[PATCH v2 02/29] nios2: Kernel booting and initialization

Ley Foon Tan
2014-07-15T08:46:55Z

This patch adds the kernel booting and the initial setup code.

Signed-off-by: Ley Foon Tan <lftan@altera.com>
---
arch/nios2/include/asm/entry.h | 152 ++++++++++++++++++++++++++++
arch/nios2/include/asm/setup.h | 38 +++++++
arch/nios2/kernel/head.S | 175 ++++++++++++++++++++++++++++++++
arch/nios2/kernel/setup.c | 222 +++++++++++++++++++++++++++++++++++++++++
4 files changed, 587 insertions(+)
create mode 100644 arch/nios2/include/asm/entry.h
create mode 100644 arch/nios2/include/asm/setup.h
create mode 100644 arch/nios2/kernel/head.S
create mode 100644 arch/nios2/kernel/setup.c

diff --git a/arch/nios2/include/asm/entry.h b/arch/nios2/include/asm/entry.h
new file mode 100644
index 0000000..8b7cddd
--- /dev/null
+++ b/arch/nios2/include/asm/entry.h
@@ -0,0 +1,152 @@
+/*
+ * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2004 Microtronix Datacom Ltd.
+ *
+ * Based on m68knommu asm/entry.h
+ *
+ * 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.
+ */
+
+#ifndef _ASM_NIOS2_ENTRY_H
+#define _ASM_NIOS2_ENTRY_H
+
+#ifdef __ASSEMBLY__
+
+#include <asm/processor.h>
+#include <asm/registers.h>
+#include <asm/asm-offsets.h>
+
+/*
+ * Stack layout in 'ret_from_exception':
+ *
+ * This allows access to the syscall arguments in registers r4-r8
+ *
+ * 0(sp) - r8
+ * 4(sp) - r9
+ * 8(sp) - r10
+ * C(sp) - r11
+ * 10(sp) - r12
+ * 14(sp) - r13
+ * 18(sp) - r14
+ * 1C(sp) - r15
+ * 20(sp) - r1
+ * 24(sp) - r2
+ * 28(sp) - r3
+ * 2C(sp) - r4
+ * 30(sp) - r5
+ * 34(sp) - r6
+ * 38(sp) - r7
+ * 3C(sp) - orig_r2
+ * 40(sp) - ra
+ * 44(sp) - fp
+ * 48(sp) - sp
+ * 4C(sp) - gp
+ * 50(sp) - estatus
+ * 54(sp) - status_extension (NOMMU only)
+ * 58(sp) - ea
+ */
+
+/*
+ * Standard Nios2 interrupt entry and exit macros.
+ * Must be called with interrupts disabled.
+ */
+.macro SAVE_ALL
+ rdctl r24, estatus
+ andi r24, r24, ESTATUS_EU
+ beq r24, r0, 1f /* In supervisor mode, already on kernel stack */
+
+ movia r24, _current_thread /* Switch to current kernel stack */
+ ldw r24, 0(r24) /* using the thread_info */
+ addi r24, r24, THREAD_SIZE-PT_REGS_SIZE
+ stw sp, PT_SP(r24) /* Save user stack before changing */
+ mov sp, r24
+ br 2f
+
+1 : mov r24, sp
+ addi sp, sp, -PT_REGS_SIZE /* Backup the kernel stack pointer */
+ stw r24, PT_SP(sp)
+2 : stw r1, PT_R1(sp)
+ stw r2, PT_R2(sp)
+ stw r3, PT_R3(sp)
+ stw r4, PT_R4(sp)
+ stw r5, PT_R5(sp)
+ stw r6, PT_R6(sp)
+ stw r7, PT_R7(sp)
+ stw r8, PT_R8(sp)
+ stw r9, PT_R9(sp)
+ stw r10, PT_R10(sp)
+ stw r11, PT_R11(sp)
+ stw r12, PT_R12(sp)
+ stw r13, PT_R13(sp)
+ stw r14, PT_R14(sp)
+ stw r15, PT_R15(sp)
+ stw r2, PT_ORIG_R2(sp)
+ stw r7, PT_ORIG_R7(sp)
+
