[PATCH rtw-next v7 0/3] wifi: rtw88: channel switch in AP mode

[PATCH rtw-next v7 0/3] wifi: rtw88: channel switch in AP mode

[Mehmet Fide]

From: Mehmet Fide <mehmet.fide@screeningeagle.com>

An rtw88 AP cannot change its channel: the driver does not announce
channel switch support, so hostapd's CHAN_SWITCH is refused and the
only way is to tear the AP down. The series fixes the beacon download
the reserved page build makes twice, implements channel_switch_beacon
on top of the firmware's beacon page, and times the countdown
downloads from the TBTT so that every count goes out on the air.

Tested on an RTL8821CU, an RTL8822CU and an RTL8822BU (USB) with
hostapd 2.10 as AP: switches with counts 1 to 100, scans during a
countdown, hostapd stopped and started, the USB driver unbound and
bound and a firmware crash during a countdown, IBSS switches, a
station interface on the 8822CU associating while its AP counted
down, and Windows and Linux stations following the switches without a
re-association. The 8821CU and 8822CU set was run on a PROVE_LOCKING
kernel without a lockdep report.

Patch 3 was tested on the RTL8821CU with a build that delays every
second countdown download: with a 60 ms delay every count still goes
out (sniffed from a third machine), with 95 ms the delayed count
stays out and the next download follows at once; the AP finishes at
the same time in both cases, and a Windows station followed the
switches with counts 10 and 50 without a re-association. With the
start forced to either side of a TBTT, and with iperf3 traffic, the
counts matched the beacon timing in every run on the RTL8821CU and on
the RTL8822BU, the first on a PREEMPT_RT kernel, the second on a
preemptible one without RT, both with HZ=250. The patch 2 fix was
checked with a build that queues a TIM update right after every
countdown finish: the WARN came before the fix and not after it.
Patch 1 is unchanged since v6.

v7:
- new patch 3: the countdown downloads are timed from the TSF, 10 ms
  after each TBTT, so a download that runs late by less than a beacon
  interval still reaches the firmware before the next beacon; one
  later than that is followed by its successor at once. Ping-Ke's
  question on v6: with the absolute due time a late download and its
  successor could land in one beacon period and leave a count out of
  the air
- patch 3 takes a TBTT within the margin before the start as the one
  that sent the countdown template: a TBTT between the template
  download and the first TSF read made the stations see one count
  twice
- patch 2 keeps csa_vif until the beacon after the switch: a TIM
  update before it fetched one beacon past count 1 and hit the WARN
  in ieee80211_beacon_update_cntdwn()
- rebased on rtw-next

v6:
- the wiphy work patch of v5 is gone: the countdown work is an
  ieee80211 delayed work and csa_vif is driver state, both under the
  driver mutex, so rtw88 takes no wiphy lock anywhere (Ping-Ke)
- rtw_core_stop() cancels the countdown work and clears csa_vif, which
  covers the IPS path and the firmware recovery; the wiphy_lock() in
  the recovery work is gone (Ping-Ke)
- the BSS_CHANGED_BEACON path says why it starts the countdown, the
  replay after a hardware restart, and stops it when the beacon comes
  back without a switch announced (Ping-Ke)
- the downloads are paced from the first one with an absolute due
  time. Queued after each download, they drifted by about 10 ms per
  beacon interval on the ordered mac80211 workqueue; on a count of 50
  the AP switched half a second after its station had, and the
  station re-associated

v5:
- 2/3 is new: update_beacon_work becomes a wiphy work, so that it can
  look at the channel switch state under the wiphy lock; it checks
  RTW_FLAG_RUNNING instead of being cancelled in rtw_core_stop(), which
  runs without the wiphy lock on the IPS path (Ping-Ke); reverted in v6
- 3/3: rtw_fw_csa_active/start/stop() assert the wiphy lock (Ping-Ke);
  reverted in v6, they assert the driver mutex
- 3/3: hw_scan() takes the mutex with guard() (Ping-Ke)
- 3/3: a comment on the association download names the STA+AP
  combination it skips the download for (Ping-Ke)
- the whole set ran on a PROVE_LOCKING kernel without a lockdep report:
  switches with counts 1 to 100, hostapd stopped and restarted during
  a countdown, scans during a countdown, a firmware crash during a
  countdown, three stop/idle/start cycles, IBSS, 50 switches with a
  station attached, and on the RTL8822CU a station interface
  associating while the AP interface counted down

