arch/sh64/kernel/led.c

   1 /*
   2  * arch/sh64/kernel/led.c
   3  *
   4  * Copyright (C) 2002 Stuart Menefy <stuart.menefy@st.com>
   5  *
   6  * May be copied or modified under the terms of the GNU General Public
   7  * License.  See linux/COPYING for more information.
   8  *
   9  * Flash the LEDs
  10  */
  11 #include <linux/stddef.h>
  12 #include <linux/sched.h>
  13
  14 void mach_led(int pos, int val);
  15
  16 /* acts like an actual heart beat -- ie thump-thump-pause... */
  17 void heartbeat(void)
  18 {
  19         static unsigned int cnt = 0, period = 0, dist = 0;
  20
  21         if (cnt == 0 || cnt == dist) {
  22                 mach_led(-1, 1);
  23         } else if (cnt == 7 || cnt == dist + 7) {
  24                 mach_led(-1, 0);
  25         }
  26
  27         if (++cnt > period) {
  28                 cnt = 0;
  29
  30                 /*
  31                  * The hyperbolic function below modifies the heartbeat period
  32                  * length in dependency of the current (5min) load. It goes
  33                  * through the points f(0)=126, f(1)=86, f(5)=51, f(inf)->30.
  34                  */
  35                 period = ((672 << FSHIFT) / (5 * avenrun[0] +
  36                                             (7 << FSHIFT))) + 30;
  37                 dist = period / 4;
  38         }
  39 }
  40