Merge branch 'for-6.7/cxl-qtg' into cxl/next

Merge some prep-work for CXL QOS class support. This cycle saw large
collisions with mm on this topic, so the bulk of this topic needs to
wait.

Documentation/ABI/testing/sysfs-bus-cxl

@@ -369,6 +369,21 @@ Description:
 		provided it is currently idle / not bound to a driver.
 
 
+What:		/sys/bus/cxl/devices/decoderX.Y/qos_class
+Date:		May, 2023
+KernelVersion:	v6.5
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(RO) For CXL host platforms that support "QoS Telemmetry" this
+		root-decoder-only attribute conveys a platform specific cookie
+		that identifies a QoS performance class for the CXL Window.
+		This class-id can be compared against a similar "qos_class"
+		published for each memory-type that an endpoint supports. While
+		it is not required that endpoints map their local memory-class
+		to a matching platform class, mismatches are not recommended and
+		there are platform specific side-effects that may result.
+
+
 What:		/sys/bus/cxl/devices/regionZ/uuid
 Date:		May, 2022
 KernelVersion:	v6.0

MAINTAINERS

@@ -294,6 +294,8 @@ F:	drivers/pnp/pnpacpi/
 F:	include/acpi/
 F:	include/linux/acpi.h
 F:	include/linux/fwnode.h
+F:	include/linux/fw_table.h
+F:	lib/fw_table.c
 F:	tools/power/acpi/
 
 ACPI APEI

drivers/acpi/Kconfig

@@ -12,6 +12,7 @@ menuconfig ACPI
 	select PNP
 	select NLS
 	select CRC32
+	select FIRMWARE_TABLE
 	default y if X86
 	help
 	  Advanced Configuration and Power Interface (ACPI) support for 

drivers/acpi/tables.c

@@ -37,18 +37,6 @@ static struct acpi_table_desc initial_tables[ACPI_MAX_TABLES] __initdata;
 
 static int acpi_apic_instance __initdata_or_acpilib;
 
-enum acpi_subtable_type {
-	ACPI_SUBTABLE_COMMON,
-	ACPI_SUBTABLE_HMAT,
-	ACPI_SUBTABLE_PRMT,
-	ACPI_SUBTABLE_CEDT,
-};
-
-struct acpi_subtable_entry {
-	union acpi_subtable_headers *hdr;
-	enum acpi_subtable_type type;
-};
-
 /*
  * Disable table checksum verification for the early stage due to the size
  * limitation of the current x86 early mapping implementation.
@@ -237,167 +225,6 @@ void acpi_table_print_madt_entry(struct acpi_subtable_header *header)
 	}
 }
 
