src/acpi/acpigen.c

/* SPDX-License-Identifier: GPL-2.0-only */
/* This file is part of the coreboot project. */

/* How much nesting do we support? */
#define ACPIGEN_LENSTACK_SIZE 10

/*
 * If you need to change this, change acpigen_write_len_f and
 * acpigen_pop_len
 */

#define ACPIGEN_MAXLEN 0xfffff

#include <lib.h>
#include <string.h>
#include <acpi/acpigen.h>
#include <assert.h>
#include <console/console.h>
#include <device/device.h>
#include <device/pci_def.h>
#include <device/pci_type.h>

static char *gencurrent;

char *len_stack[ACPIGEN_LENSTACK_SIZE];
int ltop = 0;

void acpigen_write_len_f(void)
{
	ASSERT(ltop < (ACPIGEN_LENSTACK_SIZE - 1))
	len_stack[ltop++] = gencurrent;
	acpigen_emit_byte(0);
	acpigen_emit_byte(0);
	acpigen_emit_byte(0);
}

void acpigen_pop_len(void)
{
	int len;
	ASSERT(ltop > 0)
	char *p = len_stack[--ltop];
	len = gencurrent - p;
	ASSERT(len <= ACPIGEN_MAXLEN)
	/* generate store length for 0xfffff max */
	p[0] = (0x80 | (len & 0xf));
	p[1] = (len >> 4 & 0xff);
	p[2] = (len >> 12 & 0xff);

}

void acpigen_set_current(char *curr)
{
	gencurrent = curr;
}

char *acpigen_get_current(void)
{
	return gencurrent;
}

void acpigen_emit_byte(unsigned char b)
{
	(*gencurrent++) = b;
}

void acpigen_emit_ext_op(uint8_t op)
{
	acpigen_emit_byte(EXT_OP_PREFIX);
	acpigen_emit_byte(op);
}

void acpigen_emit_word(unsigned int data)
{
	acpigen_emit_byte(data & 0xff);
	acpigen_emit_byte((data >> 8) & 0xff);
}

void acpigen_emit_dword(unsigned int data)
{
	acpigen_emit_byte(data & 0xff);
	acpigen_emit_byte((data >> 8) & 0xff);
	acpigen_emit_byte((data >> 16) & 0xff);
	acpigen_emit_byte((data >> 24) & 0xff);
}

char *acpigen_write_package(int nr_el)
{
	char *p;
	acpigen_emit_byte(PACKAGE_OP);
	acpigen_write_len_f();
	p = acpigen_get_current();
	acpigen_emit_byte(nr_el);
	return p;
}

void acpigen_write_byte(unsigned int data)
{
	acpigen_emit_byte(BYTE_PREFIX);
	acpigen_emit_byte(data & 0xff);
}

void acpigen_write_word(unsigned int data)
{
	acpigen_emit_byte(WORD_PREFIX);
	acpigen_emit_word(data);
}

void acpigen_write_dword(unsigned int data)
{
	acpigen_emit_byte(DWORD_PREFIX);
	acpigen_emit_dword(data);
}

void acpigen_write_qword(uint64_t data)
{
	acpigen_emit_byte(QWORD_PREFIX);
	acpigen_emit_dword(data & 0xffffffff);
	acpigen_emit_dword((data >> 32) & 0xffffffff);
}

void acpigen_write_zero(void)
{
	acpigen_emit_byte(ZERO_OP);
}

void acpigen_write_one(void)
{
	acpigen_emit_byte(ONE_OP);
}

void acpigen_write_ones(void)
{
	acpigen_emit_byte(ONES_OP);
}

void acpigen_write_integer(uint64_t data)
{
	if (data == 0)
		acpigen_write_zero();
	else if (data == 1)
		acpigen_write_one();
	else if (data <= 0xff)
		acpigen_write_byte((unsigned char)data);
	else if (data <= 0xffff)
		acpigen_write_word((unsigned int)data);
	else if (data <= 0xffffffff)
		acpigen_write_dword((unsigned int)data);
	else
		acpigen_write_qword(data);
}

void acpigen_write_name_zero(const char *name)
{
	acpigen_write_name(name);
	acpigen_write_one();
}

void acpigen_write_name_one(const char *name)
{
	acpigen_write_name(name);
	acpigen_write_zero();
}

void acpigen_write_name_byte(const char *name, uint8_t val)
{
	acpigen_write_name(name);
	acpigen_write_byte(val);
}

void acpigen_write_name_dword(const char *name, uint32_t val)
{
	acpigen_write_name(name);
	acpigen_write_dword(val);
}

void acpigen_write_name_qword(const char *name, uint64_t val)
{
	acpigen_write_name(name);
	acpigen_write_qword(val);
}

void acpigen_write_name_integer(const char *name, uint64_t val)
{
	acpigen_write_name(name);
	acpigen_write_integer(val);
}

void acpigen_write_name_string(const char *name, const char *string)
{
	acpigen_write_name(name);
	acpigen_write_string(string);
}

void acpigen_write_name_unicode(const char *name, const char *string)
{
	const size_t len = strlen(string) + 1;
	acpigen_write_name(name);
	acpigen_emit_byte(BUFFER_OP);
	acpigen_write_len_f();
	acpigen_write_integer(len);
	for (size_t i = 0; i < len; i++) {
		const char c = string[i];
		/* Simple ASCII to UTF-16 conversion, replace non ASCII characters */
		acpigen_emit_word(c >= 0 ? c : '?');
	}
	acpigen_pop_len();
}

void acpigen_emit_stream(const char *data, int size)
{
	int i;
	for (i = 0; i < size; i++)
		acpigen_emit_byte(data[i]);
}

void acpigen_emit_string(const char *string)
{
	acpigen_emit_stream(string, string ? strlen(string) : 0);
	acpigen_emit_byte('\0'); /* NUL */
}

void acpigen_write_string(const char *string)
{
	acpigen_emit_byte(STRING_PREFIX);
	acpigen_emit_string(string);
}

void acpigen_write_coreboot_hid(enum coreboot_acpi_ids id)
{
	char hid[9]; /* BOOTxxxx */

	snprintf(hid, sizeof(hid), "%.4s%04X", COREBOOT_ACPI_ID, id);
	acpigen_write_name_string("_HID", hid);
}

/*
 * 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, 18.2.2 and 18.4 of ACPI spec 3.0 for details.
 */

static void acpigen_emit_simple_namestring(const char *name)
{
	int i;
	char ud[] = "____";
	for (i = 0; i < 4; i++) {
		if ((name[i] == '\0') || (name[i] == '.')) {
			acpigen_emit_stream(ud, 4 - i);
			break;
		}
		acpigen_emit_byte(name[i]);
	}
}

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

static void acpigen_emit_multi_namestring(const char *name)
{
	int count = 0;
	unsigned char *pathlen;
	acpigen_emit_byte(MULTI_NAME_PREFIX);
	acpigen_emit_byte(ZERO_OP);
	pathlen = ((unsigned char *) acpigen_get_current()) - 1;

	while (name[0] != '\0') {
		acpigen_emit_simple_namestring(name);
		/* find end or next entity */
		while ((name[0] != '.') && (name[0] != '\0'))
			name++;
		/* forward to next */
		if (name[0] == '.')
			name++;
		count++;
	}

	pathlen[0] = count;
}


void acpigen_emit_namestring(const char *namepath)
{
	int dotcount = 0, i;
	int dotpos = 0;

