100KBPS(rate_fb);
txhdr->dur_fb = ieee80211_generic_frame_duration(dev->wl->hw,
txctl->vif,
fragment_len,
fbrate_base100kbps);
}
plcp_fragment_len = fragment_len + FCS_LEN;
if (use_encryption) {
u8 key_idx = (u16)(txctl->key_idx);
struct b43legacy_key *key;
int wlhdr_len;
size_t iv_len;
B43legacy_WARN_ON(key_idx >= dev->max_nr_keys);
key = &(dev->key[key_idx]);
if (key->enabled) {
/* Hardware appends ICV. */
plcp_fragment_len += txctl->icv_len;
key_idx = b43legacy_kidx_to_fw(dev, key_idx);
mac_ctl |= (key_idx << B43legacy_TX4_MAC_KEYIDX_SHIFT) &
B43legacy_TX4_MAC_KEYIDX;
mac_ctl |= (key->algorithm <<
B43legacy_TX4_MAC_KEYALG_SHIFT) &
B43legacy_TX4_MAC_KEYALG;
wlhdr_len = ieee80211_get_hdrlen(fctl);
iv_len = min((size_t)txctl->iv_len,
ARRAY_SIZE(txhdr->iv));
memcpy(txhdr->iv, ((u8 *)wlhdr) + wlhdr_len, iv_len);
} else {
/* This key is invalid. This might only happen
* in a short timeframe after machine resume before
* we were able to reconfigure keys.
* Drop this packet completely. Do not transmit it
* unencrypted to avoid leaking information. */
return -ENOKEY;
}
}
b43legacy_generate_plcp_hdr((struct b43legacy_plcp_hdr4 *)
(&txhdr->plcp), plcp_fragment_len,
rate);
b43legacy_generate_plcp_hdr((struct b43legacy_plcp_hdr4 *)
(&txhdr->plcp_fb), plcp_fragment_len,
rate_fb);
/* PHY TX Control word */
if (rate_ofdm)
phy_ctl |= B43legacy_TX4_PHY_OFDM;
if (dev->short_preamble)
phy_ctl |= B43legacy_TX4_PHY_SHORTPRMBL;
switch (txctl->antenna_sel_tx) {
case 0:
phy_ctl |= B43legacy_TX4_PHY_ANTLAST;
break;
case 1:
phy_ctl |= B43legacy_TX4_PHY_ANT0;
break;
case 2:
phy_ctl |= B43legacy_TX4_PHY_ANT1;
break;
default:
B43legacy_BUG_ON(1);
}
/* MAC control */
if (!(txctl->flags & IEEE80211_TXCTL_NO_ACK))
mac_ctl |= B43legacy_TX4_MAC_ACK;
if (!(((fctl & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_CTL) &&
((fctl & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_PSPOLL)))
mac_ctl |= B43legacy_TX4_MAC_HWSEQ;
if (txctl->flags & IEEE80211_TXCTL_FIRST_FRAGMENT)
mac_ctl |= B43legacy_TX4_MAC_STMSDU;
if (rate_fb_ofdm)
mac_ctl |= B43legacy_TX4_MAC_FALLBACKOFDM;
if (txctl->flags & IEEE80211_TXCTL_LONG_RETRY_LIMIT)
mac_ctl |= B43legacy_TX4_MAC_LONGFRAME;
/* Generate the RTS or CTS-to-self frame */
if ((txctl->flags & IEEE80211_TXCTL_USE_RTS_CTS) ||
(txctl->flags & IEEE80211_TXCTL_USE_CTS_PROTECT)) {
unsigned int len;
struct ieee80211_hdr *hdr;
int rts_rate;
int rts_rate_fb;
int rts_rate_ofdm;
int rts_rate_fb_ofdm;
rts_rate = txctl->rts_cts_rate;
rts_rate_ofdm = b43legacy_is_ofdm_rate(rts_rate);
rts_rate_fb = b43legacy_calc_fallback_rate(rts_rate);
rts_rate_fb_ofdm = b43legacy_is_ofdm_rate(rts_rate_fb);
if (rts_rate_fb_ofdm)
mac_ctl |= B43legacy_TX4_MAC_CTSFALLBACKOFDM;
if (txctl->flags & IEEE80211_TXCTL_USE_CTS_PROTECT) {
