xref: /openbmc/linux/arch/arc/kernel/setup.c (revision e6e8c82b)
1 /*
2  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  */
8 
9 #include <linux/seq_file.h>
10 #include <linux/fs.h>
11 #include <linux/delay.h>
12 #include <linux/root_dev.h>
13 #include <linux/clk.h>
14 #include <linux/clk-provider.h>
15 #include <linux/clocksource.h>
16 #include <linux/console.h>
17 #include <linux/module.h>
18 #include <linux/cpu.h>
19 #include <linux/of_fdt.h>
20 #include <linux/of.h>
21 #include <linux/cache.h>
22 #include <uapi/linux/mount.h>
23 #include <asm/sections.h>
24 #include <asm/arcregs.h>
25 #include <asm/tlb.h>
26 #include <asm/setup.h>
27 #include <asm/page.h>
28 #include <asm/irq.h>
29 #include <asm/unwind.h>
30 #include <asm/mach_desc.h>
31 #include <asm/smp.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 char __initdata *uboot_arg;
40 
41 const struct machine_desc *machine_desc;
42 
43 struct task_struct *_current_task[NR_CPUS];	/* For stack switching */
44 
45 struct cpuinfo_arc cpuinfo_arc700[NR_CPUS];
46 
47 static const struct id_to_str arc_cpu_rel[] = {
48 #ifdef CONFIG_ISA_ARCOMPACT
49 	{ 0x34, "R4.10"},
50 	{ 0x35, "R4.11"},
51 #else
52 	{ 0x51, "R2.0" },
53 	{ 0x52, "R2.1" },
54 	{ 0x53, "R3.0" },
55 	{ 0x54, "R3.10a" },
56 #endif
57 	{ 0x00, NULL   }
58 };
59 
60 static const struct id_to_str arc_cpu_nm[] = {
61 #ifdef CONFIG_ISA_ARCOMPACT
62 	{ 0x20, "ARC 600"   },
63 	{ 0x30, "ARC 770"   },  /* 750 identified seperately */
64 #else
65 	{ 0x40, "ARC EM"  },
66 	{ 0x50, "ARC HS38"  },
67 	{ 0x54, "ARC HS48"  },
68 #endif
69 	{ 0x00, "Unknown"   }
70 };
71 
72 static void read_decode_ccm_bcr(struct cpuinfo_arc *cpu)
73 {
74 	if (is_isa_arcompact()) {
75 		struct bcr_iccm_arcompact iccm;
76 		struct bcr_dccm_arcompact dccm;
77 
78 		READ_BCR(ARC_REG_ICCM_BUILD, iccm);
79 		if (iccm.ver) {
80 			cpu->iccm.sz = 4096 << iccm.sz;	/* 8K to 512K */
81 			cpu->iccm.base_addr = iccm.base << 16;
82 		}
83 
84 		READ_BCR(ARC_REG_DCCM_BUILD, dccm);
85 		if (dccm.ver) {
86 			unsigned long base;
87 			cpu->dccm.sz = 2048 << dccm.sz;	/* 2K to 256K */
88 
89 			base = read_aux_reg(ARC_REG_DCCM_BASE_BUILD);
90 			cpu->dccm.base_addr = base & ~0xF;
91 		}
92 	} else {
93 		struct bcr_iccm_arcv2 iccm;
94 		struct bcr_dccm_arcv2 dccm;
95 		unsigned long region;
96 
97 		READ_BCR(ARC_REG_ICCM_BUILD, iccm);
98 		if (iccm.ver) {
99 			cpu->iccm.sz = 256 << iccm.sz00;	/* 512B to 16M */
100 			if (iccm.sz00 == 0xF && iccm.sz01 > 0)
101 				cpu->iccm.sz <<= iccm.sz01;
102 
103 			region = read_aux_reg(ARC_REG_AUX_ICCM);
104 			cpu->iccm.base_addr = region & 0xF0000000;
105 		}
106 
107 		READ_BCR(ARC_REG_DCCM_BUILD, dccm);
108 		if (dccm.ver) {
109 			cpu->dccm.sz = 256 << dccm.sz0;
110 			if (dccm.sz0 == 0xF && dccm.sz1 > 0)
