diff options
Diffstat (limited to 'chip/npcx/i2c.c')
| -rw-r--r-- | chip/npcx/i2c.c | 44 |
1 files changed, 28 insertions, 16 deletions
diff --git a/chip/npcx/i2c.c b/chip/npcx/i2c.c index 2a394c7cfb..a7af8632f0 100644 --- a/chip/npcx/i2c.c +++ b/chip/npcx/i2c.c @@ -73,6 +73,7 @@ enum smb_oper_state_t { SMB_MASTER_START, SMB_WRITE_OPER, SMB_READ_OPER, + SMB_DUMMY_READ_OPER, SMB_REPEAT_START, SMB_WRITE_SUSPEND, SMB_READ_SUSPEND, @@ -269,22 +270,24 @@ enum smb_error i2c_master_transaction(int controller) p_status->tx_buf[p_status->idx_buf-1]); } } else if (p_status->oper_state == SMB_READ_SUSPEND) { - /* Need to read the other bytes from next transaction */ - p_status->oper_state = SMB_READ_OPER; - if (p_status->sz_rxbuf == 1) { + /* + * Do dummy read if read length is 1 and I2C_XFER_STOP is set + * simultaneously. + */ + if (p_status->sz_rxbuf == 1 && + (p_status->flags & I2C_XFER_STOP)) { /* * Since SCL is released after reading last byte from - * previous transaction, we have no chance to set NACK - * bit if the next transaction is only one byte. Master - * cannot generate STOP when the last byte is ACK during - * receiving. + * previous transaction, adding a dummy byte for next + * transaction which let ec sets NACK bit in time is + * necessary. Or i2c master cannot generate STOP + * when the last byte is ACK during receiving. */ - CPRINTS("I2C %d rxbuf size should exceed one byte in " - "2th transaction", controller); - p_status->err_code = SMB_NO_SUPPORT_PTL; - i2c_recovery(controller, p_status); - return EC_ERROR_UNKNOWN; - } + p_status->sz_rxbuf++; + p_status->oper_state = SMB_DUMMY_READ_OPER; + } else + /* Need to read the other bytes from next transaction */ + p_status->oper_state = SMB_READ_OPER; } else cprints(CC_I2C, "Unexpected i2c state machine! %d", p_status->oper_state); @@ -444,7 +447,8 @@ static void i2c_handle_sda_irq(int controller) } } /* 3 Handle master read operation (read or after a write operation) */ - else if (p_status->oper_state == SMB_READ_OPER) { + else if (p_status->oper_state == SMB_READ_OPER || + p_status->oper_state == SMB_DUMMY_READ_OPER) { uint8_t data; /* last byte is about to be read - end of transaction */ if (p_status->idx_buf == (p_status->sz_rxbuf - 1)) { @@ -479,8 +483,12 @@ static void i2c_handle_sda_irq(int controller) I2C_READ_BYTE(controller, data); CPRINTS("-R(%02x)", data); - /* Read to buffer */ - p_status->rx_buf[p_status->idx_buf++] = data; + /* Read to buf. Skip last byte if meet SMB_DUMMY_READ_OPER */ + if (p_status->oper_state == SMB_DUMMY_READ_OPER && + p_status->idx_buf == (p_status->sz_rxbuf - 1)) + p_status->idx_buf++; + else + p_status->rx_buf[p_status->idx_buf++] = data; /* last byte is read - end of transaction */ if (p_status->idx_buf == p_status->sz_rxbuf) { @@ -628,6 +636,10 @@ int chip_i2c_xfer(int port, int slave_addr, const uint8_t *out, int out_size, if (ctrl < 0) return EC_ERROR_INVAL; + /* Skip unnecessary transaction */ + if (out_size == 0 && in_size == 0) + return EC_SUCCESS; + p_status = i2c_stsobjs + ctrl; /* Assign current task ID */ |