arch/sh/boards/overdrive/led.c

   1 /*
   2  * linux/arch/sh/overdrive/led.c
   3  *
   4  * Copyright (C) 1999 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  * This file contains an Overdrive specific LED feature.
  10  */
  11
  12 #include <linux/config.h>
  13 #include <asm/system.h>
  14 #include <asm/io.h>
  15 #include <asm/overdrive/overdrive.h>
  16
  17 static void mach_led(int position, int value)
  18 {
  19         unsigned long flags;
  20         unsigned long reg;
  21
  22         local_irq_save(flags);
  23
  24         reg = readl(OVERDRIVE_CTRL);
  25         if (value) {
  26                 reg |= (1<<3);
  27         } else {
  28                 reg &= ~(1<<3);
  29         }
  30         writel(reg, OVERDRIVE_CTRL);
  31
  32         local_irq_restore(flags);
  33 }
  34
  35 #ifdef CONFIG_HEARTBEAT
  36
  37 #include <linux/sched.h>
  38
  39 /* acts like an actual heart beat -- ie thump-thump-pause... */
  40 void heartbeat_od(void)
  41 {
  42         static unsigned cnt = 0, period = 0, dist = 0;
  43
  44         if (cnt == 0 || cnt == dist)
  45                 mach_led( -1, 1);
  46         else if (cnt == 7 || cnt == dist+7)
  47                 mach_led( -1, 0);
  48
  49         if (++cnt > period) {
  50                 cnt = 0;
  51                 /* The hyperbolic function below modifies the heartbeat period
  52                  * length in dependency of the current (5min) load. It goes
  53                  * through the points f(0)=126, f(1)=86, f(5)=51,
  54                  * f(inf)->30. */
  55                 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30;
  56                 dist = period / 4;
  57         }
  58 }
  59 #endif /* CONFIG_HEARTBEAT */