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