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 entry import Entry 9from blob import Entry_blob 10import tools 11 12class Entry_u_boot_ucode(Entry_blob): 13 """U-Boot microcode block 14 15 U-Boot on x86 needs a single block of microcode. This is collected from 16 the various microcode update nodes in the device tree. It is also unable 17 to read the microcode from the device tree on platforms that use FSP 18 (Firmware Support Package) binaries, because the API requires that the 19 microcode is supplied before there is any SRAM available to use (i.e. 20 the FSP sets up the SRAM / cache-as-RAM but does so in the call that 21 requires the microcode!). To keep things simple, all x86 platforms handle 22 microcode the same way in U-Boot (even non-FSP platforms). This is that 23 a table is placed at _dt_ucode_base_size containing the base address and 24 size of the microcode. This is either passed to the FSP (for FSP 25 platforms), or used to set up the microcode (for non-FSP platforms). 26 This all happens in the build system since it is the only way to get 27 the microcode into a single blob and accessible without SRAM. 28 29 There are two cases to handle. If there is only one microcode blob in 30 the device tree, then the ucode pointer it set to point to that. This 31 entry (u-boot-ucode) is empty. If there is more than one update, then 32 this entry holds the concatenation of all updates, and the device tree 33 entry (u-boot-dtb-with-ucode) is updated to remove the microcode. This 34 last step ensures that that the microcode appears in one contiguous 35 block in the image and is not unnecessarily duplicated in the device 36 tree. It is referred to as 'collation' here. 37 38 Entry types that have a part to play in handling microcode: 39 40 Entry_u_boot_with_ucode_ptr: 41 Contains u-boot-nodtb.bin (i.e. U-Boot without the device tree). 42 It updates it with the address and size of the microcode so that 43 U-Boot can find it early on start-up. 44 Entry_u_boot_dtb_with_ucode: 45 Contains u-boot.dtb. It stores the microcode in a 46 'self.ucode_data' property, which is then read by this class to 47 obtain the microcode if needed. If collation is performed, it 48 removes the microcode from the device tree. 49 Entry_u_boot_ucode: 50 This class. If collation is enabled it reads the microcode from 51 the Entry_u_boot_dtb_with_ucode entry, and uses it as the 52 contents of this entry. 53 """ 54 def __init__(self, section, etype, node): 55 Entry_blob.__init__(self, section, etype, node) 56 57 def ObtainContents(self): 58 # If the section does not need microcode, there is nothing to do 59 ucode_dest_entry = self.section.FindEntryType('u-boot-with-ucode-ptr') 60 ucode_dest_entry_spl = self.section.FindEntryType( 61 'u-boot-spl-with-ucode-ptr') 62 if ((not ucode_dest_entry or not ucode_dest_entry.target_pos) and 63 (not ucode_dest_entry_spl or not ucode_dest_entry_spl.target_pos)): 64 self.data = '' 65 return True 66 67 # Get the microcode from the device tree entry 68 fdt_entry = self.section.FindEntryType('u-boot-dtb-with-ucode') 69 if not fdt_entry or not fdt_entry.ucode_data: 70 return False 71 72 if not fdt_entry.collate: 73 # This binary can be empty 74 self.data = '' 75 return True 76 77 # Write it out to a file 78 dtb_name = 'u-boot-ucode.bin' 79 fname = tools.GetOutputFilename(dtb_name) 80 with open(fname, 'wb') as fd: 81 fd.write(fdt_entry.ucode_data) 82 83 self._pathname = fname 84 self.ReadContents() 85 86 return True 87