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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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335b139057
Add a mechanism for early SoC initialization for platforms that need
additional hardware initialization not possible through the regular
device tree and drivers mechanism. With this, a SoC specific
initialization function can be called very early, before DTB parsing
is done by parse_dtb() in Linux RISC-V kernel setup code.
This can be very useful for early hardware initialization for No-MMU
kernels booted directly in M-mode because it is quite likely that no
other booting stage exist prior to the No-MMU kernel.
Example use of a SoC early initialization is as follows:
static void vendor_abc_early_init(const void *fdt)
{
/*
* some early init code here that can use simple matches
* against the flat device tree file.
*/
}
SOC_EARLY_INIT_DECLARE("vendor,abc", abc_early_init);
This early initialization function is executed only if the flat device
tree for the board has a 'compatible = "vendor,abc"' entry;
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
29 lines
735 B
C
29 lines
735 B
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2020 Western Digital Corporation or its affiliates.
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*/
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#include <linux/init.h>
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#include <linux/libfdt.h>
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#include <asm/pgtable.h>
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#include <asm/soc.h>
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/*
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* This is called extremly early, before parse_dtb(), to allow initializing
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* SoC hardware before memory or any device driver initialization.
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*/
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void __init soc_early_init(void)
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{
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void (*early_fn)(const void *fdt);
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const struct of_device_id *s;
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const void *fdt = dtb_early_va;
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for (s = (void *)&__soc_early_init_table_start;
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(void *)s < (void *)&__soc_early_init_table_end; s++) {
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if (!fdt_node_check_compatible(fdt, 0, s->compatible)) {
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early_fn = s->data;
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early_fn(fdt);
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return;
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}
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}
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}
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