linux/drivers/misc/eeprom/eeprom_93cx6.c
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   1/*
   2 * Copyright (C) 2004 - 2006 rt2x00 SourceForge Project
   3 * <http://rt2x00.serialmonkey.com>
   4 *
   5 * This program is free software; you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License as published by
   7 * the Free Software Foundation; either version 2 of the License, or
   8 * (at your option) any later version.
   9 *
  10 * This program is distributed in the hope that it will be useful,
  11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13 * GNU General Public License for more details.
  14 *
  15 * Module: eeprom_93cx6
  16 * Abstract: EEPROM reader routines for 93cx6 chipsets.
  17 * Supported chipsets: 93c46 & 93c66.
  18 */
  19
  20#include <linux/kernel.h>
  21#include <linux/module.h>
  22#include <linux/delay.h>
  23#include <linux/eeprom_93cx6.h>
  24
  25MODULE_AUTHOR("http://rt2x00.serialmonkey.com");
  26MODULE_VERSION("1.0");
  27MODULE_DESCRIPTION("EEPROM 93cx6 chip driver");
  28MODULE_LICENSE("GPL");
  29
  30static inline void eeprom_93cx6_pulse_high(struct eeprom_93cx6 *eeprom)
  31{
  32        eeprom->reg_data_clock = 1;
  33        eeprom->register_write(eeprom);
  34
  35        /*
  36         * Add a short delay for the pulse to work.
  37         * According to the specifications the "maximum minimum"
  38         * time should be 450ns.
  39         */
  40        ndelay(450);
  41}
  42
  43static inline void eeprom_93cx6_pulse_low(struct eeprom_93cx6 *eeprom)
  44{
  45        eeprom->reg_data_clock = 0;
  46        eeprom->register_write(eeprom);
  47
  48        /*
  49         * Add a short delay for the pulse to work.
  50         * According to the specifications the "maximum minimum"
  51         * time should be 450ns.
  52         */
  53        ndelay(450);
  54}
  55
  56static void eeprom_93cx6_startup(struct eeprom_93cx6 *eeprom)
  57{
  58        /*
  59         * Clear all flags, and enable chip select.
  60         */
  61        eeprom->register_read(eeprom);
  62        eeprom->reg_data_in = 0;
  63        eeprom->reg_data_out = 0;
  64        eeprom->reg_data_clock = 0;
  65        eeprom->reg_chip_select = 1;
  66        eeprom->drive_data = 1;
  67        eeprom->register_write(eeprom);
  68
  69        /*
  70         * kick a pulse.
  71         */
  72        eeprom_93cx6_pulse_high(eeprom);
  73        eeprom_93cx6_pulse_low(eeprom);
  74}
  75
  76static void eeprom_93cx6_cleanup(struct eeprom_93cx6 *eeprom)
  77{
  78        /*
  79         * Clear chip_select and data_in flags.
  80         */
  81        eeprom->register_read(eeprom);
  82        eeprom->reg_data_in = 0;
  83        eeprom->reg_chip_select = 0;
  84        eeprom->register_write(eeprom);
  85
  86        /*
  87         * kick a pulse.
  88         */
  89        eeprom_93cx6_pulse_high(eeprom);
  90        eeprom_93cx6_pulse_low(eeprom);
  91}
  92
  93static void eeprom_93cx6_write_bits(struct eeprom_93cx6 *eeprom,
  94        const u16 data, const u16 count)
  95{
  96        unsigned int i;
  97
  98        eeprom->register_read(eeprom);
  99
 100        /*
 101         * Clear data flags.
 102         */
 103        eeprom->reg_data_in = 0;
 104        eeprom->reg_data_out = 0;
 105        eeprom->drive_data = 1;
 106
 107        /*
 108         * Start writing all bits.
 109         */
 110        for (i = count; i > 0; i--) {
 111                /*
 112                 * Check if this bit needs to be set.
 113                 */
 114                eeprom->reg_data_in = !!(data & (1 << (i - 1)));
 115
 116                /*
 117                 * Write the bit to the eeprom register.
 118                 */
 119                eeprom->register_write(eeprom);
 120
 121                /*
 122                 * Kick a pulse.
