scripts/dtc: dt_to_config - kernel config options for a devicetree

Determining which kernel config options need to be enabled for a
given devicetree can be a painful process.  Create a new tool to
find the drivers that may match a devicetree node compatible,
find the kernel config options that enable the driver, and
optionally report whether the kernel config option is enabled.

Signed-off-by: Gaurav Minocha <gaurav.minocha.os@gmail.com>
Signed-off-by: Frank Rowand <frank.rowand@am.sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>

2 files changed, 1214 insertions, 1 deletions

diff --git a/scripts/dtc/dt_to_config b/scripts/dtc/dt_to_config
new file mode 100755
index 000000000000..9a248b505c58
--- /dev/null
+++ b/scripts/dtc/dt_to_config
@@ -0,0 +1,1213 @@
+#!/usr/bin/perl
+
+# Copyright 2016 by Frank Rowand
+# Copyright 2016 by Gaurav Minocha
+#
+# This file is subject to the terms and conditions of the GNU General Public
+# License v2.
+
+use strict 'refs';
+use strict subs;
+
+use Getopt::Long;
+
+$VUFX = "160610a";
+
+$script_name = $0;
+$script_name =~ s|^.*/||;
+
+
+# ----- constants for print_flags()
+
+# Position in string $pr_flags.  Range of 0..($num_pr_flags - 1).
+$pr_flag_pos_mcompatible       = 0;
+$pr_flag_pos_driver            = 1;
+$pr_flag_pos_mdriver           = 2;
+$pr_flag_pos_config            = 3;
+$pr_flag_pos_mconfig           = 4;
+$pr_flag_pos_node_not_enabled  = 5;
+$pr_flag_pos_white_list        = 6;
+$pr_flag_pos_hard_coded        = 7;
+$pr_flag_pos_config_hard_coded = 8;
+$pr_flag_pos_config_none       = 9;
+$pr_flag_pos_config_m          = 10;
+$pr_flag_pos_config_y          = 11;
+$pr_flag_pos_config_test_fail  = 12;
+
+$num_pr_flags = $pr_flag_pos_config_test_fail + 1;
+
+# flags in @pr_flag_value must be unique values to allow simple regular
+# expessions to work for --include_flags and --exclude_flags.
+# Convention: use upper case letters for potential issues or problems.
+
+@pr_flag_value = ('M', 'd', 'D', 'c', 'C', 'E', 'W', 'H', 'x', 'n', 'm', 'y', 'F');
+
+@pr_flag_help = (
+    "multiple compatibles found for this node",
+    "driver found for this compatible",
+    "multiple drivers found for this compatible",
+    "kernel config found for this driver",
+    "multiple config options found for this driver",
+    "node is not enabled",
+    "compatible is white listed",
+    "matching driver and/or kernel config is hard coded",
+    "kernel config hard coded in Makefile",
+    "one or more kernel config file options is not set",
+    "one or more kernel config file options is set to 'm'",
+    "one or more kernel config file options is set to 'y'",
+    "one of more kernel config file options fails to have correct value"
+);
+
+
+# -----
+
+%driver_config = ();   # driver config array, indexed by driver source file
+%driver_count = ();    # driver_cnt, indexed by compatible
+%compat_driver = ();   # compatible driver array, indexed by compatible
+%existing_config = (); # existing config symbols present in given config file
+                       # expected values are: "y", "m", a decimal number, a
+                       # hex number, or a string
+
+# ----- magic compatibles, do not have a driver
+#
+# Will not search for drivers for these compatibles.
+
+%compat_white_list = (
+       'none'                  => '1',
+       'pci'                   => '1',
+       'simple-bus'            => '1',
+);
+
+# Will not search for drivers for these compatibles.
+#
+# These compatibles have a very large number of false positives.
+#
+# 'hardcoded_no_driver' is a magic value.  Other code knows this
+# magic value.  Do not use 'no_driver' here!
+#
+# Revisit each 'hardcoded_no_driver' to see how the compatible
+# is used.  Are there drivers that can be provided?
