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kernel/linux-imx6_3.14.28/arch/mips/sgi-ip22/ip22-nvram.c 3.56 KB
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  /*
   * ip22-nvram.c: NVRAM and serial EEPROM handling.
   *
   * Copyright (C) 2003 Ladislav Michl (ladis@linux-mips.org)
   */
  #include <linux/module.h>
  
  #include <asm/sgi/hpc3.h>
  #include <asm/sgi/ip22.h>
  
  /* Control opcode for serial eeprom  */
  #define EEPROM_READ	0xc000	/* serial memory read */
  #define EEPROM_WEN	0x9800	/* write enable before prog modes */
  #define EEPROM_WRITE	0xa000	/* serial memory write */
  #define EEPROM_WRALL	0x8800	/* write all registers */
  #define EEPROM_WDS	0x8000	/* disable all programming */
  #define EEPROM_PRREAD	0xc000	/* read protect register */
  #define EEPROM_PREN	0x9800	/* enable protect register mode */
  #define EEPROM_PRCLEAR	0xffff	/* clear protect register */
  #define EEPROM_PRWRITE	0xa000	/* write protect register */
  #define EEPROM_PRDS	0x8000	/* disable protect register, forever */
  
  #define EEPROM_EPROT	0x01	/* Protect register enable */
  #define EEPROM_CSEL	0x02	/* Chip select */
  #define EEPROM_ECLK	0x04	/* EEPROM clock */
  #define EEPROM_DATO	0x08	/* Data out */
  #define EEPROM_DATI	0x10	/* Data in */
  
  /* We need to use these functions early... */
  #define delay() ({						\
  	int x;							\
  	for (x=0; x<100000; x++) __asm__ __volatile__(""); })
  
  #define eeprom_cs_on(ptr) ({	\
  	__raw_writel(__raw_readl(ptr) & ~EEPROM_DATO, ptr);	\
  	__raw_writel(__raw_readl(ptr) & ~EEPROM_ECLK, ptr);	\
  	__raw_writel(__raw_readl(ptr) & ~EEPROM_EPROT, ptr);	\
  	delay();						\
  	__raw_writel(__raw_readl(ptr) | EEPROM_CSEL, ptr);	\
  	__raw_writel(__raw_readl(ptr) | EEPROM_ECLK, ptr); })
  
  
  #define eeprom_cs_off(ptr) ({	\
  	__raw_writel(__raw_readl(ptr) & ~EEPROM_ECLK, ptr);	\
  	__raw_writel(__raw_readl(ptr) & ~EEPROM_CSEL, ptr);	\
  	__raw_writel(__raw_readl(ptr) | EEPROM_EPROT, ptr);	\
  	__raw_writel(__raw_readl(ptr) | EEPROM_ECLK, ptr); })
  
  #define BITS_IN_COMMAND 11
  /*
   * clock in the nvram command and the register number. For the
   * national semiconductor nv ram chip the op code is 3 bits and
   * the address is 6/8 bits.
   */
  static inline void eeprom_cmd(unsigned int *ctrl, unsigned cmd, unsigned reg)
  {
  	unsigned short ser_cmd;
  	int i;
  
  	ser_cmd = cmd | (reg << (16 - BITS_IN_COMMAND));
  	for (i = 0; i < BITS_IN_COMMAND; i++) {
  		if (ser_cmd & (1<<15))	/* if high order bit set */
  			__raw_writel(__raw_readl(ctrl) | EEPROM_DATO, ctrl);
  		else
  			__raw_writel(__raw_readl(ctrl) & ~EEPROM_DATO, ctrl);
  		__raw_writel(__raw_readl(ctrl) & ~EEPROM_ECLK, ctrl);
  		delay();
  		__raw_writel(__raw_readl(ctrl) | EEPROM_ECLK, ctrl);
  		delay();
  		ser_cmd <<= 1;
  	}
  	/* see data sheet timing diagram */
  	__raw_writel(__raw_readl(ctrl) & ~EEPROM_DATO, ctrl);
  }
  
  unsigned short ip22_eeprom_read(unsigned int *ctrl, int reg)
  {
  	unsigned short res = 0;
  	int i;
  
  	__raw_writel(__raw_readl(ctrl) & ~EEPROM_EPROT, ctrl);
  	eeprom_cs_on(ctrl);
  	eeprom_cmd(ctrl, EEPROM_READ, reg);
  
  	/* clock the data ouf of serial mem */
  	for (i = 0; i < 16; i++) {
  		__raw_writel(__raw_readl(ctrl) & ~EEPROM_ECLK, ctrl);
  		delay();
  		__raw_writel(__raw_readl(ctrl) | EEPROM_ECLK, ctrl);
  		delay();
  		res <<= 1;
  		if (__raw_readl(ctrl) & EEPROM_DATI)
  			res |= 1;
  	}
  
  	eeprom_cs_off(ctrl);
  
  	return res;
  }
  
  EXPORT_SYMBOL(ip22_eeprom_read);
  
  /*
   * Read specified register from main NVRAM
   */
  unsigned short ip22_nvram_read(int reg)
  {
  	if (ip22_is_fullhouse())
  		/* IP22 (Indigo2 aka FullHouse) stores env variables into
  		 * 93CS56 Microwire Bus EEPROM 2048 Bit (128x16) */
  		return ip22_eeprom_read(&hpc3c0->eeprom, reg);
  	else {
  		unsigned short tmp;
  		/* IP24 (Indy aka Guiness) uses DS1386 8K version */
  		reg <<= 1;
  		tmp = hpc3c0->bbram[reg++] & 0xff;
  		return (tmp << 8) | (hpc3c0->bbram[reg] & 0xff);
  	}
  }
  
  EXPORT_SYMBOL(ip22_nvram_read);