diff options
Diffstat (limited to 'arch/mips/mipssim/sim_time.c')
| -rw-r--r-- | arch/mips/mipssim/sim_time.c | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/arch/mips/mipssim/sim_time.c b/arch/mips/mipssim/sim_time.c new file mode 100644 index 00000000000..874a18e8ac2 --- /dev/null +++ b/arch/mips/mipssim/sim_time.c @@ -0,0 +1,200 @@ +#include <linux/types.h> +#include <linux/init.h> +#include <linux/kernel_stat.h> +#include <linux/sched.h> +#include <linux/spinlock.h> +#include <linux/interrupt.h> +#include <linux/mc146818rtc.h> +#include <linux/mipsregs.h> +#include <linux/smp.h> +#include <linux/timex.h> + +#include <asm/hardirq.h> +#include <asm/div64.h> +#include <asm/cpu.h> +#include <asm/time.h> +#include <asm/irq.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> + + +unsigned long cpu_khz; + +irqreturn_t sim_timer_interrupt(int irq, void *dev_id) +{ +#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); + } 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 << cp0_compare_irq); + set_c0_status(0x100 << cp0_compare_irq); + irq_enable_hazard(); + evpe(vpflags); + + if (cpu_data[cpu].vpe_id == 0) + timer_interrupt(irq, dev_id); + 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); + + return IRQ_HANDLED; +#else + return timer_interrupt (irq, dev_id); +#endif +} + + + +/* + * Estimate CPU frequency. Sets mips_hpt_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(KERN_INFO "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(void) +{ + do_IRQ(mips_cpu_timer_irq); +} + + +void __init plat_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(cp0_compare_irq, mips_timer_dispatch); + mips_cpu_timer_irq = MIPS_CPU_IRQ_BASE + cp0_compare_irq; + } + + /* 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].flags |= IRQ_PER_CPU; + set_irq_handler(mips_cpu_timer_irq, handle_percpu_irq); +#endif +} |