+
+%driver_hard_code_list = (
+       'cache'                 => ['hardcoded_no_driver'],
+       'eeprom'                => ['hardcoded_no_driver'],
+       'gpio'                  => ['hardcoded_no_driver'],
+       'gpio-keys'             => ['drivers/input/keyboard/gpio_keys.c'],
+       'i2c-gpio'              => ['drivers/i2c/busses/i2c-gpio.c'],
+       'isa'                   => ['arch/mips/mti-malta/malta-dt.c',
+                                    'arch/x86/kernel/devicetree.c'],
+       'led'                   => ['hardcoded_no_driver'],
+       'm25p32'                => ['hardcoded_no_driver'],
+       'm25p64'                => ['hardcoded_no_driver'],
+       'm25p80'                => ['hardcoded_no_driver'],
+       'mtd-ram'               => ['drivers/mtd/maps/physmap_of.c'],
+       'pwm-backlight'         => ['drivers/video/backlight/pwm_bl.c'],
+       'spidev'                => ['hardcoded_no_driver'],
+       'syscon'                => ['drivers/mfd/syscon.c'],
+       'tlv320aic23'           => ['hardcoded_no_driver'],
+       'wm8731'                => ['hardcoded_no_driver'],
+);
+
+# Use these config options instead of searching makefiles
+
+%driver_config_hard_code_list = (
+
+       # this one needed even if %driver_hard_code_list is empty
+       'no_driver'                             => ['no_config'],
+       'hardcoded_no_driver'                   => ['no_config'],
+
+       # drivers/usb/host/ehci-ppc-of.c
+       # drivers/usb/host/ehci-xilinx-of.c
+       #  are included from:
+       #    drivers/usb/host/ehci-hcd.c
+       #  thus the search of Makefile for the included .c files is incorrect
+       # ehci-hcd.c wraps the includes with ifdef CONFIG_USB_EHCI_HCD_..._OF
+       #
+       # similar model for ohci-hcd.c (but no ohci-xilinx-of.c)
+       #
+       # similarly, uhci-hcd.c includes uhci-platform.c
+
+       'drivers/usb/host/ehci-ppc-of.c'        => ['CONFIG_USB_EHCI_HCD',
+                                                   'CONFIG_USB_EHCI_HCD_PPC_OF'],
+       'drivers/usb/host/ohci-ppc-of.c'        => ['CONFIG_USB_OHCI_HCD',
+                                                   'CONFIG_USB_OHCI_HCD_PPC_OF'],
+
+       'drivers/usb/host/ehci-xilinx-of.c'     => ['CONFIG_USB_EHCI_HCD',
+                                                   'CONFIG_USB_EHCI_HCD_XILINX'],
+
+       'drivers/usb/host/uhci-platform.c'      => ['CONFIG_USB_UHCI_HCD',
+                                                   'CONFIG_USB_UHCI_PLATFORM'],
+
+       # scan_makefile will find only one of these config options:
+       #    ifneq ($(CONFIG_SOC_IMX6)$(CONFIG_SOC_LS1021A),)
+       'arch/arm/mach-imx/platsmp.c'           => ['CONFIG_SOC_IMX6 && CONFIG_SMP',
+                                                   'CONFIG_SOC_LS1021A && CONFIG_SMP'],
+);
+
+
+# 'virt/kvm/arm/.*' are controlled by makefiles in other directories,
+# using relative paths, such as 'KVM := ../../../virt/kvm'.  Do not
+# add complexity to find_kconfig() to deal with this.  There is a long
+# term intent to change the kvm related makefiles to the normal kernel
+# style.  After that is done, this entry can be removed from the
+# black_list_driver.
+
+@black_list_driver = (
+       # kvm no longer a problem after commit 503a62862e8f in 4.7-rc1
+       # 'virt/kvm/arm/.*',
+);
+
+
+sub usage()
+{
+       print
+"
+Usage: $script_name [options] device-tree...
+
+    device_tree is: dts_file | dtb_file | proc_device-tree
+
+
+Valid options:
+     -c FILE             Read kernel config options from FILE
+    --config FILE        synonym for 'c'
+    --config-format      config file friendly output format
+    --exclude-flag FLAG  exclude entries with a matching flag
+     -h                  Display this message and exit
+    --help               synonym for 'h'
+    --black-list-driver  use driver black list
+    --white-list-config  use config white list
+    --white-list-driver  use driver white list
+    --include-flag FLAG  include only entries with a matching flag
+    --include-suspect    include only entries with an uppercase flag
+    --short-name         do not show the path portion of the node name
+    --show-lists         report of white and black lists
+    --version            Display program version and exit
+
+
+  Report driver source files that match the compatibles in the device
+  tree file and the kernel config options that enable the driver source
+  files.
+
+  This program must be run in the root directory of a Linux kernel
+  source tree.
+
+  The default format is a report that is intended to be easily human
+  scannable.
+
+  An alternate format can be selected by --config-format.  This will
+  create output that can easily be edited to create a fragment that can
+  be appended to the existing kernel config file.  Each entry consists of
+  multiple lines.  The first line reports flags, the node path, compatible
+  value, driver file matching the compatible, configuration options, and
+  current values of the configuration options.  For each configuration
+  option, the following lines report the current value and the value that
+  is required for the driver file to be included in the kernel.
+
+  If a large number of drivers or config options is listed for a node,
+  and the '$pr_flag_value[$pr_flag_pos_hard_coded]' flag is set consider using --white-list-config and/or
+  --white-list-driver.  If the white list option suppresses the correct
+  entry please report that as a bug.
+
+  CAUTION:
+     This program uses heuristics to guess which driver(s) support each
+     compatible string and which config option(s) enables the driver(s).
+     Do not believe that the reported information is fully correct.
+     This program is intended to aid the process of determining the
+     proper kernel configuration for a device tree, but this is not
+     a fully automated process -- human involvement may still be
+     required!
+
+     The driver match heuristic used is to search for source files
+     containing the compatible string enclosed in quotes.
+
+     This program might not be able to find all drivers matching a
+     compatible string.
+
+     Some makefiles are overly clever.  This program was not made
+     complex enough to handle them.  If no config option is listed
+     for a driver, look at the makefile for the driver source file.
+     Even if a config option is listed for a driver, some other
+     available config options may not be listed.
+
+  FLAG values:
+";
+
+       for ($k = 0; $k < $num_pr_flags; $k++) {
+               printf "     %s   %s\n", $pr_flag_value[$k], $pr_flag_help[$k];
+       }
+
+       print
+"
+     Upper case letters indicate potential issues or problems.
+
+  The flag:
+
+";
+
+       $k = $pr_flag_pos_hard_coded;
+       printf "     %s   %s\n", $pr_flag_value[$k], $pr_flag_help[$k];
+
+       print
+"
+  will be set if the config or driver is in the white lists, even if
+  --white-list-config and --white-list-driver are not specified.
