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1 #!/usr/bin/python | |
2 | |
3 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved. | |
4 # Use of this source code is governed by a BSD-style license that can be | |
5 # found in the LICENSE file. | |
6 | |
7 """A script to manipulate ChromeOS CMOS reboot Field. | |
8 | |
9 A few bits in a byte in CMOS (called RDB, short for 'Reboot Data Byte' | |
10 hereafter) are dedicated to information exchange between Linux and BIOS. | |
11 | |
12 The CMOS contents are available through /dev/nvrom. The location of RDB is | |
13 reported by BIOS through ACPI. The few bits in RDB operated on by this script | |
14 are defined in the all_mode_fields dictionary below along with their | |
15 functions. | |
16 | |
17 When invoked without parameters this script prints values of the fields. When | |
18 invoked with any of the bit field names as parameter(s), the script sets the | |
19 bit(s) as required. | |
20 | |
21 Additional parameters allow to specify alternative ACPI and NVRAM files for | |
22 testing. | |
23 """ | |
24 | |
25 __author__ = 'The Chromium OS Authors' | |
26 | |
27 import optparse | |
28 import sys | |
29 | |
30 class RebootModeError(Exception): | |
31 pass | |
32 | |
33 # global variables | |
34 parser = optparse.OptionParser() | |
35 acpi_file = '/sys/devices/platform/chromeos_acpi/CHNV' | |
36 nvram_file = '/dev/nvram' | |
37 | |
38 # Offset of RDB in NVRAM | |
39 rdb_offset = 0 | |
40 | |
41 # NVRAM contents read on startup | |
42 rdb_value = '' | |
43 | |
44 # All bitfields in RDB this script provides access to. Field names prepended | |
45 # by `--' become this script's command line options | |
46 all_mode_fields = { | |
47 'recovery' : 0x80, | |
48 'debug_reset' : 0x40, | |
49 'try_firmware_b': 0x20 | |
50 } | |
51 | |
52 # A dictionary of fields to be updated as requested by the command line | |
53 # parameters | |
54 fields_to_set = {} | |
55 | |
56 | |
57 def OptionHandler(option, opt_str, value, p): | |
58 """Process bit field name command line parameter. | |
59 | |
60 Verifies that the value is in range (0 or 1) and adds the appropriate | |
61 element to fields_to_set dictionary. Should the same field specified in the | |
62 command line more than once, only the last value will be used. | |
63 | |
64 Raises: | |
65 RebootModeError in case the parameter value is out of range. | |
66 """ | |
67 | |
68 global fields_to_set | |
69 key = opt_str[2:] | |
70 if value < 0 or value > 1: | |
71 raise RebootModeError('--%s should be either 0 or 1' % key) | |
72 | |
73 fields_to_set[key] = value | |
74 | |
75 | |
76 def PrepareOptions(): | |
77 global parser | |
78 for field in all_mode_fields: | |
79 parser.add_option('--' + field, action='callback', type='int', | |
80 callback=OptionHandler) | |
81 parser.add_option('--acpi_file', dest='acpi_file') | |
82 parser.add_option('--nvram_file', dest='nvram_file') | |
83 | |
84 | |
85 def ParseOptions(): | |
86 global acpi_file | |
87 global nvram_file | |
88 (opts, args) = parser.parse_args() | |
89 | |
90 if opts.acpi_file is not None: | |
91 acpi_file = opts.acpi_file | |
92 | |
93 if opts.nvram_file is not None: | |
94 nvram_file = opts.nvram_file | |
95 | |
96 | |
97 def GetRDBOffset(): | |
98 global rdb_offset | |
99 try: | |
100 f = open(acpi_file, 'r') | |
101 rdb_offset = int(f.read()) | |
102 f.close() | |
103 except IOError, e: | |
104 raise RebootModeError('Trying to read %s got this: %s' % (acpi_file, e)) | |
105 except ValueError: | |
106 raise RebootModeError('%s contents are corrupted' % acpi_file) | |
107 | |
108 | |
109 def ReadNvram(): | |
110 global rdb_value | |
111 try: | |
112 f = open(nvram_file, 'rb') | |
113 f.seek(rdb_offset) | |
114 rdb_value = ord(f.read(1)[0]) | |
115 f.close() | |
116 except IOError, e: | |
117 if e[0] == 2: | |
118 raise RebootModeError( | |
119 '%s does not exist. Is nvram module installed?' % nvram_file) | |
120 if e[0] == 13: | |
121 raise RebootModeError('Access to %s denied. Are you root?' % nvram_file) | |
122 raise RebootModeError(e[1]) | |
123 except IndexError, e: | |
124 raise RebootModeError('Failed reading mode byte from %s' % nvram_file) | |
125 | |
126 | |
127 def PrintCurrentMode(): | |
128 print 'Current reboot mode settings:' | |
129 for (field, mask) in all_mode_fields.iteritems(): | |
130 print '%-15s: %d' % (field, int(not not (rdb_value & mask))) | |
131 | |
132 | |
133 def SetNewMode(): | |
134 new_mode = 0 | |
135 updated_bits_mask = 0 | |
136 | |
137 for (opt, value) in fields_to_set.iteritems(): | |
138 mask = all_mode_fields[opt] | |
139 if value: | |
140 new_mode |= mask | |
141 updated_bits_mask |= mask | |
142 | |
143 if (rdb_value & updated_bits_mask) == new_mode: | |
144 print 'No update required' | |
145 return | |
146 | |
147 f = open(nvram_file, 'rb+') | |
148 f.seek(rdb_offset) | |
149 new_mode |= (rdb_value & ~updated_bits_mask) | |
150 f.write('%c' % new_mode) | |
151 f.close() | |
152 | |
153 | |
154 def DoRebootMode(): | |
155 PrepareOptions() | |
156 ParseOptions() | |
157 GetRDBOffset() | |
158 ReadNvram() | |
159 if fields_to_set: | |
160 SetNewMode() | |
161 else: | |
162 PrintCurrentMode() | |
163 | |
164 | |
165 if __name__ == '__main__': | |
166 try: | |
167 DoRebootMode() | |
168 except RebootModeError, e: | |
169 print >> sys.stderr, '%s: %s' % (sys.argv[0].split('/')[-1], e) | |
170 sys.exit(1) | |
171 sys.exit(0) | |
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