1 files changed, 131 insertions, 0 deletions

diff --git a/arch/mips/sgi-ip22/ip22-time.c b/arch/mips/sgi-ip22/ip22-time.c
new file mode 100644
index 000000000..045aa89f2
--- /dev/null
+++ b/arch/mips/sgi-ip22/ip22-time.c
@@ -0,0 +1,131 @@
+/*
+ * 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.
+ *
+ * Time operations for IP22 machines. Original code may come from
+ * Ralf Baechle or David S. Miller (sorry guys, i'm really not sure)
+ *
+ * Copyright (C) 2001 by Ladislav Michl
+ * Copyright (C) 2003, 06 Ralf Baechle (ralf@linux-mips.org)
+ */
+#include <linux/bcd.h>
+#include <linux/i8253.h>
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/kernel_stat.h>
+#include <linux/time.h>
+#include <linux/ftrace.h>
+
+#include <asm/cpu.h>
+#include <asm/mipsregs.h>
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/time.h>
+#include <asm/sgialib.h>
+#include <asm/sgi/ioc.h>
+#include <asm/sgi/hpc3.h>
+#include <asm/sgi/ip22.h>
+
+static unsigned long dosample(void)
+{
+        u32 ct0, ct1;
+        u8 msb;
+
+        /* Start the counter. */
+        sgint->tcword = (SGINT_TCWORD_CNT2 | SGINT_TCWORD_CALL |
+                         SGINT_TCWORD_MRGEN);
+        sgint->tcnt2 = SGINT_TCSAMP_COUNTER & 0xff;
+        sgint->tcnt2 = SGINT_TCSAMP_COUNTER >> 8;
+
+        /* Get initial counter invariant */
+        ct0 = read_c0_count();
+
+        /* Latch and spin until top byte of counter2 is zero */
+        do {
+                writeb(SGINT_TCWORD_CNT2 | SGINT_TCWORD_CLAT, &sgint->tcword);
+                (void) readb(&sgint->tcnt2);
+                msb = readb(&sgint->tcnt2);
+                ct1 = read_c0_count();
+        } while (msb);
+
+        /* Stop the counter. */
+        writeb(SGINT_TCWORD_CNT2 | SGINT_TCWORD_CALL | SGINT_TCWORD_MSWST,
+               &sgint->tcword);
+        /*
+         * Return the difference, this is how far the r4k counter increments
+         * for every 1/HZ seconds. We round off the nearest 1 MHz of master
+         * clock (= 1000000 / HZ / 2).
+         */
+
+        return (ct1 - ct0) / (500000/HZ) * (500000/HZ);
+}
+
+/*
+ * Here we need to calibrate the cycle counter to at least be close.
+ */
+__init void plat_time_init(void)
+{
+        unsigned long r4k_ticks[3];
+        unsigned long r4k_tick;
+
+        /*
+         * Figure out the r4k offset, the algorithm is very simple and works in
+         * _all_ cases as long as the 8254 counter register itself works ok (as
+         * an interrupt driving timer it does not because of bug, this is why
+         * we are using the onchip r4k counter/compare register to serve this
+         * purpose, but for r4k_offset calculation it will work ok for us).
+         * There are other very complicated ways of performing this calculation
+         * but this one works just fine so I am not going to futz around. ;-)
+         */
+        printk(KERN_INFO "Calibrating system timer... ");
+        dosample();     /* Prime cache. */
+        dosample();     /* Prime cache. */
+        /* Zero is NOT an option. */
+        do {
+                r4k_ticks[0] = dosample();
+        } while (!r4k_ticks[0]);
+        do {
+                r4k_ticks[1] = dosample();
+        } while (!r4k_ticks[1]);
+
+        if (r4k_ticks[0] != r4k_ticks[1]) {
+                printk("warning: timer counts differ, retrying... ");
+                r4k_ticks[2] = dosample();
+                if (r4k_ticks[2] == r4k_ticks[0]
+                    || r4k_ticks[2] == r4k_ticks[1])
+                        r4k_tick = r4k_ticks[2];
+                else {
+                        printk("disagreement, using average... ");
+                        r4k_tick = (r4k_ticks[0] + r4k_ticks[1]
+                                   + r4k_ticks[2]) / 3;
+                }
+        } else
+                r4k_tick = r4k_ticks[0];
+
+        printk("%d [%d.%04d MHz CPU]\n", (int) r4k_tick,
+                (int) (r4k_tick / (500000 / HZ)),
+                (int) (r4k_tick % (500000 / HZ)));
+
+        mips_hpt_frequency = r4k_tick * HZ;
+
+        if (ip22_is_fullhouse())
+                setup_pit_timer();
+}
+
+/* Generic SGI handler for (spurious) 8254 interrupts */
+void __irq_entry indy_8254timer_irq(void)
+{
+        int irq = SGI_8254_0_IRQ;
+        ULONG cnt;
+        char c;
+
+        irq_enter();
+        kstat_incr_irq_this_cpu(irq);
+        printk(KERN_ALERT "Oops, got 8254 interrupt.\n");
+        ArcRead(0, &c, 1, &cnt);
+        ArcEnterInteractiveMode();
+        irq_exit();
+}