+  This is a hint that 1) many of these reported lines are likely to
+  be incorrect, and 2) using those options will reduce the number of
+  drivers and/or config options reported.
+
+  --white-list-config and --white-list-driver may not be accurate if this
+  program is not well maintained.  Use them with appropriate skepticism.
+  Use the --show-lists option to report the values in the list.
+
+  Return value:
+    0   if no error
+    1   error processing command line
+    2   unable to open or read kernel config file
+    3   unable to open or process input device tree file(s)
+
+  EXAMPLES:
+
+     dt_to_config arch/arm/boot/dts/my_dts_file.dts
+
+       Basic report.
+
+     dt_to_config \\
+        --config \${KBUILD_OUTPUT}/.config \\
+        arch/\${ARCH}/boot/dts/my_dts_file.dts
+
+       Full report, with config file issues noted.
+
+     dt_to_config --include-suspect \\
+        --config \${KBUILD_OUTPUT}/.config \\
+        arch/\${ARCH}/boot/dts/my_dts_file.dts
+
+       Report of node / compatible string / driver tuples that should
+       be further investigated.  A node may have multiple compatible
+       strings.  A compatible string may be matched by multiple drivers.
+       A driver may have config file issues noted.  The compatible string
+       and/or driver may be in the white lists.
+
+     dt_to_config --include-suspect --config-format \\
+        --config ${KBUILD_OUTPUT}/.config \\
+        arch/\${ARCH}/boot/dts/my_dts_file.dts
+
+       Report of node / compatible string / driver tuples that should
+       be further investigated.  The report can be edited to uncomment
+       the config options to select the desired tuple for a given node.
+       A node may have multiple compatible strings.  A compatible string
+       may be matched by multiple drivers.  A driver may have config file
+       issues noted.  The compatible string and/or driver may be in the
+       white lists.
+
+";
+}
+
+sub set_flag()
+{
+       # pr_flags_ref is a reference to $pr_flags
+
+       my $pr_flags_ref = shift;
+       my $pos          = shift;
+
+       substr $$pr_flags_ref, $pos, 1, $pr_flag_value[$pos];
+
+       return $pr_flags;
+}
+
+sub print_flags()
+{
+       # return 1 if anything printed, else 0
+
+       # some fields of pn_arg_ref might not be used in this function, but
+       # extract all of them anyway.
+       my $pn_arg_ref     = shift;
+
+       my $compat         = $pn_arg_ref->{compat};
+       my $compatible_cnt = $pn_arg_ref->{compatible_cnt};
+       my $config         = $pn_arg_ref->{config};
+       my $config_cnt     = $pn_arg_ref->{config_cnt};
+       my $driver         = $pn_arg_ref->{driver};
+       my $driver_cnt     = $pn_arg_ref->{driver_cnt};
+       my $full_node      = $pn_arg_ref->{full_node};
+       my $node           = $pn_arg_ref->{node};
+       my $node_enabled   = $pn_arg_ref->{node_enabled};
+       my $white_list     = $pn_arg_ref->{white_list};
+
+       my $pr_flags       = '-' x $num_pr_flags;
+
+
+       # ----- set flags in $pr_flags
+
+       if ($compatible_cnt > 1) {
+               &set_flag(\$pr_flags, $pr_flag_pos_mcompatible);
+       }
+
+       if ($config_cnt > 1) {
+               &set_flag(\$pr_flags, $pr_flag_pos_mconfig);
+       }
+
+       if ($driver_cnt >= 1) {
+               &set_flag(\$pr_flags, $pr_flag_pos_driver);
+       }
+
+       if ($driver_cnt > 1) {
+               &set_flag(\$pr_flags, $pr_flag_pos_mdriver);
+       }
+
+       # These strings are the same way the linux kernel tests.
+       # The ePapr lists of values is slightly different.
+       if (!(
+             ($node_enabled eq "") ||
+             ($node_enabled eq "ok") ||
+             ($node_enabled eq "okay")
+            )) {
+               &set_flag(\$pr_flags, $pr_flag_pos_node_not_enabled);
+       }
+
+       if ($white_list) {
+               &set_flag(\$pr_flags, $pr_flag_pos_white_list);
+       }
+
+       if (exists($driver_hard_code_list{$compat}) ||
+           (exists($driver_config_hard_code_list{$driver}) &&
+            ($driver ne "no_driver"))) {
+               &set_flag(\$pr_flags, $pr_flag_pos_hard_coded);
+       }
+
+       my @configs = split(' && ', $config);
+       for $configs (@configs) {
+               $not = $configs =~ /^!/;
+               $configs =~ s/^!//;
+
+               if (($configs ne "no_config") && ($configs ne "no_makefile")) {
+                       &set_flag(\$pr_flags, $pr_flag_pos_config);
+               }
+
+               if (($config_cnt >= 1) &&
+                   ($configs !~ /CONFIG_/) &&
+                   (($configs ne "no_config") && ($configs ne "no_makefile"))) {
+                       &set_flag(\$pr_flags, $pr_flag_pos_config_hard_coded);
+               }
+
+               my $existing_config = $existing_config{$configs};
+               if ($existing_config eq "m") {
+                       &set_flag(\$pr_flags, $pr_flag_pos_config_m);
+                       # Possible fail, depends on whether built in or
+                       # module is desired.
