aboutsummaryrefslogtreecommitdiff
path: root/board/gth/ee_access.c
blob: 2a33a0edd99aa1b17a806a9c6e395522ef424d4b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
/* Module for handling DALLAS DS2438, smart battery monitor
   Chip can store up to 40 bytes of user data in EEPROM,
   perform temp, voltage and current measurements.
   Chip also contains a unique serial number.

   Always read/write LSb first

   For documentaion, see data sheet for DS2438, 2438.pdf

   By Thomas.Lange@corelatus.com 001025 */

#include <common.h>
#include <config.h>
#include <mpc8xx.h>

#include <../board/gth/ee_dev.h>

/* We dont have kernel functions */
#define printk printf
#define KERN_DEBUG
#define KERN_ERR
#define EIO 1

static int Debug = 0;

#ifndef TRUE
#define TRUE 1
#endif
#ifndef FALSE
#define FALSE 0
#endif

/*
 * lookup table ripped from DS app note 17, understanding and using
 * cyclic redundancy checks...
 */

static u8 crc_lookup[256] = {
	0,	94,	188,	226,	97,	63,	221,	131,
	194,	156,	126,	32,	163,	253,	31,	65,
	157,	195,	33,	127,	252,	162,	64,	30,
	95,	1,	227,	189,	62,	96,	130,	220,
	35,	125,	159,	193,	66,	28,	254,	160,
	225,	191,	93,	3,	128,	222,	60,	98,
	190,	224,	2,	92,	223,	129,	99,	61,
	124,	34,	192,	158,	29,	67,	161,	255,
	70,	24,	250,	164,	39,	121,	155,	197,
	132,	218,	56,	102,	229,	187,	89,	7,
	219,	133,	103,	57,	186,	228,	6,	88,
	25,	71,	165,	251,	120,	38,	196,	154,
	101,	59,	217,	135,	4,	90,	184,	230,
	167,	249,	27,	69,	198,	152,	122,	36,
	248,	166,	68,	26,	153,	199,	37,	123,
	58,	100,	134,	216,	91,	5,	231,	185,
	140,	210,	48,	110,	237,	179,	81,	15,
	78,	16,	242,	172,	47,	113,	147,	205,
	17,	79,	173,	243,	112,	46,	204,	146,
	211,	141,	111,	49,	178,	236,	14,	80,
	175,	241,	19,	77,	206,	144,	114,	44,
	109,	51,	209,	143,	12,	82,	176,	238,
	50,	108,	142,	208,	83,	13,	239,	177,
	240,	174,	76,	18,	145,	207,	45,	115,
	202,	148,	118,	40,	171,	245,	23,	73,
	8,	86,	180,	234,	105,	55,	213,	139,
	87,	9,	235,	181,	54,	104,	138,	212,
	149,	203,	41,	119,	244,	170,	72,	22,
	233,	183,	85,	11,	136,	214,	52,	106,
	43,	117,	151,	201,	74,	20,	246,	168,
	116,	42,	200,	150,	21,	75,	169,	247,
	182,	232,	10,	84,	215,	137,	107,	53
};

static u8 make_new_crc( u8 Old_crc, u8 New_value ){
  /* Compute a new checksum with new byte, using previous checksum as input
     See DS app note 17, understanding and using cyclic redundancy checks...
     Also see DS2438, page 11 */
  return( crc_lookup[Old_crc ^ New_value ]);
}

int ee_crc_ok( u8 *Buffer, int Len, u8 Crc ){
  /* Check if the checksum for this buffer is correct */
  u8 Curr_crc=0;
  int i;
  u8 *Curr_byte = Buffer;

  for(i=0;i<Len;i++){
    Curr_crc = make_new_crc( Curr_crc, *Curr_byte);
    Curr_byte++;
  }
  E_DEBUG("Calculated CRC = 0x%x, read = 0x%x\n", Curr_crc, Crc);

  if(Curr_crc == Crc){
    /* Good */
    return(TRUE);
  }
  printk(KERN_ERR"EE checksum error, Calculated CRC = 0x%x, read = 0x%x\n",
	Curr_crc, Crc);
  return(FALSE);
}

static void
set_idle(void){
  /* Send idle and keep start time
     Continous 1 is idle */
  WRITE_PORT(1);
}

static int
do_reset(void){
  /* Release reset and verify that chip responds with presence pulse */
  int Retries = 0;
  while(Retries<5){
    udelay(RESET_LOW_TIME);

    /* Send reset */
    WRITE_PORT(0);
    udelay(RESET_LOW_TIME);

    /* Release reset */
    WRITE_PORT(1);

    /* Wait for EEPROM to drive output */
    udelay(PRESENCE_TIMEOUT);
    if(!READ_PORT){
      /* Ok, EEPROM is driving a 0 */
      E_DEBUG("Presence detected\n");
      if(Retries){
	E_DEBUG("Retries %d\n",Retries);
      }
      /* Make sure chip releases pin */
      udelay(PRESENCE_LOW_TIME);
      return 0;
    }
    Retries++;
  }

  printk(KERN_ERR"EEPROM did not respond when releasing reset\n");

