Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

12 files changed, 622 insertions, 0 deletions

diff --git a/arch/mips/boot/compressed/.gitignore b/arch/mips/boot/compressed/.gitignore
new file mode 100644
index 000000000..d35839561
--- /dev/null
+++ b/arch/mips/boot/compressed/.gitignore
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+ashldi3.c
+bswapsi.c
diff --git a/arch/mips/boot/compressed/Makefile b/arch/mips/boot/compressed/Makefile
new file mode 100644
index 000000000..eae0fad30
--- /dev/null
+++ b/arch/mips/boot/compressed/Makefile
@@ -0,0 +1,155 @@
+#
+# This file is subject to the terms and conditions of the GNU General Public
+# License.
+#
+# Adapted for MIPS Pete Popov, Dan Malek
+#
+# Copyright (C) 1994 by Linus Torvalds
+# Adapted for PowerPC by Gary Thomas
+# modified by Cort (cort@cs.nmt.edu)
+#
+# Copyright (C) 2009 Lemote Inc. & DSLab, Lanzhou University
+# Author: Wu Zhangjin <wuzhangjin@gmail.com>
+#
+
+include $(srctree)/arch/mips/Kbuild.platforms
+
+# set the default size of the mallocing area for decompressing
+BOOT_HEAP_SIZE := 0x400000
+
+# Disable Function Tracer
+KBUILD_CFLAGS := $(filter-out -pg, $(KBUILD_CFLAGS))
+
+KBUILD_CFLAGS := $(filter-out -fstack-protector, $(KBUILD_CFLAGS))
+
+# Disable lq/sq in zboot
+ifdef CONFIG_CPU_LOONGSON64
+KBUILD_CFLAGS := $(filter-out -march=loongson3a, $(KBUILD_CFLAGS)) -march=mips64r2
+endif
+
+KBUILD_CFLAGS := $(KBUILD_CFLAGS) -D__KERNEL__ -D__DISABLE_EXPORTS \
+	-DBOOT_HEAP_SIZE=$(BOOT_HEAP_SIZE) -D"VMLINUX_LOAD_ADDRESS_ULL=$(VMLINUX_LOAD_ADDRESS)ull"
+
+KBUILD_AFLAGS := $(KBUILD_AFLAGS) -D__ASSEMBLY__ \
+	-DBOOT_HEAP_SIZE=$(BOOT_HEAP_SIZE) \
+	-DKERNEL_ENTRY=$(VMLINUX_ENTRY_ADDRESS)
+
+# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
+KCOV_INSTRUMENT		:= n
+UBSAN_SANITIZE := n
+
+# decompressor objects (linked with vmlinuz)
+vmlinuzobjs-y := $(obj)/head.o $(obj)/decompress.o $(obj)/string.o $(obj)/bswapsi.o
+
+ifdef CONFIG_DEBUG_ZBOOT
+vmlinuzobjs-$(CONFIG_DEBUG_ZBOOT)		   += $(obj)/dbg.o
+vmlinuzobjs-$(CONFIG_SYS_SUPPORTS_ZBOOT_UART16550) += $(obj)/uart-16550.o
+vmlinuzobjs-$(CONFIG_SYS_SUPPORTS_ZBOOT_UART_PROM) += $(obj)/uart-prom.o
+vmlinuzobjs-$(CONFIG_MIPS_ALCHEMY)		   += $(obj)/uart-alchemy.o
+vmlinuzobjs-$(CONFIG_ATH79)			   += $(obj)/uart-ath79.o
+endif
+
+extra-y += uart-ath79.c
+$(obj)/uart-ath79.c: $(srctree)/arch/mips/ath79/early_printk.c
+	$(call cmd,shipped)
+
+vmlinuzobjs-$(CONFIG_KERNEL_XZ) += $(obj)/ashldi3.o
+
+extra-y += ashldi3.c
+$(obj)/ashldi3.c: $(obj)/%.c: $(srctree)/lib/%.c FORCE
+	$(call if_changed,shipped)
+
+extra-y += bswapsi.c
+$(obj)/bswapsi.c: $(obj)/%.c: $(srctree)/arch/mips/lib/%.c FORCE
