LXR linux/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
  18static unsigned int base_addr;
  19
  20void 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
  45void setup_heartbeat(void)
  46{
  47        struct device_node *gpio = NULL;
  48        int j;
  49        char *gpio_list[] = {
  50                                "xlnx,xps-gpio-1.00.a",
  51                                "xlnx,opb-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        base_addr = *(int *) of_get_property(gpio, "reg", NULL);
  62        base_addr = (unsigned long) ioremap(base_addr, PAGE_SIZE);
  63        printk(KERN_NOTICE "Heartbeat GPIO at 0x%x\n", base_addr);
  64
  65        if (*(int *) of_get_property(gpio, "xlnx,is-bidir", NULL))
  66                out_be32(base_addr + 4, 0); /* GPIO is configured as output */
  67}
  68