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   1 /*
   2  * spi_eeprom.c
   3  * Copyright (C) 2000-2001 Toshiba Corporation
   4  *
   5  * 2003-2005 (c) MontaVista Software, Inc. This file is licensed under the
   6  * terms of the GNU General Public License version 2. This program is
   7  * licensed "as is" without any warranty of any kind, whether express
   8  * or implied.
   9  *
  10  * Support for TX4938 in 2.6 - Manish Lachwani (mlachwani@mvista.com)
  11  */
  12 #include <linux/init.h>
  13 #include <linux/device.h>
  14 #include <linux/spi/spi.h>
  15 #include <linux/spi/eeprom.h>
  16 #include <asm/txx9/spi.h>
  17
  18 #define AT250X0_PAGE_SIZE       8
  19
  20 /* register board information for at25 driver */
  21 int __init spi_eeprom_register(int busid, int chipid, int size)
  22 {
  23         struct spi_board_info info = {
  24                 .modalias = "at25",
  25                 .max_speed_hz = 1500000,        /* 1.5Mbps */
  26                 .bus_num = busid,
  27                 .chip_select = chipid,
  28                 /* Mode 0: High-Active, Sample-Then-Shift */
  29         };
  30         struct spi_eeprom *eeprom;
  31         eeprom = kzalloc(sizeof(*eeprom), GFP_KERNEL);
  32         if (!eeprom)
  33                 return -ENOMEM;
  34         strcpy(eeprom->name, "at250x0");
  35         eeprom->byte_len = size;
  36         eeprom->page_size = AT250X0_PAGE_SIZE;
  37         eeprom->flags = EE_ADDR1;
  38         info.platform_data = eeprom;
  39         return spi_register_board_info(&info, 1);
  40 }
  41
  42 /* simple temporary spi driver to provide early access to seeprom. */
  43
  44 static struct read_param {
  45         int busid;
  46         int chipid;
  47         int address;
  48         unsigned char *buf;
  49         int len;
  50 } *read_param;
  51
  52 static int __init early_seeprom_probe(struct spi_device *spi)
  53 {
  54         int stat = 0;
  55         u8 cmd[2];
  56         int len = read_param->len;
  57         char *buf = read_param->buf;
  58         int address = read_param->address;
  59
  60         dev_info(&spi->dev, "spiclk %u KHz.\n",
  61                  (spi->max_speed_hz + 500) / 1000);
  62         if (read_param->busid != spi->master->bus_num ||
  63             read_param->chipid != spi->chip_select)
  64                 return -ENODEV;
  65         while (len > 0) {
  66                 /* spi_write_then_read can only work with small chunk */
  67                 int c = len < AT250X0_PAGE_SIZE ? len : AT250X0_PAGE_SIZE;
  68                 cmd[0] = 0x03;  /* AT25_READ */
  69                 cmd[1] = address;
  70                 stat = spi_write_then_read(spi, cmd, sizeof(cmd), buf, c);
  71                 buf += c;
  72                 len -= c;
  73                 address += c;
  74         }
  75         return stat;
  76 }
  77
  78 static struct spi_driver early_seeprom_driver __initdata = {
  79         .driver = {
  80                 .name   = "at25",
  81                 .owner  = THIS_MODULE,
  82         },
  83         .probe  = early_seeprom_probe,
  84 };
  85
  86 int __init spi_eeprom_read(int busid, int chipid, int address,
  87                            unsigned char *buf, int len)
  88 {
  89         int ret;
  90         struct read_param param = {
  91                 .busid = busid,
  92                 .chipid = chipid,
  93                 .address = address,
  94                 .buf = buf,
  95                 .len = len
  96         };
  97
  98         read_param = &param;
  99         ret = spi_register_driver(&early_seeprom_driver);
 100         if (!ret)
 101                 spi_unregister_driver(&early_seeprom_driver);
 102         return ret;
 103 }