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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#include <soc/arc/mcip.h>
33
34#define FIX_PTR(x) __asm__ __volatile__(";" : "+r"(x))
35
36unsigned int intr_to_DE_cnt;
37
38/* Part of U-boot ABI: see head.S */
39int __initdata uboot_tag;
40int __initdata uboot_magic;
41char __initdata *uboot_arg;
42
43const struct machine_desc *machine_desc;
44
45struct task_struct *_current_task[NR_CPUS]; /* For stack switching */
46
47struct cpuinfo_arc {
48 int arcver;
49 unsigned int t0:1, t1:1;
50 struct {
51 unsigned long base;
52 unsigned int sz;
53 } iccm, dccm;
54};
55
56#ifdef CONFIG_ISA_ARCV2
57
58static const struct id_to_str arc_hs_rel[] = {
59 /* ID.ARCVER, Release */
60 { 0x51, "R2.0" },
61 { 0x52, "R2.1" },
62 { 0x53, "R3.0" },
63};
64
65static const struct id_to_str arc_hs_ver54_rel[] = {
66 /* UARCH.MAJOR, Release */
67 { 0, "R3.10a"},
68 { 1, "R3.50a"},
69 { 2, "R3.60a"},
70 { 3, "R4.00a"},
71 { 0xFF, NULL }
72};
73#endif
74
75static int
76arcompact_mumbojumbo(int c, struct cpuinfo_arc *info, char *buf, int len)
77{
78 int n = 0;
79#ifdef CONFIG_ISA_ARCOMPACT
80 char *cpu_nm, *isa_nm = "ARCompact";
81 struct bcr_fp_arcompact fpu_sp, fpu_dp;
82 int atomic = 0, be, present;
83 int bpu_full, bpu_cache, bpu_pred;
84 struct bcr_bpu_arcompact bpu;
85 struct bcr_iccm_arcompact iccm;
86 struct bcr_dccm_arcompact dccm;
87 struct bcr_generic isa;
88
89 READ_BCR(ARC_REG_ISA_CFG_BCR, isa);
90
91 if (!isa.ver) /* ISA BCR absent, use Kconfig info */
92 atomic = IS_ENABLED(CONFIG_ARC_HAS_LLSC);
93 else {
94 /* ARC700_BUILD only has 2 bits of isa info */
95 atomic = isa.info & 1;
96 }
97
98 be = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
99
100 if (info->arcver < 0x34)
101 cpu_nm = "ARC750";
102 else
103 cpu_nm = "ARC770";
104
105 n += scnprintf(buf + n, len - n, "processor [%d]\t: %s (%s ISA) %s%s%s\n",
106 c, cpu_nm, isa_nm,
107 IS_AVAIL2(atomic, "atomic ", CONFIG_ARC_HAS_LLSC),
108 IS_AVAIL1(be, "[Big-Endian]"));
109
110 READ_BCR(ARC_REG_FP_BCR, fpu_sp);
111 READ_BCR(ARC_REG_DPFP_BCR, fpu_dp);
112
113 if (fpu_sp.ver | fpu_dp.ver)
114 n += scnprintf(buf + n, len - n, "FPU\t\t: %s%s\n",
115 IS_AVAIL1(fpu_sp.ver, "SP "),
116 IS_AVAIL1(fpu_dp.ver, "DP "));
117
118 READ_BCR(ARC_REG_BPU_BCR, bpu);
119 bpu_full = bpu.fam ? 1 : 0;
120 bpu_cache = 256 << (bpu.ent - 1);
121 bpu_pred = 256 << (bpu.ent - 1);
122
123 n += scnprintf(buf + n, len - n,
124 "BPU\t\t: %s%s match, cache:%d, Predict Table:%d\n",
125 IS_AVAIL1(bpu_full, "full"),
126 IS_AVAIL1(!bpu_full, "partial"),
127 bpu_cache, bpu_pred);
128
129 READ_BCR(ARC_REG_ICCM_BUILD, iccm);
