From: Dmitry Bazhenov dmitry.bazhenov@auriga.com
Due to a bug in the ThunderX I2C hardware sending STOP during a recovery attempt could lock up the hardware. To work around this problem do not send STOP at the beginning of the recovery but use the override registers to bring the TWSI including the high-level controller out of the bad state.
Signed-off-by: Dmitry Bazhenov dmitry.bazhenov@auriga.com Signed-off-by: Jan Glauber jglauber@cavium.com [Changed commit message] Signed-off-by: Wolfram Sang wsa@the-dreams.de
(cherry picked from commit de919ff6a0060510b099405d9b8f9413aba9ae14) Signed-off-by: Vadim Lomovtsev Vadim.Lomovtsev@caviumnetworks.com --- drivers/i2c/busses/i2c-octeon-core.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/drivers/i2c/busses/i2c-octeon-core.c b/drivers/i2c/busses/i2c-octeon-core.c index f322242..7d4df83 100644 --- a/drivers/i2c/busses/i2c-octeon-core.c +++ b/drivers/i2c/busses/i2c-octeon-core.c @@ -783,13 +783,14 @@ static void octeon_i2c_prepare_recovery(struct i2c_adapter *adap) { struct octeon_i2c *i2c = i2c_get_adapdata(adap);
+ octeon_i2c_hlc_disable(i2c); + /* - * The stop resets the state machine, does not _transmit_ STOP unless - * engine was active. + * Bring control register to a good state regardless + * of HLC state. */ - octeon_i2c_stop(i2c); + octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
- octeon_i2c_hlc_disable(i2c); octeon_i2c_write_int(i2c, 0); }
@@ -797,6 +798,15 @@ static void octeon_i2c_unprepare_recovery(struct i2c_adapter *adap) { struct octeon_i2c *i2c = i2c_get_adapdata(adap);
+ /* + * Generate STOP to finish the unfinished transaction. + * Can't generate STOP via the TWSI CTL register + * since it could bring the TWSI controller into an inoperable state. + */ + octeon_i2c_write_int(i2c, TWSI_INT_SDA_OVR | TWSI_INT_SCL_OVR); + udelay(5); + octeon_i2c_write_int(i2c, TWSI_INT_SDA_OVR); + udelay(5); octeon_i2c_write_int(i2c, 0); }