You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
148 lines
2.5 KiB
148 lines
2.5 KiB
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* 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 "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();
|
|
}
|
|
|