xref: /openbmc/linux/arch/arc/kernel/setup.c (revision 55fd7e02) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
4  */
5 
6 #include <linux/seq_file.h>
7 #include <linux/fs.h>
8 #include <linux/delay.h>
9 #include <linux/root_dev.h>
10 #include <linux/clk.h>
11 #include <linux/clocksource.h>
12 #include <linux/console.h>
13 #include <linux/module.h>
14 #include <linux/sizes.h>
15 #include <linux/cpu.h>
16 #include <linux/of_clk.h>
17 #include <linux/of_fdt.h>
18 #include <linux/of.h>
19 #include <linux/cache.h>
20 #include <uapi/linux/mount.h>
21 #include <asm/sections.h>
22 #include <asm/arcregs.h>
23 #include <asm/asserts.h>
24 #include <asm/tlb.h>
25 #include <asm/setup.h>
26 #include <asm/page.h>
27 #include <asm/irq.h>
28 #include <asm/unwind.h>
29 #include <asm/mach_desc.h>
30 #include <asm/smp.h>
31 #include <asm/dsp-impl.h>
32 
33 #define FIX_PTR(x)  __asm__ __volatile__(";" : "+r"(x))
34 
35 unsigned int intr_to_DE_cnt;
36 
37 /* Part of U-boot ABI: see head.S */
38 int __initdata uboot_tag;
39 int __initdata uboot_magic;
40 char __initdata *uboot_arg;
41 
42 const struct machine_desc *machine_desc;
43 
44 struct task_struct *_current_task[NR_CPUS];	/* For stack switching */
45 
46 struct cpuinfo_arc cpuinfo_arc700[NR_CPUS];
47 
48 static const struct id_to_str arc_legacy_rel[] = {
49 	/* ID.ARCVER,	Release */
50 #ifdef CONFIG_ISA_ARCOMPACT
51 	{ 0x34, 	"R4.10"},
52 	{ 0x35, 	"R4.11"},
53 #else
54 	{ 0x51, 	"R2.0" },
55 	{ 0x52, 	"R2.1" },
56 	{ 0x53,		"R3.0" },
57 #endif
58 	{ 0x00,		NULL   }
59 };
60 
61 static const struct id_to_str arc_cpu_rel[] = {
62 	/* UARCH.MAJOR,	Release */
63 	{  0,		"R3.10a"},
64 	{  1,		"R3.50a"},
65 	{  0xFF,	NULL   }
66 };
67 
68 static void read_decode_ccm_bcr(struct cpuinfo_arc *cpu)
69 {
70 	if (is_isa_arcompact()) {
71 		struct bcr_iccm_arcompact iccm;
72 		struct bcr_dccm_arcompact dccm;
73 
74 		READ_BCR(ARC_REG_ICCM_BUILD, iccm);
75 		if (iccm.ver) {
76 			cpu->iccm.sz = 4096 << iccm.sz;	/* 8K to 512K */
77 			cpu->iccm.base_addr = iccm.base << 16;
78 		}
79 
80 		READ_BCR(ARC_REG_DCCM_BUILD, dccm);
81 		if (dccm.ver) {
82 			unsigned long base;
83 			cpu->dccm.sz = 2048 << dccm.sz;	/* 2K to 256K */
84 
85 			base = read_aux_reg(ARC_REG_DCCM_BASE_BUILD);
86 			cpu->dccm.base_addr = base & ~0xF;
87 		}
88 	} else {
89 		struct bcr_iccm_arcv2 iccm;
90 		struct bcr_dccm_arcv2 dccm;
91 		unsigned long region;
92 
93 		READ_BCR(ARC_REG_ICCM_BUILD, iccm);
94 		if (iccm.ver) {
95 			cpu->iccm.sz = 256 << iccm.sz00;	/* 512B to 16M */
96 			if (iccm.sz00 == 0xF && iccm.sz01 > 0)
97 				cpu->iccm.sz <<= iccm.sz01;
98 
99 			region = read_aux_reg(ARC_REG_AUX_ICCM);
100 			cpu->iccm.base_addr = region & 0xF0000000;
101 		}
102 
103 		READ_BCR(ARC_REG_DCCM_BUILD, dccm);
104 		if (dccm.ver) {
105 			cpu->dccm.sz = 256 << dccm.sz0;
106 			if (dccm.sz0 == 0xF && dccm.sz1 > 0)
107 				cpu->dccm.sz <<= dccm.sz1;
108 
109 			region = read_aux_reg(ARC_REG_AUX_DCCM);
110 			cpu->dccm.base_addr = region & 0xF0000000;
111 		}
112 	}
