sch: make htb_rate_cfg and functions around that generic

[platform/adaptation/renesas_rcar/renesas_kernel.git] / net / sched / sch_generic.c

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 5d81a44..ffad481 100644 (file)
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -25,6 +25,7 @@
 #include <linux/rcupdate.h>
 #include <linux/list.h>
 #include <linux/slab.h>
+#include <net/sch_generic.h>
 #include <net/pkt_sched.h>
 #include <net/dst.h>
 
@@ -896,3 +897,39 @@ void dev_shutdown(struct net_device *dev)
 
        WARN_ON(timer_pending(&dev->watchdog_timer));
 }
+
+void psched_ratecfg_precompute(struct psched_ratecfg *r, u32 rate)
+{
+       u64 factor;
+       u64 mult;
+       int shift;
+
+       r->rate_bps = rate << 3;
+       r->shift = 0;
+       r->mult = 1;
+       /*
+        * Calibrate mult, shift so that token counting is accurate
+        * for smallest packet size (64 bytes).  Token (time in ns) is
+        * computed as (bytes * 8) * NSEC_PER_SEC / rate_bps.  It will
+        * work as long as the smallest packet transfer time can be
+        * accurately represented in nanosec.
+        */
+       if (r->rate_bps > 0) {
+               /*
+                * Higher shift gives better accuracy.  Find the largest
+                * shift such that mult fits in 32 bits.
+                */
+               for (shift = 0; shift < 16; shift++) {
+                       r->shift = shift;
+                       factor = 8LLU * NSEC_PER_SEC * (1 << r->shift);
+                       mult = div64_u64(factor, r->rate_bps);
+                       if (mult > UINT_MAX)
+                               break;
+               }
+
+               r->shift = shift - 1;
+               factor = 8LLU * NSEC_PER_SEC * (1 << r->shift);
+               r->mult = div64_u64(factor, r->rate_bps);
+       }
+}
+EXPORT_SYMBOL(psched_ratecfg_precompute);