+                       &set_flag(\$pr_flags, $pr_flag_pos_config_test_fail);
+               } elsif ($existing_config eq "y") {
+                       &set_flag(\$pr_flags, $pr_flag_pos_config_y);
+                       if ($not) {
+                               &set_flag(\$pr_flags, $pr_flag_pos_config_test_fail);
+                       }
+               } elsif (($config_file) && ($configs =~ /CONFIG_/)) {
+                       &set_flag(\$pr_flags, $pr_flag_pos_config_none);
+                       if (!$not) {
+                               &set_flag(\$pr_flags, $pr_flag_pos_config_test_fail);
+                       }
+               }
+       }
+
+       # ----- include / exclude filters
+
+       if ($include_flag_pattern && ($pr_flags !~ m/$include_flag_pattern/)) {
+               return 0;
+       }
+
+       if ($exclude_flag_pattern && ($pr_flags =~ m/$exclude_flag_pattern/)) {
+               return 0;
+       }
+
+       if ($config_format) {
+               print "# ";
+       }
+       print "$pr_flags : ";
+
+       return 1;
+}
+
+
+sub print_node()
+{
+       # return number of lines printed
+
+       # some fields of pn_arg_ref might not be used in this function, but
+       # extract all of them anyway.
+       my $pn_arg_ref     = shift;
+
+       my $compat         = $pn_arg_ref->{compat};
+       my $compatible_cnt = $pn_arg_ref->{compatible_cnt};
+       my $config         = $pn_arg_ref->{config};
+       my $config_cnt     = $pn_arg_ref->{config_cnt};
+       my $driver         = $pn_arg_ref->{driver};
+       my $driver_cnt     = $pn_arg_ref->{driver_cnt};
+       my $full_node      = $pn_arg_ref->{full_node};
+       my $node           = $pn_arg_ref->{node};
+       my $node_enabled   = $pn_arg_ref->{node_enabled};
+       my $white_list     = $pn_arg_ref->{white_list};
+
+       my $separator;
+
+       if (! &print_flags($pn_arg_ref)) {
+               return 0;
+       }
+
+
+       if ($short_name) {
+               print "$node";
+       } else {
+               print "$full_node";
+       }
+       print " : $compat : $driver : $config : ";
+
+       my @configs = split(' && ', $config);
+
+       if ($config_file) {
+               for $configs (@configs) {
+                       $configs =~ s/^!//;
+                       my $existing_config = $existing_config{$configs};
+                       if (!$existing_config) {
+                               # check for /-m/, /-y/, or /-objs/
+                               if ($configs !~ /CONFIG_/) {
+                                       $existing_config = "x";
+                               };
+                       };
+                       if ($existing_config) {
+                               print "$separator", "$existing_config";
+                               $separator = ", ";
+                       } else {
+                               print "$separator", "n";
+                               $separator = ", ";
+                       }
+               }
+       } else {
+               print "none";
+       }
+
+       print "\n";
+
+       if ($config_format) {
+               for $configs (@configs) {
+                       $not = $configs =~ /^!/;
+                       $configs =~ s/^!//;
+                       my $existing_config = $existing_config{$configs};
+
+                       if ($not) {
+                               if ($configs !~ /CONFIG_/) {
+                                       print "# $configs\n";
+                               } elsif ($existing_config eq "m") {
+                                       print "# $configs is m\n";
+                                       print "# $configs=n\n";
+                               } elsif ($existing_config eq "y") {
+                                       print "# $configs is set\n";
+                                       print "# $configs=n\n";
+                               } else {
+                                       print "# $configs is not set\n";
+                                       print "# $configs=n\n";
+                               }
+
+                       } else {
+                               if ($configs !~ /CONFIG_/) {
+                                       print "# $configs\n";
+                               } elsif ($existing_config eq "m") {
+                                       print "# $configs is m\n";
+                                       print "# $configs=y\n";
+                               } elsif ($existing_config eq "y") {
+                                       print "# $configs is set\n";
+                                       print "# $configs=y\n";
+                               } else {
+                                       print "# $configs is not set\n";
+                                       print "# $configs=y\n";
+                               }
+                       }
+               }
+       }
+
+       return 1;
+}
+
+
+sub scan_makefile
+{
+       my $pn_arg_ref    = shift;
+       my $driver        = shift;
+
+       # ----- Find Kconfig symbols that enable driver
+
+       my ($dir, $base) = $driver =~ m{(.*)/(.*).c};
+
+       my $makefile = $dir . "/Makefile";
+       if (! -r $makefile) {
+               $makefile = $dir . "/Kbuild";
+       }
+       if (! -r $makefile) {
+               my $config;
+
+               $config = 'no_makefile';
+               push @{ $driver_config{$driver} }, $config;
+               return;
+       }
+
+       if (!open(MAKEFILE_FILE, "<", "$makefile")) {
+               return;
+       }
+
+       my $line;
+       my @config;
+       my @if_config;
+       my @make_var;
+
+       NEXT_LINE:
+       while ($next_line = <MAKEFILE_FILE>) {
+               my $config;
+               my $if_config;
+               my $ifdef;
+               my $ifeq;
+               my $ifndef;
+               my $ifneq;
+               my $ifdef_config;
+               my $ifeq_config;
+               my $ifndef_config;
+               my $ifneq_config;
+
+               chomp($next_line);
+               $line = $line . $next_line;
+               if ($next_line =~ /\\$/) {
+                       $line =~ s/\\$/ /;