113 }
114 
115 static void decode_arc_core(struct cpuinfo_arc *cpu)
116 {
117 	struct bcr_uarch_build_arcv2 uarch;
118 	const struct id_to_str *tbl;
119 
120 	/*
121 	 * Up until (including) the first core4 release (0x54) things were
122 	 * simple: AUX IDENTITY.ARCVER was sufficient to identify arc family
123 	 * and release: 0x50 to 0x53 was HS38, 0x54 was HS48 (dual issue)
124 	 */
125 
126 	if (cpu->core.family < 0x54) { /* includes arc700 */
127 
128 		for (tbl = &arc_legacy_rel[0]; tbl->id != 0; tbl++) {
129 			if (cpu->core.family == tbl->id) {
130 				cpu->release = tbl->str;
131 				break;
132 			}
133 		}
134 
135 		if (is_isa_arcompact())
136 			cpu->name = "ARC700";
137 		else if (tbl->str)
138 			cpu->name = "HS38";
139 		else
140 			cpu->name = cpu->release = "Unknown";
141 
142 		return;
143 	}
144 
145 	/*
146 	 * However the subsequent HS release (same 0x54) allow HS38 or HS48
147 	 * configurations and encode this info in a different BCR.
148 	 * The BCR was introduced in 0x54 so can't be read unconditionally.
149 	 */
150 
151 	READ_BCR(ARC_REG_MICRO_ARCH_BCR, uarch);
152 
153 	if (uarch.prod == 4) {
154 		cpu->name = "HS48";
155 		cpu->extn.dual = 1;
156 
157 	} else {
158 		cpu->name = "HS38";
159 	}
160 
161 	for (tbl = &arc_cpu_rel[0]; tbl->id != 0xFF; tbl++) {
162 		if (uarch.maj == tbl->id) {
163 			cpu->release = tbl->str;
164 			break;
165 		}
166 	}
167 }
168 
169 static void read_arc_build_cfg_regs(void)
170 {
171 	struct bcr_timer timer;
172 	struct bcr_generic bcr;
173 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()];
174 	struct bcr_isa_arcv2 isa;
175 	struct bcr_actionpoint ap;
176 
177 	FIX_PTR(cpu);
178 
179 	READ_BCR(AUX_IDENTITY, cpu->core);
180 	decode_arc_core(cpu);
181 
182 	READ_BCR(ARC_REG_TIMERS_BCR, timer);
183 	cpu->extn.timer0 = timer.t0;
184 	cpu->extn.timer1 = timer.t1;
185 	cpu->extn.rtc = timer.rtc;
186 
187 	cpu->vec_base = read_aux_reg(AUX_INTR_VEC_BASE);
188 
189 	READ_BCR(ARC_REG_MUL_BCR, cpu->extn_mpy);
190 
191 	/* Read CCM BCRs for boot reporting even if not enabled in Kconfig */
192 	read_decode_ccm_bcr(cpu);
193 
194 	read_decode_mmu_bcr();
195 	read_decode_cache_bcr();
196 
197 	if (is_isa_arcompact()) {
198 		struct bcr_fp_arcompact sp, dp;
199 		struct bcr_bpu_arcompact bpu;
200 
201 		READ_BCR(ARC_REG_FP_BCR, sp);
202 		READ_BCR(ARC_REG_DPFP_BCR, dp);
203 		cpu->extn.fpu_sp = sp.ver ? 1 : 0;
204 		cpu->extn.fpu_dp = dp.ver ? 1 : 0;
205 
206 		READ_BCR(ARC_REG_BPU_BCR, bpu);
207 		cpu->bpu.ver = bpu.ver;
208 		cpu->bpu.full = bpu.fam ? 1 : 0;
209 		if (bpu.ent) {
210 			cpu->bpu.num_cache = 256 << (bpu.ent - 1);
211 			cpu->bpu.num_pred = 256 << (bpu.ent - 1);
212 		}
213 	} else {
214 		struct bcr_fp_arcv2 spdp;
215 		struct bcr_bpu_arcv2 bpu;
216 
217 		READ_BCR(ARC_REG_FP_V2_BCR, spdp);
218 		cpu->extn.fpu_sp = spdp.sp ? 1 : 0;
219 		cpu->extn.fpu_dp = spdp.dp ? 1 : 0;
220 
221 		READ_BCR(ARC_REG_BPU_BCR, bpu);
222 		cpu->bpu.ver = bpu.ver;
223 		cpu->bpu.full = bpu.ft;
224 		cpu->bpu.num_cache = 256 << bpu.bce;
