dm: video: Add support for video bridges

A video bridge typically converts video from one format to another, e.g.
DisplayPort to LVDS. Add driver model support for these with a simple
interface to control activation and backlight. The uclass supports GPIO
control of power and reset lines.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/video/Kconfig

@@ -240,3 +240,5 @@ config VIDEO_TEGRA124
 	   HDMI. At present only eDP is supported by U-Boot. This option
 	   enables this support which can be used on devices which
 	   have an eDP display connected.
+
+source "drivers/video/bridge/Kconfig"

drivers/video/Makefile

@@ -54,3 +54,5 @@ obj-$(CONFIG_AM335X_LCD) += am335x-fb.o
 obj-$(CONFIG_VIDEO_PARADE) += parade.o
 
 obj-${CONFIG_VIDEO_TEGRA124} += tegra124/
+
+obj-y += bridge/

drivers/video/bridge/Kconfig

@@ -0,0 +1,8 @@
+config VIDEO_BRIDGE
+	bool "Support video bridges"
+	depends on DM
+	help
+	  Some platforms use video bridges to convert from one output to
+	  another. For example, where the SoC only supports eDP and the LCD
+	  requires LVDS, an eDP->LVDS bridge chip can be used to provide the
+	  necessary conversion. This option enables support for these devices.

drivers/video/bridge/Makefile

@@ -0,0 +1,7 @@
+#
+#  Copyright (C) 2015 Google, Inc
+#  Written by Simon Glass <sjg@chromium.org>
+#
+#  SPDX-License-Identifier:	GPL-2.0+
+
+obj-$(CONFIG_VIDEO_BRIDGE) += video-bridge-uclass.o

drivers/video/bridge/video-bridge-uclass.c

@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <video_bridge.h>
+
+int video_bridge_set_backlight(struct udevice *dev, int percent)
+{
+	struct video_bridge_ops *ops = video_bridge_get_ops(dev);
+
+	if (!ops->set_backlight)
+		return -ENOSYS;
+
+	return ops->set_backlight(dev, percent);
+}
+
+int video_bridge_attach(struct udevice *dev)
+{
+	struct video_bridge_ops *ops = video_bridge_get_ops(dev);
+
+	if (!ops->attach)
+		return -ENOSYS;
+
+	return ops->attach(dev);
+}
+
+int video_bridge_check_attached(struct udevice *dev)
+{
+	struct video_bridge_priv *uc_priv = dev_get_uclass_priv(dev);
+	struct video_bridge_ops *ops = video_bridge_get_ops(dev);
+	int ret;
+
+	if (!ops->check_attached) {
+		ret = dm_gpio_get_value(&uc_priv->hotplug);
+
+		return ret > 0 ? 0 : ret == 0 ? -ENOTCONN : ret;
+	}
+
+	return ops->check_attached(dev);
+}
+
+static int video_bridge_pre_probe(struct udevice *dev)
+{
+	struct video_bridge_priv *uc_priv = dev_get_uclass_priv(dev);
+	int ret;
+
+	debug("%s\n", __func__);
+	ret = gpio_request_by_name(dev, "sleep-gpios", 0,
+				   &uc_priv->sleep, GPIOD_IS_OUT);
+	if (ret) {
+		debug("%s: Could not decode sleep-gpios (%d)\n", __func__, ret);
+		return ret;
+	}
+	ret = dm_gpio_set_pull(&uc_priv->sleep, GPIO_PULL_NONE);
+	if (ret) {
+		debug("%s: Could not set sleep pull value\n", __func__);
+		return ret;
+	}
+	ret = gpio_request_by_name(dev, "reset-gpios", 0, &uc_priv->reset,
+				   GPIOD_IS_OUT);
+	if (ret) {
+		debug("%s: Could not decode reset-gpios (%d)\n", __func__, ret);
+		return ret;
+	}
+	ret = dm_gpio_set_pull(&uc_priv->reset, GPIO_PULL_NONE);
+	if (ret) {
+		debug("%s: Could not set reset pull value\n", __func__);
+		return ret;
+	}
+	ret = gpio_request_by_name(dev, "hotplug-gpios", 0, &uc_priv->hotplug,
+				   GPIOD_IS_IN);
+	if (ret && ret != -ENOENT) {
+		debug("%s: Could not decode hotplug (%d)\n", __func__, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+int video_bridge_set_active(struct udevice *dev, bool active)
+{
+	struct video_bridge_priv *uc_priv = dev_get_uclass_priv(dev);
+	int ret;
+
+	debug("%s: %d\n", __func__, active);
+	ret = dm_gpio_set_value(&uc_priv->sleep, !active);
+	if (ret)
+		return ret;
+	if (active) {
+		ret = dm_gpio_set_value(&uc_priv->reset, true);
+		if (ret)
+			return ret;
+		udelay(10);
+		ret = dm_gpio_set_value(&uc_priv->reset, false);
+	}
+
+	return ret;
+}
+
+UCLASS_DRIVER(video_bridge) = {
+	.id		= UCLASS_VIDEO_BRIDGE,
+	.name		= "video_bridge",
+	.per_device_auto_alloc_size	= sizeof(struct video_bridge_priv),
+	.pre_probe	= video_bridge_pre_probe,
+};