 123                 */
 124                eeprom_93cx6_pulse_high(eeprom);
 125                eeprom_93cx6_pulse_low(eeprom);
 126        }
 127
 128        eeprom->reg_data_in = 0;
 129        eeprom->register_write(eeprom);
 130}
 131
 132static void eeprom_93cx6_read_bits(struct eeprom_93cx6 *eeprom,
 133        u16 *data, const u16 count)
 134{
 135        unsigned int i;
 136        u16 buf = 0;
 137
 138        eeprom->register_read(eeprom);
 139
 140        /*
 141         * Clear data flags.
 142         */
 143        eeprom->reg_data_in = 0;
 144        eeprom->reg_data_out = 0;
 145        eeprom->drive_data = 0;
 146
 147        /*
 148         * Start reading all bits.
 149         */
 150        for (i = count; i > 0; i--) {
 151                eeprom_93cx6_pulse_high(eeprom);
 152
 153                eeprom->register_read(eeprom);
 154
 155                /*
 156                 * Clear data_in flag.
 157                 */
 158                eeprom->reg_data_in = 0;
 159
 160                /*
 161                 * Read if the bit has been set.
 162                 */
 163                if (eeprom->reg_data_out)
 164                        buf |= (1 << (i - 1));
 165
 166                eeprom_93cx6_pulse_low(eeprom);
 167        }
 168
 169        *data = buf;
 170}
 171
 172/**
 173 * eeprom_93cx6_read - Read a word from eeprom
 174 * @eeprom: Pointer to eeprom structure
 175 * @word: Word index from where we should start reading
 176 * @data: target pointer where the information will have to be stored
 177 *
 178 * This function will read the eeprom data as host-endian word
 179 * into the given data pointer.
 180 */
 181void eeprom_93cx6_read(struct eeprom_93cx6 *eeprom, const u8 word,
 182        u16 *data)
 183{
 184        u16 command;
 185
 186        /*
 187         * Initialize the eeprom register
 188         */
 189        eeprom_93cx6_startup(eeprom);
 190
 191        /*
 192         * Select the read opcode and the word to be read.
 193         */
 194        command = (PCI_EEPROM_READ_OPCODE << eeprom->width) | word;
 195        eeprom_93cx6_write_bits(eeprom, command,
 196                PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
 197
 198        /*
 199         * Read the requested 16 bits.
 200         */
 201        eeprom_93cx6_read_bits(eeprom, data, 16);
 202
 203        /*
 204         * Cleanup eeprom register.
 205         */
 206        eeprom_93cx6_cleanup(eeprom);
 207}
 208EXPORT_SYMBOL_GPL(eeprom_93cx6_read);
 209
 210/**
 211 * eeprom_93cx6_multiread - Read multiple words from eeprom
 212 * @eeprom: Pointer to eeprom structure
 213 * @word: Word index from where we should start reading
 214 * @data: target pointer where the information will have to be stored
 215 * @words: Number of words that should be read.
 216 *
 217 * This function will read all requested words from the eeprom,
 218 * this is done by calling eeprom_93cx6_read() multiple times.
 219 * But with the additional change that while the eeprom_93cx6_read
 220 * will return host ordered bytes, this method will return little
 221 * endian words.
 222 */
 223void eeprom_93cx6_multiread(struct eeprom_93cx6 *eeprom, const u8 word,
 224        __le16 *data, const u16 words)
 225{
 226        unsigned int i;
 227        u16 tmp;
 228
 229        for (i = 0; i < words; i++) {
 230                tmp = 0;
 231                eeprom_93cx6_read(eeprom, word + i, &tmp);
 232                data[i] = cpu_to_le16(tmp);
 233        }
 234}
 235EXPORT_SYMBOL_GPL(eeprom_93cx6_multiread);
 236
 237/**
 238 * eeprom_93cx6_readb - Read a byte from eeprom
 239 * @eeprom: Pointer to eeprom structure
 240 * @word: Byte index from where we should start reading
 241 * @data: target pointer where the information will have to be stored
 242 *
 243 * This function will read a byte of the eeprom data
 244 * into the given data pointer.
 245 */
 246void eeprom_93cx6_readb(struct eeprom_93cx6 *eeprom, const u8 byte,
 247        u8 *data)
 248{
 249        u16 command;
 250        u16 tmp;
 251
 252        /*
 253         * Initialize the eeprom register
 254         */
 255        eeprom_93cx6_startup(eeprom);
 256
 257        /*
 258         * Select the read opcode and the byte to be read.
 259         */
 260        command = (PCI_EEPROM_READ_OPCODE << (eeprom->width + 1)) | byte;
 261        eeprom_93cx6_write_bits(eeprom, command,
 262                PCI_EEPROM_WIDTH_OPCODE + eeprom->width + 1);
 263
 264        /*
 265         * Read the requested 8 bits.
