mips: mtmips: add support for MediaTek MT7621 SoC
This patch adds support for MediaTek MT7621 SoC.
All files are dedicated for u-boot.
The default build target is u-boot-mt7621.bin.
The specification of this chip:
https://www.mediatek.com/products/homenetworking/mt7621
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
diff --git a/arch/mips/mach-mtmips/mt7621/tpl/start.S b/arch/mips/mach-mtmips/mt7621/tpl/start.S
new file mode 100644
index 0000000..19b09f7
--- /dev/null
+++ b/arch/mips/mach-mtmips/mt7621/tpl/start.S
@@ -0,0 +1,161 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2022 MediaTek Inc. All rights reserved.
+ *
+ * Author: Weijie Gao <weijie.gao@mediatek.com>
+ */
+
+#include <asm-offsets.h>
+#include <config.h>
+#include <asm/asm.h>
+#include <asm/regdef.h>
+#include <asm/addrspace.h>
+#include <asm/mipsregs.h>
+#include <asm/cm.h>
+#include "../mt7621.h"
+
+#define SP_ADDR_TEMP 0xbe10dff0
+
+ .set noreorder
+
+ .macro init_wr sel
+ MTC0 zero, CP0_WATCHLO,\sel
+ mtc0 t1, CP0_WATCHHI,\sel
+ .endm
+
+ .macro uhi_mips_exception
+ move k0, t9 # preserve t9 in k0
+ move k1, a0 # preserve a0 in k1
+ li t9, 15 # UHI exception operation
+ li a0, 0 # Use hard register context
+ sdbbp 1 # Invoke UHI operation
+ .endm
+
+ENTRY(_start)
+ b reset
+ mtc0 zero, CP0_COUNT
+
+ /*
+ * Store TPL size here.
+ * This will be used by SPL to locate u-boot payload.
+ */
+ .org TPL_INFO_OFFSET
+ .word TPL_INFO_MAGIC
+ .word __image_copy_len
+
+ /* Exception vector */
+ .org 0x200
+ /* TLB refill, 32 bit task */
+ uhi_mips_exception
+
+ .org 0x280
+ /* XTLB refill, 64 bit task */
+ uhi_mips_exception
+
+ .org 0x300
+ /* Cache error exception */
+ uhi_mips_exception
+
+ .org 0x380
+ /* General exception */
+ uhi_mips_exception
+
+ .org 0x400
+ /* Catch interrupt exceptions */
+ uhi_mips_exception
+
+ .org 0x480
+ /* EJTAG debug exception */
+1: b 1b
+ nop
+
+ .org 0x500
+
+reset:
+ /* Set KSEG0 to Uncached */
+ mfc0 t0, CP0_CONFIG
+ ins t0, zero, 0, 3
+ ori t0, t0, CONF_CM_UNCACHED
+ mtc0 t0, CP0_CONFIG
+ ehb
+
+ /* Check for CPU number */
+ mfc0 t0, CP0_EBASE
+ and t0, t0, MIPS_EBASE_CPUNUM
+ beqz t0, 1f
+ nop
+
+ /* Secondary core goes to specified SPL entry address */
+ li t0, KSEG1ADDR(SYSCTL_BASE)
+ lw t0, BOOT_SRAM_BASE_REG(t0)
+ jr t0
+ nop
+
+ /* Init CP0 Status */
+1: mfc0 t0, CP0_STATUS
+ and t0, ST0_IMPL
+ or t0, ST0_BEV | ST0_ERL
+ mtc0 t0, CP0_STATUS
+ nop
+
+ /* Clear Watch Status bits and disable watch exceptions */
+ li t1, 0x7 # Clear I, R and W conditions
+ init_wr 0
+ init_wr 1
+ init_wr 2
+ init_wr 3
+
+ /* Clear WP, IV and SW interrupts */
+ mtc0 zero, CP0_CAUSE
+
+ /* Clear timer interrupt (CP0_COUNT cleared on branch to 'reset') */
+ mtc0 zero, CP0_COMPARE
+
+ /* Setup basic CPS */
+ bal mips_cm_map
+ nop
+
+ li t0, KSEG1ADDR(CONFIG_MIPS_CM_BASE)
+ li t1, GCR_REG0_BASE_VALUE
+ sw t1, GCR_REG0_BASE(t0)
+
+ li t1, ((GCR_REG0_MASK_VALUE << GCR_REGn_MASK_ADDRMASK_SHIFT) | \
+ GCR_REGn_MASK_CMTGT_IOCU0)
+ sw t1, GCR_REG0_MASK(t0)
+
+ lw t1, GCR_BASE(t0)
+ ins t1, zero, 0, 2 # CM_DEFAULT_TARGET
+ sw t1, GCR_BASE(t0)
+
+ lw t1, GCR_CONTROL(t0)
+ li t2, GCR_CONTROL_SYNCCTL
+ or t1, t1, t2
+ sw t1, GCR_CONTROL(t0)
+
+ /* Increase SPI frequency */
+ li t0, KSEG1ADDR(SPI_BASE)
+ li t1, 5
+ sw t1, SPI_SPACE_REG(t0)
+
+ /* Set CPU clock to 500MHz */
+ li t0, KSEG1ADDR(SYSCTL_BASE)
+ lw t1, SYSCTL_CLKCFG0_REG(t0)
+ ins t1, zero, 30, 2 # CPU_CLK_SEL
+ sw t1, SYSCTL_CLKCFG0_REG(t0)
+
+ /* Set CPU clock divider to 1/1 */
+ li t0, KSEG1ADDR(RBUS_BASE)
+ li t1, 0x101
+ sw t1, RBUS_DYN_CFG0_REG(t0)
+
+ /* Initialize the SRAM */
+ bal mips_sram_init
+ nop
+
+ /* Set up initial stack */
+ li sp, SP_ADDR_TEMP
+
+ bal tpl_main
+ nop
+
+ END(_start)