diff options
Diffstat (limited to 'arch/x86/kernel/mfgpt_32.c')
| -rw-r--r-- | arch/x86/kernel/mfgpt_32.c | 30 |
1 files changed, 23 insertions, 7 deletions
diff --git a/arch/x86/kernel/mfgpt_32.c b/arch/x86/kernel/mfgpt_32.c index 0ab680f2d9db..219f86eb6123 100644 --- a/arch/x86/kernel/mfgpt_32.c +++ b/arch/x86/kernel/mfgpt_32.c @@ -63,6 +63,21 @@ static int __init mfgpt_disable(char *s) } __setup("nomfgpt", mfgpt_disable); +/* Reset the MFGPT timers. This is required by some broken BIOSes which already + * do the same and leave the system in an unstable state. TinyBIOS 0.98 is + * affected at least (0.99 is OK with MFGPT workaround left to off). + */ +static int __init mfgpt_fix(char *s) +{ + u32 val, dummy; + + /* The following udocumented bit resets the MFGPT timers */ + val = 0xFF; dummy = 0; + wrmsr(0x5140002B, val, dummy); + return 1; +} +__setup("mfgptfix", mfgpt_fix); + /* * Check whether any MFGPTs are available for the kernel to use. In most * cases, firmware that uses AMD's VSA code will claim all timers during @@ -278,12 +293,12 @@ static int mfgpt_next_event(unsigned long delta, struct clock_event_device *evt) static irqreturn_t mfgpt_tick(int irq, void *dev_id) { + /* Turn off the clock (and clear the event) */ + mfgpt_disable_timer(mfgpt_event_clock); + if (mfgpt_tick_mode == CLOCK_EVT_MODE_SHUTDOWN) return IRQ_HANDLED; - /* Turn off the clock */ - mfgpt_disable_timer(mfgpt_event_clock); - /* Clear the counter */ geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_COUNTER, 0); @@ -319,10 +334,6 @@ static int __init mfgpt_timer_setup(void) } mfgpt_event_clock = timer; - /* Set the clock scale and enable the event mode for CMP2 */ - val = MFGPT_SCALE | (3 << 8); - - geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_SETUP, val); /* Set up the IRQ on the MFGPT side */ if (geode_mfgpt_setup_irq(mfgpt_event_clock, MFGPT_CMP2, irq)) { @@ -339,6 +350,11 @@ static int __init mfgpt_timer_setup(void) goto err; } + /* Set the clock scale and enable the event mode for CMP2 */ + val = MFGPT_SCALE | (3 << 8); + + geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_SETUP, val); + /* Set up the clock event */ mfgpt_clockevent.mult = div_sc(MFGPT_HZ, NSEC_PER_SEC, 32); mfgpt_clockevent.min_delta_ns = clockevent_delta2ns(0xF, |