[Pdbg] [PATCH v5 05/19] libpdbg: Use PDBG_BACKEND_DRIVER to specify drivers to load

[Amitay Isaacs]

When PDBG_BACKEND_DTB is specified, backend may not be set.  This means
only the drivers registered with PDBG_DEFAULT_BACKEND will be loaded.
To be able to match backend specific drivers for targets in system tree,
use the backend specified in PDBG_BACKEND_DRIVER environment variable.

Signed-off-by: Amitay Isaacs <amitay at ozlabs.org>
---
 libpdbg/dtb.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/libpdbg/dtb.c b/libpdbg/dtb.c
index 70b7962..3b7a597 100644
--- a/libpdbg/dtb.c
+++ b/libpdbg/dtb.c
@@ -76,8 +76,25 @@ static struct pdbg_dtb pdbg_dtb = {
  * running on. */
 static enum pdbg_backend default_backend(void)
 {
+	const char *tmp;
 	int rc;
 
+	tmp = getenv("PDBG_BACKEND_DRIVER");
+	if (tmp) {
+		if (!strcmp(tmp, "fsi"))
+			return PDBG_BACKEND_FSI;
+		else if (!strcmp(tmp, "i2c"))
+			return PDBG_BACKEND_I2C;
+		else if (!strcmp(tmp, "kernel"))
+			return PDBG_BACKEND_KERNEL;
+		else if (!strcmp(tmp, "fake"))
+			return PDBG_BACKEND_FAKE;
+		else if (!strcmp(tmp, "host"))
+			return PDBG_BACKEND_HOST;
+		else if (!strcmp(tmp, "cronus"))
+			return PDBG_BACKEND_CRONUS;
+	}
+
 	rc = access(XSCOM_BASE_PATH, F_OK);
 	if (rc == 0) /* PowerPC Host System */
 		return PDBG_BACKEND_HOST;
@@ -313,6 +330,9 @@ struct pdbg_dtb *pdbg_default_dtb(void *system_fdt)
 	dtb->backend.fdt = NULL;
 	dtb->system.fdt = system_fdt;
 
+	if (!pdbg_backend)
+		pdbg_backend = default_backend();
+
 	fdt = getenv("PDBG_BACKEND_DTB");
 	if (fdt)
 		mmap_dtb(fdt, false, &dtb->backend);
@@ -324,9 +344,6 @@ struct pdbg_dtb *pdbg_default_dtb(void *system_fdt)
 	if (dtb->backend.fdt && dtb->system.fdt)
 		goto done;
 
-	if (!pdbg_backend)
-		pdbg_backend = default_backend();
-
 	switch(pdbg_backend) {
 	case PDBG_BACKEND_HOST:
 		ppc_target(dtb);
-- 
2.25.4