[PATCH 2/2] platform/x86: asus-laptop: Add WiMAX rfkill switch for Pegatron Lucid

["Pavel Kossenko (kotekompotek)" <kotekompotek@gmail.com>]

On the Pegatron Lucid the ATK methods ENPR and DAPR enable and disable
a radio selected by an id. The driver exposes ids 0-2 (WLAN, Bluetooth,
WWAN) as the pega-wlan, pega-bt and pega-wwan rfkill switches, but the
DSDT also implements id 6, which drives GPIO27 and the EC bit WMHD:

  If ((Arg0 == 0x06)) { GP27 = Zero; WMHD = Zero; ALED (One) }

The firmware leaves GPIO27 high at boot. On units fitted with an Intel
Centrino Advanced-N + WiMAX 6250 combo card (8086:0087, subsystem
8086:1301) this keeps the whole card in hardware RF-kill, so Wi-Fi is
unusable even though pega-wlan is unblocked:

  iwlwifi 0000:02:00.0: reporting RF_KILL (radio disabled)

The same card works under Windows, presumably because the vendor
utility calls ENPR(6).

Register a "pega-wimax" rfkill switch for id 6. The rfkill core applies
the default unblocked state on registration, which calls ENPR(6) and
releases the card:

  iwlwifi 0000:02:00.0: RF_KILL bit toggled to enable radio.

Assisted-by: Claude Opus 5.5
Signed-off-by: Pavel Kossenko (kotekompotek) <kotekompotek@gmail.com>
---
 drivers/platform/x86/asus-laptop.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/platform/x86/asus-laptop.c b/drivers/platform/x86/asus-laptop.c
index 8e69f02..ef4c2cc 100644
--- a/drivers/platform/x86/asus-laptop.c
+++ b/drivers/platform/x86/asus-laptop.c
@@ -192,6 +192,7 @@ MODULE_PARM_DESC(als_status, "Set the ALS status on boot "
 #define PEGA_WWAN	0x02
 #define PEGA_ALS	0x04
 #define PEGA_ALS_POWER	0x05
+#define PEGA_WIMAX	0x06
 
 #define METHOD_PEGA_READ	"RDLN"
 #define PEGA_READ_ALS_H	0x02
@@ -1454,6 +1455,17 @@ static int pega_rfkill_init(struct asus_laptop *asus)
 
 	ret = pega_rfkill_setup(asus, &asus->wwan, "pega-wwan",
 				PEGA_WWAN, RFKILL_TYPE_WWAN);
+	if (ret)
+		goto exit;
+
+	/*
+	 * The firmware leaves this line asserted at boot. On units fitted
+	 * with an Intel Centrino Advanced-N + WiMAX 6250 combo card it keeps
+	 * the whole card in hardware RF-kill, Wi-Fi included. Registering
+	 * the switch unblocks it by default, which calls ENPR(6).
+	 */
+	ret = pega_rfkill_setup(asus, &asus->wimax, "pega-wimax",
+				PEGA_WIMAX, RFKILL_TYPE_WIMAX);
 
 exit:
 	if (ret)
-- 
2.47.0.windows.2