Re: Dell BIOS and HPET timer support

From: Jon Smirl
Date: Wed Jun 08 2005 - 20:40:03 EST


On 6/8/05, Lee Revell <rlrevell@xxxxxxxxxxx> wrote:
> Check the source, it's self-explanatory. See hpet_alloc().

What is going on with do_div()?
0x0429b17f /100000 = 69.8 in my caculator. It comes back as 0 from do_div().

[jonsmirl@jonsmirl ~]$ dmesg | grep HPET
HPET: cap 0429b17f8086a201 period 0429b17f
HPET: period 0429b17f ns 0429b17f
HPET: period 0429b17f ns 00000000
Using HPET for base-timer
Using HPET for gettimeofday
[jonsmirl@jonsmirl ~]$


hpetp->hp_period = (cap & HPET_COUNTER_CLK_PERIOD_MASK) >>
HPET_COUNTER_CLK_PERIOD_SHIFT;
printk(KERN_ERR "HPET: cap %016llx period %08lx\n", cap, hpetp->hp_period);

ns = hpetp->hp_period; /* femptoseconds, 10^-15 */
printk(KERN_ERR "HPET: period %08lx ns %08lx \n", hpetp->hp_period, ns);
do_div(ns, 1000000); /* convert to nanoseconds, 10^-9 */
printk(KERN_ERR "HPET: period %08lx ns %08lx \n", hpetp->hp_period, ns);
printk(KERN_INFO "hpet%d: %ldns tick, %d %d-bit timers\n",
hpetp->hp_which, ns, hpetp->hp_ntimer,
cap & HPET_COUNTER_SIZE_MASK ? 64 : 32);
--
Jon Smirl
jonsmirl@xxxxxxxxx
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