xref: /openbmc/linux/arch/arm/kernel/setup.c (revision b593bce5)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/arch/arm/kernel/setup.c
4  *
5  *  Copyright (C) 1995-2001 Russell King
6  */
7 #include <linux/efi.h>
8 #include <linux/export.h>
9 #include <linux/kernel.h>
10 #include <linux/stddef.h>
11 #include <linux/ioport.h>
12 #include <linux/delay.h>
13 #include <linux/utsname.h>
14 #include <linux/initrd.h>
15 #include <linux/console.h>
16 #include <linux/seq_file.h>
17 #include <linux/screen_info.h>
18 #include <linux/of_platform.h>
19 #include <linux/init.h>
20 #include <linux/kexec.h>
21 #include <linux/of_fdt.h>
22 #include <linux/cpu.h>
23 #include <linux/interrupt.h>
24 #include <linux/smp.h>
25 #include <linux/proc_fs.h>
26 #include <linux/memblock.h>
27 #include <linux/bug.h>
28 #include <linux/compiler.h>
29 #include <linux/sort.h>
30 #include <linux/psci.h>
31 
32 #include <asm/unified.h>
33 #include <asm/cp15.h>
34 #include <asm/cpu.h>
35 #include <asm/cputype.h>
36 #include <asm/efi.h>
37 #include <asm/elf.h>
38 #include <asm/early_ioremap.h>
39 #include <asm/fixmap.h>
40 #include <asm/procinfo.h>
41 #include <asm/psci.h>
42 #include <asm/sections.h>
43 #include <asm/setup.h>
44 #include <asm/smp_plat.h>
45 #include <asm/mach-types.h>
46 #include <asm/cacheflush.h>
47 #include <asm/cachetype.h>
48 #include <asm/tlbflush.h>
49 #include <asm/xen/hypervisor.h>
50 
51 #include <asm/prom.h>
52 #include <asm/mach/arch.h>
53 #include <asm/mach/irq.h>
54 #include <asm/mach/time.h>
55 #include <asm/system_info.h>
56 #include <asm/system_misc.h>
57 #include <asm/traps.h>
58 #include <asm/unwind.h>
59 #include <asm/memblock.h>
60 #include <asm/virt.h>
61 
62 #include "atags.h"
63 
64 
65 #if defined(CONFIG_FPE_NWFPE) || defined(CONFIG_FPE_FASTFPE)
66 char fpe_type[8];
67 
68 static int __init fpe_setup(char *line)
69 {
70 	memcpy(fpe_type, line, 8);
71 	return 1;
72 }
73 
74 __setup("fpe=", fpe_setup);
75 #endif
76 
77 extern void init_default_cache_policy(unsigned long);
78 extern void paging_init(const struct machine_desc *desc);
79 extern void early_mm_init(const struct machine_desc *);
80 extern void adjust_lowmem_bounds(void);
81 extern enum reboot_mode reboot_mode;
82 extern void setup_dma_zone(const struct machine_desc *desc);
83 
84 unsigned int processor_id;
85 EXPORT_SYMBOL(processor_id);
86 unsigned int __machine_arch_type __read_mostly;
87 EXPORT_SYMBOL(__machine_arch_type);
88 unsigned int cacheid __read_mostly;
89 EXPORT_SYMBOL(cacheid);
90 
91 unsigned int __atags_pointer __initdata;
92 
93 unsigned int system_rev;
94 EXPORT_SYMBOL(system_rev);
95 
96 const char *system_serial;
97 EXPORT_SYMBOL(system_serial);
98 
99 unsigned int system_serial_low;
100 EXPORT_SYMBOL(system_serial_low);
101 
102 unsigned int system_serial_high;
103 EXPORT_SYMBOL(system_serial_high);
104 
105 unsigned int elf_hwcap __read_mostly;
106 EXPORT_SYMBOL(elf_hwcap);
107 
108 unsigned int elf_hwcap2 __read_mostly;
109 EXPORT_SYMBOL(elf_hwcap2);
110 
111 
112 #ifdef MULTI_CPU
113 struct processor processor __ro_after_init;
114 #if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
115 struct processor *cpu_vtable[NR_CPUS] = {
116 	[0] = &processor,
117 };
118 #endif
119 #endif
120 #ifdef MULTI_TLB
121 struct cpu_tlb_fns cpu_tlb __ro_after_init;
122 #endif
123 #ifdef MULTI_USER
124 struct cpu_user_fns cpu_user __ro_after_init;
125 #endif
126 #ifdef MULTI_CACHE
127 struct cpu_cache_fns cpu_cache __ro_after_init;
128 #endif
129 #ifdef CONFIG_OUTER_CACHE
130 struct outer_cache_fns outer_cache __ro_after_init;
131 EXPORT_SYMBOL(outer_cache);
132 #endif
133 
134 /*
135  * Cached cpu_architecture() result for use by assembler code.
136  * C code should use the cpu_architecture() function instead of accessing this
137  * variable directly.
