iwlagn: implement layout-agnostic EEPROM reading

The current EEPROM reading code has some layout
assumptions that now turned out to be false with
some newer versions of the EEPROM. Luckily, we
can avoid all such assumptions by using data in
the EEPROM itself, so implement using that.

However, for risk mitigation purposes, keep the
old reading code for current hardware for now.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-eeprom.h b/drivers/net/wireless/iwlwifi/iwl-eeprom.h
index c8566a4..8994b5b 100644
--- a/drivers/net/wireless/iwlwifi/iwl-eeprom.h
+++ b/drivers/net/wireless/iwlwifi/iwl-eeprom.h
@@ -129,6 +129,17 @@
 	s8 max_power_avg;	/* max power (dBm) on this chnl, limit 31 */
 } __packed;
 
+enum iwl_eeprom_enhanced_txpwr_flags {
+	IWL_EEPROM_ENH_TXP_FL_VALID		= BIT(0),
+	IWL_EEPROM_ENH_TXP_FL_BAND_52G		= BIT(1),
+	IWL_EEPROM_ENH_TXP_FL_OFDM		= BIT(2),
+	IWL_EEPROM_ENH_TXP_FL_40MHZ		= BIT(3),
+	IWL_EEPROM_ENH_TXP_FL_HT_AP		= BIT(4),
+	IWL_EEPROM_ENH_TXP_FL_RES1		= BIT(5),
+	IWL_EEPROM_ENH_TXP_FL_RES2		= BIT(6),
+	IWL_EEPROM_ENH_TXP_FL_COMMON_TYPE	= BIT(7),
+};
+
 /**
  * iwl_eeprom_enhanced_txpwr structure
  *    This structure presents the enhanced regulatory tx power limit layout
@@ -197,6 +208,8 @@
 #define EEPROM_LINK_CALIBRATION      (2*0x67)
 #define EEPROM_LINK_PROCESS_ADJST    (2*0x68)
 #define EEPROM_LINK_OTHERS           (2*0x69)
+#define EEPROM_LINK_TXP_LIMIT        (2*0x6a)
+#define EEPROM_LINK_TXP_LIMIT_SIZE   (2*0x6b)
 
 /* agn regulatory - indirect access */
 #define EEPROM_REG_BAND_1_CHANNELS       ((0x08)\
@@ -400,6 +413,8 @@
 #define INDIRECT_CALIBRATION        0x00040000
 #define INDIRECT_PROCESS_ADJST      0x00050000
 #define INDIRECT_OTHERS             0x00060000
+#define INDIRECT_TXP_LIMIT          0x00070000
+#define INDIRECT_TXP_LIMIT_SIZE     0x00080000
 #define INDIRECT_ADDRESS            0x00100000
 
 /* General */