Support for MIPSsim, the cycle accurate MIPS simulator.

    
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 215 insertions, 0 deletions

diff --git a/arch/mips/mips-boards/sim/sim_time.c b/arch/mips/mips-boards/sim/sim_time.c
new file mode 100644
index 000000000000..18b968c696d1
--- /dev/null
+++ b/arch/mips/mips-boards/sim/sim_time.c
@@ -0,0 +1,215 @@
+#include <linux/types.h>
+#include <linux/config.h>
+#include <linux/init.h>
+#include <linux/kernel_stat.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+
+#include <asm/mipsregs.h>
+#include <asm/ptrace.h>
+#include <asm/hardirq.h>
+#include <asm/div64.h>
+#include <asm/cpu.h>
+#include <asm/time.h>
+
+#include <linux/interrupt.h>
+#include <linux/mc146818rtc.h>
+#include <linux/timex.h>
+#include <asm/mipsregs.h>
+#include <asm/ptrace.h>
+#include <asm/hardirq.h>
+#include <asm/irq.h>
+#include <asm/div64.h>
+#include <asm/cpu.h>
+#include <asm/time.h>
+#include <asm/mc146818-time.h>
+#include <asm/msc01_ic.h>
+
+#include <asm/mips-boards/generic.h>
+#include <asm/mips-boards/prom.h>
+#include <asm/mips-boards/simint.h>
+#include <asm/mc146818-time.h>
+#include <asm/smp.h>
+
+
+unsigned long cpu_khz;
+
+extern asmlinkage void ll_local_timer_interrupt(int irq, struct pt_regs *regs);
+
+irqreturn_t sim_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+#ifdef CONFIG_SMP
+        int cpu = smp_processor_id();
+
+        /*
+         * CPU 0 handles the global timer interrupt job
+         * resets count/compare registers to trigger next timer int.
+         */
+#ifndef CONFIG_MIPS_MT_SMTC
+        if (cpu == 0) {
+                timer_interrupt(irq, dev_id, regs);
+        }
+        else {
+                /* Everyone else needs to reset the timer int here as
+                   ll_local_timer_interrupt doesn't */
+                /*
+                 * FIXME: need to cope with counter underflow.
+                 * More support needs to be added to kernel/time for
+                 * counter/timer interrupts on multiple CPU's
+                 */
+                write_c0_compare (read_c0_count() + ( mips_hpt_frequency/HZ));
+        }
+#else /* SMTC */
+        /*
+         *  In SMTC system, one Count/Compare set exists per VPE.
+         *  Which TC within a VPE gets the interrupt is essentially
+         *  random - we only know that it shouldn't be one with
+         *  IXMT set. Whichever TC gets the interrupt needs to
+         *  send special interprocessor interrupts to the other
+         *  TCs to make sure that they schedule, etc.
+         *
+         *  That code is specific to the SMTC kernel, not to
+         *  the simulation platform, so it's invoked from
+         *  the general MIPS timer_interrupt routine.
+         *
+         * We have a problem in that the interrupt vector code
+         * had to turn off the timer IM bit to avoid redundant
+         * entries, but we may never get to mips_cpu_irq_end
+         * to turn it back on again if the scheduler gets
+         * involved.  So we clear the pending timer here,
+         * and re-enable the mask...