v4:
- 1/2: Reviewed-by from Luka
- 2/2: the countdown work is back in the device, initialised once,
  with csa_vif naming the interface; no interface iteration and no
  lookup through the reserved page any more (Ping-Ke)
- 2/2: the countdown is cancelled before a firmware recovery restarts
  the hardware, instead of guarding the work with flags (Ping-Ke)
- 2/2: the page download on association skips a running countdown,
  like the TIM update and the PG backup (Luka)
- 2/2: the scan refusal comes before the scan offload test, so that
  firmware without scan offload does not fall back to a software scan
  during a countdown (Luka)

v3:
- 1/2: the beacon out-pointer is initialised in the caller (Luka)
- 2/2: the countdown work lives in the interface, remove_interface
  cancels it unconditionally, the queue wrapper and the comments are
  gone (Ping-Ke)
- 2/2: the TIM update and the PG backup on set_key skip the page
  download while a switch is announced; every beacon fetch advances
  the countdown (Luka)
- 2/2: the commit message names the refused hardware scan (Ping-Ke)

v2:
- 2/2: a hardware scan is refused while a switch is announced
- the rtw89 mention is gone from the cover

Mehmet Fide (3):
  wifi: rtw88: download the beacon the reserved page was built with
  wifi: rtw88: support channel switch in AP mode
  wifi: rtw88: time the countdown downloads from the TBTT

 drivers/net/wireless/realtek/rtw88/fw.c       | 146 ++++++++++++++++--
 drivers/net/wireless/realtek/rtw88/fw.h       |   4 +
 drivers/net/wireless/realtek/rtw88/mac80211.c |  39 ++++-
 drivers/net/wireless/realtek/rtw88/main.c     |   6 +-
 drivers/net/wireless/realtek/rtw88/main.h     |   3 +
 drivers/net/wireless/realtek/rtw88/reg.h      |   1 +
 6 files changed, 178 insertions(+), 21 deletions(-)


base-commit: 9b0be45d4d52fd223994e151f169743a97abd290
-- 
2.55.0

[PATCH rtw-next v7 1/3] wifi: rtw88: download the beacon the reserved page was built with

[Mehmet Fide]

From: Mehmet Fide <mehmet.fide@screeningeagle.com>

rtw_fw_download_rsvd_page() downloads the beacon twice: once as part of
the reserved page and once more on its own, so that the firmware ends up
with a TX descriptor that describes the beacon rather than the whole
page. The second download fetched a new beacon from mac80211 instead of
downloading the one the page already holds.

Besides the extra work, every beacon fetch advances the DTIM count and,
while a channel switch is announced, the CSA countdown; doing it twice
per update lets a countdown that starts at 2 reach 0, which mac80211
warns about. Hand the beacon skb out of the page build and download
that. The hw scan, which downloads the beacon without a page build,
keeps fetching its own.

Signed-off-by: Mehmet Fide <mehmet.fide@screeningeagle.com>
Reviewed-by: Luka Gejak <luka.gejak@linux.dev>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
---

Notes:
    Changes in v7:
    - none, rebased on rtw-next
    
    Changes in v6:
    - none
    
    Changes in v5:
    - none
    
    Changes in v4:
    - none, rebased on rtw-next
    
    Changes in v3:
    - the beacon out-pointer is initialised in the caller

 drivers/net/wireless/realtek/rtw88/fw.c | 34 +++++++++++++++----------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw88/fw.c b/drivers/net/wireless/realtek/rtw88/fw.c
index 945fedcd375b..3cd17a3bb494 100644
--- a/drivers/net/wireless/realtek/rtw88/fw.c
+++ b/drivers/net/wireless/realtek/rtw88/fw.c
@@ -1622,7 +1622,8 @@ static int  __rtw_build_rsvd_page_from_vifs(struct rtw_dev *rtwdev)
 	return 0;
 }
 
-static u8 *rtw_build_rsvd_page(struct rtw_dev *rtwdev, u32 *size)
+static u8 *rtw_build_rsvd_page(struct rtw_dev *rtwdev, u32 *size,
+			       struct sk_buff **beacon)
 {
 	const struct rtw_chip_info *chip = rtwdev->chip;
 	struct ieee80211_hw *hw = rtwdev->hw;
@@ -1702,13 +1703,15 @@ static u8 *rtw_build_rsvd_page(struct rtw_dev *rtwdev, u32 *size)
 	list_for_each_entry(rsvd_pkt, &rtwdev->rsvd_page_list, build_list) {
 		rtw_rsvd_page_list_to_buf(rtwdev, page_size, page_margin,
 					  page, buf, rsvd_pkt);
-		if (page == 0)
+		if (page == 0) {
 			page += rtw_len_to_page(rsvd_pkt->skb->len +
 						tx_desc_sz, page_size);
-		else
+			/* the caller downloads it once more on its own */
+			*beacon = rsvd_pkt->skb;
+		} else {
 			page += rtw_len_to_page(rsvd_pkt->skb->len, page_size);
-
-		kfree_skb(rsvd_pkt->skb);
+			kfree_skb(rsvd_pkt->skb);
+		}
 		rsvd_pkt->skb = NULL;
 	}
 