225 		cpu->bpu.num_pred = 2048 << bpu.pte;
226 		cpu->bpu.ret_stk = 4 << bpu.rse;
227 
228 		/* if dual issue hardware, is it enabled ? */
229 		if (cpu->extn.dual) {
230 			unsigned int exec_ctrl;
231 
232 			READ_BCR(AUX_EXEC_CTRL, exec_ctrl);
233 			cpu->extn.dual_enb = !(exec_ctrl & 1);
234 		}
235 	}
236 
237 	READ_BCR(ARC_REG_AP_BCR, ap);
238 	if (ap.ver) {
239 		cpu->extn.ap_num = 2 << ap.num;
240 		cpu->extn.ap_full = !ap.min;
241 	}
242 
243 	READ_BCR(ARC_REG_SMART_BCR, bcr);
244 	cpu->extn.smart = bcr.ver ? 1 : 0;
245 
246 	READ_BCR(ARC_REG_RTT_BCR, bcr);
247 	cpu->extn.rtt = bcr.ver ? 1 : 0;
248 
249 	READ_BCR(ARC_REG_ISA_CFG_BCR, isa);
250 
251 	/* some hacks for lack of feature BCR info in old ARC700 cores */
252 	if (is_isa_arcompact()) {
253 		if (!isa.ver)	/* ISA BCR absent, use Kconfig info */
254 			cpu->isa.atomic = IS_ENABLED(CONFIG_ARC_HAS_LLSC);
255 		else {
256 			/* ARC700_BUILD only has 2 bits of isa info */
257 			struct bcr_generic bcr = *(struct bcr_generic *)&isa;
258 			cpu->isa.atomic = bcr.info & 1;
259 		}
260 
261 		cpu->isa.be = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
262 
263 		 /* there's no direct way to distinguish 750 vs. 770 */
264 		if (unlikely(cpu->core.family < 0x34 || cpu->mmu.ver < 3))
265 			cpu->name = "ARC750";
266 	} else {
267 		cpu->isa = isa;
268 	}
269 }
270 
271 static char *arc_cpu_mumbojumbo(int cpu_id, char *buf, int len)
272 {
273 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[cpu_id];
274 	struct bcr_identity *core = &cpu->core;
275 	char mpy_opt[16];
276 	int n = 0;
277 
278 	FIX_PTR(cpu);
279 
280 	n += scnprintf(buf + n, len - n,
281 		       "\nIDENTITY\t: ARCVER [%#02x] ARCNUM [%#02x] CHIPID [%#4x]\n",
282 		       core->family, core->cpu_id, core->chip_id);
283 
284 	n += scnprintf(buf + n, len - n, "processor [%d]\t: %s %s (%s ISA) %s%s%s\n",
285 		       cpu_id, cpu->name, cpu->release,
286 		       is_isa_arcompact() ? "ARCompact" : "ARCv2",
287 		       IS_AVAIL1(cpu->isa.be, "[Big-Endian]"),
288 		       IS_AVAIL3(cpu->extn.dual, cpu->extn.dual_enb, " Dual-Issue "));
289 
290 	n += scnprintf(buf + n, len - n, "Timers\t\t: %s%s%s%s%s%s\nISA Extn\t: ",
291 		       IS_AVAIL1(cpu->extn.timer0, "Timer0 "),
292 		       IS_AVAIL1(cpu->extn.timer1, "Timer1 "),
293 		       IS_AVAIL2(cpu->extn.rtc, "RTC [UP 64-bit] ", CONFIG_ARC_TIMERS_64BIT),
294 		       IS_AVAIL2(cpu->extn.gfrc, "GFRC [SMP 64-bit] ", CONFIG_ARC_TIMERS_64BIT));
295 
296 	if (cpu->extn_mpy.ver) {
297 		if (is_isa_arcompact()) {
298 			scnprintf(mpy_opt, 16, "mpy");
299 		} else {
300 
301 			int opt = 2;	/* stock MPY/MPYH */
302 
303 			if (cpu->extn_mpy.dsp)	/* OPT 7-9 */
304 				opt = cpu->extn_mpy.dsp + 6;
305 
306 			scnprintf(mpy_opt, 16, "mpy[opt %d] ", opt);
307 		}
308 	}
309 
310 	n += scnprintf(buf + n, len - n, "%s%s%s%s%s%s%s%s\n",
311 		       IS_AVAIL2(cpu->isa.atomic, "atomic ", CONFIG_ARC_HAS_LLSC),
312 		       IS_AVAIL2(cpu->isa.ldd, "ll64 ", CONFIG_ARC_HAS_LL64),
