lib/acpi/acpigen.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Generation of ACPI (Advanced Configuration and Power Interface) tables
 *
 * Copyright 2019 Google LLC
 * Mostly taken from coreboot
 */

#define LOG_CATEGORY LOGC_ACPI

#include <common.h>
#include <dm.h>
#include <log.h>
#include <acpi/acpigen.h>
#include <dm/acpi.h>

u8 *acpigen_get_current(struct acpi_ctx *ctx)
{
	return ctx->current;
}

void acpigen_emit_byte(struct acpi_ctx *ctx, uint data)
{
	*(u8 *)ctx->current++ = data;
}

void acpigen_emit_word(struct acpi_ctx *ctx, uint data)
{
	acpigen_emit_byte(ctx, data & 0xff);
	acpigen_emit_byte(ctx, (data >> 8) & 0xff);
}

void acpigen_emit_dword(struct acpi_ctx *ctx, uint data)
{
	/* Output the value in little-endian format */
	acpigen_emit_byte(ctx, data & 0xff);
	acpigen_emit_byte(ctx, (data >> 8) & 0xff);
	acpigen_emit_byte(ctx, (data >> 16) & 0xff);
	acpigen_emit_byte(ctx, (data >> 24) & 0xff);
}

/*
 * Maximum length for an ACPI object generated by this code,
 *
 * If you need to change this, change acpigen_write_len_f(ctx) and
 * acpigen_pop_len(ctx)
 */
#define ACPIGEN_MAXLEN 0xfffff

void acpigen_write_len_f(struct acpi_ctx *ctx)
{
	assert(ctx->ltop < (ACPIGEN_LENSTACK_SIZE - 1));
	ctx->len_stack[ctx->ltop++] = ctx->current;
	acpigen_emit_byte(ctx, 0);
	acpigen_emit_byte(ctx, 0);
	acpigen_emit_byte(ctx, 0);
}

void acpigen_pop_len(struct acpi_ctx *ctx)
{
	int len;
	char *p;

	assert(ctx->ltop > 0);
	p = ctx->len_stack[--ctx->ltop];
	len = ctx->current - (void *)p;
	assert(len <= ACPIGEN_MAXLEN);
	/* generate store length for 0xfffff max */
	p[0] = ACPI_PKG_LEN_3_BYTES | (len & 0xf);
	p[1] = len >> 4 & 0xff;
	p[2] = len >> 12 & 0xff;
}

char *acpigen_write_package(struct acpi_ctx *ctx, int nr_el)
{
	char *p;

	acpigen_emit_byte(ctx, PACKAGE_OP);
	acpigen_write_len_f(ctx);
	p = ctx->current;
	acpigen_emit_byte(ctx, nr_el);

	return p;
}

void acpigen_write_byte(struct acpi_ctx *ctx, unsigned int data)
{
	acpigen_emit_byte(ctx, BYTE_PREFIX);
	acpigen_emit_byte(ctx, data & 0xff);
}

void acpigen_write_word(struct acpi_ctx *ctx, unsigned int data)
{
	acpigen_emit_byte(ctx, WORD_PREFIX);
	acpigen_emit_word(ctx, data);
}

void acpigen_write_dword(struct acpi_ctx *ctx, unsigned int data)
{
	acpigen_emit_byte(ctx, DWORD_PREFIX);
	acpigen_emit_dword(ctx, data);
}

void acpigen_write_qword(struct acpi_ctx *ctx, u64 data)
{
	acpigen_emit_byte(ctx, QWORD_PREFIX);
	acpigen_emit_dword(ctx, data & 0xffffffff);
	acpigen_emit_dword(ctx, (data >> 32) & 0xffffffff);
}

void acpigen_write_zero(struct acpi_ctx *ctx)
{
	acpigen_emit_byte(ctx, ZERO_OP);
}

void acpigen_write_one(struct acpi_ctx *ctx)
{
	acpigen_emit_byte(ctx, ONE_OP);
}