	/* We can start with a '\'. */
	if (namepath[0] == '\\') {
		acpigen_emit_byte('\\');
		namepath++;
	}

	/* And there can be any number of '^' */
	while (namepath[0] == '^') {
		acpigen_emit_byte('^');
		namepath++;
	}

	/* If we have only \\ or only ^...^. Then we need to put a null
	   name (0x00). */
	if (namepath[0] == '\0') {
		acpigen_emit_byte(ZERO_OP);
		return;
	}

	i = 0;
	while (namepath[i] != '\0') {
		if (namepath[i] == '.') {
			dotcount++;
			dotpos = i;
		}
		i++;
	}

	if (dotcount == 0)
		acpigen_emit_simple_namestring(namepath);
	else if (dotcount == 1)
		acpigen_emit_double_namestring(namepath, dotpos);
	else
		acpigen_emit_multi_namestring(namepath);
}

void acpigen_write_name(const char *name)
{
	acpigen_emit_byte(NAME_OP);
	acpigen_emit_namestring(name);
}

void acpigen_write_scope(const char *name)
{
	acpigen_emit_byte(SCOPE_OP);
	acpigen_write_len_f();
	acpigen_emit_namestring(name);
}

void acpigen_write_processor(u8 cpuindex, u32 pblock_addr, u8 pblock_len)
{
/*
	Processor (\_SB.CPcpuindex, cpuindex, pblock_addr, pblock_len)
	{
*/
	char pscope[16];
	acpigen_emit_ext_op(PROCESSOR_OP);
	acpigen_write_len_f();

	snprintf(pscope, sizeof(pscope),
		 CONFIG_ACPI_CPU_STRING, (unsigned int) cpuindex);
	acpigen_emit_namestring(pscope);
	acpigen_emit_byte(cpuindex);
	acpigen_emit_dword(pblock_addr);
	acpigen_emit_byte(pblock_len);
}

void acpigen_write_processor_package(const char *const name,
				     const unsigned int first_core,
				     const unsigned int core_count)
{
	unsigned int i;
	char pscope[16];

	acpigen_write_name(name);
	acpigen_write_package(core_count);
	for (i = first_core; i < first_core + core_count; ++i) {
		snprintf(pscope, sizeof(pscope), CONFIG_ACPI_CPU_STRING, i);
		acpigen_emit_namestring(pscope);
	}
	acpigen_pop_len();
}

/* Method to notify all CPU cores */
void acpigen_write_processor_cnot(const unsigned int number_of_cores)
{
	int core_id;

	acpigen_write_method("\\_SB.CNOT", 1);
	for (core_id = 0; core_id < number_of_cores; core_id++) {
		char buffer[DEVICE_PATH_MAX];
		snprintf(buffer, sizeof(buffer), CONFIG_ACPI_CPU_STRING,
			 core_id);
		acpigen_emit_byte(NOTIFY_OP);
		acpigen_emit_namestring(buffer);
		acpigen_emit_byte(ARG0_OP);
	}
	acpigen_pop_len();
}

/*
 * Generate ACPI AML code for OperationRegion
 * Arg0: Pointer to struct opregion opreg = OPREGION(rname, space, offset, len)
 * where rname is region name, space is region space, offset is region offset &
 * len is region length.
 * OperationRegion(regionname, regionspace, regionoffset, regionlength)
 */
void acpigen_write_opregion(struct opregion *opreg)
{
	/* OpregionOp */
	acpigen_emit_ext_op(OPREGION_OP);
	/* NameString 4 chars only */
	acpigen_emit_simple_namestring(opreg->name);
	/* RegionSpace */
	acpigen_emit_byte(opreg->regionspace);
	/* RegionOffset & RegionLen, it can be byte word or double word */
	acpigen_write_integer(opreg->regionoffset);
	acpigen_write_integer(opreg->regionlen);
}

/*
 * Generate ACPI AML code for Mutex
 * Arg0: Pointer to name of mutex
 * Arg1: Initial value of mutex
 */
void acpigen_write_mutex(const char *name, const uint8_t flags)
{
	/* MutexOp */
	acpigen_emit_ext_op(MUTEX_OP);
	/* NameString 4 chars only */
	acpigen_emit_simple_namestring(name);
	acpigen_emit_byte(flags);
}

void acpigen_write_acquire(const char *name, const uint16_t val)
{
	/* AcquireOp */
	acpigen_emit_ext_op(ACQUIRE_OP);
	/* NameString 4 chars only */
	acpigen_emit_simple_namestring(name);
	acpigen_emit_word(val);
}

void acpigen_write_release(const char *name)
{
	/* ReleaseOp */
	acpigen_emit_ext_op(RELEASE_OP);
	/* NameString 4 chars only */
	acpigen_emit_simple_namestring(name);
}

static void acpigen_write_field_length(uint32_t len)
{
	uint8_t i, j;
	uint8_t emit[4];

	i = 1;
	if (len < 0x40) {
		emit[0] = len & 0x3F;
	} else {
		emit[0] = len & 0xF;
		len >>= 4;
		while (len) {
			emit[i] = len & 0xFF;
			i++;
			len >>= 8;
		}
	}
	/* Update bit 7:6 : Number of bytes followed by emit[0] */
	emit[0] |= (i - 1) << 6;

	for (j = 0; j < i; j++)
		acpigen_emit_byte(emit[j]);
}

static void acpigen_write_field_offset(uint32_t offset,
				       uint32_t current_bit_pos)
{
	uint32_t diff_bits;

	if (offset < current_bit_pos) {
		printk(BIOS_WARNING, "%s: Cannot move offset backward",
			__func__);
		return;
	}

	diff_bits = offset - current_bit_pos;
	/* Upper limit */
	if (diff_bits > 0xFFFFFFF) {
		printk(BIOS_WARNING, "%s: Offset very large to encode",
			__func__);
		return;
	}

	acpigen_emit_byte(0);
	acpigen_write_field_length(diff_bits);
}

static void acpigen_write_field_name(const char *name, uint32_t size)
{
	acpigen_emit_simple_namestring(name);
	acpigen_write_field_length(size);
}

/*
 * Generate ACPI AML code for Field
 * Arg0: region name
 * Arg1: Pointer to struct fieldlist.
 * Arg2: no. of entries in Arg1
 * Arg3: flags which indicate filed access type, lock rule  & update rule.
 * Example with fieldlist
 * struct fieldlist l[] = {
 *	FIELDLIST_OFFSET(0x84),
 *	FIELDLIST_NAMESTR("PMCS", 2),
 *	};
 * acpigen_write_field("UART", l, ARRAY_SIZE(l), FIELD_ANYACC | FIELD_NOLOCK |
 *								FIELD_PRESERVE);
 * Output:
 * Field (UART, AnyAcc, NoLock, Preserve)
 *	{
 *		Offset (0x84),
 *		PMCS,   2
 *	}
 */
void acpigen_write_field(const char *name, const struct fieldlist *l, size_t count,
			 uint8_t flags)
{
	uint16_t i;
	uint32_t current_bit_pos = 0;

	/* FieldOp */
	acpigen_emit_ext_op(FIELD_OP);
	/* Package Length */
	acpigen_write_len_f();
	/* NameString 4 chars only */
	acpigen_emit_simple_namestring(name);
	/* Field Flag */
	acpigen_emit_byte(flags);

	for (i = 0; i < count; i++) {
		switch (l[i].type) {
		case NAME_STRING:
			acpigen_write_field_name(l[i].name, l[i].bits);
			current_bit_pos += l[i].bits;
			break;
		case OFFSET:
			acpigen_write_field_offset(l[i].bits, current_bit_pos);
			current_bit_pos = l[i].bits;
			break;
		default:
			printk(BIOS_ERR, "%s: Invalid field type 0x%X\n"
				, __func__, l[i].type);
			break;
		}
	}
	acpigen_pop_len();
}

