From: Thierry Reding <treding@xxxxxxxxxx>
The new fdt_generate_phandle() function can be used to generate a new,
unused phandle given a specific device tree blob. The implementation is
somewhat naive in that it simply walks the entire device tree to find
the highest phandle value and then returns a phandle value one higher
than that. A more clever implementation might try to find holes in the
current set of phandle values and fill them. But this implementation is
relatively simple and works reliably.
Also add a test that validates that phandles generated by this new API
are indeed unique.
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
---
Changes in v2:
- Handle the case where the number of phandles has been exhausted. Also
add more testing to exercise this corner case. Note that this is tied
to the current, naive implementation of fdt_generate_phandle(). If it
is ever changed to be more clevel, the tests will have to be updated.
---
libfdt/fdt_ro.c | 31 +++++++++++++++++++++++++++++++
libfdt/libfdt.h | 19 +++++++++++++++++++
libfdt/libfdt_env.h | 1 +
tests/get_phandle.c | 31 ++++++++++++++++++++++++++++++-
tests/multilabel.dts | 5 +++++
tests/multilabel_merge.dts | 5 +++++
tests/references.c | 19 +++++++++++++++++--
tests/references.dts | 5 +++++
8 files changed, 113 insertions(+), 3 deletions(-)
diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
index eafc14282892..97cdcda0dbec 100644
--- a/libfdt/fdt_ro.c
+++ b/libfdt/fdt_ro.c
@@ -170,6 +170,37 @@ uint32_t fdt_get_max_phandle(const void *fdt)
return 0;
}
+int fdt_generate_phandle(const void *fdt, uint32_t *phandle)
+{
+ uint32_t max = 0;
+ int offset = -1;
+
+ while (true) {
+ uint32_t value;
+
+ offset = fdt_next_node(fdt, offset, NULL);
+ if (offset < 0) {
+ if (offset == -FDT_ERR_NOTFOUND)
+ break;
+
+ return offset;
+ }
+
+ value = fdt_get_phandle(fdt, offset);
+
+ if (value > max)
+ max = value;
+ }
+
+ if (max == FDT_MAX_PHANDLE)
+ return -FDT_ERR_NOPHANDLES;
+
+ if (phandle)
+ *phandle = max + 1;
+
+ return 0;
+}
+
static const struct fdt_reserve_entry *fdt_mem_rsv(const void *fdt, int n)
{
int offset = n * sizeof(struct fdt_reserve_entry);
diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
index a470d1df6d2a..7e102d188e86 100644
--- a/libfdt/libfdt.h
+++ b/libfdt/libfdt.h
@@ -140,6 +140,10 @@
#define FDT_ERR_MAX 17
+/* constants */
+#define FDT_MAX_PHANDLE 0xfffffffe
+ /* Valid values for phandles range from 1 to 2^32-2. */
+
/**********************************************************************/
/* Low-level functions (you probably don't need these) */
/**********************************************************************/
@@ -376,6 +380,21 @@ const char *fdt_string(const void *fdt, int stroffset);
*/
uint32_t fdt_get_max_phandle(const void *fdt);
+/**
+ * fdt_generate_phandle - return a new, unused phandle for a device tree blob
+ * @fdt: pointer to the device tree blob
+ * @phandle: return location for the new phandle
+ *
+ * Walks the device tree blob and looks for the highest phandle value. On
+ * success, the new, unused phandle value (one higher than the previously
+ * highest phandle value in the device tree blob) will be returned in the
+ * @phandle parameter.
