wlcore/wl12xx: Fix wl12xx get_mac error if device is in ELP

At least on wl12xx, reading the MAC after boot can fail with a warning
at drivers/net/wireless/ti/wlcore/sdio.c:78 wl12xx_sdio_raw_read.
The failed call comes from wl12xx_get_mac() that wlcore_nvs_cb() calls
after request_firmware_work_func().

After the error, no wireless interface is created. Reloading the wl12xx
module makes the interface work.

Turns out the wlan controller can be in a low-power ELP state after the
boot from the bootloader or kexec, and needs to be woken up first.

Let's wake the hardware and add a sleep after that similar to
wl12xx_pre_boot() is already doing.

Note that a similar issue could exist for wl18xx, but I have not seen it
so far. And a search for wl18xx_get_mac and wl12xx_sdio_raw_read did not
produce similar errors.

Cc: Carl Philipp Klemm <philipp@uvos.xyz>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210603062814.19464-1-tony@atomide.com

drivers/net/wireless/ti/wl12xx/main.c

@@ -1503,6 +1503,13 @@ static int wl12xx_get_fuse_mac(struct wl1271 *wl)
 	u32 mac1, mac2;
 	int ret;
 
+	/* Device may be in ELP from the bootloader or kexec */
+	ret = wlcore_write32(wl, WL12XX_WELP_ARM_COMMAND, WELP_ARM_COMMAND_VAL);
+	if (ret < 0)
+		goto out;
+
+	usleep_range(500000, 700000);
+
 	ret = wlcore_set_partition(wl, &wl->ptable[PART_DRPW]);
 	if (ret < 0)
 		goto out;