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/*
* Atmel AT93C46 serial eeprom driver
*
* Brian Murphy <brian.murphy@eicon.com>
*
*/
#include <linux/kernel.h>
#include <linux/delay.h>
#include <asm/lasat/lasat.h>
#include <linux/module.h>
#include <linux/init.h>
#include "at93c.h"
#define AT93C_ADDR_SHIFT 7
#define AT93C_ADDR_MAX ((1 << AT93C_ADDR_SHIFT) - 1)
#define AT93C_RCMD (0x6 << AT93C_ADDR_SHIFT)
#define AT93C_WCMD (0x5 << AT93C_ADDR_SHIFT)
#define AT93C_WENCMD 0x260
#define AT93C_WDSCMD 0x200
struct at93c_defs *at93c;
static void at93c_reg_write(u32 val)
{
*at93c->reg = val;
}
static u32 at93c_reg_read(void)
{
u32 tmp = *at93c->reg;
return tmp;
}
static u32 at93c_datareg_read(void)
{
u32 tmp = *at93c->rdata_reg;
return tmp;
}
static void at93c_cycle_clk(u32 data)
{
at93c_reg_write(data | at93c->clk);
lasat_ndelay(250);
at93c_reg_write(data & ~at93c->clk);
lasat_ndelay(250);
}
static void at93c_write_databit(u8 bit)
{
u32 data = at93c_reg_read();
if (bit)
data |= 1 << at93c->wdata_shift;
else
data &= ~(1 << at93c->wdata_shift);
at93c_reg_write(data);
lasat_ndelay(100);
at93c_cycle_clk(data);
}
static unsigned int at93c_read_databit(void)
{
u32 data;
at93c_cycle_clk(at93c_reg_read());
data = (at93c_datareg_read() >> at93c->rdata_shift) & 1;
return data;
}
static u8 at93c_read_byte(void)
{
int i;
u8 data = 0;
for (i = 0; i<=7; i++) {
data <<= 1;
data |= at93c_read_databit();
}
return data;
}
static void at93c_write_bits(u32 data, int size)
{
int i;
int shift = size - 1;
u32 mask = (1 << shift);
for (i = 0; i < size; i++) {
at93c_write_databit((data & mask) >> shift);
data <<= 1;
}
}
static void at93c_init_op(void)
{
at93c_reg_write((at93c_reg_read() | at93c->cs) & ~at93c->clk & ~(1 << at93c->rdata_shift));
lasat_ndelay(50);
}
static void at93c_end_op(void)
{
at93c_reg_write(at93c_reg_read() & ~at93c->cs);
lasat_ndelay(250);
}
static void at93c_wait(void)
{
at93c_init_op();
while (!at93c_read_databit())
;
at93c_end_op();
};
static void at93c_disable_wp(void)
{
at93c_init_op();
at93c_write_bits(AT93C_WENCMD, 10);
at93c_end_op();
}
static void at93c_enable_wp(void)
{
at93c_init_op();
at93c_write_bits(AT93C_WDSCMD, 10);
at93c_end_op();
}
u8 at93c_read(u8 addr)
{
u8 byte;
at93c_init_op();
at93c_write_bits((addr & AT93C_ADDR_MAX)|AT93C_RCMD, 10);
byte = at93c_read_byte();
at93c_end_op();
return byte;
}
void at93c_write(u8 addr, u8 data)
{
at93c_disable_wp();
at93c_init_op();
at93c_write_bits((addr & AT93C_ADDR_MAX)|AT93C_WCMD, 10);
at93c_write_bits(data, 8);
at93c_end_op();
at93c_wait();
at93c_enable_wp();
}
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