ieee80211_ctstoself_get(dev->wl->hw,
txctl->vif,
fragment_data,
fragment_len, txctl,
(struct ieee80211_cts *)
(txhdr->rts_frame));
mac_ctl |= B43legacy_TX4_MAC_SENDCTS;
len = sizeof(struct ieee80211_cts);
} else {
ieee80211_rts_get(dev->wl->hw,
txctl->vif,
fragment_data, fragment_len, txctl,
(struct ieee80211_rts *)
(txhdr->rts_frame));
mac_ctl |= B43legacy_TX4_MAC_SENDRTS;
len = sizeof(struct ieee80211_rts);
}
len += FCS_LEN;
b43legacy_generate_plcp_hdr((struct b43legacy_plcp_hdr4 *)
(&txhdr->rts_plcp),
len, rts_rate);
b43legacy_generate_plcp_hdr((struct b43legacy_plcp_hdr4 *)
(&txhdr->rts_plcp_fb),
len, rts_rate_fb);
hdr = (struct ieee80211_hdr *)(&txhdr->rts_frame);
txhdr->rts_dur_fb = hdr->duration_id;
}
/* Magic cookie */
txhdr->cookie = cpu_to_le16(cookie);
/* Apply the bitfields */
txhdr->mac_ctl = cpu_to_le32(mac_ctl);
txhdr->phy_ctl = cpu_to_le16(phy_ctl);
return 0;
}
int b43legacy_generate_txhdr(struct b43legacy_wldev *dev,
u8 *txhdr,
const unsigned char *fragment_data,
unsigned int fragment_len,
const struct ieee80211_tx_control *txctl,
u16 cookie)
{
return generate_txhdr_fw3(dev, (struct b43legacy_txhdr_fw3 *)txhdr,
fragment_data, fragment_len,
txctl, cookie);
}
static s8 b43legacy_rssi_postprocess(struct b43legacy_wldev *dev,
u8 in_rssi, int ofdm,
int adjust_2053, int adjust_2050)
{
struct b43legacy_phy *phy = &dev->phy;
s32 tmp;
switch (phy->radio_ver) {
case 0x2050:
if (ofdm) {
tmp = in_rssi;
if (tmp > 127)
tmp -= 256;
tmp *= 73;
tmp /= 64;
if (adjust_2050)
tmp += 25;
else
tmp -= 3;
} else {
if (dev->dev->bus->sprom.boardflags_lo
& B43legacy_BFL_RSSI) {
if (in_rssi > 63)
in_rssi = 63;
tmp = phy->nrssi_lt[in_rssi];
tmp = 31 - tmp;
tmp *= -131;
tmp /= 128;
tmp -= 57;
} else {
tmp = in_rssi;
tmp = 31 - tmp;
tmp *= -149;
tmp /= 128;
tmp -= 68;
}
if (phy->type == B43legacy_PHYTYPE_G &&
adjust_2050)
tmp += 25;
}
break;
case 0x2060:
if (in_rssi > 127)
tmp = in_rssi - 256;
else
tmp = in_rssi;
break;
default:
tmp = in_rssi;
tmp -= 11;
tmp *= 103;
tmp /= 64;
if (adjust_2053)
tmp -= 109;
else
tmp -= 83;
}
return (s8)tmp;
}
void b43legacy_rx(struct b43legacy_wldev *dev,
struct sk_buff *skb,
const void *_rxhdr)
{
struct ieee80211_rx_status status;
struct b43legacy_plcp_hdr6 *plcp;
struct ieee80211_hdr *wlhdr;
const struct b43legacy_rxhdr_fw3 *rxhdr = _rxhdr;
u16 fctl;
u16 phystat0;
u16 phystat3;
u16 chanstat;
u16 mactime;
u32 macstat;
u16 chanid;
u8 jssi;
int padding;
memset(&status, 0, sizeof(status));
/* Get metadata about the frame from the header. */
phystat0 = le16_to_cpu(rxhdr->phy_status0);
phystat3 = le16_to_cpu(rxhdr->phy_status3);
jssi = rxhdr->jssi;
macstat = le16_to_cpu(rxhdr->mac_status);
mactime = le16_to_cpu(rxhdr->mac_time);
