u-boot/arch/arm/cpu/armv8/spin_table.c
Masahiro Yamada 6b6024eadb arm64: add better and more generic spin-table support
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>
2016-07-14 18:22:16 -04:00

63 lines
1.6 KiB
C

/*
* Copyright (C) 2016 Socionext Inc.
* Author: Masahiro Yamada <yamada.masahiro@socionext.com>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <libfdt.h>
#include <asm/spin_table.h>
int spin_table_update_dt(void *fdt)
{
int cpus_offset, offset;
const char *prop;
int ret;
unsigned long rsv_addr = (unsigned long)&spin_table_reserve_begin;
unsigned long rsv_size = &spin_table_reserve_end -
&spin_table_reserve_begin;
cpus_offset = fdt_path_offset(fdt, "/cpus");
if (cpus_offset < 0)
return -ENODEV;
for (offset = fdt_first_subnode(fdt, cpus_offset);
offset >= 0;
offset = fdt_next_subnode(fdt, offset)) {
prop = fdt_getprop(fdt, offset, "device_type", NULL);
if (!prop || strcmp(prop, "cpu"))
continue;
/*
* In the first loop, we check if every CPU node specifies
* spin-table. Otherwise, just return successfully to not
* disturb other methods, like psci.
*/
prop = fdt_getprop(fdt, offset, "enable-method", NULL);
if (!prop || strcmp(prop, "spin-table"))
return 0;
}
for (offset = fdt_first_subnode(fdt, cpus_offset);
offset >= 0;
offset = fdt_next_subnode(fdt, offset)) {
prop = fdt_getprop(fdt, offset, "device_type", NULL);
if (!prop || strcmp(prop, "cpu"))
continue;
ret = fdt_setprop_u64(fdt, offset, "cpu-release-addr",
(unsigned long)&spin_table_cpu_release_addr);
if (ret)
return -ENOSPC;
}
ret = fdt_add_mem_rsv(fdt, rsv_addr, rsv_size);
if (ret)
return -ENOSPC;
printf(" Reserved memory region for spin-table: addr=%lx size=%lx\n",
rsv_addr, rsv_size);
return 0;
}