p54: enhance rssi->dBm database import

This patch fixes several shortcomings of the
previous implementation. Features of the
rewrite include:

 * handles undocumented "0x0000" word at the
   start of the frequency table.
   (Affected some early? DELL 1450 USB devices
    and my Symbol 5GHz miniPCI card.)

 * supports more than just one reference point
   per band. (Also needed for the Symbol card.)

 * ships with default values in case the eeprom
   data is damaged, absent or unsupported.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/p54/p54.h b/drivers/net/wireless/p54/p54.h
index 43a3b2e..f951c8f 100644
--- a/drivers/net/wireless/p54/p54.h
+++ b/drivers/net/wireless/p54/p54.h
@@ -116,7 +116,8 @@
 	__le16 txop;
 } __packed;
 
-struct p54_rssi_linear_approximation {
+struct p54_rssi_db_entry {
+	u16 freq;
 	s16 mul;
 	s16 add;
 	s16 longbow_unkn;
@@ -197,13 +198,14 @@
 	u8 rx_diversity_mask;
 	u8 tx_diversity_mask;
 	unsigned int output_power;
+	struct p54_rssi_db_entry *cur_rssi;
 	int noise;
 	/* calibration, output power limit and rssi<->dBm conversation data */
 	struct pda_iq_autocal_entry *iq_autocal;
 	unsigned int iq_autocal_len;
 	struct p54_cal_database *curve_data;
 	struct p54_cal_database *output_limit;
-	struct p54_rssi_linear_approximation rssical_db[IEEE80211_NUM_BANDS];
+	struct p54_cal_database *rssi_db;
 	struct ieee80211_supported_band *band_table[IEEE80211_NUM_BANDS];
 
 	/* BBP/MAC state */