Add fdtget utility to read property values from a device tree

This simply utility makes it easy for scripts to read values from the device
tree. It is written in C and uses the same libfdt as the rest of the dtc
package.

What is it for:
- Reading fdt values from scripts
- Extracting fdt information within build systems
- Looking at particular values without having to dump the entire tree

To use it, specify the fdt binary file on command line followed by a list of
node, property pairs. The utility then looks up each node, finds the property
and displays the value.

Each value is printed on a new line.

fdtget tries to guess the type of each property based on its contents. This
is not always reliable, so you can use the -t option to force fdtget to decode
the value as a string, or byte, etc.

To read from stdin, use - as the file.

Usage:
	fdtget <options> <dt file> [<node> <property>]...
Options:
	-t <type>	Type of data
	-h		Print this help

<type>	s=string, i=int, u=unsigned, x=hex
	Optional modifier prefix:
		hh or b=byte, h=2 byte, l=4 byte (default)

Signed-off-by: Simon Glass <sjg@chromium.org>

3 files changed, 78 insertions, 1 deletions

diff --git a/tests/fdtget-runtest.sh b/tests/fdtget-runtest.sh
new file mode 100755
index 0000000..f38184f
--- /dev/null
+++ b/tests/fdtget-runtest.sh
@@ -0,0 +1,35 @@
+#! /bin/sh
+
+. ./tests.sh
+
+LOG="tmp.log.$$"
+EXPECT="tmp.expect.$$"
+
+rm -f $TMPFILE $LOG
+
+expect="$1"
+echo "$expect" >$EXPECT
+shift
+
+verbose_run_log "$LOG" $VALGRIND "$DTGET" "$@"
+ret="$?"
+
+if [ "$ret" -ne 0 -a "$expect" = "ERR" ]; then
+	PASS
+fi
+
+if [ "$ret" -gt 127 ]; then
+    signame=$(kill -l $[ret - 128])
+    FAIL "Killed by SIG$signame"
+fi
+
+diff $EXPECT $LOG
+ret="$?"
+
+rm -f $LOG $EXPECT
+
+if [ "$ret" -eq 0 ]; then
+	PASS
+else
+	FAIL
+fi
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index e42154b..e6184df 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -83,6 +83,13 @@ asm_to_so_test () {
     run_wrap_test asm_to_so "$@"
 }
 
+run_fdtget_test () {
+    # run_fdtget_test name expected_output dtb_file args...
+    echo -n "$1:	"
+    shift
+    base_run_test sh fdtget-runtest.sh "$@"
+}
+
 tree1_tests () {
     TREE=$1
 
@@ -402,6 +409,37 @@ dtbs_equal_tests () {
     cmp_tests test_tree1.dtb $WRONG_TREE1
 }
 
+fdtget_tests () {
+    file=label01.dtb
+    $DTC -O dtb -o $file ${file%.dtb}.dts 2>/dev/null
+
+    # run_fdtget_test <test-name> <expected-result> <args>...
+    run_fdtget_test "Simple string" "MyBoardName" $file / model
+    run_fdtget_test "Multiple string i" "77 121 66 111 \
+97 114 100 78 97 109 101 0 77 121 66 111 97 114 100 70 97 109 105 \
+108 121 78 97 109 101 0" $file / compatible
+    run_fdtget_test "Multiple string s" "MyBoardName MyBoardFamilyName" \
+	-t s $file / compatible
+    run_fdtget_test "Integer" "32768" $file /cpus/PowerPC,970@1 d-cache-size
+    run_fdtget_test "Integer hex" "8000" -tx $file \
+	/cpus/PowerPC,970@1 d-cache-size
+    run_fdtget_test "Integer list" "61 62 63 0" -tbx $file \
+	/randomnode tricky1
+    run_fdtget_test "Byte list short" "a b c d de ea ad be ef" -tbx \
+	$file /randomnode blob
+
+    # Here the property size is not a multiple of 4 bytes, so it should fail
+    run_fdtget_test "Integer list invalid" ERR -tlx \
+	$file /randomnode mixed
+    run_fdtget_test "Integer list halfword" "6162 6300 1234 0 a 0 b 0 c" -thx \
+	$file /randomnode mixed
+    run_fdtget_test "Integer list byte" \
+	"61 62 63 0 12 34 0 0 0 a 0 0 0 b 0 0 0 c" -thhx \
+	$file /randomnode mixed
+    run_fdtget_test "Missing property" ERR -ts \
+	$file /randomnode doctor-who
+}
+
 utilfdt_tests () {
     run_test utilfdt_test
 }
@@ -421,7 +459,7 @@ while getopts "vt:m" ARG ; do
 done
 
 if [ -z "$TESTSETS" ]; then
-    TESTSETS="libfdt utilfdt dtc dtbs_equal"
+    TESTSETS="libfdt utilfdt dtc dtbs_equal fdtget"
 fi
 
 # Make sure we don't have stale blobs lying around
@@ -441,6 +479,9 @@ for set in $TESTSETS; do
 	"dtbs_equal")
 	    dtbs_equal_tests
 	    ;;
+	"fdtget")
+	    fdtget_tests
+	    ;;
     esac
 done
 
diff --git a/tests/tests.sh b/tests/tests.sh
index 30ffead..d9a0524 100644
--- a/tests/tests.sh
+++ b/tests/tests.sh
@@ -11,6 +11,7 @@ FAIL () {
 }
 
 DTC=../dtc
+DTGET=../fdtget
 
 verbose_run () {
     if [ -z "$QUIET_TEST" ]; then