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The PPS code needs to be much more brutal to avoid synchronism on

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hardware with non-sucky clocks.
This commit is contained in:
Poul-Henning Kamp 2004-03-15 21:47:34 +00:00
parent 11d3e039e6
commit f6c21c0641
1 changed files with 32 additions and 14 deletions
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46
sys/i386/i386/elan-mmcr.c
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@ -68,16 +68,18 @@ __FBSDID("$FreeBSD$");
static char gpio_config[33];
static volatile uint16_t *mmcrptr;
volatile struct elan_mmcr * elan_mmcr;
volatile struct elan_mmcr *elan_mmcr;
#ifdef CPU_ELAN_PPS
static struct pps_state elan_pps;
u_int pps_a, pps_d;
u_int echo_a, echo_d;
static volatile uint16_t *pps_ap[3];
static u_int pps_a, pps_d;
static u_int echo_a, echo_d;
#endif /* CPU_ELAN_PPS */
#ifdef CPU_SOEKRIS
u_int led_cookie[32];
dev_t led_dev[32];
static u_int led_cookie[32];
static dev_t led_dev[32];
static void
gpio_led(void *cookie, int state)
@ -158,6 +160,9 @@ sysctl_machdep_elan_gpio_config(SYSCTL_HANDLER_ARGS)
case 'P':
pps_d = u;
pps_a = 0xc30 + v;
pps_ap[0] = &mmcrptr[pps_a / 2];
pps_ap[1] = &elan_mmcr->GPTMR2CNT;
pps_ap[2] = &elan_mmcr->GPTMR1CNT;
mmcrptr[(0xc2a + v) / 2] &= ~u;
gpio_config[i] = buf[i];
break;
@ -208,7 +213,20 @@ elan_poll_pps(struct timecounter *tc)
{
static int state;
int i;
u_int u;
uint16_t u, x, y, z;
u_long eflags;
/*
* Grab the HW state as quickly and compactly as we can. Disable
* interrupts to avoid measuring our interrupt service time on
* hw with quality clock sources.
*/
eflags = read_eflags();
disable_intr();
x = *pps_ap[0]; /* state, must be first, see below */
y = *pps_ap[1]; /* timer2 */
z = *pps_ap[2]; /* timer1 */
write_eflags(eflags);
/*
* Order is important here. We need to check the state of the GPIO
@ -217,13 +235,8 @@ elan_poll_pps(struct timecounter *tc)
* harmlessly read the REVID register and the contents of pps_d is
* of no concern.
*/
i = mmcrptr[pps_a / 2] & pps_d;
/*
* Subtract timer1 from timer2 to compensate for time from the
* edge until now.
*/
u = elan_mmcr->GPTMR2CNT - elan_mmcr->GPTMR1CNT;
i = x & pps_d;
/* If state did not change or we don't have a GPIO pin, return */
if (i == state || pps_a == 0)
@ -238,9 +251,14 @@ elan_poll_pps(struct timecounter *tc)
return;
}
/* State is "high", record the pps data */
/*
* Subtract timer1 from timer2 to compensate for time from the
* edge until we read the counters.
*/
u = y - z;
pps_capture(&elan_pps);
elan_pps.capcount = u & 0xffff;
elan_pps.capcount = u;
pps_event(&elan_pps, PPS_CAPTUREASSERT);
/* Twiddle echo bit */