From a29aaf55cd6faa75e35abfe00bd3ffc537490485 Mon Sep 17 00:00:00 2001 From: Moiz Sonasath Date: Tue, 16 Feb 2010 18:57:21 -0600 Subject: 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 Signed-off-by: Allen Pais Signed-off-by: Samuel Ortiz --- include/linux/i2c/twl.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include') 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 -- cgit v1.2.3