x86: Add console command to display CBMEM console buffer

This command is useful to allow to observe messages generated by
coreboot and u-boot until present. In particular it is handy when
u-boot is instrumented to fall through into console mode on startup
errors.

Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/misc/cbmem_console.c

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2011 The ChromiumOS Authors.  All rights reserved.
+ *
+ * This program 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; version 2 of the License.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA, 02110-1301 USA
+ */
+
+#include <common.h>
+
+#ifndef CONFIG_SYS_COREBOOT
+#error This driver requires coreboot
+#endif
+
+#include <asm/arch/sysinfo.h>
+
+struct cbmem_console {
+	u32 buffer_size;
+	u32 buffer_cursor;
+	u8  buffer_body[0];
+}  __attribute__ ((__packed__));
+
+static struct cbmem_console *cbmem_console_p;
+
+void cbmemc_putc(char data)
+{
+	int cursor;
+
+	cursor = cbmem_console_p->buffer_cursor++;
+	if (cursor < cbmem_console_p->buffer_size)
+		cbmem_console_p->buffer_body[cursor] = data;
+}
+
+void cbmemc_puts(const char *str)
+{
+	char c;
+
+	while ((c = *str++) != 0)
+		cbmemc_putc(c);
+}
+
+int cbmemc_init(void)
+{
+	int rc;
+	struct stdio_dev cons_dev;
+	cbmem_console_p = lib_sysinfo.cbmem_cons;
+
+	memset(&cons_dev, 0, sizeof(cons_dev));
+
+	strcpy(cons_dev.name, "cbmem");
+	cons_dev.flags = DEV_FLAGS_OUTPUT; /* Output only */
+	cons_dev.putc  = cbmemc_putc;
+	cons_dev.puts  = cbmemc_puts;
+
+	rc = stdio_register(&cons_dev);
+
+	return (rc == 0) ? 1 : rc;
+}