+ *
+ * Returns:
+ * 0 on success or a negative error-code on failure
+ */
+int fdt_generate_phandle(const void *fdt, uint32_t *phandle);
+
/**
* fdt_num_mem_rsv - retrieve the number of memory reserve map entries
* @fdt: pointer to the device tree blob
diff --git a/libfdt/libfdt_env.h b/libfdt/libfdt_env.h
index eb2053845c9c..4d1cdfa58547 100644
--- a/libfdt/libfdt_env.h
+++ b/libfdt/libfdt_env.h
@@ -52,6 +52,7 @@
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
+#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
diff --git a/tests/get_phandle.c b/tests/get_phandle.c
index 22bd7b81b3f0..d87aee50b065 100644
--- a/tests/get_phandle.c
+++ b/tests/get_phandle.c
@@ -17,6 +17,7 @@
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
+#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
@@ -42,10 +43,32 @@ static void check_phandle(void *fdt, const char *path, uint32_t checkhandle)
path, phandle, checkhandle);
}
+static void check_phandle_unique(const void *fdt, uint32_t checkhandle)
+{
+ uint32_t phandle;
+ int offset = -1;
+
+ while (true) {
+ offset = fdt_next_node(fdt, offset, NULL);
+ if (offset < 0) {
+ if (offset == -FDT_ERR_NOTFOUND)
+ break;
+
+ FAIL("error looking for phandle %#x", checkhandle);
+ }
+
+ phandle = fdt_get_phandle(fdt, offset);
+
+ if (phandle == checkhandle)
+ FAIL("generated phandle already exists");
+ }
+}
+
int main(int argc, char *argv[])
{
- uint32_t max;
+ uint32_t max, phandle;
void *fdt;
+ int err;
test_init(argc, argv);
fdt = load_blob_arg(argc, argv);
@@ -59,5 +82,11 @@ int main(int argc, char *argv[])
FAIL("fdt_get_max_phandle returned 0x%x instead of 0x%x\n",
max, PHANDLE_2);
+ err = fdt_generate_phandle(fdt, &phandle);
+ if (err < 0)
+ FAIL("failed to generate phandle: %d", err);
+
+ check_phandle_unique(fdt, phandle);
+
PASS();
}
diff --git a/tests/multilabel.dts b/tests/multilabel.dts
index 77da06cc4174..d80ebe1fb082 100644
--- a/tests/multilabel.dts
+++ b/tests/multilabel.dts
@@ -41,4 +41,9 @@ m1: mq: /memreserve/ 0 0x1000;
n2 = &n2;
n3 = &n3;
};
+
+ node6 {
+ linux,phandle = <0xfffffffe>;
+ phandle = <0xfffffffe>;
+ };
};
diff --git a/tests/multilabel_merge.dts b/tests/multilabel_merge.dts
index 3e8029897405..a27d856f80dd 100644
--- a/tests/multilabel_merge.dts
+++ b/tests/multilabel_merge.dts
@@ -39,6 +39,11 @@ m1: mq: /memreserve/ 0 0x1000;
n2 = &n2;
n3 = &n3;
};
+
+ node6 {
+ linux,phandle = <0xfffffffe>;
+ phandle = <0xfffffffe>;
+ };
};
/ {
diff --git a/tests/references.c b/tests/references.c
index cab70f6579af..5b233a4bda20 100644
--- a/tests/references.c
+++ b/tests/references.c
@@ -76,8 +76,8 @@ static void check_rref(const void *fdt)
int main(int argc, char *argv[])
{
void *fdt;
- int n1, n2, n3, n4, n5;
- uint32_t h1, h2, h4, h5;
+ int n1, n2, n3, n4, n5, n6, err;
+ uint32_t h1, h2, h4, h5, h6, hn;
test_init(argc, argv);
fdt = load_blob_arg(argc, argv);
@@ -97,11 +97,15 @@ int main(int argc, char *argv[])
n5 = fdt_path_offset(fdt, "/node5");
if (n5 < 0)
FAIL("fdt_path_offset(/node5): %s", fdt_strerror(n5));
+ n6 = fdt_path_offset(fdt, "/node6");
+ if (n6 < 0)
+ FAIL("fdt_path_offset(/node6): %s", fdt_strerror(n6));
h1 = fdt_get_phandle(fdt, n1);
h2 = fdt_get_phandle(fdt, n2);
h4 = fdt_get_phandle(fdt, n4);
h5 = fdt_get_phandle(fdt, n5);
+ h6 = fdt_get_phandle(fdt, n6);
if (h1 != 0x2000)
FAIL("/node1 has wrong phandle, 0x%x instead of 0x%x",
@@ -109,6 +113,9 @@ int main(int argc, char *argv[])
if (h2 != 0x1)
FAIL("/node2 has wrong phandle, 0x%x instead of 0x%x",
h2, 0x1);
+ if (h6 != FDT_MAX_PHANDLE)
+ FAIL("/node6 has wrong phandle, 0x%x instead of 0x%x",
+ h6, FDT_MAX_PHANDLE);
if ((h4 == 0x2000) || (h4 == 0x1) || (h4 == 0))
FAIL("/node4 has bad phandle, 0x%x", h4);
@@ -117,6 +124,14 @@ int main(int argc, char *argv[])
if ((h5 == h4) || (h5 == h2) || (h5 == h1))
FAIL("/node5 has duplicate phandle, 0x%x", h5);
+ /*
+ * /node6 has phandle FDT_MAX_PHANDLE, so fdt_generate_phandle() is
+ * expected to fail.
+ */
+ err = fdt_generate_phandle(fdt, &hn);
+ if (err != -FDT_ERR_NOPHANDLES)
+ FAIL("generated invalid phandle 0x%x\n", hn);
+
check_ref(fdt, n1, h2);
check_ref(fdt, n2, h1);
check_ref(fdt, n3, h4);
diff --git a/tests/references.dts b/tests/references.dts
index f783e8bc8643..b39063999189 100644
--- a/tests/references.dts
+++ b/tests/references.dts
@@ -33,4 +33,9 @@
linux,phandle = <&n5>;
phandle = <&n5>;
};
+
+ node6 {
+ linux,phandle = <0xfffffffe>;
+ phandle = <0xfffffffe>;
+ };
};
--
2.21.0
