drivers/misc/eeprom/eeprom_93cx6.c

   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
  25 MODULE_AUTHOR("http://rt2x00.serialmonkey.com");
  26 MODULE_VERSION("1.0");
  27 MODULE_DESCRIPTION("EEPROM 93cx6 chip driver");
  28 MODULE_LICENSE("GPL");
  29
  30 static 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
  43 static 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
  56 static 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
  76 static 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
  93 static 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
 132 static 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 multiple words 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  */
 181 void 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 }
 208 EXPORT_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  */
 223 void 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 }
 235 EXPORT_SYMBOL_GPL(eeprom_93cx6_multiread);
 236
 237 /**
 238  * eeprom_93cx6_wren - set the write enable state
 239  * @eeprom: Pointer to eeprom structure
 240  * @enable: true to enable writes, otherwise disable writes
 241  *
 242  * Set the EEPROM write enable state to either allow or deny
 243  * writes depending on the @enable value.
 244  */
 245 void eeprom_93cx6_wren(struct eeprom_93cx6 *eeprom, bool enable)
 246 {
 247         u16 command;
 248
 249         /* start the command */
 250         eeprom_93cx6_startup(eeprom);
 251
 252         /* create command to enable/disable */
 253
 254         command = enable ? PCI_EEPROM_EWEN_OPCODE : PCI_EEPROM_EWDS_OPCODE;
 255         command <<= (eeprom->width - 2);
 256
 257         eeprom_93cx6_write_bits(eeprom, command,
 258                                 PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
 259
 260         eeprom_93cx6_cleanup(eeprom);
 261 }
 262 EXPORT_SYMBOL_GPL(eeprom_93cx6_wren);
 263
 264 /**
 265  * eeprom_93cx6_write - write data to the EEPROM
 266  * @eeprom: Pointer to eeprom structure
 267  * @addr: Address to write data to.
 268  * @data: The data to write to address @addr.
 269  *
 270  * Write the @data to the specified @addr in the EEPROM and
 271  * waiting for the device to finish writing.
 272  *
 273  * Note, since we do not expect large number of write operations
 274  * we delay in between parts of the operation to avoid using excessive
 275  * amounts of CPU time busy waiting.
 276  */
 277 void eeprom_93cx6_write(struct eeprom_93cx6 *eeprom, u8 addr, u16 data)
 278 {
 279         int timeout = 100;
 280         u16 command;
 281
 282         /* start the command */
 283         eeprom_93cx6_startup(eeprom);
 284
 285         command = PCI_EEPROM_WRITE_OPCODE << eeprom->width;
 286         command |= addr;
 287
 288         /* send write command */
 289         eeprom_93cx6_write_bits(eeprom, command,
 290                                 PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
 291
 292         /* send data */
 293         eeprom_93cx6_write_bits(eeprom, data, 16);
 294
 295         /* get ready to check for busy */
 296         eeprom->drive_data = 0;
 297         eeprom->reg_chip_select = 1;
 298         eeprom->register_write(eeprom);
 299
 300         /* wait at-least 250ns to get DO to be the busy signal */
 301         usleep_range(1000, 2000);
 302
 303         /* wait for DO to go high to signify finish */
 304
 305         while (true) {
 306                 eeprom->register_read(eeprom);
 307
 308                 if (eeprom->reg_data_out)
 309                         break;
 310
 311                 usleep_range(1000, 2000);
 312
 313                 if (--timeout <= 0) {
 314                         printk(KERN_ERR "%s: timeout\n", __func__);
 315                         break;
 316                 }
 317         }
 318
 319         eeprom_93cx6_cleanup(eeprom);
 320 }
 321 EXPORT_SYMBOL_GPL(eeprom_93cx6_write);