linux-imx

/*

 * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller

 *

 * Copyright (C) 2010 Ericsson AB.

 *

 * Derived from:

 *

 *  Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller

 *  Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>

 *

 * Datasheet: http://cds.linear.com/docs/Datasheet/42612fb.pdf

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 */

​

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/err.h>

#include <linux/slab.h>

#include <linux/i2c.h>

#include <linux/hwmon.h>

#include <linux/hwmon-sysfs.h>

#include <linux/jiffies.h>

​

/* chip registers */

#define LTC4261_STATUS  0x00    /* readonly */

#define LTC4261_FAULT   0x01

#define LTC4261_ALERT   0x02

#define LTC4261_CONTROL 0x03

#define LTC4261_SENSE_H 0x04

#define LTC4261_SENSE_L 0x05

#define LTC4261_ADIN2_H 0x06

#define LTC4261_ADIN2_L 0x07

#define LTC4261_ADIN_H  0x08

#define LTC4261_ADIN_L  0x09

​

/*

 * Fault register bits

 */

#define FAULT_OV    (1<<0)

#define FAULT_UV    (1<<1)

#define FAULT_OC    (1<<2)

​

struct ltc4261_data {

    struct i2c_client *client;

​

    struct mutex update_lock;

    bool valid;

    unsigned long last_updated; /* in jiffies */

​

    /* Registers */

    u8 regs[10];

};

​

static struct ltc4261_data *ltc4261_update_device(struct device *dev)

{

    struct ltc4261_data *data = dev_get_drvdata(dev);

    struct i2c_client *client = data->client;

    struct ltc4261_data *ret = data;

​

    mutex_lock(&data->update_lock);

​

    if (time_after(jiffies, data->last_updated + HZ / 4) || !data->valid) {

        int i;

​

        /* Read registers -- 0x00 to 0x09 */

        for (i = 0; i < ARRAY_SIZE(data->regs); i++) {

            int val;

​

            val = i2c_smbus_read_byte_data(client, i);

            if (unlikely(val < 0)) {

                dev_dbg(dev,

                    "Failed to read ADC value: error %d\n",

                    val);

                ret = ERR_PTR(val);

                data->valid = 0;

                goto abort;

            }

            data->regs[i] = val;