1 /* 2 * Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu> 3 * Copyright (C) 2007-2009 PetaLogix 4 * Copyright (C) 2006 Atmark Techno, Inc. 5 * 6 * MMU code derived from arch/ppc/kernel/head_4xx.S: 7 * Copyright (c) 1995-1996 Gary Thomas <gdt@linuxppc.org> 8 * Initial PowerPC version. 9 * Copyright (c) 1996 Cort Dougan <cort@cs.nmt.edu> 10 * Rewritten for PReP 11 * Copyright (c) 1996 Paul Mackerras <paulus@cs.anu.edu.au> 12 * Low-level exception handers, MMU support, and rewrite. 13 * Copyright (c) 1997 Dan Malek <dmalek@jlc.net> 14 * PowerPC 8xx modifications. 15 * Copyright (c) 1998-1999 TiVo, Inc. 16 * PowerPC 403GCX modifications. 17 * Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu> 18 * PowerPC 403GCX/405GP modifications. 19 * Copyright 2000 MontaVista Software Inc. 20 * PPC405 modifications 21 * PowerPC 403GCX/405GP modifications. 22 * Author: MontaVista Software, Inc. 23 * frank_rowand@mvista.com or source@mvista.com 24 * debbie_chu@mvista.com 25 * 26 * This file is subject to the terms and conditions of the GNU General Public 27 * License. See the file "COPYING" in the main directory of this archive 28 * for more details. 29 */ 30 31 #include <linux/init.h> 32 #include <linux/linkage.h> 33 #include <asm/thread_info.h> 34 #include <asm/page.h> 35 #include <linux/of_fdt.h> /* for OF_DT_HEADER */ 36 37 #ifdef CONFIG_MMU 38 #include <asm/setup.h> /* COMMAND_LINE_SIZE */ 39 #include <asm/mmu.h> 40 #include <asm/processor.h> 41 42 .section .data 43 .global empty_zero_page 44 .align 12 45 empty_zero_page: 46 .space PAGE_SIZE 47 .global swapper_pg_dir 48 swapper_pg_dir: 49 .space PAGE_SIZE 50 51 #endif /* CONFIG_MMU */ 52 53 .section .rodata 54 .align 4 55 endian_check: 56 .word 1 57 58 __HEAD 59 ENTRY(_start) 60 #if CONFIG_KERNEL_BASE_ADDR == 0 61 brai TOPHYS(real_start) 62 .org 0x100 63 real_start: 64 #endif 65 66 mts rmsr, r0 67 /* Disable stack protection from bootloader */ 68 mts rslr, r0 69 addi r8, r0, 0xFFFFFFFF 70 mts rshr, r8 71 /* 72 * According to Xilinx, msrclr instruction behaves like 'mfs rX,rpc' 73 * if the msrclr instruction is not enabled. We use this to detect 74 * if the opcode is available, by issuing msrclr and then testing the result. 75 * r8 == 0 - msr instructions are implemented 76 * r8 != 0 - msr instructions are not implemented 77 */ 78 mfs r1, rmsr 79 msrclr r8, 0 /* clear nothing - just read msr for test */ 80 cmpu r8, r8, r1 /* r1 must contain msr reg content */ 81 82 /* r7 may point to an FDT, or there may be one linked in. 83 if it's in r7, we've got to save it away ASAP. 84 We ensure r7 points to a valid FDT, just in case the bootloader 85 is broken or non-existent */ 86 beqi r7, no_fdt_arg /* NULL pointer? don't copy */ 87 /* Does r7 point to a valid FDT? Load HEADER magic number */ 88 /* Run time Big/Little endian platform */ 89 /* Save 1 as word and load byte - 0 - BIG, 1 - LITTLE */ 90 lbui r11, r0, TOPHYS(endian_check) 91 beqid r11, big_endian /* DO NOT break delay stop dependency */ 92 lw r11, r0, r7 /* Big endian load in delay slot */ 93 lwr r11, r0, r7 /* Little endian load */ 94 big_endian: 95 rsubi r11, r11, OF_DT_HEADER /* Check FDT header */ 96 beqi r11, _prepare_copy_fdt 97 or r7, r0, r0 /* clear R7 when not valid DTB */ 98 bnei r11, no_fdt_arg /* No - get out of here */ 99 _prepare_copy_fdt: 100 or r11, r0, r0 /* incremment */ 101 ori r4, r0, TOPHYS(_fdt_start) 102 ori r3, r0, (0x8000 - 4) 103 _copy_fdt: 104 lw r12, r7, r11 /* r12 = r7 + r11 */ 105 sw r12, r4, r11 /* addr[r4 + r11] = r12 */ 106 addik r11, r11, 4 /* increment counting */ 107 bgtid r3, _copy_fdt /* loop for all entries */ 108 addik r3, r3, -4 /* descrement loop */ 109 no_fdt_arg: 110 111 #ifdef CONFIG_MMU 112 113 #ifndef CONFIG_CMDLINE_BOOL 114 /* 115 * handling command line 116 * copy command line directly to cmd_line placed in data section. 117 */ 118 beqid r5, skip /* Skip if NULL pointer */ 119 or r11, r0, r0 /* incremment */ 120 ori r4, r0, cmd_line /* load address of command line */ 121 tophys(r4,r4) /* convert to phys address */ 122 ori r3, r0, COMMAND_LINE_SIZE - 1 /* number of loops */ 123 _copy_command_line: 124 /* r2=r5+r6 - r5 contain pointer to command line */ 125 lbu r2, r5, r11 126 beqid r2, skip /* Skip if no data */ 127 sb r2, r4, r11 /* addr[r4+r6]= r2 */ 128 addik r11, r11, 1 /* increment counting */ 129 bgtid r3, _copy_command_line /* loop for all entries */ 130 addik r3, r3, -1 /* decrement loop */ 131 addik r5, r4, 0 /* add new space for command line */ 132 tovirt(r5,r5) 133 skip: 134 #endif /* CONFIG_CMDLINE_BOOL */ 135 136 #ifdef NOT_COMPILE 137 /* save bram context */ 138 or r11, r0, r0 /* incremment */ 139 ori r4, r0, TOPHYS(_bram_load_start) /* save bram context */ 140 ori r3, r0, (LMB_SIZE - 4) 141 _copy_bram: 142 lw r7, r0, r11 /* r7 = r0 + r6 */ 143 sw r7, r4, r11 /* addr[r4 + r6] = r7 */ 144 addik r11, r11, 4 /* increment counting */ 145 bgtid r3, _copy_bram /* loop for all entries */ 146 addik r3, r3, -4 /* descrement loop */ 147 #endif 148 /* We have to turn on the MMU right away. */ 149 150 /* 151 * Set up the initial MMU state so we can do the first level of 152 * kernel initialization. This maps the first 16 MBytes of memory 1:1 153 * virtual to physical. 154 */ 155 nop 156 addik r3, r0, MICROBLAZE_TLB_SIZE -1 /* Invalidate all TLB entries */ 157 _invalidate: 158 mts rtlbx, r3 159 mts rtlbhi, r0 /* flush: ensure V is clear */ 160 mts rtlblo, r0 161 bgtid r3, _invalidate /* loop for all entries */ 162 addik r3, r3, -1 163 /* sync */ 164 165 /* Setup the kernel PID */ 166 mts rpid,r0 /* Load the kernel PID */ 167 nop 168 bri 4 169 170 /* 171 * We should still be executing code at physical address area 172 * RAM_BASEADDR at this point. However, kernel code is at 173 * a virtual address. So, set up a TLB mapping to cover this once 174 * translation is enabled. 