-static unsigned long __init_or_acpilib
-acpi_get_entry_type(struct acpi_subtable_entry *entry)
-{
-	switch (entry->type) {
-	case ACPI_SUBTABLE_COMMON:
-		return entry->hdr->common.type;
-	case ACPI_SUBTABLE_HMAT:
-		return entry->hdr->hmat.type;
-	case ACPI_SUBTABLE_PRMT:
-		return 0;
-	case ACPI_SUBTABLE_CEDT:
-		return entry->hdr->cedt.type;
-	}
-	return 0;
-}
-
-static unsigned long __init_or_acpilib
-acpi_get_entry_length(struct acpi_subtable_entry *entry)
-{
-	switch (entry->type) {
-	case ACPI_SUBTABLE_COMMON:
-		return entry->hdr->common.length;
-	case ACPI_SUBTABLE_HMAT:
-		return entry->hdr->hmat.length;
-	case ACPI_SUBTABLE_PRMT:
-		return entry->hdr->prmt.length;
-	case ACPI_SUBTABLE_CEDT:
-		return entry->hdr->cedt.length;
-	}
-	return 0;
-}
-
-static unsigned long __init_or_acpilib
-acpi_get_subtable_header_length(struct acpi_subtable_entry *entry)
-{
-	switch (entry->type) {
-	case ACPI_SUBTABLE_COMMON:
-		return sizeof(entry->hdr->common);
-	case ACPI_SUBTABLE_HMAT:
-		return sizeof(entry->hdr->hmat);
-	case ACPI_SUBTABLE_PRMT:
-		return sizeof(entry->hdr->prmt);
-	case ACPI_SUBTABLE_CEDT:
-		return sizeof(entry->hdr->cedt);
-	}
-	return 0;
-}
-
-static enum acpi_subtable_type __init_or_acpilib
-acpi_get_subtable_type(char *id)
-{
-	if (strncmp(id, ACPI_SIG_HMAT, 4) == 0)
-		return ACPI_SUBTABLE_HMAT;
-	if (strncmp(id, ACPI_SIG_PRMT, 4) == 0)
-		return ACPI_SUBTABLE_PRMT;
-	if (strncmp(id, ACPI_SIG_CEDT, 4) == 0)
-		return ACPI_SUBTABLE_CEDT;
-	return ACPI_SUBTABLE_COMMON;
-}
-
-static __init_or_acpilib bool has_handler(struct acpi_subtable_proc *proc)
-{
-	return proc->handler || proc->handler_arg;
-}
-
-static __init_or_acpilib int call_handler(struct acpi_subtable_proc *proc,
-					  union acpi_subtable_headers *hdr,
-					  unsigned long end)
-{
-	if (proc->handler)
-		return proc->handler(hdr, end);
-	if (proc->handler_arg)
-		return proc->handler_arg(hdr, proc->arg, end);
-	return -EINVAL;
-}
-
-/**
- * acpi_parse_entries_array - for each proc_num find a suitable subtable
- *
- * @id: table id (for debugging purposes)
- * @table_size: size of the root table
- * @table_header: where does the table start?
- * @proc: array of acpi_subtable_proc struct containing entry id
- *        and associated handler with it
- * @proc_num: how big proc is?
- * @max_entries: how many entries can we process?
- *
- * For each proc_num find a subtable with proc->id and run proc->handler
- * on it. Assumption is that there's only single handler for particular
- * entry id.
- *
- * The table_size is not the size of the complete ACPI table (the length
- * field in the header struct), but only the size of the root table; i.e.,
- * the offset from the very first byte of the complete ACPI table, to the
- * first byte of the very first subtable.
- *
- * On success returns sum of all matching entries for all proc handlers.
- * Otherwise, -ENODEV or -EINVAL is returned.
- */
-static int __init_or_acpilib acpi_parse_entries_array(
-	char *id, unsigned long table_size,
-	struct acpi_table_header *table_header, struct acpi_subtable_proc *proc,
-	int proc_num, unsigned int max_entries)
-{
-	struct acpi_subtable_entry entry;
-	unsigned long table_end, subtable_len, entry_len;
-	int count = 0;
-	int errs = 0;
-	int i;
-
-	table_end = (unsigned long)table_header + table_header->length;
-
-	/* Parse all entries looking for a match. */
-
-	entry.type = acpi_get_subtable_type(id);
-	entry.hdr = (union acpi_subtable_headers *)
-	    ((unsigned long)table_header + table_size);
-	subtable_len = acpi_get_subtable_header_length(&entry);
-
-	while (((unsigned long)entry.hdr) + subtable_len  < table_end) {
-		if (max_entries && count >= max_entries)
-			break;
-
-		for (i = 0; i < proc_num; i++) {
-			if (acpi_get_entry_type(&entry) != proc[i].id)
-				continue;
-			if (!has_handler(&proc[i]) ||
-			    (!errs &&
-			     call_handler(&proc[i], entry.hdr, table_end))) {
-				errs++;
-				continue;
-			}
-
-			proc[i].count++;
-			break;
-		}
-		if (i != proc_num)
-			count++;
-
-		/*
-		 * If entry->length is 0, break from this loop to avoid
-		 * infinite loop.
-		 */
-		entry_len = acpi_get_entry_length(&entry);
-		if (entry_len == 0) {
-			pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id);
-			return -EINVAL;
-		}
-
-		entry.hdr = (union acpi_subtable_headers *)
-		    ((unsigned long)entry.hdr + entry_len);
-	}
-
-	if (max_entries && count > max_entries) {
-		pr_warn("[%4.4s:0x%02x] found the maximum %i entries\n",
-			id, proc->id, count);
-	}
-
-	return errs ? -EINVAL : count;
-}
-
 int __init_or_acpilib acpi_table_parse_entries_array(
 	char *id, unsigned long table_size, struct acpi_subtable_proc *proc,
 	int proc_num, unsigned int max_entries)

drivers/cxl/acpi.c

@@ -289,6 +289,9 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
 			}
 		}
 	}
+
+	cxlrd->qos_class = cfmws->qtg_id;
+
 	rc = cxl_decoder_add(cxld, target_map);
 err_xormap:
 	if (rc)

drivers/cxl/core/pci.c

@@ -596,6 +596,16 @@ static int cxl_cdat_read_table(struct device *dev,
 	return 0;
 }
 
