Commit 37b9ab92 authored by Laurent Vivier's avatar Laurent Vivier
Browse files

rtl8139: remove muldiv64() 



Originally, timers were ticks based, and it made sense to
add ticks to current time to know when to trigger an alarm.

But since commit:

74475455 change all other clock references to use nanosecond resolution accessors

All timers use nanoseconds and we need to convert ticks to nanoseconds, by
doing something like:

    y = muldiv64(x, get_ticks_per_sec(), PCI_FREQUENCY)

where x is the number of device ticks and y the number of system ticks.

y is used as nanoseconds in timer functions,
it works because 1 tick is 1 nanosecond.
(get_ticks_per_sec() is 10^9)

But as PCI frequency is 33 MHz, we can also do:

    y = x * 30; /* 33 MHz PCI period is 30 ns */

Which is much more simple.

This implies a 33.333333 MHz PCI frequency,
but this is correct.

Signed-off-by: default avatarLaurent Vivier <lvivier@redhat.com>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 9491e9bc

hw/net/rtl8139.c

+6 −8
Original line number Diff line number Diff line
@@ -64,7 +64,7 @@ 
/* debug RTL8139 card */

//#define DEBUG_RTL8139 1



#define PCI_FREQUENCY 33000000L

#define PCI_PERIOD 30    /* 30 ns period = 33.333333 Mhz frequency */



#define SET_MASKED(input, mask, curr) \

    ( ( (input) & ~(mask) ) | ( (curr) & (mask) ) )
@@ -2834,8 +2834,7 @@ static void rtl8139_io_writew(void *opaque, uint8_t addr, uint32_t val) 


static void rtl8139_set_next_tctr_time(RTL8139State *s)

{

    const uint64_t ns_per_period =

        muldiv64(0x100000000LL, get_ticks_per_sec(), PCI_FREQUENCY);

    const uint64_t ns_per_period = (uint64_t)PCI_PERIOD << 32;



    DPRINTF("entered rtl8139_set_next_tctr_time\n");
@@ -2853,7 +2852,7 @@ static void rtl8139_set_next_tctr_time(RTL8139State *s) 
    if (!s->TimerInt) {

        timer_del(s->timer);

    } else {

        uint64_t delta = muldiv64(s->TimerInt, get_ticks_per_sec(), PCI_FREQUENCY);

        uint64_t delta = (uint64_t)s->TimerInt * PCI_PERIOD;

        if (s->TCTR_base + delta <= qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL)) {

            delta += ns_per_period;

        }
@@ -3127,8 +3126,8 @@ static uint32_t rtl8139_io_readl(void *opaque, uint8_t addr) 
            break;



        case Timer:

            ret = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - s->TCTR_base,

                           PCI_FREQUENCY, get_ticks_per_sec());

            ret = (qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - s->TCTR_base) /

                  PCI_PERIOD;

            DPRINTF("TCTR Timer read val=0x%08x\n", ret);

            break;
@@ -3222,8 +3221,7 @@ static void rtl8139_pre_save(void *opaque) 
    int64_t current_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);



    /* for migration to older versions */

    s->TCTR = muldiv64(current_time - s->TCTR_base, PCI_FREQUENCY,

                       get_ticks_per_sec());

    s->TCTR = (current_time - s->TCTR_base) / PCI_PERIOD;

    s->rtl8139_mmio_io_addr_dummy = 0;

}

tests/rtl8139-test.c

+1 −1
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ static void nop(void) 
{

}



#define CLK 33000000

#define CLK 33333333



static QPCIBus *pcibus;

static QPCIDevice *dev;