diff options
| -rw-r--r-- | arch/mips/dec/time.c | 22 | ||||
| -rw-r--r-- | arch/mips/include/asm/dec/ioasic.h | 2 | ||||
| -rw-r--r-- | arch/mips/kernel/csrc-ioasic.c | 8 |
3 files changed, 27 insertions, 5 deletions
diff --git a/arch/mips/dec/time.c b/arch/mips/dec/time.c index 56ebc7f2bede..1914e56f0d96 100644 --- a/arch/mips/dec/time.c +++ b/arch/mips/dec/time.c @@ -125,12 +125,16 @@ int rtc_mips_set_mmss(unsigned long nowtime) void __init plat_time_init(void) { + int ioasic_clock = 0; u32 start, end; int i = HZ / 8; /* Set up the rate of periodic DS1287 interrupts. */ ds1287_set_base_clock(HZ); + /* On some I/O ASIC systems we have the I/O ASIC's counter. */ + if (IOASIC) + ioasic_clock = dec_ioasic_clocksource_init() == 0; if (cpu_has_counter) { ds1287_timer_state(); while (!ds1287_timer_state()) @@ -147,9 +151,21 @@ void __init plat_time_init(void) mips_hpt_frequency = (end - start) * 8; printk(KERN_INFO "MIPS counter frequency %dHz\n", mips_hpt_frequency); - } else if (IOASIC) - /* For pre-R4k systems we use the I/O ASIC's counter. */ - dec_ioasic_clocksource_init(); + + /* + * All R4k DECstations suffer from the CP0 Count erratum, + * so we can't use the timer as a clock source, and a clock + * event both at a time. An accurate wall clock is more + * important than a high-precision interval timer so only + * use the timer as a clock source, and not a clock event + * if there's no I/O ASIC counter available to serve as a + * clock source. + */ + if (!ioasic_clock) { + init_r4k_clocksource(); + mips_hpt_frequency = 0; + } + } ds1287_clockevent_init(dec_interrupt[DEC_IRQ_RTC]); } diff --git a/arch/mips/include/asm/dec/ioasic.h b/arch/mips/include/asm/dec/ioasic.h index 98badd6bf22d..be4d62a5a10e 100644 --- a/arch/mips/include/asm/dec/ioasic.h +++ b/arch/mips/include/asm/dec/ioasic.h @@ -33,6 +33,6 @@ static inline u32 ioasic_read(unsigned int reg) extern void init_ioasic_irqs(int base); -extern void dec_ioasic_clocksource_init(void); +extern int dec_ioasic_clocksource_init(void); #endif /* __ASM_DEC_IOASIC_H */ diff --git a/arch/mips/kernel/csrc-ioasic.c b/arch/mips/kernel/csrc-ioasic.c index 87e88feb4a25..6cbbf6e106b9 100644 --- a/arch/mips/kernel/csrc-ioasic.c +++ b/arch/mips/kernel/csrc-ioasic.c @@ -37,7 +37,7 @@ static struct clocksource clocksource_dec = { .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; -void __init dec_ioasic_clocksource_init(void) +int __init dec_ioasic_clocksource_init(void) { unsigned int freq; u32 start, end; @@ -56,8 +56,14 @@ void __init dec_ioasic_clocksource_init(void) end = dec_ioasic_hpt_read(&clocksource_dec); freq = (end - start) * 8; + + /* An early revision of the I/O ASIC didn't have the counter. */ + if (!freq) + return -ENXIO; + printk(KERN_INFO "I/O ASIC clock frequency %dHz\n", freq); clocksource_dec.rating = 200 + freq / 10000000; clocksource_register_hz(&clocksource_dec, freq); + return 0; } |