/*
 * Generate ACPI AML code for IndexField
 * Arg0: region name
 * Arg1: Pointer to struct fieldlist.
 * Arg2: no. of entries in Arg1
 * Arg3: flags which indicate filed access type, lock rule  & update rule.
 * Example with fieldlist
 * struct fieldlist l[] = {
 *	FIELDLIST_OFFSET(0x84),
 *	FIELDLIST_NAMESTR("PMCS", 2),
 *	};
 * acpigen_write_field("IDX", "DATA" l, ARRAY_SIZE(l), FIELD_ANYACC |
 *						       FIELD_NOLOCK |
 *						       FIELD_PRESERVE);
 * Output:
 * IndexField (IDX, DATA, AnyAcc, NoLock, Preserve)
 *	{
 *		Offset (0x84),
 *		PMCS,   2
 *	}
 */
void acpigen_write_indexfield(const char *idx, const char *data,
			      struct fieldlist *l, size_t count, uint8_t flags)
{
	uint16_t i;
	uint32_t current_bit_pos = 0;

	/* FieldOp */
	acpigen_emit_ext_op(INDEX_FIELD_OP);
	/* Package Length */
	acpigen_write_len_f();
	/* NameString 4 chars only */
	acpigen_emit_simple_namestring(idx);
	/* NameString 4 chars only */
	acpigen_emit_simple_namestring(data);
	/* Field Flag */
	acpigen_emit_byte(flags);

	for (i = 0; i < count; i++) {
		switch (l[i].type) {
		case NAME_STRING:
			acpigen_write_field_name(l[i].name, l[i].bits);
			current_bit_pos += l[i].bits;
			break;
		case OFFSET:
			acpigen_write_field_offset(l[i].bits, current_bit_pos);
			current_bit_pos = l[i].bits;
			break;
		default:
			printk(BIOS_ERR, "%s: Invalid field type 0x%X\n"
				, __func__, l[i].type);
			break;
		}
	}
	acpigen_pop_len();
}

void acpigen_write_empty_PCT(void)
{
/*
	Name (_PCT, Package (0x02)
	{
		ResourceTemplate ()
		{
			Register (FFixedHW,
				0x00,               // Bit Width
				0x00,               // Bit Offset
				0x0000000000000000, // Address
				,)
		},

		ResourceTemplate ()
		{
			Register (FFixedHW,
				0x00,               // Bit Width
				0x00,               // Bit Offset
				0x0000000000000000, // Address
				,)
		}
	})
*/
	static char stream[] = {
		/* 00000030    "0._PCT.," */
		0x08, 0x5F, 0x50, 0x43, 0x54, 0x12, 0x2C,
		/* 00000038    "........" */
		0x02, 0x11, 0x14, 0x0A, 0x11, 0x82, 0x0C, 0x00,
		/* 00000040    "........" */
		0x7F, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		/* 00000048    "....y..." */
		0x00, 0x00, 0x00, 0x00, 0x79, 0x00, 0x11, 0x14,
		/* 00000050    "........" */
		0x0A, 0x11, 0x82, 0x0C, 0x00, 0x7F, 0x00, 0x00,
		/* 00000058    "........" */
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x79, 0x00
	};
	acpigen_emit_stream(stream, ARRAY_SIZE(stream));
}

void acpigen_write_empty_PTC(void)
{
/*
	Name (_PTC, Package (0x02)
	{
		ResourceTemplate ()
		{
			Register (FFixedHW,
				0x00,               // Bit Width
				0x00,               // Bit Offset
				0x0000000000000000, // Address
				,)
		},

		ResourceTemplate ()
		{
			Register (FFixedHW,
				0x00,               // Bit Width
				0x00,               // Bit Offset
				0x0000000000000000, // Address
				,)
		}
	})
*/
	acpi_addr_t addr = {
		.space_id    = ACPI_ADDRESS_SPACE_FIXED,
		.bit_width   = 0,
		.bit_offset  = 0,
		.access_size = 0,
		.addrl       = 0,
		.addrh       = 0,
	};

	acpigen_write_name("_PTC");
	acpigen_write_package(2);

	/* ControlRegister */
	acpigen_write_register_resource(&addr);

	/* StatusRegister */
	acpigen_write_register_resource(&addr);

	acpigen_pop_len();
}

static void __acpigen_write_method(const char *name, uint8_t flags)
{
	acpigen_emit_byte(METHOD_OP);
	acpigen_write_len_f();
	acpigen_emit_namestring(name);
	acpigen_emit_byte(flags);
}

/* Method (name, nargs, NotSerialized) */
void acpigen_write_method(const char *name, int nargs)
{
	__acpigen_write_method(name, (nargs & 7));
}

/* Method (name, nargs, Serialized) */
void acpigen_write_method_serialized(const char *name, int nargs)
{
	__acpigen_write_method(name, (nargs & 7) | (1 << 3));
}

void acpigen_write_device(const char *name)
{
	acpigen_emit_ext_op(DEVICE_OP);
	acpigen_write_len_f();
	acpigen_emit_namestring(name);
}

void acpigen_write_STA(uint8_t status)
{
	/*
	 * Method (_STA, 0, NotSerialized) { Return (status) }
	 */
	acpigen_write_method("_STA", 0);
	acpigen_emit_byte(RETURN_OP);
	acpigen_write_byte(status);
	acpigen_pop_len();
}

/*
 * Generates a func with max supported P-states.
 */
void acpigen_write_PPC(u8 nr)
{
/*
	Method (_PPC, 0, NotSerialized)
	{
		Return (nr)
	}
*/
	acpigen_write_method("_PPC", 0);
	acpigen_emit_byte(RETURN_OP);
	/* arg */
	acpigen_write_byte(nr);
	acpigen_pop_len();
}

/*
 * Generates a func with max supported P-states saved
 * in the variable PPCM.
 */
void acpigen_write_PPC_NVS(void)
{
/*
	Method (_PPC, 0, NotSerialized)
	{
		Return (PPCM)
	}
*/
	acpigen_write_method("_PPC", 0);
	acpigen_emit_byte(RETURN_OP);
	/* arg */
	acpigen_emit_namestring("PPCM");
	acpigen_pop_len();
}

void acpigen_write_TPC(const char *gnvs_tpc_limit)
{
/*
	// Sample _TPC method
	Method (_TPC, 0, NotSerialized)
	{
		Return (\TLVL)
	}
*/
	acpigen_write_method("_TPC", 0);
	acpigen_emit_byte(RETURN_OP);
	acpigen_emit_namestring(gnvs_tpc_limit);
	acpigen_pop_len();
}

void acpigen_write_PRW(u32 wake, u32 level)
{
	/*
	 * Name (_PRW, Package () { wake, level }
	 */
	acpigen_write_name("_PRW");
	acpigen_write_package(2);
	acpigen_write_integer(wake);
	acpigen_write_integer(level);
	acpigen_pop_len();
}

