spi_eeprom.c

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/*
 * 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 ([email protected])
 */
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/export.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 busid, int chipid, int size)
{
    struct spi_board_info info = {
        .modalias = "at25",
        .max_speed_hz = 1500000,    /* 1.5Mbps */
        .bus_num = busid,
        .chip_select = chipid,
        /* Mode 0: High-Active, Sample-Then-Shift */
    };
    struct spi_eeprom *eeprom;
    eeprom = kzalloc(sizeof(*eeprom), GFP_KERNEL);
    if (!eeprom)
        return -ENOMEM;
    strcpy(eeprom->name, "at250x0");
    eeprom->byte_len = size;
    eeprom->page_size = AT250X0_PAGE_SIZE;
    eeprom->flags = EE_ADDR1;
    info.platform_data = eeprom;
    return spi_register_board_info(&info, 1);
}

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

static struct read_param {
    int busid;
    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->busid != spi->master->bus_num ||
        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 busid, int chipid, int address,
               unsigned char *buf, int len)
{
    int ret;
    struct read_param param = {
        .busid = busid,
        .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;
}