+	$(call if_changed,shipped)
+
+targets := $(notdir $(vmlinuzobjs-y))
+
+targets += vmlinux.bin
+OBJCOPYFLAGS_vmlinux.bin := $(OBJCOPYFLAGS) -O binary -R .comment -S
+$(obj)/vmlinux.bin: $(KBUILD_IMAGE) FORCE
+	$(call if_changed,objcopy)
+
+tool_$(CONFIG_KERNEL_GZIP)    = gzip
+tool_$(CONFIG_KERNEL_BZIP2)   = bzip2
+tool_$(CONFIG_KERNEL_LZ4)     = lz4
+tool_$(CONFIG_KERNEL_LZMA)    = lzma
+tool_$(CONFIG_KERNEL_LZO)     = lzo
+tool_$(CONFIG_KERNEL_XZ)      = xzkern
+tool_$(CONFIG_KERNEL_ZSTD)    = zstd22
+
+targets += vmlinux.bin.z
+$(obj)/vmlinux.bin.z: $(obj)/vmlinux.bin FORCE
+	$(call if_changed,$(tool_y))
+
+targets += piggy.o dummy.o
+OBJCOPYFLAGS_piggy.o := --add-section=.image=$(obj)/vmlinux.bin.z \
+			--set-section-flags=.image=contents,alloc,load,readonly,data
+$(obj)/piggy.o: $(obj)/dummy.o $(obj)/vmlinux.bin.z FORCE
+	$(call if_changed,objcopy)
+
+HOSTCFLAGS_calc_vmlinuz_load_addr.o += $(LINUXINCLUDE)
+
+# Calculate the load address of the compressed kernel image
+hostprogs := calc_vmlinuz_load_addr
+
+ifneq ($(zload-y),)
+VMLINUZ_LOAD_ADDRESS := $(zload-y)
+else
+VMLINUZ_LOAD_ADDRESS = $(shell $(obj)/calc_vmlinuz_load_addr \
+		$(obj)/vmlinux.bin $(LINKER_LOAD_ADDRESS))
+endif
+UIMAGE_LOADADDR = $(VMLINUZ_LOAD_ADDRESS)
+
+vmlinuzobjs-y += $(obj)/piggy.o
+
+quiet_cmd_zld = LD      $@
+      cmd_zld = $(LD) $(KBUILD_LDFLAGS) -Ttext $(VMLINUZ_LOAD_ADDRESS) -T $< $(vmlinuzobjs-y) -o $@
+quiet_cmd_strip = STRIP	  $@
+      cmd_strip = $(STRIP) -s $@
+vmlinuz: $(src)/ld.script $(vmlinuzobjs-y) $(obj)/calc_vmlinuz_load_addr
+	$(call cmd,zld)
+	$(call cmd,strip)
+
+#
+# Some DECstations need all possible sections of an ECOFF executable
+#
+ifdef CONFIG_MACH_DECSTATION
+  e2eflag := -a
+endif
+
+# elf2ecoff can only handle 32bit image
+hostprogs += ../elf2ecoff
+
+ifdef CONFIG_32BIT
+	VMLINUZ = vmlinuz
+else
+	VMLINUZ = vmlinuz.32
+endif
+
+quiet_cmd_32 = OBJCOPY $@
+      cmd_32 = $(OBJCOPY) -O $(32bit-bfd) $(OBJCOPYFLAGS) $< $@
+vmlinuz.32: vmlinuz
+	$(call cmd,32)
+
+quiet_cmd_ecoff = ECOFF	  $@
+      cmd_ecoff = $< $(VMLINUZ) $@ $(e2eflag)
+vmlinuz.ecoff: $(obj)/../elf2ecoff $(VMLINUZ)
+	$(call cmd,ecoff)
+
+OBJCOPYFLAGS_vmlinuz.bin := $(OBJCOPYFLAGS) -O binary
+vmlinuz.bin: vmlinuz
+	$(call cmd,objcopy)
+
+OBJCOPYFLAGS_vmlinuz.srec := $(OBJCOPYFLAGS) -S -O srec
+vmlinuz.srec: vmlinuz
+	$(call cmd,objcopy)
+
+uzImage.bin: vmlinuz.bin FORCE
+	$(call if_changed,uimage,none)
+
+clean-files += $(objtree)/vmlinuz
+clean-files += $(objtree)/vmlinuz.32
+clean-files += $(objtree)/vmlinuz.ecoff
+clean-files += $(objtree)/vmlinuz.bin
+clean-files += $(objtree)/vmlinuz.srec
