ltc4245.c

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/*
 * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
 *
 * Copyright (C) 2008 Ira W. Snyder <[email protected]>
 *
 * 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; version 2 of the License.
 *
 * This driver is based on the ds1621 and ina209 drivers.
 *
 * Datasheet:
 * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517
 */

#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>
#include <linux/i2c/ltc4245.h>

/* Here are names of the chip's registers (a.k.a. commands) */
enum ltc4245_cmd {
    LTC4245_STATUS          = 0x00, /* readonly */
    LTC4245_ALERT           = 0x01,
    LTC4245_CONTROL         = 0x02,
    LTC4245_ON          = 0x03,
    LTC4245_FAULT1          = 0x04,
    LTC4245_FAULT2          = 0x05,
    LTC4245_GPIO            = 0x06,
    LTC4245_ADCADR          = 0x07,

    LTC4245_12VIN           = 0x10,
    LTC4245_12VSENSE        = 0x11,
    LTC4245_12VOUT          = 0x12,
    LTC4245_5VIN            = 0x13,
    LTC4245_5VSENSE         = 0x14,
    LTC4245_5VOUT           = 0x15,
    LTC4245_3VIN            = 0x16,
    LTC4245_3VSENSE         = 0x17,
    LTC4245_3VOUT           = 0x18,
    LTC4245_VEEIN           = 0x19,
    LTC4245_VEESENSE        = 0x1a,
    LTC4245_VEEOUT          = 0x1b,
    LTC4245_GPIOADC         = 0x1c,
};

struct ltc4245_data {
    struct device *hwmon_dev;

    struct mutex update_lock;
    bool valid;
    unsigned long last_updated; /* in jiffies */

    /* Control registers */
    u8 cregs[0x08];

    /* Voltage registers */
    u8 vregs[0x0d];

    /* GPIO ADC registers */
    bool use_extra_gpios;
    int gpios[3];
};

/*
 * Update the readings from the GPIO pins. If the driver has been configured to
 * sample all GPIO's as analog voltages, a round-robin sampling method is used.
 * Otherwise, only the configured GPIO pin is sampled.
 *
 * LOCKING: must hold data->update_lock
 */
static void ltc4245_update_gpios(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct ltc4245_data *data = i2c_get_clientdata(client);
    u8 gpio_curr, gpio_next, gpio_reg;
    int i;

    /* no extra gpio support, we're basically done */
    if (!data->use_extra_gpios) {
        data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10];
        return;
    }

    /*
     * If the last reading was too long ago, then we mark all old GPIO
     * readings as stale by setting them to -EAGAIN
     */
    if (time_after(jiffies, data->last_updated + 5 * HZ)) {
        dev_dbg(&client->dev, "Marking GPIOs invalid\n");
        for (i = 0; i < ARRAY_SIZE(data->gpios); i++)
            data->gpios[i] = -EAGAIN;
    }

    /*
     * Get the current GPIO pin
     *
     * The datasheet calls these GPIO[1-3], but we'll calculate the zero
     * based array index instead, and call them GPIO[0-2]. This is much
     * easier to think about.
     */
    gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6;
    if (gpio_curr > 0)
        gpio_curr -= 1;

    /* Read the GPIO voltage from the GPIOADC register */
    data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10];

    /* Find the next GPIO pin to read */
    gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios);

    /*
     * Calculate the correct setting for the GPIO register so it will
     * sample the next GPIO pin
     */
    gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6);

    /* Update the GPIO register */
    i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg);

    /* Update saved data */
    data->cregs[LTC4245_GPIO] = gpio_reg;
}

static struct ltc4245_data *ltc4245_update_device(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct ltc4245_data *data = i2c_get_clientdata(client);
    s32 val;
    int i;

    mutex_lock(&data->update_lock);

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

        dev_dbg(&client->dev, "Starting ltc4245 update\n");

        /* Read control registers -- 0x00 to 0x07 */
        for (i = 0; i < ARRAY_SIZE(data->cregs); i++) {
            val = i2c_smbus_read_byte_data(client, i);
            if (unlikely(val < 0))
                data->cregs[i] = 0;
            else
                data->cregs[i] = val;
        }

        /* Read voltage registers -- 0x10 to 0x1c */
        for (i = 0; i < ARRAY_SIZE(data->vregs); i++) {
            val = i2c_smbus_read_byte_data(client, i+0x10);
            if (unlikely(val < 0))
                data->vregs[i] = 0;
            else
                data->vregs[i] = val;
        }

        /* Update GPIO readings */
        ltc4245_update_gpios(dev);

