'info fdt' is only able to print full nodes so far. It would be good to
be able to also print single properties, since ometimes we just want
to verify a single value from the FDT.
libfdt does not have support to find a property given its full path, but
it does have a way to return a fdt_property given a prop name and its
subnode.
This is how we're going to support it:
- given the same fullpath parameter, assume it's a node. If we have a
match with an existing node, print it. If not, assume it's a property;
- in fdt_find_property() we're going to split 'fullpath' into node and
property. Unfortunately we can't use g_path_get_basename() to helps us
because, although the device tree path format is similar to Linux, it'll
not work when trying to run QEMU under Windows where the path format is
different;
- after spliiting into node + property, try to find the node in the FDT.
If we have a match, use fdt_get_property() to retrieve fdt_property.
Return it if found;
- using the fdt_print_property() created previously, print the property.
After this change, if an user wants to print just the value of 'cpu' inside
/cpu/cpu-map(...) from an ARM FDT, we can do it:
(qemu) info fdt /cpus/cpu-map/socket0/cluster0/core0/cpu
/cpus/cpu-map/socket0/cluster0/core0/cpu = <0x8001>
(qemu)
Or the 'ibm,my-dma-window' from the v-scsi device inside the pSeries
FDT:
(qemu) info fdt /vdevice/v-scsi@71000003/ibm,my-dma-window
/vdevice/v-scsi@71000003/ibm,my-dma-window = <0x71000003 0x0 0x0 0x0 0x10000000>
(qemu)
Cc: Dr. David Alan Gilbert <dgilb...@redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb...@gmail.com>
---
hmp-commands-info.hx | 2 +-
softmmu/device_tree.c | 79 ++++++++++++++++++++++++++++++++++++++++---
2 files changed, 76 insertions(+), 5 deletions(-)
diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
index abf277be7d..8891c2918a 100644
--- a/hmp-commands-info.hx
+++ b/hmp-commands-info.hx
@@ -913,7 +913,7 @@ ERST
.name = "fdt",
.args_type = "fullpath:s",
.params = "fullpath",
- .help = "show firmware device tree node given its full path",
+ .help = "show firmware device tree node or property given its
full path",
.cmd = hmp_info_fdt,
},
diff --git a/softmmu/device_tree.c b/softmmu/device_tree.c
index e41894fbef..f6eb060acc 100644
--- a/softmmu/device_tree.c
+++ b/softmmu/device_tree.c
@@ -774,9 +774,74 @@ static void fdt_print_node(int node, int depth, const char
*fullpath)
qemu_printf("%*s}\n", padding, "");
}
+static const struct fdt_property *fdt_find_property(const char *fullpath,
+ int *prop_size,
+ Error **errp)
+{
+ const struct fdt_property *prop = NULL;
+ void *fdt = current_machine->fdt;
+ g_autoptr(GString) nodename = NULL;
+ const char *propname = NULL;
+ int path_len = strlen(fullpath);
+ int node = 0; /* default to root node '/' */
+ int i, idx = -1;
+
+ /*
+ * We'll assume that we're dealing with a property. libfdt
+ * does not have an API to find a property given the full
+ * path, but it does have an API to find a property inside
+ * a node.
+ */
+ nodename = g_string_new("");
+
+ for (i = path_len - 1; i >= 0; i--) {
+ if (fullpath[i] == '/') {
+ idx = i;
+ break;
+ }
+ }
+
+ if (idx == -1) {
+ error_setg(errp, "FDT paths must contain at least one '/' character");
+ return NULL;
+ }
+
+ if (idx == path_len - 1) {
+ error_setg(errp, "FDT paths can't end with a '/' character");
+ return NULL;
+ }
+
+ propname = &fullpath[idx + 1];
+
+ if (idx != 0) {
+ g_string_append_len(nodename, fullpath, idx);
+
+ node = fdt_path_offset(fdt, nodename->str);
+ if (node < 0) {
+ error_setg(errp, "node '%s' of property '%s' not found in FDT",
+ nodename->str, propname);
+ return NULL;
+ }
+ } else {
+ /* idx = 0 means that it's a property of the root node */
+ g_string_append(nodename, "/");
+ }
+
+ prop = fdt_get_property(fdt, node, propname, prop_size);
+ if (!prop) {
+ error_setg(errp, "property '%s' not found in node '%s' in FDT",
+ propname, nodename->str);
+ return NULL;
+ }
+
+ return prop;
+}
+
void fdt_info(const char *fullpath, Error **errp)
{
- int node;
+ const struct fdt_property *prop = NULL;
+ Error *local_err = NULL;
+ int node, prop_size;
if (!current_machine->fdt) {
error_setg(errp, "Unable to find the machine FDT");
@@ -784,10 +849,16 @@ void fdt_info(const char *fullpath, Error **errp)
}
node = fdt_path_offset(current_machine->fdt, fullpath);
- if (node < 0) {
- error_setg(errp, "node '%s' not found in FDT", fullpath);
+ if (node >= 0) {
+ fdt_print_node(node, 0, fullpath);
+ return;
+ }
+
+ prop = fdt_find_property(fullpath, &prop_size, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
return;
}
- fdt_print_node(node, 0, fullpath);
+ fdt_print_property(fullpath, prop->data, prop_size, 0);
}
--
2.36.1