+ stw ra, PT_RA(sp)
+ stw fp, PT_FP(sp)
+ stw gp, PT_GP(sp)
+ rdctl r24, estatus
+ stw r24, PT_ESTATUS(sp)
+ stw ea, PT_EA(sp)
+.endm
+
+.macro RESTORE_ALL
+ ldw r1, PT_R1(sp) /* Restore registers */
+ ldw r2, PT_R2(sp)
+ ldw r3, PT_R3(sp)
+ ldw r4, PT_R4(sp)
+ ldw r5, PT_R5(sp)
+ ldw r6, PT_R6(sp)
+ ldw r7, PT_R7(sp)
+ ldw r8, PT_R8(sp)
+ ldw r9, PT_R9(sp)
+ ldw r10, PT_R10(sp)
+ ldw r11, PT_R11(sp)
+ ldw r12, PT_R12(sp)
+ ldw r13, PT_R13(sp)
+ ldw r14, PT_R14(sp)
+ ldw r15, PT_R15(sp)
+ ldw ra, PT_RA(sp)
+ ldw fp, PT_FP(sp)
+ ldw gp, PT_GP(sp)
+ ldw r24, PT_ESTATUS(sp)
+ wrctl estatus, r24
+ ldw ea, PT_EA(sp)
+ ldw sp, PT_SP(sp) /* Restore sp last */
+.endm
+
+.macro SAVE_SWITCH_STACK
+ addi sp, sp, -SWITCH_STACK_SIZE
+ stw r16, SW_R16(sp)
+ stw r17, SW_R17(sp)
+ stw r18, SW_R18(sp)
+ stw r19, SW_R19(sp)
+ stw r20, SW_R20(sp)
+ stw r21, SW_R21(sp)
+ stw r22, SW_R22(sp)
+ stw r23, SW_R23(sp)
+ stw fp, SW_FP(sp)
+ stw gp, SW_GP(sp)
+ stw ra, SW_RA(sp)
+.endm
+
+.macro RESTORE_SWITCH_STACK
+ ldw r16, SW_R16(sp)
+ ldw r17, SW_R17(sp)
+ ldw r18, SW_R18(sp)
+ ldw r19, SW_R19(sp)
+ ldw r20, SW_R20(sp)
+ ldw r21, SW_R21(sp)
+ ldw r22, SW_R22(sp)
+ ldw r23, SW_R23(sp)
+ ldw fp, SW_FP(sp)
+ ldw gp, SW_GP(sp)
+ ldw ra, SW_RA(sp)
+ addi sp, sp, SWITCH_STACK_SIZE
+.endm
+
+#endif /* __ASSEMBLY__ */
+#endif /* _ASM_NIOS2_ENTRY_H */
diff --git a/arch/nios2/include/asm/setup.h b/arch/nios2/include/asm/setup.h
new file mode 100644
index 0000000..a3e05a7
--- /dev/null
+++ b/arch/nios2/include/asm/setup.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2011 Tobias Klauser <tklauser@distanz.ch>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef _ASM_NIOS2_SETUP_H
+#define _ASM_NIOS2_SETUP_H
+
+#include <asm-generic/setup.h>
+
+#ifndef __ASSEMBLY__
+# ifdef __KERNEL__
+
+extern char exception_handler_hook[];
+extern char fast_handler[];
+extern char fast_handler_end[];
+
+extern void pagetable_init(void);
+
+extern void setup_early_printk(void);
+
+# endif/* __KERNEL__ */
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_NIOS2_SETUP_H */
diff --git a/arch/nios2/kernel/head.S b/arch/nios2/kernel/head.S
new file mode 100644
index 0000000..372ce4a
--- /dev/null
+++ b/arch/nios2/kernel/head.S
@@ -0,0 +1,175 @@
+/*
+ * Copyright (C) 2009 Wind River Systems Inc
+ * Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
+ * Copyright (C) 2004 Microtronix Datacom Ltd
+ * Copyright (C) 2001 Vic Phillips, Microtronix Datacom Ltd.
+ *
+ * Based on head.S for Altera's Excalibur development board with nios processor
+ *
+ * Based on the following from the Excalibur sdk distribution:
+ * NA_MemoryMap.s, NR_JumpToStart.s, NR_Setup.s, NR_CWPManager.s
+ *
+ * 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.