138  */
139 int __cpu_architecture __read_mostly = CPU_ARCH_UNKNOWN;
140 
141 struct stack {
142 	u32 irq[3];
143 	u32 abt[3];
144 	u32 und[3];
145 	u32 fiq[3];
146 } ____cacheline_aligned;
147 
148 #ifndef CONFIG_CPU_V7M
149 static struct stack stacks[NR_CPUS];
150 #endif
151 
152 char elf_platform[ELF_PLATFORM_SIZE];
153 EXPORT_SYMBOL(elf_platform);
154 
155 static const char *cpu_name;
156 static const char *machine_name;
157 static char __initdata cmd_line[COMMAND_LINE_SIZE];
158 const struct machine_desc *machine_desc __initdata;
159 
160 static union { char c[4]; unsigned long l; } endian_test __initdata = { { 'l', '?', '?', 'b' } };
161 #define ENDIANNESS ((char)endian_test.l)
162 
163 DEFINE_PER_CPU(struct cpuinfo_arm, cpu_data);
164 
165 /*
166  * Standard memory resources
167  */
168 static struct resource mem_res[] = {
169 	{
170 		.name = "Video RAM",
171 		.start = 0,
172 		.end = 0,
173 		.flags = IORESOURCE_MEM
174 	},
175 	{
176 		.name = "Kernel code",
177 		.start = 0,
178 		.end = 0,
179 		.flags = IORESOURCE_SYSTEM_RAM
180 	},
181 	{
182 		.name = "Kernel data",
183 		.start = 0,
184 		.end = 0,
185 		.flags = IORESOURCE_SYSTEM_RAM
186 	}
187 };
188 
189 #define video_ram   mem_res[0]
190 #define kernel_code mem_res[1]
191 #define kernel_data mem_res[2]
192 
193 static struct resource io_res[] = {
194 	{
195 		.name = "reserved",
196 		.start = 0x3bc,
197 		.end = 0x3be,
198 		.flags = IORESOURCE_IO | IORESOURCE_BUSY
199 	},
200 	{
201 		.name = "reserved",
202 		.start = 0x378,
203 		.end = 0x37f,
204 		.flags = IORESOURCE_IO | IORESOURCE_BUSY
205 	},
206 	{
207 		.name = "reserved",
208 		.start = 0x278,
209 		.end = 0x27f,
210 		.flags = IORESOURCE_IO | IORESOURCE_BUSY
211 	}
212 };
213 
214 #define lp0 io_res[0]
215 #define lp1 io_res[1]
216 #define lp2 io_res[2]
217 
218 static const char *proc_arch[] = {
219 	"undefined/unknown",
220 	"3",
221 	"4",
222 	"4T",
223 	"5",
224 	"5T",
225 	"5TE",
226 	"5TEJ",
227 	"6TEJ",
228 	"7",
229 	"7M",
230 	"?(12)",
231 	"?(13)",
232 	"?(14)",
233 	"?(15)",
234 	"?(16)",
235 	"?(17)",
236 };
237 
238 #ifdef CONFIG_CPU_V7M
239 static int __get_cpu_architecture(void)
240 {
241 	return CPU_ARCH_ARMv7M;
242 }
243 #else
244 static int __get_cpu_architecture(void)
245 {
246 	int cpu_arch;
247 
248 	if ((read_cpuid_id() & 0x0008f000) == 0) {
249 		cpu_arch = CPU_ARCH_UNKNOWN;
250 	} else if ((read_cpuid_id() & 0x0008f000) == 0x00007000) {
251 		cpu_arch = (read_cpuid_id() & (1 << 23)) ? CPU_ARCH_ARMv4T : CPU_ARCH_ARMv3;
252 	} else if ((read_cpuid_id() & 0x00080000) == 0x00000000) {
253 		cpu_arch = (read_cpuid_id() >> 16) & 7;
254 		if (cpu_arch)
255 			cpu_arch += CPU_ARCH_ARMv3;
256 	} else if ((read_cpuid_id() & 0x000f0000) == 0x000f0000) {
257 		/* Revised CPUID format. Read the Memory Model Feature
258 		 * Register 0 and check for VMSAv7 or PMSAv7 */
259 		unsigned int mmfr0 = read_cpuid_ext(CPUID_EXT_MMFR0);
260 		if ((mmfr0 & 0x0000000f) >= 0x00000003 ||
261 		    (mmfr0 & 0x000000f0) >= 0x00000030)
262 			cpu_arch = CPU_ARCH_ARMv7;
263 		else if ((mmfr0 & 0x0000000f) == 0x00000002 ||
264 			 (mmfr0 & 0x000000f0) == 0x00000020)
265 			cpu_arch = CPU_ARCH_ARMv6;
266 		else
267 			cpu_arch = CPU_ARCH_UNKNOWN;
268 	} else
269 		cpu_arch = CPU_ARCH_UNKNOWN;
270 
271 	return cpu_arch;
272 }
273 #endif
274 
275 int __pure cpu_architecture(void)
276 {
277 	BUG_ON(__cpu_architecture == CPU_ARCH_UNKNOWN);
278 
279 	return __cpu_architecture;
280 }
281 
282 static int cpu_has_aliasing_icache(unsigned int arch)
283 {
284 	int aliasing_icache;
285 	unsigned int id_reg, num_sets, line_size;
286 
287 	/* PIPT caches never alias. */
288 	if (icache_is_pipt())
289 		return 0;
290 
291 	/* arch specifies the register format */
292 	switch (arch) {
293 	case CPU_ARCH_ARMv7:
294 		set_csselr(CSSELR_ICACHE | CSSELR_L1);
295 		isb();
296 		id_reg = read_ccsidr();
297 		line_size = 4 << ((id_reg & 0x7) + 2);
298 		num_sets = ((id_reg >> 13) & 0x7fff) + 1;
299 		aliasing_icache = (line_size * num_sets) > PAGE_SIZE;
300 		break;
301 	case CPU_ARCH_ARMv6:
302 		aliasing_icache = read_cpuid_cachetype() & (1 << 11);
303 		break;
304 	default:
305 		/* I-cache aliases will be handled by D-cache aliasing code */
306 		aliasing_icache = 0;
307 	}
308 
309 	return aliasing_icache;
310 }
311 
312 static void __init cacheid_init(void)
313 {
314 	unsigned int arch = cpu_architecture();
315 
316 	if (arch >= CPU_ARCH_ARMv6) {
317 		unsigned int cachetype = read_cpuid_cachetype();
318 
319 		if ((arch == CPU_ARCH_ARMv7M) && !(cachetype & 0xf000f)) {
320 			cacheid = 0;
321 		} else if ((cachetype & (7 << 29)) == 4 << 29) {
322 			/* ARMv7 register format */
323 			arch = CPU_ARCH_ARMv7;
324 			cacheid = CACHEID_VIPT_NONALIASING;
325 			switch (cachetype & (3 << 14)) {
326 			case (1 << 14):
327 				cacheid |= CACHEID_ASID_TAGGED;
328 				break;
329 			case (3 << 14):
330 				cacheid |= CACHEID_PIPT;
331 				break;
332 			}
333 		} else {
334 			arch = CPU_ARCH_ARMv6;
335 			if (cachetype & (1 << 23))
336 				cacheid = CACHEID_VIPT_ALIASING;
337 			else
338 				cacheid = CACHEID_VIPT_NONALIASING;
339 		}
340 		if (cpu_has_aliasing_icache(arch))
341 			cacheid |= CACHEID_VIPT_I_ALIASING;
342 	} else {
343 		cacheid = CACHEID_VIVT;
344 	}
345 
346 	pr_info("CPU: %s data cache, %s instruction cache\n",
347 		cache_is_vivt() ? "VIVT" :
348 		cache_is_vipt_aliasing() ? "VIPT aliasing" :
349 		cache_is_vipt_nonaliasing() ? "PIPT / VIPT nonaliasing" : "unknown",
350 		cache_is_vivt() ? "VIVT" :
351 		icache_is_vivt_asid_tagged() ? "VIVT ASID tagged" :
352 		icache_is_vipt_aliasing() ? "VIPT aliasing" :
353 		icache_is_pipt() ? "PIPT" :
354 		cache_is_vipt_nonaliasing() ? "VIPT nonaliasing" : "unknown");
355 }
356 
357 /*
358  * These functions re-use the assembly code in head.S, which
359  * already provide the required functionality.
