i2c: sh_mobile: use core to detect 'no zero length read' quirk

And don't reimplement in the driver.

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

drivers/i2c/busses/i2c-sh_mobile.c

@@ -613,11 +613,6 @@ static void sh_mobile_i2c_xfer_dma(struct sh_mobile_i2c_data *pd)
 static int start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg,
 		    bool do_init)
 {
-	if (usr_msg->len == 0 && (usr_msg->flags & I2C_M_RD)) {
-		dev_err(pd->dev, "Unsupported zero length i2c read\n");
-		return -EOPNOTSUPP;
-	}
-
 	if (do_init) {
 		/* Initialize channel registers */
 		iic_wr(pd, ICCR, ICCR_SCP);
@@ -758,6 +753,10 @@ static const struct i2c_algorithm sh_mobile_i2c_algorithm = {
 	.master_xfer	= sh_mobile_i2c_xfer,
 };
 
+static const struct i2c_adapter_quirks sh_mobile_i2c_quirks = {
+	.flags = I2C_AQ_NO_ZERO_LEN_READ,
+};
+
 /*
  * r8a7740 chip has lasting errata on I2C I/O pad reset.
  * this is work-around for it.
@@ -925,6 +924,7 @@ static int sh_mobile_i2c_probe(struct platform_device *dev)
 
 	adap->owner = THIS_MODULE;
 	adap->algo = &sh_mobile_i2c_algorithm;
+	adap->quirks = &sh_mobile_i2c_quirks;
 	adap->dev.parent = &dev->dev;
 	adap->retries = 5;
 	adap->nr = dev->id;