+ */
+
+#include <linux/init.h>
+#include <linux/linkage.h>
+#include <asm/thread_info.h>
+#include <asm/processor.h>
+#include <asm/cache.h>
+#include <asm/page.h>
+#include <asm/asm-offsets.h>
+#include <asm/asm-macros.h>
+
+/*
+ * ZERO_PAGE is a special page that is used for zero-initialized
+ * data and COW.
+ */
+.data
+.global empty_zero_page
+.align 12
+empty_zero_page:
+ .space PAGE_SIZE
+
+/*
+ * This global variable is used as an extension to the nios'
+ * STATUS register to emulate a user/supervisor mode.
+ */
+ .data
+ .align 2
+ .set noat
+
+ .global _current_thread
+_current_thread:
+ .long 0
+/*
+ * Input(s): passed from u-boot
+ * r4 - Optional pointer to a board information structure.
+ * r5 - Optional pointer to the physical starting address of the init RAM
+ * disk.
+ * r6 - Optional pointer to the physical ending address of the init RAM
+ * disk.
+ * r7 - Optional pointer to the physical starting address of any kernel
+ * command-line parameters.
+ */
+
+/*
+ * First executable code - detected and jumped to by the ROM bootstrap
+ * if the code resides in flash (looks for "Nios" at offset 0x0c from
+ * the potential executable image).
+ */
+ __HEAD
+ENTRY(_start)
+ wrctl status, r0 /* Disable interrupts */
+
+ /* Initialize all cache lines within the instruction cache */
+ movia r1, NIOS2_ICACHE_SIZE
+ movui r2, NIOS2_ICACHE_LINE_SIZE
+
+icache_init:
+ initi r1
+ sub r1, r1, r2
+ bgt r1, r0, icache_init
+ br 1f
+
+ /*
+ * This is the default location for the exception handler. Code in jump
+ * to our handler
+ */
+ENTRY(exception_handler_hook)
+ movia r24, inthandler
+ jmp r24
+
+ENTRY(fast_handler)
+ nextpc et
+helper:
+ stw r3, r3save - helper(et)
+
+ rdctl r3 , pteaddr
+ srli r3, r3, 12
+ slli r3, r3, 2
+ movia et, pgd_current
+
+ ldw et, 0(et)
+ add r3, et, r3
+ ldw et, 0(r3)
+
+ rdctl r3, pteaddr
+ andi r3, r3, 0xfff
+ add et, r3, et
+ ldw et, 0(et)
+ wrctl tlbacc, et
+ nextpc et
+helper2:
+ ldw r3, r3save - helper2(et)
+ subi ea, ea, 4
+ eret
+r3save:
+ .word 0x0
+ENTRY(fast_handler_end)
+
+1:
+ /*
+ * After the instruction cache is initialized, the data cache must
+ * also be initialized.
+ */
+ movia r1, NIOS2_DCACHE_SIZE
+ movui r2, NIOS2_DCACHE_LINE_SIZE
+
+dcache_init:
+ initd 0(r1)
+ sub r1, r1, r2
+ bgt r1, r0, dcache_init
+
+ nextpc r1 /* Find out where we are */
+chkadr:
+ movia r2, chkadr
+ beq r1, r2,finish_move /* We are running in RAM done */
+ addi r1, r1,(_start - chkadr) /* Source */
+ movia r2, _start /* Destination */
+ movia r3, __bss_start /* End of copy */
+
+loop_move: /* r1: src, r2: dest, r3: last dest */
+ ldw r8, 0(r1) /* load a word from [r1] */
+ stw r8, 0(r2) /* store a word to dest [r2] */
+ flushd 0(r2) /* Flush cache for safety */
+ addi r1, r1, 4 /* inc the src addr */
+ addi r2, r2, 4 /* inc the dest addr */
+ blt r2, r3, loop_move
+
+ movia r1, finish_move /* VMA(_start)->l1 */
+ jmp r1 /* jmp to _start */
+
+finish_move:
+
+ /* Mask off all possible interrupts */
+ wrctl ienable, r0
+
+ /* Clear .bss */
+ movia r2, __bss_start
+ movia r1, __bss_stop
+1:
+ stb r0, 0(r2)
+ addi r2, r2, 1
+ bne r1, r2, 1b
+
+ movia r1, init_thread_union /* set stack at top of the task union */
+ addi sp, r1, THREAD_SIZE
+ movia r2, _current_thread /* Remember current thread */
+ stw r1, 0(r2)
+
+ movia r1, nios2_boot_init /* save args r4-r7 passed from u-boot */
+ callr r1
+
+ movia r1, start_kernel /* call start_kernel as a subroutine */
+ callr r1
+
+ /* If we return from start_kernel, break to the oci debugger and
+ * buggered we are.