chanstat = le16_to_cpu(rxhdr->channel);
if (macstat & B43legacy_RX_MAC_FCSERR)
dev->wl->ieee_stats.dot11FCSErrorCount++;
/* Skip PLCP and padding */
padding = (macstat & B43legacy_RX_MAC_PADDING) ? 2 : 0;
if (unlikely(skb->len < (sizeof(struct b43legacy_plcp_hdr6) +
padding))) {
b43legacydbg(dev->wl, "RX: Packet size underrun (1)\n");
goto drop;
}
plcp = (struct b43legacy_plcp_hdr6 *)(skb->data + padding);
skb_pull(skb, sizeof(struct b43legacy_plcp_hdr6) + padding);
/* The skb contains the Wireless Header + payload data now */
if (unlikely(skb->len < (2+2+6/*minimum hdr*/ + FCS_LEN))) {
b43legacydbg(dev->wl, "RX: Packet size underrun (2)\n");
goto drop;
}
wlhdr = (struct ieee80211_hdr *)(skb->data);
fctl = le16_to_cpu(wlhdr->frame_control);
if ((macstat & B43legacy_RX_MAC_DEC) &&
!(macstat & B43legacy_RX_MAC_DECERR)) {
unsigned int keyidx;
int wlhdr_len;
int iv_len;
int icv_len;
keyidx = ((macstat & B43legacy_RX_MAC_KEYIDX)
>> B43legacy_RX_MAC_KEYIDX_SHIFT);
/* We must adjust the key index here. We want the "physical"
* key index, but the ucode passed it slightly different.
*/
keyidx = b43legacy_kidx_to_raw(dev, keyidx);
B43legacy_WARN_ON(keyidx >= dev->max_nr_keys);
if (dev->key[keyidx].algorithm != B43legacy_SEC_ALGO_NONE) {
/* Remove PROTECTED flag to mark it as decrypted. */
B43legacy_WARN_ON(!(fctl & IEEE80211_FCTL_PROTECTED));
fctl &= ~IEEE80211_FCTL_PROTECTED;
wlhdr->frame_control = cpu_to_le16(fctl);
wlhdr_len = ieee80211_get_hdrlen(fctl);
if (unlikely(skb->len < (wlhdr_len + 3))) {
b43legacydbg(dev->wl, "RX: Packet size"
" underrun3\n");
goto drop;
}
if (skb->data[wlhdr_len + 3] & (1 << 5)) {
/* The Ext-IV Bit is set in the "KeyID"
* octet of the IV.
*/
iv_len = 8;
icv_len = 8;
} else {
iv_len = 4;
icv_len = 4;
}
if (unlikely(skb->len < (wlhdr_len + iv_len +
icv_len))) {
b43legacydbg(dev->wl, "RX: Packet size"
" underrun4\n");
goto drop;
}
/* Remove the IV */
memmove(skb->data + iv_len, skb->data, wlhdr_len);
skb_pull(skb, iv_len);
/* Remove the ICV */
skb_trim(skb, skb->len - icv_len);
status.flag |= RX_FLAG_DECRYPTED;
}
}
status.ssi = b43legacy_rssi_postprocess(dev, jssi,
(phystat0 & B43legacy_RX_PHYST0_OFDM),
(phystat0 & B43legacy_RX_PHYST0_GAINCTL),
(phystat3 & B43legacy_RX_PHYST3_TRSTATE));
status.noise = dev->stats.link_noise;
status.signal = (jssi * 100) / B43legacy_RX_MAX_SSI;
if (phystat0 & B43legacy_RX_PHYST0_OFDM)
status.rate = b43legacy_plcp_get_bitrate_ofdm(plcp);
else
status.rate = b43legacy_plcp_get_bitrate_cck(plcp);
status.antenna = !!(phystat0 & B43legacy_RX_PHYST0_ANT);
/*
* If monitors are present get full 64-bit timestamp. This
* code assumes we get to process the packet within 16 bits
* of timestamp, i.e. about 65 milliseconds after the PHY
* received the first symbol.