130 if (iccm.ver) {
131 info->iccm.sz = 4096 << iccm.sz; /* 8K to 512K */
132 info->iccm.base = iccm.base << 16;
133 }
134
135 READ_BCR(ARC_REG_DCCM_BUILD, dccm);
136 if (dccm.ver) {
137 unsigned long base;
138 info->dccm.sz = 2048 << dccm.sz; /* 2K to 256K */
139
140 base = read_aux_reg(ARC_REG_DCCM_BASE_BUILD);
141 info->dccm.base = base & ~0xF;
142 }
143
144 /* ARCompact ISA specific sanity checks */
145 present = fpu_dp.ver; /* SP has no arch visible regs */
146 CHK_OPT_STRICT(CONFIG_ARC_FPU_SAVE_RESTORE, present);
147#endif
148 return n;
149
150}
151
152static int arcv2_mumbojumbo(int c, struct cpuinfo_arc *info, char *buf, int len)
153{
154 int n = 0;
155#ifdef CONFIG_ISA_ARCV2
156 const char *release = "", *cpu_nm = "HS38", *isa_nm = "ARCv2";
157 int dual_issue = 0, dual_enb = 0, mpy_opt, present;
158 int bpu_full, bpu_cache, bpu_pred, bpu_ret_stk;
159 char mpy_nm[16], lpb_nm[32];
160 struct bcr_isa_arcv2 isa;
161 struct bcr_mpy mpy;
162 struct bcr_fp_arcv2 fpu;
163 struct bcr_bpu_arcv2 bpu;
164 struct bcr_lpb lpb;
165 struct bcr_iccm_arcv2 iccm;
166 struct bcr_dccm_arcv2 dccm;
167 struct bcr_erp erp;
168
169 /*
170 * Initial HS cores bumped AUX IDENTITY.ARCVER for each release until
171 * ARCVER 0x54 which introduced AUX MICRO_ARCH_BUILD and subsequent
172 * releases only update it.
173 */
174
175 if (info->arcver > 0x50 && info->arcver <= 0x53) {
176 release = arc_hs_rel[info->arcver - 0x51].str;
177 } else {
178 const struct id_to_str *tbl;
179 struct bcr_uarch_build uarch;
180
181 READ_BCR(ARC_REG_MICRO_ARCH_BCR, uarch);
182
183 for (tbl = &arc_hs_ver54_rel[0]; tbl->id != 0xFF; tbl++) {
184 if (uarch.maj == tbl->id) {
185 release = tbl->str;
186 break;
187 }
188 }
189 if (uarch.prod == 4) {
190 unsigned int exec_ctrl;
191
192 cpu_nm = "HS48";
193 dual_issue = 1;
194 /* if dual issue hardware, is it enabled ? */
195 READ_BCR(AUX_EXEC_CTRL, exec_ctrl);
196 dual_enb = !(exec_ctrl & 1);
197 }
198 }
199
200 READ_BCR(ARC_REG_ISA_CFG_BCR, isa);
201
202 n += scnprintf(buf + n, len - n, "processor [%d]\t: %s %s (%s ISA) %s%s%s\n",
203 c, cpu_nm, release, isa_nm,
204 IS_AVAIL1(isa.be, "[Big-Endian]"),
205 IS_AVAIL3(dual_issue, dual_enb, " Dual-Issue "));
206
207 READ_BCR(ARC_REG_MPY_BCR, mpy);
208 mpy_opt = 2; /* stock MPY/MPYH */
209 if (mpy.dsp) /* OPT 7-9 */
210 mpy_opt = mpy.dsp + 6;
211
212 scnprintf(mpy_nm, 16, "mpy[opt %d] ", mpy_opt);
213
214 READ_BCR(ARC_REG_FP_V2_BCR, fpu);
215
216 n += scnprintf(buf + n, len - n, "ISA Extn\t: %s%s%s%s%s%s%s%s%s%s%s\n",
217 IS_AVAIL2(isa.atomic, "atomic ", CONFIG_ARC_HAS_LLSC),
218 IS_AVAIL2(isa.ldd, "ll64 ", CONFIG_ARC_HAS_LL64),
