treewide: remove redundant IS_ERR() before error code check
[linux/fpc-iii.git] / arch / arc / kernel / setup.c
blobe1c647490f00e91069671f5aeb9871830cb9be83
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
4 */
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/clk-provider.h>
12 #include <linux/clocksource.h>
13 #include <linux/console.h>
14 #include <linux/module.h>
15 #include <linux/cpu.h>
16 #include <linux/of_fdt.h>
17 #include <linux/of.h>
18 #include <linux/cache.h>
19 #include <uapi/linux/mount.h>
20 #include <asm/sections.h>
21 #include <asm/arcregs.h>
22 #include <asm/tlb.h>
23 #include <asm/setup.h>
24 #include <asm/page.h>
25 #include <asm/irq.h>
26 #include <asm/unwind.h>
27 #include <asm/mach_desc.h>
28 #include <asm/smp.h>
30 #define FIX_PTR(x) __asm__ __volatile__(";" : "+r"(x))
32 unsigned int intr_to_DE_cnt;
34 /* Part of U-boot ABI: see head.S */
35 int __initdata uboot_tag;
36 int __initdata uboot_magic;
37 char __initdata *uboot_arg;
39 const struct machine_desc *machine_desc;
41 struct task_struct *_current_task[NR_CPUS]; /* For stack switching */
43 struct cpuinfo_arc cpuinfo_arc700[NR_CPUS];
45 static const struct id_to_str arc_legacy_rel[] = {
46 /* ID.ARCVER, Release */
47 #ifdef CONFIG_ISA_ARCOMPACT
48 { 0x34, "R4.10"},
49 { 0x35, "R4.11"},
50 #else
51 { 0x51, "R2.0" },
52 { 0x52, "R2.1" },
53 { 0x53, "R3.0" },
54 #endif
55 { 0x00, NULL }
58 static const struct id_to_str arc_cpu_rel[] = {
59 /* UARCH.MAJOR, Release */
60 { 0, "R3.10a"},
61 { 1, "R3.50a"},
62 { 0xFF, NULL }
65 static void read_decode_ccm_bcr(struct cpuinfo_arc *cpu)
67 if (is_isa_arcompact()) {
68 struct bcr_iccm_arcompact iccm;
69 struct bcr_dccm_arcompact dccm;
71 READ_BCR(ARC_REG_ICCM_BUILD, iccm);
72 if (iccm.ver) {
73 cpu->iccm.sz = 4096 << iccm.sz; /* 8K to 512K */
74 cpu->iccm.base_addr = iccm.base << 16;
77 READ_BCR(ARC_REG_DCCM_BUILD, dccm);
78 if (dccm.ver) {
79 unsigned long base;
80 cpu->dccm.sz = 2048 << dccm.sz; /* 2K to 256K */
82 base = read_aux_reg(ARC_REG_DCCM_BASE_BUILD);
83 cpu->dccm.base_addr = base & ~0xF;
85 } else {
86 struct bcr_iccm_arcv2 iccm;
87 struct bcr_dccm_arcv2 dccm;
88 unsigned long region;
90 READ_BCR(ARC_REG_ICCM_BUILD, iccm);
91 if (iccm.ver) {
92 cpu->iccm.sz = 256 << iccm.sz00; /* 512B to 16M */
93 if (iccm.sz00 == 0xF && iccm.sz01 > 0)
94 cpu->iccm.sz <<= iccm.sz01;
96 region = read_aux_reg(ARC_REG_AUX_ICCM);
97 cpu->iccm.base_addr = region & 0xF0000000;
100 READ_BCR(ARC_REG_DCCM_BUILD, dccm);
101 if (dccm.ver) {
102 cpu->dccm.sz = 256 << dccm.sz0;
103 if (dccm.sz0 == 0xF && dccm.sz1 > 0)
104 cpu->dccm.sz <<= dccm.sz1;
106 region = read_aux_reg(ARC_REG_AUX_DCCM);
107 cpu->dccm.base_addr = region & 0xF0000000;
112 static void decode_arc_core(struct cpuinfo_arc *cpu)
114 struct bcr_uarch_build_arcv2 uarch;
115 const struct id_to_str *tbl;
118 * Up until (including) the first core4 release (0x54) things were
119 * simple: AUX IDENTITY.ARCVER was sufficient to identify arc family
120 * and release: 0x50 to 0x53 was HS38, 0x54 was HS48 (dual issue)
123 if (cpu->core.family < 0x54) { /* includes arc700 */
125 for (tbl = &arc_legacy_rel[0]; tbl->id != 0; tbl++) {
126 if (cpu->core.family == tbl->id) {
127 cpu->release = tbl->str;
128 break;
132 if (is_isa_arcompact())
133 cpu->name = "ARC700";
134 else if (tbl->str)
135 cpu->name = "HS38";
136 else
137 cpu->name = cpu->release = "Unknown";
139 return;
143 * However the subsequent HS release (same 0x54) allow HS38 or HS48
144 * configurations and encode this info in a different BCR.
