mfd: Disable TWL4030/5030 I2C1/I2C4 internal pull-ups

This patch disables TWL4030/5030 I2C1 adn I2C4(SR) internal pull-up, to
use only the external HW resistor >=470 Ohm for the assured
functionality in HS mode.

While testing the I2C in High Speed mode, it was discovered that
without a proper pull-up resistor, there is data corruption during
multi-byte transfer. RTC(time_set) test case was used for testing.

From the analysis done, it was concluded that ideally we need a
pull-up of 1.6k Ohm(recomended) or atleast 470 Ohm or greater for
assured performance in HS mode.

Signed-off-by: Moiz Sonasath <m-sonasath@ti.com>
Signed-off-by: Allen Pais <allen.pais@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/i2c/twl.h b/include/linux/i2c/twl.h
index 9733e9e53f2b..e28d4c0e45bd 100644
--- a/include/linux/i2c/twl.h
+++ b/include/linux/i2c/twl.h
@@ -239,6 +239,21 @@ int twl6030_interrupt_mask(u8 bit_mask, u8 offset);
 
 /*----------------------------------------------------------------------*/
 
+/*Interface Bit Register (INTBR) offsets
+ *(Use TWL_4030_MODULE_INTBR)
+ */
+
+#define REG_GPPUPDCTR1                  0x0F
+
+/*I2C1 and I2C4(SR) SDA/SCL pull-up control bits */
+
+#define I2C_SCL_CTRL_PU                 BIT(0)
+#define I2C_SDA_CTRL_PU                 BIT(2)
+#define SR_I2C_SCL_CTRL_PU              BIT(4)
+#define SR_I2C_SDA_CTRL_PU              BIT(6)
+
+/*----------------------------------------------------------------------*/
+
 /*
  * Keypad register offsets (use TWL4030_MODULE_KEYPAD)
  * ... SIH/interrupt only