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Follow changes in r328307 by using new IIC_RECURSIVE flag.

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The driver now ensures only one thread at a time is running in the API
functions (clock_gettime() and clock_settime()) by specifically requesting
ownership of the i2c bus without using IIC_RECURSIVE, then it does all IO
using IIC_RECURSIVE so that each individual IO operation doesn't try to
re-acquire the bus.

The other IO done by the driver happens at attach or intr_config_hooks time,
when there can't be multiple threads running with the same device instance.
So, the IIC_RECURSIVE flag can be safely ORed into the wait flags for all IO
done by the driver, because it's all either done in a single-threaded
environment, or protected within a block bounded by explict
iicbus_acquire_bus() and iicbus_release_bus() calls.
This commit is contained in:
Ian Lepore 2018-01-24 03:09:56 +00:00
parent 548778ed13
commit 8917c34a82
1 changed files with 20 additions and 10 deletions
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30
sys/dev/iicbus/nxprtc.c
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@ -197,6 +197,15 @@ struct nxprtc_softc {
#define SC_F_CPOL (1 << 0) /* Century bit means 19xx */
/*
* When doing i2c IO, indicate that we need to wait for exclusive bus ownership,
* but that we should not wait if we already own the bus. This lets us put
* iicbus_acquire_bus() calls with a non-recursive wait at the entry of our API
* functions to ensure that only one client at a time accesses the hardware for
* the entire series of operations it takes to read or write the clock.
*/
#define WAITFLAGS (IIC_WAIT | IIC_RECURSIVE)
/*
* We use the compat_data table to look up hint strings in the non-FDT case, so
* define the struct locally when we don't get it from ofw_bus_subr.h.
@ -230,14 +239,14 @@ static int
read_reg(struct nxprtc_softc *sc, uint8_t reg, uint8_t *val)
{
return (iicdev_readfrom(sc->dev, reg, val, sizeof(*val), IIC_WAIT));
return (iicdev_readfrom(sc->dev, reg, val, sizeof(*val), WAITFLAGS));
}
static int
write_reg(struct nxprtc_softc *sc, uint8_t reg, uint8_t val)
{
return (iicdev_writeto(sc->dev, reg, &val, sizeof(val), IIC_WAIT));
return (iicdev_writeto(sc->dev, reg, &val, sizeof(val), WAITFLAGS));
}
static int
@ -264,7 +273,7 @@ read_timeregs(struct nxprtc_softc *sc, struct time_regs *tregs, uint8_t *tmr)
continue;
}
if ((err = iicdev_readfrom(sc->dev, sc->secaddr, tregs,
sizeof(*tregs), IIC_WAIT)) != 0)
sizeof(*tregs), WAITFLAGS)) != 0)
break;
} while (sc->use_timer && tregs->sec != sec);
@ -294,7 +303,7 @@ write_timeregs(struct nxprtc_softc *sc, struct time_regs *tregs)
{
return (iicdev_writeto(sc->dev, sc->secaddr, tregs,
sizeof(*tregs), IIC_WAIT));
sizeof(*tregs), WAITFLAGS));
}
static int
@ -557,14 +566,15 @@ nxprtc_gettime(device_t dev, struct timespec *ts)
* bit is not set in the control reg. The latter can happen if there
* was an error when setting the time.
*/
if ((err = read_timeregs(sc, &tregs, &tmrcount)) != 0) {
device_printf(dev, "cannot read RTC time\n");
return (err);
if ((err = iicbus_request_bus(sc->busdev, sc->dev, IIC_WAIT)) == 0) {
if ((err = read_timeregs(sc, &tregs, &tmrcount)) == 0) {
err = read_reg(sc, PCF85xx_R_CS1, &cs1);
}
if ((err = read_reg(sc, PCF85xx_R_CS1, &cs1)) != 0) {
device_printf(dev, "cannot read RTC time\n");
return (err);
iicbus_release_bus(sc->busdev, sc->dev);
}
if (err != 0)
return (err);
if ((tregs.sec & PCF85xx_B_SECOND_OS) || (cs1 & PCF85xx_B_CS1_STOP)) {
device_printf(dev, "RTC clock not running\n");
return (EINVAL); /* hardware is good, time is not. */