*/
if (dev->wl->radiotap_enabled) {
u16 low_mactime_now;
b43legacy_tsf_read(dev, &status.mactime);
low_mactime_now = status.mactime;
status.mactime = status.mactime & ~0xFFFFULL;
status.mactime += mactime;
if (low_mactime_now <= mactime)
status.mactime -= 0x10000;
status.flag |= RX_FLAG_TSFT;
}
chanid = (chanstat & B43legacy_RX_CHAN_ID) >>
B43legacy_RX_CHAN_ID_SHIFT;
switch (chanstat & B43legacy_RX_CHAN_PHYTYPE) {
case B43legacy_PHYTYPE_B:
status.phymode = MODE_IEEE80211B;
status.freq = chanid + 2400;
status.channel = b43legacy_freq_to_channel_bg(chanid + 2400);
break;
case B43legacy_PHYTYPE_G:
status.phymode = MODE_IEEE80211G;
status.freq = chanid + 2400;
status.channel = b43legacy_freq_to_channel_bg(chanid + 2400);
break;
default:
b43legacywarn(dev->wl, "Unexpected value for chanstat (0x%X)\n",
chanstat);
}
dev->stats.last_rx = jiffies;
ieee80211_rx_irqsafe(dev->wl->hw, skb, &status);
return;
drop:
b43legacydbg(dev->wl, "RX: Packet dropped\n");
dev_kfree_skb_any(skb);
}
void b43legacy_handle_txstatus(struct b43legacy_wldev *dev,
const struct b43legacy_txstatus *status)
{
b43legacy_debugfs_log_txstat(dev, status);
if (status->intermediate)
return;
if (status->for_ampdu)
return;
if (!status->acked)
dev->wl->ieee_stats.dot11ACKFailureCount++;
if (status->rts_count) {
if (status->rts_count == 0xF) /* FIXME */
dev->wl->ieee_stats.dot11RTSFailureCount++;
else
dev->wl->ieee_stats.dot11RTSSuccessCount++;
}
if (b43legacy_using_pio(dev))
b43legacy_pio_handle_txstatus(dev, status);
else
b43legacy_dma_handle_txstatus(dev, status);
}
/* Handle TX status report as received through DMA/PIO queues */
void b43legacy_handle_hwtxstatus(struct b43legacy_wldev *dev,
const struct b43legacy_hwtxstatus *hw)
{
struct b43legacy_txstatus status;
u8 tmp;
status.cookie = le16_to_cpu(hw->cookie);
status.seq = le16_to_cpu(hw->seq);
status.phy_stat = hw->phy_stat;
tmp = hw->count;
status.frame_count = (tmp >> 4);
status.rts_count = (tmp & 0x0F);
tmp = hw->flags;
status.supp_reason = ((tmp & 0x1C) >> 2);
status.pm_indicated = !!(tmp & 0x80);
status.intermediate = !!(tmp & 0x40);
status.for_ampdu = !!(tmp & 0x20);
status.acked = !!(tmp & 0x02);
b43legacy_handle_txstatus(dev, &status);
}
/* Stop any TX operation on the device (suspend the hardware queues) */
void b43legacy_tx_suspend(struct b43legacy_wldev *dev)
{
if (b43legacy_using_pio(dev))
b43legacy_pio_freeze_txqueues(dev);
else
b43legacy_dma_tx_suspend(dev);
}
/* Resume any TX operation on the device (resume the hardware queues) */
void b43legacy_tx_resume(struct b43legacy_wldev *dev)
{
if (b43legacy_using_pio(dev))
b43legacy_pio_thaw_txqueues(dev);
else
b43legacy_dma_tx_resume(dev);
}
/* Initialize the QoS parameters */
void b43legacy_qos_init(struct b43legacy_wldev *dev)
{
/* FIXME: This function must probably be called from the mac80211
* config callback. */
return;
b43legacy_hf_write(dev, b43legacy_hf_read(dev) | B43legacy_HF_EDCF);
/* FIXME kill magic */
b43legacy_write16(dev, 0x688,
b43legacy_read16(dev, 0x688) | 0x4);
/*TODO: We might need some stack support here to get the values. */
}