111 				cpu->dccm.sz <<= dccm.sz1;
112 
113 			region = read_aux_reg(ARC_REG_AUX_DCCM);
114 			cpu->dccm.base_addr = region & 0xF0000000;
115 		}
116 	}
117 }
118 
119 static void read_arc_build_cfg_regs(void)
120 {
121 	struct bcr_timer timer;
122 	struct bcr_generic bcr;
123 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()];
124 	const struct id_to_str *tbl;
125 	struct bcr_isa_arcv2 isa;
126 
127 	FIX_PTR(cpu);
128 
129 	READ_BCR(AUX_IDENTITY, cpu->core);
130 
131 	for (tbl = &arc_cpu_rel[0]; tbl->id != 0; tbl++) {
132 		if (cpu->core.family == tbl->id) {
133 			cpu->details = tbl->str;
134 			break;
135 		}
136 	}
137 
138 	for (tbl = &arc_cpu_nm[0]; tbl->id != 0; tbl++) {
139 		if ((cpu->core.family & 0xF4) == tbl->id)
140 			break;
141 	}
142 	cpu->name = tbl->str;
143 
144 	READ_BCR(ARC_REG_TIMERS_BCR, timer);
145 	cpu->extn.timer0 = timer.t0;
146 	cpu->extn.timer1 = timer.t1;
147 	cpu->extn.rtc = timer.rtc;
148 
149 	cpu->vec_base = read_aux_reg(AUX_INTR_VEC_BASE);
150 
151 	READ_BCR(ARC_REG_MUL_BCR, cpu->extn_mpy);
152 
153 	cpu->extn.norm = read_aux_reg(ARC_REG_NORM_BCR) > 1 ? 1 : 0; /* 2,3 */
154 	cpu->extn.barrel = read_aux_reg(ARC_REG_BARREL_BCR) > 1 ? 1 : 0; /* 2,3 */
155 	cpu->extn.swap = read_aux_reg(ARC_REG_SWAP_BCR) ? 1 : 0;        /* 1,3 */
156 	cpu->extn.crc = read_aux_reg(ARC_REG_CRC_BCR) ? 1 : 0;
157 	cpu->extn.minmax = read_aux_reg(ARC_REG_MIXMAX_BCR) > 1 ? 1 : 0; /* 2 */
158 	cpu->extn.swape = (cpu->core.family >= 0x34) ? 1 :
159 				IS_ENABLED(CONFIG_ARC_HAS_SWAPE);
160 
161 	READ_BCR(ARC_REG_XY_MEM_BCR, cpu->extn_xymem);
162 
163 	/* Read CCM BCRs for boot reporting even if not enabled in Kconfig */
164 	read_decode_ccm_bcr(cpu);
165 
166 	read_decode_mmu_bcr();
167 	read_decode_cache_bcr();
168 
169 	if (is_isa_arcompact()) {
170 		struct bcr_fp_arcompact sp, dp;
171 		struct bcr_bpu_arcompact bpu;
172 
173 		READ_BCR(ARC_REG_FP_BCR, sp);
174 		READ_BCR(ARC_REG_DPFP_BCR, dp);
175 		cpu->extn.fpu_sp = sp.ver ? 1 : 0;
176 		cpu->extn.fpu_dp = dp.ver ? 1 : 0;
177 
178 		READ_BCR(ARC_REG_BPU_BCR, bpu);
179 		cpu->bpu.ver = bpu.ver;
180 		cpu->bpu.full = bpu.fam ? 1 : 0;
181 		if (bpu.ent) {
182 			cpu->bpu.num_cache = 256 << (bpu.ent - 1);
183 			cpu->bpu.num_pred = 256 << (bpu.ent - 1);
184 		}
185 	} else {
186 		struct bcr_fp_arcv2 spdp;
187 		struct bcr_bpu_arcv2 bpu;
188 
189 		READ_BCR(ARC_REG_FP_V2_BCR, spdp);
190 		cpu->extn.fpu_sp = spdp.sp ? 1 : 0;
191 		cpu->extn.fpu_dp = spdp.dp ? 1 : 0;
192 
193 		READ_BCR(ARC_REG_BPU_BCR, bpu);
194 		cpu->bpu.ver = bpu.ver;
195 		cpu->bpu.full = bpu.ft;
196 		cpu->bpu.num_cache = 256 << bpu.bce;
197 		cpu->bpu.num_pred = 2048 << bpu.pte;
198 
199 		if (cpu->core.family >= 0x54) {
200 			unsigned int exec_ctrl;
201 
