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+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * head.S - Common startup code for 68000 core based CPU's
+ *
+ * 2012.10.21, Luis Alves <ljalvs@gmail.com>, Single head.S file for all
+ * 68000 core based CPU's. Based on the sources from:
+ * Coldfire by Greg Ungerer <gerg@snapgear.com>
+ * 68328 by D. Jeff Dionne <jeff@ryeham.ee.ryerson.ca>,
+ * Kenneth Albanowski <kjahds@kjahds.com>,
+ * The Silver Hammer Group, Ltd.
+ *
+ */
+
+#include <linux/linkage.h>
+#include <linux/init.h>
+#include <asm/asm-offsets.h>
+#include <asm/thread_info.h>
+
+
+/*****************************************************************************
+ * UCSIMM and UCDIMM use CONFIG_MEMORY_RESERVE to reserve some RAM
+ *****************************************************************************/
+#ifdef CONFIG_MEMORY_RESERVE
+#define RAMEND (CONFIG_RAMBASE+CONFIG_RAMSIZE)-(CONFIG_MEMORY_RESERVE*0x100000)
+#else
+#define RAMEND (CONFIG_RAMBASE+CONFIG_RAMSIZE)
+#endif
+/*****************************************************************************/
+
+.global _start
+.global _rambase
+.global _ramvec
+.global _ramstart
+.global _ramend
+
+#if defined(CONFIG_PILOT) || defined(CONFIG_INIT_LCD)
+.global bootlogo_bits
+#endif
+
+/* Defining DEBUG_HEAD_CODE, serial port in 68x328 is inited */
+/* #define DEBUG_HEAD_CODE */
+#undef DEBUG_HEAD_CODE
+
+.data
+
+/*****************************************************************************
+ * RAM setup pointers. Used by the kernel to determine RAM location and size.
+ *****************************************************************************/
+
+_rambase:
+ .long 0
+_ramvec:
+ .long 0
+_ramstart:
+ .long 0
+_ramend:
+ .long 0
+
+__HEAD
+
+/*****************************************************************************
+ * Entry point, where all begins!
+ *****************************************************************************/
+
+_start:
+
+/* Pilot need this specific signature at the start of ROM */
+#ifdef CONFIG_PILOT
+ .byte 0x4e, 0xfa, 0x00, 0x0a /* bra opcode (jmp 10 bytes) */
+ .byte 'b', 'o', 'o', 't'
+ .word 10000
+ nop
+ moveq #0, %d0
+ movew %d0, 0xfffff618 /* Watchdog off */
+ movel #0x00011f07, 0xfffff114 /* CS A1 Mask */
+#endif /* CONFIG_PILOT */
+
+ movew #0x2700, %sr /* disable all interrupts */
+
+/*****************************************************************************
+ * Setup PLL and wait for it to settle (in 68x328 cpu's).
+ * Also, if enabled, init serial port.
+ *****************************************************************************/
+#if defined(CONFIG_M68328) || \
+ defined(CONFIG_M68EZ328) || \
+ defined(CONFIG_M68VZ328)
+
+/* Serial port setup. Should only be needed if debugging this startup code. */
+#ifdef DEBUG_HEAD_CODE
+ movew #0x0800, 0xfffff906 /* Ignore CTS */
+ movew #0x010b, 0xfffff902 /* BAUD to 9600 */
+ movew #0xe100, 0xfffff900 /* enable */
+#endif /* DEBUG_HEAD */
+
+#ifdef CONFIG_PILOT
+ movew #0x2410, 0xfffff200 /* PLLCR */
+#else
+ movew #0x2400, 0xfffff200 /* PLLCR */
+#endif
+ movew #0x0123, 0xfffff202 /* PLLFSR */
+ moveq #0, %d0
+ movew #16384, %d0 /* PLL settle wait loop */
+_pll_settle:
+ subw #1, %d0
+ bne _pll_settle
+#endif /* CONFIG_M68x328 */
+
+
+/*****************************************************************************
+ * If running kernel from ROM some specific initialization has to be done.
+ * (Assuming that everything is already init'ed when running from RAM)
+ *****************************************************************************/
+#ifdef CONFIG_ROMKERNEL
+
+/*****************************************************************************
+ * Init chip registers (uCsimm specific)
+ *****************************************************************************/
+#ifdef CONFIG_UCSIMM
+ moveb #0x00, 0xfffffb0b /* Watchdog off */
+ moveb #0x10, 0xfffff000 /* SCR */
+ moveb #0x00, 0xfffff40b /* enable chip select */
+ moveb #0x00, 0xfffff423 /* enable /DWE */
+ moveb #0x08, 0xfffffd0d /* disable hardmap */
+ moveb #0x07, 0xfffffd0e /* level 7 interrupt clear */
+ movew #0x8600, 0xfffff100 /* FLASH at 0x10c00000 */
+ movew #0x018b, 0xfffff110 /* 2Meg, enable, 0ws */
+ movew #0x8f00, 0xfffffc00 /* DRAM configuration */
+ movew #0x9667, 0xfffffc02 /* DRAM control */
+ movew #0x0000, 0xfffff106 /* DRAM at 0x00000000 */
+ movew #0x068f, 0xfffff116 /* 8Meg, enable, 0ws */
+ moveb #0x40, 0xfffff300 /* IVR */
+ movel #0x007FFFFF, %d0 /* IMR */
+ movel %d0, 0xfffff304
+ moveb 0xfffff42b, %d0
+ andb #0xe0, %d0
+ moveb %d0, 0xfffff42b
+#endif
+
+/*****************************************************************************
+ * Init LCD controller.