+                       next NEXT_LINE;
+               }
+               if ($line =~ /^\s*#/) {
+                       $line = "";
+                       next NEXT_LINE;
+               }
+
+               # -----  condition ... else ... endif
+
+               if ($line =~ /^([ ]\s*|)else\b/) {
+                       $if_config = "!" . pop @if_config;
+                       $if_config =~ s/^!!//;
+                       push @if_config, $if_config;
+                       $line =~ s/^([ ]\s*|)else\b//;
+               }
+
+               ($null, $ifeq_config,  $ifeq_config_val )  = $line =~ /^([ ]\s*|)ifeq\b.*\b(CONFIG_[A-Za-z0-9_]*)(.*)/;
+               ($null, $ifneq_config, $ifneq_config_val)  = $line =~ /^([ ]\s*|)ifneq\b.*\b(CONFIG_[A-Za-z0-9_]*)(.*)/;
+               ($null, $ifdef_config)                     = $line =~ /^([ ]\s*|)ifdef\b.*\b(CONFIG_[A-Za-z0-9_]*)/;
+               ($null, $ifndef_config)                    = $line =~ /^([ ]\s*|)ifndef\b.*\b(CONFIG_[A-Za-z0-9_]*)/;
+
+               ($null, $ifeq)   = $line =~ /^([ ]\s*|)ifeq\b\s*(.*)/;
+               ($null, $ifneq)  = $line =~ /^([ ]\s*|)ifneq\b\s*(.*)/;
+               ($null, $ifdef)  = $line =~ /^([ ]\s*|)ifdef\b\s*(.*)/;
+               ($null, $ifndef) = $line =~ /^([ ]\s*|)ifndef\b\s*(.*)/;
+
+               # Order of tests is important.  Prefer "CONFIG_*" regex match over
+               # less specific regex match.
+               if ($ifdef_config) {
+                       $if_config = $ifdef_config;
+               } elsif ($ifeq_config) {
+                       if ($ifeq_config_val =~ /y/) {
+                               $if_config = $ifeq_config;
+                       } else {
+                               $if_config = "!" . $ifeq_config;
+                       }
+               } elsif ($ifndef_config) {
+                       $if_config = "!" . $ifndef_config;
+               } elsif ($ifneq_config) {
+                       if ($ifneq_config_val =~ /y/) {
+                               $if_config = "!" . $ifneq_config;
+                       } else {
+                               $if_config = $ifneq_config;
+                       }
+               } elsif ($ifdef) {
+                       $if_config = $ifdef;
+               } elsif ($ifeq) {
+                       $if_config = $ifeq;
+               } elsif ($ifndef) {
+                       $if_config = "!" . $ifndef;
+               } elsif ($ifneq) {
+                       $if_config = "!" . $ifneq;
+               } else {
+                       $if_config = "";
+               }
+               $if_config =~ s/^!!//;
+
+               if ($if_config) {
+                       push @if_config, $if_config;
+                       $line = "";
+                       next NEXT_LINE;
+               }
+
+               if ($line =~ /^([ ]\s*|)endif\b/) {
+                       pop @if_config;
+                       $line = "";
+                       next NEXT_LINE;
+               }
+
+               # ----- simple CONFIG_* = *.[co]  or  xxx [+:?]*= *.[co]
+               # Most makefiles select on *.o, but
+               # arch/powerpc/boot/Makefile selects on *.c
+
+               ($config) = $line =~ /(CONFIG_[A-Za-z0-9_]+).*\b$base.[co]\b/;
+
+               # ----- match a make variable instead of *.[co]
+               # Recursively expanded variables are not handled.
+
+               if (!$config) {
+                       my $make_var;
+                       ($make_var) = $line =~ /\s*(\S+?)\s*[+:\?]*=.*\b$base.[co]\b/;
+                       if ($make_var) {
+                               if ($make_var =~ /[a-zA-Z0-9]+-[ym]/) {
+                                       $config = $make_var;
+                               } elsif ($make_var =~ /[a-zA-Z0-9]+-objs/) {
+                                       $config = $make_var;
+                               } else {
+                                       push @make_var, $make_var;
+                               }
+                       }
+               }
+
+               if (!$config) {
+                       for $make_var (@make_var) {
+                               ($config) = $line =~ /(CONFIG_[A-Za-z0-9_]+).*\b$make_var\b/;
+                               last if ($config);
+                       }
+               }
+
+               if (!$config) {
+                       for $make_var (@make_var) {
+                               ($config) = $line =~ /\s*(\S+?)\s*[+:\?]*=.*\b$make_var\b/;
+                               last if ($config);
+                       }
+               }
+
+               # ----- next if no config found
+
+               if (!$config) {
+                       $line = "";
+                       next NEXT_LINE;
+               }
+
+               for $if_config (@if_config) {
+                       $config = $if_config . " && " . $config;
+               }
+
+               push @{ $driver_config{$driver} }, $config;
+
+               $line = "";
+       }
+
+       close(MAKEFILE_FILE);
+
+}
+
+
+sub find_kconfig
+{
+       my $pn_arg_ref    = shift;
+       my $driver        = shift;
+
+       my $lines_printed = 0;
+       my @configs;
+
+       if (!@{ $driver_config{$driver} }) {
+               &scan_makefile($pn_arg_ref, $driver);
+               if (!@{ $driver_config{$driver} }) {
+                       push @{ $driver_config{$driver} }, "no_config";
+               }
+       }
+
+       @configs = @{ $driver_config{$driver} };
+
+       $$pn_arg_ref{config_cnt} = $#configs + 1;
+       for my $config (@configs) {
+               $$pn_arg_ref{config} = $config;
+               $lines_printed += &print_node($pn_arg_ref);
+       }
+
+       return $lines_printed;
+}
+
+
+sub handle_compatible()
+{
+       my $full_node     = shift;
+       my $node          = shift;
+       my $compatible    = shift;
+       my $node_enabled  = shift;
+
+       my $compat;
+       my $lines_printed = 0;
+       my %pn_arg        = ();
+
+       return if (!$node or !$compatible);
+
+       # Do not process compatible property of root node,
+       # it is used to match board, not to bind a driver.