202 			READ_BCR(AUX_EXEC_CTRL, exec_ctrl);
203 			cpu->extn.dual_enb = !(exec_ctrl & 1);
204 
205 			/* dual issue always present for this core */
206 			cpu->extn.dual = 1;
207 		}
208 	}
209 
210 	READ_BCR(ARC_REG_AP_BCR, bcr);
211 	cpu->extn.ap = bcr.ver ? 1 : 0;
212 
213 	READ_BCR(ARC_REG_SMART_BCR, bcr);
214 	cpu->extn.smart = bcr.ver ? 1 : 0;
215 
216 	READ_BCR(ARC_REG_RTT_BCR, bcr);
217 	cpu->extn.rtt = bcr.ver ? 1 : 0;
218 
219 	cpu->extn.debug = cpu->extn.ap | cpu->extn.smart | cpu->extn.rtt;
220 
221 	READ_BCR(ARC_REG_ISA_CFG_BCR, isa);
222 
223 	/* some hacks for lack of feature BCR info in old ARC700 cores */
224 	if (is_isa_arcompact()) {
225 		if (!isa.ver)	/* ISA BCR absent, use Kconfig info */
226 			cpu->isa.atomic = IS_ENABLED(CONFIG_ARC_HAS_LLSC);
227 		else {
228 			/* ARC700_BUILD only has 2 bits of isa info */
229 			struct bcr_generic bcr = *(struct bcr_generic *)&isa;
230 			cpu->isa.atomic = bcr.info & 1;
231 		}
232 
233 		cpu->isa.be = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
234 
235 		 /* there's no direct way to distinguish 750 vs. 770 */
236 		if (unlikely(cpu->core.family < 0x34 || cpu->mmu.ver < 3))
237 			cpu->name = "ARC750";
238 	} else {
239 		cpu->isa = isa;
240 	}
241 }
242 
243 static char *arc_cpu_mumbojumbo(int cpu_id, char *buf, int len)
244 {
245 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[cpu_id];
246 	struct bcr_identity *core = &cpu->core;
247 	int i, n = 0, ua = 0;
248 
249 	FIX_PTR(cpu);
250 
251 	n += scnprintf(buf + n, len - n,
252 		       "\nIDENTITY\t: ARCVER [%#02x] ARCNUM [%#02x] CHIPID [%#4x]\n",
253 		       core->family, core->cpu_id, core->chip_id);
254 
255 	n += scnprintf(buf + n, len - n, "processor [%d]\t: %s %s (%s ISA) %s%s%s\n",
256 		       cpu_id, cpu->name, cpu->details,
257 		       is_isa_arcompact() ? "ARCompact" : "ARCv2",
258 		       IS_AVAIL1(cpu->isa.be, "[Big-Endian]"),
259 		       IS_AVAIL3(cpu->extn.dual, cpu->extn.dual_enb, " Dual-Issue "));
260 
261 	n += scnprintf(buf + n, len - n, "Timers\t\t: %s%s%s%s%s%s\nISA Extn\t: ",
262 		       IS_AVAIL1(cpu->extn.timer0, "Timer0 "),
263 		       IS_AVAIL1(cpu->extn.timer1, "Timer1 "),
264 		       IS_AVAIL2(cpu->extn.rtc, "RTC [UP 64-bit] ", CONFIG_ARC_TIMERS_64BIT),
265 		       IS_AVAIL2(cpu->extn.gfrc, "GFRC [SMP 64-bit] ", CONFIG_ARC_TIMERS_64BIT));
266 
267 #ifdef __ARC_UNALIGNED__
268 	ua = 1;
269 #endif
270 	n += i = scnprintf(buf + n, len - n, "%s%s%s%s%s%s",
271 			   IS_AVAIL2(cpu->isa.atomic, "atomic ", CONFIG_ARC_HAS_LLSC),
272 			   IS_AVAIL2(cpu->isa.ldd, "ll64 ", CONFIG_ARC_HAS_LL64),
273 			   IS_AVAIL1(cpu->isa.unalign, "unalign "), IS_USED_RUN(ua));
274 
275 	if (i)
276 		n += scnprintf(buf + n, len - n, "\n\t\t: ");
277 
278 	if (cpu->extn_mpy.ver) {
