[PATCH 3/4] gpio: dwapb: Use optional-clocks interface for APB ref-clocks

[<Sergey.Semin@baikalelectronics.ru>]

From: Serge Semin <Sergey.Semin@baikalelectronics.ru>

The common clocks kernel framework provide a generic way to use
an optional reference clock sources. If it's utilized there is no
need in checking whether the clocks descriptor is actually a
negative error at the moment of the prepare/unprepare clocks method
calling. So if the corresponding clock source is provided, then
getting an error shall actually terminate the device probe procedure.
If it isn't specified then the driver shall proceed with further
initializations.

We'll use the optional clocks getting method to handle the APB interface
reference clocks, which can be provided for instance in the device
of-node with "bus" clock-name.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
---
 drivers/gpio/gpio-dwapb.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/gpio/gpio-dwapb.c b/drivers/gpio/gpio-dwapb.c
index 92e127e74813..bfa16172f973 100644
--- a/drivers/gpio/gpio-dwapb.c
+++ b/drivers/gpio/gpio-dwapb.c
@@ -690,13 +690,16 @@ static int dwapb_gpio_probe(struct platform_device *pdev)
 		return PTR_ERR(gpio->regs);
 
 	/* Optional bus clock */
-	gpio->clk = devm_clk_get(&pdev->dev, "bus");
-	if (!IS_ERR(gpio->clk)) {
-		err = clk_prepare_enable(gpio->clk);
-		if (err) {
-			dev_info(&pdev->dev, "Cannot enable clock\n");
-			return err;
-		}
+	gpio->clk = devm_clk_get_optional(&pdev->dev, "bus");
+	if (IS_ERR(gpio->clk)) {
+		dev_info(&pdev->dev, "Cannot get APB clock\n");
+		return PTR_ERR(gpio->clk);
+	}
+
+	err = clk_prepare_enable(gpio->clk);
+	if (err) {
+		dev_info(&pdev->dev, "Cannot enable APB clock\n");
+		return err;
 	}
 
 	gpio->flags = 0;
@@ -793,8 +796,7 @@ static int dwapb_gpio_resume(struct device *dev)
 	unsigned long flags;
 	int i;
 
-	if (!IS_ERR(gpio->clk))
-		clk_prepare_enable(gpio->clk);
+	clk_prepare_enable(gpio->clk);
 
 	spin_lock_irqsave(&gc->bgpio_lock, flags);
 	for (i = 0; i < gpio->nr_ports; i++) {
-- 
2.25.1