[Intel-gfx] [PATCH 3/7] i2c: export bit-banging algo functions

[Daniel Vetter]

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.

Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/i2c/algos/i2c-algo-bit.c |   12 +++++++-----
 include/linux/i2c-algo-bit.h     |    4 ++++
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
index 525c734..ec1651a 100644
--- a/drivers/i2c/algos/i2c-algo-bit.c
+++ b/drivers/i2c/algos/i2c-algo-bit.c
@@ -531,8 +531,8 @@ static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 	return 0;
 }
 
-static int bit_xfer(struct i2c_adapter *i2c_adap,
-		    struct i2c_msg msgs[], int num)
+int i2c_bit_xfer(struct i2c_adapter *i2c_adap,
+		 struct i2c_msg msgs[], int num)
 {
 	struct i2c_msg *pmsg;
 	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
@@ -598,21 +598,23 @@ bailout:
 		adap->post_xfer(i2c_adap);
 	return ret;
 }
+EXPORT_SYMBOL(i2c_bit_xfer);
 
-static u32 bit_func(struct i2c_adapter *adap)
+u32 i2c_bit_func(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |
 	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
 	       I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
 }
+EXPORT_SYMBOL(i2c_bit_func);
 
 
 /* -----exported algorithm data: -------------------------------------	*/
 
 static const struct i2c_algorithm i2c_bit_algo = {
-	.master_xfer	= bit_xfer,
-	.functionality	= bit_func,
+	.master_xfer	= i2c_bit_xfer,
+	.functionality	= i2c_bit_func,
 };
 
 /*
diff --git a/include/linux/i2c-algo-bit.h b/include/linux/i2c-algo-bit.h
index 4f98148..cdd6336 100644
--- a/include/linux/i2c-algo-bit.h
+++ b/include/linux/i2c-algo-bit.h
@@ -47,6 +47,10 @@ struct i2c_algo_bit_data {
 	int timeout;		/* in jiffies */
 };
 
+int i2c_bit_xfer(struct i2c_adapter *i2c_adap,
+		 struct i2c_msg msgs[], int num);
+u32 i2c_bit_func(struct i2c_adapter *adap);
+
 int i2c_bit_add_bus(struct i2c_adapter *);
 int i2c_bit_add_numbered_bus(struct i2c_adapter *);
 
-- 
1.7.7.5