[PATCH v4 05/42] dm: core: Allow dropping run-time binding of devices

[Simon Glass <sjg@chromium.org>]

With OF_PLATDATA_INST devices are bound at build time. We should not need
binding of devices at runtime in most cases. However it is inflexible to
absolutely prohibit it, so add an option to control this.

Update the driver model core so that it does not bind devices. Update
device_bind() to return an error if called.

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

(no changes since v3)

Changes in v3:
- Update the commit message to explain OF_PLATDATA_NO_BIND better
- Update OF_PLATDATA_NO_BIND help as well

 drivers/core/device.c | 42 +++++++++++++++++++++++++-----------------
 dts/Kconfig           | 18 ++++++++++++++++++
 2 files changed, 43 insertions(+), 17 deletions(-)

diff --git a/drivers/core/device.c b/drivers/core/device.c
index 81f6880eac4..e915b3089de 100644
--- a/drivers/core/device.c
+++ b/drivers/core/device.c
@@ -45,6 +45,9 @@ static int device_bind_common(struct udevice *parent, const struct driver *drv,
 	bool auto_seq = true;
 	void *ptr;
 
+	if (CONFIG_IS_ENABLED(OF_PLATDATA_NO_BIND))
+		return -ENOSYS;
+
 	if (devp)
 		*devp = NULL;
 	if (!name)
@@ -395,26 +398,31 @@ int device_of_to_plat(struct udevice *dev)
 	if (dev_get_flags(dev) & DM_FLAG_PLATDATA_VALID)
 		return 0;
 
-	/* Ensure all parents have ofdata */
-	if (dev->parent) {
-		ret = device_of_to_plat(dev->parent);
+	/*
+	 * This is not needed if binding is disabled, since data is allocated
+	 * at build time.
+	 */
+	if (!CONFIG_IS_ENABLED(OF_PLATDATA_NO_BIND)) {
+		/* Ensure all parents have ofdata */
+		if (dev->parent) {
+			ret = device_of_to_plat(dev->parent);
+			if (ret)
+				goto fail;
+
+			/*
+			 * The device might have already been probed during
+			 * the call to device_probe() on its parent device
+			 * (e.g. PCI bridge devices). Test the flags again
+			 * so that we don't mess up the device.
+			 */
+			if (dev_get_flags(dev) & DM_FLAG_PLATDATA_VALID)
+				return 0;
+		}
+
+		ret = device_alloc_priv(dev);
 		if (ret)
 			goto fail;
-
-		/*
-		 * The device might have already been probed during
-		 * the call to device_probe() on its parent device
-		 * (e.g. PCI bridge devices). Test the flags again
-		 * so that we don't mess up the device.
-		 */
-		if (dev_get_flags(dev) & DM_FLAG_PLATDATA_VALID)
-			return 0;
 	}
-
-	ret = device_alloc_priv(dev);
-	if (ret)
-		goto fail;
-
 	drv = dev->driver;
 	assert(drv);
 
diff --git a/dts/Kconfig b/dts/Kconfig
index c39cc368881..d289752a139 100644
--- a/dts/Kconfig
+++ b/dts/Kconfig
@@ -371,6 +371,15 @@ config SPL_OF_PLATDATA_INST
 	  Declare devices as udevice instances so that they do not need to be
 	  bound when U-Boot starts. This can save time and code space.
 
+config SPL_OF_PLATDATA_NO_BIND
+	bool "Don't allow run-time binding of devices"
+	depends on SPL_OF_PLATDATA_INST
+	default y
+	help
+	  This removes the ability to bind devices at run time, thus saving
+	  some code space in U-Boot. This can be disabled if binding is needed,
+	  at the code of some code size increase.
+
 endif
 
 config TPL_OF_PLATDATA
@@ -411,6 +420,15 @@ config TPL_OF_PLATDATA_INST
 	  Declare devices as udevice instances so that they do not need to be
 	  bound when U-Boot starts. This can save time and code space.
 
+config TPL_OF_PLATDATA_NO_BIND
+	bool "Don't allow run-time binding of devices"
+	depends on TPL_OF_PLATDATA_INST
+	default y
+	help
+	  This removes the ability to bind devices at run time, thus saving
+	  some code space in U-Boot. This can be disabled if binding is needed,
+	  at the code of some code size increase.
+
 endif
 
 endmenu
-- 
2.31.0.rc2.261.g7f71774620-goog