[U-Boot] [RFC PATCH 2/3] dm: core: Add dm_pre_os_remove() and hook it into device_remove()

[Stefan Roese]

The new function dm_pre_os_remove() is intented for driver specific
last-stage cleanup operations before the OS is started. This patch adds
this functionality and hooks it into the common device_remove()
function.

To enable usage for custom driver (e.g. ethernet drivers), this patch
also sets the pre-OS remove flag for the root driver and simple-bus
drivers. Otherwise the recursive call starting from the root device
would not reach the drivers in need for this specific remove call.

Signed-off-by: Stefan Roese <sr at denx.de>
Cc: Simon Glass <sjg at chromium.org>
---
 drivers/core/device-remove.c | 7 +++++++
 drivers/core/root.c          | 8 ++++++++
 drivers/core/simple-bus.c    | 1 +
 include/dm/root.h            | 9 +++++++++
 4 files changed, 25 insertions(+)

diff --git a/drivers/core/device-remove.c b/drivers/core/device-remove.c
index 4725d4751c..0dfb20cdce 100644
--- a/drivers/core/device-remove.c
+++ b/drivers/core/device-remove.c
@@ -166,6 +166,13 @@ int device_remove(struct udevice *dev, bool pre_os_remove)
 	drv = dev->driver;
 	assert(drv);
 
+	/*
+	 * If pre-OS remove is requested, only continue for drivers with this
+	 * flag set
+	 */
+	if (pre_os_remove && !(drv->flags & DM_FLAG_PRE_OS_REMOVE))
+		return 0;
+
 	ret = uclass_pre_remove_device(dev);
 	if (ret)
 		return ret;
diff --git a/drivers/core/root.c b/drivers/core/root.c
index 583daa88b0..1468a15db4 100644
--- a/drivers/core/root.c
+++ b/drivers/core/root.c
@@ -182,6 +182,13 @@ int dm_uninit(void)
 	return 0;
 }
 
+int dm_pre_os_remove(void)
+{
+	device_remove(dm_root(), true);
+
+	return 0;
+}
+
 int dm_scan_platdata(bool pre_reloc_only)
 {
 	int ret;
@@ -280,6 +287,7 @@ U_BOOT_DRIVER(root_driver) = {
 	.name	= "root_driver",
 	.id	= UCLASS_ROOT,
 	.priv_auto_alloc_size = sizeof(struct root_priv),
+	.flags	= DM_FLAG_PRE_OS_REMOVE,
 };
 
 /* This is the root uclass */
diff --git a/drivers/core/simple-bus.c b/drivers/core/simple-bus.c
index a300217d39..4142626ff6 100644
--- a/drivers/core/simple-bus.c
+++ b/drivers/core/simple-bus.c
@@ -64,4 +64,5 @@ U_BOOT_DRIVER(simple_bus_drv) = {
 	.name	= "generic_simple_bus",
 	.id	= UCLASS_SIMPLE_BUS,
 	.of_match = generic_simple_bus_ids,
+	.flags	= DM_FLAG_PRE_OS_REMOVE,
 };
diff --git a/include/dm/root.h b/include/dm/root.h
index 3cf730dcee..8ac7bc3512 100644
--- a/include/dm/root.h
+++ b/include/dm/root.h
@@ -115,4 +115,13 @@ int dm_init(void);
  */
 int dm_uninit(void);
 
+/**
+ * dm_pre_os_remove - Call remove function of all drivers with the pre-OS
+ *		      remove flag set
+ *
+ * All devices with the pre-OS remove flag set, will be removed
+ * @return 0 if OK, -ve on error
+ */
+int dm_pre_os_remove(void);
+
 #endif
-- 
2.12.0