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6b6024eadb
There are two enable methods supported by ARM64 Linux; psci and
spin-table. The latter is simpler and helpful for quick SoC bring
up. My main motivation for this patch is to improve the spin-table
support, which allows us to boot an ARMv8 system without the ARM
Trusted Firmware.
Currently, we have multi-entry code in arch/arm/cpu/armv8/start.S
and the spin-table is supported in a really ad-hoc way, and I see
some problems:
- We must hard-code CPU_RELEASE_ADDR so that it matches the
"cpu-release-addr" property in the DT that comes from the
kernel tree.
- The Documentation/arm64/booting.txt in Linux requires that
the release address must be zero-initialized, but it is not
cared by the common code in U-Boot. We must do it in a board
function.
- There is no systematic way to protect the spin-table code from
the kernel. We are supposed to do it in a board specific manner,
but it is difficult to predict where the spin-table code will be
located after the relocation. So, it also makes difficult to
hard-code /memreserve/ in the DT of the kernel.
So, here is a patch to solve those problems; the DT is run-time
modified to reserve the spin-table code (+ cpu-release-addr).
Also, the "cpu-release-addr" property is set to an appropriate
address after the relocation, which means we no longer need the
hard-coded CPU_RELEASE_ADDR.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
64 lines
1.6 KiB
C
64 lines
1.6 KiB
C
/*
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* Copyright (C) 2016 Socionext Inc.
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* Author: Masahiro Yamada <yamada.masahiro@socionext.com>
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#include <common.h>
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#include <libfdt.h>
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#include <asm/spin_table.h>
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int spin_table_update_dt(void *fdt)
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{
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int cpus_offset, offset;
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const char *prop;
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int ret;
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unsigned long rsv_addr = (unsigned long)&spin_table_reserve_begin;
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unsigned long rsv_size = &spin_table_reserve_end -
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&spin_table_reserve_begin;
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cpus_offset = fdt_path_offset(fdt, "/cpus");
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if (cpus_offset < 0)
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return -ENODEV;
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for (offset = fdt_first_subnode(fdt, cpus_offset);
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offset >= 0;
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offset = fdt_next_subnode(fdt, offset)) {
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prop = fdt_getprop(fdt, offset, "device_type", NULL);
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if (!prop || strcmp(prop, "cpu"))
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continue;
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/*
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* In the first loop, we check if every CPU node specifies
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* spin-table. Otherwise, just return successfully to not
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* disturb other methods, like psci.
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*/
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prop = fdt_getprop(fdt, offset, "enable-method", NULL);
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if (!prop || strcmp(prop, "spin-table"))
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return 0;
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}
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for (offset = fdt_first_subnode(fdt, cpus_offset);
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offset >= 0;
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offset = fdt_next_subnode(fdt, offset)) {
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prop = fdt_getprop(fdt, offset, "device_type", NULL);
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if (!prop || strcmp(prop, "cpu"))
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continue;
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ret = fdt_setprop_u64(fdt, offset, "cpu-release-addr",
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(unsigned long)&spin_table_cpu_release_addr);
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if (ret)
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return -ENOSPC;
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}
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ret = fdt_add_mem_rsv(fdt, rsv_addr, rsv_size);
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if (ret)
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return -ENOSPC;
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printf(" Reserved memory region for spin-table: addr=%lx size=%lx\n",
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rsv_addr, rsv_size);
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return 0;
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}
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