LXR linux/arch/mips/lasat/at93c.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Atmel AT93C46 serial eeprom driver
   4 *
   5 * Brian Murphy <brian.murphy@eicon.com>
   6 *
   7 */
   8#include <linux/kernel.h>
   9#include <linux/delay.h>
  10#include <asm/lasat/lasat.h>
  11
  12#include "at93c.h"
  13
  14#define AT93C_ADDR_SHIFT        7
  15#define AT93C_ADDR_MAX          ((1 << AT93C_ADDR_SHIFT) - 1)
  16#define AT93C_RCMD              (0x6 << AT93C_ADDR_SHIFT)
  17#define AT93C_WCMD              (0x5 << AT93C_ADDR_SHIFT)
  18#define AT93C_WENCMD            0x260
  19#define AT93C_WDSCMD            0x200
  20
  21struct at93c_defs *at93c;
  22
  23static void at93c_reg_write(u32 val)
  24{
  25        *at93c->reg = val;
  26}
  27
  28static u32 at93c_reg_read(void)
  29{
  30        u32 tmp = *at93c->reg;
  31        return tmp;
  32}
  33
  34static u32 at93c_datareg_read(void)
  35{
  36        u32 tmp = *at93c->rdata_reg;
  37        return tmp;
  38}
  39
  40static void at93c_cycle_clk(u32 data)
  41{
  42        at93c_reg_write(data | at93c->clk);
  43        lasat_ndelay(250);
  44        at93c_reg_write(data & ~at93c->clk);
  45        lasat_ndelay(250);
  46}
  47
  48static void at93c_write_databit(u8 bit)
  49{
  50        u32 data = at93c_reg_read();
  51        if (bit)
  52                data |= 1 << at93c->wdata_shift;
  53        else
  54                data &= ~(1 << at93c->wdata_shift);
  55
  56        at93c_reg_write(data);
  57        lasat_ndelay(100);
  58        at93c_cycle_clk(data);
  59}
  60
  61static unsigned int at93c_read_databit(void)
  62{
  63        u32 data;
  64
  65        at93c_cycle_clk(at93c_reg_read());
  66        data = (at93c_datareg_read() >> at93c->rdata_shift) & 1;
  67        return data;
  68}
  69
  70static u8 at93c_read_byte(void)
  71{
  72        int i;
  73        u8 data = 0;
  74
  75        for (i = 0; i <= 7; i++) {
  76                data <<= 1;
  77                data |= at93c_read_databit();
  78        }
  79        return data;
  80}
  81
  82static void at93c_write_bits(u32 data, int size)
  83{
  84        int i;
  85        int shift = size - 1;
  86        u32 mask = (1 << shift);
  87
  88        for (i = 0; i < size; i++) {
  89                at93c_write_databit((data & mask) >> shift);
  90                data <<= 1;
  91        }
  92}
  93
  94static void at93c_init_op(void)
  95{
  96        at93c_reg_write((at93c_reg_read() | at93c->cs) &
  97                        ~at93c->clk & ~(1 << at93c->rdata_shift));
  98        lasat_ndelay(50);
  99}
 100
 101static void at93c_end_op(void)
 102{
 103        at93c_reg_write(at93c_reg_read() & ~at93c->cs);
 104        lasat_ndelay(250);
 105}
 106
 107static void at93c_wait(void)
 108{
 109        at93c_init_op();
 110        while (!at93c_read_databit())
 111                ;
 112        at93c_end_op();
 113};
 114
 115static void at93c_disable_wp(void)
 116{
 117        at93c_init_op();
 118        at93c_write_bits(AT93C_WENCMD, 10);
 119        at93c_end_op();
 120}
 121
 122static void at93c_enable_wp(void)
 123{
 124        at93c_init_op();
 125        at93c_write_bits(AT93C_WDSCMD, 10);
 126        at93c_end_op();
 127}
 128
 129u8 at93c_read(u8 addr)
 130{
 131        u8 byte;
 132        at93c_init_op();
 133        at93c_write_bits((addr & AT93C_ADDR_MAX)|AT93C_RCMD, 10);
 134        byte = at93c_read_byte();
 135        at93c_end_op();
 136        return byte;
 137}
 138
 139void at93c_write(u8 addr, u8 data)
 140{
 141        at93c_disable_wp();
 142        at93c_init_op();
 143        at93c_write_bits((addr & AT93C_ADDR_MAX)|AT93C_WCMD, 10);
 144        at93c_write_bits(data, 8);
 145        at93c_end_op();
 146        at93c_wait();
 147        at93c_enable_wp();
 148}
 149