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/sched/loadavg.h>
  13 #include <linux/io.h>
  14
  15 #include <asm/setup.h>
  16 #include <asm/page.h>
  17 #include <asm/prom.h>
  18
  19 static unsigned int base_addr;
  20
  21 void microblaze_heartbeat(void)
  22 {
  23         static unsigned int cnt, period, dist;
  24
  25         if (base_addr) {
  26                 if (cnt == 0 || cnt == dist)
  27                         out_be32(base_addr, 1);
  28                 else if (cnt == 7 || cnt == dist + 7)
  29                         out_be32(base_addr, 0);
  30
  31                 if (++cnt > period) {
  32                         cnt = 0;
  33                         /*
  34                          * The hyperbolic function below modifies the heartbeat
  35                          * period length in dependency of the current (5min)
  36                          * load. It goes through the points f(0)=126, f(1)=86,
  37                          * f(5)=51, f(inf)->30.
  38                          */
  39                         period = ((672 << FSHIFT) / (5 * avenrun[0] +
  40                                                 (7 << FSHIFT))) + 30;
  41                         dist = period / 4;
  42                 }
  43         }
  44 }
  45
  46 void microblaze_setup_heartbeat(void)
  47 {
  48         struct device_node *gpio = NULL;
  49         int *prop;
  50         int j;
  51         const char * const gpio_list[] = {
  52                 "xlnx,xps-gpio-1.00.a",
  53                 NULL
  54         };
  55
  56         for (j = 0; gpio_list[j] != NULL; j++) {
  57                 gpio = of_find_compatible_node(NULL, NULL, gpio_list[j]);
  58                 if (gpio)
  59                         break;
  60         }
  61
  62         if (gpio) {
  63                 base_addr = be32_to_cpup(of_get_property(gpio, "reg", NULL));
  64                 base_addr = (unsigned long) ioremap(base_addr, PAGE_SIZE);
  65                 pr_notice("Heartbeat GPIO at 0x%x\n", base_addr);
  66
  67                 /* GPIO is configured as output */
  68                 prop = (int *) of_get_property(gpio, "xlnx,is-bidir", NULL);
  69                 if (prop)
  70                         out_be32(base_addr + 4, 0);
  71         }
  72 }