[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>

arch/mips/Kconfig

@@ -82,6 +82,7 @@ config MACH_DECSTATION
 	bool "DECstations"
 	select BOOT_ELF32
 	select CEVT_R4K
+	select CSRC_IOASIC
 	select CSRC_R4K
 	select CPU_DADDI_WORKAROUNDS if 64BIT
 	select CPU_R4000_WORKAROUNDS if 64BIT
@@ -784,6 +785,9 @@ config CEVT_TXX9
 config CSRC_BCM1480
 	bool
 
+config CSRC_IOASIC
+	bool
+
 config CSRC_R4K
 	bool
 

arch/mips/dec/time.c

@@ -165,7 +165,7 @@ void __init plat_time_init(void)
 
 	if (!cpu_has_counter && IOASIC)
 		/* For pre-R4k systems we use the I/O ASIC's counter.  */
-		clocksource_mips.read = dec_ioasic_hpt_read;
+		dec_ioasic_clocksource_init();
 
 	/* Set up the rate of periodic DS1287 interrupts.  */
 	CMOS_WRITE(RTC_REF_CLCK_32KHZ | (16 - __ffs(HZ)), RTC_REG_A);

arch/mips/kernel/Makefile

@@ -14,6 +14,7 @@ obj-$(CONFIG_CEVT_GT641XX)	+= cevt-gt641xx.o
 obj-$(CONFIG_CEVT_SB1250)	+= cevt-sb1250.o
 obj-$(CONFIG_CEVT_TXX9)		+= cevt-txx9.o
 obj-$(CONFIG_CSRC_BCM1480)	+= csrc-bcm1480.o
+obj-$(CONFIG_CSRC_IOASIC)	+= csrc-ioasic.o
 obj-$(CONFIG_CSRC_R4K)		+= csrc-r4k.o
 obj-$(CONFIG_CSRC_SB1250)	+= csrc-sb1250.o
 obj-$(CONFIG_SYNC_R4K)		+= sync-r4k.o

arch/mips/kernel/csrc-ioasic.c

+/*
+ *  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);
+}

include/asm-mips/dec/ioasic.h

@@ -33,4 +33,6 @@ static inline u32 ioasic_read(unsigned int reg)
 
 extern void init_ioasic_irqs(int base);
 
+extern void dec_ioasic_clocksource_init(void);
+
 #endif /* __ASM_DEC_IOASIC_H */