Author: ian
Date: Wed Jan 24 03:09:56 2018
New Revision: 328312
URL: https://svnweb.freebsd.org/changeset/base/328312
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/nxprtc.c
Modified: head/sys/dev/iicbus/nxprtc.c
==============================================================================
--- head/sys/dev/iicbus/nxprtc.c Wed Jan 24 03:09:41 2018
(r328311)
+++ head/sys/dev/iicbus/nxprtc.c Wed Jan 24 03:09:56 2018
(r328312)
@@ -198,6 +198,15 @@ 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_reg
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_re
{
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);
+ }
+ iicbus_release_bus(sc->busdev, sc->dev);
}
- if ((err = read_reg(sc, PCF85xx_R_CS1, &cs1)) != 0) {
- device_printf(dev, "cannot read RTC time\n");
+ 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. */
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