bfin_mac: replace sys time stamps with raw ones instead.

This patch replaces the sys time stamps and timecompare code with simple
raw hardware time stamps in nanosecond resolution. The only tricky bit is
to find a PTP Hardware Clock period slower than the input clock period
and a power of two.

Compile tested only.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Tested-by: Bob Liu <lliubbo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/adi/bfin_mac.c b/drivers/net/ethernet/adi/bfin_mac.c
index 2349abb..885fa80 100644
--- a/drivers/net/ethernet/adi/bfin_mac.c
+++ b/drivers/net/ethernet/adi/bfin_mac.c
@@ -555,7 +555,7 @@
 	info->so_timestamping =
 		SOF_TIMESTAMPING_TX_HARDWARE |
 		SOF_TIMESTAMPING_RX_HARDWARE |
-		SOF_TIMESTAMPING_SYS_HARDWARE;
+		SOF_TIMESTAMPING_RAW_HARDWARE;
 	info->phc_index = -1;
 	info->tx_types =
 		(1 << HWTSTAMP_TX_OFF) |
@@ -653,6 +653,20 @@
 #ifdef CONFIG_BFIN_MAC_USE_HWSTAMP
 #define bfin_mac_hwtstamp_is_none(cfg) ((cfg) == HWTSTAMP_FILTER_NONE)
 
+static u32 bfin_select_phc_clock(u32 input_clk, unsigned int *shift_result)
+{
+	u32 ipn = 1000000000UL / input_clk;
+	u32 ppn = 1;
+	unsigned int shift = 0;
+
+	while (ppn <= ipn) {
+		ppn <<= 1;
+		shift++;
+	}
+	*shift_result = shift;
+	return 1000000000UL / ppn;
+}
+
 static int bfin_mac_hwtstamp_ioctl(struct net_device *netdev,
 		struct ifreq *ifr, int cmd)
 {
@@ -802,19 +816,7 @@
 		bfin_read_EMAC_PTP_TXSNAPLO();
 		bfin_read_EMAC_PTP_TXSNAPHI();
 
-		/*
-		 * Set registers so that rollover occurs soon to test this.
-		 */
-		bfin_write_EMAC_PTP_TIMELO(0x00000000);
-		bfin_write_EMAC_PTP_TIMEHI(0xFF800000);
-
 		SSYNC();
-
-		lp->compare.last_update = 0;
-		timecounter_init(&lp->clock,
-				&lp->cycles,
-				ktime_to_ns(ktime_get_real()));
-		timecompare_update(&lp->compare, 0);
 	}
 
 	lp->stamp_cfg = config;
@@ -822,15 +824,6 @@
 		-EFAULT : 0;
 }
 
-static void bfin_dump_hwtamp(char *s, ktime_t *hw, ktime_t *ts, struct timecompare *cmp)
-{
-	ktime_t sys = ktime_get_real();
-
-	pr_debug("%s %s hardware:%d,%d transform system:%d,%d system:%d,%d, cmp:%lld, %lld\n",
-			__func__, s, hw->tv.sec, hw->tv.nsec, ts->tv.sec, ts->tv.nsec, sys.tv.sec,
-			sys.tv.nsec, cmp->offset, cmp->skew);
-}
-
 static void bfin_tx_hwtstamp(struct net_device *netdev, struct sk_buff *skb)
 {
 	struct bfin_mac_local *lp = netdev_priv(netdev);
@@ -861,15 +854,9 @@
 			regval = bfin_read_EMAC_PTP_TXSNAPLO();
 			regval |= (u64)bfin_read_EMAC_PTP_TXSNAPHI() << 32;
 			memset(&shhwtstamps, 0, sizeof(shhwtstamps));
-			ns = timecounter_cyc2time(&lp->clock,
-					regval);
-			timecompare_update(&lp->compare, ns);
+			ns = regval << lp->shift;
 			shhwtstamps.hwtstamp = ns_to_ktime(ns);
-			shhwtstamps.syststamp =
-				timecompare_transform(&lp->compare, ns);
 			skb_tstamp_tx(skb, &shhwtstamps);
-
-			bfin_dump_hwtamp("TX", &shhwtstamps.hwtstamp, &shhwtstamps.syststamp, &lp->compare);
 		}
 	}
 }
@@ -892,51 +879,25 @@
 
 	regval = bfin_read_EMAC_PTP_RXSNAPLO();
 	regval |= (u64)bfin_read_EMAC_PTP_RXSNAPHI() << 32;
-	ns = timecounter_cyc2time(&lp->clock, regval);
-	timecompare_update(&lp->compare, ns);
+	ns = regval << lp->shift;
 	memset(shhwtstamps, 0, sizeof(*shhwtstamps));
 	shhwtstamps->hwtstamp = ns_to_ktime(ns);
-	shhwtstamps->syststamp = timecompare_transform(&lp->compare, ns);
-
-	bfin_dump_hwtamp("RX", &shhwtstamps->hwtstamp, &shhwtstamps->syststamp, &lp->compare);
 }
 
-/*
- * bfin_read_clock - read raw cycle counter (to be used by time counter)
- */
-static cycle_t bfin_read_clock(const struct cyclecounter *tc)
-{
-	u64 stamp;
-
-	stamp =  bfin_read_EMAC_PTP_TIMELO();
-	stamp |= (u64)bfin_read_EMAC_PTP_TIMEHI() << 32ULL;
-
-	return stamp;
-}
-
-#define PTP_CLK 25000000
-
 static void bfin_mac_hwtstamp_init(struct net_device *netdev)
 {
 	struct bfin_mac_local *lp = netdev_priv(netdev);
-	u64 append;
+	u64 addend;
+	u32 input_clk, phc_clk;
 
 	/* Initialize hardware timer */
-	append = PTP_CLK * (1ULL << 32);
-	do_div(append, get_sclk());
-	bfin_write_EMAC_PTP_ADDEND((u32)append);
+	input_clk = get_sclk();
+	phc_clk = bfin_select_phc_clock(input_clk, &lp->shift);
+	addend = phc_clk * (1ULL << 32);
+	do_div(addend, input_clk);
+	bfin_write_EMAC_PTP_ADDEND((u32)addend);
 
-	memset(&lp->cycles, 0, sizeof(lp->cycles));
-	lp->cycles.read = bfin_read_clock;
-	lp->cycles.mask = CLOCKSOURCE_MASK(64);
-	lp->cycles.mult = 1000000000 / PTP_CLK;
-	lp->cycles.shift = 0;
-
-	/* Synchronize our NIC clock against system wall clock */
-	memset(&lp->compare, 0, sizeof(lp->compare));
-	lp->compare.source = &lp->clock;
-	lp->compare.target = ktime_get_real;
-	lp->compare.num_samples = 10;
+	lp->addend = addend;
 
 	/* Initialize hwstamp config */
 	lp->stamp_cfg.rx_filter = HWTSTAMP_FILTER_NONE;