lib: Support localized text of memory_training_desc in ux_locales.c

To support the localized text, we need to get the locale id by vboot
APIs and read raw string content file: preram_locales located at either
RO or RW.

The preram_locales file follows the format:
  [string_name_1] [\x00]
  [locale_id_1] [\x00] [localized_string_1] [\x00]
  [locale_id_2] [\x00] [localized_string_2] ...
  [string_name_2] [\x00] ...

This code will search for the correct localized string that its string
name is `memory_training_desc` and its locale ID matches the ID vb2api
returns. If no valid string found, we will try to display in English
(locale ID 0).

BUG=b:264666392
BRANCH=brya
TEST=emerge-brya coreboot chromeos-bmpblk chromeos-bootimage

Change-Id: I7e3c8d103c938a11b397c32c9228e44e31c3f01d
Signed-off-by: Hsuan Ting Chen <roccochen@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/75330
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/include/ux_locales.h

@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef _UX_LOCALES_H_
+#define _UX_LOCALES_H_
+
+#include <types.h>
+
+/* Unmap the preram_locales if it has been mapped. No-op otherwise. */
+void ux_locales_unmap(void);
+
+/*
+ * Get the localized text for a given string name.
+ * This function will try to read the language ID from vboot API, and search the
+ * corresponding translation from CBFS preram_locales.
+ */
+const char *ux_locales_get_text(const char *name);
+
+#endif  // _UX_LOCALES_H_

src/lib/Makefile.inc

@@ -428,3 +428,5 @@ cbfs-files-$(NEED_CBFS_POINTER) += header_pointer
 header_pointer-file := master_header_pointer.c:struct
 header_pointer-position := -4
 header_pointer-type := "cbfs header"
+
+romstage-y += ux_locales.c

