/* Wait for transfer to complete, optionally check RXAK. */
static int
wait_for_xfer(struct i2c_softc *sc, int checkack)
{
int retry, sr;
/*
* Sleep for about the time it takes to transfer a byte (with precision
* set to tolerate 5% oversleep). We calculate the approximate byte
* transfer time when we set the bus speed divisor. Slaves are allowed
* to do clock-stretching so the actual transfer time can be larger, but
* this gets the bulk of the waiting out of the way without tying up the
* processor the whole time.
*/
pause_sbt("imxi2c", sc->byte_time_sbt, sc->byte_time_sbt / 20, 0);
retry = 10000;
while (retry --) {
sr = i2c_read_reg(sc, I2C_STATUS_REG);
if (sr & I2CSR_MIF) {
if (sr & I2CSR_MAL)
return (IIC_EBUSERR);
else if (checkack && (sr & I2CSR_RXAK))
return (IIC_ENOACK);
else
return (IIC_NOERR);
}
DELAY(1);
}
return (IIC_ETIMEOUT);
}
int
vmbus_msghc_exec_noresult(struct vmbus_msghc *mh)
{
sbintime_t time = SBT_1MS;
int i;
/*
* Save the input parameter so that we could restore the input
* parameter if the Hypercall failed.
*
* XXX
* Is this really necessary?! i.e. Will the Hypercall ever
* overwrite the input parameter?
*/
memcpy(&mh->mh_inprm_save, mh->mh_inprm, HYPERCALL_POSTMSGIN_SIZE);
/*
* In order to cope with transient failures, e.g. insufficient
* resources on host side, we retry the post message Hypercall
* several times. 20 retries seem sufficient.
*/
#define HC_RETRY_MAX 20
for (i = 0; i < HC_RETRY_MAX; ++i) {
uint64_t status;
status = hypercall_post_message(mh->mh_inprm_dma.hv_paddr);
if (status == HYPERCALL_STATUS_SUCCESS)
return 0;
pause_sbt("hcpmsg", time, 0, C_HARDCLOCK);
if (time < SBT_1S * 2)
time *= 2;
/* Restore input parameter and try again */
memcpy(mh->mh_inprm, &mh->mh_inprm_save,
HYPERCALL_POSTMSGIN_SIZE);
}
#undef HC_RETRY_MAX
return EIO;
}