279 		if (cpu->extn_mpy.ver <= 0x2) {	/* ARCompact */
280 			n += scnprintf(buf + n, len - n, "mpy ");
281 		} else {
282 			int opt = 2;	/* stock MPY/MPYH */
283 
284 			if (cpu->extn_mpy.dsp)	/* OPT 7-9 */
285 				opt = cpu->extn_mpy.dsp + 6;
286 
287 			n += scnprintf(buf + n, len - n, "mpy[opt %d] ", opt);
288 		}
289 	}
290 
291 	n += scnprintf(buf + n, len - n, "%s%s%s%s%s%s%s%s\n",
292 		       IS_AVAIL1(cpu->isa.div_rem, "div_rem "),
293 		       IS_AVAIL1(cpu->extn.norm, "norm "),
294 		       IS_AVAIL1(cpu->extn.barrel, "barrel-shift "),
295 		       IS_AVAIL1(cpu->extn.swap, "swap "),
296 		       IS_AVAIL1(cpu->extn.minmax, "minmax "),
297 		       IS_AVAIL1(cpu->extn.crc, "crc "),
298 		       IS_AVAIL2(cpu->extn.swape, "swape", CONFIG_ARC_HAS_SWAPE));
299 
300 	if (cpu->bpu.ver)
301 		n += scnprintf(buf + n, len - n,
302 			      "BPU\t\t: %s%s match, cache:%d, Predict Table:%d",
303 			      IS_AVAIL1(cpu->bpu.full, "full"),
304 			      IS_AVAIL1(!cpu->bpu.full, "partial"),
305 			      cpu->bpu.num_cache, cpu->bpu.num_pred);
306 
307 	if (is_isa_arcv2()) {
308 		struct bcr_lpb lpb;
309 
310 		READ_BCR(ARC_REG_LPB_BUILD, lpb);
311 		if (lpb.ver) {
312 			unsigned int ctl;
313 			ctl = read_aux_reg(ARC_REG_LPB_CTRL);
314 
315 			n += scnprintf(buf + n, len - n, " Loop Buffer:%d %s",
316 				lpb.entries,
317 				IS_DISABLED_RUN(!ctl));
318 		}
319 	}
320 
321 	n += scnprintf(buf + n, len - n, "\n");
322 	return buf;
323 }
324 
325 static char *arc_extn_mumbojumbo(int cpu_id, char *buf, int len)
326 {
327 	int n = 0;
328 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[cpu_id];
329 
330 	FIX_PTR(cpu);
331 
332 	n += scnprintf(buf + n, len - n, "Vector Table\t: %#x\n", cpu->vec_base);
333 
334 	if (cpu->extn.fpu_sp || cpu->extn.fpu_dp)
335 		n += scnprintf(buf + n, len - n, "FPU\t\t: %s%s\n",
336 			       IS_AVAIL1(cpu->extn.fpu_sp, "SP "),
337 			       IS_AVAIL1(cpu->extn.fpu_dp, "DP "));
338 
339 	if (cpu->extn.debug)
340 		n += scnprintf(buf + n, len - n, "DEBUG\t\t: %s%s%s\n",
341 			       IS_AVAIL1(cpu->extn.ap, "ActionPoint "),
342 			       IS_AVAIL1(cpu->extn.smart, "smaRT "),
343 			       IS_AVAIL1(cpu->extn.rtt, "RTT "));
344 
345 	if (cpu->dccm.sz || cpu->iccm.sz)
346 		n += scnprintf(buf + n, len - n, "Extn [CCM]\t: DCCM @ %x, %d KB / ICCM: @ %x, %d KB\n",
347 			       cpu->dccm.base_addr, TO_KB(cpu->dccm.sz),
348 			       cpu->iccm.base_addr, TO_KB(cpu->iccm.sz));
349 
350 	if (is_isa_arcv2()) {
351 
352 		/* Error Protection: ECC/Parity */
353 		struct bcr_erp erp;
354 		READ_BCR(ARC_REG_ERP_BUILD, erp);
355 
356 		if (erp.ver) {
357 			struct  ctl_erp ctl;
358 			READ_BCR(ARC_REG_ERP_CTRL, ctl);
359 
360 			/* inverted bits: 0 means enabled */
