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| author | Jan Luebbe <jlu@pengutronix.de> | 2015-07-08 17:35:27 +0300 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2015-07-31 14:32:31 +0300 |
| commit | 828e66c0edf97bcb79b59b1ddd803a50629b3937 (patch) | |
| tree | 1e44d06f112c47c003f649fc64d6d7fae75893d9 /drivers/i2c/busses/i2c-omap.c | |
| parent | 8b06260836ab47abbb5ea49d889660a0ed8adf90 (diff) | |
| download | linux-828e66c0edf97bcb79b59b1ddd803a50629b3937.tar.xz | |
i2c: omap: fix bus recovery setup
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>
Diffstat (limited to 'drivers/i2c/busses/i2c-omap.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-omap.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index d1c22e3fdd14..fc9bf7f30e35 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -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); } |