360  */
361 extern struct proc_info_list *lookup_processor_type(unsigned int);
362 
363 void __init early_print(const char *str, ...)
364 {
365 	extern void printascii(const char *);
366 	char buf[256];
367 	va_list ap;
368 
369 	va_start(ap, str);
370 	vsnprintf(buf, sizeof(buf), str, ap);
371 	va_end(ap);
372 
373 #ifdef CONFIG_DEBUG_LL
374 	printascii(buf);
375 #endif
376 	printk("%s", buf);
377 }
378 
379 #ifdef CONFIG_ARM_PATCH_IDIV
380 
381 static inline u32 __attribute_const__ sdiv_instruction(void)
382 {
383 	if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
384 		/* "sdiv r0, r0, r1" */
385 		u32 insn = __opcode_thumb32_compose(0xfb90, 0xf0f1);
386 		return __opcode_to_mem_thumb32(insn);
387 	}
388 
389 	/* "sdiv r0, r0, r1" */
390 	return __opcode_to_mem_arm(0xe710f110);
391 }
392 
393 static inline u32 __attribute_const__ udiv_instruction(void)
394 {
395 	if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
396 		/* "udiv r0, r0, r1" */
397 		u32 insn = __opcode_thumb32_compose(0xfbb0, 0xf0f1);
398 		return __opcode_to_mem_thumb32(insn);
399 	}
400 
401 	/* "udiv r0, r0, r1" */
402 	return __opcode_to_mem_arm(0xe730f110);
403 }
404 
405 static inline u32 __attribute_const__ bx_lr_instruction(void)
406 {
407 	if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
408 		/* "bx lr; nop" */
409 		u32 insn = __opcode_thumb32_compose(0x4770, 0x46c0);
410 		return __opcode_to_mem_thumb32(insn);
411 	}
412 
413 	/* "bx lr" */
414 	return __opcode_to_mem_arm(0xe12fff1e);
415 }
416 
417 static void __init patch_aeabi_idiv(void)
418 {
419 	extern void __aeabi_uidiv(void);
420 	extern void __aeabi_idiv(void);
421 	uintptr_t fn_addr;
422 	unsigned int mask;
423 
424 	mask = IS_ENABLED(CONFIG_THUMB2_KERNEL) ? HWCAP_IDIVT : HWCAP_IDIVA;
425 	if (!(elf_hwcap & mask))
426 		return;
427 
428 	pr_info("CPU: div instructions available: patching division code\n");
429 
430 	fn_addr = ((uintptr_t)&__aeabi_uidiv) & ~1;
431 	asm ("" : "+g" (fn_addr));
432 	((u32 *)fn_addr)[0] = udiv_instruction();
433 	((u32 *)fn_addr)[1] = bx_lr_instruction();
434 	flush_icache_range(fn_addr, fn_addr + 8);
435 
436 	fn_addr = ((uintptr_t)&__aeabi_idiv) & ~1;
437 	asm ("" : "+g" (fn_addr));
438 	((u32 *)fn_addr)[0] = sdiv_instruction();
439 	((u32 *)fn_addr)[1] = bx_lr_instruction();
440 	flush_icache_range(fn_addr, fn_addr + 8);
441 }
442 
443 #else
444 static inline void patch_aeabi_idiv(void) { }
445 #endif
446 
447 static void __init cpuid_init_hwcaps(void)
448 {
449 	int block;
450 	u32 isar5;
451 
452 	if (cpu_architecture() < CPU_ARCH_ARMv7)
453 		return;
454 
455 	block = cpuid_feature_extract(CPUID_EXT_ISAR0, 24);
456 	if (block >= 2)
457 		elf_hwcap |= HWCAP_IDIVA;
458 	if (block >= 1)
459 		elf_hwcap |= HWCAP_IDIVT;
460 
461 	/* LPAE implies atomic ldrd/strd instructions */
462 	block = cpuid_feature_extract(CPUID_EXT_MMFR0, 0);
463 	if (block >= 5)
464 		elf_hwcap |= HWCAP_LPAE;
465 
466 	/* check for supported v8 Crypto instructions */
467 	isar5 = read_cpuid_ext(CPUID_EXT_ISAR5);
468 
469 	block = cpuid_feature_extract_field(isar5, 4);
470 	if (block >= 2)
471 		elf_hwcap2 |= HWCAP2_PMULL;
472 	if (block >= 1)
473 		elf_hwcap2 |= HWCAP2_AES;
474 
475 	block = cpuid_feature_extract_field(isar5, 8);
476 	if (block >= 1)
477 		elf_hwcap2 |= HWCAP2_SHA1;
478 
479 	block = cpuid_feature_extract_field(isar5, 12);
480 	if (block >= 1)
481 		elf_hwcap2 |= HWCAP2_SHA2;
482 
483 	block = cpuid_feature_extract_field(isar5, 16);
484 	if (block >= 1)
485 		elf_hwcap2 |= HWCAP2_CRC32;
486 }
487 
488 static void __init elf_hwcap_fixup(void)
489 {
490 	unsigned id = read_cpuid_id();
491 
492 	/*
493 	 * HWCAP_TLS is available only on 1136 r1p0 and later,
494 	 * see also kuser_get_tls_init.
495 	 */
496 	if (read_cpuid_part() == ARM_CPU_PART_ARM1136 &&
497 	    ((id >> 20) & 3) == 0) {
498 		elf_hwcap &= ~HWCAP_TLS;
499 		return;
500 	}
501 
502 	/* Verify if CPUID scheme is implemented */
503 	if ((id & 0x000f0000) != 0x000f0000)
504 		return;
505 
506 	/*
507 	 * If the CPU supports LDREX/STREX and LDREXB/STREXB,
508 	 * avoid advertising SWP; it may not be atomic with
509 	 * multiprocessing cores.
