ACPI / table: Add new function to get table entries

The acpi_table_parse() function has a callback that
passes a pointer to a table_header. Add a new function
which takes this pointer and parses its entries. This
eliminates the need to re-traverse all the tables for
each call. e.g. as in acpi_table_parse_madt() which is
normally called after acpi_table_parse().

Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
Signed-off-by: Tomasz Nowicki <tomasz.nowicki@linaro.org>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/tables.c

@@ -190,30 +190,24 @@ void acpi_table_print_madt_entry(struct acpi_subtable_header *header)
 	}
 }
 
-
 int __init
-acpi_table_parse_entries(char *id,
-			     unsigned long table_size,
-			     int entry_id,
-			     acpi_tbl_entry_handler handler,
-			     unsigned int max_entries)
+acpi_parse_entries(char *id, unsigned long table_size,
+		acpi_tbl_entry_handler handler,
+		struct acpi_table_header *table_header,
+		int entry_id, unsigned int max_entries)
 {
-	struct acpi_table_header *table_header = NULL;
 	struct acpi_subtable_header *entry;
-	unsigned int count = 0;
+	int count = 0;
 	unsigned long table_end;
-	acpi_size tbl_size;
 
 	if (acpi_disabled)
 		return -ENODEV;
 
-	if (!handler)
+	if (!id || !handler)
 		return -EINVAL;
 
-	if (strncmp(id, ACPI_SIG_MADT, 4) == 0)
-		acpi_get_table_with_size(id, acpi_apic_instance, &table_header, &tbl_size);
-	else
-		acpi_get_table_with_size(id, 0, &table_header, &tbl_size);
+	if (!table_size)
+		return -EINVAL;
 
 	if (!table_header) {
 		pr_warn("%4.4s not present\n", id);
@@ -232,7 +226,7 @@ acpi_table_parse_entries(char *id,
 		if (entry->type == entry_id
 		    && (!max_entries || count++ < max_entries))
 			if (handler(entry, table_end))
-				goto err;
+				return -EINVAL;
 
 		/*
 		 * If entry->length is 0, break from this loop to avoid
@@ -240,22 +234,53 @@ acpi_table_parse_entries(char *id,
 		 */
 		if (entry->length == 0) {
 			pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, entry_id);
-			goto err;
+			return -EINVAL;
 		}
 
 		entry = (struct acpi_subtable_header *)
 		    ((unsigned long)entry + entry->length);
 	}
+
 	if (max_entries && count > max_entries) {
 		pr_warn("[%4.4s:0x%02x] ignored %i entries of %i found\n",
 			id, entry_id, count - max_entries, count);
 	}
 
+	return count;
+}
+
+int __init
+acpi_table_parse_entries(char *id,
+			 unsigned long table_size,
+			 int entry_id,
+			 acpi_tbl_entry_handler handler,
+			 unsigned int max_entries)
+{
+	struct acpi_table_header *table_header = NULL;
+	acpi_size tbl_size;
+	int count;
+	u32 instance = 0;
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	if (!id || !handler)
+		return -EINVAL;
+
+	if (!strncmp(id, ACPI_SIG_MADT, 4))
+		instance = acpi_apic_instance;
+
+	acpi_get_table_with_size(id, instance, &table_header, &tbl_size);
+	if (!table_header) {
+		pr_warn("%4.4s not present\n", id);
+		return -ENODEV;
+	}
+
+	count = acpi_parse_entries(id, table_size, handler, table_header,
+			entry_id, max_entries);
+
 	early_acpi_os_unmap_memory((char *)table_header, tbl_size);
 	return count;
-err:
-	early_acpi_os_unmap_memory((char *)table_header, tbl_size);
-	return -EINVAL;
 }
 
 int __init

include/linux/acpi.h

@@ -123,6 +123,10 @@ int acpi_numa_init (void);
 
 int acpi_table_init (void);
 int acpi_table_parse(char *id, acpi_tbl_table_handler handler);
+int __init acpi_parse_entries(char *id, unsigned long table_size,
+			      acpi_tbl_entry_handler handler,
+			      struct acpi_table_header *table_header,
+			      int entry_id, unsigned int max_entries);
 int __init acpi_table_parse_entries(char *id, unsigned long table_size,
 				    int entry_id,
 				    acpi_tbl_entry_handler handler,