void acpigen_write_PSS_package(u32 coreFreq, u32 power, u32 transLat,
			      u32 busmLat, u32 control, u32 status)
{
	acpigen_write_package(6);
	acpigen_write_dword(coreFreq);
	acpigen_write_dword(power);
	acpigen_write_dword(transLat);
	acpigen_write_dword(busmLat);
	acpigen_write_dword(control);
	acpigen_write_dword(status);
	acpigen_pop_len();

	printk(BIOS_DEBUG, "PSS: %uMHz power %u control 0x%x status 0x%x\n",
	       coreFreq, power, control, status);
}

void acpigen_write_PSD_package(u32 domain, u32 numprocs, PSD_coord coordtype)
{
	acpigen_write_name("_PSD");
	acpigen_write_package(1);
	acpigen_write_package(5);
	acpigen_write_byte(5);	// 5 values
	acpigen_write_byte(0);	// revision 0
	acpigen_write_dword(domain);
	acpigen_write_dword(coordtype);
	acpigen_write_dword(numprocs);
	acpigen_pop_len();
	acpigen_pop_len();
}

void acpigen_write_CST_package_entry(acpi_cstate_t *cstate)
{
	acpigen_write_package(4);
	acpigen_write_register_resource(&cstate->resource);
	acpigen_write_dword(cstate->ctype);
	acpigen_write_dword(cstate->latency);
	acpigen_write_dword(cstate->power);
	acpigen_pop_len();
}

void acpigen_write_CST_package(acpi_cstate_t *cstate, int nentries)
{
	int i;
	acpigen_write_name("_CST");
	acpigen_write_package(nentries+1);
	acpigen_write_dword(nentries);

	for (i = 0; i < nentries; i++)
		acpigen_write_CST_package_entry(cstate + i);

	acpigen_pop_len();
}

void acpigen_write_CSD_package(u32 domain, u32 numprocs, CSD_coord coordtype,
	u32 index)
{
	acpigen_write_name("_CSD");
	acpigen_write_package(1);
	acpigen_write_package(6);
	acpigen_write_byte(6);	// 6 values
	acpigen_write_byte(0);	// revision 0
	acpigen_write_dword(domain);
	acpigen_write_dword(coordtype);
	acpigen_write_dword(numprocs);
	acpigen_write_dword(index);
	acpigen_pop_len();
	acpigen_pop_len();
}

void acpigen_write_TSS_package(int entries, acpi_tstate_t *tstate_list)
{
/*
	Sample _TSS package with 100% and 50% duty cycles
	Name (_TSS, Package (0x02)
	{
		Package(){100, 1000, 0, 0x00, 0)
		Package(){50, 520, 0, 0x18, 0)
	})
*/
	int i;
	acpi_tstate_t *tstate = tstate_list;

	acpigen_write_name("_TSS");
	acpigen_write_package(entries);

	for (i = 0; i < entries; i++) {
		acpigen_write_package(5);
		acpigen_write_dword(tstate->percent);
		acpigen_write_dword(tstate->power);
		acpigen_write_dword(tstate->latency);
		acpigen_write_dword(tstate->control);
		acpigen_write_dword(tstate->status);
		acpigen_pop_len();
		tstate++;
	}

	acpigen_pop_len();
}

void acpigen_write_TSD_package(u32 domain, u32 numprocs, PSD_coord coordtype)
{
	acpigen_write_name("_TSD");
	acpigen_write_package(1);
	acpigen_write_package(5);
	acpigen_write_byte(5);	// 5 values
	acpigen_write_byte(0);	// revision 0
	acpigen_write_dword(domain);
	acpigen_write_dword(coordtype);
	acpigen_write_dword(numprocs);
	acpigen_pop_len();
	acpigen_pop_len();
}



void acpigen_write_mem32fixed(int readwrite, u32 base, u32 size)
{
	/*
	 * ACPI 4.0 section 6.4.3.4: 32-Bit Fixed Memory Range Descriptor
	 * Byte 0:
	 *   Bit7  : 1 => big item
	 *   Bit6-0: 0000110 (0x6) => 32-bit fixed memory
	 */
	acpigen_emit_byte(0x86);
	/* Byte 1+2: length (0x0009) */
	acpigen_emit_byte(0x09);
	acpigen_emit_byte(0x00);
	/* bit1-7 are ignored */
	acpigen_emit_byte(readwrite ? 0x01 : 0x00);
	acpigen_emit_dword(base);
	acpigen_emit_dword(size);
}

static void acpigen_write_register(const acpi_addr_t *addr)
{
	acpigen_emit_byte(0x82);		/* Register Descriptor */
	acpigen_emit_byte(0x0c);		/* Register Length 7:0 */
	acpigen_emit_byte(0x00);		/* Register Length 15:8 */
	acpigen_emit_byte(addr->space_id);	/* Address Space ID */
	acpigen_emit_byte(addr->bit_width);	/* Register Bit Width */
	acpigen_emit_byte(addr->bit_offset);	/* Register Bit Offset */
	acpigen_emit_byte(addr->access_size);	/* Register Access Size */
	acpigen_emit_dword(addr->addrl);	/* Register Address Low */
	acpigen_emit_dword(addr->addrh);	/* Register Address High */
}

void acpigen_write_register_resource(const acpi_addr_t *addr)
{
	acpigen_write_resourcetemplate_header();
	acpigen_write_register(addr);
	acpigen_write_resourcetemplate_footer();
}

void acpigen_write_irq(u16 mask)
{
	/*
	 * ACPI 3.0b section 6.4.2.1: IRQ Descriptor
	 * Byte 0:
	 *   Bit7  : 0 => small item
	 *   Bit6-3: 0100 (0x4) => IRQ port descriptor
	 *   Bit2-0: 010 (0x2) => 2 Bytes long
	 */
	acpigen_emit_byte(0x22);
	acpigen_emit_byte(mask & 0xff);
	acpigen_emit_byte((mask >> 8) & 0xff);
}

void acpigen_write_io16(u16 min, u16 max, u8 align, u8 len, u8 decode16)
{
	/*
	 * ACPI 4.0 section 6.4.2.6: I/O Port Descriptor
	 * Byte 0:
	 *   Bit7  : 0 => small item
	 *   Bit6-3: 1000 (0x8) => I/O port descriptor
	 *   Bit2-0: 111 (0x7) => 7 Bytes long
	 */
	acpigen_emit_byte(0x47);
	/* Does the device decode all 16 or just 10 bits? */
	/* bit1-7 are ignored */
	acpigen_emit_byte(decode16 ? 0x01 : 0x00);
	/* minimum base address the device may be configured for */
	acpigen_emit_byte(min & 0xff);
	acpigen_emit_byte((min >> 8) & 0xff);
	/* maximum base address the device may be configured for */
	acpigen_emit_byte(max & 0xff);
	acpigen_emit_byte((max >> 8) & 0xff);
	/* alignment for min base */
	acpigen_emit_byte(align & 0xff);
	acpigen_emit_byte(len & 0xff);
}

void acpigen_write_resourcetemplate_header(void)
{
	/*
	 * A ResourceTemplate() is a Buffer() with a
	 * (Byte|Word|DWord) containing the length, followed by one or more
	 * resource items, terminated by the end tag.
	 * (small item 0xf, len 1)
	 */
	acpigen_emit_byte(BUFFER_OP);
	acpigen_write_len_f();
	acpigen_emit_byte(WORD_PREFIX);
	len_stack[ltop++] = acpigen_get_current();
	/* Add 2 dummy bytes for the ACPI word (keep aligned with
	   the calculation in acpigen_write_resourcetemplate() below). */
	acpigen_emit_byte(0x00);
	acpigen_emit_byte(0x00);
}

void acpigen_write_resourcetemplate_footer(void)
{
	char *p = len_stack[--ltop];
	int len;
	/*
	 * end tag (acpi 4.0 Section 6.4.2.8)
	 * 0x79 <checksum>
	 * 0x00 is treated as a good checksum according to the spec
	 * and is what iasl generates.
	 */
	acpigen_emit_byte(0x79);
	acpigen_emit_byte(0x00);

