text: // SPDX-License-Identifier: GPL-2.0
  /*
   *    Copyright IBM Corp. 2016
   */
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <asm/processor.h>
  #include <asm/facility.h>
  #include <asm/lowcore.h>
  #include <asm/sclp.h>
  #include "entry.h"
  
  /*
   * The code within this file will be called very early. It may _not_
   * access anything within the bss section, since that is not cleared
   * yet and may contain data (e.g. initrd) that must be saved by other
   * code.
   * For temporary objects the stack (16k) should be used.
   */
  
  static unsigned long als[] __initdata = { FACILITIES_ALS };
  
  static void __init u16_to_hex(char *str, u16 val)
  {
  	int i, num;
  
  	for (i = 1; i <= 4; i++) {
  		num = (val >> (16 - 4 * i)) & 0xf;
  		if (num >= 10)
  			num += 7;
  		*str++ = '0' + num;
  	}
  	*str = '\0';
  }
  
  static void __init print_machine_type(void)
  {
  	static char mach_str[80] __initdata = "Detected machine-type number: ";
  	char type_str[5];
  	struct cpuid id;
  
  	get_cpu_id(&id);
  	u16_to_hex(type_str, id.machine);
  	strcat(mach_str, type_str);
  	strcat(mach_str, "\n");
  	sclp_early_printk(mach_str);
  }
  
  static void __init u16_to_decimal(char *str, u16 val)
  {
  	int div = 1;
  
  	while (div * 10 <= val)
  		div *= 10;
  	while (div) {
  		*str++ = '0' + val / div;
  		val %= div;
  		div /= 10;
  	}
  	*str = '\0';
  }
  
  static void __init print_missing_facilities(void)
  {
  	static char als_str[80] __initdata = "Missing facilities: ";
  	unsigned long val;
  	char val_str[6];
  	int i, j, first;
  
  	first = 1;
  	for (i = 0; i < ARRAY_SIZE(als); i++) {
  		val = ~S390_lowcore.stfle_fac_list[i] & als[i];
  		for (j = 0; j < BITS_PER_LONG; j++) {
  			if (!(val & (1UL << (BITS_PER_LONG - 1 - j))))
  				continue;
  			if (!first)
  				strcat(als_str, ",");
  			/*
  			 * Make sure we stay within one line. Consider that
  			 * each facility bit adds up to five characters and
  			 * z/VM adds a four character prefix.
  			 */
  			if (strlen(als_str) > 70) {
  				strcat(als_str, "\n");
  				sclp_early_printk(als_str);
  				*als_str = '\0';
  			}
  			u16_to_decimal(val_str, i * BITS_PER_LONG + j);
  			strcat(als_str, val_str);
  			first = 0;
  		}
  	}
  	strcat(als_str, "\n");
  	sclp_early_printk(als_str);
  	sclp_early_printk("See Principles of Operations for facility bits\n");
  }
  
  static void __init facility_mismatch(void)
  {
  	sclp_early_printk("The Linux kernel requires more recent processor hardware\n");
  	print_machine_type();
  	print_missing_facilities();
  	disabled_wait(0x8badcccc);
  }
  
  void __init verify_facilities(void)
  {
  	int i;
  
  	for (i = 0; i < ARRAY_SIZE(S390_lowcore.stfle_fac_list); i++)
  		S390_lowcore.stfle_fac_list[i] = 0;
  	asm volatile(
  		"	stfl	0(0)\n"
  		: "=m" (S390_lowcore.stfl_fac_list));
  	S390_lowcore.stfle_fac_list[0] = (u64)S390_lowcore.stfl_fac_list << 32;
  	if (S390_lowcore.stfl_fac_list & 0x01000000) {
  		register unsigned long reg0 asm("0") = ARRAY_SIZE(als) - 1;
  
  		asm volatile(".insn s,0xb2b00000,0(%1)" /* stfle */
  			     : "+d" (reg0)
  			     : "a" (&S390_lowcore.stfle_fac_list)
  			     : "memory", "cc");
  	}
  	for (i = 0; i < ARRAY_SIZE(als); i++) {
  		if ((S390_lowcore.stfle_fac_list[i] & als[i]) != als[i])
  			facility_mismatch();
  	}
  }
  