+ * (Assuming that LCD controller is already init'ed when running from RAM)
+ *****************************************************************************/
+#ifdef CONFIG_INIT_LCD
+#ifdef CONFIG_PILOT
+ moveb #0, 0xfffffA27 /* LCKCON */
+ movel #_start, 0xfffffA00 /* LSSA */
+ moveb #0xa, 0xfffffA05 /* LVPW */
+ movew #0x9f, 0xFFFFFa08 /* LXMAX */
+ movew #0x9f, 0xFFFFFa0a /* LYMAX */
+ moveb #9, 0xfffffa29 /* LBAR */
+ moveb #0, 0xfffffa25 /* LPXCD */
+ moveb #0x04, 0xFFFFFa20 /* LPICF */
+ moveb #0x58, 0xfffffA27 /* LCKCON */
+ moveb #0x85, 0xfffff429 /* PFDATA */
+ moveb #0xd8, 0xfffffA27 /* LCKCON */
+ moveb #0xc5, 0xfffff429 /* PFDATA */
+ moveb #0xd5, 0xfffff429 /* PFDATA */
+ movel #bootlogo_bits, 0xFFFFFA00 /* LSSA */
+ moveb #10, 0xFFFFFA05 /* LVPW */
+ movew #160, 0xFFFFFA08 /* LXMAX */
+ movew #160, 0xFFFFFA0A /* LYMAX */
+#else /* CONFIG_PILOT */
+ movel #bootlogo_bits, 0xfffffA00 /* LSSA */
+ moveb #0x28, 0xfffffA05 /* LVPW */
+ movew #0x280, 0xFFFFFa08 /* LXMAX */
+ movew #0x1df, 0xFFFFFa0a /* LYMAX */
+ moveb #0, 0xfffffa29 /* LBAR */
+ moveb #0, 0xfffffa25 /* LPXCD */
+ moveb #0x08, 0xFFFFFa20 /* LPICF */
+ moveb #0x01, 0xFFFFFA21 /* -ve pol */
+ moveb #0x81, 0xfffffA27 /* LCKCON */
+ movew #0xff00, 0xfffff412 /* LCD pins */
+#endif /* CONFIG_PILOT */
+#endif /* CONFIG_INIT_LCD */
+
+/*****************************************************************************
+ * Kernel is running from FLASH/ROM (XIP)
+ * Copy init text & data to RAM
+ *****************************************************************************/
+ moveal #_etext, %a0
+ moveal #_sdata, %a1
+ moveal #__bss_start, %a2
+_copy_initmem:
+ movel %a0@+, %a1@+
+ cmpal %a1, %a2
+ bhi _copy_initmem
+#endif /* CONFIG_ROMKERNEL */
+
+/*****************************************************************************
+ * Setup basic memory information for kernel
+ *****************************************************************************/
+ movel #CONFIG_VECTORBASE,_ramvec /* set vector base location */
+ movel #CONFIG_RAMBASE,_rambase /* set the base of RAM */
+ movel #RAMEND, _ramend /* set end ram addr */
+ lea __bss_stop,%a1
+ movel %a1,_ramstart
+
+/*****************************************************************************
+ * If the kernel is in RAM, move romfs to right above bss and
+ * adjust _ramstart to where romfs ends.
+ *
+ * (Do this only if CONFIG_MTD_UCLINUX is true)
+ *****************************************************************************/
+
+#if defined(CONFIG_ROMFS_FS) && defined(CONFIG_RAMKERNEL) && \
+ defined(CONFIG_MTD_UCLINUX)
+ lea __bss_start, %a0 /* get start of bss */
+ lea __bss_stop, %a1 /* set up destination */
+ movel %a0, %a2 /* copy of bss start */
+
+ movel 8(%a0), %d0 /* get size of ROMFS */
+ addql #8, %d0 /* allow for rounding */
+ andl #0xfffffffc, %d0 /* whole words */
+
+ addl %d0, %a0 /* copy from end */
+ addl %d0, %a1 /* copy from end */
+ movel %a1, _ramstart /* set start of ram */
+_copy_romfs:
+ movel -(%a0), -(%a1) /* copy dword */
+ cmpl %a0, %a2 /* check if at end */
+ bne _copy_romfs
+#endif /* CONFIG_ROMFS_FS && CONFIG_RAMKERNEL && CONFIG_MTD_UCLINUX */
+
+/*****************************************************************************
+ * Clear bss region
+ *****************************************************************************/
+ lea __bss_start, %a0 /* get start of bss */
+ lea __bss_stop, %a1 /* get end of bss */
+_clear_bss:
+ movel #0, (%a0)+ /* clear each word */
+ cmpl %a0, %a1 /* check if at end */
+ bne _clear_bss
+
+/*****************************************************************************
+ * Load the current task pointer and stack.
+ *****************************************************************************/
+ lea init_thread_union,%a0
+ lea THREAD_SIZE(%a0),%sp
+ jsr start_kernel /* start Linux kernel */
+_exit:
+ jmp _exit /* should never get here */