510 	 */
511 	if (cpuid_feature_extract(CPUID_EXT_ISAR3, 12) > 1 ||
512 	    (cpuid_feature_extract(CPUID_EXT_ISAR3, 12) == 1 &&
513 	     cpuid_feature_extract(CPUID_EXT_ISAR4, 20) >= 3))
514 		elf_hwcap &= ~HWCAP_SWP;
515 }
516 
517 /*
518  * cpu_init - initialise one CPU.
519  *
520  * cpu_init sets up the per-CPU stacks.
521  */
522 void notrace cpu_init(void)
523 {
524 #ifndef CONFIG_CPU_V7M
525 	unsigned int cpu = smp_processor_id();
526 	struct stack *stk = &stacks[cpu];
527 
528 	if (cpu >= NR_CPUS) {
529 		pr_crit("CPU%u: bad primary CPU number\n", cpu);
530 		BUG();
531 	}
532 
533 	/*
534 	 * This only works on resume and secondary cores. For booting on the
535 	 * boot cpu, smp_prepare_boot_cpu is called after percpu area setup.
536 	 */
537 	set_my_cpu_offset(per_cpu_offset(cpu));
538 
539 	cpu_proc_init();
540 
541 	/*
542 	 * Define the placement constraint for the inline asm directive below.
543 	 * In Thumb-2, msr with an immediate value is not allowed.
544 	 */
545 #ifdef CONFIG_THUMB2_KERNEL
546 #define PLC	"r"
547 #else
548 #define PLC	"I"
549 #endif
550 
551 	/*
552 	 * setup stacks for re-entrant exception handlers
553 	 */
554 	__asm__ (
555 	"msr	cpsr_c, %1\n\t"
556 	"add	r14, %0, %2\n\t"
557 	"mov	sp, r14\n\t"
558 	"msr	cpsr_c, %3\n\t"
559 	"add	r14, %0, %4\n\t"
560 	"mov	sp, r14\n\t"
561 	"msr	cpsr_c, %5\n\t"
562 	"add	r14, %0, %6\n\t"
563 	"mov	sp, r14\n\t"
564 	"msr	cpsr_c, %7\n\t"
565 	"add	r14, %0, %8\n\t"
566 	"mov	sp, r14\n\t"
567 	"msr	cpsr_c, %9"
568 	    :
569 	    : "r" (stk),
570 	      PLC (PSR_F_BIT | PSR_I_BIT | IRQ_MODE),
571 	      "I" (offsetof(struct stack, irq[0])),
572 	      PLC (PSR_F_BIT | PSR_I_BIT | ABT_MODE),
573 	      "I" (offsetof(struct stack, abt[0])),
574 	      PLC (PSR_F_BIT | PSR_I_BIT | UND_MODE),
575 	      "I" (offsetof(struct stack, und[0])),
576 	      PLC (PSR_F_BIT | PSR_I_BIT | FIQ_MODE),
577 	      "I" (offsetof(struct stack, fiq[0])),
578 	      PLC (PSR_F_BIT | PSR_I_BIT | SVC_MODE)
579 	    : "r14");
580 #endif
581 }
582 
583 u32 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = MPIDR_INVALID };
584 
585 void __init smp_setup_processor_id(void)
586 {
587 	int i;
588 	u32 mpidr = is_smp() ? read_cpuid_mpidr() & MPIDR_HWID_BITMASK : 0;
589 	u32 cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
590 
591 	cpu_logical_map(0) = cpu;
592 	for (i = 1; i < nr_cpu_ids; ++i)
593 		cpu_logical_map(i) = i == cpu ? 0 : i;
594 
595 	/*
596 	 * clear __my_cpu_offset on boot CPU to avoid hang caused by
597 	 * using percpu variable early, for example, lockdep will
598 	 * access percpu variable inside lock_release
599 	 */
600 	set_my_cpu_offset(0);
601 
602 	pr_info("Booting Linux on physical CPU 0x%x\n", mpidr);
603 }
604 
605 struct mpidr_hash mpidr_hash;
606 #ifdef CONFIG_SMP
607 /**
608  * smp_build_mpidr_hash - Pre-compute shifts required at each affinity
609  *			  level in order to build a linear index from an
610  *			  MPIDR value. Resulting algorithm is a collision
611  *			  free hash carried out through shifting and ORing
612  */
613 static void __init smp_build_mpidr_hash(void)
614 {
615 	u32 i, affinity;
616 	u32 fs[3], bits[3], ls, mask = 0;
617 	/*
618 	 * Pre-scan the list of MPIDRS and filter out bits that do
619 	 * not contribute to affinity levels, ie they never toggle.
620 	 */
621 	for_each_possible_cpu(i)
622 		mask |= (cpu_logical_map(i) ^ cpu_logical_map(0));
623 	pr_debug("mask of set bits 0x%x\n", mask);
624 	/*
625 	 * Find and stash the last and first bit set at all affinity levels to
626 	 * check how many bits are required to represent them.
627 	 */
628 	for (i = 0; i < 3; i++) {
629 		affinity = MPIDR_AFFINITY_LEVEL(mask, i);
630 		/*
631 		 * Find the MSB bit and LSB bits position
632 		 * to determine how many bits are required
633 		 * to express the affinity level.
634 		 */
635 		ls = fls(affinity);
636 		fs[i] = affinity ? ffs(affinity) - 1 : 0;
637 		bits[i] = ls - fs[i];
638 	}
639 	/*
640 	 * An index can be created from the MPIDR by isolating the
641 	 * significant bits at each affinity level and by shifting
642 	 * them in order to compress the 24 bits values space to a
643 	 * compressed set of values. This is equivalent to hashing
644 	 * the MPIDR through shifting and ORing. It is a collision free
645 	 * hash though not minimal since some levels might contain a number
646 	 * of CPUs that is not an exact power of 2 and their bit
647 	 * representation might contain holes, eg MPIDR[7:0] = {0x2, 0x80}.
