arch/mips/lasat/at93c.c

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