i2c: designware: slave should do WRITE_REQUESTED before WRITE_RECEIVED

Sometimes we would get the following flow when doing an i2cset:

0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x514 : INTR_STAT=0x4
I2C_SLAVE_WRITE_RECEIVED
0x1 STATUS SLAVE_ACTIVITY=0x0 : RAW_INTR_STAT=0x714 : INTR_STAT=0x204
I2C_SLAVE_WRITE_REQUESTED
I2C_SLAVE_WRITE_RECEIVED

Documentation/i2c/slave-interface.rst says that I2C_SLAVE_WRITE_REQUESTED,
which is mandatory, should be sent while the data did not arrive yet. It
means in a write-request I2C_SLAVE_WRITE_REQUESTED should be reported
before any I2C_SLAVE_WRITE_RECEIVED.

By the way, I2C_SLAVE_STOP didn't be reported in the above case because
DW_IC_INTR_STAT was not 0x200.

dev->status can be used to record the current state, especially Designware
I2C controller has no interrupts to identify a write-request. This patch
makes not only I2C_SLAVE_WRITE_REQUESTED been reported first when
IC_INTR_RX_FULL is rising and dev->status isn't STATUS_WRITE_IN_PROGRESS
but also I2C_SLAVE_STOP been reported when a STOP condition is received.

Signed-off-by: Michael Wu <michael.wu@vatics.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

diff --git a/drivers/i2c/busses/i2c-designware-slave.c b/drivers/i2c/busses/i2c-designware-slave.c
index 13de01a..0d15f4c 100644 (file)
--- a/drivers/i2c/busses/i2c-designware-slave.c
+++ b/drivers/i2c/busses/i2c-designware-slave.c
@@ -172,26 +172,25 @@ static int i2c_dw_irq_handler_slave(struct dw_i2c_dev *dev)
                "%#x STATUS SLAVE_ACTIVITY=%#x : RAW_INTR_STAT=%#x : INTR_STAT=%#x\n",
                enabled, slave_activity, raw_stat, stat);
 
-       if ((stat & DW_IC_INTR_RX_FULL) && (stat & DW_IC_INTR_STOP_DET))
-               i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_REQUESTED, &val);
+       if (stat & DW_IC_INTR_RX_FULL) {
+               if (dev->status != STATUS_WRITE_IN_PROGRESS) {
+                       dev->status = STATUS_WRITE_IN_PROGRESS;
+                       i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_REQUESTED,
+                                       &val);
+               }
+
+               regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
+               val = tmp;
+               if (!i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED,
+                                    &val))
+                       dev_vdbg(dev->dev, "Byte %X acked!", val);
+       }
 
        if (stat & DW_IC_INTR_RD_REQ) {
                if (slave_activity) {
-                       if (stat & DW_IC_INTR_RX_FULL) {
-                               regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
-                               val = tmp;
-
-                               if (!i2c_slave_event(dev->slave,
-                                                    I2C_SLAVE_WRITE_RECEIVED,
-                                                    &val)) {
-                                       dev_vdbg(dev->dev, "Byte %X acked!",
-                                                val);
-                               }
-                               regmap_read(dev->map, DW_IC_CLR_RD_REQ, &tmp);
-                       } else {
-                               regmap_read(dev->map, DW_IC_CLR_RD_REQ, &tmp);
-                               regmap_read(dev->map, DW_IC_CLR_RX_UNDER, &tmp);
-                       }
+                       regmap_read(dev->map, DW_IC_CLR_RD_REQ, &tmp);
+
+                       dev->status = STATUS_READ_IN_PROGRESS;
                        if (!i2c_slave_event(dev->slave,
                                             I2C_SLAVE_READ_REQUESTED,
                                             &val))
@@ -203,18 +202,10 @@ static int i2c_dw_irq_handler_slave(struct dw_i2c_dev *dev)
                if (!i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED,
                                     &val))
                        regmap_read(dev->map, DW_IC_CLR_RX_DONE, &tmp);
-
-               i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);
-               return 1;
        }
 
-       if (stat & DW_IC_INTR_RX_FULL) {
-               regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
-               val = tmp;
-               if (!i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED,
-                                    &val))
-                       dev_vdbg(dev->dev, "Byte %X acked!", val);
-       } else {
+       if (stat & DW_IC_INTR_STOP_DET) {
+               dev->status = STATUS_IDLE;
                i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);
        }