diff options
Diffstat (limited to 'drivers/i2c/mvtwsi.c')
| -rw-r--r-- | drivers/i2c/mvtwsi.c | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/drivers/i2c/mvtwsi.c b/drivers/i2c/mvtwsi.c index 93bbc6916e..14cdb0f663 100644 --- a/drivers/i2c/mvtwsi.c +++ b/drivers/i2c/mvtwsi.c @@ -142,6 +142,8 @@ enum mvtwsi_ctrl_register_fields { * code. */ enum mvstwsi_status_values { + /* Protocol violation on bus; this is a terminal state */ + MVTWSI_BUS_ERROR = 0x00, /* START condition transmitted */ MVTWSI_STATUS_START = 0x08, /* Repeated START condition transmitted */ @@ -526,6 +528,36 @@ static void __twsi_i2c_init(struct mvtwsi_registers *twsi, int speed, } /* + * __twsi_i2c_reinit() - Reset and reinitialize the I2C controller. + * + * This function should be called to get the MVTWSI controller out of the + * "bus error" state. It saves and restores the baud and address registers. + * + * @twsi: The MVTWSI register structure to use. + * @tick: The duration of a clock cycle at the current I2C speed. + */ +static void __twsi_i2c_reinit(struct mvtwsi_registers *twsi, uint tick) +{ + uint baud; + uint slaveadd; + + /* Save baud, address registers */ + baud = readl(&twsi->baudrate); + slaveadd = readl(&twsi->slave_address); + + /* Reset controller */ + twsi_reset(twsi); + + /* Restore baud, address registers */ + writel(baud, &twsi->baudrate); + writel(slaveadd, &twsi->slave_address); + writel(0, &twsi->xtnd_slave_addr); + + /* Assert STOP, but don't care for the result */ + (void) twsi_stop(twsi, tick); +} + +/* * i2c_begin() - Start a I2C transaction. * * Begin a I2C transaction with a given expected start status and chip address. @@ -621,6 +653,11 @@ static int __twsi_i2c_read(struct mvtwsi_registers *twsi, uchar chip, int stop_status; int expected_start = MVTWSI_STATUS_START; + /* Check for (and clear) a bus error from a previous failed transaction + * or another master on the same bus */ + if (readl(&twsi->status) == MVTWSI_BUS_ERROR) + __twsi_i2c_reinit(twsi, tick); + if (alen > 0) { /* Begin i2c write to send the address bytes */ status = i2c_begin(twsi, expected_start, (chip << 1), tick); @@ -668,6 +705,11 @@ static int __twsi_i2c_write(struct mvtwsi_registers *twsi, uchar chip, { int status, stop_status; + /* Check for (and clear) a bus error from a previous failed transaction + * or another master on the same bus */ + if (readl(&twsi->status) == MVTWSI_BUS_ERROR) + __twsi_i2c_reinit(twsi, tick); + /* Begin i2c write to send first the address bytes, then the * data bytes */ status = i2c_begin(twsi, MVTWSI_STATUS_START, (chip << 1), tick); |