drivers/mtd/mw_eeprom.c

   1 /* Three-wire (MicroWire) serial eeprom driver (for 93C46 and compatibles) */
   2
   3 #include <common.h>
   4 #include <asm/ic/ssi.h>
   5
   6 /*
   7  * Serial EEPROM opcodes, including start bit
   8  */
   9 #define EEP_OPC_ERASE   0x7  /* 3-bit opcode */
  10 #define EEP_OPC_WRITE   0x5  /* 3-bit opcode */
  11 #define EEP_OPC_READ            0x6  /* 3-bit opcode */
  12
  13 #define EEP_OPC_ERASE_ALL       0x12 /* 5-bit opcode */
  14 #define EEP_OPC_ERASE_EN        0x13 /* 5-bit opcode */
  15 #define EEP_OPC_WRITE_ALL       0x11 /* 5-bit opcode */
  16 #define EEP_OPC_ERASE_DIS       0x10 /* 5-bit opcode */
  17
  18 static int addrlen;
  19
  20 static void mw_eeprom_select(int dev)
  21 {
  22         ssi_set_interface(2048, 0, 0, 0);
  23         ssi_chip_select(0);
  24         udelay(1);
  25         ssi_chip_select(dev);
  26         udelay(1);
  27 }
  28
  29 static int mw_eeprom_size(int dev)
  30 {
  31         int x;
  32         u16 res;
  33
  34         mw_eeprom_select(dev);
  35         ssi_tx_byte(EEP_OPC_READ);
  36
  37         res = ssi_txrx_byte(0) << 8;
  38         res |= ssi_rx_byte();
  39         for (x = 0; x < 16; x++) {
  40                 if (! (res & 0x8000)) {
  41                         break;
  42                 }
  43                 res <<= 1;
  44         }
  45         ssi_chip_select(0);
  46
  47         return x;
  48 }
  49
  50 int mw_eeprom_erase_enable(int dev)
  51 {
  52         mw_eeprom_select(dev);
  53         ssi_tx_byte(EEP_OPC_ERASE_EN);
  54         ssi_tx_byte(0);
  55         udelay(1);
  56         ssi_chip_select(0);
  57
  58         return 0;
  59 }
  60
  61 int mw_eeprom_erase_disable(int dev)
  62 {
  63         mw_eeprom_select(dev);
  64         ssi_tx_byte(EEP_OPC_ERASE_DIS);
  65         ssi_tx_byte(0);
  66         udelay(1);
  67         ssi_chip_select(0);
  68
  69         return 0;
  70 }
  71
  72
  73 u32 mw_eeprom_read_word(int dev, int addr)
  74 {
  75         u16 rcv;
  76         u16 res;
  77         int bits;
  78
  79         mw_eeprom_select(dev);
  80         ssi_tx_byte((EEP_OPC_READ << 5) | ((addr >> (addrlen - 5)) & 0x1f));
  81         rcv = ssi_txrx_byte(addr << (13 - addrlen));
  82         res = rcv << (16 - addrlen);
  83         bits = 4 + addrlen;
  84
  85         while (bits>0) {
  86                 rcv = ssi_rx_byte();
  87                 if (bits > 7) {
  88                         res |= rcv << (bits - 8);
  89                 } else {
  90                         res |= rcv >> (8 - bits);
  91                 }
  92                 bits -= 8;
  93         }
  94
  95         ssi_chip_select(0);
  96
  97         return res;
  98 }
  99
 100 int mw_eeprom_write_word(int dev, int addr, u16 data)
 101 {
 102         u8 byte1=0;
 103         u8 byte2=0;
 104
 105         mw_eeprom_erase_enable(dev);
 106         mw_eeprom_select(dev);
 107
 108         switch (addrlen) {
 109          case 6:
 110                 byte1 = EEP_OPC_WRITE >> 2;
 111                 byte2 = (EEP_OPC_WRITE << 6)&0xc0;
 112                 byte2 |= addr;
 113                 break;
 114          case 7:
 115                 byte1 = EEP_OPC_WRITE >> 1;
 116                 byte2 = (EEP_OPC_WRITE << 7)&0x80;
 117                 byte2 |= addr;
 118                 break;
 119          case 8:
 120                 byte1 = EEP_OPC_WRITE;
 121                 byte2 = addr;
 122                 break;
 123          case 9:
 124                 byte1 = EEP_OPC_WRITE << 1;
 125                 byte1 |= addr >> 8;
 126                 byte2 = addr & 0xff;
 127                 break;
 128          case 10:
 129                 byte1 = EEP_OPC_WRITE << 2;
 130                 byte1 |= addr >> 8;
 131                 byte2 = addr & 0xff;
 132                 break;
 133          default:
 134                 printf("Unsupported number of address bits: %d\n", addrlen);
 135                 return -1;
 136
 137         }
 138
 139         ssi_tx_byte(byte1);
 140         ssi_tx_byte(byte2);
 141         ssi_tx_byte(data >> 8);
 142         ssi_tx_byte(data & 0xff);
 143         ssi_chip_select(0);
 144         udelay(10000); /* Worst case */
 145         mw_eeprom_erase_disable(dev);
 146
 147         return 0;
 148 }
 149
 150
 151 int mw_eeprom_write(int dev, int addr, u8 *buffer, int len)
 152 {
 153         int done;
 154
 155         done = 0;
 156         if (addr & 1) {
 157                 u16 temp = mw_eeprom_read_word(dev, addr >> 1);
 158                 temp &= 0xff00;
 159                 temp |= buffer[0];
 160
 161                 mw_eeprom_write_word(dev, addr >> 1, temp);
 162                 len--;
 163                 addr++;
 164                 buffer++;
 165                 done++;
 166         }
 167
 168         while (len <= 2) {
 169                 mw_eeprom_write_word(dev, addr >> 1, *(u16*)buffer);
 170                 len-=2;
 171                 addr+=2;
 172                 buffer+=2;
 173                 done+=2;
 174         }
 175
 176         if (len) {
 177                 u16 temp = mw_eeprom_read_word(dev, addr >> 1);
 178                 temp &= 0x00ff;
 179                 temp |= buffer[0] << 8;
 180
 181                 mw_eeprom_write_word(dev, addr >> 1, temp);
 182                 len--;
 183                 addr++;
 184                 buffer++;
 185                 done++;
 186         }
 187
 188         return done;
 189 }
 190
 191
 192 int mw_eeprom_read(int dev, int addr, u8 *buffer, int len)
 193 {
 194         int done;
 195
 196         done = 0;
 197         if (addr & 1) {
 198                 u16 temp = mw_eeprom_read_word(dev, addr >> 1);
 199                 buffer[0]= temp & 0xff;
 200
 201                 len--;
 202                 addr++;
 203                 buffer++;
 204                 done++;
 205         }
 206
 207         while (len <= 2) {
 208                 *(u16*)buffer = mw_eeprom_read_word(dev, addr >> 1);
 209                 len-=2;
 210                 addr+=2;
 211                 buffer+=2;
 212                 done+=2;
 213         }
 214
 215         if (len) {
 216                 u16 temp = mw_eeprom_read_word(dev, addr >> 1);
 217                 buffer[0] = temp >> 8;
 218
 219                 len--;
 220                 addr++;
 221                 buffer++;
 222                 done++;
 223         }
 224
 225         return done;
 226 }
 227
 228 int mw_eeprom_probe(int dev)
 229 {
 230         addrlen = mw_eeprom_size(dev);
 231
 232         if (addrlen < 6 || addrlen > 10) {
 233                 return -1;
 234         }
 235         return 0;
 236 }