175 */ 176 177 addik r3,r0, CONFIG_KERNEL_START /* Load the kernel virtual address */ 178 tophys(r4,r3) /* Load the kernel physical address */ 179 180 /* start to do TLB calculation */ 181 addik r12, r0, _end 182 rsub r12, r3, r12 183 addik r12, r12, CONFIG_LOWMEM_SIZE >> PTE_SHIFT /* that's the pad */ 184 185 or r9, r0, r0 /* TLB0 = 0 */ 186 or r10, r0, r0 /* TLB1 = 0 */ 187 188 addik r11, r12, -0x1000000 189 bgei r11, GT16 /* size is greater than 16MB */ 190 addik r11, r12, -0x0800000 191 bgei r11, GT8 /* size is greater than 8MB */ 192 addik r11, r12, -0x0400000 193 bgei r11, GT4 /* size is greater than 4MB */ 194 /* size is less than 4MB */ 195 addik r11, r12, -0x0200000 196 bgei r11, GT2 /* size is greater than 2MB */ 197 addik r9, r0, 0x0100000 /* TLB0 must be 1MB */ 198 addik r11, r12, -0x0100000 199 bgei r11, GT1 /* size is greater than 1MB */ 200 /* TLB1 is 0 which is setup above */ 201 bri tlb_end 202 GT4: /* r11 contains the rest - will be either 1 or 4 */ 203 ori r9, r0, 0x400000 /* TLB0 is 4MB */ 204 bri TLB1 205 GT16: /* TLB0 is 16MB */ 206 addik r9, r0, 0x1000000 /* means TLB0 is 16MB */ 207 TLB1: 208 /* must be used r2 because of subtract if failed */ 209 addik r2, r11, -0x0400000 210 bgei r2, GT20 /* size is greater than 16MB */ 211 /* size is >16MB and <20MB */ 212 addik r11, r11, -0x0100000 213 bgei r11, GT17 /* size is greater than 17MB */ 214 /* kernel is >16MB and < 17MB */ 215 GT1: 216 addik r10, r0, 0x0100000 /* means TLB1 is 1MB */ 217 bri tlb_end 218 GT2: /* TLB0 is 0 and TLB1 will be 4MB */ 219 GT17: /* TLB1 is 4MB - kernel size <20MB */ 220 addik r10, r0, 0x0400000 /* means TLB1 is 4MB */ 221 bri tlb_end 222 GT8: /* TLB0 is still zero that's why I can use only TLB1 */ 223 GT20: /* TLB1 is 16MB - kernel size >20MB */ 224 addik r10, r0, 0x1000000 /* means TLB1 is 16MB */ 225 tlb_end: 226 227 /* 228 * Configure and load two entries into TLB slots 0 and 1. 229 * In case we are pinning TLBs, these are reserved in by the 230 * other TLB functions. If not reserving, then it doesn't 231 * matter where they are loaded. 232 */ 233 andi r4,r4,0xfffffc00 /* Mask off the real page number */ 234 ori r4,r4,(TLB_WR | TLB_EX) /* Set the write and execute bits */ 235 236 /* 237 * TLB0 is always used - check if is not zero (r9 stores TLB0 value) 238 * if is use TLB1 value and clear it (r10 stores TLB1 value) 239 */ 240 bnei r9, tlb0_not_zero 241 add r9, r10, r0 242 add r10, r0, r0 243 tlb0_not_zero: 244 245 /* look at the code below */ 246 ori r30, r0, 0x200 247 andi r29, r9, 0x100000 248 bneid r29, 1f 249 addik r30, r30, 0x80 250 andi r29, r9, 0x400000 251 bneid r29, 1f 252 addik r30, r30, 0x80 253 andi r29, r9, 0x1000000 254 bneid r29, 1f 255 addik r30, r30, 0x80 256 1: 257 andi r3,r3,0xfffffc00 /* Mask off the effective page number */ 258 ori r3,r3,(TLB_VALID) 259 or r3, r3, r30 260 261 /* Load tlb_skip size value which is index to first unused TLB entry */ 262 lwi r11, r0, TOPHYS(tlb_skip) 263 mts rtlbx,r11 /* TLB slow 0 */ 264 265 mts rtlblo,r4 /* Load the data portion of the entry */ 266 mts rtlbhi,r3 /* Load the tag portion of the entry */ 267 268 /* Increase