+static unsigned char cdat_checksum(void *buf, size_t size)
+{
+	unsigned char sum, *data = buf;
+	size_t i;
+
+	for (sum = 0, i = 0; i < size; i++)
+		sum += data[i];
+	return sum;
+}
+
 /**
  * read_cdat_data - Read the CDAT data on this port
  * @port: Port to read data from
@@ -604,18 +614,30 @@ static int cxl_cdat_read_table(struct device *dev,
  */
 void read_cdat_data(struct cxl_port *port)
 {
-	struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport_dev);
-	struct device *host = cxlmd->dev.parent;
+	struct device *uport = port->uport_dev;
 	struct device *dev = &port->dev;
 	struct pci_doe_mb *cdat_doe;
+	struct pci_dev *pdev = NULL;
+	struct cxl_memdev *cxlmd;
 	size_t cdat_length;
 	void *cdat_table;
 	int rc;
 
-	if (!dev_is_pci(host))
+	if (is_cxl_memdev(uport)) {
+		struct device *host;
+
+		cxlmd = to_cxl_memdev(uport);
+		host = cxlmd->dev.parent;
+		if (dev_is_pci(host))
+			pdev = to_pci_dev(host);
+	} else if (dev_is_pci(uport)) {
+		pdev = to_pci_dev(uport);
+	}
+
+	if (!pdev)
 		return;
-	cdat_doe = pci_find_doe_mailbox(to_pci_dev(host),
-					PCI_DVSEC_VENDOR_ID_CXL,
+
+	cdat_doe = pci_find_doe_mailbox(pdev, PCI_DVSEC_VENDOR_ID_CXL,
 					CXL_DOE_PROTOCOL_TABLE_ACCESS);
 	if (!cdat_doe) {
 		dev_dbg(dev, "No CDAT mailbox\n");
@@ -635,15 +657,21 @@ void read_cdat_data(struct cxl_port *port)
 		return;
 
 	rc = cxl_cdat_read_table(dev, cdat_doe, cdat_table, &cdat_length);
-	if (rc) {
-		/* Don't leave table data allocated on error */
-		devm_kfree(dev, cdat_table);
-		dev_err(dev, "CDAT data read error\n");
-		return;
-	}
+	if (rc)
+		goto err;
+
+	cdat_table = cdat_table + sizeof(__le32);
+	if (cdat_checksum(cdat_table, cdat_length))
+		goto err;
 
-	port->cdat.table = cdat_table + sizeof(__le32);
+	port->cdat.table = cdat_table;
 	port->cdat.length = cdat_length;
+	return;
+
+err:
+	/* Don't leave table data allocated on error */
+	devm_kfree(dev, cdat_table);
+	dev_err(dev, "Failed to read/validate CDAT.\n");
 }
 EXPORT_SYMBOL_NS_GPL(read_cdat_data, CXL);
 

drivers/cxl/core/port.c

@@ -284,6 +284,15 @@ static ssize_t interleave_ways_show(struct device *dev,
 
 static DEVICE_ATTR_RO(interleave_ways);
 
+static ssize_t qos_class_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);
+
+	return sysfs_emit(buf, "%d\n", cxlrd->qos_class);
+}
+static DEVICE_ATTR_RO(qos_class);
+
 static struct attribute *cxl_decoder_base_attrs[] = {
 	&dev_attr_start.attr,
 	&dev_attr_size.attr,
@@ -303,6 +312,7 @@ static struct attribute *cxl_decoder_root_attrs[] = {
 	&dev_attr_cap_type2.attr,
 	&dev_attr_cap_type3.attr,
 	&dev_attr_target_list.attr,
+	&dev_attr_qos_class.attr,
 	SET_CXL_REGION_ATTR(create_pmem_region)
 	SET_CXL_REGION_ATTR(create_ram_region)
 	SET_CXL_REGION_ATTR(delete_region)
@@ -1735,6 +1745,7 @@ struct cxl_root_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
 	}
 
 	atomic_set(&cxlrd->region_id, rc);
+	cxlrd->qos_class = CXL_QOS_CLASS_INVALID;
 	return cxlrd;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_root_decoder_alloc, CXL);

drivers/cxl/cxl.h

@@ -328,6 +328,7 @@ enum cxl_decoder_type {
  */
 #define CXL_DECODER_MAX_INTERLEAVE 16
 
