target/linux/ubicom32/files/arch/ubicom32/kernel/head.S

   1 /*
   2  * arch/ubicom32/kernel/head.S
   3  *      <TODO: Replace with short file description>
   4  *
   5  * (C) Copyright 2009, Ubicom, Inc.
   6  *
   7  * This file is part of the Ubicom32 Linux Kernel Port.
   8  *
   9  * The Ubicom32 Linux Kernel Port is free software: you can redistribute
  10  * it and/or modify it under the terms of the GNU General Public License
  11  * as published by the Free Software Foundation, either version 2 of the
  12  * License, or (at your option) any later version.
  13  *
  14  * The Ubicom32 Linux Kernel Port is distributed in the hope that it
  15  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  16  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  17  * the GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with the Ubicom32 Linux Kernel Port.  If not,
  21  * see <http://www.gnu.org/licenses/>.
  22  *
  23  * Ubicom32 implementation derived from (with many thanks):
  24  *   arch/m68knommu
  25  *   arch/blackfin
  26  *   arch/parisc
  27  */
  28 #include <linux/sys.h>
  29 #include <linux/linkage.h>
  30 #include <asm/asm-offsets.h>
  31 #include <asm/page_offset.h>
  32 #define __ASM__
  33 #include <asm/ip5000.h>
  34
  35
  36 #define SRC_AN A3
  37 #define DST_AN A4
  38
  39 #define PARAM_DN D0
  40 #define TMP_DN D15
  41 #define TMP2_DN D14
  42
  43 /*
  44  * The following code is placed at the start of the Linux section of memory.
  45  * This is the primary entry point for Linux.
  46  *
  47  * However, we also want the syscall entry/exit code to be at a fixed address.
  48  * So we take the primary entry point and reserve 16 bytes.  That address is
  49  * where the system_call entry point exists.  This 16 bytes basically allows
  50  * us to jump around the system_call entry point code to the actual startup
  51  * code.
  52  *
  53  * Linux Memory Map (see vlinux.lds.S):
  54  * 0x40400000 - Primary Entry Point for Linux (jump around code below).
  55  * 0x40400010 - Old syscall Entry Point.
  56  */
  57
  58         .sect   .skip_syscall, "ax", @progbits
  59         .global __skip_syscall_section
  60 __skip_syscall_section:
  61         moveai          A3, #%hi(_start)
  62         lea.1           A3, %lo(_start)(A3)
  63         ret             A3
  64 /*
  65  * __os_node_offset contains the offset from KERNELBASE to the os_node, it is
  66  * not intended to be used by anything except the boot code.
  67  */
  68 __os_node_offset:
  69 .long   (_os_node - KERNELSTART)
  70
  71 .text
  72 .global _start
  73
  74 /*
  75  * start()
  76  *      This is the start of the Linux kernel.
  77  */
  78 _start:
  79         move.4          SCRATCHPAD1, #0
  80
  81
  82 /*
  83  * Setup the range registers... the loader has setup a few, but we will go ahead
  84  * and correct them for our own limits. Note that once set these are never
  85  * changed again.  The ranges are as follows
  86  *
  87  *  D_RANGE0 - io block (set up by loaded)
  88  *
  89  *  I_RANGE0 and D_RANGE1 - kernel/ultra loader address space bottom of ocm-> top
  90  *      of ram typically 0x3ffc0000 - 0x440000000
  91  *  I_RANGE1 - kernel / userspace transition area (aka syscalls, context switches)
  92  *      typically 0x3FFC0030 - ~0x3FFC0200
  93  *  I_RANGE2 / D_RANGE2 - slab area
  94  *      typically 0x40A00000 - ~0x44000000
  95  *  I_RANGE3
  96  *      old system call interface if enabled.
  97  *
  98  *   D_RANGE3, D_RANGE4 - unused.
  99  */
 100         moveai          SRC_AN, #%hi(PAGE_OFFSET_RAW)
 101         lea.4           SRC_AN, %lo(PAGE_OFFSET_RAW)(SRC_AN)
 102         move.4          D_RANGE1_LO, SRC_AN
 103         move.4          I_RANGE0_LO, SRC_AN
 104
 105 ; don't try to calculate I_RANGE_HI, see below
 106 ;       moveai          SRC_AN, #%hi(___init_end-4)
 107 ;       lea.4           SRC_AN, %lo(___init_end-4)(SRC_AN)
 108 ;       move.4          I_RANGE0_HI, SRC_AN
 109
 110         moveai          SRC_AN, #%hi(SDRAMSTART + CONFIG_MIN_RAMSIZE-4)
 111         lea.4           SRC_AN, %lo(SDRAMSTART + CONFIG_MIN_RAMSIZE-4)(SRC_AN)
 112         move.4          D_RANGE1_HI, SRC_AN
 113
 114 ; for now allow the whole ram to be executable as well so we don't run into problems
 115 ; once we load user more code.