tlb_skip size */ 269 addik r11, r11, 1 270 swi r11, r0, TOPHYS(tlb_skip) 271 272 /* TLB1 can be zeroes that's why we not setup it */ 273 beqi r10, jump_over2 274 275 /* look at the code below */ 276 ori r30, r0, 0x200 277 andi r29, r10, 0x100000 278 bneid r29, 1f 279 addik r30, r30, 0x80 280 andi r29, r10, 0x400000 281 bneid r29, 1f 282 addik r30, r30, 0x80 283 andi r29, r10, 0x1000000 284 bneid r29, 1f 285 addik r30, r30, 0x80 286 1: 287 addk r4, r4, r9 /* previous addr + TLB0 size */ 288 addk r3, r3, r9 289 290 andi r3,r3,0xfffffc00 /* Mask off the effective page number */ 291 ori r3,r3,(TLB_VALID) 292 or r3, r3, r30 293 294 lwi r11, r0, TOPHYS(tlb_skip) 295 mts rtlbx, r11 /* r11 is used from TLB0 */ 296 297 mts rtlblo,r4 /* Load the data portion of the entry */ 298 mts rtlbhi,r3 /* Load the tag portion of the entry */ 299 300 /* Increase tlb_skip size */ 301 addik r11, r11, 1 302 swi r11, r0, TOPHYS(tlb_skip) 303 304 jump_over2: 305 /* 306 * Load a TLB entry for LMB, since we need access to 307 * the exception vectors, using a 4k real==virtual mapping. 308 */ 309 /* Use temporary TLB_ID for LMB - clear this temporary mapping later */ 310 ori r11, r0, MICROBLAZE_LMB_TLB_ID 311 mts rtlbx,r11 312 313 ori r4,r0,(TLB_WR | TLB_EX) 314 ori r3,r0,(TLB_VALID | TLB_PAGESZ(PAGESZ_4K)) 315 316 mts rtlblo,r4 /* Load the data portion of the entry */ 317 mts rtlbhi,r3 /* Load the tag portion of the entry */ 318 319 /* 320 * We now have the lower 16 Meg of RAM mapped into TLB entries, and the 321 * caches ready to work. 322 */ 323 turn_on_mmu: 324 ori r15,r0,start_here 325 ori r4,r0,MSR_KERNEL_VMS 326 mts rmsr,r4 327 nop 328 rted r15,0 /* enables MMU */ 329 nop 330 331 start_here: 332 #endif /* CONFIG_MMU */ 333 334 /* Initialize small data anchors */ 335 addik r13, r0, _KERNEL_SDA_BASE_ 336 addik r2, r0, _KERNEL_SDA2_BASE_ 337 338 /* Initialize stack pointer */ 339 addik r1, r0, init_thread_union + THREAD_SIZE - 4 340 341 /* Initialize r31 with current task address */ 342 addik r31, r0, init_task 343 344 addik r11, r0, machine_early_init 345 brald r15, r11 346 nop 347 348 #ifndef CONFIG_MMU 349 addik r15, r0, machine_halt 350 braid start_kernel 351 nop 352 #else 353 /* 354 * Initialize the MMU. 355 */ 356 bralid r15, mmu_init 357 nop 358 359 /* Go back to running unmapped so we can load up new values 360 * and change to using our exception vectors. 361 * On the MicroBlaze, all we invalidate the used TLB entries to clear 362 * the old 16M byte TLB mappings. 363 */ 364 ori r15,r0,TOPHYS(kernel_load_context) 365 ori r4,r0,MSR_KERNEL 366 mts rmsr,r4 367 nop 368 bri 4 369 rted r15,0 370 nop 371 372 /* Load up the kernel context */ 373 kernel_load_context: 374 ori r5, r0, MICROBLAZE_LMB_TLB_ID 375 mts rtlbx,r5 376 nop 377 mts rtlbhi,r0 378 nop 379 addi r15, r0, machine_halt 380 ori r17, r0, start_kernel 381 ori r4, r0, MSR_KERNEL_VMS 382 mts rmsr, r4 383 nop 384 rted r17, 0 /* enable MMU and jump to start_kernel */ 385 nop 386 #endif /* CONFIG_MMU */