arch/microblaze/kernel/heartbeat.c

   1 /*
   2  * Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu>
   3  * Copyright (C) 2007-2009 PetaLogix
   4  * Copyright (C) 2006 Atmark Techno, Inc.
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License. See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  */
  10
  11 #include <linux/sched.h>
  12 #include <linux/io.h>
  13
  14 #include <asm/setup.h>
  15 #include <asm/page.h>
  16 #include <asm/prom.h>
  17
  18 static unsigned int base_addr;
  19
  20 void heartbeat(void)
  21 {
  22         static unsigned int cnt, period, dist;
  23
  24         if (base_addr) {
  25                 if (cnt == 0 || cnt == dist)
  26                         out_be32(base_addr, 1);
  27                 else if (cnt == 7 || cnt == dist + 7)
  28                         out_be32(base_addr, 0);
  29
  30                 if (++cnt > period) {
  31                         cnt = 0;
  32                         /*
  33                          * The hyperbolic function below modifies the heartbeat
  34                          * period length in dependency of the current (5min)
  35                          * load. It goes through the points f(0)=126, f(1)=86,
  36                          * f(5)=51, f(inf)->30.
  37                          */
  38                         period = ((672 << FSHIFT) / (5 * avenrun[0] +
  39                                                 (7 << FSHIFT))) + 30;
  40                         dist = period / 4;
  41                 }
  42         }
  43 }
  44
  45 void setup_heartbeat(void)
  46 {
  47         struct device_node *gpio = NULL;
  48         int *prop;
  49         int j;
  50         const char * const gpio_list[] = {
  51                 "xlnx,xps-gpio-1.00.a",
  52                 NULL
  53         };
  54
  55         for (j = 0; gpio_list[j] != NULL; j++) {
  56                 gpio = of_find_compatible_node(NULL, NULL, gpio_list[j]);
  57                 if (gpio)
  58                         break;
  59         }
  60
  61         if (gpio) {
  62                 base_addr = be32_to_cpup(of_get_property(gpio, "reg", NULL));
  63                 base_addr = (unsigned long) ioremap(base_addr, PAGE_SIZE);
  64                 printk(KERN_NOTICE "Heartbeat GPIO at 0x%x\n", base_addr);
  65
  66                 /* GPIO is configured as output */
  67                 prop = (int *) of_get_property(gpio, "xlnx,is-bidir", NULL);
  68                 if (prop)
  69                         out_be32(base_addr + 4, 0);
  70         }
  71 }