@@ -1723,11 +1726,12 @@ static u8 *rtw_build_rsvd_page(struct rtw_dev *rtwdev, u32 *size)
 	return NULL;
 }
 
-static int rtw_download_beacon(struct rtw_dev *rtwdev)
+/* the beacon the page was built with, or a fresh one for the hw scan */
+static int rtw_download_beacon(struct rtw_dev *rtwdev, struct sk_buff *beacon)
 {
 	struct ieee80211_hw *hw = rtwdev->hw;
 	struct rtw_rsvd_page *rsvd_pkt;
-	struct sk_buff *skb;
+	struct sk_buff *skb = beacon;
 	int ret = 0;
 
 	rsvd_pkt = list_first_entry_or_null(&rtwdev->rsvd_page_list,
@@ -1744,7 +1748,8 @@ static int rtw_download_beacon(struct rtw_dev *rtwdev)
 		return -EINVAL;
 	}
 
-	skb = rtw_get_rsvd_page_skb(hw, rsvd_pkt);
+	if (!skb)
+		skb = rtw_get_rsvd_page_skb(hw, rsvd_pkt);
 	if (!skb) {
 		rtw_err(rtwdev, "failed to get beacon skb\n");
 		return -ENOMEM;
@@ -1754,18 +1759,20 @@ static int rtw_download_beacon(struct rtw_dev *rtwdev)
 	if (ret)
 		rtw_err(rtwdev, "failed to download drv rsvd page\n");
 
-	dev_kfree_skb(skb);
+	if (!beacon)
+		dev_kfree_skb(skb);
 
 	return ret;
 }
 
 int rtw_fw_download_rsvd_page(struct rtw_dev *rtwdev)
 {
-	u8 *buf;
+	struct sk_buff *beacon = NULL;
 	u32 size;
+	u8 *buf;
 	int ret;
 
-	buf = rtw_build_rsvd_page(rtwdev, &size);
+	buf = rtw_build_rsvd_page(rtwdev, &size, &beacon);
 	if (!buf) {
 		rtw_err(rtwdev, "failed to build rsvd page pkt\n");
 		return -ENOMEM;
@@ -1782,13 +1789,14 @@ int rtw_fw_download_rsvd_page(struct rtw_dev *rtwdev)
 	 * the beacon again to replace the TX desc header, and we will get
 	 * a correct tx_desc for the beacon in the rsvd page.
 	 */
-	ret = rtw_download_beacon(rtwdev);
+	ret = rtw_download_beacon(rtwdev, beacon);
 	if (ret) {
 		rtw_err(rtwdev, "failed to download beacon\n");
 		goto free;
 	}
 
 free:
+	dev_kfree_skb(beacon);
 	kfree(buf);
 
 	return ret;
@@ -2345,7 +2353,7 @@ int rtw_hw_scan_offload(struct rtw_dev *rtwdev, struct ieee80211_vif *vif,
 	rtw_fw_set_scan_offload(rtwdev, &cs_option, rtwvif, &chan_list);
 out:
 	if (rtwdev->ap_active) {
-		ret = rtw_download_beacon(rtwdev);
+		ret = rtw_download_beacon(rtwdev, NULL);
 		if (ret)
 			rtw_err(rtwdev, "HW scan download beacon failed\n");
 	}
-- 
2.55.0

[PATCH rtw-next v7 2/3] wifi: rtw88: support channel switch in AP mode

[Mehmet Fide]

From: Mehmet Fide <mehmet.fide@screeningeagle.com>

hostapd's CHAN_SWITCH is refused because the driver does not announce
channel switch support, so an rtw88 AP can only change its channel by
being torn down and started again.

Declare WIPHY_FLAG_HAS_CHANNEL_SWITCH and implement
channel_switch_beacon: the firmware repeats the beacon held in the
first reserved page, so while a switch is announced the page is
downloaded again every beacon interval to advance the countdown, and
ieee80211_csa_finish() is called once it completes. IBSS shares the
page and the work.

The work is a delayed work of the device and csa_vif names the
interface, both under the driver mutex. The countdown is cancelled when
the AP stops, when the interface goes away, on WoWLAN suspend and in
rtw_core_stop(); the BSS_CHANGED_BEACON replay after a hardware restart
resumes it. The other page downloads during a countdown, the TIM update,
the PG backup and the one on association, are skipped until the beacon
after the switch, since every beacon fetch advances the countdown; the
next download carries their changes. A scan is refused: it would take
the AP off the channel its stations count down to.

