wifi: wfx: introduce hif_scan_uniq()

Like hof_scan(), hif_scan_uniq() invoke HIF_SCAN. However, it only
allows to probe one channel and disable probe requests. It works very
well to implement Remain-On-Channel.
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20231004172843.195332-5-jerome.pouiller@silabs.com

drivers/net/wireless/silabs/wfx/hif_tx.c

@@ -238,6 +238,31 @@ int wfx_hif_write_mib(struct wfx_dev *wdev, int vif_id, u16 mib_id, void *val, s
 	return ret;
 }
 
+/* Hijack scan request to implement Remain-On-Channel */
+int wfx_hif_scan_uniq(struct wfx_vif *wvif, struct ieee80211_channel *chan, int duration)
+{
+	int ret;
+	struct wfx_hif_msg *hif;
+	size_t buf_len = sizeof(struct wfx_hif_req_start_scan_alt) + sizeof(u8);
+	struct wfx_hif_req_start_scan_alt *body = wfx_alloc_hif(buf_len, &hif);
+
+	if (!hif)
+		return -ENOMEM;
+	body->num_of_ssids = HIF_API_MAX_NB_SSIDS;
+	body->maintain_current_bss = 1;
+	body->disallow_ps = 1;
+	body->tx_power_level = cpu_to_le32(chan->max_power);
+	body->num_of_channels = 1;
+	body->channel_list[0] = chan->hw_value;
+	body->max_transmit_rate = API_RATE_INDEX_B_1MBPS;
+	body->min_channel_time = cpu_to_le32(duration);
+	body->max_channel_time = cpu_to_le32(duration * 110 / 100);
+	wfx_fill_header(hif, wvif->id, HIF_REQ_ID_START_SCAN, buf_len);
+	ret = wfx_cmd_send(wvif->wdev, hif, NULL, 0, false);
+	kfree(hif);
+	return ret;
+}
+
 int wfx_hif_scan(struct wfx_vif *wvif, struct cfg80211_scan_request *req,
 		 int chan_start_idx, int chan_num)
 {

drivers/net/wireless/silabs/wfx/hif_tx.h

@@ -54,6 +54,7 @@ int wfx_hif_beacon_transmit(struct wfx_vif *wvif, bool enable);
 int wfx_hif_update_ie_beacon(struct wfx_vif *wvif, const u8 *ies, size_t ies_len);
 int wfx_hif_scan(struct wfx_vif *wvif, struct cfg80211_scan_request *req80211,
 		 int chan_start, int chan_num);
+int wfx_hif_scan_uniq(struct wfx_vif *wvif, struct ieee80211_channel *chan, int duration);
 int wfx_hif_stop_scan(struct wfx_vif *wvif);
 int wfx_hif_configuration(struct wfx_dev *wdev, const u8 *conf, size_t len);
 int wfx_hif_shutdown(struct wfx_dev *wdev);