313 		       IS_AVAIL2(cpu->isa.unalign, "unalign ", CONFIG_ARC_USE_UNALIGNED_MEM_ACCESS),
314 		       IS_AVAIL1(cpu->extn_mpy.ver, mpy_opt),
315 		       IS_AVAIL1(cpu->isa.div_rem, "div_rem "));
316 
317 	if (cpu->bpu.ver) {
318 		n += scnprintf(buf + n, len - n,
319 			      "BPU\t\t: %s%s match, cache:%d, Predict Table:%d Return stk: %d",
320 			      IS_AVAIL1(cpu->bpu.full, "full"),
321 			      IS_AVAIL1(!cpu->bpu.full, "partial"),
322 			      cpu->bpu.num_cache, cpu->bpu.num_pred, cpu->bpu.ret_stk);
323 
324 		if (is_isa_arcv2()) {
325 			struct bcr_lpb lpb;
326 
327 			READ_BCR(ARC_REG_LPB_BUILD, lpb);
328 			if (lpb.ver) {
329 				unsigned int ctl;
330 				ctl = read_aux_reg(ARC_REG_LPB_CTRL);
331 
332 				n += scnprintf(buf + n, len - n, " Loop Buffer:%d %s",
333 					       lpb.entries,
334 					       IS_DISABLED_RUN(!ctl));
335 			}
336 		}
337 		n += scnprintf(buf + n, len - n, "\n");
338 	}
339 
340 	return buf;
341 }
342 
343 static char *arc_extn_mumbojumbo(int cpu_id, char *buf, int len)
344 {
345 	int n = 0;
346 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[cpu_id];
347 
348 	FIX_PTR(cpu);
349 
350 	n += scnprintf(buf + n, len - n, "Vector Table\t: %#x\n", cpu->vec_base);
351 
352 	if (cpu->extn.fpu_sp || cpu->extn.fpu_dp)
353 		n += scnprintf(buf + n, len - n, "FPU\t\t: %s%s\n",
354 			       IS_AVAIL1(cpu->extn.fpu_sp, "SP "),
355 			       IS_AVAIL1(cpu->extn.fpu_dp, "DP "));
356 
357 	if (cpu->extn.ap_num | cpu->extn.smart | cpu->extn.rtt) {
358 		n += scnprintf(buf + n, len - n, "DEBUG\t\t: %s%s",
359 			       IS_AVAIL1(cpu->extn.smart, "smaRT "),
360 			       IS_AVAIL1(cpu->extn.rtt, "RTT "));
361 		if (cpu->extn.ap_num) {
362 			n += scnprintf(buf + n, len - n, "ActionPoint %d/%s",
363 				       cpu->extn.ap_num,
364 				       cpu->extn.ap_full ? "full":"min");
365 		}
366 		n += scnprintf(buf + n, len - n, "\n");
367 	}
368 
369 	if (cpu->dccm.sz || cpu->iccm.sz)
370 		n += scnprintf(buf + n, len - n, "Extn [CCM]\t: DCCM @ %x, %d KB / ICCM: @ %x, %d KB\n",
371 			       cpu->dccm.base_addr, TO_KB(cpu->dccm.sz),
372 			       cpu->iccm.base_addr, TO_KB(cpu->iccm.sz));
373 
374 	if (is_isa_arcv2()) {
375 
376 		/* Error Protection: ECC/Parity */
377 		struct bcr_erp erp;
378 		READ_BCR(ARC_REG_ERP_BUILD, erp);
379 
380 		if (erp.ver) {
381 			struct  ctl_erp ctl;
382 			READ_BCR(ARC_REG_ERP_CTRL, ctl);
383 
384 			/* inverted bits: 0 means enabled */
385 			n += scnprintf(buf + n, len - n, "Extn [ECC]\t: %s%s%s%s%s%s\n",
386 				IS_AVAIL3(erp.ic,  !ctl.dpi, "IC "),
387 				IS_AVAIL3(erp.dc,  !ctl.dpd, "DC "),
388 				IS_AVAIL3(erp.mmu, !ctl.mpd, "MMU "));
389 		}
390 	}
391 
392 	return buf;
393 }
394 
395 void chk_opt_strict(char *opt_name, bool hw_exists, bool opt_ena)
396 {
397 	if (hw_exists && !opt_ena)
398 		pr_warn(" ! Enable %s for working apps\n", opt_name);
399 	else if (!hw_exists && opt_ena)
400 		panic("Disable %s, hardware NOT present\n", opt_name);
401 }
402 
403 void chk_opt_weak(char *opt_name, bool hw_exists, bool opt_ena)