648 	 */
649 	mpidr_hash.shift_aff[0] = fs[0];
650 	mpidr_hash.shift_aff[1] = MPIDR_LEVEL_BITS + fs[1] - bits[0];
651 	mpidr_hash.shift_aff[2] = 2*MPIDR_LEVEL_BITS + fs[2] -
652 						(bits[1] + bits[0]);
653 	mpidr_hash.mask = mask;
654 	mpidr_hash.bits = bits[2] + bits[1] + bits[0];
655 	pr_debug("MPIDR hash: aff0[%u] aff1[%u] aff2[%u] mask[0x%x] bits[%u]\n",
656 				mpidr_hash.shift_aff[0],
657 				mpidr_hash.shift_aff[1],
658 				mpidr_hash.shift_aff[2],
659 				mpidr_hash.mask,
660 				mpidr_hash.bits);
661 	/*
662 	 * 4x is an arbitrary value used to warn on a hash table much bigger
663 	 * than expected on most systems.
664 	 */
665 	if (mpidr_hash_size() > 4 * num_possible_cpus())
666 		pr_warn("Large number of MPIDR hash buckets detected\n");
667 	sync_cache_w(&mpidr_hash);
668 }
669 #endif
670 
671 /*
672  * locate processor in the list of supported processor types.  The linker
673  * builds this table for us from the entries in arch/arm/mm/proc-*.S
674  */
675 struct proc_info_list *lookup_processor(u32 midr)
676 {
677 	struct proc_info_list *list = lookup_processor_type(midr);
678 
679 	if (!list) {
680 		pr_err("CPU%u: configuration botched (ID %08x), CPU halted\n",
681 		       smp_processor_id(), midr);
682 		while (1)
683 		/* can't use cpu_relax() here as it may require MMU setup */;
684 	}
685 
686 	return list;
687 }
688 
689 static void __init setup_processor(void)
690 {
691 	unsigned int midr = read_cpuid_id();
692 	struct proc_info_list *list = lookup_processor(midr);
693 
694 	cpu_name = list->cpu_name;
695 	__cpu_architecture = __get_cpu_architecture();
696 
697 	init_proc_vtable(list->proc);
698 #ifdef MULTI_TLB
699 	cpu_tlb = *list->tlb;
700 #endif
701 #ifdef MULTI_USER
702 	cpu_user = *list->user;
703 #endif
704 #ifdef MULTI_CACHE
705 	cpu_cache = *list->cache;
706 #endif
707 
708 	pr_info("CPU: %s [%08x] revision %d (ARMv%s), cr=%08lx\n",
709 		list->cpu_name, midr, midr & 15,
710 		proc_arch[cpu_architecture()], get_cr());
711 
712 	snprintf(init_utsname()->machine, __NEW_UTS_LEN + 1, "%s%c",
713 		 list->arch_name, ENDIANNESS);
714 	snprintf(elf_platform, ELF_PLATFORM_SIZE, "%s%c",
715 		 list->elf_name, ENDIANNESS);
716 	elf_hwcap = list->elf_hwcap;
717 
718 	cpuid_init_hwcaps();
719 	patch_aeabi_idiv();
720 
721 #ifndef CONFIG_ARM_THUMB
722 	elf_hwcap &= ~(HWCAP_THUMB | HWCAP_IDIVT);
723 #endif
724 #ifdef CONFIG_MMU
725 	init_default_cache_policy(list->__cpu_mm_mmu_flags);
726 #endif
727 	erratum_a15_798181_init();
728 
729 	elf_hwcap_fixup();
730 
731 	cacheid_init();
732 	cpu_init();
733 }
734 
735 void __init dump_machine_table(void)
736 {
737 	const struct machine_desc *p;
738 
739 	early_print("Available machine support:\n\nID (hex)\tNAME\n");
740 	for_each_machine_desc(p)
741 		early_print("%08x\t%s\n", p->nr, p->name);
742 
743 	early_print("\nPlease check your kernel config and/or bootloader.\n");
744 
745 	while (true)
746 		/* can't use cpu_relax() here as it may require MMU setup */;
747 }
748 
749 int __init arm_add_memory(u64 start, u64 size)
750 {
751 	u64 aligned_start;
752 
753 	/*
754 	 * Ensure that start/size are aligned to a page boundary.
755 	 * Size is rounded down, start is rounded up.
756 	 */
757 	aligned_start = PAGE_ALIGN(start);
758 	if (aligned_start > start + size)
759 		size = 0;
760 	else
761 		size -= aligned_start - start;
762 
763 #ifndef CONFIG_PHYS_ADDR_T_64BIT
764 	if (aligned_start > ULONG_MAX) {
765 		pr_crit("Ignoring memory at 0x%08llx outside 32-bit physical address space\n",
766 			(long long)start);
767 		return -EINVAL;
768 	}
769 
770 	if (aligned_start + size > ULONG_MAX) {
771 		pr_crit("Truncating memory at 0x%08llx to fit in 32-bit physical address space\n",
772 			(long long)start);
773 		/*
774 		 * To ensure bank->start + bank->size is representable in
775 		 * 32 bits, we use ULONG_MAX as the upper limit rather than 4GB.
776 		 * This means we lose a page after masking.
777 		 */
778 		size = ULONG_MAX - aligned_start;
779 	}
780 #endif
781 
782 	if (aligned_start < PHYS_OFFSET) {
783 		if (aligned_start + size <= PHYS_OFFSET) {
784 			pr_info("Ignoring memory below PHYS_OFFSET: 0x%08llx-0x%08llx\n",
785 				aligned_start, aligned_start + size);
786 			return -EINVAL;
787 		}
788 
789 		pr_info("Ignoring memory below PHYS_OFFSET: 0x%08llx-0x%08llx\n",
790 			aligned_start, (u64)PHYS_OFFSET);
791 
792 		size -= PHYS_OFFSET - aligned_start;
793 		aligned_start = PHYS_OFFSET;
794 	}
795 
796 	start = aligned_start;
797 	size = size & ~(phys_addr_t)(PAGE_SIZE - 1);
798 
799 	/*
800 	 * Check whether this memory region has non-zero size or
801 	 * invalid node number.
802 	 */
803 	if (size == 0)
804 		return -EINVAL;
805 
806 	memblock_add(start, size);
807 	return 0;
808 }
809 
810 /*
811  * Pick out the memory size.  We look for mem=size@start,
812  * where start and size are "size[KkMm]"
813  */
814 
815 static int __init early_mem(char *p)
816 {
817 	static int usermem __initdata = 0;
818 	u64 size;
819 	u64 start;
820 	char *endp;
821 
822 	/*
823 	 * If the user specifies memory size, we
824 	 * blow away any automatically generated
825 	 * size.
