can: mcp251x: Use devm_clk_get_optional() to get the input clock

Simplify the code which fetches the input clock by using
devm_clk_get_optional(). This comes with a small functional change: previously
all errors were ignored when platform data is present. Now all errors are
treated as errors. If no input clock is present devm_clk_get_optional() will
return NULL instead of an error which matches the behavior of the old code.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/spi/mcp251x.c

@@ -994,15 +994,13 @@ static int mcp251x_can_probe(struct spi_device *spi)
 	struct clk *clk;
 	int freq, ret;
 
-	clk = devm_clk_get(&spi->dev, NULL);
-	if (IS_ERR(clk)) {
-		if (pdata)
-			freq = pdata->oscillator_frequency;
-		else
+	clk = devm_clk_get_optional(&spi->dev, NULL);
+	if (IS_ERR(clk))
 		return PTR_ERR(clk);
-	} else {
+
 	freq = clk_get_rate(clk);
-	}
+	if (freq == 0 && pdata)
+		freq = pdata->oscillator_frequency;
 
 	/* Sanity check */
 	if (freq < 1000000 || freq > 25000000)
@@ -1013,11 +1011,9 @@ static int mcp251x_can_probe(struct spi_device *spi)
 	if (!net)
 		return -ENOMEM;
 
-	if (!IS_ERR(clk)) {
 	ret = clk_prepare_enable(clk);
 	if (ret)
 		goto out_free;
-	}
 
 	net->netdev_ops = &mcp251x_netdev_ops;
 	net->flags |= IFF_ECHO;
@@ -1102,7 +1098,6 @@ static int mcp251x_can_probe(struct spi_device *spi)
 	mcp251x_power_enable(priv->power, 0);
 
 out_clk:
-	if (!IS_ERR(clk))
 	clk_disable_unprepare(clk);
 
 out_free:
@@ -1121,7 +1116,6 @@ static int mcp251x_can_remove(struct spi_device *spi)
 
 	mcp251x_power_enable(priv->power, 0);
 
-	if (!IS_ERR(priv->clk))
 	clk_disable_unprepare(priv->clk);
 
 	free_candev(net);