404 {
405 	if (!hw_exists && opt_ena)
406 		panic("Disable %s, hardware NOT present\n", opt_name);
407 }
408 
409 static void arc_chk_core_config(void)
410 {
411 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()];
412 	int present = 0;
413 
414 	if (!cpu->extn.timer0)
415 		panic("Timer0 is not present!\n");
416 
417 	if (!cpu->extn.timer1)
418 		panic("Timer1 is not present!\n");
419 
420 #ifdef CONFIG_ARC_HAS_DCCM
421 	/*
422 	 * DCCM can be arbit placed in hardware.
423 	 * Make sure it's placement/sz matches what Linux is built with
424 	 */
425 	if ((unsigned int)__arc_dccm_base != cpu->dccm.base_addr)
426 		panic("Linux built with incorrect DCCM Base address\n");
427 
428 	if (CONFIG_ARC_DCCM_SZ * SZ_1K != cpu->dccm.sz)
429 		panic("Linux built with incorrect DCCM Size\n");
430 #endif
431 
432 #ifdef CONFIG_ARC_HAS_ICCM
433 	if (CONFIG_ARC_ICCM_SZ * SZ_1K != cpu->iccm.sz)
434 		panic("Linux built with incorrect ICCM Size\n");
435 #endif
436 
437 	/*
438 	 * FP hardware/software config sanity
439 	 * -If hardware present, kernel needs to save/restore FPU state
440 	 * -If not, it will crash trying to save/restore the non-existant regs
441 	 */
442 
443 	if (is_isa_arcompact()) {
444 		/* only DPDP checked since SP has no arch visible regs */
445 		present = cpu->extn.fpu_dp;
446 		CHK_OPT_STRICT(CONFIG_ARC_FPU_SAVE_RESTORE, present);
447 	} else {
448 		/* Accumulator Low:High pair (r58:59) present if DSP MPY or FPU */
449 		present = cpu->extn_mpy.dsp | cpu->extn.fpu_sp | cpu->extn.fpu_dp;
450 		CHK_OPT_STRICT(CONFIG_ARC_HAS_ACCL_REGS, present);
451 
452 		dsp_config_check();
453 	}
454 }
455 
456 /*
457  * Initialize and setup the processor core
458  * This is called by all the CPUs thus should not do special case stuff
459  *    such as only for boot CPU etc
460  */
461 
462 void setup_processor(void)
463 {
464 	char str[512];
465 	int cpu_id = smp_processor_id();
466 
467 	read_arc_build_cfg_regs();
468 	arc_init_IRQ();
469 
470 	pr_info("%s", arc_cpu_mumbojumbo(cpu_id, str, sizeof(str)));
471 
472 	arc_mmu_init();
473 	arc_cache_init();
474 
475 	pr_info("%s", arc_extn_mumbojumbo(cpu_id, str, sizeof(str)));
476 	pr_info("%s", arc_platform_smp_cpuinfo());
477 
478 	arc_chk_core_config();
479 }
480 
481 static inline bool uboot_arg_invalid(unsigned long addr)
482 {
483 	/*
484 	 * Check that it is a untranslated address (although MMU is not enabled
485 	 * yet, it being a high address ensures this is not by fluke)
486 	 */
487 	if (addr < PAGE_OFFSET)
488 		return true;
489 
490 	/* Check that address doesn't clobber resident kernel image */
491 	return addr >= (unsigned long)_stext && addr <= (unsigned long)_end;
492 }
493 
494 #define IGNORE_ARGS		"Ignore U-boot args: "
495 
496 /* uboot_tag values for U-boot - kernel ABI revision 0; see head.S */
497 #define UBOOT_TAG_NONE		0
498 #define UBOOT_TAG_CMDLINE	1
499 #define UBOOT_TAG_DTB		2
500 /* We always pass 0 as magic from U-boot */
501 #define UBOOT_MAGIC_VALUE	0
502 
503 void __init handle_uboot_args(void)