+       return if ($node eq "/");
+
+       $pn_arg{full_node}    = $full_node;
+       $pn_arg{node}         = $node;
+       $pn_arg{node_enabled} = $node_enabled;
+
+       my @compatibles = split('", "', $compatible);
+
+       $compatibles[0] =~ s/^"//;
+       $compatibles[$#compatibles] =~ s/"$//;
+
+       $pn_arg{compatible_cnt} = $#compatibles + 1;
+
+       COMPAT:
+       for $compat (@compatibles) {
+
+               $pn_arg{compat}     = $compat;
+               $pn_arg{driver_cnt} = 0;
+               $pn_arg{white_list} = 0;
+
+               if (exists($compat_white_list{$compat})) {
+                       $pn_arg{white_list} = 1;
+                       $pn_arg{driver}     = "no_driver";
+                       $pn_arg{config_cnt} = 1;
+                       $pn_arg{config}     = "no_config";
+                       $lines_printed += &print_node(\%pn_arg);
+                       next COMPAT;
+               }
+
+               # ----- if compat previously seen, use cached info
+
+               if (exists($compat_driver{$compat})) {
+                       for my $driver (@{ $compat_driver{$compat} }) {
+                               $pn_arg{driver}     = $driver;
+                               $pn_arg{driver_cnt} = $driver_count{$compat};
+                               $pn_arg{config_cnt} = $#{ $driver_config{$driver}} + 1;
+
+                               for my $config (@{ $driver_config{$driver} }) {
+                                       $pn_arg{config} = $config;
+                                       $lines_printed += &print_node(\%pn_arg);
+                               }
+
+                               if (!@{ $driver_config{$driver} }) {
+                                       # no config cached yet
+                                       # $driver in %driver_hard_code_list
+                                       # but not %driver_config_hard_code_list
+                                       $lines_printed += &find_kconfig(\%pn_arg, $driver);
+                               }
+                       }
+                       next COMPAT;
+               }
+
+
+               # ----- Find drivers (source files that contain compatible)
+
+               # this will miss arch/sparc/include/asm/parport.h
+               # It is better to move the compatible out of the .h
+               # than to add *.h. to the files list, because *.h generates
+               # a lot of false negatives.
+               my $files = '"*.c"';
+               my $drivers = `git grep -l '"$compat"' -- $files`;
+               chomp($drivers);
+               if ($drivers eq "") {
+                       $pn_arg{driver} = "no_driver";
+                       $pn_arg{config_cnt} = 1;
+                       $pn_arg{config} = "no_config";
+                       push @{ $compat_driver{$compat} }, "no_driver";
+                       $lines_printed += &print_node(\%pn_arg);
+                       next COMPAT;
+               }
+
+               my @drivers = split("\n", $drivers);
+               $driver_count{$compat} = $#drivers + 1;
+               $pn_arg{driver_cnt}    = $#drivers + 1;
+
+               DRIVER:
+               for my $driver (@drivers) {
+                       push @{ $compat_driver{$compat} }, $driver;
+                       $pn_arg{driver} = $driver;
+
+                       # ----- if driver previously seen, use cached info
+
+                       $pn_arg{config_cnt} = $#{ $driver_config{$driver} } + 1;
+                       for my $config (@{ $driver_config{$driver} }) {
+                               $pn_arg{config} = $config;
+                               $lines_printed += &print_node(\%pn_arg);
+                       }
+                       if (@{ $driver_config{$driver} }) {
+                               next DRIVER;
+                       }
+
+                       if ($black_list_driver) {
+                               for $black (@black_list_driver) {
+                                       next DRIVER if ($driver =~ /^$black$/);
+                               }
+                       }
+
+
+                       # ----- Find Kconfig symbols that enable driver
+
+                       $lines_printed += &find_kconfig(\%pn_arg, $driver);
+
+               }
+       }
+
+       # White space (line) between nodes for readability.
+       # Each node may report several compatibles.
+       # For each compatible, multiple drivers may be reported.
+       # For each driver, multiple CONFIG_ options may be reported.