+#define CXL_QOS_CLASS_INVALID -1
 
 /**
  * struct cxl_decoder - Common CXL HDM Decoder Attributes
@@ -439,6 +440,7 @@ typedef struct cxl_dport *(*cxl_calc_hb_fn)(struct cxl_root_decoder *cxlrd,
  * @calc_hb: which host bridge covers the n'th position by granularity
  * @platform_data: platform specific configuration data
  * @range_lock: sync region autodiscovery by address range
+ * @qos_class: QoS performance class cookie
  * @cxlsd: base cxl switch decoder
  */
 struct cxl_root_decoder {
@@ -447,6 +449,7 @@ struct cxl_root_decoder {
 	cxl_calc_hb_fn calc_hb;
 	void *platform_data;
 	struct mutex range_lock;
+	int qos_class;
 	struct cxl_switch_decoder cxlsd;
 };
 

drivers/cxl/port.c

@@ -62,6 +62,9 @@ static int cxl_switch_port_probe(struct cxl_port *port)
 	struct cxl_hdm *cxlhdm;
 	int rc;
 
+	/* Cache the data early to ensure is_visible() works */
+	read_cdat_data(port);
+
 	rc = devm_cxl_port_enumerate_dports(port);
 	if (rc < 0)
 		return rc;

include/acpi/actbl1.h

@@ -465,6 +465,9 @@ struct acpi_cdat_sslbe {
 	u16 reserved;
 };
 
+#define ACPI_CDAT_SSLBIS_US_PORT	0x0100
+#define ACPI_CDAT_SSLBIS_ANY_PORT	0xffff
+
 /*******************************************************************************
  *
  * CEDT - CXL Early Discovery Table

include/linux/acpi.h

@@ -15,6 +15,7 @@
 #include <linux/mod_devicetable.h>
 #include <linux/property.h>
 #include <linux/uuid.h>
+#include <linux/fw_table.h>
 
 struct irq_domain;
 struct irq_domain_ops;
@@ -24,6 +25,16 @@ struct irq_domain_ops;
 #endif
 #include <acpi/acpi.h>
 
+#ifdef CONFIG_ACPI_TABLE_LIB
+#define EXPORT_SYMBOL_ACPI_LIB(x) EXPORT_SYMBOL_NS_GPL(x, ACPI)
+#define __init_or_acpilib
+#define __initdata_or_acpilib
+#else
+#define EXPORT_SYMBOL_ACPI_LIB(x)
+#define __init_or_acpilib __init
+#define __initdata_or_acpilib __initdata
+#endif
+
 #ifdef	CONFIG_ACPI
 
 #include <linux/list.h>
@@ -119,21 +130,8 @@ enum acpi_address_range_id {
 
 
 /* Table Handlers */
-union acpi_subtable_headers {
-	struct acpi_subtable_header common;
-	struct acpi_hmat_structure hmat;
-	struct acpi_prmt_module_header prmt;
-	struct acpi_cedt_header cedt;
-};
-
 typedef int (*acpi_tbl_table_handler)(struct acpi_table_header *table);
 
-typedef int (*acpi_tbl_entry_handler)(union acpi_subtable_headers *header,
-				      const unsigned long end);
-
-typedef int (*acpi_tbl_entry_handler_arg)(union acpi_subtable_headers *header,
-					  void *arg, const unsigned long end);
-
 /* Debugger support */
 
 struct acpi_debugger_ops {
@@ -207,14 +205,6 @@ static inline int acpi_debugger_notify_command_complete(void)
 		(!entry) || (unsigned long)entry + sizeof(*entry) > end ||  \
 		((struct acpi_subtable_header *)entry)->length < sizeof(*entry))
 
-struct acpi_subtable_proc {
-	int id;
-	acpi_tbl_entry_handler handler;
-	acpi_tbl_entry_handler_arg handler_arg;
-	void *arg;
-	int count;
-};
-
 void __iomem *__acpi_map_table(unsigned long phys, unsigned long size);
 void __acpi_unmap_table(void __iomem *map, unsigned long size);
 int early_acpi_boot_init(void);
@@ -229,16 +219,6 @@ void acpi_reserve_initial_tables (void);
 void acpi_table_init_complete (void);
 int acpi_table_init (void);
 