Signed-off-by: Mehmet Fide <mehmet.fide@screeningeagle.com>
---

Notes:
    Changes in v7:
    - csa_vif is kept until the beacon after the switch: a TIM update
      before it fetched one beacon past count 1 and hit the WARN in
      ieee80211_beacon_update_cntdwn()
    - rebased on rtw-next
    
    Changes in v6:
    - the countdown work is an ieee80211 delayed work under the driver
      mutex, csa_vif is driver state under the mutex; no wiphy lock in
      rtw88 (Ping-Ke)
    - rtw_core_stop() cancels the work and clears csa_vif, which covers the
      IPS path and the firmware recovery (Ping-Ke)
    - the downloads are paced from the first one with an absolute due time:
      queued after each download, the countdown drifted by about 10 ms per
      beacon interval on the ordered mac80211 workqueue, and a station
      switched ahead of the AP on a count of 50
    - the BSS_CHANGED_BEACON path says why it starts the countdown (the
      replay after a hardware restart) and stops it when the beacon comes
      back without a switch announced (Ping-Ke)
    
    Changes in v5:
    - rtw_fw_csa_active/start/stop() assert the wiphy lock
    - hw_scan() takes the mutex with guard()
    - the ASSOC path says why it skips the download: the STA+AP combination
    
    Changes in v4:
    - the work and csa_vif live in rtw_dev; no lookup through the reserved page
    - the countdown is stopped before a firmware recovery restarts the hardware
    - a scan is refused while a switch is announced
    - one beacon fetch per interval during the countdown

 drivers/net/wireless/realtek/rtw88/fw.c       | 80 ++++++++++++++++++-
 drivers/net/wireless/realtek/rtw88/fw.h       |  4 +
 drivers/net/wireless/realtek/rtw88/mac80211.c | 39 +++++++--
 drivers/net/wireless/realtek/rtw88/main.c     |  6 +-
 drivers/net/wireless/realtek/rtw88/main.h     |  3 +
 5 files changed, 124 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw88/fw.c b/drivers/net/wireless/realtek/rtw88/fw.c
index 3cd17a3bb494..2d81aaeed0d7 100644
--- a/drivers/net/wireless/realtek/rtw88/fw.c
+++ b/drivers/net/wireless/realtek/rtw88/fw.c
@@ -1802,14 +1802,90 @@ int rtw_fw_download_rsvd_page(struct rtw_dev *rtwdev)
 	return ret;
 }
 
+bool rtw_fw_csa_active(struct rtw_dev *rtwdev)
+{
+	lockdep_assert_held(&rtwdev->mutex);
+
+	return !!rtwdev->csa_vif;
+}
+
+/* paced from the first download: a late one does not delay the next */
+static void rtw_fw_csa_queue(struct rtw_dev *rtwdev, struct ieee80211_vif *vif)
+{
+	u32 interval = ieee80211_tu_to_usec(vif->bss_conf.beacon_int);
+	s64 delay;
+
+	rtwdev->csa_due = ktime_add_us(rtwdev->csa_due, interval);
+	delay = ktime_us_delta(rtwdev->csa_due, ktime_get());
+	ieee80211_queue_delayed_work(rtwdev->hw, &rtwdev->csa_beacon_work,
+				     usecs_to_jiffies(max(delay, 0)));
+}
+
+void rtw_fw_csa_start(struct rtw_dev *rtwdev, struct ieee80211_vif *vif)
+{
+	lockdep_assert_held(&rtwdev->mutex);
+
+	if (rtwdev->csa_vif == vif)
+		return;
+
+	rtwdev->csa_vif = vif;
+	rtwdev->csa_due = ktime_get();
+	rtw_fw_csa_queue(rtwdev, vif);
+}
+
+void rtw_fw_csa_stop(struct rtw_dev *rtwdev, struct ieee80211_vif *vif)
+{
+	lockdep_assert_held(&rtwdev->mutex);
+
+	if (!vif || rtwdev->csa_vif != vif)
+		return;
+
+	rtwdev->csa_vif = NULL;
+	cancel_delayed_work(&rtwdev->csa_beacon_work);
+}
+
 void rtw_fw_update_beacon_work(struct work_struct *work)
 {
 	struct rtw_dev *rtwdev = container_of(work, struct rtw_dev,
 					      update_beacon_work);
 
