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.
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@ -41,6 +41,7 @@ struct iicbus_softc
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{
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device_t dev; /* Myself */
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device_t owner; /* iicbus owner device structure */
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device_t busydev; /* iicbus_release_bus calls unbusy on this */
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u_int owncount; /* iicbus ownership nesting count */
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u_char started; /* address of the 'started' slave
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* 0 if no start condition succeeded */
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@ -131,9 +131,15 @@ iicbus_request_bus(device_t bus, device_t dev, int how)
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/*
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* Mark the device busy while it owns the bus, to
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* prevent detaching the device, bus, or hardware
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* controller, until ownership is relinquished.
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* controller, until ownership is relinquished. If the
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* device is doing IO from its probe method before
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* attaching, it cannot be busied; mark the bus busy.
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*/
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device_busy(dev);
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if (device_get_state(dev) < DS_ATTACHING)
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sc->busydev = bus;
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else
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sc->busydev = dev;
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device_busy(sc->busydev);
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/*
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* Drop the lock around the call to the bus driver, it
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* should be allowed to sleep in the IIC_WAIT case.
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@ -150,7 +156,7 @@ iicbus_request_bus(device_t bus, device_t dev, int how)
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sc->owner = NULL;
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sc->owncount = 0;
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wakeup_one(sc);
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device_unbusy(dev);
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device_unbusy(sc->busydev);
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}
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}
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}
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@ -184,7 +190,7 @@ iicbus_release_bus(device_t bus, device_t dev)
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IICBUS_LOCK(sc);
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sc->owner = NULL;
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wakeup_one(sc);
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device_unbusy(dev);
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device_unbusy(sc->busydev);
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}
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IICBUS_UNLOCK(sc);
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return (0);
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