145 * The BCR was introduced in 0x54 so can't be read unconditionally.
148 READ_BCR(ARC_REG_MICRO_ARCH_BCR, uarch);
150 if (uarch.prod == 4) {
151 cpu->name = "HS48";
152 cpu->extn.dual = 1;
154 } else {
155 cpu->name = "HS38";
158 for (tbl = &arc_cpu_rel[0]; tbl->id != 0xFF; tbl++) {
159 if (uarch.maj == tbl->id) {
160 cpu->release = tbl->str;
161 break;
166 static void read_arc_build_cfg_regs(void)
168 struct bcr_timer timer;
169 struct bcr_generic bcr;
170 struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()];
171 struct bcr_isa_arcv2 isa;
172 struct bcr_actionpoint ap;
174 FIX_PTR(cpu);
176 READ_BCR(AUX_IDENTITY, cpu->core);
177 decode_arc_core(cpu);
179 READ_BCR(ARC_REG_TIMERS_BCR, timer);
180 cpu->extn.timer0 = timer.t0;
181 cpu->extn.timer1 = timer.t1;
182 cpu->extn.rtc = timer.rtc;
184 cpu->vec_base = read_aux_reg(AUX_INTR_VEC_BASE);
186 READ_BCR(ARC_REG_MUL_BCR, cpu->extn_mpy);
188 /* Read CCM BCRs for boot reporting even if not enabled in Kconfig */
189 read_decode_ccm_bcr(cpu);
191 read_decode_mmu_bcr();
192 read_decode_cache_bcr();
194 if (is_isa_arcompact()) {
195 struct bcr_fp_arcompact sp, dp;
196 struct bcr_bpu_arcompact bpu;
198 READ_BCR(ARC_REG_FP_BCR, sp);
199 READ_BCR(ARC_REG_DPFP_BCR, dp);
200 cpu->extn.fpu_sp = sp.ver ? 1 : 0;
201 cpu->extn.fpu_dp = dp.ver ? 1 : 0;
203 READ_BCR(ARC_REG_BPU_BCR, bpu);
204 cpu->bpu.ver = bpu.ver;
205 cpu->bpu.full = bpu.fam ? 1 : 0;
206 if (bpu.ent) {
207 cpu->bpu.num_cache = 256 << (bpu.ent - 1);
208 cpu->bpu.num_pred = 256 << (bpu.ent - 1);
210 } else {
211 struct bcr_fp_arcv2 spdp;
212 struct bcr_bpu_arcv2 bpu;
214 READ_BCR(ARC_REG_FP_V2_BCR, spdp);
215 cpu->extn.fpu_sp = spdp.sp ? 1 : 0;
216 cpu->extn.fpu_dp = spdp.dp ? 1 : 0;
218 READ_BCR(ARC_REG_BPU_BCR, bpu);
219 cpu->bpu.ver = bpu.ver;
220 cpu->bpu.full = bpu.ft;
221 cpu->bpu.num_cache = 256 << bpu.bce;
222 cpu->bpu.num_pred = 2048 << bpu.pte;
223 cpu->bpu.ret_stk = 4 << bpu.rse;
225 /* if dual issue hardware, is it enabled ? */
226 if (cpu->extn.dual) {
227 unsigned int exec_ctrl;
229 READ_BCR(AUX_EXEC_CTRL, exec_ctrl);
230 cpu->extn.dual_enb = !(exec_ctrl & 1);
234 READ_BCR(ARC_REG_AP_BCR, ap);
235 if (ap.ver) {
236 cpu->extn.ap_num = 2 << ap.num;
237 cpu->extn.ap_full = !ap.min;
240 READ_BCR(ARC_REG_SMART_BCR, bcr);
241 cpu->extn.smart = bcr.ver ? 1 : 0;
243 READ_BCR(ARC_REG_RTT_BCR, bcr);
244 cpu->extn.rtt = bcr.ver ? 1 : 0;