361 			n += scnprintf(buf + n, len - n, "Extn [ECC]\t: %s%s%s%s%s%s\n",
362 				IS_AVAIL3(erp.ic,  !ctl.dpi, "IC "),
363 				IS_AVAIL3(erp.dc,  !ctl.dpd, "DC "),
364 				IS_AVAIL3(erp.mmu, !ctl.mpd, "MMU "));
365 		}
366 	}
367 
368 	n += scnprintf(buf + n, len - n, "OS ABI [v%d]\t: %s\n",
369 			EF_ARC_OSABI_CURRENT >> 8,
370 			EF_ARC_OSABI_CURRENT == EF_ARC_OSABI_V3 ?
371 			"no-legacy-syscalls" : "64-bit data any register aligned");
372 
373 	return buf;
374 }
375 
376 static void arc_chk_core_config(void)
377 {
378 	struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()];
379 	int saved = 0, present = 0;
380 	char *opt_nm = NULL;
381 
382 	if (!cpu->extn.timer0)
383 		panic("Timer0 is not present!\n");
384 
385 	if (!cpu->extn.timer1)
386 		panic("Timer1 is not present!\n");
387 
388 #ifdef CONFIG_ARC_HAS_DCCM
389 	/*
390 	 * DCCM can be arbit placed in hardware.
391 	 * Make sure it's placement/sz matches what Linux is built with
392 	 */
393 	if ((unsigned int)__arc_dccm_base != cpu->dccm.base_addr)
394 		panic("Linux built with incorrect DCCM Base address\n");
395 
396 	if (CONFIG_ARC_DCCM_SZ != cpu->dccm.sz)
397 		panic("Linux built with incorrect DCCM Size\n");
398 #endif
399 
400 #ifdef CONFIG_ARC_HAS_ICCM
401 	if (CONFIG_ARC_ICCM_SZ != cpu->iccm.sz)
402 		panic("Linux built with incorrect ICCM Size\n");
403 #endif
404 
405 	/*
406 	 * FP hardware/software config sanity
407 	 * -If hardware present, kernel needs to save/restore FPU state
408 	 * -If not, it will crash trying to save/restore the non-existant regs
409 	 */
410 
411 	if (is_isa_arcompact()) {
412 		opt_nm = "CONFIG_ARC_FPU_SAVE_RESTORE";
413 		saved = IS_ENABLED(CONFIG_ARC_FPU_SAVE_RESTORE);
414 
415 		/* only DPDP checked since SP has no arch visible regs */
416 		present = cpu->extn.fpu_dp;
417 	} else {
418 		opt_nm = "CONFIG_ARC_HAS_ACCL_REGS";
419 		saved = IS_ENABLED(CONFIG_ARC_HAS_ACCL_REGS);
420 
421 		/* Accumulator Low:High pair (r58:59) present if DSP MPY or FPU */
422 		present = cpu->extn_mpy.dsp | cpu->extn.fpu_sp | cpu->extn.fpu_dp;
423 	}
424 
425 	if (present && !saved)
426 		pr_warn("Enable %s for working apps\n", opt_nm);
427 	else if (!present && saved)
428 		panic("Disable %s, hardware NOT present\n", opt_nm);
429 }
430 
431 /*
432  * Initialize and setup the processor core
433  * This is called by all the CPUs thus should not do special case stuff
434  *    such as only for boot CPU etc
435  */
436 
437 void setup_processor(void)
438 {
439 	char str[512];
440 	int cpu_id = smp_processor_id();
441 
442 	read_arc_build_cfg_regs();
443 	arc_init_IRQ();
444 
445 	pr_info("%s", arc_cpu_mumbojumbo(cpu_id, str, sizeof(str)));
446 
447 	arc_mmu_init();
448 	arc_cache_init();
449 
450 	pr_info("%s", arc_extn_mumbojumbo(cpu_id, str, sizeof(str)));
