Author: ian
Date: Wed Jan 24 03:09:41 2018
New Revision: 328311
URL: https://svnweb.freebsd.org/changeset/base/328311
Log:
Follow changes in r328307 by using new IIC_RECURSIVE flag.
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.
Modified:
head/sys/dev/iicbus/isl12xx.c
Modified: head/sys/dev/iicbus/isl12xx.c
==============================================================================
--- head/sys/dev/iicbus/isl12xx.c Wed Jan 24 00:52:25 2018
(r328310)
+++ head/sys/dev/iicbus/isl12xx.c Wed Jan 24 03:09:41 2018
(r328311)
@@ -137,18 +137,27 @@ static struct ofw_compat_data compat_data[] = {
};
#endif
+/*
+ * 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)
+
static inline int
isl12xx_read1(struct isl12xx_softc *sc, uint8_t reg, uint8_t *data)
{
- return (iicdev_readfrom(sc->dev, reg, data, 1, IIC_WAIT));
+ return (iicdev_readfrom(sc->dev, reg, data, 1, WAITFLAGS));
}
static inline int
isl12xx_write1(struct isl12xx_softc *sc, uint8_t reg, uint8_t val)
{
- return (iicdev_writeto(sc->dev, reg, &val, 1, IIC_WAIT));
+ return (iicdev_writeto(sc->dev, reg, &val, 1, WAITFLAGS));
}
static void
@@ -229,17 +238,23 @@ isl12xx_gettime(device_t dev, struct timespec *ts)
int err;
uint8_t hourmask, sreg;
- /* If power failed, we can't provide valid time. */
- if ((err = isl12xx_read1(sc, ISL12XX_SR_REG, &sreg)) != 0)
+ /*
+ * Read the status and time registers.
+ */
+ if ((err = iicbus_request_bus(sc->busdev, sc->dev, IIC_WAIT)) == 0) {
+ if ((err = isl12xx_read1(sc, ISL12XX_SR_REG, &sreg)) == 0) {
+ err = iicdev_readfrom(sc->dev, ISL12XX_SC_REG, &tregs,
+ sizeof(tregs), WAITFLAGS);
+ }
+ iicbus_release_bus(sc->busdev, sc->dev);
+ }
+ if (err != 0)
return (err);
+
+ /* If power failed, we can't provide valid time. */
if (sreg & ISL12XX_SR_RTCF)
return (EINVAL);
- /* Read the bcd time registers. */
- if ((err = iicdev_readfrom(sc->dev, ISL12XX_SC_REG, &tregs,
sizeof(tregs),
- IIC_WAIT)) != 0)
- return (EINVAL);
-
/* If chip is in AM/PM mode remember that for when we set time. */
if (tregs.hour & ISL12XX_24HR_FLAG) {
hourmask = ISL12xx_24HR_MASK;
@@ -319,7 +334,7 @@ isl12xx_settime(device_t dev, struct timespec *ts)
sreg |= ISL12XX_SR_WRTC | ISL12XX_SR_W0C_BITS;
if ((err = isl12xx_write1(sc, ISL12XX_SR_REG, sreg)) == 0) {
err = iicdev_writeto(sc->dev, ISL12XX_SC_REG, &tregs,
- sizeof(tregs), IIC_WAIT);
+ sizeof(tregs), WAITFLAGS);
sreg &= ~ISL12XX_SR_WRTC;
isl12xx_write1(sc, ISL12XX_SR_REG, sreg);
}
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