[ARM] 5087/1: Get the PWM layer to handle clock enable/disable properly.

Allow pwm_enable()/pwm_disable() to be called as many times
as the driver wants (and not even count them).
The PWM model is different from things like the clock API
where we need enable counting, because PWMs have one
exclusive user per PWM whereas the clock API can have
multiple users of the same clock.
Acked-by: eric miao <eric.miao@marvell.com>
Signed-off-by: Robert Jarzmik <rjarzmik@free.fr>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-pxa/pwm.c

@@ -36,6 +36,7 @@ struct pwm_device {
 
 	const char	*label;
 	struct clk	*clk;
+	int		clk_enabled;
 	void __iomem	*mmio_base;
 
 	unsigned int	use_count;
@@ -87,13 +88,23 @@ EXPORT_SYMBOL(pwm_config);
 
 int pwm_enable(struct pwm_device *pwm)
 {
-	return clk_enable(pwm->clk);
+	int rc = 0;
+
+	if (!pwm->clk_enabled) {
+		rc = clk_enable(pwm->clk);
+		if (!rc)
+			pwm->clk_enabled = 1;
+	}
+	return rc;
 }
 EXPORT_SYMBOL(pwm_enable);
 
 void pwm_disable(struct pwm_device *pwm)
 {
-	clk_disable(pwm->clk);
+	if (pwm->clk_enabled) {
+		clk_disable(pwm->clk);
+		pwm->clk_enabled = 0;
+	}
 }
 EXPORT_SYMBOL(pwm_disable);
 
@@ -161,6 +172,7 @@ static struct pwm_device *pwm_probe(struct platform_device *pdev,
 		ret = PTR_ERR(pwm->clk);
 		goto err_free;
 	}
+	pwm->clk_enabled = 0;
 
 	pwm->use_count = 0;
 	pwm->pwm_id = pwm_id;