[PATCH v4 1/2] dm: core: add function uclass_probe_all() to probe all devices

[Vabhav Sharma]

From: Vabhav Sharma <vabhav.sharma at nxp.com>

Support a common method to probe all devices associated with uclass.

This includes data structures and code for finding the first device and
looping for remaining devices associated with uclasses (groups of devices
with the same purpose, e.g. all SERIAL ports will be in the same uclass).

An example is SBSA compliant PL011 UART IP, where firmware does the serial
port initialization and prepare uart device to let the kernel use it for
sending and reveiving the characters.SERIAL uclass will use this function
to initialize PL011 UART ports.

The feature is enabled with CONFIG_DM.

Signed-off-by: Vabhav Sharma <vabhav.sharma at nxp.com>
Reviewed-by: Stefan Roese <sr at denx.de>
Reviewed-by: Simon Glass <sjg at chromium.org>
--
  v4:
  Incorporated review comments of Simon
  Removed if (dev)..  conditional check

  v3:
  Incorporated review comments of Stephan,Simon
  Related discussion https://patchwork.ozlabs.org/project/uboot/patch/1601400
385-11854-1-git-send-email-vabhav.sharma at oss.nxp.com/
---
 drivers/core/uclass.c | 16 ++++++++++++++++
 include/dm/uclass.h   | 12 ++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/drivers/core/uclass.c b/drivers/core/uclass.c
index c3f1b73..a1dc8bb 100644
--- a/drivers/core/uclass.c
+++ b/drivers/core/uclass.c
@@ -792,6 +792,22 @@ int uclass_pre_remove_device(struct udevice *dev)
 }
 #endif
 
+int uclass_probe_all(enum uclass_id id)
+{
+	struct udevice *dev;
+	int ret;
+
+	ret = uclass_first_device(id, &dev);
+	if (ret || !dev)
+		return ret;
+
+	/* Scanning uclass to probe all devices */
+	for (; dev; uclass_next_device(&dev))
+		;
+
+	return 0;
+}
+
 UCLASS_DRIVER(nop) = {
 	.id		= UCLASS_NOP,
 	.name		= "nop",
diff --git a/include/dm/uclass.h b/include/dm/uclass.h
index 7188304..7ac0aaa 100644
--- a/include/dm/uclass.h
+++ b/include/dm/uclass.h
@@ -381,6 +381,18 @@ int uclass_first_device_drvdata(enum uclass_id id, ulong driver_data,
 int uclass_resolve_seq(struct udevice *dev);
 
 /**
+ * uclass_probe_all() - Probe all devices based on an uclass ID
+ *
+ * Every uclass is identified by an ID, a number from 0 to n-1 where n is
+ * the number of uclasses. This function probe all devices asocciated with
+ * a uclass by looking its ID.
+ *
+ * @id: uclass ID to look up
+ * @return 0 if OK, other -ve on error
+ */
+int uclass_probe_all(enum uclass_id id);
+
+/**
  * uclass_id_foreach_dev() - Helper function to iteration through devices
  *
  * This creates a for() loop which works through the available devices in
-- 
2.7.4