219 IS_AVAIL2(isa.unalign, "unalign ", CONFIG_ARC_USE_UNALIGNED_MEM_ACCESS),
220 IS_AVAIL1(mpy.ver, mpy_nm),
221 IS_AVAIL1(isa.div_rem, "div_rem "),
222 IS_AVAIL1((fpu.sp | fpu.dp), " FPU:"),
223 IS_AVAIL1(fpu.sp, " sp"),
224 IS_AVAIL1(fpu.dp, " dp"));
225
226 READ_BCR(ARC_REG_BPU_BCR, bpu);
227 bpu_full = bpu.ft;
228 bpu_cache = 256 << bpu.bce;
229 bpu_pred = 2048 << bpu.pte;
230 bpu_ret_stk = 4 << bpu.rse;
231
232 READ_BCR(ARC_REG_LPB_BUILD, lpb);
233 if (lpb.ver) {
234 unsigned int ctl;
235 ctl = read_aux_reg(ARC_REG_LPB_CTRL);
236
237 scnprintf(lpb_nm, sizeof(lpb_nm), " Loop Buffer:%d %s",
238 lpb.entries, IS_DISABLED_RUN(!ctl));
239 }
240
241 n += scnprintf(buf + n, len - n,
242 "BPU\t\t: %s%s match, cache:%d, Predict Table:%d Return stk: %d%s\n",
243 IS_AVAIL1(bpu_full, "full"),
244 IS_AVAIL1(!bpu_full, "partial"),
245 bpu_cache, bpu_pred, bpu_ret_stk,
246 lpb_nm);
247
248 READ_BCR(ARC_REG_ICCM_BUILD, iccm);
249 if (iccm.ver) {
250 unsigned long base;
251 info->iccm.sz = 256 << iccm.sz00; /* 512B to 16M */
252 if (iccm.sz00 == 0xF && iccm.sz01 > 0)
253 info->iccm.sz <<= iccm.sz01;
254 base = read_aux_reg(ARC_REG_AUX_ICCM);
255 info->iccm.base = base & 0xF0000000;
256 }
257
258 READ_BCR(ARC_REG_DCCM_BUILD, dccm);
259 if (dccm.ver) {
260 unsigned long base;
261 info->dccm.sz = 256 << dccm.sz0;
262 if (dccm.sz0 == 0xF && dccm.sz1 > 0)
263 info->dccm.sz <<= dccm.sz1;
264 base = read_aux_reg(ARC_REG_AUX_DCCM);
265 info->dccm.base = base & 0xF0000000;
266 }
267
268 /* Error Protection: ECC/Parity */
269 READ_BCR(ARC_REG_ERP_BUILD, erp);
270 if (erp.ver) {
271 struct ctl_erp ctl;
272 READ_BCR(ARC_REG_ERP_CTRL, ctl);
273 /* inverted bits: 0 means enabled */
274 n += scnprintf(buf + n, len - n, "Extn [ECC]\t: %s%s%s%s%s%s\n",
275 IS_AVAIL3(erp.ic, !ctl.dpi, "IC "),
276 IS_AVAIL3(erp.dc, !ctl.dpd, "DC "),
277 IS_AVAIL3(erp.mmu, !ctl.mpd, "MMU "));
278 }
279
280 /* ARCv2 ISA specific sanity checks */
281 present = fpu.sp | fpu.dp | mpy.dsp; /* DSP and/or FPU */
282 CHK_OPT_STRICT(CONFIG_ARC_HAS_ACCL_REGS, present);
283
284 dsp_config_check();
285#endif
286 return n;
287}
288
289static char *arc_cpu_mumbojumbo(int c, struct cpuinfo_arc *info, char *buf, int len)
290{
291 struct bcr_identity ident;
292 struct bcr_timer timer;
293 struct bcr_generic bcr;
294 struct mcip_bcr mp;
295 struct bcr_actionpoint ap;
296 unsigned long vec_base;
297 int ap_num, ap_full, smart, rtt, n;
298
299 memset(info, 0, sizeof(struct cpuinfo_arc));
300
301 READ_BCR(AUX_IDENTITY, ident);
302 info->arcver = ident.family;
303
304 n = scnprintf(buf, size: len,