-#ifdef CONFIG_ACPI_TABLE_LIB
-#define EXPORT_SYMBOL_ACPI_LIB(x) EXPORT_SYMBOL_NS_GPL(x, ACPI)
-#define __init_or_acpilib
-#define __initdata_or_acpilib
-#else
-#define EXPORT_SYMBOL_ACPI_LIB(x)
-#define __init_or_acpilib __init
-#define __initdata_or_acpilib __initdata
-#endif
-
 int acpi_table_parse(char *id, acpi_tbl_table_handler handler);
 int __init_or_acpilib acpi_table_parse_entries(char *id,
 		unsigned long table_size, int entry_id,

include/linux/fw_table.h

+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *  fw_tables.h - Parsing support for ACPI and ACPI-like tables provided by
+ *                platform or device firmware
+ *
+ *  Copyright (C) 2001 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
+ *  Copyright (C) 2023 Intel Corp.
+ */
+#ifndef _FW_TABLE_H_
+#define _FW_TABLE_H_
+
+union acpi_subtable_headers;
+
+typedef int (*acpi_tbl_entry_handler)(union acpi_subtable_headers *header,
+				      const unsigned long end);
+
+typedef int (*acpi_tbl_entry_handler_arg)(union acpi_subtable_headers *header,
+					  void *arg, const unsigned long end);
+
+struct acpi_subtable_proc {
+	int id;
+	acpi_tbl_entry_handler handler;
+	acpi_tbl_entry_handler_arg handler_arg;
+	void *arg;
+	int count;
+};
+
+#include <linux/acpi.h>
+#include <acpi/acpi.h>
+
+union acpi_subtable_headers {
+	struct acpi_subtable_header common;
+	struct acpi_hmat_structure hmat;
+	struct acpi_prmt_module_header prmt;
+	struct acpi_cedt_header cedt;
+};
+
+int acpi_parse_entries_array(char *id, unsigned long table_size,
+			     struct acpi_table_header *table_header,
+			     struct acpi_subtable_proc *proc,
+			     int proc_num, unsigned int max_entries);
+
+#endif

lib/Kconfig

@@ -764,3 +764,6 @@ config ASN1_ENCODER
 
 config POLYNOMIAL
        tristate
+
+config FIRMWARE_TABLE
+	bool

lib/Makefile

@@ -405,6 +405,8 @@ obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_kunit.o
 
 obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o
 
+obj-$(CONFIG_FIRMWARE_TABLE) += fw_table.o
+
 # FORTIFY_SOURCE compile-time behavior tests
 TEST_FORTIFY_SRCS = $(wildcard $(srctree)/$(src)/test_fortify/*-*.c)
 TEST_FORTIFY_LOGS = $(patsubst $(srctree)/$(src)/%.c, %.log, $(TEST_FORTIFY_SRCS))

