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i2c: export bit-banging algo functions

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i915 has a hw i2c controller (gmbus) but for a bunch of stupid reasons
we need to be able to fall back to the bit-banging algo on gpio pins.

The current code sets up a 2nd i2c controller for the same i2c bus using
the bit-banging algo. This has a bunch of issues, the major one being
that userspace can directly access this fallback i2c adaptor behind
the drivers back.

But we need to frob a few registers before and after using fallback
gpio bit-banging, so this horribly fails.

The new plan is to only set up one i2c adaptor and transparently fall
back to bit-banging by directly calling the xfer function of the bit-
banging algo in the i2c core.

To make that possible, export the 2 i2c algo functions.

v2: As suggested by Jean Delvare, simply export the i2c_bit_algo
vtable instead of the individual functions.

Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Daniel Vetter 2012-02-28 00:39:39 +01:00
parent 1298330bd6
commit b0209b3995
2 changed files with 3 additions and 1 deletions
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3
drivers/i2c/algos/i2c-algo-bit.c
View File

@ -610,10 +610,11 @@ static u32 bit_func(struct i2c_adapter *adap)
/* -----exported algorithm data: ------------------------------------- */
static const struct i2c_algorithm i2c_bit_algo = {
const struct i2c_algorithm i2c_bit_algo = {
.master_xfer = bit_xfer,
.functionality = bit_func,
};
EXPORT_SYMBOL(i2c_bit_algo);
/*
* registering functions to load algorithms at runtime

1
include/linux/i2c-algo-bit.h
View File

@ -49,5 +49,6 @@ struct i2c_algo_bit_data {
int i2c_bit_add_bus(struct i2c_adapter *);
int i2c_bit_add_numbered_bus(struct i2c_adapter *);
extern const struct i2c_algorithm i2c_bit_algo;
#endif /* _LINUX_I2C_ALGO_BIT_H */