 116         move.4          I_RANGE0_HI, SRC_AN
 117
 118 #ifdef CONFIG_PROTECT_KERNEL
 119 ; when kernel protection is enabled, we only open up syscall and non kernel text
 120 ; for userspace apps, for now only irange registers registers 1 and 2 are used for userspace.
 121
 122         ;; syscall range
 123         moveai          SRC_AN, #%hi(__syscall_text_run_begin)
 124         lea.4           SRC_AN, %lo(__syscall_text_run_begin)(SRC_AN)
 125         move.4          I_RANGE1_LO, SRC_AN
 126         moveai          SRC_AN, #%hi(__syscall_text_run_end)
 127         lea.4           SRC_AN, %lo(__syscall_text_run_end)(SRC_AN)
 128         move.4          I_RANGE1_HI, SRC_AN
 129
 130         ;; slab instructions
 131         moveai          SRC_AN, #%hi(_edata)
 132         lea.4           SRC_AN, %lo(_edata)(SRC_AN)
 133         move.4          I_RANGE2_LO, SRC_AN
 134         ;; End of DDR is already in range0 hi so just copy it.
 135         move.4          I_RANGE2_HI, I_RANGE0_HI
 136
 137 #ifdef CONFIG_OLD_40400010_SYSTEM_CALL
 138         ;; create a small hole for old syscall location
 139         moveai          SRC_AN, #%hi(0x40400000)
 140         lea.4           I_RANGE3_LO, 0x10(SRC_AN)
 141         lea.4           I_RANGE3_HI, 0x14(SRC_AN)
 142 #endif
 143         ;; slab data (same as slab instructions but starting a little earlier).
 144         moveai          SRC_AN, #%hi(_data_protection_end)
 145         lea.4           SRC_AN, %lo(_data_protection_end)(SRC_AN)
 146         move.4          D_RANGE2_LO, SRC_AN
 147         move.4          D_RANGE2_HI, I_RANGE0_HI
 148
 149 ;; enable ranges
 150         ;; skip I_RANGE0_EN
 151         move.4          I_RANGE1_EN, #-1
 152         move.4          I_RANGE2_EN, #-1
 153 #ifdef CONFIG_OLD_40400010_SYSTEM_CALL
 154         move.4          I_RANGE3_EN, #-1
 155 #else
 156         move.4          I_RANGE3_EN, #0
 157 #endif
 158         ;; skip D_RANGE0_EN or D_RANGE1_EN
 159         move.4          D_RANGE2_EN, #-1
 160         move.4          D_RANGE3_EN, #0
 161         move.4          D_RANGE4_EN, #0
 162 #endif
 163
 164 ;
 165 ; If __ocm_free_begin is smaller than __ocm_free_end the
 166 ; setup OCM text and data ram banks properly
 167 ;
 168         moveai          DST_AN, #%hi(__ocm_free_begin)
 169         lea.4           TMP_DN, %lo(__ocm_free_begin)(DST_AN)
 170         moveai          DST_AN, #%hi(__ocm_free_end)
 171         lea.4           TMP2_DN, %lo(__ocm_free_end)(DST_AN)
 172         sub.4           #0, TMP2_DN, TMP_DN
 173         jmple.f         2f
 174         moveai          DST_AN, #%hi(__data_begin)
 175         lea.4           TMP_DN, %lo(__data_begin)(DST_AN)
 176         moveai          DST_AN, #%hi(OCMSTART)
 177         lea.4           TMP2_DN, %lo(OCMSTART)(DST_AN)
 178         sub.4           TMP_DN, TMP_DN, TMP2_DN
 179         lsr.4           TMP_DN, TMP_DN, #15
 180         lsl.4           TMP_DN, #1, TMP_DN
 181         moveai          DST_AN, #%hi(OCMC_BASE)
 182         add.4           OCMC_BANK_MASK(DST_AN), #-1, TMP_DN
 183         pipe_flush      0
 184 2:
 185 ;
 186 ; Load .ocm_text
 187 ;
 188         moveai          DST_AN, #%hi(__ocm_text_run_end)
 189         lea.4           TMP_DN, %lo(__ocm_text_run_end)(DST_AN)
 190         moveai          DST_AN, #%hi(__ocm_text_run_begin)