	/* Start counting past the 2-bytes length added in
	   acpigen_write_resourcetemplate() above. */
	len = acpigen_get_current() - (p + 2);

	/* patch len word */
	p[0] = len & 0xff;
	p[1] = (len >> 8) & 0xff;
	/* patch len field */
	acpigen_pop_len();
}

static void acpigen_add_mainboard_rsvd_mem32(void *gp, struct device *dev,
						struct resource *res)
{
	acpigen_write_mem32fixed(0, res->base, res->size);
}

static void acpigen_add_mainboard_rsvd_io(void *gp, struct device *dev,
						struct resource *res)
{
	resource_t base = res->base;
	resource_t size = res->size;
	while (size > 0) {
		resource_t sz = size > 255 ? 255 : size;
		acpigen_write_io16(base, base, 0, sz, 1);
		size -= sz;
		base += sz;
	}
}

void acpigen_write_mainboard_resource_template(void)
{
	acpigen_write_resourcetemplate_header();

	/* Add reserved memory ranges. */
	search_global_resources(
		IORESOURCE_MEM | IORESOURCE_RESERVE,
		 IORESOURCE_MEM | IORESOURCE_RESERVE,
		acpigen_add_mainboard_rsvd_mem32, 0);

	/* Add reserved io ranges. */
	search_global_resources(
		IORESOURCE_IO | IORESOURCE_RESERVE,
		 IORESOURCE_IO | IORESOURCE_RESERVE,
		acpigen_add_mainboard_rsvd_io, 0);

	acpigen_write_resourcetemplate_footer();
}

void acpigen_write_mainboard_resources(const char *scope, const char *name)
{
	acpigen_write_scope(scope);
	acpigen_write_name(name);
	acpigen_write_mainboard_resource_template();
	acpigen_pop_len();
}

static int hex2bin(const char c)
{
	if (c >= 'A' && c <= 'F')
		return c - 'A' + 10;
	if (c >= 'a' && c <= 'f')
		return c - 'a' + 10;
	return c - '0';
}

void acpigen_emit_eisaid(const char *eisaid)
{
	u32 compact = 0;

	/* Clamping individual values would be better but
	   there is a disagreement over what is a valid
	   EISA id, so accept anything and don't clamp,
	   parent code should create a valid EISAid.
	 */
	compact |= (eisaid[0] - 'A' + 1) << 26;
	compact |= (eisaid[1] - 'A' + 1) << 21;
	compact |= (eisaid[2] - 'A' + 1) << 16;
	compact |= hex2bin(eisaid[3]) << 12;
	compact |= hex2bin(eisaid[4]) << 8;
	compact |= hex2bin(eisaid[5]) << 4;
	compact |= hex2bin(eisaid[6]);

	acpigen_emit_byte(0xc);
	acpigen_emit_byte((compact >> 24) & 0xff);
	acpigen_emit_byte((compact >> 16) & 0xff);
	acpigen_emit_byte((compact >> 8) & 0xff);
	acpigen_emit_byte(compact & 0xff);
}

/*
 * ToUUID(uuid)
 *
 * ACPI 6.1 Section 19.6.136 table 19-385 defines a special output
 * order for the bytes that make up a UUID Buffer object.
 * UUID byte order for input:
 *   aabbccdd-eeff-gghh-iijj-kkllmmnnoopp
 * UUID byte order for output:
 *   ddccbbaa-ffee-hhgg-iijj-kkllmmnnoopp
 */
#define UUID_LEN 16
void acpigen_write_uuid(const char *uuid)
{
	uint8_t buf[UUID_LEN];
	size_t i, order[UUID_LEN] = { 3, 2, 1, 0, 5, 4, 7, 6,
				      8, 9, 10, 11, 12, 13, 14, 15 };

	/* Parse UUID string into bytes */
	if (hexstrtobin(uuid, buf, UUID_LEN) < UUID_LEN)
		return;

	/* BufferOp */
	acpigen_emit_byte(BUFFER_OP);
	acpigen_write_len_f();

	/* Buffer length in bytes */
	acpigen_write_word(UUID_LEN);

	/* Output UUID in expected order */
	for (i = 0; i < UUID_LEN; i++)
		acpigen_emit_byte(buf[order[i]]);

	acpigen_pop_len();
}

/*
 * Name (_PRx, Package(One) { name })
 * ...
 * PowerResource (name, level, order)
 */
void acpigen_write_power_res(const char *name, uint8_t level, uint16_t order,
			     const char * const dev_states[], size_t dev_states_count)
{
	size_t i;
	for (i = 0; i < dev_states_count; i++) {
		acpigen_write_name(dev_states[i]);
		acpigen_write_package(1);
		acpigen_emit_simple_namestring(name);
		acpigen_pop_len();		/* Package */
	}

	acpigen_emit_ext_op(POWER_RES_OP);

	acpigen_write_len_f();

	acpigen_emit_simple_namestring(name);
	acpigen_emit_byte(level);
	acpigen_emit_word(order);
}

/* Sleep (ms) */
void acpigen_write_sleep(uint64_t sleep_ms)
{
	acpigen_emit_ext_op(SLEEP_OP);
	acpigen_write_integer(sleep_ms);
}

void acpigen_write_store(void)
{
	acpigen_emit_byte(STORE_OP);
}

/* Store (src, dst) */
void acpigen_write_store_ops(uint8_t src, uint8_t dst)
{
	acpigen_write_store();
	acpigen_emit_byte(src);
	acpigen_emit_byte(dst);
}

/* Store (src, "namestr") */
void acpigen_write_store_op_to_namestr(uint8_t src, const char *dst)
{
	acpigen_write_store();
	acpigen_emit_byte(src);
	acpigen_emit_namestring(dst);
}

/* Or (arg1, arg2, res) */
void acpigen_write_or(uint8_t arg1, uint8_t arg2, uint8_t res)
{
	acpigen_emit_byte(OR_OP);
	acpigen_emit_byte(arg1);
	acpigen_emit_byte(arg2);
	acpigen_emit_byte(res);
}

/* Xor (arg1, arg2, res) */
void acpigen_write_xor(uint8_t arg1, uint8_t arg2, uint8_t res)
{
	acpigen_emit_byte(XOR_OP);
	acpigen_emit_byte(arg1);
	acpigen_emit_byte(arg2);
	acpigen_emit_byte(res);
}

/* And (arg1, arg2, res) */
void acpigen_write_and(uint8_t arg1, uint8_t arg2, uint8_t res)
{
	acpigen_emit_byte(AND_OP);
	acpigen_emit_byte(arg1);
	acpigen_emit_byte(arg2);
	acpigen_emit_byte(res);
}

/* Not (arg, res) */
void acpigen_write_not(uint8_t arg, uint8_t res)
{
	acpigen_emit_byte(NOT_OP);
	acpigen_emit_byte(arg);
	acpigen_emit_byte(res);
}

/* Store (str, DEBUG) */
void acpigen_write_debug_string(const char *str)
{
	acpigen_write_store();
	acpigen_write_string(str);
	acpigen_emit_ext_op(DEBUG_OP);
}

