dm: pwm: Add a PWM uclass

Add a uclass that supports Pulse Width Modulation (PWM) devices. It
provides methods to enable/disable and configure the device.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/pwm/pwm-uclass.c b/drivers/pwm/pwm-uclass.c
new file mode 100644
index 0000000..c2200af
--- /dev/null
+++ b/drivers/pwm/pwm-uclass.c
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2016 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <pwm.h>
+
+int pwm_set_config(struct udevice *dev, uint channel, uint period_ns,
+		   uint duty_ns)
+{
+	struct pwm_ops *ops = pwm_get_ops(dev);
+
+	if (!ops->set_config)
+		return -ENOSYS;
+
+	return ops->set_config(dev, channel, period_ns, duty_ns);
+}
+
+int pwm_set_enable(struct udevice *dev, uint channel, bool enable)
+{
+	struct pwm_ops *ops = pwm_get_ops(dev);
+
+	if (!ops->set_enable)
+		return -ENOSYS;
+
+	return ops->set_enable(dev, channel, enable);
+}
+
+UCLASS_DRIVER(pwm) = {
+	.id		= UCLASS_PWM,
+	.name		= "pwm",
+};