Hi Manivannan,

On Thu, Jul 26, 2018 at 09:16:02PM +0530, Manivannan Sadhasivam wrote:

Add Actions Semiconductor Owl family S900 I2C driver.

Signed-off-by: Manivannan Sadhasivam <redacted>
Acked-by: Peter Rosin <redacted>

Looks mostly good already. Thanks Peter for the initial review!

+static irqreturn_t owl_i2c_interrupt(int irq, void *_dev)
+{
+	struct owl_i2c_dev *i2c_dev = _dev;
+	struct i2c_msg *msg = i2c_dev->msg;
+	unsigned long flags;
+	unsigned int stat, fifostat;
+
+	spin_lock_irqsave(&i2c_dev->lock, flags);
+
+	fifostat = readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT);
+	if (fifostat & OWL_I2C_FIFOSTAT_RNB) {
+		dev_dbg(&i2c_dev->adap.dev, "received NACK from device\n");
+		goto stop;
+	}
+
+	stat = readl(i2c_dev->base + OWL_I2C_REG_STAT);
+	if (stat & OWL_I2C_STAT_BEB) {
+		dev_dbg(&i2c_dev->adap.dev, "bus error\n");
+		goto stop;
+	}

I wonder if you can't pass back the different errors to the upper
layers? Like -ENXIO for NACK and -EIO for bus error? We have a
convention for that and it seems your HW can support it. The different
error codes would then maybe also make the debug outputs obsolete.

+	/*
+	 * Here, -ENXIO will be returned if interrupt occurred but no
+	 * read or write happened. Else if msg_ptr equals to message length,
+	 * message count will be returned.
+	 */
+	ret = i2c_dev->msg_ptr == msg->len ? num : -ENXIO;

I'd think this kinda unusual construct could go then as well by just
returning the error code derived from the interrupt handler above.

+static const struct i2c_adapter_quirks owl_i2c_quirks = {
+	.flags		= I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST,
+	.max_read_len   = 240,
+	.max_write_len  = 240,
+	.max_comb_1st_msg_len = 6,
+	.max_comb_2nd_msg_len = 240,
+};

Yay! Good use of the i2c_adapter_quirks struct :)

Regards,

   Wolfram

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