305 fmt: "\nIDENTITY\t: ARCVER [%#02x] ARCNUM [%#02x] CHIPID [%#4x]\n",
306 ident.family, ident.cpu_id, ident.chip_id);
307
308 if (is_isa_arcompact()) {
309 n += arcompact_mumbojumbo(c, info, buf: buf + n, len: len - n);
310 } else if (is_isa_arcv2()){
311 n += arcv2_mumbojumbo(c, info, buf: buf + n, len: len - n);
312 }
313
314 n += arc_mmu_mumbojumbo(c, buf + n, len - n);
315 n += arc_cache_mumbojumbo(c, buf + n, len - n);
316
317 READ_BCR(ARC_REG_TIMERS_BCR, timer);
318 info->t0 = timer.t0;
319 info->t1 = timer.t1;
320
321 READ_BCR(ARC_REG_MCIP_BCR, mp);
322 vec_base = read_aux_reg(r: AUX_INTR_VEC_BASE);
323
324 n += scnprintf(buf: buf + n, size: len - n,
325 fmt: "Timers\t\t: %s%s%s%s%s%s\nVector Table\t: %#lx\n",
326 IS_AVAIL1(timer.t0, "Timer0 "),
327 IS_AVAIL1(timer.t1, "Timer1 "),
328 IS_AVAIL2(timer.rtc, "RTC [UP 64-bit] ", CONFIG_ARC_TIMERS_64BIT),
329 IS_AVAIL2(mp.gfrc, "GFRC [SMP 64-bit] ", CONFIG_ARC_TIMERS_64BIT),
330 vec_base);
331
332 READ_BCR(ARC_REG_AP_BCR, ap);
333 if (ap.ver) {
334 ap_num = 2 << ap.num;
335 ap_full = !ap.min;
336 }
337
338 READ_BCR(ARC_REG_SMART_BCR, bcr);
339 smart = bcr.ver ? 1 : 0;
340
341 READ_BCR(ARC_REG_RTT_BCR, bcr);
342 rtt = bcr.ver ? 1 : 0;
343
344 if (ap.ver | smart | rtt) {
345 n += scnprintf(buf: buf + n, size: len - n, fmt: "DEBUG\t\t: %s%s",
346 IS_AVAIL1(smart, "smaRT "),
347 IS_AVAIL1(rtt, "RTT "));
348 if (ap.ver) {
349 n += scnprintf(buf: buf + n, size: len - n, fmt: "ActionPoint %d/%s",
350 ap_num,
351 ap_full ? "full":"min");
352 }
353 n += scnprintf(buf: buf + n, size: len - n, fmt: "\n");
354 }
355
356 if (info->dccm.sz || info->iccm.sz)
357 n += scnprintf(buf: buf + n, size: len - n,
358 fmt: "Extn [CCM]\t: DCCM @ %lx, %d KB / ICCM: @ %lx, %d KB\n",
359 info->dccm.base, TO_KB(info->dccm.sz),
360 info->iccm.base, TO_KB(info->iccm.sz));
361
362 return buf;
363}
364
365void chk_opt_strict(char *opt_name, bool hw_exists, bool opt_ena)
366{
367 if (hw_exists && !opt_ena)
368 pr_warn(" ! Enable %s for working apps\n", opt_name);
369 else if (!hw_exists && opt_ena)
370 panic(fmt: "Disable %s, hardware NOT present\n", opt_name);
371}
372
373void chk_opt_weak(char *opt_name, bool hw_exists, bool opt_ena)
374{
375 if (!hw_exists && opt_ena)
376 panic(fmt: "Disable %s, hardware NOT present\n", opt_name);
377}
378
379/*
380 * ISA agnostic sanity checks
381 */
382static void arc_chk_core_config(struct cpuinfo_arc *info)
383{
384 if (!info->t0)
385 panic(fmt: "Timer0 is not present!\n");
386
387 if (!info->t1)
388 panic(fmt: "Timer1 is not present!\n");
389
390#ifdef CONFIG_ARC_HAS_DCCM
391 /*
392 * DCCM can be arbit placed in hardware.
