linux-imx

// SPDX-License-Identifier: GPL-2.0-only

/*

 * max6875.c - driver for MAX6874/MAX6875

 *

 * Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>

 *

 * Based on eeprom.c

 *

 * The MAX6875 has a bank of registers and two banks of EEPROM.

 * Address ranges are defined as follows:

 *  * 0x0000 - 0x0046 = configuration registers

 *  * 0x8000 - 0x8046 = configuration EEPROM

 *  * 0x8100 - 0x82FF = user EEPROM

 *

 * This driver makes the user EEPROM available for read.

 *

 * The registers & config EEPROM should be accessed via i2c-dev.

 *

 * The MAX6875 ignores the lowest address bit, so each chip responds to

 * two addresses - 0x50/0x51 and 0x52/0x53.

 *

 * Note that the MAX6875 uses i2c_smbus_write_byte_data() to set the read

 * address, so this driver is destructive if loaded for the wrong EEPROM chip.

 */

​

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/slab.h>

#include <linux/i2c.h>

#include <linux/mutex.h>

​

/* The MAX6875 can only read/write 16 bytes at a time */

#define SLICE_SIZE          16

#define SLICE_BITS          4

​

/* USER EEPROM is at addresses 0x8100 - 0x82FF */

#define USER_EEPROM_BASE        0x8100

#define USER_EEPROM_SIZE        0x0200

#define USER_EEPROM_SLICES      32

​

/* MAX6875 commands */

#define MAX6875_CMD_BLK_READ        0x84

​

/* Each client has this additional data */

struct max6875_data {

    struct i2c_client   *fake_client;

    struct mutex        update_lock;

​

    u32         valid;

    u8          data[USER_EEPROM_SIZE];

    unsigned long       last_updated[USER_EEPROM_SLICES];

};

​

static void max6875_update_slice(struct i2c_client *client, int slice)

{

    struct max6875_data *data = i2c_get_clientdata(client);

    int i, j, addr;

    u8 *buf;

​

    if (slice >= USER_EEPROM_SLICES)

        return;

​

    mutex_lock(&data->update_lock);