1 files changed, 148 insertions, 0 deletions

diff --git a/arch/mips/sni/time.c b/arch/mips/sni/time.c
new file mode 100644
index 000000000000..20028fc7757e
--- /dev/null
+++ b/arch/mips/sni/time.c
@@ -0,0 +1,148 @@
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/time.h>
+
+#include <asm/sni.h>
+#include <asm/time.h>
+
+#define SNI_CLOCK_TICK_RATE     3686400
+#define SNI_COUNTER2_DIV        64
+#define SNI_COUNTER0_DIV        ((SNI_CLOCK_TICK_RATE / SNI_COUNTER2_DIV) / HZ)
+
+static void sni_a20r_timer_ack(void)
+{
+        *(volatile u8 *)A20R_PT_TIM0_ACK = 0x0; wmb();
+}
+
+/*
+ * a20r platform uses 2 counters to divide the input frequency.
+ * Counter 2 output is connected to Counter 0 & 1 input.
+ */
+static void __init sni_a20r_timer_setup(struct irqaction *irq)
+{
+        *(volatile u8 *)(A20R_PT_CLOCK_BASE + 12) = 0x34; wmb();
+        *(volatile u8 *)(A20R_PT_CLOCK_BASE +  0) = (SNI_COUNTER0_DIV) & 0xff; wmb();
+        *(volatile u8 *)(A20R_PT_CLOCK_BASE +  0) = (SNI_COUNTER0_DIV >> 8) & 0xff; wmb();
+
+        *(volatile u8 *)(A20R_PT_CLOCK_BASE + 12) = 0xb4; wmb();
+        *(volatile u8 *)(A20R_PT_CLOCK_BASE +  8) = (SNI_COUNTER2_DIV) & 0xff; wmb();
+        *(volatile u8 *)(A20R_PT_CLOCK_BASE +  8) = (SNI_COUNTER2_DIV >> 8) & 0xff; wmb();
+
+        setup_irq(SNI_A20R_IRQ_TIMER, irq);
+        mips_timer_ack = sni_a20r_timer_ack;
+}
+
+#define SNI_8254_TICK_RATE        1193182UL
+
+#define SNI_8254_TCSAMP_COUNTER   ((SNI_8254_TICK_RATE / HZ) + 255)
+
+static __init unsigned long dosample(void)
+{
+        u32 ct0, ct1;
+        volatile u8 msb, lsb;
+
+        /* Start the counter. */
+        outb_p (0x34, 0x43);
+        outb_p(SNI_8254_TCSAMP_COUNTER & 0xff, 0x40);
+        outb (SNI_8254_TCSAMP_COUNTER >> 8, 0x40);
+
+        /* Get initial counter invariant */
+        ct0 = read_c0_count();
+
+        /* Latch and spin until top byte of counter0 is zero */
+        do {
+                outb (0x00, 0x43);
+                lsb = inb (0x40);
+                msb = inb (0x40);
+                ct1 = read_c0_count();
+        } while (msb);
+
+        /* Stop the counter. */
+        outb (0x38, 0x43);
+        /*
+         * 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/2)) / (500000/HZ) * (500000/HZ);*/
+        return (ct1 - ct0) / (500000/HZ) * (500000/HZ);
+}
+
+/*
+ * Here we need to calibrate the cycle counter to at least be close.
+ */
+__init void sni_cpu_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;
+}
+
+/*
+ * R4k counter based timer interrupt. Works on RM200-225 and possibly
+ * others but not on RM400
+ */
+static void __init sni_cpu_timer_setup(struct irqaction *irq)
+{
+        setup_irq(SNI_MIPS_IRQ_CPU_TIMER, irq);
+}
+
+void __init plat_timer_setup(struct irqaction *irq)
+{
+        switch (sni_brd_type) {
+        case SNI_BRD_10:
+        case SNI_BRD_10NEW:
+        case SNI_BRD_TOWER_OASIC:
+        case SNI_BRD_MINITOWER:
+                sni_a20r_timer_setup (irq);
+                break;
+
+        case SNI_BRD_PCI_TOWER:
+        case SNI_BRD_RM200:
+        case SNI_BRD_PCI_MTOWER:
+        case SNI_BRD_PCI_DESKTOP:
+        case SNI_BRD_PCI_TOWER_CPLUS:
+        case SNI_BRD_PCI_MTOWER_CPLUS:
+                sni_cpu_timer_setup (irq);
+                break;
+        }
+}