tty/bcm63xx_uart: allow naming clock in device tree

Codify using a named clock for the refclk of the uart. This makes it
easier if we might need to add a gating clock (like present on the
BCM6345).
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: linux-mips@linux-mips.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-serial@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: bcm-kernel-feedback-list@broadcom.com
Patchwork: https://patchwork.linux-mips.org/patch/17328/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: James Hogan <jhogan@kernel.org>

Documentation/devicetree/bindings/serial/brcm,bcm6345-uart.txt

@@ -11,6 +11,11 @@ Required properties:
 - clocks: Clock driving the hardware; used to figure out the baud rate
   divisor.
 
+
+Optional properties:
+
+- clock-names: Should be "refclk".
+
 Example:
 
 	uart0: serial@14e00520 {
@@ -19,6 +24,7 @@ Example:
 		interrupt-parent = <&periph_intc>;
 		interrupts = <2>;
 		clocks = <&periph_clk>;
+		clock-names = "refclk";
 	};
 
 	clocks {

drivers/tty/serial/bcm63xx_uart.c

@@ -846,8 +846,10 @@ static int bcm_uart_probe(struct platform_device *pdev)
 	if (!res_irq)
 		return -ENODEV;
 
-	clk = pdev->dev.of_node ? of_clk_get(pdev->dev.of_node, 0) :
-				  clk_get(&pdev->dev, "refclk");
+	clk = clk_get(&pdev->dev, "refclk");
+	if (IS_ERR(clk) && pdev->dev.of_node)
+		clk = of_clk_get(pdev->dev.of_node, 0);
+
 	if (IS_ERR(clk))
 		return -ENODEV;