+       if ($lines_printed) {
+               print "\n";
+       }
+}
+
+sub read_dts()
+{
+       my $file         = shift;
+
+       my $compatible   = "";
+       my $line;
+       my $node         = "";
+       my $node_enabled = "";
+
+       if (! -r $file) {
+               print STDERR "file '$file' is not readable or does not exist\n";
+               exit 3;
+       }
+
+       if (!open(DT_FILE, "-|", "$dtx_diff $file")) {
+               print STDERR "\n";
+               print STDERR "shell command failed:\n";
+               print STDERR "   $dtx_diff $file\n";
+               print STDERR "\n";
+               exit 3;
+       }
+
+       FILE:
+       while ($line = <DT_FILE>) {
+               chomp($line);
+
+               if ($line =~ /{/) {
+
+                       &handle_compatible($full_node, $node, $compatible,
+                                          $node_enabled);
+
+                       while ($end_node_count-- > 0) {
+                               pop @full_node;
+                       };
+                       $end_node_count = 0;
+                       $full_node = @full_node[-1];
+
+                       $node = $line;
+                       $node =~ s/^\s*(.*)\s+\{.*/$1/;
+                       $node =~ s/.*: //;
+                       if ($node eq '/' ) {
+                               $full_node = '/';
+                       } elsif ($full_node ne '/') {
+                               $full_node = $full_node . '/' . $node;
+                       } else {
+                               $full_node = '/' . $node;
+                       }
+                       push @full_node, $full_node;
+
+                       $compatible = "";
+                       $node_enabled = "";
+                       next FILE;
+               }
+
+               if ($line =~ /}/) {
+                       $end_node_count++;
+               }
+
+               if ($line =~ /(\s+|^)status =/) {
+                       $node_enabled = $line;
+                       $node_enabled =~ s/^\t*//;
+                       $node_enabled =~ s/^status = "//;
+                       $node_enabled =~ s/";$//;
+                       next FILE;
+               }
+
+               if ($line =~ /(\s+|^)compatible =/) {
+                       # Extract all compatible entries for this device
+                       # White space matching here and in handle_compatible() is
+                       # precise, because input format is the output of dtc,
+                       # which is invoked by dtx_diff.
+                       $compatible = $line;
+                       $compatible =~ s/^\t*//;
+                       $compatible =~ s/^compatible = //;
+                       $compatible =~ s/;$//;
+               }
+       }
+
+       &handle_compatible($full_node, $node, $compatible, $node_enabled);
+
+       close(DT_FILE);
+}
+
+
+sub read_config_file()
+{
+       if (! -r $config_file) {
+               print STDERR "file '$config_file' is not readable or does not exist\n";
+               exit 2;
+       }
+
+       if (!open(CONFIG_FILE, "<", "$config_file")) {
+               print STDERR "open $config_file failed\n";
+               exit 2;
+       }
+
+       my @line;
+
+       LINE:
+       while ($line = <CONFIG_FILE>) {
+               chomp($line);
+               next LINE if ($line =~ /^\s*#/);
+               next LINE if ($line =~ /^\s*$/);
+               @line = split /=/, $line;
+               $existing_config{@line[0]} = @line[1];
+       }
+
+       close(CONFIG_FILE);
+}
+
+
+sub cmd_line_err()
+{
+       my $msg = shift;
+
+       print STDERR "\n";
+       print STDERR "   ERROR processing command line options\n";
+       print STDERR "         $msg\n" if ($msg ne "");
+       print STDERR "\n";
+       print STDERR "   For help, type '$script_name --help'\n";
+       print STDERR "\n";
+}
+
+
+# -----------------------------------------------------------------------------
+# program entry point
+
+Getopt::Long::Configure("no_ignore_case", "bundling");
+
+if (!GetOptions(
+       "c=s"               => \$config_file,
+       "config=s"          => \$config_file,
+       "config-format"     => \$config_format,
+       "exclude-flag=s"    => \@exclude_flag,
+       "h"                 => \$help,
+       "help"              => \$help,
+       "black-list-driver" => \$black_list_driver,
+       "white-list-config" => \$white_list_config,
+       "white-list-driver" => \$white_list_driver,
+       "include-flag=s"    => \@include_flag,
+       "include-suspect"   => \$include_suspect,
+       "short-name"        => \$short_name,
+       "show-lists"        => \$show_lists,
+       "version"           => \$version,
+       )) {
+
+       &cmd_line_err();
+
+       exit 1;
+}
+
+
+my $exit_after_messages = 0;
+
+if ($version) {
+       print STDERR "\n$script_name  $VUFX\n\n";
+       $exit_after_messages = 1;
+}
+
+
+if ($help) {
+       &usage;
+       $exit_after_messages = 1;
+}
+
+
+if ($show_lists) {
+
+       print "\n";
+       print "These compatibles are hard coded to have no driver.\n";
+       print "\n";
+       for my $compat (sort keys %compat_white_list) {
+               print "   $compat\n";
+       }
+
+
+       print "\n\n";
+       print "The driver for these compatibles is hard coded (white list).\n";
+       print "\n";
+       my $max_compat_len = 0;
+       for my $compat (sort keys %driver_hard_code_list) {
+               if (length $compat > $max_compat_len) {
+                       $max_compat_len = length $compat;
+               }
+       }
+       for my $compat (sort keys %driver_hard_code_list) {
