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[acpi] Expose ACPI tables via settings mechanism
Allow values to be read from ACPI tables using the syntax ${acpi/<signature>.<index>.0.<offset>.<length>} where <signature> is the ACPI table signature as a 32-bit hexadecimal number (e.g. 0x41504093 for the 'APIC' signature on the MADT), <index> is the index into the array of tables matching this signature, <offset> is the byte offset within the table, and <length> is the field length in bytes. Numeric values are returned in reverse byte order, since ACPI numeric values are usually little-endian. For example: ${acpi/0x41504943.0.0.0.0} - entire MADT table in raw hex ${acpi/0x41504943.0.0.0x0a.6:string} - MADT table OEM ID ${acpi/0x41504943.0.0.0x24.4:uint32} - local APIC address Signed-off-by: Michael Brown <mcb30@ipxe.org>
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/* | ||
* Copyright (C) 2017 Michael Brown <mbrown@fensystems.co.uk>. | ||
* | ||
* This program is free software; you can redistribute it and/or | ||
* modify it under the terms of the GNU General Public License as | ||
* published by the Free Software Foundation; either version 2 of the | ||
* License, or any later version. | ||
* | ||
* This program is distributed in the hope that it will be useful, but | ||
* WITHOUT ANY WARRANTY; without even the implied warranty of | ||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
* General Public License for more details. | ||
* | ||
* You should have received a copy of the GNU General Public License | ||
* along with this program; if not, write to the Free Software | ||
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA | ||
* 02110-1301, USA. | ||
* | ||
* You can also choose to distribute this program under the terms of | ||
* the Unmodified Binary Distribution Licence (as given in the file | ||
* COPYING.UBDL), provided that you have satisfied its requirements. | ||
*/ | ||
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ); | ||
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/** | ||
* @file | ||
* | ||
* ACPI settings | ||
* | ||
*/ | ||
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#include <string.h> | ||
#include <errno.h> | ||
#include <ipxe/init.h> | ||
#include <ipxe/settings.h> | ||
#include <ipxe/acpi.h> | ||
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/** ACPI settings scope */ | ||
static const struct settings_scope acpi_settings_scope; | ||
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/** | ||
* Check applicability of ACPI setting | ||
* | ||
* @v settings Settings block | ||
* @v setting Setting | ||
* @ret applies Setting applies within this settings block | ||
*/ | ||
static int acpi_settings_applies ( struct settings *settings __unused, | ||
const struct setting *setting ) { | ||
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return ( setting->scope == &acpi_settings_scope ); | ||
} | ||
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/** | ||
* Fetch value of ACPI setting | ||
* | ||
* @v settings Settings block | ||
* @v setting Setting to fetch | ||
* @v data Buffer to fill with setting data | ||
* @v len Length of buffer | ||
* @ret len Length of setting data, or negative error | ||
*/ | ||
static int acpi_settings_fetch ( struct settings *settings, | ||
struct setting *setting, | ||
void *data, size_t len ) { | ||
struct acpi_header acpi; | ||
uint32_t tag_high; | ||
uint32_t tag_low; | ||
uint32_t tag_signature; | ||
unsigned int tag_index; | ||
size_t tag_offset; | ||
size_t tag_len; | ||
userptr_t table; | ||
size_t offset; | ||
size_t max_len; | ||
int delta; | ||
unsigned int i; | ||
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/* Parse settings tag */ | ||
tag_high = ( setting->tag >> 32 ); | ||
tag_low = setting->tag; | ||
tag_signature = bswap_32 ( tag_high ); | ||
tag_index = ( ( tag_low >> 24 ) & 0xff ); | ||
tag_offset = ( ( tag_low >> 8 ) & 0xffff ); | ||
tag_len = ( ( tag_low >> 0 ) & 0xff ); | ||
DBGC ( settings, "ACPI %s.%d offset %#zx length %#zx\n", | ||
acpi_name ( tag_signature ), tag_index, tag_offset, tag_len ); | ||
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/* Locate ACPI table */ | ||
table = acpi_find ( tag_signature, tag_index ); | ||
if ( ! table ) | ||
return -ENOENT; | ||
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/* Read table header */ | ||
copy_from_user ( &acpi, table, 0, sizeof ( acpi ) ); | ||
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/* Calculate starting offset and maximum available length */ | ||
max_len = le32_to_cpu ( acpi.length ); | ||
if ( tag_offset > max_len ) | ||
return -ENOENT; | ||
offset = tag_offset; | ||
max_len -= offset; | ||
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/* Restrict to requested length, if specified */ | ||
if ( tag_len && ( tag_len < max_len ) ) | ||
max_len = tag_len; | ||
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/* Invert endianness for numeric settings */ | ||
if ( setting->type && setting->type->numerate ) { | ||
offset += ( max_len - 1 ); | ||
delta = -1; | ||
} else { | ||
delta = +1; | ||
} | ||
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/* Read data */ | ||
for ( i = 0 ; ( ( i < max_len ) && ( i < len ) ) ; i++ ) { | ||
copy_from_user ( data, table, offset, 1 ); | ||
data++; | ||
offset += delta; | ||
} | ||
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/* Set type if not already specified */ | ||
if ( ! setting->type ) | ||
setting->type = &setting_type_hexraw; | ||
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return max_len; | ||
} | ||
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/** ACPI settings operations */ | ||
static struct settings_operations acpi_settings_operations = { | ||
.applies = acpi_settings_applies, | ||
.fetch = acpi_settings_fetch, | ||
}; | ||
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/** ACPI settings */ | ||
static struct settings acpi_settings = { | ||
.refcnt = NULL, | ||
.siblings = LIST_HEAD_INIT ( acpi_settings.siblings ), | ||
.children = LIST_HEAD_INIT ( acpi_settings.children ), | ||
.op = &acpi_settings_operations, | ||
.default_scope = &acpi_settings_scope, | ||
}; | ||
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/** Initialise ACPI settings */ | ||
static void acpi_settings_init ( void ) { | ||
int rc; | ||
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if ( ( rc = register_settings ( &acpi_settings, NULL, | ||
"acpi" ) ) != 0 ) { | ||
DBG ( "ACPI could not register settings: %s\n", | ||
strerror ( rc ) ); | ||
return; | ||
} | ||
} | ||
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/** ACPI settings initialiser */ | ||
struct init_fn acpi_settings_init_fn __init_fn ( INIT_NORMAL ) = { | ||
.initialise = acpi_settings_init, | ||
}; |
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