    /* Make sure chip releases pin */
  udelay(PRESENCE_LOW_TIME);

  /* Set to idle again */
  set_idle();

  return(-EIO);
}

static u8
read_byte(void){
  /* Read a single byte from EEPROM
     Read LSb first */
  int i;
  int Value;
  u8 Result=0;
#ifndef CONFIG_SYS_IMMR
  u32 Flags;
#endif

  E_DEBUG("Reading byte\n");

  for(i=0;i<8;i++){
    /* Small delay between pulses */
    udelay(1);

#ifndef CONFIG_SYS_IMMR
    /* Disable irq */
    save_flags(Flags);
    cli();
#endif

    /* Pull down pin short time to start read
       See page 26 in data sheet */

    WRITE_PORT(0);
    udelay(READ_LOW);
    WRITE_PORT(1);

    /* Wait for chip to drive pin */
    udelay(READ_TIMEOUT);

    Value = READ_PORT;
    if(Value)
      Value=1;

#ifndef CONFIG_SYS_IMMR
    /* Enable irq */
    restore_flags(Flags);
#endif

    /* Wait for chip to release pin */
    udelay(TOTAL_READ_LOW-READ_TIMEOUT);

    /* LSb first */
    Result|=Value<<i;
  }

  E_DEBUG("Read byte 0x%x\n",Result);

  return(Result);
}

static void
write_byte(u8 Byte){
  /* Write a single byte to EEPROM
     Write LSb first */
  int i;
  int Value;
#ifndef CONFIG_SYS_IMMR
  u32 Flags;
#endif

  E_DEBUG("Writing byte 0x%x\n",Byte);

  for(i=0;i<8;i++){
    /* Small delay between pulses */
    udelay(1);
    Value = Byte&1;

#ifndef CONFIG_SYS_IMMR
    /* Disable irq */
    save_flags(Flags);
    cli();
#endif

    /* Pull down pin short time for a 1, long time for a 0
       See page 26 in data sheet */

    WRITE_PORT(0);
    if(Value){
      /* Write a 1 */
      udelay(WRITE_1_LOW);
    }
    else{
      /* Write a 0 */
      udelay(WRITE_0_LOW);
    }

    WRITE_PORT(1);

#ifndef CONFIG_SYS_IMMR
    /* Enable irq */
    restore_flags(Flags);
#endif

    if(Value)
      /* Wait for chip to read the 1 */
      udelay(TOTAL_WRITE_LOW-WRITE_1_LOW);
    Byte>>=1;
  }
}

int ee_do_command( u8 *Tx, int Tx_len, u8 *Rx, int Rx_len, int Send_skip ){
  /* Execute this command string, including
     giving reset and setting to idle after command
     if Rx_len is set, we read out data from EEPROM */
  int i;

  E_DEBUG("Command, Tx_len %d, Rx_len %d\n", Tx_len, Rx_len );

  if(do_reset()){
    /* Failed! */
    return(-EIO);
  }

  if(Send_skip)
    /* Always send SKIP_ROM first to tell chip we are sending a command,
       except when we read out rom data for chip */
    write_byte(SKIP_ROM);

  /* Always have Tx data */
  for(i=0;i<Tx_len;i++){
    write_byte(Tx[i]);
  }

  if(Rx_len){
    for(i=0;i<Rx_len;i++){
      Rx[i]=read_byte();
    }
  }

  set_idle();

  E_DEBUG("Command done\n");

  return(0);
}

int ee_init_data(void){
  int i;
  u8 Tx[10];
  int tmp;
  volatile immap_t *immap = (immap_t *)CONFIG_SYS_IMMR;

  while(0){
    tmp = 1-tmp;
    if(tmp)
      immap->im_ioport.iop_padat &= ~PA_FRONT_LED;
    else
      immap->im_ioport.iop_padat |= PA_FRONT_LED;
    udelay(1);
  }

  /* Set port to open drain to be able to read data from
     port without setting it to input */
  PORT_B_PAR &= ~PB_EEPROM;
  PORT_B_ODR |= PB_EEPROM;
  SET_PORT_B_OUTPUT(PB_EEPROM);

  /* Set idle mode */
  set_idle();

  /* Copy all User EEPROM data to scratchpad */
  for(i=0;i<USER_PAGES;i++){
    Tx[0]=RECALL_MEMORY;
    Tx[1]=EE_USER_PAGE_0+i;
    if(ee_do_command(Tx,2,NULL,0,TRUE)) return(-EIO);
  }

  /* Make sure chip doesnt store measurements in NVRAM */
  Tx[0]=WRITE_SCRATCHPAD;
  Tx[1]=0; /* Page */
  Tx[2]=9;
  if(ee_do_command(Tx,3,NULL,0,TRUE)) return(-EIO);

  Tx[0]=COPY_SCRATCHPAD;
  if(ee_do_command(Tx,2,NULL,0,TRUE)) return(-EIO);

  /* FIXME check status bit instead
     Could take 10 ms to store in EEPROM */
  for(i=0;i<10;i++){
    udelay(1000);
  }

  return(0);
}