393 * Make sure its placement/sz matches what Linux is built with
394 */
395 if ((unsigned int)__arc_dccm_base != info->dccm.base)
396 panic("Linux built with incorrect DCCM Base address\n");
397
398 if (CONFIG_ARC_DCCM_SZ * SZ_1K != info->dccm.sz)
399 panic("Linux built with incorrect DCCM Size\n");
400#endif
401
402#ifdef CONFIG_ARC_HAS_ICCM
403 if (CONFIG_ARC_ICCM_SZ * SZ_1K != info->iccm.sz)
404 panic("Linux built with incorrect ICCM Size\n");
405#endif
406}
407
408/*
409 * Initialize and setup the processor core
410 * This is called by all the CPUs thus should not do special case stuff
411 * such as only for boot CPU etc
412 */
413
414void setup_processor(void)
415{
416 struct cpuinfo_arc info;
417 int c = smp_processor_id();
418 char str[512];
419
420 pr_info("%s", arc_cpu_mumbojumbo(c, &info, str, sizeof(str)));
421 pr_info("%s", arc_platform_smp_cpuinfo());
422
423 arc_chk_core_config(info: &info);
424
425 arc_init_IRQ();
426 arc_mmu_init();
427 arc_cache_init();
428
429}
430
431static inline bool uboot_arg_invalid(unsigned long addr)
432{
433 /*
434 * Check that it is a untranslated address (although MMU is not enabled
435 * yet, it being a high address ensures this is not by fluke)
436 */
437 if (addr < PAGE_OFFSET)
438 return true;
439
440 /* Check that address doesn't clobber resident kernel image */
441 return addr >= (unsigned long)_stext && addr <= (unsigned long)_end;
442}
443
444#define IGNORE_ARGS "Ignore U-boot args: "
445
446/* uboot_tag values for U-boot - kernel ABI revision 0; see head.S */
447#define UBOOT_TAG_NONE 0
448#define UBOOT_TAG_CMDLINE 1
449#define UBOOT_TAG_DTB 2
450/* We always pass 0 as magic from U-boot */
451#define UBOOT_MAGIC_VALUE 0
452
453void __init handle_uboot_args(void)
454{
455 bool use_embedded_dtb = true;
456 bool append_cmdline = false;
457
458 /* check that we know this tag */
459 if (uboot_tag != UBOOT_TAG_NONE &&
460 uboot_tag != UBOOT_TAG_CMDLINE &&
461 uboot_tag != UBOOT_TAG_DTB) {
462 pr_warn(IGNORE_ARGS "invalid uboot tag: '%08x'\n", uboot_tag);
463 goto ignore_uboot_args;
464 }
465
466 if (uboot_magic != UBOOT_MAGIC_VALUE) {
467 pr_warn(IGNORE_ARGS "non zero uboot magic\n");
468 goto ignore_uboot_args;
469 }
470
471 if (uboot_tag != UBOOT_TAG_NONE &&
472 uboot_arg_invalid(addr: (unsigned long)uboot_arg)) {
473 pr_warn(IGNORE_ARGS "invalid uboot arg: '%px'\n", uboot_arg);
474 goto ignore_uboot_args;
475 }
476
477 /* see if U-boot passed an external Device Tree blob */
478 if (uboot_tag == UBOOT_TAG_DTB) {
479 machine_desc = setup_machine_fdt((void *)uboot_arg);
480
481 /* external Device Tree blob is invalid - use embedded one */
482 use_embedded_dtb = !machine_desc;
483 }
484
485 if (uboot_tag == UBOOT_TAG_CMDLINE)
486 append_cmdline = true;
487
488ignore_uboot_args:
489
490 if (use_embedded_dtb) {
491 machine_desc = setup_machine_fdt(__dtb_start);
492 if (!machine_desc)
493 panic(fmt: "Embedded DT invalid\n");
494 }
495
496 /*
497 * NOTE: @boot_command_line is populated by setup_machine_fdt() so this
498 * append processing can only happen after.
