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-rw-r--r--drivers/i2c/mvtwsi.c42
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);