ath9k: add support for endian swap of eeprom from platform data

On some devices (especially little-endian ones), the flash EEPROM data
has a different endian, which needs to be detected.
Add a flag to the platform data to allow overriding that behavior

Signed-off-by: Felix Fietkau <[e-mail]>
Signed-off-by: John W. Linville <[e-mail]>

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

···
 {
 	struct ar5416_eeprom_def *eep = &ah->eeprom.def;
 	struct ath_common *common = ath9k_hw_common(ah);
-	u16 *eepdata, temp, magic, magic2;
+	u16 *eepdata, temp, magic;
 	u32 sum = 0, el;
 	bool need_swap = false;
 	int i, addr, size;
···
 		return false;
 	}
 
-	if (!ath9k_hw_use_flash(ah)) {
-		ath_dbg(common, EEPROM, "Read Magic = 0x%04X\n", magic);
+	if (swab16(magic) == AR5416_EEPROM_MAGIC &&
+	    !(ah->ah_flags & AH_NO_EEP_SWAP)) {
+		size = sizeof(struct ar5416_eeprom_def);
+		need_swap = true;
+		eepdata = (u16 *) (&ah->eeprom);
 
-		if (magic != AR5416_EEPROM_MAGIC) {
-			magic2 = swab16(magic);
-
-			if (magic2 == AR5416_EEPROM_MAGIC) {
-				size = sizeof(struct ar5416_eeprom_def);
-				need_swap = true;
-				eepdata = (u16 *) (&ah->eeprom);
-
-				for (addr = 0; addr < size / sizeof(u16); addr++) {
-					temp = swab16(*eepdata);
-					*eepdata = temp;
-					eepdata++;
-				}
-			} else {
-				ath_err(common,
-					"Invalid EEPROM Magic. Endianness mismatch.\n");
-				return -EINVAL;
-			}
+		for (addr = 0; addr < size / sizeof(u16); addr++) {
+			temp = swab16(*eepdata);
+			*eepdata = temp;
+			eepdata++;
 		}
 	}
 

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

···
 #define AH_USE_EEPROM   0x1
 #define AH_UNPLUGGED    0x2 /* The card has been physically removed. */
 #define AH_FASTCC       0x4
+#define AH_NO_EEP_SWAP  0x8 /* Do not swap EEPROM data */
 
 struct ath_hw {
 	struct ath_ops reg_ops;

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

···
 		ah->is_clk_25mhz = pdata->is_clk_25mhz;
 		ah->get_mac_revision = pdata->get_mac_revision;
 		ah->external_reset = pdata->external_reset;
+		if (!pdata->endian_check)
+			ah->ah_flags |= AH_NO_EEP_SWAP;
 	}
 
 	common->ops = &ah->reg_ops;

include/linux/ath9k_platform.h

···
 	u32 gpio_mask;
 	u32 gpio_val;
 
+	bool endian_check;
 	bool is_clk_25mhz;
 	bool tx_gain_buffalo;