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authorJan Luebbe <jlu@pengutronix.de>2015-07-08 17:35:27 +0300
committerWolfram Sang <wsa@the-dreams.de>2015-07-31 14:32:31 +0300
commit828e66c0edf97bcb79b59b1ddd803a50629b3937 (patch)
tree1e44d06f112c47c003f649fc64d6d7fae75893d9 /drivers/i2c
parent8b06260836ab47abbb5ea49d889660a0ed8adf90 (diff)
downloadlinux-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')
-rw-r--r--drivers/i2c/busses/i2c-omap.c11
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);
}