Input: olpc_apsp - enable the SP clock

Without the clock, the keyboard controller won't operate.
Tested on an OLPC XO 1.75.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/serio/olpc,ap-sp.txt

@@ -4,10 +4,14 @@ Required properties:
 - compatible : "olpc,ap-sp"
 - reg : base address and length of SoC's WTM registers
 - interrupts : SP-AP interrupt
+- clocks : phandle + clock-specifier for the clock that drives the WTM
+- clock-names:  should be "sp"
 
 Example:
 	ap-sp@d4290000 {
 		compatible = "olpc,ap-sp";
 		reg = <0xd4290000 0x1000>;
 		interrupts = <40>;
+		clocks = <&soc_clocks MMP2_CLK_SP>;
+		clock-names = "sp";
 	}

drivers/input/serio/olpc_apsp.c

@@ -23,6 +23,7 @@
 #include <linux/of.h>
 #include <linux/slab.h>
 #include <linux/delay.h>
+#include <linux/clk.h>
 
 /*
  * The OLPC XO-1.75 and XO-4 laptops do not have a hardware PS/2 controller.
@@ -74,6 +75,7 @@ struct olpc_apsp {
 	struct serio *kbio;
 	struct serio *padio;
 	void __iomem *base;
+	struct clk *clk;
 	int open_count;
 	int irq;
 };
@@ -146,11 +148,17 @@ static int olpc_apsp_open(struct serio *port)
 	struct olpc_apsp *priv = port->port_data;
 	unsigned int tmp;
 	unsigned long l;
+	int error;
 
 	if (priv->open_count++ == 0) {
+		error = clk_prepare_enable(priv->clk);
+		if (error)
+			return error;
+
 		l = readl(priv->base + COMMAND_FIFO_STATUS);
 		if (!(l & CMD_STS_MASK)) {
 			dev_err(priv->dev, "SP cannot accept commands.\n");
+			clk_disable_unprepare(priv->clk);
 			return -EIO;
 		}
 
@@ -171,6 +179,8 @@ static void olpc_apsp_close(struct serio *port)
 		/* Disable interrupt 0 */
 		tmp = readl(priv->base + PJ_INTERRUPT_MASK);
 		writel(tmp | INT_0, priv->base + PJ_INTERRUPT_MASK);
+
+		clk_disable_unprepare(priv->clk);
 	}
 }
 
@@ -198,6 +208,10 @@ static int olpc_apsp_probe(struct platform_device *pdev)
 	if (priv->irq < 0)
 		return priv->irq;
 
+	priv->clk = devm_clk_get(&pdev->dev, "sp");
+	if (IS_ERR(priv->clk))
+		return PTR_ERR(priv->clk);
+
 	/* KEYBOARD */
 	kb_serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
 	if (!kb_serio)