246 READ_BCR(ARC_REG_ISA_CFG_BCR, isa);
248 /* some hacks for lack of feature BCR info in old ARC700 cores */
249 if (is_isa_arcompact()) {
250 if (!isa.ver) /* ISA BCR absent, use Kconfig info */
251 cpu->isa.atomic = IS_ENABLED(CONFIG_ARC_HAS_LLSC);
252 else {
253 /* ARC700_BUILD only has 2 bits of isa info */
254 struct bcr_generic bcr = *(struct bcr_generic *)&isa;
255 cpu->isa.atomic = bcr.info & 1;
258 cpu->isa.be = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
260 /* there's no direct way to distinguish 750 vs. 770 */
261 if (unlikely(cpu->core.family < 0x34 || cpu->mmu.ver < 3))
262 cpu->name = "ARC750";
263 } else {
264 cpu->isa = isa;
268 static char *arc_cpu_mumbojumbo(int cpu_id, char *buf, int len)
270 struct cpuinfo_arc *cpu = &cpuinfo_arc700[cpu_id];
271 struct bcr_identity *core = &cpu->core;
272 char mpy_opt[16];
273 int n = 0;
275 FIX_PTR(cpu);
277 n += scnprintf(buf + n, len - n,
278 "\nIDENTITY\t: ARCVER [%#02x] ARCNUM [%#02x] CHIPID [%#4x]\n",
279 core->family, core->cpu_id, core->chip_id);
281 n += scnprintf(buf + n, len - n, "processor [%d]\t: %s %s (%s ISA) %s%s%s\n",
282 cpu_id, cpu->name, cpu->release,
283 is_isa_arcompact() ? "ARCompact" : "ARCv2",
284 IS_AVAIL1(cpu->isa.be, "[Big-Endian]"),
285 IS_AVAIL3(cpu->extn.dual, cpu->extn.dual_enb, " Dual-Issue "));
287 n += scnprintf(buf + n, len - n, "Timers\t\t: %s%s%s%s%s%s\nISA Extn\t: ",
288 IS_AVAIL1(cpu->extn.timer0, "Timer0 "),
289 IS_AVAIL1(cpu->extn.timer1, "Timer1 "),
290 IS_AVAIL2(cpu->extn.rtc, "RTC [UP 64-bit] ", CONFIG_ARC_TIMERS_64BIT),
291 IS_AVAIL2(cpu->extn.gfrc, "GFRC [SMP 64-bit] ", CONFIG_ARC_TIMERS_64BIT));
293 if (cpu->extn_mpy.ver) {
294 if (is_isa_arcompact()) {
295 scnprintf(mpy_opt, 16, "mpy");
296 } else {
298 int opt = 2; /* stock MPY/MPYH */
300 if (cpu->extn_mpy.dsp) /* OPT 7-9 */
301 opt = cpu->extn_mpy.dsp + 6;
303 scnprintf(mpy_opt, 16, "mpy[opt %d] ", opt);
307 n += scnprintf(buf + n, len - n, "%s%s%s%s%s%s%s%s\n",
308 IS_AVAIL2(cpu->isa.atomic, "atomic ", CONFIG_ARC_HAS_LLSC),
309 IS_AVAIL2(cpu->isa.ldd, "ll64 ", CONFIG_ARC_HAS_LL64),
310 IS_AVAIL2(cpu->isa.unalign, "unalign ", CONFIG_ARC_USE_UNALIGNED_MEM_ACCESS),
311 IS_AVAIL1(cpu->extn_mpy.ver, mpy_opt),
312 IS_AVAIL1(cpu->isa.div_rem, "div_rem "));
314 if (cpu->bpu.ver) {
315 n += scnprintf(buf + n, len - n,
316 "BPU\t\t: %s%s match, cache:%d, Predict Table:%d Return stk: %d",
