[ARM] pxa: add MFP_PULL_FLOAT

There is currently an uncovered case for MFP configuration on PXAs which
is selected by setting the PULL_SEL bit but none of the PULL{UP,DOWN}_EN
bits. This case is needed to explicitly let pins float, even if the
selected alternate function would default to a configuration with a pull
resistor enabled.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>

arch/arm/plat-pxa/include/plat/mfp.h

@@ -325,8 +325,9 @@ typedef unsigned long mfp_cfg_t;
 #define MFP_PULL_LOW		(0x1 << 21)
 #define MFP_PULL_HIGH		(0x2 << 21)
 #define MFP_PULL_BOTH		(0x3 << 21)
-#define MFP_PULL_MASK		(0x3 << 21)
-#define MFP_PULL(x)		(((x) >> 21) & 0x3)
+#define MFP_PULL_FLOAT		(0x4 << 21)
+#define MFP_PULL_MASK		(0x7 << 21)
+#define MFP_PULL(x)		(((x) >> 21) & 0x7)
 
 #define MFP_CFG_DEFAULT		(MFP_AF0 | MFP_DS03X | MFP_LPM_DEFAULT |\
 				 MFP_LPM_EDGE_NONE | MFP_PULL_NONE)

arch/arm/plat-pxa/mfp.c

@@ -77,11 +77,13 @@
  * MFPR_PULL_LOW        1         0        1
  * MFPR_PULL_HIGH       1         1        0
  * MFPR_PULL_BOTH       1         1        1
+ * MFPR_PULL_FLOAT	1         0        0
  */
 #define MFPR_PULL_NONE		(0)
 #define MFPR_PULL_LOW		(MFPR_PULL_SEL | MFPR_PULLDOWN_EN)
 #define MFPR_PULL_BOTH		(MFPR_PULL_LOW | MFPR_PULLUP_EN)
 #define MFPR_PULL_HIGH		(MFPR_PULL_SEL | MFPR_PULLUP_EN)
+#define MFPR_PULL_FLOAT		(MFPR_PULL_SEL)
 
 /* mfp_spin_lock is used to ensure that MFP register configuration
  * (most likely a read-modify-write operation) is atomic, and that
@@ -116,6 +118,7 @@ static const unsigned long mfpr_pull[] = {
 	MFPR_PULL_LOW,
 	MFPR_PULL_HIGH,
 	MFPR_PULL_BOTH,
+	MFPR_PULL_FLOAT,
 };
 
 /* mapping of MFP_LPM_EDGE_* definitions to MFPR_EDGE_* register bits */