+         */
+
+        int vpflags = dvpe();
+        write_c0_compare (read_c0_count() - 1);
+        clear_c0_cause(0x100 << MIPSCPU_INT_CPUCTR);
+        set_c0_status(0x100 << MIPSCPU_INT_CPUCTR);
+        irq_enable_hazard();
+        evpe(vpflags);
+
+        if(cpu_data[cpu].vpe_id == 0) timer_interrupt(irq, dev_id, regs);
+        else write_c0_compare (read_c0_count() + ( mips_hpt_frequency/HZ));
+        smtc_timer_broadcast(cpu_data[cpu].vpe_id);
+
+#endif /* CONFIG_MIPS_MT_SMTC */
+
+        /*
+         * every CPU should do profiling and process accounting
+         */
+        local_timer_interrupt (irq, dev_id, regs);
+        return IRQ_HANDLED;
+#else
+        return timer_interrupt (irq, dev_id, regs);
+#endif
+}
+
+
+
+/*
+ * Estimate CPU frequency.  Sets mips_counter_frequency as a side-effect
+ */
+static unsigned int __init estimate_cpu_frequency(void)
+{
+        unsigned int prid = read_c0_prid() & 0xffff00;
+        unsigned int count;
+
+#if 1
+        /*
+         * hardwire the board frequency to 12MHz.
+         */
+
+        if ((prid == (PRID_COMP_MIPS | PRID_IMP_20KC)) ||
+            (prid == (PRID_COMP_MIPS | PRID_IMP_25KF)))
+                count = 12000000;
+        else
+                count =  6000000;
+#else
+        unsigned int flags;
+
+        local_irq_save(flags);
+
+        /* Start counter exactly on falling edge of update flag */
+        while (CMOS_READ(RTC_REG_A) & RTC_UIP);
+        while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
+
+        /* Start r4k counter. */
+        write_c0_count(0);
+
+        /* Read counter exactly on falling edge of update flag */
+        while (CMOS_READ(RTC_REG_A) & RTC_UIP);
+        while (!(CMOS_READ(RTC_REG_A) & RTC_UIP));
+
+        count = read_c0_count();
+
+        /* restore interrupts */
+        local_irq_restore(flags);
+#endif
+
+        mips_hpt_frequency = count;
+
+        if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
+            (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
+                count *= 2;
+
+        count += 5000;    /* round */
+        count -= count%10000;
+
+        return count;
+}
+
+void __init sim_time_init(void)
+{
+        unsigned int est_freq, flags;
+
+        local_irq_save(flags);
+
+
+        /* Set Data mode - binary. */
+        CMOS_WRITE(CMOS_READ(RTC_CONTROL) | RTC_DM_BINARY, RTC_CONTROL);
+
+
+        est_freq = estimate_cpu_frequency ();
+
+        printk("CPU frequency %d.%02d MHz\n", est_freq/1000000,
+               (est_freq%1000000)*100/1000000);
+
+        cpu_khz = est_freq / 1000;
+
+        local_irq_restore(flags);
+}
+
+static int mips_cpu_timer_irq;
+
+static void mips_timer_dispatch (struct pt_regs *regs)
+{
+        do_IRQ (mips_cpu_timer_irq, regs);
+}
+
+
+void __init sim_timer_setup(struct irqaction *irq)
+{
+        if (cpu_has_veic) {
+                set_vi_handler(MSC01E_INT_CPUCTR, mips_timer_dispatch);
+                mips_cpu_timer_irq = MSC01E_INT_BASE + MSC01E_INT_CPUCTR;
+        }
+        else {
+                if (cpu_has_vint)
+                        set_vi_handler(MIPSCPU_INT_CPUCTR, mips_timer_dispatch);
+                mips_cpu_timer_irq = MIPSCPU_INT_BASE + MIPSCPU_INT_CPUCTR;
+        }
+
+        /* we are using the cpu counter for timer interrupts */
+        irq->handler = sim_timer_interrupt;
+        setup_irq(mips_cpu_timer_irq, irq);
+
+#ifdef CONFIG_SMP
+        /* irq_desc(riptor) is a global resource, when the interrupt overlaps
+           on seperate cpu's the first one tries to handle the second interrupt.
+           The effect is that the int remains disabled on the second cpu.
+           Mark the interrupt with IRQ_PER_CPU to avoid any confusion */
+        irq_desc[mips_cpu_timer_irq].status |= IRQ_PER_CPU;
+#endif
+
+        /* to generate the first timer interrupt */
+        write_c0_compare(read_c0_count() + (mips_hpt_frequency/HZ));
+}