+               if (($driver ne "hardcoded_no_driver") && ($driver ne "no_driver")) {
+                       my $first = 1;
+                       for my $driver (@{ $driver_hard_code_list{$compat} }) {
+                               if ($first) {
+                                       print "   $compat";
+                                       print " " x ($max_compat_len - length $compat);
+                                       $first = 0;
+                               } else {
+                                       print "   ", " " x $max_compat_len;
+                               }
+                               print "  $driver\n";
+                       }
+               }
+       }
+
+
+       print "\n\n";
+       print "The configuration option for these drivers is hard coded (white list).\n";
+       print "\n";
+       my $max_driver_len = 0;
+       for my $driver (sort keys %driver_config_hard_code_list) {
+               if (length $driver > $max_driver_len) {
+                       $max_driver_len = length $driver;
+               }
+       }
+       for my $driver (sort keys %driver_config_hard_code_list) {
+               if (($driver ne "hardcoded_no_driver") && ($driver ne "no_driver")) {
+                       my $first = 1;
+                       for my $config (@{ $driver_config_hard_code_list{$driver} }) {
+                               if ($first) {
+                                       print "   $driver";
+                                       print " " x ($max_driver_len - length $driver);
+                                       $first = 0;
+                               } else {
+                                       print "   ", " " x $max_driver_len;
+                               }
+                               print "  $config\n";
+                       }
+               }
+       }
+
+
+       print "\n\n";
+       print "These drivers are black listed.\n";
+       print "\n";
+       for my $driver (@black_list_driver) {
+               print "   $driver\n";
+       }
+
+       print "\n";
+
+       $exit_after_messages = 1;
+}
+
+
+if ($exit_after_messages) {
+       exit 0;
+}
+
+
+$exclude_flag_pattern = "[";
+for my $exclude_flag (@exclude_flag) {
+       $exclude_flag_pattern = $exclude_flag_pattern . $exclude_flag;
+}
+$exclude_flag_pattern = $exclude_flag_pattern . "]";
+# clean up if empty
+$exclude_flag_pattern =~ s/^\[\]$//;
+
+
+$include_flag_pattern = "[";
+for my $include_flag (@include_flag) {
+       $include_flag_pattern = $include_flag_pattern . $include_flag;
+}
+$include_flag_pattern = $include_flag_pattern . "]";
+# clean up if empty
+$include_flag_pattern =~ s/^\[\]$//;
+
+
+if ($exclude_flag_pattern) {
+       my $found = 0;
+       for $pr_flag_value (@pr_flag_value) {
+               if ($exclude_flag_pattern =~ m/$pr_flag_value/) {
+                       $found = 1;
+               }
+       }
+       if (!$found) {
+               &cmd_line_err("invalid value for FLAG in --exclude-flag\n");
+               exit 1
+       }
+}
+
+if ($include_flag_pattern) {
+       my $found = 0;
+       for $pr_flag_value (@pr_flag_value) {
+               if ($include_flag_pattern =~ m/$pr_flag_value/) {
+                       $found = 1;
+               }
+       }
+       if (!$found) {
+               &cmd_line_err("invalid value for FLAG in --include-flag\n");
+               exit 1
+       }
+}
+
+if ($include_suspect) {
+       $include_flag_pattern =~ s/\[//;
+       $include_flag_pattern =~ s/\]//;
+       $include_flag_pattern = "[" . $include_flag_pattern . "A-Z]";
+}
+
+if ($exclude_flag_pattern =~ m/$include_flag_pattern/) {
+       &cmd_line_err("the same flag appears in both --exclude-flag and --include-flag or --include-suspect\n");
+       exit 1
+}
+
+
+# ($#ARGV < 0) is valid for --help, --version
+if ($#ARGV < 0) {
+       &cmd_line_err("device-tree... is required");
+       exit 1
+}
+
+
+if ($config_file) {
+       &read_config_file();
+}
+
+
+# avoid pushing duplicates for this value
+$driver = "hardcoded_no_driver";
+for $config ( @{ $driver_config_hard_code_list{$driver} } ) {
+       push @{ $driver_config{$driver} }, $config;
+}
+
+if ($white_list_driver) {
+       for my $compat (keys %driver_hard_code_list) {
+               for my $driver (@{ $driver_hard_code_list{$compat} }) {
+                       push @{ $compat_driver{$compat} }, $driver;
+                       if ($driver ne "hardcoded_no_driver") {
+                               $driver_count{$compat} = scalar @{ $compat_driver{$compat} };
+                       }
+               }
+       }
+}
+
+if ($white_list_config) {
+       for my $driver (keys %driver_config_hard_code_list) {
+               if ($driver ne "hardcoded_no_driver") {
+                       for $config ( @{ $driver_config_hard_code_list{$driver} } ) {
+                               push @{ $driver_config{$driver} }, $config;
+                       }
+               }
+       }
+}
+
+if (-x "scripts/dtc/dtx_diff") {
+       $dtx_diff = "scripts/dtc/dtx_diff";
+} else {
+
+       print STDERR "\n";
+       print STDERR "$script_name must be run from the root directory of a Linux kernel tree\n";
+       print STDERR "\n";
+       exit 3;
+}
+
+for $file (@ARGV) {
+       &read_dts($file);
+}
diff --git a/scripts/dtc/dtx_diff b/scripts/dtc/dtx_diff
index 959ab2646d38..ec47f95991a3 100755
--- a/scripts/dtc/dtx_diff
+++ b/scripts/dtc/dtx_diff
@@ -266,7 +266,7 @@ DTC="${__KBUILD_OUTPUT}/scripts/dtc/dtc"
 
 if [ ! -x ${DTC} ] ; then
 	__DTC="dtc"
-	if grep -q "^CONFIG_DTC=y" ${__KBUILD_OUTPUT}/.config ; then
+	if grep -q "^CONFIG_DTC=y" ${__KBUILD_OUTPUT}/.config 2>/dev/null; then
 		make_command='
          make scripts'
 	else