 266         */
 267        eeprom_93cx6_read_bits(eeprom, &tmp, 8);
 268        *data = tmp & 0xff;
 269
 270        /*
 271         * Cleanup eeprom register.
 272         */
 273        eeprom_93cx6_cleanup(eeprom);
 274}
 275EXPORT_SYMBOL_GPL(eeprom_93cx6_readb);
 276
 277/**
 278 * eeprom_93cx6_multireadb - Read multiple bytes from eeprom
 279 * @eeprom: Pointer to eeprom structure
 280 * @byte: Index from where we should start reading
 281 * @data: target pointer where the information will have to be stored
 282 * @words: Number of bytes that should be read.
 283 *
 284 * This function will read all requested bytes from the eeprom,
 285 * this is done by calling eeprom_93cx6_readb() multiple times.
 286 */
 287void eeprom_93cx6_multireadb(struct eeprom_93cx6 *eeprom, const u8 byte,
 288        u8 *data, const u16 bytes)
 289{
 290        unsigned int i;
 291
 292        for (i = 0; i < bytes; i++)
 293                eeprom_93cx6_readb(eeprom, byte + i, &data[i]);
 294}
 295EXPORT_SYMBOL_GPL(eeprom_93cx6_multireadb);
 296
 297/**
 298 * eeprom_93cx6_wren - set the write enable state
 299 * @eeprom: Pointer to eeprom structure
 300 * @enable: true to enable writes, otherwise disable writes
 301 *
 302 * Set the EEPROM write enable state to either allow or deny
 303 * writes depending on the @enable value.
 304 */
 305void eeprom_93cx6_wren(struct eeprom_93cx6 *eeprom, bool enable)
 306{
 307        u16 command;
 308
 309        /* start the command */
 310        eeprom_93cx6_startup(eeprom);
 311
 312        /* create command to enable/disable */
 313
 314        command = enable ? PCI_EEPROM_EWEN_OPCODE : PCI_EEPROM_EWDS_OPCODE;
 315        command <<= (eeprom->width - 2);
 316
 317        eeprom_93cx6_write_bits(eeprom, command,
 318                                PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
 319
 320        eeprom_93cx6_cleanup(eeprom);
 321}
 322EXPORT_SYMBOL_GPL(eeprom_93cx6_wren);
 323
 324/**
 325 * eeprom_93cx6_write - write data to the EEPROM
 326 * @eeprom: Pointer to eeprom structure
 327 * @addr: Address to write data to.
 328 * @data: The data to write to address @addr.
 329 *
 330 * Write the @data to the specified @addr in the EEPROM and
 331 * waiting for the device to finish writing.
 332 *
 333 * Note, since we do not expect large number of write operations
 334 * we delay in between parts of the operation to avoid using excessive
 335 * amounts of CPU time busy waiting.
 336 */
 337void eeprom_93cx6_write(struct eeprom_93cx6 *eeprom, u8 addr, u16 data)
 338{
 339        int timeout = 100;
 340        u16 command;
 341
 342        /* start the command */
 343        eeprom_93cx6_startup(eeprom);
 344
 345        command = PCI_EEPROM_WRITE_OPCODE << eeprom->width;
 346        command |= addr;
 347
 348        /* send write command */
 349        eeprom_93cx6_write_bits(eeprom, command,
 350                                PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
 351
 352        /* send data */
 353        eeprom_93cx6_write_bits(eeprom, data, 16);
 354
 355        /* get ready to check for busy */
 356        eeprom->drive_data = 0;
 357        eeprom->reg_chip_select = 1;
 358        eeprom->register_write(eeprom);
 359
 360        /* wait at-least 250ns to get DO to be the busy signal */
 361        usleep_range(1000, 2000);
 362
 363        /* wait for DO to go high to signify finish */
 364
 365        while (true) {
 366                eeprom->register_read(eeprom);
 367
 368                if (eeprom->reg_data_out)
 369                        break;
 370
 371                usleep_range(1000, 2000);
 372
 373                if (--timeout <= 0) {
 374                        printk(KERN_ERR "%s: timeout\n", __func__);
 375                        break;
 376                }
 377        }
 378
 379        eeprom_93cx6_cleanup(eeprom);
 380}
 381EXPORT_SYMBOL_GPL(eeprom_93cx6_write);
 382