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/config.h>
  12 #include <linux/stddef.h>
  13 #include <linux/sched.h>
  14
  15 void mach_led(int pos, int val);
  16
  17 /* acts like an actual heart beat -- ie thump-thump-pause... */
  18 void heartbeat(void)
  19 {
  20         static unsigned int cnt = 0, period = 0, dist = 0;
  21
  22         if (cnt == 0 || cnt == dist) {
  23                 mach_led(-1, 1);
  24         } else if (cnt == 7 || cnt == dist + 7) {
  25                 mach_led(-1, 0);
  26         }
  27
  28         if (++cnt > period) {
  29                 cnt = 0;
  30
  31                 /*
  32                  * The hyperbolic function below modifies the heartbeat period
  33                  * length in dependency of the current (5min) load. It goes
  34                  * through the points f(0)=126, f(1)=86, f(5)=51, f(inf)->30.
  35                  */
  36                 period = ((672 << FSHIFT) / (5 * avenrun[0] +
  37                                             (7 << FSHIFT))) + 30;
  38                 dist = period / 4;
  39         }
  40 }
  41