On 11/04/2025 14:47, Caleb Connolly wrote:
OF_LIVE offers a variety of benefits, one of them being that the live
tree can be modified without caring about the underlying FDT. This is
particularly valuable for working around U-Boot limitations like lacking
USB superspeed support on Qualcomm platforms, no runtime OTG, or
peripherals like the sdcard being broken (and displaying potentially
worrying error messages).
Add an event to signal when the live tree has been built so that we can
apply fixups to it directly before devices are bound.
Signed-off-by: Caleb Connolly <caleb.conno...@linaro.org>
---
common/event.c | 3 +++
include/event.h | 18 ++++++++++++++++++
lib/of_live.c | 11 +++++++++++
3 files changed, 32 insertions(+)
diff --git a/common/event.c b/common/event.c
index
dda569d447851f559a83f98fb7b1f3543156eab5..8d7513eb10b61919e1e784481dfdcc076be14986
100644
--- a/common/event.c
+++ b/common/event.c
@@ -47,8 +47,11 @@ const char *const type_name[] = {
"ft_fixup",
/* main loop events */
"main_loop",
+
+ /* livetree has been built */
+ "of_live_init",
"of_live_built" ?
};
_Static_assert(ARRAY_SIZE(type_name) == EVT_COUNT, "event type_name size");
#endif
diff --git a/include/event.h b/include/event.h
index
75141a192a48b0931667632f41be8ff4d6139f7c..1d267f1d10547642d381fa287ab4981a2bf03543
100644
--- a/include/event.h
+++ b/include/event.h
@@ -152,8 +152,17 @@ enum event_t {
* A non-zero return value causes the boot to fail.
*/
EVT_MAIN_LOOP,
+ /**
+ * @EVT_OF_LIVE_BUILT:
+ * This event is triggered immediately after the live device tree has
been
+ * built. This allows for machine specific fixups to be done to the
live tree
+ * (like disabling known-unsupported devices) before it is used. This
+ * event is only available if OF_LIVE is enabled and is only used after
relocation.
+ */
+ EVT_OF_LIVE_BUILT,
+
/**
* @EVT_COUNT:
* This constants holds the maximum event number + 1 and is used when
* looping over all event classes.
@@ -202,8 +211,17 @@ union event_data {
struct event_ft_fixup {
oftree tree;
struct bootm_headers *images;
} ft_fixup;
+
+ /**
+ * struct event_of_live_built - livetree has been built
+ *
+ * @root: The root node of the live device tree
+ */
+ struct event_of_live_built {
+ struct device_node *root;
+ } of_live_built;
};
/**
* struct event - an event that can be sent and received
diff --git a/lib/of_live.c b/lib/of_live.c
index
90b9459ede313e492e28c8556c730f3bd8aaa9df..c1620616513c2e32448b4a6d156a9162d97c76b7
100644
--- a/lib/of_live.c
+++ b/lib/of_live.c
@@ -10,8 +10,9 @@
#define LOG_CATEGORY LOGC_DT
#include <abuf.h>
+#include <event.h>
#include <log.h>
#include <linux/libfdt.h>
#include <of_live.h>
#include <malloc.h>
@@ -320,8 +321,9 @@ int unflatten_device_tree(const void *blob, struct
device_node **mynodes)
int of_live_build(const void *fdt_blob, struct device_node **rootp)
{
int ret;
+ union event_data evt;
debug("%s: start\n", __func__);
ret = unflatten_device_tree(fdt_blob, rootp);
if (ret) {
@@ -334,8 +336,17 @@ int of_live_build(const void *fdt_blob, struct device_node
**rootp)
return ret;
}
debug("%s: stop\n", __func__);
+ if (CONFIG_IS_ENABLED(EVENT)) {
+ evt.of_live_built.root = *rootp;
+ ret = event_notify(EVT_OF_LIVE_BUILT, &evt, sizeof(evt));
+ if (ret) {
+ log_debug("Failed to notify livetree build event:
err=%d\n", ret);
+ return ret;
+ }
+ }
+
return ret;
}
void of_live_free(struct device_node *root)
