microblaze_v8: heartbeat file

Reviewed-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>
Acked-by: John Linn <john.linn@xilinx.com>
Acked-by: John Williams <john.williams@petalogix.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/kernel/heartbeat.c

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu>
+ * Copyright (C) 2007-2009 PetaLogix
+ * Copyright (C) 2006 Atmark Techno, Inc.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/sched.h>
+#include <linux/io.h>
+
+#include <asm/setup.h>
+#include <asm/page.h>
+#include <asm/prom.h>
+
+static unsigned int base_addr;
+
+void heartbeat(void)
+{
+	static unsigned int cnt, period, dist;
+
+	if (base_addr) {
+		if (cnt == 0 || cnt == dist)
+			out_be32(base_addr, 1);
+		else if (cnt == 7 || cnt == dist + 7)
+			out_be32(base_addr, 0);
+
+		if (++cnt > period) {
+			cnt = 0;
+			/*
+			 * The hyperbolic function below modifies the heartbeat
+			 * period length in dependency of the current (5min)
+			 * load. It goes through the points f(0)=126, f(1)=86,
+			 * f(5)=51, f(inf)->30.
+			 */
+			period = ((672 << FSHIFT) / (5 * avenrun[0] +
+						(7 << FSHIFT))) + 30;
+			dist = period / 4;
+		}
+	}
+}
+
+void setup_heartbeat(void)
+{
+	struct device_node *gpio = NULL;
+	int j;
+	char *gpio_list[] = {
+				"xlnx,xps-gpio-1.00.a",
+				"xlnx,opb-gpio-1.00.a",
+				NULL
+			};
+
+	for (j = 0; gpio_list[j] != NULL; j++) {
+		gpio = of_find_compatible_node(NULL, NULL, gpio_list[j]);
+		if (gpio)
+			break;
+	}
+
+	base_addr = *(int *) of_get_property(gpio, "reg", NULL);
+	base_addr = (unsigned long) ioremap(base_addr, PAGE_SIZE);
+	printk(KERN_NOTICE "Heartbeat GPIO at 0x%x\n", base_addr);
+
+	if (*(int *) of_get_property(gpio, "xlnx,is-bidir", NULL))
+		out_be32(base_addr + 4, 0); /* GPIO is configured as output */
+}