 191         lea.4           DST_AN, %lo(__ocm_text_run_begin)(DST_AN)
 192         moveai          SRC_AN, #%hi(__ocm_text_load_begin)
 193         lea.4           SRC_AN, %lo(__ocm_text_load_begin)(SRC_AN)
 194         jmpt.t          2f
 195
 196 1:      move.4          (DST_AN)4++, (SRC_AN)4++
 197
 198 2:      sub.4           #0, DST_AN, TMP_DN
 199         jmpne.t         1b
 200 ;
 201 ; Load .syscall_text
 202 ;
 203         moveai          DST_AN, #%hi(__syscall_text_run_end)
 204         lea.4           TMP_DN, %lo(__syscall_text_run_end)(DST_AN)
 205         moveai          DST_AN, #%hi(__syscall_text_run_begin)
 206         lea.4           DST_AN, %lo(__syscall_text_run_begin)(DST_AN)
 207         moveai          SRC_AN, #%hi(__syscall_text_load_begin)
 208         lea.4           SRC_AN, %lo(__syscall_text_load_begin)(SRC_AN)
 209         jmpt.t          2f
 210
 211 1:      move.4          (DST_AN)4++, (SRC_AN)4++
 212
 213 2:      sub.4           #0, DST_AN, TMP_DN
 214         jmpne.t         1b
 215
 216 ;
 217 ; Load .ocm_data
 218 ;
 219         moveai          DST_AN, #%hi(__ocm_data_run_end)
 220         lea.4           TMP_DN, %lo(__ocm_data_run_end)(DST_AN)
 221         moveai          DST_AN, #%hi(__ocm_data_run_begin)
 222         lea.4           DST_AN, %lo(__ocm_data_run_begin)(DST_AN)
 223         moveai          SRC_AN, #%hi(__ocm_data_load_begin)
 224         lea.4           SRC_AN, %lo(__ocm_data_load_begin)(SRC_AN)
 225         jmpt.t          2f
 226
 227 1:      move.4          (DST_AN)4++, (SRC_AN)4++
 228
 229 2:      sub.4           #0, DST_AN, TMP_DN
 230         jmpne.t         1b
 231
 232 ; Clear .bss
 233 ;
 234         moveai          SRC_AN, #%hi(_ebss)
 235         lea.4           TMP_DN, %lo(_ebss)(SRC_AN)
 236         moveai          DST_AN, #%hi(_sbss)
 237         lea.4           DST_AN, %lo(_sbss)(DST_AN)
 238         jmpt.t          2f
 239
 240 1:      move.4          (DST_AN)4++, #0
 241
 242 2:      sub.4           #0, DST_AN, TMP_DN
 243         jmpne.t         1b
 244
 245 ; save our parameter to devtree (after clearing .bss)
 246         moveai          DST_AN, #%hi(devtree)
 247         lea.4           DST_AN, %lo(devtree)(DST_AN)
 248         move.4          (DST_AN), PARAM_DN
 249
 250         moveai          sp, #%hi(init_thread_union)
 251         lea.4           sp, %lo(init_thread_union)(sp)
 252         movei           TMP_DN, #ASM_THREAD_SIZE
 253         add.4           sp, sp, TMP_DN
 254         move.4          -4(sp)++, #0 ; nesting level = 0
 255         move.4          -4(sp)++, #1 ; KERNEL_THREAD
 256
 257 ;; ip3k-elf-gdb backend now sets scratchpad3 to 1 when either continue
 258 ;; or single step commands are issued. scratchpad3 is set to 0 when the
 259 ;; debugger detaches from the board.
 260         move.4          TMP_DN, scratchpad3
 261         lsl.4           TMP_DN, TMP_DN, #0x0
 262         jmpeq.f         _jump_to_start_kernel
 263 _ok_to_set_break_points_in_linux:
 264 ;; THREAD_STALL
 265         move.4          mt_dbg_active_clr,#-1
 266 ;; stalling the threads isn't instantaneous.. need to flush the pipe.
 267         pipe_flush      0
 268         pipe_flush      0
 269
 270 _jump_to_start_kernel:
 271         moveai          SRC_AN, #%hi(start_kernel)
 272         lea.4           SRC_AN, %lo(start_kernel)(SRC_AN)
 273         ret             SRC_AN