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i2c: Support i2c_transfer in atomic contexts

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Allow i2c_transfer to be called in contexts where sleeping is not allowed.
It is the reponsability of the caller to ensure that the underlying i2c bus
driver will not sleep either.

Signed-off-by: Mike Rapoport <mike@compulab.co.il>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Mike Rapoport 2008-01-27 18:14:50 +01:00 committed by Jean Delvare
parent 5271071b20
commit cea443a81c
1 changed files with 11 additions and 1 deletions
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12
drivers/i2c/i2c-core.c
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@ -33,6 +33,8 @@
#include <linux/platform_device.h> #include <linux/platform_device.h>
#include <linux/mutex.h> #include <linux/mutex.h>
#include <linux/completion.h> #include <linux/completion.h>
#include <linux/hardirq.h>
#include <linux/irqflags.h>
#include <asm/uaccess.h> #include <asm/uaccess.h>
#include <asm/semaphore.h> #include <asm/semaphore.h>
@ -861,7 +863,15 @@ int i2c_transfer(struct i2c_adapter * adap, struct i2c_msg *msgs, int num)
} }
#endif #endif
mutex_lock_nested(&adap->bus_lock, adap->level); if (in_atomic() || irqs_disabled()) {
ret = mutex_trylock(&adap->bus_lock);
if (!ret)
/* I2C activity is ongoing. */
return -EAGAIN;
} else {
mutex_lock_nested(&adap->bus_lock, adap->level);
}
ret = adap->algo->master_xfer(adap,msgs,num); ret = adap->algo->master_xfer(adap,msgs,num);
mutex_unlock(&adap->bus_lock); mutex_unlock(&adap->bus_lock);