[MIPS] add DECstation I/O ASIC clocksource

Add DECstation I/O ASIC clocksource

Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 65 insertions, 0 deletions

diff --git a/arch/mips/kernel/csrc-ioasic.c b/arch/mips/kernel/csrc-ioasic.c
new file mode 100644
index 000000000000..1d5f63cf8997
--- /dev/null
+++ b/arch/mips/kernel/csrc-ioasic.c
@@ -0,0 +1,65 @@
+/*
+ *  DEC I/O ASIC's counter clocksource
+ *
+ *  Copyright (C) 2008  Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#include <linux/clocksource.h>
+#include <linux/init.h>
+
+#include <asm/ds1287.h>
+#include <asm/time.h>
+#include <asm/dec/ioasic.h>
+#include <asm/dec/ioasic_addrs.h>
+
+static cycle_t dec_ioasic_hpt_read(void)
+{
+	return ioasic_read(IO_REG_FCTR);
+}
+
+static struct clocksource clocksource_dec = {
+	.name		= "dec-ioasic",
+	.read		= dec_ioasic_hpt_read,
+	.mask		= CLOCKSOURCE_MASK(32),
+	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+void __init dec_ioasic_clocksource_init(void)
+{
+	unsigned int freq;
+	u32 start, end;
+	int i = HZ / 10;
+
+
+	while (!ds1287_timer_state())
+		;
+
+	start = dec_ioasic_hpt_read();
+
+	while (i--)
+		while (!ds1287_timer_state())
+			;
+
+	end = dec_ioasic_hpt_read();
+
+	freq = (end - start) * 10;
+	printk(KERN_INFO "I/O ASIC clock frequency %dHz\n", freq);
+
+	clocksource_dec.rating = 200 + freq / 10000000;
+	clocksource_set_clock(&clocksource_dec, freq);
+
+	clocksource_register(&clocksource_dec);
+}