504 {
505 	bool use_embedded_dtb = true;
506 	bool append_cmdline = false;
507 
508 	/* check that we know this tag */
509 	if (uboot_tag != UBOOT_TAG_NONE &&
510 	    uboot_tag != UBOOT_TAG_CMDLINE &&
511 	    uboot_tag != UBOOT_TAG_DTB) {
512 		pr_warn(IGNORE_ARGS "invalid uboot tag: '%08x'\n", uboot_tag);
513 		goto ignore_uboot_args;
514 	}
515 
516 	if (uboot_magic != UBOOT_MAGIC_VALUE) {
517 		pr_warn(IGNORE_ARGS "non zero uboot magic\n");
518 		goto ignore_uboot_args;
519 	}
520 
521 	if (uboot_tag != UBOOT_TAG_NONE &&
522             uboot_arg_invalid((unsigned long)uboot_arg)) {
523 		pr_warn(IGNORE_ARGS "invalid uboot arg: '%px'\n", uboot_arg);
524 		goto ignore_uboot_args;
525 	}
526 
527 	/* see if U-boot passed an external Device Tree blob */
528 	if (uboot_tag == UBOOT_TAG_DTB) {
529 		machine_desc = setup_machine_fdt((void *)uboot_arg);
530 
531 		/* external Device Tree blob is invalid - use embedded one */
532 		use_embedded_dtb = !machine_desc;
533 	}
534 
535 	if (uboot_tag == UBOOT_TAG_CMDLINE)
536 		append_cmdline = true;
537 
538 ignore_uboot_args:
539 
540 	if (use_embedded_dtb) {
541 		machine_desc = setup_machine_fdt(__dtb_start);
542 		if (!machine_desc)
543 			panic("Embedded DT invalid\n");
544 	}
545 
546 	/*
547 	 * NOTE: @boot_command_line is populated by setup_machine_fdt() so this
548 	 * append processing can only happen after.
549 	 */
550 	if (append_cmdline) {
551 		/* Ensure a whitespace between the 2 cmdlines */
552 		strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
553 		strlcat(boot_command_line, uboot_arg, COMMAND_LINE_SIZE);
554 	}
555 }
556 
557 void __init setup_arch(char **cmdline_p)
558 {
559 	handle_uboot_args();
560 
561 	/* Save unparsed command line copy for /proc/cmdline */
562 	*cmdline_p = boot_command_line;
563 
564 	/* To force early parsing of things like mem=xxx */
565 	parse_early_param();
566 
567 	/* Platform/board specific: e.g. early console registration */
568 	if (machine_desc->init_early)
569 		machine_desc->init_early();
570 
571 	smp_init_cpus();
572 
573 	setup_processor();
574 	setup_arch_memory();
575 
576 	/* copy flat DT out of .init and then unflatten it */
577 	unflatten_and_copy_device_tree();
578 
579 	/* Can be issue if someone passes cmd line arg "ro"
580 	 * But that is unlikely so keeping it as it is
581 	 */
582 	root_mountflags &= ~MS_RDONLY;
583 
584 	arc_unwind_init();
585 }
586 
587 /*
588  * Called from start_kernel() - boot CPU only
589  */
590 void __init time_init(void)
591 {
592 	of_clk_init(NULL);
593 	timer_probe();
594 }
595 
596 static int __init customize_machine(void)
597 {
598 	if (machine_desc->init_machine)
599 		machine_desc->init_machine();
600 
601 	return 0;
602 }
603 arch_initcall(customize_machine);
604 
605 static int __init init_late_machine(void)
606 {
607 	if (machine_desc->init_late)
608 		machine_desc->init_late();
609 
610 	return 0;
611 }
612 late_initcall(init_late_machine);
613 /*
614  *  Get CPU information for use by the procfs.