/* Store (val, DEBUG) */
void acpigen_write_debug_integer(uint64_t val)
{
	acpigen_write_store();
	acpigen_write_integer(val);
	acpigen_emit_ext_op(DEBUG_OP);
}

/* Store (op, DEBUG) */
void acpigen_write_debug_op(uint8_t op)
{
	acpigen_write_store();
	acpigen_emit_byte(op);
	acpigen_emit_ext_op(DEBUG_OP);
}

void acpigen_write_if(void)
{
	acpigen_emit_byte(IF_OP);
	acpigen_write_len_f();
}

/* If (And (arg1, arg2)) */
void acpigen_write_if_and(uint8_t arg1, uint8_t arg2)
{
	acpigen_write_if();
	acpigen_emit_byte(AND_OP);
	acpigen_emit_byte(arg1);
	acpigen_emit_byte(arg2);
}

/*
 * Generates ACPI code for checking if operand1 and operand2 are equal, where,
 * operand1 is ACPI op and operand2 is an integer.
 *
 * If (Lequal (op, val))
 */
void acpigen_write_if_lequal_op_int(uint8_t op, uint64_t val)
{
	acpigen_write_if();
	acpigen_emit_byte(LEQUAL_OP);
	acpigen_emit_byte(op);
	acpigen_write_integer(val);
}

/*
 * Generates ACPI code for checking if operand1 and operand2 are equal, where,
 * operand1 is namestring and operand2 is an integer.
 *
 * If (Lequal ("namestr", val))
 */
void acpigen_write_if_lequal_namestr_int(const char *namestr, uint64_t val)
{
	acpigen_write_if();
	acpigen_emit_byte(LEQUAL_OP);
	acpigen_emit_namestring(namestr);
	acpigen_write_integer(val);
}

void acpigen_write_else(void)
{
	acpigen_emit_byte(ELSE_OP);
	acpigen_write_len_f();
}

void acpigen_write_to_buffer(uint8_t src, uint8_t dst)
{
	acpigen_emit_byte(TO_BUFFER_OP);
	acpigen_emit_byte(src);
	acpigen_emit_byte(dst);
}

void acpigen_write_to_integer(uint8_t src, uint8_t dst)
{
	acpigen_emit_byte(TO_INTEGER_OP);
	acpigen_emit_byte(src);
	acpigen_emit_byte(dst);
}

void acpigen_write_byte_buffer(uint8_t *arr, size_t size)
{
	size_t i;

	acpigen_emit_byte(BUFFER_OP);
	acpigen_write_len_f();
	acpigen_write_integer(size);

	for (i = 0; i < size; i++)
		acpigen_emit_byte(arr[i]);

	acpigen_pop_len();
}

void acpigen_write_return_byte_buffer(uint8_t *arr, size_t size)
{
	acpigen_emit_byte(RETURN_OP);
	acpigen_write_byte_buffer(arr, size);
}

void acpigen_write_return_singleton_buffer(uint8_t arg)
{
	acpigen_write_return_byte_buffer(&arg, 1);
}

void acpigen_write_return_byte(uint8_t arg)
{
	acpigen_emit_byte(RETURN_OP);
	acpigen_write_byte(arg);
}

void acpigen_write_return_integer(uint64_t arg)
{
	acpigen_emit_byte(RETURN_OP);
	acpigen_write_integer(arg);
}

void acpigen_write_return_string(const char *arg)
{
	acpigen_emit_byte(RETURN_OP);
	acpigen_write_string(arg);
}

void acpigen_write_upc(enum acpi_upc_type type)
{
	acpigen_write_name("_UPC");
	acpigen_write_package(4);
	/* Connectable */
	acpigen_write_byte(type == UPC_TYPE_UNUSED ? 0 : 0xff);
	/* Type */
	acpigen_write_byte(type);
	/* Reserved0 */
	acpigen_write_zero();
	/* Reserved1 */
	acpigen_write_zero();
	acpigen_pop_len();
}

void acpigen_write_pld(const struct acpi_pld *pld)
{
	uint8_t buf[20];

	if (acpi_pld_to_buffer(pld, buf, ARRAY_SIZE(buf)) < 0)
		return;

	acpigen_write_name("_PLD");
	acpigen_write_package(1);
	acpigen_write_byte_buffer(buf, ARRAY_SIZE(buf));
	acpigen_pop_len();
}

void acpigen_write_dsm(const char *uuid, void (**callbacks)(void *),
		       size_t count, void *arg)
{
	struct dsm_uuid id = DSM_UUID(uuid, callbacks, count, arg);
	acpigen_write_dsm_uuid_arr(&id, 1);
}

static void acpigen_write_dsm_uuid(struct dsm_uuid *id)
{
	size_t i;

	/* If (LEqual (Local0, ToUUID(uuid))) */
	acpigen_write_if();
	acpigen_emit_byte(LEQUAL_OP);
	acpigen_emit_byte(LOCAL0_OP);
	acpigen_write_uuid(id->uuid);

	/* ToInteger (Arg2, Local1) */
	acpigen_write_to_integer(ARG2_OP, LOCAL1_OP);

	for (i = 0; i < id->count; i++) {
		/* If (LEqual (Local1, i)) */
		acpigen_write_if_lequal_op_int(LOCAL1_OP, i);

		/* Callback to write if handler. */
		if (id->callbacks[i])
			id->callbacks[i](id->arg);

		acpigen_pop_len();	/* If */
	}

	/* Default case: Return (Buffer (One) { 0x0 }) */
	acpigen_write_return_singleton_buffer(0x0);

	acpigen_pop_len();	/* If (LEqual (Local0, ToUUID(uuid))) */

}

/*
 * Generate ACPI AML code for _DSM method.
 * This function takes as input array of uuid for the device, set of callbacks
 * and argument to pass into the callbacks. Callbacks should ensure that Local0
 * and Local1 are left untouched. Use of Local2-Local7 is permitted in
 * callbacks.
 *
 * Arguments passed into _DSM method:
 * Arg0 = UUID
 * Arg1 = Revision
 * Arg2 = Function index
 * Arg3 = Function specific arguments
 *
 * AML code generated would look like:
 * Method (_DSM, 4, Serialized) {
 *	ToBuffer (Arg0, Local0)
 *	If (LEqual (Local0, ToUUID(uuid))) {
 *		ToInteger (Arg2, Local1)
 *		If (LEqual (Local1, 0)) {
 *			<acpigen by callback[0]>
 *		}
 *		...
 *		If (LEqual (Local1, n)) {
 *			<acpigen by callback[n]>
 *		}
 *		Return (Buffer (One) { 0x0 })
 *	}
 *	...
 *	If (LEqual (Local0, ToUUID(uuidn))) {
 *	...
 *	}
 *	Return (Buffer (One) { 0x0 })
 * }
 */
void acpigen_write_dsm_uuid_arr(struct dsm_uuid *ids, size_t count)
{
	size_t i;

	/* Method (_DSM, 4, Serialized) */
	acpigen_write_method_serialized("_DSM", 0x4);

	/* ToBuffer (Arg0, Local0) */
	acpigen_write_to_buffer(ARG0_OP, LOCAL0_OP);

	for (i = 0; i < count; i++)
		acpigen_write_dsm_uuid(&ids[i]);