317 IS_AVAIL1(cpu->bpu.full, "full"),
318 IS_AVAIL1(!cpu->bpu.full, "partial"),
319 cpu->bpu.num_cache, cpu->bpu.num_pred, cpu->bpu.ret_stk);
321 if (is_isa_arcv2()) {
322 struct bcr_lpb lpb;
324 READ_BCR(ARC_REG_LPB_BUILD, lpb);
325 if (lpb.ver) {
326 unsigned int ctl;
327 ctl = read_aux_reg(ARC_REG_LPB_CTRL);
329 n += scnprintf(buf + n, len - n, " Loop Buffer:%d %s",
330 lpb.entries,
331 IS_DISABLED_RUN(!ctl));
334 n += scnprintf(buf + n, len - n, "\n");
337 return buf;
340 static char *arc_extn_mumbojumbo(int cpu_id, char *buf, int len)
342 int n = 0;
343 struct cpuinfo_arc *cpu = &cpuinfo_arc700[cpu_id];
345 FIX_PTR(cpu);
347 n += scnprintf(buf + n, len - n, "Vector Table\t: %#x\n", cpu->vec_base);
349 if (cpu->extn.fpu_sp || cpu->extn.fpu_dp)
350 n += scnprintf(buf + n, len - n, "FPU\t\t: %s%s\n",
351 IS_AVAIL1(cpu->extn.fpu_sp, "SP "),
352 IS_AVAIL1(cpu->extn.fpu_dp, "DP "));
354 if (cpu->extn.ap_num | cpu->extn.smart | cpu->extn.rtt) {
355 n += scnprintf(buf + n, len - n, "DEBUG\t\t: %s%s",
356 IS_AVAIL1(cpu->extn.smart, "smaRT "),
357 IS_AVAIL1(cpu->extn.rtt, "RTT "));
358 if (cpu->extn.ap_num) {
359 n += scnprintf(buf + n, len - n, "ActionPoint %d/%s",
360 cpu->extn.ap_num,
361 cpu->extn.ap_full ? "full":"min");
363 n += scnprintf(buf + n, len - n, "\n");
366 if (cpu->dccm.sz || cpu->iccm.sz)
367 n += scnprintf(buf + n, len - n, "Extn [CCM]\t: DCCM @ %x, %d KB / ICCM: @ %x, %d KB\n",
368 cpu->dccm.base_addr, TO_KB(cpu->dccm.sz),
369 cpu->iccm.base_addr, TO_KB(cpu->iccm.sz));
371 if (is_isa_arcv2()) {
373 /* Error Protection: ECC/Parity */
374 struct bcr_erp erp;
375 READ_BCR(ARC_REG_ERP_BUILD, erp);
377 if (erp.ver) {
378 struct ctl_erp ctl;
379 READ_BCR(ARC_REG_ERP_CTRL, ctl);
381 /* inverted bits: 0 means enabled */
382 n += scnprintf(buf + n, len - n, "Extn [ECC]\t: %s%s%s%s%s%s\n",
383 IS_AVAIL3(erp.ic, !ctl.dpi, "IC "),
384 IS_AVAIL3(erp.dc, !ctl.dpd, "DC "),
385 IS_AVAIL3(erp.mmu, !ctl.mpd, "MMU "));
389 return buf;
392 static void arc_chk_core_config(void)
394 struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()];
395 int saved = 0, present = 0;
396 char *opt_nm = NULL;
398 if (!cpu->extn.timer0)
399 panic("Timer0 is not present!\n");
401 if (!cpu->extn.timer1)
402 panic("Timer1 is not present!\n");
404 #ifdef CONFIG_ARC_HAS_DCCM
406 * DCCM can be arbit placed in hardware.