615  */
616 
617 #define cpu_to_ptr(c)	((void *)(0xFFFF0000 | (unsigned int)(c)))
618 #define ptr_to_cpu(p)	(~0xFFFF0000UL & (unsigned int)(p))
619 
620 static int show_cpuinfo(struct seq_file *m, void *v)
621 {
622 	char *str;
623 	int cpu_id = ptr_to_cpu(v);
624 	struct device *cpu_dev = get_cpu_device(cpu_id);
625 	struct clk *cpu_clk;
626 	unsigned long freq = 0;
627 
628 	if (!cpu_online(cpu_id)) {
629 		seq_printf(m, "processor [%d]\t: Offline\n", cpu_id);
630 		goto done;
631 	}
632 
633 	str = (char *)__get_free_page(GFP_KERNEL);
634 	if (!str)
635 		goto done;
636 
637 	seq_printf(m, arc_cpu_mumbojumbo(cpu_id, str, PAGE_SIZE));
638 
639 	cpu_clk = clk_get(cpu_dev, NULL);
640 	if (IS_ERR(cpu_clk)) {
641 		seq_printf(m, "CPU speed \t: Cannot get clock for processor [%d]\n",
642 			   cpu_id);
643 	} else {
644 		freq = clk_get_rate(cpu_clk);
645 	}
646 	if (freq)
647 		seq_printf(m, "CPU speed\t: %lu.%02lu Mhz\n",
648 			   freq / 1000000, (freq / 10000) % 100);
649 
650 	seq_printf(m, "Bogo MIPS\t: %lu.%02lu\n",
651 		   loops_per_jiffy / (500000 / HZ),
652 		   (loops_per_jiffy / (5000 / HZ)) % 100);
653 
654 	seq_printf(m, arc_mmu_mumbojumbo(cpu_id, str, PAGE_SIZE));
655 	seq_printf(m, arc_cache_mumbojumbo(cpu_id, str, PAGE_SIZE));
656 	seq_printf(m, arc_extn_mumbojumbo(cpu_id, str, PAGE_SIZE));
657 	seq_printf(m, arc_platform_smp_cpuinfo());
658 
659 	free_page((unsigned long)str);
660 done:
661 	seq_printf(m, "\n");
662 
663 	return 0;
664 }
665 
666 static void *c_start(struct seq_file *m, loff_t *pos)
667 {
668 	/*
669 	 * Callback returns cpu-id to iterator for show routine, NULL to stop.
670 	 * However since NULL is also a valid cpu-id (0), we use a round-about
671 	 * way to pass it w/o having to kmalloc/free a 2 byte string.
672 	 * Encode cpu-id as 0xFFcccc, which is decoded by show routine.
673 	 */
674 	return *pos < nr_cpu_ids ? cpu_to_ptr(*pos) : NULL;
675 }
676 
677 static void *c_next(struct seq_file *m, void *v, loff_t *pos)
678 {
679 	++*pos;
680 	return c_start(m, pos);
681 }
682 
683 static void c_stop(struct seq_file *m, void *v)
684 {
685 }
686 
687 const struct seq_operations cpuinfo_op = {
688 	.start	= c_start,
689 	.next	= c_next,
690 	.stop	= c_stop,
691 	.show	= show_cpuinfo
692 };
693 
694 static DEFINE_PER_CPU(struct cpu, cpu_topology);
695 
696 static int __init topology_init(void)
697 {
698 	int cpu;
699 
700 	for_each_present_cpu(cpu)
701 	    register_cpu(&per_cpu(cpu_topology, cpu), cpu);
702 
703 	return 0;
704 }
705 
706 subsys_initcall(topology_init);
707