linux-imx

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

/*

 * Driver for Linear Technology LTC4215 I2C Hot Swap Controller

 *

 * Copyright (C) 2009 Ira W. Snyder <iws@ovro.caltech.edu>

 *

 * Datasheet:

 * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1163,P17572,D12697

 */

​

#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>

​

/* Here are names of the chip's registers (a.k.a. commands) */

enum ltc4215_cmd {

    LTC4215_CONTROL         = 0x00, /* rw */

    LTC4215_ALERT           = 0x01, /* rw */

    LTC4215_STATUS          = 0x02, /* ro */

    LTC4215_FAULT           = 0x03, /* rw */

    LTC4215_SENSE           = 0x04, /* rw */

    LTC4215_SOURCE          = 0x05, /* rw */

    LTC4215_ADIN            = 0x06, /* rw */

};

​

struct ltc4215_data {

    struct i2c_client *client;

​

    struct mutex update_lock;

    bool valid;

    unsigned long last_updated; /* in jiffies */

​

    /* Registers */

    u8 regs[7];

};

​

static struct ltc4215_data *ltc4215_update_device(struct device *dev)

{

    struct ltc4215_data *data = dev_get_drvdata(dev);

    struct i2c_client *client = data->client;

    s32 val;

    int i;

​

    mutex_lock(&data->update_lock);

​

    /* The chip's A/D updates 10 times per second */

    if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) {

​

        dev_dbg(&client->dev, "Starting ltc4215 update\n");

​

        /* Read all registers */

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

            val = i2c_smbus_read_byte_data(client, i);

            if (unlikely(val < 0))

                data->regs[i] = 0;

            else

                data->regs[i] = val;

        }

​

        data->last_updated = jiffies;

        data->valid = 1;

    }

​

    mutex_unlock(&data->update_lock);

​

    return data;

}

​

/* Return the voltage from the given register in millivolts */

static int ltc4215_get_voltage(struct device *dev, u8 reg)

{

    struct ltc4215_data *data = ltc4215_update_device(dev);

    const u8 regval = data->regs[reg];

    u32 voltage = 0;

​

    switch (reg) {

    case LTC4215_SENSE:

        /* 151 uV per increment */

        voltage = regval * 151 / 1000;

        break;

    case LTC4215_SOURCE:

        /* 60.5 mV per increment */

        voltage = regval * 605 / 10;

        break;

    case LTC4215_ADIN:

        /*