1/*
  2 * Nios2-specific parts of system setup
  3 *
  4 * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
  5 * Copyright (C) 2004 Microtronix Datacom Ltd.
  6 * Copyright (C) 2001 Vic Phillips <vic@microtronix.com>
  7 *
  8 * This file is subject to the terms and conditions of the GNU General Public
  9 * License. See the file "COPYING" in the main directory of this archive
 10 * for more details.
 11 */
 12
 13#include <linux/export.h>
 14#include <linux/kernel.h>
 15#include <linux/mm.h>
 16#include <linux/sched.h>
 17#include <linux/sched/task.h>
 18#include <linux/console.h>
 19#include <linux/memblock.h>
 20#include <linux/initrd.h>
 21#include <linux/of_fdt.h>
 22
 23#include <asm/mmu_context.h>
 24#include <asm/sections.h>
 25#include <asm/setup.h>
 26#include <asm/cpuinfo.h>
 27
 28unsigned long memory_start;
 29EXPORT_SYMBOL(memory_start);
 30
 31unsigned long memory_end;
 32EXPORT_SYMBOL(memory_end);
 33
 34static struct pt_regs fake_regs = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 35					0, 0, 0, 0, 0, 0,
 36					0};
 37
 38/* Copy a short hook instruction sequence to the exception address */
 39static inline void copy_exception_handler(unsigned int addr)
 40{
 41	unsigned int start = (unsigned int) exception_handler_hook;
 42	volatile unsigned int tmp = 0;
 43
 44	if (start == addr) {
 45		/* The CPU exception address already points to the handler. */
 46		return;
 47	}
 48
 49	__asm__ __volatile__ (
 50		"ldw	%2,0(%0)\n"
 51		"stw	%2,0(%1)\n"
 52		"ldw	%2,4(%0)\n"
 53		"stw	%2,4(%1)\n"
 54		"ldw	%2,8(%0)\n"
 55		"stw	%2,8(%1)\n"
 56		"flushd	0(%1)\n"
 57		"flushd	4(%1)\n"
 58		"flushd	8(%1)\n"
 59		"flushi %1\n"
 60		"addi	%1,%1,4\n"
 61		"flushi %1\n"
 62		"addi	%1,%1,4\n"
 63		"flushi %1\n"
 64		"flushp\n"
 65		: /* no output registers */
 66		: "r" (start), "r" (addr), "r" (tmp)
 67		: "memory"
 68	);
 69}
 70
 71/* Copy the fast TLB miss handler */
 72static inline void copy_fast_tlb_miss_handler(unsigned int addr)
 73{
 74	unsigned int start = (unsigned int) fast_handler;
 75	unsigned int end = (unsigned int) fast_handler_end;
 76	volatile unsigned int tmp = 0;
 77
 78	__asm__ __volatile__ (
 79		"1:\n"
 80		"	ldw	%3,0(%0)\n"
 81		"	stw	%3,0(%1)\n"
 82		"	flushd	0(%1)\n"
 83		"	flushi	%1\n"
 84		"	flushp\n"
 85		"	addi	%0,%0,4\n"
 86		"	addi	%1,%1,4\n"
 87		"	bne	%0,%2,1b\n"
 88		: /* no output registers */
 89		: "r" (start), "r" (addr), "r" (end), "r" (tmp)
 90		: "memory"
 91	);
 92}
 93
 94/*
 95 * save args passed from u-boot, called from head.S
 96 *
 97 * @r4: NIOS magic
 98 * @r5: initrd start
 99 * @r6: initrd end or fdt
100 * @r7: kernel command line
101 */
102asmlinkage void __init nios2_boot_init(unsigned r4, unsigned r5, unsigned r6,
103				       unsigned r7)
104{
105	unsigned dtb_passed = 0;
106	char cmdline_passed[COMMAND_LINE_SIZE] __maybe_unused = { 0, };
107
108#if defined(CONFIG_NIOS2_PASS_CMDLINE)
109	if (r4 == 0x534f494e) { /* r4 is magic NIOS */
110#if defined(CONFIG_BLK_DEV_INITRD)
111		if (r5) { /* initramfs */
112			initrd_start = r5;
113			initrd_end = r6;
114		}
115#endif /* CONFIG_BLK_DEV_INITRD */
116		dtb_passed = r6;
117
118		if (r7)
119			strscpy(cmdline_passed, (char *)r7, COMMAND_LINE_SIZE);
120	}
121#endif
122
123	early_init_devtree((void *)dtb_passed);
124
125#ifndef CONFIG_CMDLINE_FORCE
126	if (cmdline_passed[0])
127		strscpy(boot_command_line, cmdline_passed, COMMAND_LINE_SIZE);
128#ifdef CONFIG_NIOS2_CMDLINE_IGNORE_DTB
129	else
130		strscpy(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
131#endif
132#endif
133
134	parse_early_param();
135}
136
137static void __init find_limits(unsigned long *min, unsigned long *max_low,
138			       unsigned long *max_high)
139{
140	*max_low = PFN_DOWN(memblock_get_current_limit());
141	*min = PFN_UP(memblock_start_of_DRAM());
142	*max_high = PFN_DOWN(memblock_end_of_DRAM());
143}
144
145void __init setup_arch(char **cmdline_p)
146{
147	console_verbose();
148
149	memory_start = memblock_start_of_DRAM();
150	memory_end = memblock_end_of_DRAM();
151
152	setup_initial_init_mm(_stext, _etext, _edata, _end);
153	init_task.thread.kregs = &fake_regs;
154
155	/* Keep a copy of command line */
156	*cmdline_p = boot_command_line;
157
158	find_limits(&min_low_pfn, &max_low_pfn, &max_pfn);
159	max_mapnr = max_low_pfn;
160
161	memblock_reserve(__pa_symbol(_stext), _end - _stext);
162#ifdef CONFIG_BLK_DEV_INITRD
163	if (initrd_start) {
164		memblock_reserve(virt_to_phys((void *)initrd_start),
165				initrd_end - initrd_start);
166	}
167#endif /* CONFIG_BLK_DEV_INITRD */
168
169	early_init_fdt_reserve_self();
170	early_init_fdt_scan_reserved_mem();
171
172	unflatten_and_copy_device_tree();
173
174	setup_cpuinfo();
175
176	copy_exception_handler(cpuinfo.exception_addr);
177
178	mmu_init();
179
180	copy_fast_tlb_miss_handler(cpuinfo.fast_tlb_miss_exc_addr);
181
182	/*
183	 * Initialize MMU context handling here because data from cpuinfo is
184	 * needed for this.
185	 */
186	mmu_context_init();
187
188	/*
189	 * get kmalloc into gear
190	 */
191	paging_init();
192}