 	mutex_lock(&rtwdev->mutex);
-	rtw_fw_download_rsvd_page(rtwdev);
-	rtw_send_rsvd_page_h2c(rtwdev);
+
+	/* a fetch advances the countdown, the next download carries the TIM */
+	if (!rtw_fw_csa_active(rtwdev)) {
+		rtw_fw_download_rsvd_page(rtwdev);
+		rtw_send_rsvd_page_h2c(rtwdev);
+	}
+
+	mutex_unlock(&rtwdev->mutex);
+}
+
+void rtw_fw_csa_beacon_work(struct work_struct *work)
+{
+	struct rtw_dev *rtwdev = container_of(work, struct rtw_dev,
+					      csa_beacon_work.work);
+	struct ieee80211_vif *vif;
+
+	mutex_lock(&rtwdev->mutex);
+
+	vif = rtwdev->csa_vif;
+	if (!vif)
+		goto out;
+
+	if (!vif->bss_conf.csa_active) {
+		rtwdev->csa_vif = NULL;
+		goto out;
+	}
+
+	if (!ieee80211_beacon_cntdwn_is_complete(vif, 0)) {
+		rtw_fw_download_rsvd_page(rtwdev);
+		rtw_send_rsvd_page_h2c(rtwdev);
+		rtw_fw_csa_queue(rtwdev, vif);
+	} else {
+		ieee80211_csa_finish(vif, 0);
+	}
+
+out:
 	mutex_unlock(&rtwdev->mutex);
 }
 
diff --git a/drivers/net/wireless/realtek/rtw88/fw.h b/drivers/net/wireless/realtek/rtw88/fw.h
index 48ad9ceab6ea..d8e58e4ed836 100644
--- a/drivers/net/wireless/realtek/rtw88/fw.h
+++ b/drivers/net/wireless/realtek/rtw88/fw.h
@@ -863,7 +863,11 @@ void rtw_add_rsvd_page_pno(struct rtw_dev *rtwdev,
 void rtw_add_rsvd_page_sta(struct rtw_dev *rtwdev,
 			   struct rtw_vif *rtwvif);
 int rtw_fw_download_rsvd_page(struct rtw_dev *rtwdev);
+bool rtw_fw_csa_active(struct rtw_dev *rtwdev);
+void rtw_fw_csa_start(struct rtw_dev *rtwdev, struct ieee80211_vif *vif);
+void rtw_fw_csa_stop(struct rtw_dev *rtwdev, struct ieee80211_vif *vif);
 void rtw_fw_update_beacon_work(struct work_struct *work);
+void rtw_fw_csa_beacon_work(struct work_struct *work);
 void rtw_send_rsvd_page_h2c(struct rtw_dev *rtwdev);
 int rtw_dump_drv_rsvd_page(struct rtw_dev *rtwdev,
 			   u32 offset, u32 size, u32 *buf);
diff --git a/drivers/net/wireless/realtek/rtw88/mac80211.c b/drivers/net/wireless/realtek/rtw88/mac80211.c
index 2a9b09fa76e7..182aecc76820 100644
--- a/drivers/net/wireless/realtek/rtw88/mac80211.c
+++ b/drivers/net/wireless/realtek/rtw88/mac80211.c
@@ -237,6 +237,8 @@ static void rtw_ops_remove_interface(struct ieee80211_hw *hw,
 
 	mutex_lock(&rtwdev->mutex);
 
+	rtw_fw_csa_stop(rtwdev, vif);
+
 	rtw_leave_lps_deep(rtwdev);
 
 	rtw_txq_cleanup(rtwdev, vif->txq);
@@ -395,8 +397,11 @@ static void rtw_ops_bss_info_changed(struct ieee80211_hw *hw,
 		if (vif->cfg.assoc) {
 			rtw_coex_connect_notify(rtwdev, COEX_ASSOCIATE_FINISH);
 
-			rtw_fw_download_rsvd_page(rtwdev);
-			rtw_send_rsvd_page_h2c(rtwdev);
+			/* a station associating while the AP counts down */
+			if (!rtw_fw_csa_active(rtwdev)) {
+				rtw_fw_download_rsvd_page(rtwdev);
+				rtw_send_rsvd_page_h2c(rtwdev);
+			}
 			rtw_fw_default_port(rtwdev, rtwvif);
 			rtw_coex_media_status_notify(rtwdev, vif->cfg.assoc);
 			if (rtw_bf_support)
@@ -438,6 +443,11 @@ static void rtw_ops_bss_info_changed(struct ieee80211_hw *hw,
 		rtw_set_dtim_period(rtwdev, conf->dtim_period);
 		rtw_fw_download_rsvd_page(rtwdev);
 		rtw_send_rsvd_page_h2c(rtwdev);
+		/* restart replay resumes it, a beacon without CSA ends it */
+		if (conf->csa_active)
+			rtw_fw_csa_start(rtwdev, vif);
+		else
+			rtw_fw_csa_stop(rtwdev, vif);
 	}
 