+ */
+ break
+
+ /* End of startup code */
+.set at
diff --git a/arch/nios2/kernel/setup.c b/arch/nios2/kernel/setup.c
new file mode 100644
index 0000000..20484ba
--- /dev/null
+++ b/arch/nios2/kernel/setup.c
@@ -0,0 +1,222 @@
+/*
+ * Nios2-specific parts of system setup
+ *
+ * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2004 Microtronix Datacom Ltd.
+ * Copyright (C) 2001 Vic Phillips <vic@microtronix.com>
+ *
+ * based on kernel/setup.c from m68knommu
+ *
+ * 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.
+ */
+
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/console.h>
+#include <linux/bootmem.h>
+#include <linux/initrd.h>
+#include <linux/of_fdt.h>
+
+#include <asm/mmu_context.h>
+#include <asm/sections.h>
+#include <asm/setup.h>
+#include <asm/cpuinfo.h>
+
+unsigned long memory_start;
+EXPORT_SYMBOL(memory_start);
+
+unsigned long memory_end;
+EXPORT_SYMBOL(memory_end);
+
+unsigned long memory_size;
+
+/* r1 r2 r3 r4 r5 r6 r7 r8 r9 r10 r11*/
+/* r12 r13 r14 r15 or2 ra fp sp gp es ste ea*/
+static struct pt_regs fake_regs = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0,
+ 0};
+
+/* Copy a short hook instruction sequence to the exception address */
+static inline void copy_exception_handler(unsigned int addr)
+{
+ unsigned int start = (unsigned int) exception_handler_hook;
+ volatile unsigned int tmp = 0;
+
+ if (start == addr) {
+ /* The CPU exception address already points to the handler. */
+ return;
+ }
+
+ __asm__ __volatile__ (
+ "ldw %2,0(%0)\n"
+ "stw %2,0(%1)\n"
+ "ldw %2,4(%0)\n"
+ "stw %2,4(%1)\n"
+ "ldw %2,8(%0)\n"
+ "stw %2,8(%1)\n"
+ "flushd 0(%1)\n"
+ "flushd 4(%1)\n"
+ "flushd 8(%1)\n"
+ "flushi %1\n"
+ "addi %1,%1,4\n"
+ "flushi %1\n"
+ "addi %1,%1,4\n"
+ "flushi %1\n"
+ "flushp\n"
+ : /* no output registers */
+ : "r" (start), "r" (addr), "r" (tmp)
+ : "memory"
+ );
+}
+
+/* Copy the fast TLB miss handler */
+static inline void copy_fast_tlb_miss_handler(unsigned int addr)
+{
+ unsigned int start = (unsigned int) fast_handler;
+ unsigned int end = (unsigned int) fast_handler_end;
+ volatile unsigned int tmp = 0;
+
+ __asm__ __volatile__ (
+ "1:\n"
+ " ldw %3,0(%0)\n"
+ " stw %3,0(%1)\n"
+ " flushd 0(%1)\n"
+ " flushi %1\n"
+ " flushp\n"
+ " addi %0,%0,4\n"
+ " addi %1,%1,4\n"
+ " bne %0,%2,1b\n"
+ : /* no output registers */
+ : "r" (start), "r" (addr), "r" (end), "r" (tmp)
+ : "memory"
+ );
+}
+
+/*
+ * save args passed from u-boot, called from head.S
+ *
+ * @r4: NIOS magic
+ * @r5: initrd start
+ * @r6: initrd end or fdt
+ * @r7: kernel command line
+ */
+asmlinkage void __init nios2_boot_init(unsigned r4, unsigned r5, unsigned r6,
+ unsigned r7)
+{
+ unsigned dtb_passed = 0;
+ char cmdline_passed[COMMAND_LINE_SIZE] = { 0, };
+
+#if defined(CONFIG_NIOS2_PASS_CMDLINE)
+ if (r4 == 0x534f494e) { /* r4 is magic NIOS */
+#if defined(CONFIG_BLK_DEV_INITRD)