826 	 */
827 	if (usermem == 0) {
828 		usermem = 1;
829 		memblock_remove(memblock_start_of_DRAM(),
830 			memblock_end_of_DRAM() - memblock_start_of_DRAM());
831 	}
832 
833 	start = PHYS_OFFSET;
834 	size  = memparse(p, &endp);
835 	if (*endp == '@')
836 		start = memparse(endp + 1, NULL);
837 
838 	arm_add_memory(start, size);
839 
840 	return 0;
841 }
842 early_param("mem", early_mem);
843 
844 static void __init request_standard_resources(const struct machine_desc *mdesc)
845 {
846 	struct memblock_region *region;
847 	struct resource *res;
848 
849 	kernel_code.start   = virt_to_phys(_text);
850 	kernel_code.end     = virt_to_phys(__init_begin - 1);
851 	kernel_data.start   = virt_to_phys(_sdata);
852 	kernel_data.end     = virt_to_phys(_end - 1);
853 
854 	for_each_memblock(memory, region) {
855 		phys_addr_t start = __pfn_to_phys(memblock_region_memory_base_pfn(region));
856 		phys_addr_t end = __pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1;
857 		unsigned long boot_alias_start;
858 
859 		/*
860 		 * Some systems have a special memory alias which is only
861 		 * used for booting.  We need to advertise this region to
862 		 * kexec-tools so they know where bootable RAM is located.
863 		 */
864 		boot_alias_start = phys_to_idmap(start);
865 		if (arm_has_idmap_alias() && boot_alias_start != IDMAP_INVALID_ADDR) {
866 			res = memblock_alloc(sizeof(*res), SMP_CACHE_BYTES);
867 			if (!res)
868 				panic("%s: Failed to allocate %zu bytes\n",
869 				      __func__, sizeof(*res));
870 			res->name = "System RAM (boot alias)";
871 			res->start = boot_alias_start;
872 			res->end = phys_to_idmap(end);
873 			res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
874 			request_resource(&iomem_resource, res);
875 		}
876 
877 		res = memblock_alloc(sizeof(*res), SMP_CACHE_BYTES);
878 		if (!res)
879 			panic("%s: Failed to allocate %zu bytes\n", __func__,
880 			      sizeof(*res));
881 		res->name  = "System RAM";
882 		res->start = start;
883 		res->end = end;
884 		res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
885 
886 		request_resource(&iomem_resource, res);
887 
888 		if (kernel_code.start >= res->start &&
889 		    kernel_code.end <= res->end)
890 			request_resource(res, &kernel_code);
891 		if (kernel_data.start >= res->start &&
892 		    kernel_data.end <= res->end)
893 			request_resource(res, &kernel_data);
894 	}
895 
896 	if (mdesc->video_start) {
897 		video_ram.start = mdesc->video_start;
898 		video_ram.end   = mdesc->video_end;
899 		request_resource(&iomem_resource, &video_ram);
900 	}
901 
902 	/*
903 	 * Some machines don't have the possibility of ever
904 	 * possessing lp0, lp1 or lp2
905 	 */
906 	if (mdesc->reserve_lp0)
907 		request_resource(&ioport_resource, &lp0);
908 	if (mdesc->reserve_lp1)
909 		request_resource(&ioport_resource, &lp1);
910 	if (mdesc->reserve_lp2)
911 		request_resource(&ioport_resource, &lp2);
912 }
913 
914 #if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_DUMMY_CONSOLE) || \
915     defined(CONFIG_EFI)
916 struct screen_info screen_info = {
917  .orig_video_lines	= 30,
918  .orig_video_cols	= 80,
919  .orig_video_mode	= 0,
920  .orig_video_ega_bx	= 0,
921  .orig_video_isVGA	= 1,
922  .orig_video_points	= 8
923 };
924 #endif
925 
926 static int __init customize_machine(void)
927 {
928 	/*
929 	 * customizes platform devices, or adds new ones
930 	 * On DT based machines, we fall back to populating the
931 	 * machine from the device tree, if no callback is provided,
932 	 * otherwise we would always need an init_machine callback.
933 	 */
934 	if (machine_desc->init_machine)
935 		machine_desc->init_machine();
936 
937 	return 0;
938 }
939 arch_initcall(customize_machine);
940 
941 static int __init init_machine_late(void)
942 {
943 	struct device_node *root;
944 	int ret;
945 
946 	if (machine_desc->init_late)
947 		machine_desc->init_late();
948 
949 	root = of_find_node_by_path("/");
950 	if (root) {
951 		ret = of_property_read_string(root, "serial-number",
952 					      &system_serial);
953 		if (ret)
954 			system_serial = NULL;
955 	}
956 
957 	if (!system_serial)
958 		system_serial = kasprintf(GFP_KERNEL, "%08x%08x",
959 					  system_serial_high,
960 					  system_serial_low);
961 
962 	return 0;
963 }
964 late_initcall(init_machine_late);
965 
966 #ifdef CONFIG_KEXEC
967 /*
968  * The crash region must be aligned to 128MB to avoid
969  * zImage relocating below the reserved region.
970  */
971 #define CRASH_ALIGN	(128 << 20)
972 
973 static inline unsigned long long get_total_mem(void)
974 {
975 	unsigned long total;
976 
977 	total = max_low_pfn - min_low_pfn;
978 	return total << PAGE_SHIFT;
979 }
980 
981 /**
982  * reserve_crashkernel() - reserves memory are for crash kernel
983  *
984  * This function reserves memory area given in "crashkernel=" kernel command
985  * line parameter. The memory reserved is used by a dump capture kernel when
986  * primary kernel is crashing.