void acpigen_write_integer(struct acpi_ctx *ctx, u64 data)
{
	if (data == 0)
		acpigen_write_zero(ctx);
	else if (data == 1)
		acpigen_write_one(ctx);
	else if (data <= 0xff)
		acpigen_write_byte(ctx, (unsigned char)data);
	else if (data <= 0xffff)
		acpigen_write_word(ctx, (unsigned int)data);
	else if (data <= 0xffffffff)
		acpigen_write_dword(ctx, (unsigned int)data);
	else
		acpigen_write_qword(ctx, data);
}

void acpigen_emit_stream(struct acpi_ctx *ctx, const char *data, int size)
{
	int i;

	for (i = 0; i < size; i++)
		acpigen_emit_byte(ctx, data[i]);
}

void acpigen_emit_string(struct acpi_ctx *ctx, const char *str)
{
	acpigen_emit_stream(ctx, str, str ? strlen(str) : 0);
	acpigen_emit_byte(ctx, '\0');
}

void acpigen_write_string(struct acpi_ctx *ctx, const char *str)
{
	acpigen_emit_byte(ctx, STRING_PREFIX);
	acpigen_emit_string(ctx, str);
}

/*
 * The naming conventions for ACPI namespace names are a bit tricky as
 * each element has to be 4 chars wide ("All names are a fixed 32 bits.")
 * and "By convention, when an ASL compiler pads a name shorter than 4
 * characters, it is done so with trailing underscores ('_')".
 *
 * Check sections 5.3, 20.2.2 and 20.4 of ACPI spec 6.3 for details.
 */
static void acpigen_emit_simple_namestring(struct acpi_ctx *ctx,
					   const char *name)
{
	const char *ptr;
	int i;

	for (i = 0, ptr = name; i < 4; i++) {
		if (!*ptr || *ptr == '.')
			acpigen_emit_byte(ctx, '_');
		else
			acpigen_emit_byte(ctx, *ptr++);
	}
}

static void acpigen_emit_double_namestring(struct acpi_ctx *ctx,
					   const char *name, int dotpos)
{
	acpigen_emit_byte(ctx, DUAL_NAME_PREFIX);
	acpigen_emit_simple_namestring(ctx, name);
	acpigen_emit_simple_namestring(ctx, &name[dotpos + 1]);
}

static void acpigen_emit_multi_namestring(struct acpi_ctx *ctx,
					  const char *name)
{
	unsigned char *pathlen;
	int count = 0;

	acpigen_emit_byte(ctx, MULTI_NAME_PREFIX);
	pathlen = ctx->current;
	acpigen_emit_byte(ctx, 0);

	while (*name) {
		acpigen_emit_simple_namestring(ctx, name);
		/* find end or next entity */
		while (*name != '.' && *name)
			name++;
		/* forward to next */
		if (*name == '.')
			name++;
		count++;
	}

	*pathlen = count;
}

void acpigen_emit_namestring(struct acpi_ctx *ctx, const char *namepath)
{
	int dotcount;
	int dotpos;
	int i;

	/* We can start with a '\' */
	if (*namepath == '\\') {
		acpigen_emit_byte(ctx, '\\');
		namepath++;
	}

	/* And there can be any number of '^' */
	while (*namepath == '^') {
		acpigen_emit_byte(ctx, '^');
		namepath++;
	}

	for (i = 0, dotcount = 0; namepath[i]; i++) {
		if (namepath[i] == '.') {
			dotcount++;
			dotpos = i;
		}
	}

	/* If we have only \\ or only ^* then we need to add a null name */
	if (!*namepath)
		acpigen_emit_byte(ctx, ZERO_OP);
	else if (dotcount == 0)
		acpigen_emit_simple_namestring(ctx, namepath);
	else if (dotcount == 1)
		acpigen_emit_double_namestring(ctx, namepath, dotpos);
	else
		acpigen_emit_multi_namestring(ctx, namepath);
}

void acpigen_write_name(struct acpi_ctx *ctx, const char *namepath)
{
	acpigen_emit_byte(ctx, NAME_OP);
	acpigen_emit_namestring(ctx, namepath);
}