include/dm/uclass-id.h

@@ -57,6 +57,7 @@ enum uclass_id {
 	UCLASS_USB,		/* USB bus */
 	UCLASS_USB_DEV_GENERIC,	/* USB generic device */
 	UCLASS_USB_HUB,		/* USB hub */
+	UCLASS_VIDEO_BRIDGE,	/* Video bridge, e.g. DisplayPort to LVDS */
 
 	UCLASS_COUNT,
 	UCLASS_INVALID = -1,

include/video_bridge.h

@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __VIDEO_BRIDGE
+#define __VIDEO_BRIDGE
+
+#include <asm/gpio.h>
+
+/**
+ * struct video_bridge_priv - uclass information for video bridges
+ *
+ * @sleep:	GPIO to assert to power down the bridge
+ * @reset:	GPIO to assert to reset the bridge
+ * @hotplug:	Optional GPIO to check if bridge is connected
+ */
+struct video_bridge_priv {
+	struct gpio_desc sleep;
+	struct gpio_desc reset;
+	struct gpio_desc hotplug;
+};
+
+/**
+ * Operations for video bridges
+ */
+struct video_bridge_ops {
+	/**
+	 * attach() - attach a video bridge
+	 *
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*attach)(struct udevice *dev);
+
+	/**
+	 * check_attached() - check if a bridge is correctly attached
+	 *
+	 * This method is optional - if not provided then the hotplug GPIO
+	 * will be checked instead.
+	 *
+	 * @dev:	Device to check
+	 * @return 0 if attached, -EENOTCONN if not, or other -ve error
+	 */
+	int (*check_attached)(struct udevice *dev);
+
+	/**
+	 * set_backlight() - Set the backlight brightness
+	 *
+	 * @dev:	device to adjust
+	 * @percent:	brightness percentage (0=off, 100=full brightness)
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*set_backlight)(struct udevice *dev, int percent);
+};
+
+#define video_bridge_get_ops(dev) \
+		((struct video_bridge_ops *)(dev)->driver->ops)
+
+/**
+ * video_bridge_attach() - attach a video bridge
+ *
+ * @return 0 if OK, -ve on error
+ */
+int video_bridge_attach(struct udevice *dev);
+
+/**
+ * video_bridge_set_backlight() - Set the backlight brightness
+ *
+ * @percent:	brightness percentage (0=off, 100=full brightness)
+ * @return 0 if OK, -ve on error
+ */
+int video_bridge_set_backlight(struct udevice *dev, int percent);
+
+/**
+ * video_bridge_set_active() - take the bridge in/out of reset/powerdown
+ *
+ * @dev:	Device to adjust
+ * @active:	true to power up and reset, false to power down
+ */
+int video_bridge_set_active(struct udevice *dev, bool active);
+
+/**
+ * check_attached() - check if a bridge is correctly attached
+ *
+ * @dev:	Device to check
+ * @return 0 if attached, -EENOTCONN if not, or other -ve error
+ */
+int video_bridge_check_attached(struct udevice *dev);
+
+#endif