i2c: brcmstb: Add support for atomic transfers

Add support for atomic transfers using polling mode with interrupts
intentionally disabled to get rid of the warning introduced by commit
63b96983 ("i2c: core: introduce callbacks for atomic transfers")
during system reboot and power-off.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/busses/i2c-brcmstb.c

@@ -160,6 +160,7 @@ struct brcmstb_i2c_dev {
 	struct completion done;
 	u32 clk_freq_hz;
 	int data_regsz;
+	bool atomic;
 };
 
 /* register accessors for both be and le cpu arch */
@@ -240,7 +241,7 @@ static int brcmstb_i2c_wait_for_completion(struct brcmstb_i2c_dev *dev)
 	int ret = 0;
 	unsigned long timeout = msecs_to_jiffies(I2C_TIMEOUT);
 
-	if (dev->irq >= 0) {
+	if (dev->irq >= 0 && !dev->atomic) {
 		if (!wait_for_completion_timeout(&dev->done, timeout))
 			ret = -ETIMEDOUT;
 	} else {
@@ -287,7 +288,7 @@ static int brcmstb_send_i2c_cmd(struct brcmstb_i2c_dev *dev,
 		return rc;
 
 	/* only if we are in interrupt mode */
-	if (dev->irq >= 0)
+	if (dev->irq >= 0 && !dev->atomic)
 		reinit_completion(&dev->done);
 
 	/* enable BSC CTL interrupt line */
@@ -520,6 +521,23 @@ static int brcmstb_i2c_xfer(struct i2c_adapter *adapter,
 
 }
 
+static int brcmstb_i2c_xfer_atomic(struct i2c_adapter *adapter,
+				   struct i2c_msg msgs[], int num)
+{
+	struct brcmstb_i2c_dev *dev = i2c_get_adapdata(adapter);
+	int ret;
+
+	if (dev->irq >= 0)
+		disable_irq(dev->irq);
+	dev->atomic = true;
+	ret = brcmstb_i2c_xfer(adapter, msgs, num);
+	dev->atomic = false;
+	if (dev->irq >= 0)
+		enable_irq(dev->irq);
+
+	return ret;
+}
+
 static u32 brcmstb_i2c_functionality(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR
@@ -528,6 +546,7 @@ static u32 brcmstb_i2c_functionality(struct i2c_adapter *adap)
 
 static const struct i2c_algorithm brcmstb_i2c_algo = {
 	.master_xfer = brcmstb_i2c_xfer,
+	.master_xfer_atomic = brcmstb_i2c_xfer_atomic,
 	.functionality = brcmstb_i2c_functionality,
 };