linux-imx

// SPDX-License-Identifier: GPL-2.0-or-later

/*

 * Copyright (C) 1998, 1999  Frodo Looijaard <frodol@dds.nl> and

 *                           Philip Edelbrock <phil@netroedge.com>

 * Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>

 * Copyright (C) 2003 IBM Corp.

 * Copyright (C) 2004 Jean Delvare <jdelvare@suse.de>

 */

​

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/device.h>

#include <linux/capability.h>

#include <linux/jiffies.h>

#include <linux/i2c.h>

#include <linux/mutex.h>

​

/* Addresses to scan */

static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,

                    0x55, 0x56, 0x57, I2C_CLIENT_END };

​

​

/* Size of EEPROM in bytes */

#define EEPROM_SIZE     256

​

/* possible types of eeprom devices */

enum eeprom_nature {

    UNKNOWN,

    VAIO,

};

​

/* Each client has this additional data */

struct eeprom_data {

    struct mutex update_lock;

    u8 valid;           /* bitfield, bit!=0 if slice is valid */

    unsigned long last_updated[8];  /* In jiffies, 8 slices */

    u8 data[EEPROM_SIZE];       /* Register values */

    enum eeprom_nature nature;

};

​

​

static void eeprom_update_client(struct i2c_client *client, u8 slice)

{

    struct eeprom_data *data = i2c_get_clientdata(client);

    int i;

​

    mutex_lock(&data->update_lock);

​

    if (!(data->valid & (1 << slice)) ||

        time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {

        dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);

​

        if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {

            for (i = slice << 5; i < (slice + 1) << 5; i += 32)

                if (i2c_smbus_read_i2c_block_data(client, i,

                            32, data->data + i)

                            != 32)

                    goto exit;

        } else {

            for (i = slice << 5; i < (slice + 1) << 5; i += 2) {

                int word = i2c_smbus_read_word_data(client, i);

                if (word < 0)

                    goto exit;

                data->data[i] = word & 0xff;

                data->data[i + 1] = word >> 8;

            }

        }

        data->last_updated[slice] = jiffies;

        data->valid |= (1 << slice);

    }

exit:

    mutex_unlock(&data->update_lock);

}

​

static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,

               struct bin_attribute *bin_attr,

               char *buf, loff_t off, size_t count)

{

    struct i2c_client *client = to_i2c_client(kobj_to_dev(kobj));

    struct eeprom_data *data = i2c_get_clientdata(client);

    u8 slice;

​

    /* Only refresh slices which contain requested bytes */

    for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)

        eeprom_update_client(client, slice);

​

    /* Hide Vaio private settings to regular users:

       - BIOS passwords: bytes 0x00 to 0x0f

       - UUID: bytes 0x10 to 0x1f

       - Serial number: 0xc0 to 0xdf */

    if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {

        int i;