wil6210: prevent deep sleep of 60G device in critical paths

In idle times 60G device can enter deep sleep and turn off
its XTAL clock.
Host access triggers the device power-up flow which will hold
the AHB during XTAL stabilization until device switches from
slow-clock to XTAL clock.
This behavior can stall the PCIe bus for some arbitrary period
of time.
In order to prevent this stall, host can vote for High Latency
Access Policy (HALP) before reading from PCIe bus.
This vote will wakeup the device from deep sleep and prevent
deep sleep until unvote is done.

Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/wil6210/wmi.c

@@ -194,6 +194,7 @@ static int __wmi_send(struct wil6210_priv *wil, u16 cmdid, void *buf, u16 len)
 	void __iomem *dst;
 	void __iomem *head = wmi_addr(wil, r->head);
 	uint retry;
+	int rc = 0;
 
 	if (sizeof(cmd) + len > r->entry_size) {
 		wil_err(wil, "WMI size too large: %d bytes, max is %d\n",
@@ -212,6 +213,9 @@ static int __wmi_send(struct wil6210_priv *wil, u16 cmdid, void *buf, u16 len)
 		wil_err(wil, "WMI head is garbage: 0x%08x\n", r->head);
 		return -EINVAL;
 	}
+
+	wil_halp_vote(wil);
+
 	/* read Tx head till it is not busy */
 	for (retry = 5; retry > 0; retry--) {
 		wil_memcpy_fromio_32(&d_head, head, sizeof(d_head));
@@ -221,7 +225,8 @@ static int __wmi_send(struct wil6210_priv *wil, u16 cmdid, void *buf, u16 len)
 	}
 	if (d_head.sync != 0) {
 		wil_err(wil, "WMI head busy\n");
-		return -EBUSY;
+		rc = -EBUSY;
+		goto out;
 	}
 	/* next head */
 	next_head = r->base + ((r->head - r->base + sizeof(d_head)) % r->size);
@@ -230,7 +235,8 @@ static int __wmi_send(struct wil6210_priv *wil, u16 cmdid, void *buf, u16 len)
 	for (retry = 5; retry > 0; retry--) {
 		if (!test_bit(wil_status_fwready, wil->status)) {
 			wil_err(wil, "WMI: cannot send command while FW not ready\n");
-			return -EAGAIN;
+			rc = -EAGAIN;
+			goto out;
 		}
 		r->tail = wil_r(wil, RGF_MBOX +
 				offsetof(struct wil6210_mbox_ctl, tx.tail));
@@ -240,13 +246,15 @@ static int __wmi_send(struct wil6210_priv *wil, u16 cmdid, void *buf, u16 len)
 	}
 	if (next_head == r->tail) {
 		wil_err(wil, "WMI ring full\n");
-		return -EBUSY;
+		rc = -EBUSY;
+		goto out;
 	}
 	dst = wmi_buffer(wil, d_head.addr);
 	if (!dst) {
 		wil_err(wil, "invalid WMI buffer: 0x%08x\n",
 			le32_to_cpu(d_head.addr));
-		return -EINVAL;
+		rc = -EAGAIN;
+		goto out;
 	}
 	cmd.hdr.seq = cpu_to_le16(++wil->wmi_seq);
 	/* set command */
@@ -269,7 +277,9 @@ static int __wmi_send(struct wil6210_priv *wil, u16 cmdid, void *buf, u16 len)
 	wil_w(wil, RGF_USER_USER_ICR + offsetof(struct RGF_ICR, ICS),
 	      SW_INT_MBOX);
 
-	return 0;
+out:
+	wil_halp_unvote(wil);
+	return rc;
 }
 
 int wmi_send(struct wil6210_priv *wil, u16 cmdid, void *buf, u16 len)