+ if (r5) { /* initramfs */
+ initrd_start = r5;
+ initrd_end = r6;
+ }
+#endif /* CONFIG_BLK_DEV_INITRD */
+ dtb_passed = r6;
+
+ if (r7)
+ strncpy(cmdline_passed, (char *)r7, COMMAND_LINE_SIZE);
+ }
+#endif
+
+ early_init_devtree((void *)dtb_passed);
+
+#ifndef CONFIG_CMDLINE_FORCE
+ if (cmdline_passed[0])
+ strncpy(boot_command_line, cmdline_passed, COMMAND_LINE_SIZE);
+#ifdef CONFIG_NIOS2_CMDLINE_IGNORE_DTB
+ else
+ strncpy(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
+#endif
+#endif
+}
+
+void __init setup_arch(char **cmdline_p)
+{
+ int bootmap_size;
+
+ console_verbose();
+
+ memory_start = PAGE_ALIGN((unsigned long)__pa(_end));
+ memory_end = (unsigned long) CONFIG_NIOS2_MEM_BASE + memory_size;
+
+ init_mm.start_code = (unsigned long) _stext;
+ init_mm.end_code = (unsigned long) _etext;
+ init_mm.end_data = (unsigned long) _edata;
+ init_mm.brk = (unsigned long) _end;
+ init_task.thread.kregs = &fake_regs;
+
+ /* Keep a copy of command line */
+ *cmdline_p = boot_command_line;
+
+ min_low_pfn = PFN_UP(memory_start);
+ max_low_pfn = PFN_DOWN(memory_end);
+ max_mapnr = max_low_pfn;
+
+ /*
+ * give all the memory to the bootmap allocator, tell it to put the
+ * boot mem_map at the start of memory
+ */
+ pr_debug("init_bootmem_node(?,%#lx, %#x, %#lx)\n",
+ min_low_pfn, PFN_DOWN(PHYS_OFFSET), max_low_pfn);
+ bootmap_size = init_bootmem_node(NODE_DATA(0),
+ min_low_pfn, PFN_DOWN(PHYS_OFFSET),
+ max_low_pfn);
+
+ /*
+ * free the usable memory, we have to make sure we do not free
+ * the bootmem bitmap so we then reserve it after freeing it :-)
+ */
+ pr_debug("free_bootmem(%#lx, %#lx)\n",
+ memory_start, memory_end - memory_start);
+ free_bootmem(memory_start, memory_end - memory_start);
+
+ /*
+ * Reserve the bootmem bitmap itself as well. We do this in two
+ * steps (first step was init_bootmem()) because this catches
+ * the (very unlikely) case of us accidentally initializing the
+ * bootmem allocator with an invalid RAM area.
+ *
+ * Arguments are start, size
+ */
+ pr_debug("reserve_bootmem(%#lx, %#x)\n", memory_start, bootmap_size);
+ reserve_bootmem(memory_start, bootmap_size, BOOTMEM_DEFAULT);
+
+#ifdef CONFIG_BLK_DEV_INITRD
+ if (initrd_start) {
+ reserve_bootmem(virt_to_phys((void *)initrd_start),
+ initrd_end - initrd_start, BOOTMEM_DEFAULT);
+ }
+#endif /* CONFIG_BLK_DEV_INITRD */
+
+ unflatten_and_copy_device_tree();
+
+ setup_cpuinfo();
+
+ copy_exception_handler(cpuinfo.exception_addr);
+
+ mmu_init();
+
+ copy_fast_tlb_miss_handler(cpuinfo.fast_tlb_miss_exc_addr);
+
+ /*
+ * Initialize MMU context handling here because data from cpuinfo is
+ * needed for this.
+ */
+ mmu_context_init();
+
+ /*
+ * get kmalloc into gear
+ */
+ paging_init();
+
+#if defined(CONFIG_VT) && defined(CONFIG_DUMMY_CONSOLE)
+ conswitchp = &dummy_con;
+#endif
+}
--
1.8.2.1