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twsi: protect interaction between twsi_transfer and twsi_intr

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All accesses to softc are now done under a mutex to prevent data races
between the open context and the interrupt handler.
Additionally, the wait time in twsi_transfer is bounded now.
Previously we could get stuck there forever if an interrupt got lost.

MFC after:	2 weeks
This commit is contained in:
Andriy Gapon 2021-11-26 09:25:01 +02:00
parent a2793d6182
commit 69cfa60ddd
1 changed files with 27 additions and 9 deletions
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36
sys/dev/iicbus/twsi/twsi.c
View File

@ -484,13 +484,16 @@ static int
twsi_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
{
struct twsi_softc *sc;
int error;
sc = device_get_softc(dev);
if (!sc->have_intr)
return (iicbus_transfer_gen(dev, msgs, nmsgs));
sc->error = 0;
mtx_lock(&sc->mutex);
KASSERT(sc->transfer == 0,
("starting a transfer while another is active"));
sc->control_val = TWSI_CONTROL_TWSIEN |
TWSI_CONTROL_INTEN | TWSI_CONTROL_ACK;
@ -501,6 +504,7 @@ twsi_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
sc->msgs = msgs;
sc->msg_idx = 0;
sc->transfer = 1;
sc->error = 0;
#ifdef TWSI_DEBUG
for (int i = 0; i < nmsgs; i++)
@ -512,22 +516,25 @@ twsi_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
if (sc->msgs[0].len == 1)
sc->control_val &= ~TWSI_CONTROL_ACK;
TWSI_WRITE(sc, sc->reg_control, sc->control_val | TWSI_CONTROL_START);
while (sc->error == 0 && sc->transfer != 0) {
tsleep_sbt(sc, 0, "twsi", SBT_1MS * 30, SBT_1MS, 0);
}
msleep_sbt(sc, &sc->mutex, 0, "twsi", 3000 * SBT_1MS, SBT_1MS, 0);
debugf(sc, "pause finish\n");
if (sc->error) {
debugf(sc, "Error, aborting (%d)\n", sc->error);
TWSI_WRITE(sc, sc->reg_control, 0);
if (sc->error == 0 && sc->transfer != 0) {
device_printf(sc->dev, "transfer timeout\n");
sc->error = IIC_ETIMEOUT;
sc->transfer = 0;
}
if (sc->error != 0)
debugf(sc, "Error: %d\n", sc->error);
/* Disable module and interrupts */
debugf(sc, "status=%x\n", TWSI_READ(sc, sc->reg_status));
TWSI_WRITE(sc, sc->reg_control, 0);
debugf(sc, "status=%x\n", TWSI_READ(sc, sc->reg_status));
error = sc->error;
mtx_unlock(&sc->mutex);
return (sc->error);
return (error);
}
static void
@ -539,11 +546,20 @@ twsi_intr(void *arg)
sc = arg;
mtx_lock(&sc->mutex);
debugf(sc, "Got interrupt Current msg=%x\n", sc->msg_idx);
status = TWSI_READ(sc, sc->reg_status);
debugf(sc, "reg control=%x\n", TWSI_READ(sc, sc->reg_control));
if (sc->transfer == 0) {
device_printf(sc->dev, "interrupt without active transfer, "
"status = 0x%x\n", status);
TWSI_WRITE(sc, sc->reg_control, sc->control_val |
TWSI_CONTROL_STOP);
goto end;
}
switch (status) {
case TWSI_STATUS_START:
case TWSI_STATUS_RPTD_START:
@ -670,6 +686,7 @@ twsi_intr(void *arg)
}
debugf(sc, "Refresh reg_control\n");
end:
/*
* Newer Allwinner chips clear IFLG after writing 1 to it.
*/
@ -681,6 +698,7 @@ twsi_intr(void *arg)
sc->transfer = 0;
wakeup(sc);
}
mtx_unlock(&sc->mutex);
}
static void