From b06750501f5c0eef7fef094f13d2f2e313c60b79 Mon Sep 17 00:00:00 2001
From: Simon Glass <sjg@chromium.org>
Date: Thu, 11 Feb 2016 13:23:25 -0700
Subject: [PATCH] dm: core: Add uclass_first_device_err() to return a valid
 device

A common pattern is to call uclass_first_device() and then check if it
actually returns a device. Add a new function which does this, returning
an error if there are no devices in that uclass.

Signed-off-by: Simon Glass <sjg@chromium.org>
---
 drivers/core/uclass.c | 13 +++++++++++++
 include/dm/uclass.h   | 15 +++++++++++++--
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/core/uclass.c b/drivers/core/uclass.c
index 12095e75a4..1141ce1ba3 100644
--- a/drivers/core/uclass.c
+++ b/drivers/core/uclass.c
@@ -401,6 +401,19 @@ int uclass_first_device(enum uclass_id id, struct udevice **devp)
 	return uclass_get_device_tail(dev, ret, devp);
 }
 
+int uclass_first_device_err(enum uclass_id id, struct udevice **devp)
+{
+	int ret;
+
+	ret = uclass_first_device(id, devp);
+	if (ret)
+		return ret;
+	else if (!*devp)
+		return -ENODEV;
+
+	return 0;
+}
+
 int uclass_next_device(struct udevice **devp)
 {
 	struct udevice *dev = *devp;
diff --git a/include/dm/uclass.h b/include/dm/uclass.h
index bfbd27afd6..fd368b6bd0 100644
--- a/include/dm/uclass.h
+++ b/include/dm/uclass.h
@@ -200,10 +200,21 @@ int uclass_get_device_by_phandle(enum uclass_id id, struct udevice *parent,
  *
  * @id: Uclass ID to look up
  * @devp: Returns pointer to the first device in that uclass, or NULL if none
- * @return 0 if OK (found or not found), -1 on error
+ * @return 0 if OK (found or not found), other -ve on error
  */
 int uclass_first_device(enum uclass_id id, struct udevice **devp);
 
+/**
+ * uclass_first_device_err() - Get the first device in a uclass
+ *
+ * The device returned is probed if necessary, and ready for use
+ *
+ * @id: Uclass ID to look up
+ * @devp: Returns pointer to the first device in that uclass, or NULL if none
+ * @return 0 if found, -ENODEV if not found, other -ve on error
+ */
+int uclass_first_device_err(enum uclass_id id, struct udevice **devp);
+
 /**
  * uclass_next_device() - Get the next device in a uclass
  *
@@ -211,7 +222,7 @@ int uclass_first_device(enum uclass_id id, struct udevice **devp);
  *
  * @devp: On entry, pointer to device to lookup. On exit, returns pointer
  * to the next device in the same uclass, or NULL if none
- * @return 0 if OK (found or not found), -1 on error
+ * @return 0 if OK (found or not found), other -ve on error
  */
 int uclass_next_device(struct udevice **devp);