 	if (changed & BSS_CHANGED_BEACON_ENABLED) {
@@ -490,6 +500,7 @@ static void rtw_ops_stop_ap(struct ieee80211_hw *hw,
 	struct rtw_dev *rtwdev = hw->priv;
 
 	mutex_lock(&rtwdev->mutex);
+	rtw_fw_csa_stop(rtwdev, vif);
 	rtw_write32_clr(rtwdev, REG_TCR, BIT_TCR_UPDATE_HGQMD);
 	rtw_write16(rtwdev, REG_ATIMWND, ATIMWND_DEFAULT);
 	rtwdev->ap_active = false;
@@ -556,6 +567,17 @@ static int rtw_ops_set_tim(struct ieee80211_hw *hw, struct ieee80211_sta *sta,
 	return 0;
 }
 
+static void rtw_ops_channel_switch_beacon(struct ieee80211_hw *hw,
+					  struct ieee80211_vif *vif,
+					  struct cfg80211_chan_def *chandef)
+{
+	struct rtw_dev *rtwdev = hw->priv;
+
+	mutex_lock(&rtwdev->mutex);
+	rtw_fw_csa_start(rtwdev, vif);
+	mutex_unlock(&rtwdev->mutex);
+}
+
 static int rtw_ops_set_key(struct ieee80211_hw *hw, enum set_key_cmd cmd,
 			   struct ieee80211_vif *vif, struct ieee80211_sta *sta,
 			   struct ieee80211_key_conf *key)
@@ -626,7 +648,8 @@ static int rtw_ops_set_key(struct ieee80211_hw *hw, enum set_key_cmd cmd,
 	}
 
 	/* download new cam settings for PG to backup */
-	if (rtw_get_lps_deep_mode(rtwdev) == LPS_DEEP_MODE_PG)
+	if (rtw_get_lps_deep_mode(rtwdev) == LPS_DEEP_MODE_PG &&
+	    !rtw_fw_csa_active(rtwdev))
 		rtw_fw_download_rsvd_page(rtwdev);
 
 out:
@@ -846,6 +869,7 @@ static int rtw_ops_suspend(struct ieee80211_hw *hw,
 	int ret;
 
 	mutex_lock(&rtwdev->mutex);
+	rtw_fw_csa_stop(rtwdev, rtwdev->csa_vif);
 	ret = rtw_wow_suspend(rtwdev, wowlan);
 	if (ret)
 		rtw_err(rtwdev, "failed to suspend for wow %d\n", ret);
@@ -893,20 +917,24 @@ static int rtw_ops_hw_scan(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 	struct rtw_dev *rtwdev = hw->priv;
 	int ret;
 
+	guard(mutex)(&rtwdev->mutex);
+
+	/* a scan takes the AP off the channel its stations count down to */
+	if (rtw_fw_csa_active(rtwdev))
+		return -EBUSY;
+
 	if (!rtw_fw_feature_check(&rtwdev->fw, FW_FEATURE_SCAN_OFFLOAD))
 		return 1;
 
 	if (test_bit(RTW_FLAG_SCANNING, rtwdev->flags))
 		return -EBUSY;
 
-	mutex_lock(&rtwdev->mutex);
 	rtw_hw_scan_start(rtwdev, vif, req);
 	ret = rtw_hw_scan_offload(rtwdev, vif, true);
 	if (ret) {
 		rtw_hw_scan_abort(rtwdev);
 		rtw_err(rtwdev, "HW scan failed with status: %d\n", ret);
 	}
-	mutex_unlock(&rtwdev->mutex);
 
 	return ret;
 }
@@ -973,6 +1001,7 @@ const struct ieee80211_ops rtw_ops = {
 	.sta_add		= rtw_ops_sta_add,
 	.sta_remove		= rtw_ops_sta_remove,
 	.set_tim		= rtw_ops_set_tim,
+	.channel_switch_beacon	= rtw_ops_channel_switch_beacon,
 	.set_key		= rtw_ops_set_key,
 	.ampdu_action		= rtw_ops_ampdu_action,
 	.can_aggregate_in_amsdu	= rtw_ops_can_aggregate_in_amsdu,
diff --git a/drivers/net/wireless/realtek/rtw88/main.c b/drivers/net/wireless/realtek/rtw88/main.c
index 0f23498b5c96..48e8cad221b9 100644
--- a/drivers/net/wireless/realtek/rtw88/main.c
+++ b/drivers/net/wireless/realtek/rtw88/main.c
@@ -1550,11 +1550,13 @@ void rtw_core_stop(struct rtw_dev *rtwdev)
 