987  */
988 static void __init reserve_crashkernel(void)
989 {
990 	unsigned long long crash_size, crash_base;
991 	unsigned long long total_mem;
992 	int ret;
993 
994 	total_mem = get_total_mem();
995 	ret = parse_crashkernel(boot_command_line, total_mem,
996 				&crash_size, &crash_base);
997 	if (ret)
998 		return;
999 
1000 	if (crash_base <= 0) {
1001 		unsigned long long crash_max = idmap_to_phys((u32)~0);
1002 		unsigned long long lowmem_max = __pa(high_memory - 1) + 1;
1003 		if (crash_max > lowmem_max)
1004 			crash_max = lowmem_max;
1005 		crash_base = memblock_find_in_range(CRASH_ALIGN, crash_max,
1006 						    crash_size, CRASH_ALIGN);
1007 		if (!crash_base) {
1008 			pr_err("crashkernel reservation failed - No suitable area found.\n");
1009 			return;
1010 		}
1011 	} else {
1012 		unsigned long long start;
1013 
1014 		start = memblock_find_in_range(crash_base,
1015 					       crash_base + crash_size,
1016 					       crash_size, SECTION_SIZE);
1017 		if (start != crash_base) {
1018 			pr_err("crashkernel reservation failed - memory is in use.\n");
1019 			return;
1020 		}
1021 	}
1022 
1023 	ret = memblock_reserve(crash_base, crash_size);
1024 	if (ret < 0) {
1025 		pr_warn("crashkernel reservation failed - memory is in use (0x%lx)\n",
1026 			(unsigned long)crash_base);
1027 		return;
1028 	}
1029 
1030 	pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
1031 		(unsigned long)(crash_size >> 20),
1032 		(unsigned long)(crash_base >> 20),
1033 		(unsigned long)(total_mem >> 20));
1034 
1035 	/* The crashk resource must always be located in normal mem */
1036 	crashk_res.start = crash_base;
1037 	crashk_res.end = crash_base + crash_size - 1;
1038 	insert_resource(&iomem_resource, &crashk_res);
1039 
1040 	if (arm_has_idmap_alias()) {
1041 		/*
1042 		 * If we have a special RAM alias for use at boot, we
1043 		 * need to advertise to kexec tools where the alias is.
1044 		 */
1045 		static struct resource crashk_boot_res = {
1046 			.name = "Crash kernel (boot alias)",
1047 			.flags = IORESOURCE_BUSY | IORESOURCE_MEM,
1048 		};
1049 
1050 		crashk_boot_res.start = phys_to_idmap(crash_base);
1051 		crashk_boot_res.end = crashk_boot_res.start + crash_size - 1;
1052 		insert_resource(&iomem_resource, &crashk_boot_res);
1053 	}
1054 }
1055 #else
1056 static inline void reserve_crashkernel(void) {}
1057 #endif /* CONFIG_KEXEC */
1058 
1059 void __init hyp_mode_check(void)
1060 {
1061 #ifdef CONFIG_ARM_VIRT_EXT
1062 	sync_boot_mode();
1063 
1064 	if (is_hyp_mode_available()) {
1065 		pr_info("CPU: All CPU(s) started in HYP mode.\n");
1066 		pr_info("CPU: Virtualization extensions available.\n");
1067 	} else if (is_hyp_mode_mismatched()) {
1068 		pr_warn("CPU: WARNING: CPU(s) started in wrong/inconsistent modes (primary CPU mode 0x%x)\n",
1069 			__boot_cpu_mode & MODE_MASK);
1070 		pr_warn("CPU: This may indicate a broken bootloader or firmware.\n");
1071 	} else
1072 		pr_info("CPU: All CPU(s) started in SVC mode.\n");
1073 #endif
1074 }
1075 
1076 void __init setup_arch(char **cmdline_p)
1077 {
1078 	const struct machine_desc *mdesc;
1079 
1080 	setup_processor();
1081 	mdesc = setup_machine_fdt(__atags_pointer);
1082 	if (!mdesc)
1083 		mdesc = setup_machine_tags(__atags_pointer, __machine_arch_type);
1084 	if (!mdesc) {
1085 		early_print("\nError: invalid dtb and unrecognized/unsupported machine ID\n");
1086 		early_print("  r1=0x%08x, r2=0x%08x\n", __machine_arch_type,
1087 			    __atags_pointer);
1088 		if (__atags_pointer)
1089 			early_print("  r2[]=%*ph\n", 16,
1090 				    phys_to_virt(__atags_pointer));
1091 		dump_machine_table();
1092 	}
1093 
1094 	machine_desc = mdesc;
1095 	machine_name = mdesc->name;
1096 	dump_stack_set_arch_desc("%s", mdesc->name);
1097 
1098 	if (mdesc->reboot_mode != REBOOT_HARD)
1099 		reboot_mode = mdesc->reboot_mode;
1100 
1101 	init_mm.start_code = (unsigned long) _text;
1102 	init_mm.end_code   = (unsigned long) _etext;
1103 	init_mm.end_data   = (unsigned long) _edata;
1104 	init_mm.brk	   = (unsigned long) _end;
1105 
1106 	/* populate cmd_line too for later use, preserving boot_command_line */
1107 	strlcpy(cmd_line, boot_command_line, COMMAND_LINE_SIZE);
1108 	*cmdline_p = cmd_line;
1109 
1110 	early_fixmap_init();
1111 	early_ioremap_init();
1112 
1113 	parse_early_param();
1114 
1115 #ifdef CONFIG_MMU
1116 	early_mm_init(mdesc);
1117 #endif
1118 	setup_dma_zone(mdesc);
1119 	xen_early_init();
1120 	efi_init();
1121 	/*
1122 	 * Make sure the calculation for lowmem/highmem is set appropriately
1123 	 * before reserving/allocating any mmeory
1124 	 */
1125 	adjust_lowmem_bounds();
1126 	arm_memblock_init(mdesc);
1127 	/* Memory may have been removed so recalculate the bounds. */
1128 	adjust_lowmem_bounds();
1129 
1130 	early_ioremap_reset();
1131 
1132 	paging_init(mdesc);
