1# SPDX-License-Identifier: GPL-2.0+
2# Copyright (c) 2016 Google, Inc
3# Written by Simon Glass <sjg@chromium.org>
4#
5# Entry-type module for a U-Boot binary with an embedded microcode pointer
6#
7
8from binman.entry import Entry
9from binman.etype.blob import Entry_blob
10from u_boot_pylib import tools
11
12class Entry_u_boot_ucode(Entry_blob):
13    """U-Boot microcode block
14
15    Properties / Entry arguments:
16        None
17
18    The contents of this entry are filled in automatically by other entries
19    which must also be in the image.
20
21    U-Boot on x86 needs a single block of microcode. This is collected from
22    the various microcode update nodes in the device tree. It is also unable
23    to read the microcode from the device tree on platforms that use FSP
24    (Firmware Support Package) binaries, because the API requires that the
25    microcode is supplied before there is any SRAM available to use (i.e.
26    the FSP sets up the SRAM / cache-as-RAM but does so in the call that
27    requires the microcode!). To keep things simple, all x86 platforms handle
28    microcode the same way in U-Boot (even non-FSP platforms). This is that
29    a table is placed at _dt_ucode_base_size containing the base address and
30    size of the microcode. This is either passed to the FSP (for FSP
31    platforms), or used to set up the microcode (for non-FSP platforms).
32    This all happens in the build system since it is the only way to get
33    the microcode into a single blob and accessible without SRAM.
34
35    There are two cases to handle. If there is only one microcode blob in
36    the device tree, then the ucode pointer it set to point to that. This
37    entry (u-boot-ucode) is empty. If there is more than one update, then
38    this entry holds the concatenation of all updates, and the device tree
39    entry (u-boot-dtb-with-ucode) is updated to remove the microcode. This
40    last step ensures that that the microcode appears in one contiguous
41    block in the image and is not unnecessarily duplicated in the device
42    tree. It is referred to as 'collation' here.
43
44    Entry types that have a part to play in handling microcode:
45
46        Entry_u_boot_with_ucode_ptr:
47            Contains u-boot-nodtb.bin (i.e. U-Boot without the device tree).
48            It updates it with the address and size of the microcode so that
49            U-Boot can find it early on start-up.
50        Entry_u_boot_dtb_with_ucode:
51            Contains u-boot.dtb. It stores the microcode in a
52            'self.ucode_data' property, which is then read by this class to
53            obtain the microcode if needed. If collation is performed, it
54            removes the microcode from the device tree.
55        Entry_u_boot_ucode:
56            This class. If collation is enabled it reads the microcode from
57            the Entry_u_boot_dtb_with_ucode entry, and uses it as the
58            contents of this entry.
59    """
60    def __init__(self, section, etype, node):
61        super().__init__(section, etype, node)
62
63    def ObtainContents(self):
64        # If the section does not need microcode, there is nothing to do
65        found = False
66        for suffix in ['', '-spl', '-tpl']:
67            name = 'u-boot%s-with-ucode-ptr' % suffix
68            entry = self.section.FindEntryType(name)
69            if entry and entry.target_offset:
70                found = True
71        if not found:
72            self.data = b''
73            return True
74        # Get the microcode from the device tree entry. If it is not available
75        # yet, return False so we will be called later. If the section simply
76        # doesn't exist, then we may as well return True, since we are going to
77        # get an error anyway.
78        for suffix in ['', '-spl', '-tpl']:
79            name = 'u-boot%s-dtb-with-ucode' % suffix
80            fdt_entry = self.section.FindEntryType(name)
81            if fdt_entry:
82                break
83        if not fdt_entry:
84            self.data = b''
85            return True
86        if not fdt_entry.ready:
87            return False
88
89        if not fdt_entry.collate:
90            # This binary can be empty
91            self.data = b''
92            return True
93
94        # Write it out to a file
95        self._pathname = tools.get_output_filename('u-boot-ucode.bin')
96        tools.write_file(self._pathname, fdt_entry.ucode_data)
97
98        self.ReadBlobContents()
99
100        return True
101