451 	pr_info("%s", arc_platform_smp_cpuinfo());
452 
453 	arc_chk_core_config();
454 }
455 
456 static inline int is_kernel(unsigned long addr)
457 {
458 	if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
459 		return 1;
460 	return 0;
461 }
462 
463 void __init setup_arch(char **cmdline_p)
464 {
465 #ifdef CONFIG_ARC_UBOOT_SUPPORT
466 	/* make sure that uboot passed pointer to cmdline/dtb is valid */
467 	if (uboot_tag && is_kernel((unsigned long)uboot_arg))
468 		panic("Invalid uboot arg\n");
469 
470 	/* See if u-boot passed an external Device Tree blob */
471 	machine_desc = setup_machine_fdt(uboot_arg);	/* uboot_tag == 2 */
472 	if (!machine_desc)
473 #endif
474 	{
475 		/* No, so try the embedded one */
476 		machine_desc = setup_machine_fdt(__dtb_start);
477 		if (!machine_desc)
478 			panic("Embedded DT invalid\n");
479 
480 		/*
481 		 * If we are here, it is established that @uboot_arg didn't
482 		 * point to DT blob. Instead if u-boot says it is cmdline,
483 		 * append to embedded DT cmdline.
484 		 * setup_machine_fdt() would have populated @boot_command_line
485 		 */
486 		if (uboot_tag == 1) {
487 			/* Ensure a whitespace between the 2 cmdlines */
488 			strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
489 			strlcat(boot_command_line, uboot_arg,
490 				COMMAND_LINE_SIZE);
491 		}
492 	}
493 
494 	/* Save unparsed command line copy for /proc/cmdline */
495 	*cmdline_p = boot_command_line;
496 
497 	/* To force early parsing of things like mem=xxx */
498 	parse_early_param();
499 
500 	/* Platform/board specific: e.g. early console registration */
501 	if (machine_desc->init_early)
502 		machine_desc->init_early();
503 
504 	smp_init_cpus();
505 
506 	setup_processor();
507 	setup_arch_memory();
508 
509 	/* copy flat DT out of .init and then unflatten it */
510 	unflatten_and_copy_device_tree();
511 
512 	/* Can be issue if someone passes cmd line arg "ro"
513 	 * But that is unlikely so keeping it as it is
514 	 */
515 	root_mountflags &= ~MS_RDONLY;
516 
517 #if defined(CONFIG_VT) && defined(CONFIG_DUMMY_CONSOLE)
518 	conswitchp = &dummy_con;
519 #endif
520 
521 	arc_unwind_init();
522 }
523 
524 /*
525  * Called from start_kernel() - boot CPU only
526  */
527 void __init time_init(void)
528 {
529 	of_clk_init(NULL);
530 	timer_probe();
531 }
532 
533 static int __init customize_machine(void)
534 {
535 	if (machine_desc->init_machine)
536 		machine_desc->init_machine();
537 
538 	return 0;
539 }
540 arch_initcall(customize_machine);
541 
542 static int __init init_late_machine(void)
543 {
544 	if (machine_desc->init_late)
545 		machine_desc->init_late();
546 
547 	return 0;
548 }
549 late_initcall(init_late_machine);
550 /*
551  *  Get CPU information for use by the procfs.