diff --git a/arch/mips/boot/compressed/calc_vmlinuz_load_addr.c b/arch/mips/boot/compressed/calc_vmlinuz_load_addr.c
new file mode 100644
index 000000000..080b926d2
--- /dev/null
+++ b/arch/mips/boot/compressed/calc_vmlinuz_load_addr.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2010 "Wu Zhangjin" <wuzhangjin@gmail.com>
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <linux/sizes.h>
+
+int main(int argc, char *argv[])
+{
+	unsigned long long vmlinux_size, vmlinux_load_addr, vmlinuz_load_addr;
+	struct stat sb;
+
+	if (argc != 3) {
+		fprintf(stderr, "Usage: %s <pathname> <vmlinux_load_addr>\n",
+				argv[0]);
+		return EXIT_FAILURE;
+	}
+
+	if (stat(argv[1], &sb) == -1) {
+		perror("stat");
+		return EXIT_FAILURE;
+	}
+
+	/* Convert hex characters to dec number */
+	errno = 0;
+	if (sscanf(argv[2], "%llx", &vmlinux_load_addr) != 1) {
+		if (errno != 0)
+			perror("sscanf");
+		else
+			fprintf(stderr, "No matching characters\n");
+
+		return EXIT_FAILURE;
+	}
+
+	vmlinux_size = (uint64_t)sb.st_size;
+	vmlinuz_load_addr = vmlinux_load_addr + vmlinux_size;
+
+	/*
+	 * Align with 64KB: KEXEC needs load sections to be aligned to PAGE_SIZE,
+	 * which may be as large as 64KB depending on the kernel configuration.
+	 */
+
+	vmlinuz_load_addr += (SZ_64K - vmlinux_size % SZ_64K);
+
+	printf("0x%llx\n", vmlinuz_load_addr);
+
+	return EXIT_SUCCESS;
+}
diff --git a/arch/mips/boot/compressed/dbg.c b/arch/mips/boot/compressed/dbg.c
new file mode 100644
index 000000000..f6728a8fd
--- /dev/null
+++ b/arch/mips/boot/compressed/dbg.c
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * MIPS-specific debug support for pre-boot environment
+ *
+ * NOTE: putc() is board specific, if your board have a 16550 compatible uart,
+ * please select SYS_SUPPORTS_ZBOOT_UART16550 for your machine. othewise, you
+ * need to implement your own putc().
+ */
+#include <linux/compiler.h>
+#include <linux/types.h>
+
+void __weak putc(char c)
+{
+}
+
+void puts(const char *s)
+{
+	char c;
+	while ((c = *s++) != '\0') {
+		putc(c);
+		if (c == '\n')
+			putc('\r');
+	}
+}
+
+void puthex(unsigned long long val)
+{
+
+	unsigned char buf[10];
+	int i;
+	for (i = 7; i >= 0; i--) {
+		buf[i] = "0123456789ABCDEF"[val & 0x0F];
+		val >>= 4;
+	}
+	buf[8] = '\0';
+	puts(buf);
+}
diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c
new file mode 100644
index 000000000..1e91155be
--- /dev/null
+++ b/arch/mips/boot/compressed/decompress.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2001 MontaVista Software Inc.
+ * Author: Matt Porter <mporter@mvista.com>
+ *
+ * Copyright (C) 2009 Lemote, Inc.
