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i2c: omap: fix bus recovery setup

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At least on the AM335x, enabling OMAP_I2C_SYSTEST_ST_EN is not enough to
allow direct access to the SCL and SDA pins. In addition to ST_EN, we
need to set the TMODE to 0b11 (Loop back & SDA/SCL IO mode select).
Also, as the reset values of SCL_O and SDA_O are 0 (which means "drive
low level"), we need to set them to 1 (which means "high-impedance") to
avoid unwanted changes on the pins.

As a precaution, reset all these bits to their default values after
recovery is complete.

Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
Tested-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Jan Luebbe 2015-07-08 16:35:27 +02:00 committed by Wolfram Sang
parent 8b06260836
commit 828e66c0ed
1 changed files with 11 additions and 0 deletions
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11
drivers/i2c/busses/i2c-omap.c
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@ -1247,7 +1247,14 @@ static void omap_i2c_prepare_recovery(struct i2c_adapter *adap)
u32 reg;
reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
/* enable test mode */
reg |= OMAP_I2C_SYSTEST_ST_EN;
/* select SDA/SCL IO mode */
reg |= 3 << OMAP_I2C_SYSTEST_TMODE_SHIFT;
/* set SCL to high-impedance state (reset value is 0) */
reg |= OMAP_I2C_SYSTEST_SCL_O;
/* set SDA to high-impedance state (reset value is 0) */
reg |= OMAP_I2C_SYSTEST_SDA_O;
omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
}
@ -1257,7 +1264,11 @@ static void omap_i2c_unprepare_recovery(struct i2c_adapter *adap)
u32 reg;
reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
/* restore reset values */
reg &= ~OMAP_I2C_SYSTEST_ST_EN;
reg &= ~OMAP_I2C_SYSTEST_TMODE_MASK;
reg &= ~OMAP_I2C_SYSTEST_SCL_O;
reg &= ~OMAP_I2C_SYSTEST_SDA_O;
omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg);
}