499 */
500 if (append_cmdline) {
501 /* Ensure a whitespace between the 2 cmdlines */
502 strlcat(p: boot_command_line, q: " ", COMMAND_LINE_SIZE);
503 strlcat(p: boot_command_line, q: uboot_arg, COMMAND_LINE_SIZE);
504 }
505}
506
507void __init setup_arch(char **cmdline_p)
508{
509 handle_uboot_args();
510
511 /* Save unparsed command line copy for /proc/cmdline */
512 *cmdline_p = boot_command_line;
513
514 /* To force early parsing of things like mem=xxx */
515 parse_early_param();
516
517 /* Platform/board specific: e.g. early console registration */
518 if (machine_desc->init_early)
519 machine_desc->init_early();
520
521 smp_init_cpus();
522
523 setup_processor();
524 setup_arch_memory();
525
526 /* copy flat DT out of .init and then unflatten it */
527 unflatten_and_copy_device_tree();
528
529 /* Can be issue if someone passes cmd line arg "ro"
530 * But that is unlikely so keeping it as it is
531 */
532 root_mountflags &= ~MS_RDONLY;
533
534 arc_unwind_init();
535}
536
537/*
538 * Called from start_kernel() - boot CPU only
539 */
540void __init time_init(void)
541{
542 of_clk_init(NULL);
543 timer_probe();
544}
545
546static int __init customize_machine(void)
547{
548 if (machine_desc->init_machine)
549 machine_desc->init_machine();
550
551 return 0;
552}
553arch_initcall(customize_machine);
554
555static int __init init_late_machine(void)
556{
557 if (machine_desc->init_late)
558 machine_desc->init_late();
559
560 return 0;
561}
562late_initcall(init_late_machine);
563/*
564 * Get CPU information for use by the procfs.
565 */
566
567#define cpu_to_ptr(c) ((void *)(0xFFFF0000 | (unsigned int)(c)))
568#define ptr_to_cpu(p) (~0xFFFF0000UL & (unsigned int)(p))
569
570static int show_cpuinfo(struct seq_file *m, void *v)
571{
572 char *str;
573 int cpu_id = ptr_to_cpu(v);
574 struct device *cpu_dev = get_cpu_device(cpu: cpu_id);
575 struct cpuinfo_arc info;
576 struct clk *cpu_clk;
577 unsigned long freq = 0;
578
579 if (!cpu_online(cpu: cpu_id)) {
580 seq_printf(m, fmt: "processor [%d]\t: Offline\n", cpu_id);
581 goto done;
582 }
583
584 str = (char *)__get_free_page(GFP_KERNEL);
585 if (!str)
586 goto done;
587
588 seq_printf(m, fmt: arc_cpu_mumbojumbo(c: cpu_id, info: &info, buf: str, PAGE_SIZE));
589
590 cpu_clk = clk_get(dev: cpu_dev, NULL);
591 if (IS_ERR(ptr: cpu_clk)) {
592 seq_printf(m, fmt: "CPU speed \t: Cannot get clock for processor [%d]\n",
593 cpu_id);
594 } else {
595 freq = clk_get_rate(clk: cpu_clk);
596 }
597 if (freq)
598 seq_printf(m, fmt: "CPU speed\t: %lu.%02lu Mhz\n",
599 freq / 1000000, (freq / 10000) % 100);
600
601 seq_printf(m, fmt: "Bogo MIPS\t: %lu.%02lu\n",
602 loops_per_jiffy / (500000 / HZ),
603 (loops_per_jiffy / (5000 / HZ)) % 100);
604
605 seq_printf(m, fmt: arc_platform_smp_cpuinfo());
606
607 free_page((unsigned long)str);
608done:
609 seq_printf(m, fmt: "\n");
610
611 return 0;
612}
613
614static void *c_start(struct seq_file *m, loff_t *pos)
615{
616 /*
617 * Callback returns cpu-id to iterator for show routine, NULL to stop.
618 * However since NULL is also a valid cpu-id (0), we use a round-about
619 * way to pass it w/o having to kmalloc/free a 2 byte string.
620 * Encode cpu-id as 0xFFcccc, which is decoded by show routine.
621 */
622 return *pos < nr_cpu_ids ? cpu_to_ptr(*pos) : NULL;
623}
624
625static void *c_next(struct seq_file *m, void *v, loff_t *pos)
626{
627 ++*pos;
628 return c_start(m, pos);
629}
630
631static void c_stop(struct seq_file *m, void *v)
632{
633}
634
635const struct seq_operations cpuinfo_op = {
636 .start = c_start,
637 .next = c_next,
638 .stop = c_stop,
639 .show = show_cpuinfo
640};
641
642static DEFINE_PER_CPU(struct cpu, cpu_topology);
643
644static int __init topology_init(void)
645{
646 int cpu;
647
648 for_each_present_cpu(cpu)
649 register_cpu(cpu: &per_cpu(cpu_topology, cpu), num: cpu);
650
651 return 0;
652}
653
654subsys_initcall(topology_init);
655

source code of linux/arch/arc/kernel/setup.c