407 * Make sure it's placement/sz matches what Linux is built with
409 if ((unsigned int)__arc_dccm_base != cpu->dccm.base_addr)
410 panic("Linux built with incorrect DCCM Base address\n");
412 if (CONFIG_ARC_DCCM_SZ != cpu->dccm.sz)
413 panic("Linux built with incorrect DCCM Size\n");
414 #endif
416 #ifdef CONFIG_ARC_HAS_ICCM
417 if (CONFIG_ARC_ICCM_SZ != cpu->iccm.sz)
418 panic("Linux built with incorrect ICCM Size\n");
419 #endif
422 * FP hardware/software config sanity
423 * -If hardware present, kernel needs to save/restore FPU state
424 * -If not, it will crash trying to save/restore the non-existant regs
427 if (is_isa_arcompact()) {
428 opt_nm = "CONFIG_ARC_FPU_SAVE_RESTORE";
429 saved = IS_ENABLED(CONFIG_ARC_FPU_SAVE_RESTORE);
431 /* only DPDP checked since SP has no arch visible regs */
432 present = cpu->extn.fpu_dp;
433 } else {
434 opt_nm = "CONFIG_ARC_HAS_ACCL_REGS";
435 saved = IS_ENABLED(CONFIG_ARC_HAS_ACCL_REGS);
437 /* Accumulator Low:High pair (r58:59) present if DSP MPY or FPU */
438 present = cpu->extn_mpy.dsp | cpu->extn.fpu_sp | cpu->extn.fpu_dp;
441 if (present && !saved)
442 pr_warn("Enable %s for working apps\n", opt_nm);
443 else if (!present && saved)
444 panic("Disable %s, hardware NOT present\n", opt_nm);
448 * Initialize and setup the processor core
449 * This is called by all the CPUs thus should not do special case stuff
450 * such as only for boot CPU etc
453 void setup_processor(void)
455 char str[512];
456 int cpu_id = smp_processor_id();
458 read_arc_build_cfg_regs();
459 arc_init_IRQ();
461 pr_info("%s", arc_cpu_mumbojumbo(cpu_id, str, sizeof(str)));
463 arc_mmu_init();
464 arc_cache_init();
466 pr_info("%s", arc_extn_mumbojumbo(cpu_id, str, sizeof(str)));
467 pr_info("%s", arc_platform_smp_cpuinfo());
469 arc_chk_core_config();
472 static inline bool uboot_arg_invalid(unsigned long addr)
475 * Check that it is a untranslated address (although MMU is not enabled
476 * yet, it being a high address ensures this is not by fluke)
478 if (addr < PAGE_OFFSET)
479 return true;
481 /* Check that address doesn't clobber resident kernel image */
482 return addr >= (unsigned long)_stext && addr <= (unsigned long)_end;
485 #define IGNORE_ARGS "Ignore U-boot args: "
487 /* uboot_tag values for U-boot - kernel ABI revision 0; see head.S */
488 #define UBOOT_TAG_NONE 0
489 #define UBOOT_TAG_CMDLINE 1
490 #define UBOOT_TAG_DTB 2
491 /* We always pass 0 as magic from U-boot */
492 #define UBOOT_MAGIC_VALUE 0
494 void __init handle_uboot_args(void)
496 bool use_embedded_dtb = true;
497 bool append_cmdline = false;
499 /* check that we know this tag */
500 if (uboot_tag != UBOOT_TAG_NONE &&
501 uboot_tag != UBOOT_TAG_CMDLINE &&
502 uboot_tag != UBOOT_TAG_DTB) {
503 pr_warn(IGNORE_ARGS "invalid uboot tag: '%08x'\n", uboot_tag);
504 goto ignore_uboot_args;
507 if (uboot_magic != UBOOT_MAGIC_VALUE) {
508 pr_warn(IGNORE_ARGS "non zero uboot magic\n");
509 goto ignore_uboot_args;
512 if (uboot_tag != UBOOT_TAG_NONE &&
513 uboot_arg_invalid((unsigned long)uboot_arg)) {
514 pr_warn(IGNORE_ARGS "invalid uboot arg: '%px'\n", uboot_arg);
515 goto ignore_uboot_args;
518 /* see if U-boot passed an external Device Tree blob */
519 if (uboot_tag == UBOOT_TAG_DTB) {
520 machine_desc = setup_machine_fdt((void *)uboot_arg);
522 /* external Device Tree blob is invalid - use embedded one */
523 use_embedded_dtb = !machine_desc;
526 if (uboot_tag == UBOOT_TAG_CMDLINE)
527 append_cmdline = true;
529 ignore_uboot_args:
531 if (use_embedded_dtb) {
532 machine_desc = setup_machine_fdt(__dtb_start);
533 if (!machine_desc)
534 panic("Embedded DT invalid\n");
538 * NOTE: @boot_command_line is populated by setup_machine_fdt() so this
539 * append processing can only happen after.