lib/fw_table.c

+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  fw_tables.c - Parsing support for ACPI and ACPI-like tables provided by
+ *                platform or device firmware
+ *
+ *  Copyright (C) 2001 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
+ *  Copyright (C) 2023 Intel Corp.
+ */
+#include <linux/errno.h>
+#include <linux/fw_table.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+enum acpi_subtable_type {
+	ACPI_SUBTABLE_COMMON,
+	ACPI_SUBTABLE_HMAT,
+	ACPI_SUBTABLE_PRMT,
+	ACPI_SUBTABLE_CEDT,
+};
+
+struct acpi_subtable_entry {
+	union acpi_subtable_headers *hdr;
+	enum acpi_subtable_type type;
+};
+
+static unsigned long __init_or_acpilib
+acpi_get_entry_type(struct acpi_subtable_entry *entry)
+{
+	switch (entry->type) {
+	case ACPI_SUBTABLE_COMMON:
+		return entry->hdr->common.type;
+	case ACPI_SUBTABLE_HMAT:
+		return entry->hdr->hmat.type;
+	case ACPI_SUBTABLE_PRMT:
+		return 0;
+	case ACPI_SUBTABLE_CEDT:
+		return entry->hdr->cedt.type;
+	}
+	return 0;
+}
+
+static unsigned long __init_or_acpilib
+acpi_get_entry_length(struct acpi_subtable_entry *entry)
+{
+	switch (entry->type) {
+	case ACPI_SUBTABLE_COMMON:
+		return entry->hdr->common.length;
+	case ACPI_SUBTABLE_HMAT:
+		return entry->hdr->hmat.length;
+	case ACPI_SUBTABLE_PRMT:
+		return entry->hdr->prmt.length;
+	case ACPI_SUBTABLE_CEDT:
+		return entry->hdr->cedt.length;
+	}
+	return 0;
+}
+
+static unsigned long __init_or_acpilib
+acpi_get_subtable_header_length(struct acpi_subtable_entry *entry)
+{
+	switch (entry->type) {
+	case ACPI_SUBTABLE_COMMON:
+		return sizeof(entry->hdr->common);
+	case ACPI_SUBTABLE_HMAT:
+		return sizeof(entry->hdr->hmat);
+	case ACPI_SUBTABLE_PRMT:
+		return sizeof(entry->hdr->prmt);
+	case ACPI_SUBTABLE_CEDT:
+		return sizeof(entry->hdr->cedt);
+	}
+	return 0;
+}
+
+static enum acpi_subtable_type __init_or_acpilib
+acpi_get_subtable_type(char *id)
+{
+	if (strncmp(id, ACPI_SIG_HMAT, 4) == 0)
+		return ACPI_SUBTABLE_HMAT;
+	if (strncmp(id, ACPI_SIG_PRMT, 4) == 0)
+		return ACPI_SUBTABLE_PRMT;
+	if (strncmp(id, ACPI_SIG_CEDT, 4) == 0)
+		return ACPI_SUBTABLE_CEDT;
+	return ACPI_SUBTABLE_COMMON;
+}
+
+static __init_or_acpilib bool has_handler(struct acpi_subtable_proc *proc)
+{
+	return proc->handler || proc->handler_arg;
+}
+
+static __init_or_acpilib int call_handler(struct acpi_subtable_proc *proc,
+					  union acpi_subtable_headers *hdr,
+					  unsigned long end)
+{
+	if (proc->handler)
+		return proc->handler(hdr, end);
+	if (proc->handler_arg)
+		return proc->handler_arg(hdr, proc->arg, end);
+	return -EINVAL;
+}
+
+/**
+ * acpi_parse_entries_array - for each proc_num find a suitable subtable
+ *
+ * @id: table id (for debugging purposes)
+ * @table_size: size of the root table
+ * @table_header: where does the table start?
+ * @proc: array of acpi_subtable_proc struct containing entry id
+ *        and associated handler with it
+ * @proc_num: how big proc is?
+ * @max_entries: how many entries can we process?
+ *
+ * For each proc_num find a subtable with proc->id and run proc->handler
+ * on it. Assumption is that there's only single handler for particular
+ * entry id.
+ *
+ * The table_size is not the size of the complete ACPI table (the length
+ * field in the header struct), but only the size of the root table; i.e.,
+ * the offset from the very first byte of the complete ACPI table, to the
+ * first byte of the very first subtable.
+ *
+ * On success returns sum of all matching entries for all proc handlers.
+ * Otherwise, -ENODEV or -EINVAL is returned.
+ */
+int __init_or_acpilib
+acpi_parse_entries_array(char *id, unsigned long table_size,
+			 struct acpi_table_header *table_header,
+			 struct acpi_subtable_proc *proc,
+			 int proc_num, unsigned int max_entries)
+{
+	unsigned long table_end, subtable_len, entry_len;
+	struct acpi_subtable_entry entry;
+	int count = 0;
+	int errs = 0;
+	int i;
+
+	table_end = (unsigned long)table_header + table_header->length;
+
+	/* Parse all entries looking for a match. */
+
+	entry.type = acpi_get_subtable_type(id);
+	entry.hdr = (union acpi_subtable_headers *)
+	    ((unsigned long)table_header + table_size);
+	subtable_len = acpi_get_subtable_header_length(&entry);
+
+	while (((unsigned long)entry.hdr) + subtable_len  < table_end) {
+		if (max_entries && count >= max_entries)
+			break;
+
+		for (i = 0; i < proc_num; i++) {
+			if (acpi_get_entry_type(&entry) != proc[i].id)
+				continue;
+			if (!has_handler(&proc[i]) ||
+			    (!errs &&
+			     call_handler(&proc[i], entry.hdr, table_end))) {
+				errs++;
+				continue;
+			}
+
+			proc[i].count++;
+			break;
+		}
+		if (i != proc_num)
+			count++;
+
+		/*
+		 * If entry->length is 0, break from this loop to avoid
+		 * infinite loop.
+		 */
+		entry_len = acpi_get_entry_length(&entry);
+		if (entry_len == 0) {
+			pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id);
+			return -EINVAL;
+		}
+
+		entry.hdr = (union acpi_subtable_headers *)
+		    ((unsigned long)entry.hdr + entry_len);
+	}
+
+	if (max_entries && count > max_entries) {
+		pr_warn("[%4.4s:0x%02x] found the maximum %i entries\n",
+			id, proc->id, count);
+	}
+
+	return errs ? -EINVAL : count;
+}
+EXPORT_SYMBOL_GPL(acpi_parse_entries_array);