ieee1275/ibmvpm: Move TPM initialization functions to own file

Move common initialization functions from the ibmvtpm driver module into
tcg2.c that will be moved into the new TCG2 driver in a subsequent patch.
Make the functions available to the ibmvtpm driver as public functions
and variables.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/lib/ieee1275/tcg2.c

@@ -0,0 +1,61 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2024 IBM Corporation
+ *  Copyright (C) 2024 Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/types.h>
+#include <grub/tpm.h>
+#include <grub/ieee1275/tpm.h>
+#include <grub/mm.h>
+#include <grub/misc.h>
+
+grub_ieee1275_ihandle_t grub_ieee1275_tpm_ihandle;
+grub_uint8_t grub_ieee1275_tpm_version;
+
+static void
+tpm_get_tpm_version (void)
+{
+  grub_ieee1275_phandle_t vtpm;
+  char buffer[20];
+
+  if (!grub_ieee1275_finddevice ("/vdevice/vtpm", &vtpm) &&
+      !grub_ieee1275_get_property (vtpm, "compatible", buffer,
+                                  sizeof (buffer), NULL) &&
+      !grub_strcmp (buffer, "IBM,vtpm20"))
+    grub_ieee1275_tpm_version = 2;
+}
+
+grub_err_t
+grub_ieee1275_tpm_init (void)
+{
+  static int init_success = 0;
+
+  if (!init_success)
+    {
+      if (grub_ieee1275_open ("/vdevice/vtpm", &grub_ieee1275_tpm_ihandle) < 0)
+	{
+	  grub_ieee1275_tpm_ihandle = GRUB_IEEE1275_IHANDLE_INVALID;
+	  return GRUB_ERR_UNKNOWN_DEVICE;
+	}
+
+      init_success = 1;
+
+      tpm_get_tpm_version ();
+    }
+
+  return GRUB_ERR_NONE;
+}