 	clear_bit(RTW_FLAG_RUNNING, rtwdev->flags);
 	clear_bit(RTW_FLAG_FW_RUNNING, rtwdev->flags);
+	rtwdev->csa_vif = NULL;
 
 	mutex_unlock(&rtwdev->mutex);
 
 	cancel_work_sync(&rtwdev->c2h_work);
 	cancel_work_sync(&rtwdev->update_beacon_work);
+	cancel_delayed_work_sync(&rtwdev->csa_beacon_work);
 	cancel_delayed_work_sync(&rtwdev->watch_dog_work);
 	cancel_delayed_work_sync(&coex->bt_relink_work);
 	cancel_delayed_work_sync(&coex->bt_reenable_work);
@@ -2170,6 +2172,7 @@ int rtw_core_init(struct rtw_dev *rtwdev)
 	INIT_WORK(&rtwdev->ips_work, rtw_ips_work);
 	INIT_WORK(&rtwdev->fw_recovery_work, rtw_fw_recovery_work);
 	INIT_WORK(&rtwdev->update_beacon_work, rtw_fw_update_beacon_work);
+	INIT_DELAYED_WORK(&rtwdev->csa_beacon_work, rtw_fw_csa_beacon_work);
 	INIT_WORK(&rtwdev->ba_work, rtw_txq_ba_work);
 	skb_queue_head_init(&rtwdev->c2h_queue);
 	skb_queue_head_init(&rtwdev->coex.queue);
@@ -2293,7 +2296,8 @@ int rtw_register_hw(struct rtw_dev *rtwdev, struct ieee80211_hw *hw)
 	hw->wiphy->available_antennas_rx = hal->antenna_rx;
 
 	hw->wiphy->flags |= WIPHY_FLAG_SUPPORTS_TDLS |
-			    WIPHY_FLAG_TDLS_EXTERNAL_SETUP;
+			    WIPHY_FLAG_TDLS_EXTERNAL_SETUP |
+			    WIPHY_FLAG_HAS_CHANNEL_SWITCH;
 
 	hw->wiphy->features |= NL80211_FEATURE_SCAN_RANDOM_MAC_ADDR;
 	hw->wiphy->max_scan_ssids = RTW_SCAN_MAX_SSIDS;
diff --git a/drivers/net/wireless/realtek/rtw88/main.h b/drivers/net/wireless/realtek/rtw88/main.h
index d59f6e323adf..bc3ebfec11ae 100644
--- a/drivers/net/wireless/realtek/rtw88/main.h
+++ b/drivers/net/wireless/realtek/rtw88/main.h
@@ -2094,6 +2094,9 @@ struct rtw_dev {
 	struct work_struct ips_work;
 	struct work_struct fw_recovery_work;
 	struct work_struct update_beacon_work;
+	struct delayed_work csa_beacon_work;
+	struct ieee80211_vif *csa_vif;
+	ktime_t csa_due;
 
 	/* used to protect txqs list */
 	spinlock_t txq_lock;
-- 
2.55.0

[PATCH rtw-next v7 3/3] wifi: rtw88: time the countdown downloads from the TBTT

[Mehmet Fide]

From: Mehmet Fide <mehmet.fide@screeningeagle.com>

The countdown downloads are queued one beacon interval apart, with no
relation to the TBTT. A download that runs late past the next TBTT
leaves a count out of the air.

Queue each download 10 ms after the next TBTT, read from the TSF, so it
may run late by almost a beacon interval; a later one is followed by
the next at once. A TSF jump, an IBSS merge or a reset, restarts the
schedule from the next TBTT.

A TBTT just before the start may already have sent the first count; it
is taken as the one that did, so no count is sent twice.

The USB chips raise no TBTT interrupt, so the TSF register is read. The
beaconing interface is always on port 0: rtw_core_port_switch() moves
an AP there, an IBSS runs alone.

Signed-off-by: Mehmet Fide <mehmet.fide@screeningeagle.com>
---

Notes:
    Changes in v7:
    - new patch, from Ping-Ke's review of the countdown pacing in v6

 drivers/net/wireless/realtek/rtw88/fw.c   | 40 ++++++++++++++++++++---
 drivers/net/wireless/realtek/rtw88/main.h |  2 +-
 drivers/net/wireless/realtek/rtw88/reg.h  |  1 +
 3 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw88/fw.c b/drivers/net/wireless/realtek/rtw88/fw.c
index 2d81aaeed0d7..c5a106a59540 100644
--- a/drivers/net/wireless/realtek/rtw88/fw.c
+++ b/drivers/net/wireless/realtek/rtw88/fw.c
@@ -3,6 +3,7 @@
  */
 
