i2c: sh_mobile: send STOP according to datasheet

We initiate STOP (or REP_START) on the second last WAIT interrupt
currently. This works fine but is not according to the datasheet which
says to do it on the last WAIT interrupt. This also simplifies the code
quite a lot, so let's do it.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Tested-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-sh_mobile.c

@@ -40,21 +40,21 @@
 /* BUS:     S     A8     ACK   P(*)                                         */
 /* IRQ:       DTE   WAIT                                                    */
 /* ICIC:                                                                    */
-/* ICCR: 0x94 0x90                                                          */
+/* ICCR: 0x94       0x90                                                    */
 /* ICDR:      A8                                                            */
 /*                                                                          */
 /* 1 byte transmit                                                          */
 /* BUS:     S     A8     ACK   D8(1)   ACK   P(*)                           */
 /* IRQ:       DTE   WAIT         WAIT                                       */
 /* ICIC:      -DTE                                                          */
-/* ICCR: 0x94       0x90                                                    */
+/* ICCR: 0x94                    0x90                                       */
 /* ICDR:      A8    D8(1)                                                   */
 /*                                                                          */
 /* 2 byte transmit                                                          */
 /* BUS:     S     A8     ACK   D8(1)   ACK   D8(2)   ACK   P(*)             */
 /* IRQ:       DTE   WAIT         WAIT          WAIT                         */
 /* ICIC:      -DTE                                                          */
-/* ICCR: 0x94                    0x90                                       */
+/* ICCR: 0x94                                  0x90                         */
 /* ICDR:      A8    D8(1)        D8(2)                                      */
 /*                                                                          */
 /* 3 bytes or more, +---------+ gets repeated                               */
@@ -113,7 +113,6 @@ enum sh_mobile_i2c_op {
 	OP_TX_FIRST,
 	OP_TX,
 	OP_TX_STOP,
-	OP_TX_STOP_DATA,
 	OP_TX_TO_RX,
 	OP_RX,
 	OP_RX_STOP,
@@ -319,10 +318,7 @@ static unsigned char i2c_op(struct sh_mobile_i2c_data *pd,
 	case OP_TX: /* write data */
 		iic_wr(pd, ICDR, data);
 		break;
-	case OP_TX_STOP_DATA: /* write data and issue a stop afterwards */
-		iic_wr(pd, ICDR, data);
-		/* fallthrough */
-	case OP_TX_STOP: /* issue a stop */
+	case OP_TX_STOP: /* issue a stop (or rep_start) */
 		iic_wr(pd, ICCR, pd->send_stop ? ICCR_ICE | ICCR_TRS
 					       : ICCR_ICE | ICCR_TRS | ICCR_BBSY);
 		break;
@@ -356,11 +352,6 @@ static bool sh_mobile_i2c_is_first_byte(struct sh_mobile_i2c_data *pd)
 	return pd->pos == -1;
 }
 
-static bool sh_mobile_i2c_is_last_byte(struct sh_mobile_i2c_data *pd)
-{
-	return pd->pos == pd->msg->len - 1;
-}
-
 static void sh_mobile_i2c_get_data(struct sh_mobile_i2c_data *pd,
 				   unsigned char *buf)
 {
@@ -378,20 +369,12 @@ static int sh_mobile_i2c_isr_tx(struct sh_mobile_i2c_data *pd)
 	unsigned char data;
 
 	if (pd->pos == pd->msg->len) {
-		/* Send stop if we haven't yet (DMA case) */
-		if (pd->send_stop && pd->stop_after_dma)
-			i2c_op(pd, OP_TX_STOP, 0);
+		i2c_op(pd, OP_TX_STOP, 0);
 		return 1;
 	}
 
 	sh_mobile_i2c_get_data(pd, &data);
-
-	if (sh_mobile_i2c_is_last_byte(pd))
-		i2c_op(pd, OP_TX_STOP_DATA, data);
-	else if (sh_mobile_i2c_is_first_byte(pd))
-		i2c_op(pd, OP_TX_FIRST, data);
-	else
-		i2c_op(pd, OP_TX, data);
+	i2c_op(pd, sh_mobile_i2c_is_first_byte(pd) ? OP_TX_FIRST : OP_TX, data);
 
 	pd->pos++;
 	return 0;