	/* Return (Buffer (One) { 0x0 }) */
	acpigen_write_return_singleton_buffer(0x0);

	acpigen_pop_len();	/* Method _DSM */
}

#define CPPC_PACKAGE_NAME "\\GCPC"

void acpigen_write_CPPC_package(const struct cppc_config *config)
{
	u32 i;
	u32 max;
	switch (config->version) {
	case 1:
		max = CPPC_MAX_FIELDS_VER_1;
		break;
	case 2:
		max = CPPC_MAX_FIELDS_VER_2;
		break;
	case 3:
		max = CPPC_MAX_FIELDS_VER_3;
		break;
	default:
		printk(BIOS_ERR, "ERROR: CPPC version %u is not implemented\n",
		       config->version);
		return;
	}
	acpigen_write_name(CPPC_PACKAGE_NAME);

	/* Adding 2 to account for length and version fields */
	acpigen_write_package(max + 2);
	acpigen_write_dword(max + 2);

	acpigen_write_byte(config->version);

	for (i = 0; i < max; ++i) {
		const acpi_addr_t *reg = &(config->regs[i]);
		if (reg->space_id == ACPI_ADDRESS_SPACE_MEMORY &&
		    reg->bit_width == 32 && reg->access_size == 0) {
			acpigen_write_dword(reg->addrl);
		} else {
			acpigen_write_register_resource(reg);
		}
	}
	acpigen_pop_len();
}

void acpigen_write_CPPC_method(void)
{
	acpigen_write_method("_CPC", 0);
	acpigen_emit_byte(RETURN_OP);
	acpigen_emit_namestring(CPPC_PACKAGE_NAME);
	acpigen_pop_len();
}

/*
 * Generate ACPI AML code for _ROM method.
 * This function takes as input ROM data and ROM length.
 *
 * The ACPI spec isn't clear about what should happen at the end of the
 * ROM. Tests showed that it shouldn't truncate, but fill the remaining
 * bytes in the returned buffer with zeros.
 *
 * Arguments passed into _DSM method:
 * Arg0 = Offset in Bytes
 * Arg1 = Bytes to return
 *
 * Example:
 *   acpigen_write_rom(0xdeadbeef, 0x10000)
 *
 * AML code generated would look like:
 * Method (_ROM, 2, NotSerialized) {
 *
 *	OperationRegion("ROMS", SYSTEMMEMORY, 0xdeadbeef, 0x10000)
 *	Field (ROMS, AnyAcc, NoLock, Preserve)
 *	{
 *		Offset (0),
 *		RBF0,   0x80000
 *	}
 *
 *	Store (Arg0, Local0)
 *	Store (Arg1, Local1)
 *
 *	If (LGreater (Local1, 0x1000))
 *	{
 *		Store (0x1000, Local1)
 *	}
 *
 *	Store (Local1, Local3)
 *
 *	If (LGreater (Local0, 0x10000))
 *	{
 *		Return(Buffer(Local1){0})
 *	}
 *
 *	If (LGreater (Local0, 0x0f000))
 *	{
 *		Subtract (0x10000, Local0, Local2)
 *		If (LGreater (Local1, Local2))
 *		{
 *			Store (Local2, Local1)
 *		}
 *	}
 *
 *	Name (ROM1, Buffer (Local3) {0})
 *
 *	Multiply (Local0, 0x08, Local0)
 *	Multiply (Local1, 0x08, Local1)
 *
 *	CreateField (RBF0, Local0, Local1, TMPB)
 *	Store (TMPB, ROM1)
 *	Return (ROM1)
 * }
 */

void acpigen_write_rom(void *bios, const size_t length)
{
	ASSERT(bios)
	ASSERT(length)

	/* Method (_ROM, 2, Serialized) */
	acpigen_write_method_serialized("_ROM", 2);

	/* OperationRegion("ROMS", SYSTEMMEMORY, current, length) */
	struct opregion opreg = OPREGION("ROMS", SYSTEMMEMORY,
			(uintptr_t)bios, length);
	acpigen_write_opregion(&opreg);

	struct fieldlist l[] = {
		FIELDLIST_OFFSET(0),
		FIELDLIST_NAMESTR("RBF0", 8 * length),
	};

	/* Field (ROMS, AnyAcc, NoLock, Preserve)
	 * {
	 *  Offset (0),
	 *  RBF0,   0x80000
	 * } */
	acpigen_write_field(opreg.name, l, 2, FIELD_ANYACC |
			    FIELD_NOLOCK | FIELD_PRESERVE);

	/* Store (Arg0, Local0) */
	acpigen_write_store();
	acpigen_emit_byte(ARG0_OP);
	acpigen_emit_byte(LOCAL0_OP);

	/* Store (Arg1, Local1) */
	acpigen_write_store();
	acpigen_emit_byte(ARG1_OP);
	acpigen_emit_byte(LOCAL1_OP);

	/* ACPI SPEC requires to return at maximum 4KiB */
	/* If (LGreater (Local1, 0x1000)) */
	acpigen_write_if();
	acpigen_emit_byte(LGREATER_OP);
	acpigen_emit_byte(LOCAL1_OP);
	acpigen_write_integer(0x1000);

	/* Store (0x1000, Local1) */
	acpigen_write_store();
	acpigen_write_integer(0x1000);
	acpigen_emit_byte(LOCAL1_OP);

	/* Pop if */
	acpigen_pop_len();

	/* Store (Local1, Local3) */
	acpigen_write_store();
	acpigen_emit_byte(LOCAL1_OP);
	acpigen_emit_byte(LOCAL3_OP);

	/* If (LGreater (Local0, length)) */
	acpigen_write_if();
	acpigen_emit_byte(LGREATER_OP);
	acpigen_emit_byte(LOCAL0_OP);
	acpigen_write_integer(length);

	/* Return(Buffer(Local1){0}) */
	acpigen_emit_byte(RETURN_OP);
	acpigen_emit_byte(BUFFER_OP);
	acpigen_write_len_f();
	acpigen_emit_byte(LOCAL1_OP);
	acpigen_emit_byte(0);
	acpigen_pop_len();

	/* Pop if */
	acpigen_pop_len();

	/* If (LGreater (Local0, length - 4096)) */
	acpigen_write_if();
	acpigen_emit_byte(LGREATER_OP);
	acpigen_emit_byte(LOCAL0_OP);
	acpigen_write_integer(length - 4096);

	/* Subtract (length, Local0, Local2) */
	acpigen_emit_byte(SUBTRACT_OP);
	acpigen_write_integer(length);
	acpigen_emit_byte(LOCAL0_OP);
	acpigen_emit_byte(LOCAL2_OP);

	/* If (LGreater (Local1, Local2)) */
	acpigen_write_if();
	acpigen_emit_byte(LGREATER_OP);
	acpigen_emit_byte(LOCAL1_OP);
	acpigen_emit_byte(LOCAL2_OP);

	/* Store (Local2, Local1) */
	acpigen_write_store();
	acpigen_emit_byte(LOCAL2_OP);
	acpigen_emit_byte(LOCAL1_OP);

	/* Pop if */
	acpigen_pop_len();

	/* Pop if */
	acpigen_pop_len();

	/* Name (ROM1, Buffer (Local3) {0}) */
	acpigen_write_name("ROM1");
	acpigen_emit_byte(BUFFER_OP);
	acpigen_write_len_f();
	acpigen_emit_byte(LOCAL3_OP);
	acpigen_emit_byte(0);
	acpigen_pop_len();