src/lib/ux_locales.c

@@ -0,0 +1,167 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <cbfs.h>
+#include <console/console.h>
+#include <security/vboot/misc.h>
+#include <stddef.h>
+#include <string.h>
+#include <ux_locales.h>
+#include <vb2_api.h>
+
+#define LANG_ID_MAX 100
+#define LANG_ID_LEN 3
+#define PRERAM_LOCALES_NAME "preram_locales"
+
+/*
+ * Devices which support early vga have the capability to show localized text in
+ * Code Page 437 encoding. (see src/drivers/pc80/vga/vga_font_8x16.c)
+ *
+ * preram_locales located in CBFS is an uncompressed file located in either RO
+ * or RW CBFS. It contains the localization information in the following format:
+ *
+ * [string_name_1] [\x00]
+ * [language_id_1] [\x00] [localized_string_1] [\x00]
+ * [language_id_2] [\x00] [localized_string_2] [\x00] ...
+ * [string_name_2] [\x00] ...
+ *
+ * This file contains tools to locate the file and search for localized strings
+ * with specific language ID.
+ */
+
+/* Cached state for map (locales_get_map) and unmap (ux_locales_unmap). */
+struct preram_locales_state {
+	void *data;
+	size_t size;
+	bool initialized;
+};
+
+static struct preram_locales_state cached_state;
+
+void ux_locales_unmap(void)
+{
+	if (cached_state.initialized) {
+		if (cached_state.data)
+			cbfs_unmap(cached_state.data);
+		cached_state.initialized = false;
+		cached_state.size = 0;
+		cached_state.data = NULL;
+	}
+}
+
+/* Get the map address of preram_locales. */
+static void *locales_get_map(size_t *size_out, bool unmap)
+{
+	if (cached_state.initialized) {
+		*size_out = cached_state.size;
+		return cached_state.data;
+	}
+	cached_state.initialized = true;
+	cached_state.data = cbfs_ro_map(PRERAM_LOCALES_NAME,
+					&cached_state.size);
+	*size_out = cached_state.size;
+	return cached_state.data;
+}
+
+/* Move to the next string in the data. Strings are separated by 0x00. */
+static size_t move_next(const char *data, size_t offset, size_t size)
+{
+	if (offset >= size)
+		return size;
+	while (offset < size && data[offset] != '\0')
+		offset++;
+	offset++;
+	return offset;
+}
+
+/* Find the next occurrence of the specific string. */
+static size_t search_for(const char *data, size_t offset, size_t size,
+			 const char *str)
+{
+	if (offset >= size)
+		return size;
+	while (offset < size) {
+		if (!strncmp(data + offset, str, size - offset))
+			return offset;
+		offset = move_next(data, offset, size);
+	}
+	return size;
+}
+
+/* Find the next occurrence of the integer ID, where ID is less than 100. */
+static size_t search_for_id(const char *data, size_t offset, size_t size,
+			    int id)
+{
+	if (id >= LANG_ID_MAX)
+		return offset;
+	char int_to_str[LANG_ID_LEN] = {};
+	snprintf(int_to_str, LANG_ID_LEN, "%d", id);
+	return search_for(data, offset, size, int_to_str);
+}
+
+const char *ux_locales_get_text(const char *name)
+{
+	const char *data;
+	size_t size, offset, name_offset, next;
+	uint32_t lang_id;
+
+	data = locales_get_map(&size, false);
+	if (!data) {
+		printk(BIOS_INFO, "%s: %s not found.\n", __func__,
+		       PRERAM_LOCALES_NAME);
+		return NULL;
+	}
+
+	/* Get the language ID from vboot API. */
+	lang_id = vb2api_get_locale_id(vboot_get_context());
+	/* Validity check: Language ID should smaller than LANG_ID_MAX. */
+	if (lang_id >= LANG_ID_MAX) {
+		printk(BIOS_INFO, "%s: ID %d too big; fallback to 0.\n",
+		       __func__, lang_id);
+		lang_id = 0;
+	}
+
+	printk(BIOS_INFO, "%s: Search for %s with language ID: %u\n",
+	       __func__, name, lang_id);
+
+	offset = 0;
+	/* Search for name. */
+	offset = search_for(data, offset, size, name);
+	if (offset >= size) {
+		printk(BIOS_INFO, "%s: Name %s not found.\n", __func__, name);
+		return NULL;
+	}
+	name_offset = offset;
+
+	/* Search for language ID. */
+	offset = search_for_id(data,  name_offset, size, lang_id);
+	/* Language ID not supported; fallback to English if the current
+	 * language is not English (0). */
+	if (offset >= size) {
+		/*
+		 * Since we only support a limited charset, it is very normal
+		 * that a language is not supported and we fallback here
+		 * silently.
+		 */
+		if (lang_id != 0)
+			offset = search_for_id(data, name_offset, size, 0);
+		if (offset >= size) {
+			printk(BIOS_INFO, "%s: Neither %d nor 0 found.\n",
+			       __func__, lang_id);
+			return NULL;
+		}
+	}
+
+	offset =  move_next(data, offset, size);
+	if (offset >= size)
+		return NULL;
+
+	/* Validity check that the returned string must be NULL terminated. */
+	next = move_next(data, offset, size) - 1;
+	if (next >= size || data[next] != '\0') {
+		printk(BIOS_INFO, "%s: %s is not NULL terminated.\n",
+		       __func__, PRERAM_LOCALES_NAME);
+		return NULL;
+	}
+
+	return data + offset;
+}

src/soc/intel/alderlake/romstage/ux.c

@@ -3,9 +3,12 @@
 #include <console/console.h>
 #include <intelblocks/early_graphics.h>
 #include <pc80/vga.h>
+#include <ux_locales.h>
 
 #include "ux.h"
 
+#define UX_MEMORY_TRAINING_DESC "memory_training_desc"
+
 bool ux_inform_user_of_update_operation(const char *name)
 {
 	if (!CONFIG(MAINBOARD_HAS_EARLY_LIBGFXINIT) ||
@@ -13,10 +16,15 @@ bool ux_inform_user_of_update_operation(const char *name)
 		return false;
 
 	printk(BIOS_INFO, "Informing user on-display of %s.\n", name);
-	vga_write_text(VGA_TEXT_CENTER, VGA_TEXT_HORIZONTAL_MIDDLE,
+
-		       (const unsigned char *)
+	const char *text = ux_locales_get_text(UX_MEMORY_TRAINING_DESC);
-		       "Your device is finishing an update. "
+	/* No localized text found; fallback to built-in English. */
+	if (!text)
+		text = "Your device is finishing an update. "
 		       "This may take 1-2 minutes.\n"
-		       "Please do not turn off your device.");
+		       "Please do not turn off your device.";
+	vga_write_text(VGA_TEXT_CENTER, VGA_TEXT_HORIZONTAL_MIDDLE,
+		       (const unsigned char *)text);
+	ux_locales_unmap();
 	return true;
 }