1 files changed, 111 insertions, 0 deletions

diff --git a/drivers/net/igb/igb_main.c b/drivers/net/igb/igb_main.c
index f8c2919bcec0..8b2ba4245090 100644
--- a/drivers/net/igb/igb_main.c
+++ b/drivers/net/igb/igb_main.c
@@ -175,6 +175,54 @@ MODULE_DESCRIPTION("Intel(R) Gigabit Ethernet Network Driver");
 MODULE_LICENSE("GPL");
 MODULE_VERSION(DRV_VERSION);
 
+/**
+ * Scale the NIC clock cycle by a large factor so that
+ * relatively small clock corrections can be added or
+ * substracted at each clock tick. The drawbacks of a
+ * large factor are a) that the clock register overflows
+ * more quickly (not such a big deal) and b) that the
+ * increment per tick has to fit into 24 bits.
+ *
+ * Note that
+ *   TIMINCA = IGB_TSYNC_CYCLE_TIME_IN_NANOSECONDS *
+ *             IGB_TSYNC_SCALE
+ *   TIMINCA += TIMINCA * adjustment [ppm] / 1e9
+ *
+ * The base scale factor is intentionally a power of two
+ * so that the division in %struct timecounter can be done with
+ * a shift.
+ */
+#define IGB_TSYNC_SHIFT (19)
+#define IGB_TSYNC_SCALE (1<<IGB_TSYNC_SHIFT)
+
+/**
+ * The duration of one clock cycle of the NIC.
+ *
+ * @todo This hard-coded value is part of the specification and might change
+ * in future hardware revisions. Add revision check.
+ */
+#define IGB_TSYNC_CYCLE_TIME_IN_NANOSECONDS 16
+
+#if (IGB_TSYNC_SCALE * IGB_TSYNC_CYCLE_TIME_IN_NANOSECONDS) >= (1<<24)
+# error IGB_TSYNC_SCALE and/or IGB_TSYNC_CYCLE_TIME_IN_NANOSECONDS are too large to fit into TIMINCA
+#endif
+
+/**
+ * igb_read_clock - read raw cycle counter (to be used by time counter)
+ */
+static cycle_t igb_read_clock(const struct cyclecounter *tc)
+{
+        struct igb_adapter *adapter =
+                container_of(tc, struct igb_adapter, cycles);
+        struct e1000_hw *hw = &adapter->hw;
+        u64 stamp;
+
+        stamp =  rd32(E1000_SYSTIML);
+        stamp |= (u64)rd32(E1000_SYSTIMH) << 32ULL;
+
+        return stamp;
+}
+
 #ifdef DEBUG
 /**
  * igb_get_hw_dev_name - return device name string
@@ -185,6 +233,29 @@ char *igb_get_hw_dev_name(struct e1000_hw *hw)
         struct igb_adapter *adapter = hw->back;
         return adapter->netdev->name;
 }
+
+/**
+ * igb_get_time_str - format current NIC and system time as string
+ */
+static char *igb_get_time_str(struct igb_adapter *adapter,
+                              char buffer[160])
+{
+        cycle_t hw = adapter->cycles.read(&adapter->cycles);
+        struct timespec nic = ns_to_timespec(timecounter_read(&adapter->clock));
+        struct timespec sys;
+        struct timespec delta;
+        getnstimeofday(&sys);
+
+        delta = timespec_sub(nic, sys);
+
+        sprintf(buffer,
+                "NIC %ld.%09lus, SYS %ld.%09lus, NIC-SYS %lds + %09luns",
+                (long)nic.tv_sec, nic.tv_nsec,
+                (long)sys.tv_sec, sys.tv_nsec,
+                (long)delta.tv_sec, delta.tv_nsec);
+
+        return buffer;
+}
 #endif
 
 /**
@@ -1298,6 +1369,46 @@ static int __devinit igb_probe(struct pci_dev *pdev,
         }
 #endif
 
+        /*
+         * Initialize hardware timer: we keep it running just in case
+         * that some program needs it later on.
+         */
+        memset(&adapter->cycles, 0, sizeof(adapter->cycles));
+        adapter->cycles.read = igb_read_clock;
+        adapter->cycles.mask = CLOCKSOURCE_MASK(64);
+        adapter->cycles.mult = 1;
+        adapter->cycles.shift = IGB_TSYNC_SHIFT;
+        wr32(E1000_TIMINCA,
+             (1<<24) |
+             IGB_TSYNC_CYCLE_TIME_IN_NANOSECONDS * IGB_TSYNC_SCALE);
+#if 0
+        /*
+         * Avoid rollover while we initialize by resetting the time counter.
+         */
+        wr32(E1000_SYSTIML, 0x00000000);
+        wr32(E1000_SYSTIMH, 0x00000000);
+#else
+        /*
+         * Set registers so that rollover occurs soon to test this.
+         */
+        wr32(E1000_SYSTIML, 0x00000000);
+        wr32(E1000_SYSTIMH, 0xFF800000);
+#endif
+        wrfl();
+        timecounter_init(&adapter->clock,
+                         &adapter->cycles,
+                         ktime_to_ns(ktime_get_real()));
+
+#ifdef DEBUG
+        {
+                char buffer[160];
+                printk(KERN_DEBUG
+                        "igb: %s: hw %p initialized timer\n",
+                        igb_get_time_str(adapter, buffer),
+                        &adapter->hw);
+        }
+#endif
+
         dev_info(&pdev->dev, "Intel(R) Gigabit Ethernet Network Connection\n");
         /* print bus type/speed/width info */
         dev_info(&pdev->dev, "%s: (PCIe:%s:%s) %pM\n",