	/* Multiply (Local1, 0x08, Local1) */
	acpigen_emit_byte(MULTIPLY_OP);
	acpigen_emit_byte(LOCAL1_OP);
	acpigen_write_integer(0x08);
	acpigen_emit_byte(LOCAL1_OP);

	/* Multiply (Local0, 0x08, Local0) */
	acpigen_emit_byte(MULTIPLY_OP);
	acpigen_emit_byte(LOCAL0_OP);
	acpigen_write_integer(0x08);
	acpigen_emit_byte(LOCAL0_OP);

	/* CreateField (RBF0, Local0, Local1, TMPB) */
	acpigen_emit_ext_op(CREATEFIELD_OP);
	acpigen_emit_namestring("RBF0");
	acpigen_emit_byte(LOCAL0_OP);
	acpigen_emit_byte(LOCAL1_OP);
	acpigen_emit_namestring("TMPB");

	/* Store (TMPB, ROM1) */
	acpigen_write_store();
	acpigen_emit_namestring("TMPB");
	acpigen_emit_namestring("ROM1");

	/* Return (ROM1) */
	acpigen_emit_byte(RETURN_OP);
	acpigen_emit_namestring("ROM1");

	/* Pop method */
	acpigen_pop_len();
}


/* Soc-implemented functions -- weak definitions. */
int __weak acpigen_soc_read_rx_gpio(unsigned int gpio_num)
{
	printk(BIOS_ERR, "ERROR: %s not implemented\n", __func__);
	acpigen_write_debug_string("read_rx_gpio not available");
	return -1;
}

int __weak acpigen_soc_get_tx_gpio(unsigned int gpio_num)
{
	printk(BIOS_ERR, "ERROR: %s not implemented\n", __func__);
	acpigen_write_debug_string("get_tx_gpio not available");
	return -1;
}

int __weak acpigen_soc_set_tx_gpio(unsigned int gpio_num)
{
	printk(BIOS_ERR, "ERROR: %s not implemented\n", __func__);
	acpigen_write_debug_string("set_tx_gpio not available");
	return -1;
}

int __weak acpigen_soc_clear_tx_gpio(unsigned int gpio_num)
{
	printk(BIOS_ERR, "ERROR: %s not implemented\n", __func__);
	acpigen_write_debug_string("clear_tx_gpio not available");
	return -1;
}

/*
 * Helper functions for enabling/disabling Tx GPIOs based on the GPIO
 * polarity. These functions end up calling acpigen_soc_{set,clear}_tx_gpio to
 * make callbacks into SoC acpigen code.
 *
 * Returns 0 on success and -1 on error.
 */
int acpigen_enable_tx_gpio(struct acpi_gpio *gpio)
{
	if (gpio->polarity == ACPI_GPIO_ACTIVE_HIGH)
		return acpigen_soc_set_tx_gpio(gpio->pins[0]);
	else
		return acpigen_soc_clear_tx_gpio(gpio->pins[0]);
}

int acpigen_disable_tx_gpio(struct acpi_gpio *gpio)
{
	if (gpio->polarity == ACPI_GPIO_ACTIVE_LOW)
		return acpigen_soc_set_tx_gpio(gpio->pins[0]);
	else
		return acpigen_soc_clear_tx_gpio(gpio->pins[0]);
}

void acpigen_get_rx_gpio(struct acpi_gpio *gpio)
{
	acpigen_soc_read_rx_gpio(gpio->pins[0]);

	if (gpio->polarity == ACPI_GPIO_ACTIVE_LOW)
		acpigen_write_xor(LOCAL0_OP, 1, LOCAL0_OP);
}

/* refer to ACPI 6.4.3.5.3 Word Address Space Descriptor section for details */
void acpigen_resource_word(u16 res_type, u16 gen_flags, u16 type_flags, u16 gran,
	u16 range_min, u16 range_max, u16 translation, u16 length)
{
	acpigen_emit_byte(0x88);
	/* Byte 1+2: length (0x000d) */
	acpigen_emit_byte(0x0d);
	acpigen_emit_byte(0x00);
	/* resource type */
	acpigen_emit_byte(res_type); // 0 - mem, 1 - io, 2 - bus
	/* general flags */
	acpigen_emit_byte(gen_flags);
	/* type flags */
	// refer to ACPI Table 6-234 (Memory), 6-235 (IO), 6-236 (Bus) for details
	acpigen_emit_byte(type_flags);
	/* granularity, min, max, translation, length */
	acpigen_emit_word(gran);
	acpigen_emit_word(range_min);
	acpigen_emit_word(range_max);
	acpigen_emit_word(translation);
	acpigen_emit_word(length);
}

/* refer to ACPI 6.4.3.5.2 DWord Address Space Descriptor section for details */
void acpigen_resource_dword(u16 res_type, u16 gen_flags, u16 type_flags,
	u32 gran, u32 range_min, u32 range_max, u32 translation, u32 length)
{
	acpigen_emit_byte(0x87);
	/* Byte 1+2: length (0023) */
	acpigen_emit_byte(23);
	acpigen_emit_byte(0x00);
	/* resource type */
	acpigen_emit_byte(res_type); // 0 - mem, 1 - io, 2 - bus
	/* general flags */
	acpigen_emit_byte(gen_flags);
	/* type flags */
	// refer to ACPI Table 6-234 (Memory), 6-235 (IO), 6-236 (Bus) for details
	acpigen_emit_byte(type_flags);
	/* granularity, min, max, translation, length */
	acpigen_emit_dword(gran);
	acpigen_emit_dword(range_min);
	acpigen_emit_dword(range_max);
	acpigen_emit_dword(translation);
	acpigen_emit_dword(length);
}

static void acpigen_emit_qword(u64 data)
{
	acpigen_emit_dword(data & 0xffffffff);
	acpigen_emit_dword((data >> 32) & 0xffffffff);
}

/* refer to ACPI 6.4.3.5.1 QWord Address Space Descriptor section for details */
void acpigen_resource_qword(u16 res_type, u16 gen_flags, u16 type_flags,
	u64 gran, u64 range_min, u64 range_max, u64 translation, u64 length)
{
	acpigen_emit_byte(0x8a);
	/* Byte 1+2: length (0x002b) */
	acpigen_emit_byte(0x2b);
	acpigen_emit_byte(0x00);
	/* resource type */
	acpigen_emit_byte(res_type); // 0 - mem, 1 - io, 2 - bus
	/* general flags */
	acpigen_emit_byte(gen_flags);
	/* type flags */
	// refer to ACPI Table 6-234 (Memory), 6-235 (IO), 6-236 (Bus) for details
	acpigen_emit_byte(type_flags);
	/* granularity, min, max, translation, length */
	acpigen_emit_qword(gran);
	acpigen_emit_qword(range_min);
	acpigen_emit_qword(range_max);
	acpigen_emit_qword(translation);
	acpigen_emit_qword(length);
}

void acpigen_write_ADR(uint64_t adr)
{
	acpigen_write_name_qword("_ADR", adr);
}

void acpigen_write_ADR_pci_devfn(pci_devfn_t devfn)
{
	/*
	 * _ADR for PCI Bus is encoded as follows:
	 * [63:32] - unused
	 * [31:16] - device #
	 * [15:0]  - function #
	 */
	acpigen_write_ADR(PCI_SLOT(devfn) << 16 | PCI_FUNC(devfn));
}

void acpigen_write_ADR_pci_device(const struct device *dev)
{
	assert(dev->path.type == DEVICE_PATH_PCI);
	acpigen_write_ADR_pci_devfn(dev->path.pci.devfn);
}