149 lines
2.5 KiB
C
149 lines
2.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Atmel AT93C46 serial eeprom driver
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*
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* Brian Murphy <brian.murphy@eicon.com>
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*
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*/
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#include <linux/kernel.h>
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#include <linux/delay.h>
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#include <asm/lasat/lasat.h>
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#include "at93c.h"
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#define AT93C_ADDR_SHIFT 7
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#define AT93C_ADDR_MAX ((1 << AT93C_ADDR_SHIFT) - 1)
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#define AT93C_RCMD (0x6 << AT93C_ADDR_SHIFT)
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#define AT93C_WCMD (0x5 << AT93C_ADDR_SHIFT)
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#define AT93C_WENCMD 0x260
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#define AT93C_WDSCMD 0x200
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struct at93c_defs *at93c;
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static void at93c_reg_write(u32 val)
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{
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*at93c->reg = val;
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}
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static u32 at93c_reg_read(void)
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{
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u32 tmp = *at93c->reg;
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return tmp;
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}
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static u32 at93c_datareg_read(void)
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{
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u32 tmp = *at93c->rdata_reg;
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return tmp;
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}
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static void at93c_cycle_clk(u32 data)
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{
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at93c_reg_write(data | at93c->clk);
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lasat_ndelay(250);
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at93c_reg_write(data & ~at93c->clk);
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lasat_ndelay(250);
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}
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static void at93c_write_databit(u8 bit)
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{
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u32 data = at93c_reg_read();
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if (bit)
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data |= 1 << at93c->wdata_shift;
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else
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data &= ~(1 << at93c->wdata_shift);
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at93c_reg_write(data);
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lasat_ndelay(100);
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at93c_cycle_clk(data);
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}
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static unsigned int at93c_read_databit(void)
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{
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u32 data;
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at93c_cycle_clk(at93c_reg_read());
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data = (at93c_datareg_read() >> at93c->rdata_shift) & 1;
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return data;
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}
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static u8 at93c_read_byte(void)
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{
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int i;
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u8 data = 0;
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for (i = 0; i <= 7; i++) {
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data <<= 1;
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data |= at93c_read_databit();
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}
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return data;
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}
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static void at93c_write_bits(u32 data, int size)
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{
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int i;
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int shift = size - 1;
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u32 mask = (1 << shift);
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for (i = 0; i < size; i++) {
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at93c_write_databit((data & mask) >> shift);
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data <<= 1;
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}
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}
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static void at93c_init_op(void)
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{
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at93c_reg_write((at93c_reg_read() | at93c->cs) &
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~at93c->clk & ~(1 << at93c->rdata_shift));
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lasat_ndelay(50);
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}
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static void at93c_end_op(void)
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{
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at93c_reg_write(at93c_reg_read() & ~at93c->cs);
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lasat_ndelay(250);
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}
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static void at93c_wait(void)
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{
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at93c_init_op();
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while (!at93c_read_databit())
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;
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at93c_end_op();
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};
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static void at93c_disable_wp(void)
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{
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at93c_init_op();
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at93c_write_bits(AT93C_WENCMD, 10);
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at93c_end_op();
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}
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static void at93c_enable_wp(void)
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{
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at93c_init_op();
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at93c_write_bits(AT93C_WDSCMD, 10);
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at93c_end_op();
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}
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u8 at93c_read(u8 addr)
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{
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u8 byte;
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at93c_init_op();
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at93c_write_bits((addr & AT93C_ADDR_MAX)|AT93C_RCMD, 10);
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byte = at93c_read_byte();
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at93c_end_op();
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return byte;
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}
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void at93c_write(u8 addr, u8 data)
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{
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at93c_disable_wp();
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at93c_init_op();
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at93c_write_bits((addr & AT93C_ADDR_MAX)|AT93C_WCMD, 10);
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at93c_write_bits(data, 8);
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at93c_end_op();
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at93c_wait();
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at93c_enable_wp();
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}
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