acpi: introduce AML composer aml_append()

Adds for dynamic AML creation, which will be used
for piecing ASL/AML primitives together and hiding
from user/caller details about how nested context
should be closed/packed leaving less space for
mistakes and necessity to know how AML should be
encoded, allowing user to concentrate on ASL
representation instead.

For example it will allow to create AML like this:

init_aml_allocator();
...
Aml *scope = aml_scope("PCI0")
Aml *dev = aml_device("PM")
    aml_append(dev, aml_name_decl("_ADR", aml_int(addr)))
aml_append(scope, dev);
...
free_aml_allocator();
Signed-off-by: NIgor Mammedov <imammedo@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/acpi/aml-build.c

@@ -25,6 +25,7 @@
 #include <stdbool.h>
 #include <string.h>
 #include "hw/acpi/aml-build.h"
+#include "qemu/bswap.h"
 
 GArray *build_alloc_array(void)
 {
@@ -257,3 +258,80 @@ void build_append_int(GArray *table, uint32_t value)
         build_append_value(table, value, 4);
     }
 }
+
+static GPtrArray *alloc_list;
+
+static Aml *aml_alloc(void)
+{
+    Aml *var = g_new0(typeof(*var), 1);
+
+    g_ptr_array_add(alloc_list, var);
+    var->block_flags = AML_NO_OPCODE;
+    var->buf = build_alloc_array();
+    return var;
+}
+
+static void aml_free(gpointer data)
+{
+    Aml *var = data;
+    build_free_array(var->buf);
+}
+
+Aml *init_aml_allocator(void)
+{
+    Aml *var;
+
+    assert(!alloc_list);
+    alloc_list = g_ptr_array_new_with_free_func(aml_free);
+    var = aml_alloc();
+    return var;
+}
+
+void free_aml_allocator(void)
+{
+    g_ptr_array_free(alloc_list, true);
+    alloc_list = 0;
+}
+
+/* pack data with DefBuffer encoding */
+static void build_buffer(GArray *array, uint8_t op)
+{
+    GArray *data = build_alloc_array();
+
+    build_append_int(data, array->len);
+    g_array_prepend_vals(array, data->data, data->len);
+    build_free_array(data);
+    build_package(array, op);
+}
+
+void aml_append(Aml *parent_ctx, Aml *child)
+{
+    switch (child->block_flags) {
+    case AML_OPCODE:
+        build_append_byte(parent_ctx->buf, child->op);
+        break;
+    case AML_EXT_PACKAGE:
+        build_extop_package(child->buf, child->op);
+        break;
+    case AML_PACKAGE:
+        build_package(child->buf, child->op);
+        break;
+    case AML_RES_TEMPLATE:
+        build_append_byte(child->buf, 0x79); /* EndTag */
+        /*
+         * checksum operations are treated as succeeded if checksum
+         * field is zero. [ACPI Spec 1.0b, 6.4.2.8 End Tag]
+         */
+        build_append_byte(child->buf, 0);
+        /* fall through, to pack resources in buffer */
+    case AML_BUFFER:
+        build_buffer(child->buf, child->op);
+        break;
+    case AML_NO_OPCODE:
+        break;
+    default:
+        assert(0);
+        break;
+    }
+    build_append_array(parent_ctx->buf, child->buf);
+}

include/hw/acpi/aml-build.h

@@ -5,6 +5,61 @@
 #include <glib.h>
 #include "qemu/compiler.h"
 
+typedef enum {
+    AML_NO_OPCODE = 0,/* has only data */
+    AML_OPCODE,       /* has opcode optionally followed by data */
+    AML_PACKAGE,      /* has opcode and uses PkgLength for its length */
+    AML_EXT_PACKAGE,  /* ame as AML_PACKAGE but also has 'ExOpPrefix' */
+    AML_BUFFER,       /* data encoded as 'DefBuffer' */
+    AML_RES_TEMPLATE, /* encoded as ResourceTemplate macro */
+} AmlBlockFlags;
+
+struct Aml {
+    GArray *buf;
+
+    /*< private >*/
+    uint8_t op;
+    AmlBlockFlags block_flags;
+};
+typedef struct Aml Aml;
+
+/**
+ * init_aml_allocator:
+ *
+ * Called for initializing API allocator which allow to use
+ * AML API.
+ * Returns: toplevel container which accumulates all other
+ * AML elements for a table.
+ */
+Aml *init_aml_allocator(void);
+
+/**
+ * free_aml_allocator:
+ *
+ * Releases all elements used by AML API, frees associated memory
+ * and invalidates AML allocator. After this call @init_aml_allocator
+ * should be called again if AML API is to be used again.
+ */
+void free_aml_allocator(void);
+
+/**
+ * aml_append:
+ * @parent_ctx: context to which @child element is added
+ * @child: element that is copied into @parent_ctx context
+ *
+ * Joins Aml elements together and helps to construct AML tables
+ * Examle of usage:
+ *   Aml *table = aml_def_block("SSDT", ...);
+ *   Aml *sb = aml_scope("\_SB");
+ *   Aml *dev = aml_device("PCI0");
+ *
+ *   aml_append(dev, aml_name_decl("HID", aml_eisaid("PNP0A03")));
+ *   aml_append(sb, dev);
+ *   aml_append(table, sb);
+ */
+void aml_append(Aml *parent_ctx, Aml *child);
+
+/* other helpers */
 GArray *build_alloc_array(void);
 void build_free_array(GArray *array);
 void build_prepend_byte(GArray *array, uint8_t val);