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->register_write(eeprom);
  67
  68         /*
  69          * kick a pulse.
  70          */
  71         eeprom_93cx6_pulse_high(eeprom);
  72         eeprom_93cx6_pulse_low(eeprom);
  73 }
  74
  75 static void eeprom_93cx6_cleanup(struct eeprom_93cx6 *eeprom)
  76 {
  77         /*
  78          * Clear chip_select and data_in flags.
  79          */
  80         eeprom->register_read(eeprom);
  81         eeprom->reg_data_in = 0;
  82         eeprom->reg_chip_select = 0;
  83         eeprom->register_write(eeprom);
  84
  85         /*
  86          * kick a pulse.
  87          */
  88         eeprom_93cx6_pulse_high(eeprom);
  89         eeprom_93cx6_pulse_low(eeprom);
  90 }
  91
  92 static void eeprom_93cx6_write_bits(struct eeprom_93cx6 *eeprom,
  93         const u16 data, const u16 count)
  94 {
  95         unsigned int i;
  96
  97         eeprom->register_read(eeprom);
  98
  99         /*
 100          * Clear data flags.
 101          */
 102         eeprom->reg_data_in = 0;
 103         eeprom->reg_data_out = 0;
 104
 105         /*
 106          * Start writing all bits.
 107          */
 108         for (i = count; i > 0; i--) {
 109                 /*
 110                  * Check if this bit needs to be set.
 111                  */
 112                 eeprom->reg_data_in = !!(data & (1 << (i - 1)));
 113
 114                 /*
 115                  * Write the bit to the eeprom register.
 116                  */
 117                 eeprom->register_write(eeprom);
 118
 119                 /*
 120                  * Kick a pulse.
 121                  */
 122                 eeprom_93cx6_pulse_high(eeprom);
 123                 eeprom_93cx6_pulse_low(eeprom);
 124         }
 125
 126         eeprom->reg_data_in = 0;
 127         eeprom->register_write(eeprom);
 128 }
 129
 130 static void eeprom_93cx6_read_bits(struct eeprom_93cx6 *eeprom,
 131         u16 *data, const u16 count)
 132 {
 133         unsigned int i;
 134         u16 buf = 0;
 135
 136         eeprom->register_read(eeprom);
 137
 138         /*
 139          * Clear data flags.
 140          */
 141         eeprom->reg_data_in = 0;
 142         eeprom->reg_data_out = 0;
 143
 144         /*
 145          * Start reading all bits.
 146          */
 147         for (i = count; i > 0; i--) {
 148                 eeprom_93cx6_pulse_high(eeprom);
 149
 150                 eeprom->register_read(eeprom);
 151
 152                 /*
 153                  * Clear data_in flag.
 154                  */
 155                 eeprom->reg_data_in = 0;
 156
 157                 /*
 158                  * Read if the bit has been set.
 159                  */
 160                 if (eeprom->reg_data_out)
 161                         buf |= (1 << (i - 1));
 162
 163                 eeprom_93cx6_pulse_low(eeprom);
 164         }
 165
 166         *data = buf;
 167 }
 168
 169 /**
 170  * eeprom_93cx6_read - Read multiple words from eeprom
 171  * @eeprom: Pointer to eeprom structure
 172  * @word: Word index from where we should start reading
 173  * @data: target pointer where the information will have to be stored
 174  *
 175  * This function will read the eeprom data as host-endian word
 176  * into the given data pointer.
 177  */
 178 void eeprom_93cx6_read(struct eeprom_93cx6 *eeprom, const u8 word,
 179         u16 *data)
 180 {
 181         u16 command;
 182
 183         /*
 184          * Initialize the eeprom register
 185          */
 186         eeprom_93cx6_startup(eeprom);
 187
 188         /*
 189          * Select the read opcode and the word to be read.
 190          */
 191         command = (PCI_EEPROM_READ_OPCODE << eeprom->width) | word;
 192         eeprom_93cx6_write_bits(eeprom, command,
 193                 PCI_EEPROM_WIDTH_OPCODE + eeprom->width);
 194
 195         /*
 196          * Read the requested 16 bits.
 197          */
 198         eeprom_93cx6_read_bits(eeprom, data, 16);
 199
 200         /*
 201          * Cleanup eeprom register.
 202          */
 203         eeprom_93cx6_cleanup(eeprom);
 204 }
 205 EXPORT_SYMBOL_GPL(eeprom_93cx6_read);
 206
 207 /**
 208  * eeprom_93cx6_multiread - Read multiple words from eeprom
 209  * @eeprom: Pointer to eeprom structure
 210  * @word: Word index from where we should start reading
 211  * @data: target pointer where the information will have to be stored
 212  * @words: Number of words that should be read.
 213  *
 214  * This function will read all requested words from the eeprom,
 215  * this is done by calling eeprom_93cx6_read() multiple times.
 216  * But with the additional change that while the eeprom_93cx6_read
 217  * will return host ordered bytes, this method will return little
 218  * endian words.
 219  */
 220 void eeprom_93cx6_multiread(struct eeprom_93cx6 *eeprom, const u8 word,
 221         __le16 *data, const u16 words)
 222 {
 223         unsigned int i;
 224         u16 tmp;
 225
 226         for (i = 0; i < words; i++) {
 227                 tmp = 0;
 228                 eeprom_93cx6_read(eeprom, word + i, &tmp);
 229                 data[i] = cpu_to_le16(tmp);
 230         }
 231 }
 232 EXPORT_SYMBOL_GPL(eeprom_93cx6_multiread);
 233