include/linux/eeprom.h

/* credit winbond-840.c
 */
#include <asm/io.h>
struct eeprom_ops {
	void	(*set_cs)(void *ee);
	void	(*clear_cs)(void *ee);
};

#define EEPOL_EEDI	0x01
#define EEPOL_EEDO	0x02
#define EEPOL_EECLK	0x04
#define EEPOL_EESEL	0x08

struct eeprom {
	void *dev;
	struct eeprom_ops *ops;

	void __iomem *	addr;

	unsigned	ee_addr_bits;

	unsigned	eesel;
	unsigned	eeclk;
	unsigned	eedo;
	unsigned	eedi;
	unsigned	polarity;
	unsigned	ee_state;

	spinlock_t	*lock;
	u32		*cache;
};


u8   eeprom_readb(struct eeprom *ee, unsigned address);
void eeprom_read(struct eeprom *ee, unsigned address, u8 *bytes,
		unsigned count);
void eeprom_writeb(struct eeprom *ee, unsigned address, u8 data);
void eeprom_write(struct eeprom *ee, unsigned address, u8 *bytes,
		unsigned count);

/* The EEPROM commands include the alway-set leading bit. */
enum EEPROM_Cmds {
        EE_WriteCmd=(5 << 6), EE_ReadCmd=(6 << 6), EE_EraseCmd=(7 << 6),
};

void setup_ee_mem_bitbanger(struct eeprom *ee, void __iomem *memaddr, int eesel_bit, int eeclk_bit, int eedo_bit, int eedi_bit, unsigned polarity)
{
	ee->addr = memaddr;
	ee->eesel = 1 << eesel_bit;
	ee->eeclk = 1 << eeclk_bit;
	ee->eedo = 1 << eedo_bit;
	ee->eedi = 1 << eedi_bit;

	ee->polarity = polarity;

	*ee->cache = readl(ee->addr);
}

/* foo. put this in a .c file */
static inline void eeprom_update(struct eeprom *ee, u32 mask, int pol)
{
	unsigned long flags;
	u32 data;

	spin_lock_irqsave(ee->lock, flags);
	data = *ee->cache;

	data &= ~mask;
	if (pol)
		data |= mask;

	*ee->cache = data;
//printk("update: %08x\n", data);
	writel(data, ee->addr);
	spin_unlock_irqrestore(ee->lock, flags);
}

void eeprom_clk_lo(struct eeprom *ee)
{
	int pol = !!(ee->polarity & EEPOL_EECLK);

	eeprom_update(ee, ee->eeclk, pol);
	udelay(2);
}

void eeprom_clk_hi(struct eeprom *ee)
{
	int pol = !!(ee->polarity & EEPOL_EECLK);

	eeprom_update(ee, ee->eeclk, !pol);
	udelay(2);
}

void eeprom_send_addr(struct eeprom *ee, unsigned address)
{
	int pol = !!(ee->polarity & EEPOL_EEDI);
	unsigned i;
	address |= 6 << 6;

        /* Shift the read command bits out. */
        for (i=0; i<11; i++) {
		eeprom_update(ee, ee->eedi, ((address >> 10) & 1) ^ pol);
		address <<= 1;
		eeprom_clk_hi(ee);
		eeprom_clk_lo(ee);
        }
	eeprom_update(ee, ee->eedi, pol);
}

u16   eeprom_readw(struct eeprom *ee, unsigned address)
{
	unsigned i;
	u16	res = 0;

	eeprom_clk_lo(ee);
	eeprom_update(ee, ee->eesel, 1 ^ !!(ee->polarity & EEPOL_EESEL));
	eeprom_send_addr(ee, address);

	for (i=0; i<16; i++) {
		u32 data;
		eeprom_clk_hi(ee);
		res <<= 1;
		data = readl(ee->addr);
//printk("eeprom_readw: %08x\n", data);
		res |= !!(data & ee->eedo) ^ !!(ee->polarity & EEPOL_EEDO);
		eeprom_clk_lo(ee);
	}
	eeprom_update(ee, ee->eesel, 0 ^ !!(ee->polarity & EEPOL_EESEL));

	return res;
}


void eeprom_writeb(struct eeprom *ee, unsigned address, u8 data)
{
}