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spi_eeprom.c

/*
 * spi_eeprom.c
 * Copyright (C) 2000-2001 Toshiba Corporation
 *
 * 2003-2005 (c) MontaVista Software, Inc. This file is licensed under the
 * terms of the GNU General Public License version 2. This program is
 * licensed "as is" without any warranty of any kind, whether express
 * or implied.
 *
 * Support for TX4938 in 2.6 - Manish Lachwani (mlachwani@mvista.com)
 */
#include <linux/init.h>
#include <linux/device.h>
#include <linux/spi/spi.h>
#include <linux/spi/eeprom.h>
#include <asm/txx9/spi.h>

#define AT250X0_PAGE_SIZE     8

/* register board information for at25 driver */
int __init spi_eeprom_register(int chipid)
{
      static struct spi_eeprom eeprom = {
            .name = "at250x0",
            .byte_len = 128,
            .page_size = AT250X0_PAGE_SIZE,
            .flags = EE_ADDR1,
      };
      struct spi_board_info info = {
            .modalias = "at25",
            .max_speed_hz = 1500000,      /* 1.5Mbps */
            .bus_num = 0,
            .chip_select = chipid,
            .platform_data = &eeprom,
            /* Mode 0: High-Active, Sample-Then-Shift */
      };

      return spi_register_board_info(&info, 1);
}

/* simple temporary spi driver to provide early access to seeprom. */

static struct read_param {
      int chipid;
      int address;
      unsigned char *buf;
      int len;
} *read_param;

static int __init early_seeprom_probe(struct spi_device *spi)
{
      int stat = 0;
      u8 cmd[2];
      int len = read_param->len;
      char *buf = read_param->buf;
      int address = read_param->address;

      dev_info(&spi->dev, "spiclk %u KHz.\n",
             (spi->max_speed_hz + 500) / 1000);
      if (read_param->chipid != spi->chip_select)
            return -ENODEV;
      while (len > 0) {
            /* spi_write_then_read can only work with small chunk */
            int c = len < AT250X0_PAGE_SIZE ? len : AT250X0_PAGE_SIZE;
            cmd[0] = 0x03;    /* AT25_READ */
            cmd[1] = address;
            stat = spi_write_then_read(spi, cmd, sizeof(cmd), buf, c);
            buf += c;
            len -= c;
            address += c;
      }
      return stat;
}

static struct spi_driver early_seeprom_driver __initdata = {
      .driver = {
            .name = "at25",
            .owner      = THIS_MODULE,
      },
      .probe      = early_seeprom_probe,
};

int __init spi_eeprom_read(int chipid, int address,
                     unsigned char *buf, int len)
{
      int ret;
      struct read_param param = {
            .chipid = chipid,
            .address = address,
            .buf = buf,
            .len = len
      };

      read_param = &param;
      ret = spi_register_driver(&early_seeprom_driver);
      if (!ret)
            spi_unregister_driver(&early_seeprom_driver);
      return ret;
}

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