541 if (append_cmdline) {
542 /* Ensure a whitespace between the 2 cmdlines */
543 strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
544 strlcat(boot_command_line, uboot_arg, COMMAND_LINE_SIZE);
548 void __init setup_arch(char **cmdline_p)
550 handle_uboot_args();
552 /* Save unparsed command line copy for /proc/cmdline */
553 *cmdline_p = boot_command_line;
555 /* To force early parsing of things like mem=xxx */
556 parse_early_param();
558 /* Platform/board specific: e.g. early console registration */
559 if (machine_desc->init_early)
560 machine_desc->init_early();
562 smp_init_cpus();
564 setup_processor();
565 setup_arch_memory();
567 /* copy flat DT out of .init and then unflatten it */
568 unflatten_and_copy_device_tree();
570 /* Can be issue if someone passes cmd line arg "ro"
571 * But that is unlikely so keeping it as it is
573 root_mountflags &= ~MS_RDONLY;
575 arc_unwind_init();
579 * Called from start_kernel() - boot CPU only
581 void __init time_init(void)
583 of_clk_init(NULL);
584 timer_probe();
587 static int __init customize_machine(void)
589 if (machine_desc->init_machine)
590 machine_desc->init_machine();
592 return 0;
594 arch_initcall(customize_machine);
596 static int __init init_late_machine(void)
598 if (machine_desc->init_late)
599 machine_desc->init_late();
601 return 0;
603 late_initcall(init_late_machine);
605 * Get CPU information for use by the procfs.
608 #define cpu_to_ptr(c) ((void *)(0xFFFF0000 | (unsigned int)(c)))
609 #define ptr_to_cpu(p) (~0xFFFF0000UL & (unsigned int)(p))
611 static int show_cpuinfo(struct seq_file *m, void *v)
613 char *str;
614 int cpu_id = ptr_to_cpu(v);
615 struct device *cpu_dev = get_cpu_device(cpu_id);
616 struct clk *cpu_clk;
617 unsigned long freq = 0;
619 if (!cpu_online(cpu_id)) {
620 seq_printf(m, "processor [%d]\t: Offline\n", cpu_id);
621 goto done;
624 str = (char *)__get_free_page(GFP_KERNEL);
625 if (!str)
626 goto done;
628 seq_printf(m, arc_cpu_mumbojumbo(cpu_id, str, PAGE_SIZE));
630 cpu_clk = clk_get(cpu_dev, NULL);
631 if (IS_ERR(cpu_clk)) {
632 seq_printf(m, "CPU speed \t: Cannot get clock for processor [%d]\n",
633 cpu_id);
634 } else {
635 freq = clk_get_rate(cpu_clk);
637 if (freq)
638 seq_printf(m, "CPU speed\t: %lu.%02lu Mhz\n",
639 freq / 1000000, (freq / 10000) % 100);
641 seq_printf(m, "Bogo MIPS\t: %lu.%02lu\n",
642 loops_per_jiffy / (500000 / HZ),
643 (loops_per_jiffy / (5000 / HZ)) % 100);
645 seq_printf(m, arc_mmu_mumbojumbo(cpu_id, str, PAGE_SIZE));
646 seq_printf(m, arc_cache_mumbojumbo(cpu_id, str, PAGE_SIZE));
647 seq_printf(m, arc_extn_mumbojumbo(cpu_id, str, PAGE_SIZE));
648 seq_printf(m, arc_platform_smp_cpuinfo());
650 free_page((unsigned long)str);
651 done:
652 seq_printf(m, "\n");
654 return 0;
657 static void *c_start(struct seq_file *m, loff_t *pos)
660 * Callback returns cpu-id to iterator for show routine, NULL to stop.
661 * However since NULL is also a valid cpu-id (0), we use a round-about
662 * way to pass it w/o having to kmalloc/free a 2 byte string.
663 * Encode cpu-id as 0xFFcccc, which is decoded by show routine.
665 return *pos < nr_cpu_ids ? cpu_to_ptr(*pos) : NULL;
668 static void *c_next(struct seq_file *m, void *v, loff_t *pos)
670 ++*pos;
671 return c_start(m, pos);
674 static void c_stop(struct seq_file *m, void *v)
678 const struct seq_operations cpuinfo_op = {
679 .start = c_start,
680 .next = c_next,
681 .stop = c_stop,
682 .show = show_cpuinfo
685 static DEFINE_PER_CPU(struct cpu, cpu_topology);
687 static int __init topology_init(void)
689 int cpu;
691 for_each_present_cpu(cpu)
692 register_cpu(&per_cpu(cpu_topology, cpu), cpu);
694 return 0;
697 subsys_initcall(topology_init);