MIPS: JZ4740: Add prom support

Add support for initializing arcs_cmdline on JZ4740 based machines and
provides a prom_putchar implementation.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/1404/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/jz4740/prom.c

@@ -0,0 +1,68 @@
+/*
+ *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
+ *  JZ4740 SoC prom code
+ *
+ *  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;  either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  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.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/string.h>
+
+#include <linux/serial_reg.h>
+
+#include <asm/bootinfo.h>
+#include <asm/mach-jz4740/base.h>
+
+void jz4740_init_cmdline(int argc, char *argv[])
+{
+	unsigned int count = COMMAND_LINE_SIZE - 1;
+	int i;
+	char *dst = &(arcs_cmdline[0]);
+	char *src;
+
+	for (i = 1; i < argc && count; ++i) {
+		src = argv[i];
+		while (*src && count) {
+			*dst++ = *src++;
+			--count;
+		}
+		*dst++ = ' ';
+	}
+	if (i > 1)
+		--dst;
+
+	*dst = 0;
+}
+
+void __init prom_init(void)
+{
+	jz4740_init_cmdline((int)fw_arg0, (char **)fw_arg1);
+	mips_machtype = MACH_INGENIC_JZ4740;
+}
+
+void __init prom_free_prom_memory(void)
+{
+}
+
+#define UART_REG(_reg) ((void __iomem *)CKSEG1ADDR(JZ4740_UART0_BASE_ADDR + (_reg << 2)))
+
+void prom_putchar(char c)
+{
+	uint8_t lsr;
+
+	do {
+		lsr = readb(UART_REG(UART_LSR));
+	} while ((lsr & UART_LSR_TEMT) == 0);
+
+	writeb(c, UART_REG(UART_TX));
+}