+ * Author: Wu Zhangjin <wuzhangjin@gmail.com>
+ */
+
+#define DISABLE_BRANCH_PROFILING
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/libfdt.h>
+
+#include <asm/addrspace.h>
+#include <asm/unaligned.h>
+
+/*
+ * These two variables specify the free mem region
+ * that can be used for temporary malloc area
+ */
+unsigned long free_mem_ptr;
+unsigned long free_mem_end_ptr;
+
+/* The linker tells us where the image is. */
+extern unsigned char __image_begin, __image_end;
+
+/* debug interfaces  */
+#ifdef CONFIG_DEBUG_ZBOOT
+extern void puts(const char *s);
+extern void puthex(unsigned long long val);
+#else
+#define puts(s) do {} while (0)
+#define puthex(val) do {} while (0)
+#endif
+
+extern char __appended_dtb[];
+
+void error(char *x)
+{
+	puts("\n\n");
+	puts(x);
+	puts("\n\n -- System halted");
+
+	while (1)
+		;	/* Halt */
+}
+
+/* activate the code for pre-boot environment */
+#define STATIC static
+
+#ifdef CONFIG_KERNEL_GZIP
+#include "../../../../lib/decompress_inflate.c"
+#endif
+
+#ifdef CONFIG_KERNEL_BZIP2
+#include "../../../../lib/decompress_bunzip2.c"
+#endif
+
+#ifdef CONFIG_KERNEL_LZ4
+#include "../../../../lib/decompress_unlz4.c"
+#endif
+
+#ifdef CONFIG_KERNEL_LZMA
+#include "../../../../lib/decompress_unlzma.c"
+#endif
+
+#ifdef CONFIG_KERNEL_LZO
+#include "../../../../lib/decompress_unlzo.c"
+#endif
+
+#ifdef CONFIG_KERNEL_XZ
+#include "../../../../lib/decompress_unxz.c"
+#endif
+
+#ifdef CONFIG_KERNEL_ZSTD
+#include "../../../../lib/decompress_unzstd.c"
+#endif
+
+const unsigned long __stack_chk_guard = 0x000a0dff;
+
+void __stack_chk_fail(void)
+{
+	error("stack-protector: Kernel stack is corrupted\n");
+}
+
+void decompress_kernel(unsigned long boot_heap_start)
+{
+	unsigned long zimage_start, zimage_size;
+
+	zimage_start = (unsigned long)(&__image_begin);
+	zimage_size = (unsigned long)(&__image_end) -
+	    (unsigned long)(&__image_begin);
+
+	puts("zimage at:     ");
+	puthex(zimage_start);
+	puts(" ");
+	puthex(zimage_size + zimage_start);
+	puts("\n");
+
+	/* This area are prepared for mallocing when decompressing */
+	free_mem_ptr = boot_heap_start;
+	free_mem_end_ptr = boot_heap_start + BOOT_HEAP_SIZE;
+
+	/* Display standard Linux/MIPS boot prompt */
+	puts("Uncompressing Linux at load address ");
+	puthex(VMLINUX_LOAD_ADDRESS_ULL);
+	puts("\n");
+
+	/* Decompress the kernel with according algorithm */
+	__decompress((char *)zimage_start, zimage_size, 0, 0,
+		   (void *)VMLINUX_LOAD_ADDRESS_ULL, 0, 0, error);
+
+	if (IS_ENABLED(CONFIG_MIPS_RAW_APPENDED_DTB) &&
+	    fdt_magic((void *)&__appended_dtb) == FDT_MAGIC) {
+		unsigned int image_size, dtb_size;
+
+		dtb_size = fdt_totalsize((void *)&__appended_dtb);
+
+		/* last four bytes is always image size in little endian */
+		image_size = get_unaligned_le32((void *)&__image_end - 4);
+
+		/* copy dtb to where the booted kernel will expect it */
+		memcpy((void *)VMLINUX_LOAD_ADDRESS_ULL + image_size,
+		       __appended_dtb, dtb_size);
+	}
+
+	/* FIXME: should we flush cache here? */
+	puts("Now, booting the kernel...\n");
+}
diff --git a/arch/mips/boot/compressed/dummy.c b/arch/mips/boot/compressed/dummy.c
new file mode 100644
index 000000000..31dbf45bf
--- /dev/null
+++ b/arch/mips/boot/compressed/dummy.c
@@ -0,0 +1,4 @@
+int main(void)
+{
+	return 0;
+}
diff --git a/arch/mips/boot/compressed/head.S b/arch/mips/boot/compressed/head.S
new file mode 100644
index 000000000..409cb483a
--- /dev/null
+++ b/arch/mips/boot/compressed/head.S
@@ -0,0 +1,56 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1994, 1995 Waldorf Electronics
+ * Written by Ralf Baechle and Andreas Busse
+ * Copyright (C) 1995 - 1999 Ralf Baechle
+ * Copyright (C) 1996 Paul M. Antoine
+ * Modified for DECStation and hence R3000 support by Paul M. Antoine
+ * Further modifications by David S. Miller and Harald Koerfgen
+ * Copyright (C) 1999 Silicon Graphics, Inc.
