[Xen-devel] [PATCH v3 25/62] acpi/table: Introduce acpi_get_entry to get specified entry

[shannon.zhao@xxxxxxxxxx]

From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>

When constructing MADT table for Dom0, it needs to create GICC subtable
according to the dom0_max_vcpus. This function could be used for get the
specified entry.

Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
---
 xen/drivers/acpi/tables.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 xen/include/xen/acpi.h    |  4 ++++
 2 files changed, 49 insertions(+)

diff --git a/xen/drivers/acpi/tables.c b/xen/drivers/acpi/tables.c
index 2fba206..3ba8bad 100644
--- a/xen/drivers/acpi/tables.c
+++ b/xen/drivers/acpi/tables.c
@@ -221,6 +221,51 @@ void __init acpi_table_print_madt_entry(struct 
acpi_subtable_header *header)
        }
 }
 
+struct acpi_subtable_header * __init
+acpi_get_entry(char *id, unsigned long table_size,
+              struct acpi_table_header *table_header, int entry_id,
+              unsigned int entry_index)
+{
+       struct acpi_subtable_header *entry;
+       unsigned int count = 0;
+       unsigned long table_end;
+
+       if ( !table_size )
+               return NULL;
+
+       if ( !table_header )
+       {
+               printk("Table header not present\n");
+               return NULL;
+       }
+
+       table_end = (unsigned long)table_header + table_header->length;
+
+       /* Parse all entries looking for a match. */
+       entry = (struct acpi_subtable_header *)
+           ((unsigned long)table_header + table_size);
+
+       while (((unsigned long)entry) + sizeof(struct acpi_subtable_header) <
+              table_end) {
+               if (entry->length < sizeof(*entry)) {
+                       printk(KERN_ERR PREFIX "[%4.4s:%#x] Invalid length\n",
+                              id, entry_id);
+                       return NULL;
+               }
+
+               if (entry->type == entry_id) {
+                       if (count == entry_index)
+                               return entry;
+                       count++;
+               }
+
+               entry = (struct acpi_subtable_header *)
+                   ((unsigned long)entry + entry->length);
+       }
+
+       return NULL;
+}
+
 int __init
 acpi_parse_entries(char *id,
                      unsigned long table_size,
diff --git a/xen/include/xen/acpi.h b/xen/include/xen/acpi.h
index 23f8261..3339374 100644
--- a/xen/include/xen/acpi.h
+++ b/xen/include/xen/acpi.h
@@ -72,6 +72,10 @@ int acpi_table_init (void);
 int acpi_table_parse(char *id, acpi_table_handler handler);
 int acpi_table_parse_entries(char *id, unsigned long table_size,
        int entry_id, acpi_table_entry_handler handler, unsigned int 
max_entries);
+struct acpi_subtable_header *
+acpi_get_entry(char *id, unsigned long table_size,
+              struct acpi_table_header *table_header, int entry_id,
+              unsigned int entry_index);
 int acpi_parse_entries(char *id, unsigned long table_size,
        acpi_table_entry_handler handler, struct acpi_table_header 
*table_header,
        int entry_id, unsigned int max_entries);
-- 
2.1.0


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