ath9k: add external_reset callback to ath9k_platfom_data for AR9330

The patch adds a callback to ath9k_platform_data. If the
callback is provided by the platform code, then it can be
used to hard reset the WMAC device.

The callback is required for doing a hard reset of the AR9330
chips to get them working again after a hang.

Signed-off-by: Gabor Juhos <[e-mail]>
Signed-off-by: John W. Linville <[e-mail]>

drivers/net/wireless/ath/ath9k/hw.c

···
 			rst_flags |= AR_RTC_RC_MAC_COLD;
 	}
 
+	if (AR_SREV_9330(ah)) {
+		int npend = 0;
+		int i;
+
+		/* AR9330 WAR:
+		 * call external reset function to reset WMAC if:
+		 * - doing a cold reset
+		 * - we have pending frames in the TX queues
+		 */
+
+		for (i = 0; i < AR_NUM_QCU; i++) {
+			npend = ath9k_hw_numtxpending(ah, i);
+			if (npend)
+				break;
+		}
+
+		if (ah->external_reset &&
+		    (npend || type == ATH9K_RESET_COLD)) {
+			int reset_err = 0;
+
+			ath_dbg(ath9k_hw_common(ah), ATH_DBG_RESET,
+				"reset MAC via external reset\n");
+
+			reset_err = ah->external_reset();
+			if (reset_err) {
+				ath_err(ath9k_hw_common(ah),
+					"External reset failed, err=%d\n",
+					reset_err);
+				return false;
+			}
+
+			REG_WRITE(ah, AR_RTC_RESET, 1);
+		}
+	}
+
 	REG_WRITE(ah, AR_RTC_RC, rst_flags);
 
 	REGWRITE_BUFFER_FLUSH(ah);

drivers/net/wireless/ath/ath9k/hw.h

···
 
 	bool is_clk_25mhz;
 	int (*get_mac_revision)(void);
+	int (*external_reset)(void);
 };
 
 struct ath_bus_ops {

drivers/net/wireless/ath/ath9k/init.c

···
 		sc->sc_ah->led_pin = pdata->led_pin;
 		ah->is_clk_25mhz = pdata->is_clk_25mhz;
 		ah->get_mac_revision = pdata->get_mac_revision;
+		ah->external_reset = pdata->external_reset;
 	}
 
 	common = ath9k_hw_common(ah);

include/linux/ath9k_platform.h

···
 
 	bool is_clk_25mhz;
 	int (*get_mac_revision)(void);
+	int (*external_reset)(void);
 };
 
 #endif /* _LINUX_ATH9K_PLATFORM_H */