Author: ian
Date: Mon Jul 8 20:26:56 2019
New Revision: 349850
URL: https://svnweb.freebsd.org/changeset/base/349850
Log:
Restore the ability for i2c slave devices to do IO from their probe method.
r348164 added code to iicbus_request_bus/iicbus_release_bus to automatically
call device_busy()/device_unbusy() as part of aquiring exclusive use of the
bus (so modules can't be unloaded while the bus is exclusively owned and/or
IO is in progress). That broke the ability to do i2c IO from a slave device
probe method, because the slave isn't attached yet, so calling device_busy()
triggers a sanity-check panic for trying to busy a non-attached device.
Now we check whether the device status is < DS_ATTACHING, and if so we busy
the iicbus rather than the slave device. I think this leaves a small window
where a module could be unloaded while probing is in progress. But I think
that's true of all devices, and probably should be fixed by introducing a
DS_PROBING state for devices, and handling that at various points in the
newbus code.
Modified:
head/sys/dev/iicbus/iicbus.h
head/sys/dev/iicbus/iiconf.c
Modified: head/sys/dev/iicbus/iicbus.h
==============================================================================
--- head/sys/dev/iicbus/iicbus.h Mon Jul 8 20:20:01 2019
(r349849)
+++ head/sys/dev/iicbus/iicbus.h Mon Jul 8 20:26:56 2019
(r349850)
@@ -41,6 +41,7 @@ struct iicbus_softc
{
device_t dev; /* Myself */
device_t owner; /* iicbus owner device structure */
+ device_t busydev; /* iicbus_release_bus calls unbusy on this */
u_int owncount; /* iicbus ownership nesting count */
u_char started; /* address of the 'started' slave
* 0 if no start condition succeeded */
Modified: head/sys/dev/iicbus/iiconf.c
==============================================================================
--- head/sys/dev/iicbus/iiconf.c Mon Jul 8 20:20:01 2019
(r349849)
+++ head/sys/dev/iicbus/iiconf.c Mon Jul 8 20:26:56 2019
(r349850)
@@ -131,9 +131,15 @@ iicbus_request_bus(device_t bus, device_t dev, int how
/*
* Mark the device busy while it owns the bus, to
* prevent detaching the device, bus, or hardware
- * controller, until ownership is relinquished.
+ * controller, until ownership is relinquished. If the
+ * device is doing IO from its probe method before
+ * attaching, it cannot be busied; mark the bus busy.
*/
- device_busy(dev);
+ if (device_get_state(dev) < DS_ATTACHING)
+ sc->busydev = bus;
+ else
+ sc->busydev = dev;
+ device_busy(sc->busydev);
/*
* Drop the lock around the call to the bus driver, it
* should be allowed to sleep in the IIC_WAIT case.
@@ -150,7 +156,7 @@ iicbus_request_bus(device_t bus, device_t dev, int how
sc->owner = NULL;
sc->owncount = 0;
wakeup_one(sc);
- device_unbusy(dev);
+ device_unbusy(sc->busydev);
}
}
}
@@ -184,7 +190,7 @@ iicbus_release_bus(device_t bus, device_t dev)
IICBUS_LOCK(sc);
sc->owner = NULL;
wakeup_one(sc);
- device_unbusy(dev);
+ device_unbusy(sc->busydev);
}
IICBUS_UNLOCK(sc);
return (0);
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