drivers/iio/adc/at91_adc.c: use clk_prepare_enable and clk_disable_unprepare

Clk_prepare_enable and clk_disable_unprepare combine clk_prepare and
clk_enable, and clk_disable and clk_unprepare.  They make the code more
concise, and ensure that clk_unprepare is called when clk_enable fails.

A simplified version of the semantic patch that introduces calls to these
functions is as follows: (http://coccinelle.lip6.fr/)

// <smpl>
@@
expression e;
@@

- clk_prepare(e);
- clk_enable(e);
+ clk_prepare_enable(e);

@@
expression e;
@@

- clk_disable(e);
- clk_unprepare(e);
+ clk_disable_unprepare(e);
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/adc/at91_adc.c

@@ -589,18 +589,13 @@ static int __devinit at91_adc_probe(struct platform_device *pdev)
 		goto error_free_irq;
 	}
 
-	ret = clk_prepare(st->clk);
+	ret = clk_prepare_enable(st->clk);
 	if (ret) {
-		dev_err(&pdev->dev, "Could not prepare the clock.\n");
+		dev_err(&pdev->dev,
+			"Could not prepare or enable the clock.\n");
 		goto error_free_irq;
 	}
 
-	ret = clk_enable(st->clk);
-	if (ret) {
-		dev_err(&pdev->dev, "Could not enable the clock.\n");
-		goto error_unprepare_clk;
-	}
-
 	st->adc_clk = devm_clk_get(&pdev->dev, "adc_op_clk");
 	if (IS_ERR(st->adc_clk)) {
 		dev_err(&pdev->dev, "Failed to get the ADC clock.\n");
@@ -608,18 +603,13 @@ static int __devinit at91_adc_probe(struct platform_device *pdev)
 		goto error_disable_clk;
 	}
 
-	ret = clk_prepare(st->adc_clk);
+	ret = clk_prepare_enable(st->adc_clk);
 	if (ret) {
-		dev_err(&pdev->dev, "Could not prepare the ADC clock.\n");
+		dev_err(&pdev->dev,
+			"Could not prepare or enable the ADC clock.\n");
 		goto error_disable_clk;
 	}
 
-	ret = clk_enable(st->adc_clk);
-	if (ret) {
-		dev_err(&pdev->dev, "Could not enable the ADC clock.\n");
-		goto error_unprepare_adc_clk;
-	}
-
 	/*
 	 * Prescaler rate computation using the formula from the Atmel's
 	 * datasheet : ADC Clock = MCK / ((Prescaler + 1) * 2), ADC Clock being
@@ -681,13 +671,9 @@ error_remove_triggers:
 error_unregister_buffer:
 	at91_adc_buffer_remove(idev);
 error_disable_adc_clk:
-	clk_disable(st->adc_clk);
-error_unprepare_adc_clk:
-	clk_unprepare(st->adc_clk);
+	clk_disable_unprepare(st->adc_clk);
 error_disable_clk:
-	clk_disable(st->clk);
-error_unprepare_clk:
-	clk_unprepare(st->clk);
+	clk_disable_unprepare(st->clk);
 error_free_irq:
 	free_irq(st->irq, idev);
 error_free_device:
@@ -705,8 +691,7 @@ static int __devexit at91_adc_remove(struct platform_device *pdev)
 	at91_adc_trigger_remove(idev);
 	at91_adc_buffer_remove(idev);
 	clk_disable_unprepare(st->adc_clk);
-	clk_disable(st->clk);
-	clk_unprepare(st->clk);
+	clk_disable_unprepare(st->clk);
 	free_irq(st->irq, idev);
 	iio_device_free(idev);