rtw88: 8821c: Correct CCK RSSI

Incorrect CCK RSSI may cause periodically scan from upper layer.

8821c phy status does NOT has actual value of CCK power. It provides only
lna and vga index. Driver have to use these indexes to calculate
actual RSSI.

Signed-off-by: Guo-Feng Fan <vincent_fann@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210202055012.8296-3-pkshih@realtek.com

Author: rtlwifi-linux

drivers/net/wireless/realtek/rtw88/rtw8821c.c

@@ -15,6 +15,10 @@
 #include "debug.h"
 #include "bf.h"
 
+static const s8 lna_gain_table_0[8] = {22, 8, -6, -22, -31, -40, -46, -52};
+static const s8 lna_gain_table_1[16] = {10, 6, 2, -2, -6, -10, -14, -17,
+					-20, -24, -28, -31, -34, -37, -40, -44};
+
 static void rtw8821ce_efuse_parsing(struct rtw_efuse *efuse,
 				    struct rtw8821c_efuse *map)
 {
@@ -426,17 +430,49 @@ static void rtw8821c_set_channel(struct rtw_dev *rtwdev, u8 channel, u8 bw,
 	rtw8821c_set_channel_rxdfir(rtwdev, bw);
 }
 
+static s8 get_cck_rx_pwr(struct rtw_dev *rtwdev, u8 lna_idx, u8 vga_idx)
+{
+	struct rtw_efuse *efuse = &rtwdev->efuse;
+	const s8 *lna_gain_table;
+	int lna_gain_table_size;
+	s8 rx_pwr_all = 0;
+	s8 lna_gain = 0;
+
+	if (efuse->rfe_option == 0) {
+		lna_gain_table = lna_gain_table_0;
+		lna_gain_table_size = ARRAY_SIZE(lna_gain_table_0);
+	} else {
+		lna_gain_table = lna_gain_table_1;
+		lna_gain_table_size = ARRAY_SIZE(lna_gain_table_1);
+	}
+
+	if (lna_idx >= lna_gain_table_size) {
+		rtw_info(rtwdev, "incorrect lna index (%d)\n", lna_idx);
+		return -120;
+	}
+
+	lna_gain = lna_gain_table[lna_idx];
+	rx_pwr_all = lna_gain - 2 * vga_idx;
+
+	return rx_pwr_all;
+}
+
 static void query_phy_status_page0(struct rtw_dev *rtwdev, u8 *phy_status,
 				   struct rtw_rx_pkt_stat *pkt_stat)
 {
-	s8 min_rx_power = -120;
-	u8 pwdb = GET_PHY_STAT_P0_PWDB(phy_status);
+	s8 rx_power;
+	u8 lna_idx = 0;
+	u8 vga_idx = 0;
 
-	pkt_stat->rx_power[RF_PATH_A] = pwdb - 100;
+	vga_idx = GET_PHY_STAT_P0_VGA(phy_status);
+	lna_idx = FIELD_PREP(BIT_LNA_H_MASK, GET_PHY_STAT_P0_LNA_H(phy_status)) |
+		  FIELD_PREP(BIT_LNA_L_MASK, GET_PHY_STAT_P0_LNA_L(phy_status));
+	rx_power = get_cck_rx_pwr(rtwdev, lna_idx, vga_idx);
+
+	pkt_stat->rx_power[RF_PATH_A] = rx_power;
 	pkt_stat->rssi = rtw_phy_rf_power_2_rssi(pkt_stat->rx_power, 1);
 	pkt_stat->bw = RTW_CHANNEL_WIDTH_20;
-	pkt_stat->signal_power = max(pkt_stat->rx_power[RF_PATH_A],
-				     min_rx_power);
+	pkt_stat->signal_power = rx_power;
 }
 
 static void query_phy_status_page1(struct rtw_dev *rtwdev, u8 *phy_status,

drivers/net/wireless/realtek/rtw88/rtw8821c.h

@@ -148,6 +148,14 @@ _rtw_write32s_mask(struct rtw_dev *rtwdev, u32 addr, u32 mask, u32 data)
 /* phy status page0 */
 #define GET_PHY_STAT_P0_PWDB(phy_stat)                                         \
 	le32_get_bits(*((__le32 *)(phy_stat) + 0x00), GENMASK(15, 8))
+#define GET_PHY_STAT_P0_VGA(phy_stat)                                          \
+	le32_get_bits(*((__le32 *)(phy_stat) + 0x03), GENMASK(12, 8))
+#define GET_PHY_STAT_P0_LNA_L(phy_stat)                                        \
+	le32_get_bits(*((__le32 *)(phy_stat) + 0x03), GENMASK(15, 13))
+#define GET_PHY_STAT_P0_LNA_H(phy_stat)                                        \
+	le32_get_bits(*((__le32 *)(phy_stat) + 0x03), BIT(23))
+#define BIT_LNA_H_MASK BIT(3)
+#define BIT_LNA_L_MASK GENMASK(2, 0)
 
 /* phy status page1 */
 #define GET_PHY_STAT_P1_PWDB_A(phy_stat)                                       \