1133 	request_standard_resources(mdesc);
1134 
1135 	if (mdesc->restart)
1136 		arm_pm_restart = mdesc->restart;
1137 
1138 	unflatten_device_tree();
1139 
1140 	arm_dt_init_cpu_maps();
1141 	psci_dt_init();
1142 #ifdef CONFIG_SMP
1143 	if (is_smp()) {
1144 		if (!mdesc->smp_init || !mdesc->smp_init()) {
1145 			if (psci_smp_available())
1146 				smp_set_ops(&psci_smp_ops);
1147 			else if (mdesc->smp)
1148 				smp_set_ops(mdesc->smp);
1149 		}
1150 		smp_init_cpus();
1151 		smp_build_mpidr_hash();
1152 	}
1153 #endif
1154 
1155 	if (!is_smp())
1156 		hyp_mode_check();
1157 
1158 	reserve_crashkernel();
1159 
1160 #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
1161 	handle_arch_irq = mdesc->handle_irq;
1162 #endif
1163 
1164 #ifdef CONFIG_VT
1165 #if defined(CONFIG_VGA_CONSOLE)
1166 	conswitchp = &vga_con;
1167 #elif defined(CONFIG_DUMMY_CONSOLE)
1168 	conswitchp = &dummy_con;
1169 #endif
1170 #endif
1171 
1172 	if (mdesc->init_early)
1173 		mdesc->init_early();
1174 }
1175 
1176 
1177 static int __init topology_init(void)
1178 {
1179 	int cpu;
1180 
1181 	for_each_possible_cpu(cpu) {
1182 		struct cpuinfo_arm *cpuinfo = &per_cpu(cpu_data, cpu);
1183 		cpuinfo->cpu.hotpluggable = platform_can_hotplug_cpu(cpu);
1184 		register_cpu(&cpuinfo->cpu, cpu);
1185 	}
1186 
1187 	return 0;
1188 }
1189 subsys_initcall(topology_init);
1190 
1191 #ifdef CONFIG_HAVE_PROC_CPU
1192 static int __init proc_cpu_init(void)
1193 {
1194 	struct proc_dir_entry *res;
1195 
1196 	res = proc_mkdir("cpu", NULL);
1197 	if (!res)
1198 		return -ENOMEM;
1199 	return 0;
1200 }
1201 fs_initcall(proc_cpu_init);
1202 #endif
1203 
1204 static const char *hwcap_str[] = {
1205 	"swp",
1206 	"half",
1207 	"thumb",
1208 	"26bit",
1209 	"fastmult",
1210 	"fpa",
1211 	"vfp",
1212 	"edsp",
1213 	"java",
1214 	"iwmmxt",
1215 	"crunch",
1216 	"thumbee",
1217 	"neon",
1218 	"vfpv3",
1219 	"vfpv3d16",
1220 	"tls",
1221 	"vfpv4",
1222 	"idiva",
1223 	"idivt",
1224 	"vfpd32",
1225 	"lpae",
1226 	"evtstrm",
1227 	NULL
1228 };
1229 
1230 static const char *hwcap2_str[] = {
1231 	"aes",
1232 	"pmull",
1233 	"sha1",
1234 	"sha2",
1235 	"crc32",
1236 	NULL
1237 };
1238 
1239 static int c_show(struct seq_file *m, void *v)
1240 {
1241 	int i, j;
1242 	u32 cpuid;
1243 
1244 	for_each_online_cpu(i) {
1245 		/*
1246 		 * glibc reads /proc/cpuinfo to determine the number of
1247 		 * online processors, looking for lines beginning with
1248 		 * "processor".  Give glibc what it expects.
1249 		 */
1250 		seq_printf(m, "processor\t: %d\n", i);
1251 		cpuid = is_smp() ? per_cpu(cpu_data, i).cpuid : read_cpuid_id();
1252 		seq_printf(m, "model name\t: %s rev %d (%s)\n",
1253 			   cpu_name, cpuid & 15, elf_platform);
1254 
1255 #if defined(CONFIG_SMP)
1256 		seq_printf(m, "BogoMIPS\t: %lu.%02lu\n",
1257 			   per_cpu(cpu_data, i).loops_per_jiffy / (500000UL/HZ),
1258 			   (per_cpu(cpu_data, i).loops_per_jiffy / (5000UL/HZ)) % 100);
1259 #else
1260 		seq_printf(m, "BogoMIPS\t: %lu.%02lu\n",
1261 			   loops_per_jiffy / (500000/HZ),
1262 			   (loops_per_jiffy / (5000/HZ)) % 100);
1263 #endif
1264 		/* dump out the processor features */
1265 		seq_puts(m, "Features\t: ");
1266 
1267 		for (j = 0; hwcap_str[j]; j++)
1268 			if (elf_hwcap & (1 << j))
1269 				seq_printf(m, "%s ", hwcap_str[j]);
1270 
1271 		for (j = 0; hwcap2_str[j]; j++)
1272 			if (elf_hwcap2 & (1 << j))
1273 				seq_printf(m, "%s ", hwcap2_str[j]);
1274 
1275 		seq_printf(m, "\nCPU implementer\t: 0x%02x\n", cpuid >> 24);
1276 		seq_printf(m, "CPU architecture: %s\n",
1277 			   proc_arch[cpu_architecture()]);
1278 
1279 		if ((cpuid & 0x0008f000) == 0x00000000) {
1280 			/* pre-ARM7 */
1281 			seq_printf(m, "CPU part\t: %07x\n", cpuid >> 4);
1282 		} else {
1283 			if ((cpuid & 0x0008f000) == 0x00007000) {
1284 				/* ARM7 */
1285 				seq_printf(m, "CPU variant\t: 0x%02x\n",
1286 					   (cpuid >> 16) & 127);
1287 			} else {
1288 				/* post-ARM7 */
1289 				seq_printf(m, "CPU variant\t: 0x%x\n",
1290 					   (cpuid >> 20) & 15);
1291 			}
1292 			seq_printf(m, "CPU part\t: 0x%03x\n",
1293 				   (cpuid >> 4) & 0xfff);
1294 		}
1295 		seq_printf(m, "CPU revision\t: %d\n\n", cpuid & 15);
1296 	}
1297 
1298 	seq_printf(m, "Hardware\t: %s\n", machine_name);
1299 	seq_printf(m, "Revision\t: %04x\n", system_rev);
1300 	seq_printf(m, "Serial\t\t: %s\n", system_serial);
1301 
1302 	return 0;
1303 }
1304 
1305 static void *c_start(struct seq_file *m, loff_t *pos)
1306 {
1307 	return *pos < 1 ? (void *)1 : NULL;
1308 }
1309 
1310 static void *c_next(struct seq_file *m, void *v, loff_t *pos)
1311 {
1312 	++*pos;
1313 	return NULL;
1314 }
1315 
1316 static void c_stop(struct seq_file *m, void *v)
1317 {
1318 }
1319 
1320 const struct seq_operations cpuinfo_op = {
1321 	.start	= c_start,
1322 	.next	= c_next,
1323 	.stop	= c_stop,
1324 	.show	= c_show
1325 };
1326