[U-Boot] [PATCH v2 2/6] dm: core: Allow multiple drivers to bind for a single node

[Philipp Tomsich]

Currently, driver binding stops once it encounters the first
compatible driver that doesn't refuse to bind. However, there are
cases where a single node will need to be handled by multiple driver
classes. For those cases we provide a configurable option to continue
to bind after the first driver has been found.

The first use cases for this are from the DM conversion of the sunxi
(Allwinner) architecture:
 * pinctrl (UCLASS_PINCTRL) and gpio (UCLASS_GPIO) drivers need to
   bind against a single node
 * clock (UCLASS_CLK) and reset (UCLASS_RESET) drivers also need to
   bind against a single node

Signed-off-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>
---
 drivers/core/Kconfig | 14 ++++++++++++++
 drivers/core/lists.c | 12 +++++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/core/Kconfig b/drivers/core/Kconfig
index 8749561..913101c 100644
--- a/drivers/core/Kconfig
+++ b/drivers/core/Kconfig
@@ -31,6 +31,20 @@ config DM_WARN
 	  This will cause dm_warn() to be compiled out - it will do nothing
 	  when called.
 
+config DM_ALLOW_MULTIPLE_DRIVERS
+        bool "Allow multiple drivers to bind for one node"
+	depends on DM
+	default n
+	help
+	  The driver model in U-Boot originally did not allow multiple
+	  drivers to bind for a single device node.
+
+	  If enabled, multiple drivers can now bind for a single node
+	  by using the same compatible string for matching: lists_bind_fdt()
+	  will assume that binding multiple drivers is desirable, if the
+	  caller does not request the pointer to the udevice structure to
+	  be returned (i.e. if devp is NULL).
+
 config DM_DEVICE_REMOVE
 	bool "Support device removal"
 	depends on DM
diff --git a/drivers/core/lists.c b/drivers/core/lists.c
index 23b6ba7..52efe69 100644
--- a/drivers/core/lists.c
+++ b/drivers/core/lists.c
@@ -166,7 +166,11 @@ int lists_bind_fdt(struct udevice *parent, const void *blob, int offset,
 		dm_dbg("   - attempt to match compatible string '%s'\n",
 		       compat);
 
-		for (entry = driver; entry != driver + n_ents; entry++) {
+		entry = driver;
+#if defined(CONFIG_DM_ALLOW_MULTIPLE_DRIVERS)
+	allow_more_matches:
+#endif
+		for (; entry != driver + n_ents; entry++) {
 			ret = driver_check_compatible(entry->of_match, &id,
 						      compat);
 			if (!ret)
@@ -190,6 +194,12 @@ int lists_bind_fdt(struct udevice *parent, const void *blob, int offset,
 			found = true;
 			if (devp)
 				*devp = dev;
+#if defined(CONFIG_DM_ALLOW_MULTIPLE_DRIVERS)
+			else {
+				entry++;
+				goto allow_more_matches;
+			}
+#endif
 		}
 		break;
 	}
-- 
1.9.1