+ */
+
+#include <asm/asm.h>
+#include <asm/regdef.h>
+
+	.set noreorder
+	.cprestore
+	LEAF(start)
+start:
+	/* Save boot rom start args */
+	move	s0, a0
+	move	s1, a1
+	move	s2, a2
+	move	s3, a3
+
+	/* Clear BSS */
+	PTR_LA	a0, _edata
+	PTR_LA	a2, _end
+1:	sw	zero, 0(a0)
+	bne	a2, a0, 1b
+	 addiu	a0, a0, 4
+
+	PTR_LA	a0, (.heap)	     /* heap address */
+	PTR_LA	sp, (.stack + 8192)  /* stack address */
+
+	PTR_LA	ra, 2f
+	PTR_LA	k0, decompress_kernel
+	jr	k0
+	 nop
+2:
+	move	a0, s0
+	move	a1, s1
+	move	a2, s2
+	move	a3, s3
+	PTR_LI	k0, KERNEL_ENTRY
+	jr	k0
+	 nop
+3:
+	b	3b
+	 nop
+	END(start)
+
+	.comm .heap,BOOT_HEAP_SIZE,4
+	.comm .stack,4096*2,4
diff --git a/arch/mips/boot/compressed/ld.script b/arch/mips/boot/compressed/ld.script
new file mode 100644
index 000000000..2ed08fbef
--- /dev/null
+++ b/arch/mips/boot/compressed/ld.script
@@ -0,0 +1,57 @@
+/*
+ * ld.script for compressed kernel support of MIPS
+ *
+ * Copyright (C) 2009 Lemote Inc.
+ * Author: Wu Zhangjin <wuzhanjing@gmail.com>
+ * Copyright (C) 2010 "Wu Zhangjin" <wuzhanjing@gmail.com>
+ */
+
+OUTPUT_ARCH(mips)
+ENTRY(start)
+PHDRS {
+	text PT_LOAD FLAGS(7); /* RWX */
+}
+SECTIONS
+{
+	/* Text and read-only data */
+	/* . = VMLINUZ_LOAD_ADDRESS; */
+	.text : {
+		*(.text)
+		*(.rodata)
+	}: text
+	/* End of text section */
+
+	/* Writable data */
+	.data : {
+		*(.data)
+		/* Put the compressed image here */
+		__image_begin = .;
+		*(.image)
+		__image_end = .;
+		CONSTRUCTORS
+		. = ALIGN(16);
+	}
+	__appended_dtb = .;
+	/* leave space for appended DTB */
+	. += 0x100000;
+
+	_edata = .;
+	/* End of data section */
+
+	/* BSS */
+	.bss : {
+		*(.bss)
+	}
+	. = ALIGN(16);
+	_end = .;
+
+	/* Sections to be discarded */
+	/DISCARD/ : {
+		*(.MIPS.options)
+		*(.options)
+		*(.pdr)
+		*(.reginfo)
+		*(.comment)
+		*(.note)
+	}
+}
diff --git a/arch/mips/boot/compressed/string.c b/arch/mips/boot/compressed/string.c
new file mode 100644
index 000000000..0b593b709
--- /dev/null
+++ b/arch/mips/boot/compressed/string.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * arch/mips/boot/compressed/string.c
+ *
+ * Very small subset of simple string routines
+ */
+
+#include <linux/compiler_attributes.h>
+#include <linux/types.h>
+
+void *memcpy(void *dest, const void *src, size_t n)
+{
+	int i;
+	const char *s = src;
+	char *d = dest;
+
+	for (i = 0; i < n; i++)
+		d[i] = s[i];
+	return dest;
+}
+
+void *memset(void *s, int c, size_t n)
+{
+	int i;
+	char *ss = s;
+
+	for (i = 0; i < n; i++)
+		ss[i] = c;
+	return s;
+}
+
+void * __weak memmove(void *dest, const void *src, size_t n)
