From 730875016a6a94bd43e4e88b34a73a814e1051e7 Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Tue, 26 Mar 2019 16:33:02 +0100 Subject: libfdt: Add phandle generation helper 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 Message-Id: <20190326153302.17109-3-thierry.reding@gmail.com> Signed-off-by: David Gibson --- libfdt/fdt_ro.c | 18 ++++++++++++++++++ libfdt/libfdt.h | 19 +++++++++++++++++++ libfdt/version.lds | 1 + tests/get_phandle.c | 30 +++++++++++++++++++++++++++++- tests/multilabel.dts | 5 +++++ tests/multilabel_merge.dts | 5 +++++ tests/references.c | 19 +++++++++++++++++-- tests/references.dts | 5 +++++ 8 files changed, 99 insertions(+), 3 deletions(-) diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c index 1d0335e..817ac39 100644 --- a/libfdt/fdt_ro.c +++ b/libfdt/fdt_ro.c @@ -184,6 +184,24 @@ uint32_t fdt_get_max_phandle(const void *fdt) return phandle; } +int fdt_generate_phandle(const void *fdt, uint32_t *phandle) +{ + uint32_t max; + int err; + + err = fdt_find_max_phandle(fdt, &max); + if (err < 0) + return err; + + 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 e1498c3..39ff6d5 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) */ /**********************************************************************/ @@ -416,6 +420,21 @@ int fdt_find_max_phandle(const void *fdt, uint32_t *phandle); */ 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/version.lds b/libfdt/version.lds index 87bbb2f..a8422af 100644 --- a/libfdt/version.lds +++ b/libfdt/version.lds @@ -68,6 +68,7 @@ LIBFDT_1.2 { fdt_get_string; fdt_find_max_phandle; fdt_get_max_phandle; + fdt_generate_phandle; fdt_check_full; fdt_setprop_placeholder; fdt_property_placeholder; diff --git a/tests/get_phandle.c b/tests/get_phandle.c index 6973ee4..e97b49c 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 #include #include #include @@ -42,9 +43,30 @@ 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; @@ -68,5 +90,11 @@ 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 77da06c..d80ebe1 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 3e80298..a27d856 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 cab70f6..5b233a4 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 f783e8b..b390639 100644 --- a/tests/references.dts +++ b/tests/references.dts @@ -33,4 +33,9 @@ linux,phandle = <&n5>; phandle = <&n5>; }; + + node6 { + linux,phandle = <0xfffffffe>; + phandle = <0xfffffffe>; + }; }; -- cgit v1.2.1