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#include <linux/screen_info.h>
 23
 24#include <asm/mmu_context.h>
 25#include <asm/sections.h>
 26#include <asm/setup.h>
 27#include <asm/cpuinfo.h>
 28
 29unsigned long memory_start;
 30EXPORT_SYMBOL(memory_start);
 31
 32unsigned long memory_end;
 33EXPORT_SYMBOL(memory_end);
 34
 35static struct pt_regs fake_regs = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 36					0, 0, 0, 0, 0, 0,
 37					0};
 38
 39#ifdef CONFIG_VT
 40struct screen_info screen_info;
 41#endif
 42
 43/* Copy a short hook instruction sequence to the exception address */
 44static inline void copy_exception_handler(unsigned int addr)
 45{
 46	unsigned int start = (unsigned int) exception_handler_hook;
 47	volatile unsigned int tmp = 0;
 48
 49	if (start == addr) {
 50		/* The CPU exception address already points to the handler. */
 51		return;
 52	}
 53
 54	__asm__ __volatile__ (
 55		"ldw	%2,0(%0)\n"
 56		"stw	%2,0(%1)\n"
 57		"ldw	%2,4(%0)\n"
 58		"stw	%2,4(%1)\n"
 59		"ldw	%2,8(%0)\n"
 60		"stw	%2,8(%1)\n"
 61		"flushd	0(%1)\n"
 62		"flushd	4(%1)\n"
 63		"flushd	8(%1)\n"
 64		"flushi %1\n"
 65		"addi	%1,%1,4\n"
 66		"flushi %1\n"
 67		"addi	%1,%1,4\n"
 68		"flushi %1\n"
 69		"flushp\n"
 70		: /* no output registers */
 71		: "r" (start), "r" (addr), "r" (tmp)
 72		: "memory"
 73	);
 74}
 75
 76/* Copy the fast TLB miss handler */
 77static inline void copy_fast_tlb_miss_handler(unsigned int addr)
 78{
 79	unsigned int start = (unsigned int) fast_handler;
 80	unsigned int end = (unsigned int) fast_handler_end;
 81	volatile unsigned int tmp = 0;
 82
 83	__asm__ __volatile__ (
 84		"1:\n"
 85		"	ldw	%3,0(%0)\n"
 86		"	stw	%3,0(%1)\n"
 87		"	flushd	0(%1)\n"
 88		"	flushi	%1\n"
 89		"	flushp\n"
 90		"	addi	%0,%0,4\n"
 91		"	addi	%1,%1,4\n"
 92		"	bne	%0,%2,1b\n"
 93		: /* no output registers */
 94		: "r" (start), "r" (addr), "r" (end), "r" (tmp)
 95		: "memory"
 96	);
 97}
 98
 99/*
100 * save args passed from u-boot, called from head.S
101 *
102 * @r4: NIOS magic
103 * @r5: initrd start
104 * @r6: initrd end or fdt
105 * @r7: kernel command line
106 */
107asmlinkage void __init nios2_boot_init(unsigned r4, unsigned r5, unsigned r6,
108				       unsigned r7)
109{
110	unsigned dtb_passed = 0;
111	char cmdline_passed[COMMAND_LINE_SIZE] __maybe_unused = { 0, };
112
113#if defined(CONFIG_NIOS2_PASS_CMDLINE)
114	if (r4 == 0x534f494e) { /* r4 is magic NIOS */
115#if defined(CONFIG_BLK_DEV_INITRD)
116		if (r5) { /* initramfs */
117			initrd_start = r5;
118			initrd_end = r6;
119		}
120#endif /* CONFIG_BLK_DEV_INITRD */
121		dtb_passed = r6;
122
123		if (r7)
124			strlcpy(cmdline_passed, (char *)r7, COMMAND_LINE_SIZE);
125	}
126#endif
127
128	early_init_devtree((void *)dtb_passed);
129
130#ifndef CONFIG_CMDLINE_FORCE
131	if (cmdline_passed[0])
132		strlcpy(boot_command_line, cmdline_passed, COMMAND_LINE_SIZE);
133#ifdef CONFIG_NIOS2_CMDLINE_IGNORE_DTB
134	else
135		strlcpy(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
136#endif
137#endif
138
139	parse_early_param();
140}
141
142static void __init find_limits(unsigned long *min, unsigned long *max_low,
143			       unsigned long *max_high)
144{
145	*max_low = PFN_DOWN(memblock_get_current_limit());
146	*min = PFN_UP(memblock_start_of_DRAM());
147	*max_high = PFN_DOWN(memblock_end_of_DRAM());
148}
149
150void __init setup_arch(char **cmdline_p)
151{
152	console_verbose();
153
154	memory_start = memblock_start_of_DRAM();
155	memory_end = memblock_end_of_DRAM();
156
157	setup_initial_init_mm(_stext, _etext, _edata, _end);
158	init_task.thread.kregs = &fake_regs;
159
160	/* Keep a copy of command line */
161	*cmdline_p = boot_command_line;
162
163	find_limits(&min_low_pfn, &max_low_pfn, &max_pfn);
164	max_mapnr = max_low_pfn;
165
166	memblock_reserve(__pa_symbol(_stext), _end - _stext);
167#ifdef CONFIG_BLK_DEV_INITRD
168	if (initrd_start) {
169		memblock_reserve(virt_to_phys((void *)initrd_start),
170				initrd_end - initrd_start);
171	}
172#endif /* CONFIG_BLK_DEV_INITRD */
173
174	early_init_fdt_reserve_self();
175	early_init_fdt_scan_reserved_mem();
176
177	unflatten_and_copy_device_tree();
178
179	setup_cpuinfo();
180
181	copy_exception_handler(cpuinfo.exception_addr);
182
183	mmu_init();
184
185	copy_fast_tlb_miss_handler(cpuinfo.fast_tlb_miss_exc_addr);
186
187	/*
188	 * Initialize MMU context handling here because data from cpuinfo is
189	 * needed for this.
190	 */
191	mmu_context_init();
192
193	/*
194	 * get kmalloc into gear
195	 */
196	paging_init();
197}