 #include <linux/iopoll.h>
+#include <linux/math64.h>
 
 #include "main.h"
 #include "coex.h"
@@ -1809,27 +1810,58 @@ bool rtw_fw_csa_active(struct rtw_dev *rtwdev)
 	return !!rtwdev->csa_vif;
 }
 
-/* paced from the first download: a late one does not delay the next */
+#define RTW_CSA_TBTT_MARGIN_US	10000
+
+/* the beaconing interface is always on port 0 */
+static u64 rtw_fw_read_tsf(struct rtw_dev *rtwdev)
+{
+	u32 hi, lo;
+
+	do {
+		hi = rtw_read32(rtwdev, REG_TSFTR + 4);
+		lo = rtw_read32(rtwdev, REG_TSFTR);
+	} while (hi != rtw_read32(rtwdev, REG_TSFTR + 4));
+
+	return ((u64)hi << 32) | lo;
+}
+
 static void rtw_fw_csa_queue(struct rtw_dev *rtwdev, struct ieee80211_vif *vif)
 {
 	u32 interval = ieee80211_tu_to_usec(vif->bss_conf.beacon_int);
+	u64 tsf = rtw_fw_read_tsf(rtwdev);
 	s64 delay;
+	u32 rem;
 
-	rtwdev->csa_due = ktime_add_us(rtwdev->csa_due, interval);
-	delay = ktime_us_delta(rtwdev->csa_due, ktime_get());
+	rtwdev->csa_tbtt += interval;
+	delay = rtwdev->csa_tbtt + RTW_CSA_TBTT_MARGIN_US - tsf;
+	if (delay > interval + RTW_CSA_TBTT_MARGIN_US ||
+	    delay < -(s64)interval) {
+		/* the TSF jumped: restart from the next TBTT */
+		div_u64_rem(tsf, interval, &rem);
+		rtwdev->csa_tbtt = tsf - rem + interval;
+		delay = rtwdev->csa_tbtt + RTW_CSA_TBTT_MARGIN_US - tsf;
+	}
 	ieee80211_queue_delayed_work(rtwdev->hw, &rtwdev->csa_beacon_work,
 				     usecs_to_jiffies(max(delay, 0)));
 }
 
 void rtw_fw_csa_start(struct rtw_dev *rtwdev, struct ieee80211_vif *vif)
 {
+	u32 interval = ieee80211_tu_to_usec(vif->bss_conf.beacon_int);
+	u32 rem;
+
 	lockdep_assert_held(&rtwdev->mutex);
 
 	if (rtwdev->csa_vif == vif)
 		return;
 
 	rtwdev->csa_vif = vif;
-	rtwdev->csa_due = ktime_get();
+	rtwdev->csa_tbtt = rtw_fw_read_tsf(rtwdev);
+	div_u64_rem(rtwdev->csa_tbtt, interval, &rem);
+	rtwdev->csa_tbtt -= rem;
+	/* a TBTT that just passed may have sent the first count already */
+	if (rem < RTW_CSA_TBTT_MARGIN_US)
+		rtwdev->csa_tbtt -= interval;
 	rtw_fw_csa_queue(rtwdev, vif);
 }
 
diff --git a/drivers/net/wireless/realtek/rtw88/main.h b/drivers/net/wireless/realtek/rtw88/main.h
index bc3ebfec11ae..3be0a96d1186 100644
--- a/drivers/net/wireless/realtek/rtw88/main.h
+++ b/drivers/net/wireless/realtek/rtw88/main.h
@@ -2096,7 +2096,7 @@ struct rtw_dev {
 	struct work_struct update_beacon_work;
 	struct delayed_work csa_beacon_work;
 	struct ieee80211_vif *csa_vif;
-	ktime_t csa_due;
+	u64 csa_tbtt;
 
 	/* used to protect txqs list */
 	spinlock_t txq_lock;
diff --git a/drivers/net/wireless/realtek/rtw88/reg.h b/drivers/net/wireless/realtek/rtw88/reg.h
index afcdb66fdb9a..3ff4ae0885ef 100644
--- a/drivers/net/wireless/realtek/rtw88/reg.h
+++ b/drivers/net/wireless/realtek/rtw88/reg.h
@@ -506,6 +506,7 @@
 #define REG_USTIME_TSF		0x055C
 #define REG_BCN_MAX_ERR		0x055D
 #define REG_RXTSF_OFFSET_CCK	0x055E
+#define REG_TSFTR		0x0560
 #define REG_MISC_CTRL		0x0577
 #define BIT_EN_FREE_CNT		BIT(3)
 #define BIT_DIS_SECOND_CCA	(BIT(0) | BIT(1))
-- 
2.55.0