552  */
553 
554 #define cpu_to_ptr(c)	((void *)(0xFFFF0000 | (unsigned int)(c)))
555 #define ptr_to_cpu(p)	(~0xFFFF0000UL & (unsigned int)(p))
556 
557 static int show_cpuinfo(struct seq_file *m, void *v)
558 {
559 	char *str;
560 	int cpu_id = ptr_to_cpu(v);
561 	struct device *cpu_dev = get_cpu_device(cpu_id);
562 	struct clk *cpu_clk;
563 	unsigned long freq = 0;
564 
565 	if (!cpu_online(cpu_id)) {
566 		seq_printf(m, "processor [%d]\t: Offline\n", cpu_id);
567 		goto done;
568 	}
569 
570 	str = (char *)__get_free_page(GFP_KERNEL);
571 	if (!str)
572 		goto done;
573 
574 	seq_printf(m, arc_cpu_mumbojumbo(cpu_id, str, PAGE_SIZE));
575 
576 	cpu_clk = clk_get(cpu_dev, NULL);
577 	if (IS_ERR(cpu_clk)) {
578 		seq_printf(m, "CPU speed \t: Cannot get clock for processor [%d]\n",
579 			   cpu_id);
580 	} else {
581 		freq = clk_get_rate(cpu_clk);
582 	}
583 	if (freq)
584 		seq_printf(m, "CPU speed\t: %lu.%02lu Mhz\n",
585 			   freq / 1000000, (freq / 10000) % 100);
586 
587 	seq_printf(m, "Bogo MIPS\t: %lu.%02lu\n",
588 		   loops_per_jiffy / (500000 / HZ),
589 		   (loops_per_jiffy / (5000 / HZ)) % 100);
590 
591 	seq_printf(m, arc_mmu_mumbojumbo(cpu_id, str, PAGE_SIZE));
592 	seq_printf(m, arc_cache_mumbojumbo(cpu_id, str, PAGE_SIZE));
593 	seq_printf(m, arc_extn_mumbojumbo(cpu_id, str, PAGE_SIZE));
594 	seq_printf(m, arc_platform_smp_cpuinfo());
595 
596 	free_page((unsigned long)str);
597 done:
598 	seq_printf(m, "\n");
599 
600 	return 0;
601 }
602 
603 static void *c_start(struct seq_file *m, loff_t *pos)
604 {
605 	/*
606 	 * Callback returns cpu-id to iterator for show routine, NULL to stop.
607 	 * However since NULL is also a valid cpu-id (0), we use a round-about
608 	 * way to pass it w/o having to kmalloc/free a 2 byte string.
609 	 * Encode cpu-id as 0xFFcccc, which is decoded by show routine.
610 	 */
611 	return *pos < nr_cpu_ids ? cpu_to_ptr(*pos) : NULL;
612 }
613 
614 static void *c_next(struct seq_file *m, void *v, loff_t *pos)
615 {
616 	++*pos;
617 	return c_start(m, pos);
618 }
619 
620 static void c_stop(struct seq_file *m, void *v)
621 {
622 }
623 
624 const struct seq_operations cpuinfo_op = {
625 	.start	= c_start,
626 	.next	= c_next,
627 	.stop	= c_stop,
628 	.show	= show_cpuinfo
629 };
630 
631 static DEFINE_PER_CPU(struct cpu, cpu_topology);
632 
633 static int __init topology_init(void)
634 {
635 	int cpu;
636 
637 	for_each_present_cpu(cpu)
638 	    register_cpu(&per_cpu(cpu_topology, cpu), cpu);
639 
640 	return 0;
641 }
642 
643 subsys_initcall(topology_init);
644