wcn36xx: Implement Idle Mode Power Save

Idle Mode Power Save (IMPS) is a power saving mechanism which when called
by wcn36xx will cause the radio hardware to enter power collapse.

This particular call maps nicely to a simple conjunction/disjunction around
IEEE80211_CONF_CHANGE_IDLE and IEEE80211_CONF_IDLE.

Here we enter idle when we are not associated with an AP. The kernel will
incrementally toggle idle on/off in the process of trying to establish a
connection, thus saving power until we are connected to the AP again, at
which point we give way to BMPS if power_save is on.

We've validated that with IMPS an apq8039 device which has the wcn36xx
module loaded but, has not authenticated with an AP will get to VMIN on
suspend and will not without IMPS.
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Tested-by: Benjamin Li <benl@squareup.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210909153320.2624649-1-bryan.odonoghue@linaro.org

drivers/net/wireless/ath/wcn36xx/hal.h

@@ -3384,11 +3384,11 @@ struct tl_hal_flush_ac_rsp_msg {
 
 struct wcn36xx_hal_enter_imps_req_msg {
 	struct wcn36xx_hal_msg_header header;
-};
+} __packed;
 
-struct wcn36xx_hal_exit_imps_req {
+struct wcn36xx_hal_exit_imps_req_msg {
 	struct wcn36xx_hal_msg_header header;
-};
+} __packed;
 
 struct wcn36xx_hal_enter_bmps_req_msg {
 	struct wcn36xx_hal_msg_header header;

drivers/net/wireless/ath/wcn36xx/main.c

@@ -432,6 +432,13 @@ static int wcn36xx_config(struct ieee80211_hw *hw, u32 changed)
 	if (changed & IEEE80211_CONF_CHANGE_PS)
 		wcn36xx_change_ps(wcn, hw->conf.flags & IEEE80211_CONF_PS);
 
+	if (changed & IEEE80211_CONF_CHANGE_IDLE) {
+		if (hw->conf.flags & IEEE80211_CONF_IDLE)
+			wcn36xx_smd_enter_imps(wcn);
+		else
+			wcn36xx_smd_exit_imps(wcn);
+	}
+
 	mutex_unlock(&wcn->conf_mutex);
 
 	return 0;

drivers/net/wireless/ath/wcn36xx/smd.c

@@ -2184,6 +2184,59 @@ int wcn36xx_smd_exit_bmps(struct wcn36xx *wcn, struct ieee80211_vif *vif)
 	return ret;
 }
 
+int wcn36xx_smd_enter_imps(struct wcn36xx *wcn)
+{
+	struct wcn36xx_hal_enter_imps_req_msg msg_body;
+	int ret;
+
+	mutex_lock(&wcn->hal_mutex);
+	INIT_HAL_MSG(msg_body, WCN36XX_HAL_ENTER_IMPS_REQ);
+
+	PREPARE_HAL_BUF(wcn->hal_buf, msg_body);
+
+	ret = wcn36xx_smd_send_and_wait(wcn, msg_body.header.len);
+	if (ret) {
+		wcn36xx_err("Sending hal_enter_imps failed\n");
+		goto out;
+	}
+	ret = wcn36xx_smd_rsp_status_check(wcn->hal_buf, wcn->hal_rsp_len);
+	if (ret) {
+		wcn36xx_err("hal_enter_imps response failed err=%d\n", ret);
+		goto out;
+	}
+
+	wcn36xx_dbg(WCN36XX_DBG_HAL, "Entered idle mode\n");
+out:
+	mutex_unlock(&wcn->hal_mutex);
+	return ret;
+}
+
+int wcn36xx_smd_exit_imps(struct wcn36xx *wcn)
+{
+	struct wcn36xx_hal_exit_imps_req_msg msg_body;
+	int ret;
+
+	mutex_lock(&wcn->hal_mutex);
+	INIT_HAL_MSG(msg_body, WCN36XX_HAL_EXIT_IMPS_REQ);
+
+	PREPARE_HAL_BUF(wcn->hal_buf, msg_body);
+
+	ret = wcn36xx_smd_send_and_wait(wcn, msg_body.header.len);
+	if (ret) {
+		wcn36xx_err("Sending hal_exit_imps failed\n");
+		goto out;
+	}
+	ret = wcn36xx_smd_rsp_status_check(wcn->hal_buf, wcn->hal_rsp_len);
+	if (ret) {
+		wcn36xx_err("hal_exit_imps response failed err=%d\n", ret);
+		goto out;
+	}
+	wcn36xx_dbg(WCN36XX_DBG_HAL, "Exited idle mode\n");
+out:
+	mutex_unlock(&wcn->hal_mutex);
+	return ret;
+}
+
 int wcn36xx_smd_set_power_params(struct wcn36xx *wcn, bool ignore_dtim)
 {
 	struct wcn36xx_hal_set_power_params_req_msg msg_body;
@@ -3082,6 +3135,8 @@ int wcn36xx_smd_rsp_process(struct rpmsg_device *rpdev,
 	case WCN36XX_HAL_GTK_OFFLOAD_RSP:
 	case WCN36XX_HAL_GTK_OFFLOAD_GETINFO_RSP:
 	case WCN36XX_HAL_HOST_RESUME_RSP:
+	case WCN36XX_HAL_ENTER_IMPS_RSP:
+	case WCN36XX_HAL_EXIT_IMPS_RSP:
 		memcpy(wcn->hal_buf, buf, len);
 		wcn->hal_rsp_len = len;
 		complete(&wcn->hal_rsp_compl);

drivers/net/wireless/ath/wcn36xx/smd.h

@@ -163,4 +163,7 @@ int wcn36xx_smd_wlan_host_suspend_ind(struct wcn36xx *wcn);
 
 int wcn36xx_smd_host_resume(struct wcn36xx *wcn);
 
+int wcn36xx_smd_enter_imps(struct wcn36xx *wcn);
+int wcn36xx_smd_exit_imps(struct wcn36xx *wcn);
+
 #endif	/* _SMD_H_ */