+{
+	unsigned int i;
+	const char *s = src;
+	char *d = dest;
+
+	if ((uintptr_t)dest < (uintptr_t)src) {
+		for (i = 0; i < n; i++)
+			d[i] = s[i];
+	} else {
+		for (i = n; i > 0; i--)
+			d[i - 1] = s[i - 1];
+	}
+	return dest;
+}
diff --git a/arch/mips/boot/compressed/uart-16550.c b/arch/mips/boot/compressed/uart-16550.c
new file mode 100644
index 000000000..aee8d7b8f
--- /dev/null
+++ b/arch/mips/boot/compressed/uart-16550.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 16550 compatible uart based serial debug support for zboot
+ */
+
+#include <linux/types.h>
+#include <linux/serial_reg.h>
+
+#include <asm/addrspace.h>
+
+#if defined(CONFIG_MACH_LOONGSON64) || defined(CONFIG_MIPS_MALTA)
+#define UART_BASE 0x1fd003f8
+#define PORT(offset) (CKSEG1ADDR(UART_BASE) + (offset))
+#endif
+
+#ifdef CONFIG_AR7
+#include <ar7.h>
+#define PORT(offset) (CKSEG1ADDR(AR7_REGS_UART0) + (4 * offset))
+#endif
+
+#ifdef CONFIG_MACH_INGENIC
+#define INGENIC_UART0_BASE_ADDR	0x10030000
+#define PORT(offset) (CKSEG1ADDR(INGENIC_UART0_BASE_ADDR) + (4 * offset))
+#endif
+
+#ifdef CONFIG_CPU_XLR
+#define UART0_BASE  0x1EF14000
+#define PORT(offset) (CKSEG1ADDR(UART0_BASE) + (4 * offset))
+#define IOTYPE unsigned int
+#endif
+
+#ifdef CONFIG_CPU_XLP
+#define UART0_BASE  0x18030100
+#define PORT(offset) (CKSEG1ADDR(UART0_BASE) + (4 * offset))
+#define IOTYPE unsigned int
+#endif
+
+#ifndef IOTYPE
+#define IOTYPE char
+#endif
+
+#ifndef PORT
+#error please define the serial port address for your own machine
+#endif
+
+static inline unsigned int serial_in(int offset)
+{
+	return *((volatile IOTYPE *)PORT(offset)) & 0xFF;
+}
+
+static inline void serial_out(int offset, int value)
+{
+	*((volatile IOTYPE *)PORT(offset)) = value & 0xFF;
+}
+
+void putc(char c)
+{
+	int timeout = 1000000;
+
+	while (((serial_in(UART_LSR) & UART_LSR_THRE) == 0) && (timeout-- > 0))
+		;
+
+	serial_out(UART_TX, c);
+}
diff --git a/arch/mips/boot/compressed/uart-alchemy.c b/arch/mips/boot/compressed/uart-alchemy.c
new file mode 100644
index 000000000..8ec63011e
--- /dev/null
+++ b/arch/mips/boot/compressed/uart-alchemy.c
@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <asm/mach-au1x00/au1000.h>
+
+void putc(char c)
+{
+	alchemy_uart_putchar(AU1000_UART0_PHYS_ADDR, c);
+}
diff --git a/arch/mips/boot/compressed/uart-prom.c b/arch/mips/boot/compressed/uart-prom.c
new file mode 100644
index 000000000..a8a0a32e0
--- /dev/null
+++ b/arch/mips/boot/compressed/uart-prom.c
@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <asm/setup.h>
+
+void putc(char c)
+{
+	prom_putchar(c);
+}