[Pdbg] [PATCH v3 04/16] libpdbg: Add indirect address translation via callback

[Alistair Popple]

Some hardware targets have more complicated addressing schemes than a
simple base address + offset. It may be possible to determine a
device-tree representation for these schemes but for the moment it is
more straight forward to define a callback to do the translation.

Signed-off-by: Alistair Popple <alistair at popple.id.au>
Reviewed-by: Amitay Isaacs <amitay at ozlabs.org>
---
 libpdbg/target.c | 7 ++++++-
 libpdbg/target.h | 7 +++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/libpdbg/target.c b/libpdbg/target.c
index 975ecec..7468863 100644
--- a/libpdbg/target.c
+++ b/libpdbg/target.c
@@ -20,8 +20,13 @@ static struct pdbg_target *get_class_target_addr(struct pdbg_target *target, con
 {
 	/* Check class */
 	while (strcmp(target->class, name)) {
+
+		if (target->translate)
+			*addr = target->translate(target, *addr);
+		else
+			*addr += dt_get_address(target, 0, NULL);
+
 		/* Keep walking the tree translating addresses */
-		*addr += dt_get_address(target, 0, NULL);
 		target = target->parent;
 
 		/* The root node doesn't have an address space so it's
diff --git a/libpdbg/target.h b/libpdbg/target.h
index d1a6aec..289c1ee 100644
--- a/libpdbg/target.h
+++ b/libpdbg/target.h
@@ -38,6 +38,7 @@ struct pdbg_target {
 	char *class;
 	int (*probe)(struct pdbg_target *target);
 	void (*release)(struct pdbg_target *target);
+	uint64_t (*translate)(struct pdbg_target *target, uint64_t addr);
 	int index;
 	enum pdbg_target_status status;
 	const char *dn_name;
@@ -57,6 +58,12 @@ struct pdbg_target_class *require_target_class(const char *name);
 struct pdbg_target_class *get_target_class(const char *name);
 bool pdbg_target_is_class(struct pdbg_target *target, const char *class);
 
+/* This works and should be safe because struct pdbg_target is guaranteed to be
+ * the first member of the specialised type (see the DECLARE_HW_UNIT definition
+ * below). I'm not sure how sane it is though. Probably not very but it does
+ * remove a bunch of tedious container_of() typing */
+#define translate_cast(x) (uint64_t (*)(struct pdbg_target *, uint64_t)) (x)
+
 extern struct list_head empty_list;
 extern struct list_head target_classes;
 
-- 
2.11.0