ath9k_hw: Add a function to read sqsum_dvc.

Add a function to observe the delta VC of BB_PLL.
For a good chip, the sqsum_dvc is below 2000.
Signed-off-by: Vivek Natarajan <vnatarajan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -668,6 +668,19 @@ static void ath9k_hw_init_qos(struct ath_hw *ah)
 	REGWRITE_BUFFER_FLUSH(ah);
 }
 
+unsigned long ar9003_get_pll_sqsum_dvc(struct ath_hw *ah)
+{
+		REG_WRITE(ah, PLL3, (REG_READ(ah, PLL3) & ~(PLL3_DO_MEAS_MASK)));
+		udelay(100);
+		REG_WRITE(ah, PLL3, (REG_READ(ah, PLL3) | PLL3_DO_MEAS_MASK));
+
+		while ((REG_READ(ah, PLL4) & PLL4_MEAS_DONE) == 0)
+			udelay(100);
+
+		return (REG_READ(ah, PLL3) & SQSUM_DVC_MASK) >> 3;
+}
+EXPORT_SYMBOL(ar9003_get_pll_sqsum_dvc);
+
 static void ath9k_hw_init_pll(struct ath_hw *ah,
 			      struct ath9k_channel *chan)
 {

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

@@ -928,6 +928,7 @@ void ath9k_hw_settsf64(struct ath_hw *ah, u64 tsf64);
 void ath9k_hw_reset_tsf(struct ath_hw *ah);
 void ath9k_hw_set_tsfadjust(struct ath_hw *ah, u32 setting);
 void ath9k_hw_init_global_settings(struct ath_hw *ah);
+unsigned long ar9003_get_pll_sqsum_dvc(struct ath_hw *ah);
 void ath9k_hw_set11nmac2040(struct ath_hw *ah);
 void ath9k_hw_beaconinit(struct ath_hw *ah, u32 next_beacon, u32 beacon_period);
 void ath9k_hw_set_sta_beacon_timers(struct ath_hw *ah,

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

@@ -1129,6 +1129,12 @@ enum {
 #define AR_RTC_PLL_CLKSEL       0x00000300
 #define AR_RTC_PLL_CLKSEL_S     8
 
+#define PLL3 0x16188
+#define PLL3_DO_MEAS_MASK 0x40000000
+#define PLL4 0x1618c
+#define PLL4_MEAS_DONE    0x8
+#define SQSUM_DVC_MASK 0x007ffff8
+
 #define AR_RTC_RESET \
 	((AR_SREV_9100(ah)) ? (AR_RTC_BASE + 0x0040) : 0x7040)
 #define AR_RTC_RESET_EN		(0x00000001)