        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 ltc4245_get_voltage(struct device *dev, u8 reg)
{
    struct ltc4245_data *data = ltc4245_update_device(dev);
    const u8 regval = data->vregs[reg - 0x10];
    u32 voltage = 0;

    switch (reg) {
    case LTC4245_12VIN:
    case LTC4245_12VOUT:
        voltage = regval * 55;
        break;
    case LTC4245_5VIN:
    case LTC4245_5VOUT:
        voltage = regval * 22;
        break;
    case LTC4245_3VIN:
    case LTC4245_3VOUT:
        voltage = regval * 15;
        break;
    case LTC4245_VEEIN:
    case LTC4245_VEEOUT:
        voltage = regval * -55;
        break;
    case LTC4245_GPIOADC:
        voltage = regval * 10;
        break;
    default:
        /* If we get here, the developer messed up */
        WARN_ON_ONCE(1);
        break;
    }

    return voltage;
}

/* Return the current in the given sense register in milliAmperes */
static unsigned int ltc4245_get_current(struct device *dev, u8 reg)
{
    struct ltc4245_data *data = ltc4245_update_device(dev);
    const u8 regval = data->vregs[reg - 0x10];
    unsigned int voltage;
    unsigned int curr;

    /*
     * The strange looking conversions that follow are fixed-point
     * math, since we cannot do floating point in the kernel.
     *
     * Step 1: convert sense register to microVolts
     * Step 2: convert voltage to milliAmperes
     *
     * If you play around with the V=IR equation, you come up with
     * the following: X uV / Y mOhm == Z mA
     *
     * With the resistors that are fractions of a milliOhm, we multiply
     * the voltage and resistance by 10, to shift the decimal point.
     * Now we can use the normal division operator again.
     */

    switch (reg) {
    case LTC4245_12VSENSE:
        voltage = regval * 250; /* voltage in uV */
        curr = voltage / 50; /* sense resistor 50 mOhm */
        break;
    case LTC4245_5VSENSE:
        voltage = regval * 125; /* voltage in uV */
        curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */
        break;
    case LTC4245_3VSENSE:
        voltage = regval * 125; /* voltage in uV */
        curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */
        break;
    case LTC4245_VEESENSE:
        voltage = regval * 250; /* voltage in uV */
        curr = voltage / 100; /* sense resistor 100 mOhm */
        break;
    default:
        /* If we get here, the developer messed up */
        WARN_ON_ONCE(1);
        curr = 0;
        break;
    }

    return curr;
}

static ssize_t ltc4245_show_voltage(struct device *dev,
                    struct device_attribute *da,
                    char *buf)
{
    struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
    const int voltage = ltc4245_get_voltage(dev, attr->index);

    return snprintf(buf, PAGE_SIZE, "%d\n", voltage);
}

static ssize_t ltc4245_show_current(struct device *dev,
                    struct device_attribute *da,
                    char *buf)
{
    struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
    const unsigned int curr = ltc4245_get_current(dev, attr->index);

    return snprintf(buf, PAGE_SIZE, "%u\n", curr);
}

static ssize_t ltc4245_show_power(struct device *dev,
                  struct device_attribute *da,
                  char *buf)
{
    struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
    const unsigned int curr = ltc4245_get_current(dev, attr->index);
    const int output_voltage = ltc4245_get_voltage(dev, attr->index+1);

    /* current in mA * voltage in mV == power in uW */
    const unsigned int power = abs(output_voltage * curr);

    return snprintf(buf, PAGE_SIZE, "%u\n", power);
}

static ssize_t ltc4245_show_alarm(struct device *dev,
                      struct device_attribute *da,
                      char *buf)
{
    struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
    struct ltc4245_data *data = ltc4245_update_device(dev);
    const u8 reg = data->cregs[attr->index];
    const u32 mask = attr->nr;

    return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0);
}

static ssize_t ltc4245_show_gpio(struct device *dev,
                 struct device_attribute *da,
                 char *buf)
{
    struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
    struct ltc4245_data *data = ltc4245_update_device(dev);
    int val = data->gpios[attr->index];

    /* handle stale GPIO's */
    if (val < 0)
        return val;

    /* Convert to millivolts and print */
    return snprintf(buf, PAGE_SIZE, "%u\n", val * 10);
}

/*
 * These macros are used below in constructing device attribute objects
 * for use with sysfs_create_group() to make a sysfs device file
 * for each register.
 */

#define LTC4245_VOLTAGE(name, ltc4245_cmd_idx) \
    static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
    ltc4245_show_voltage, NULL, ltc4245_cmd_idx)

#define LTC4245_CURRENT(name, ltc4245_cmd_idx) \
    static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
    ltc4245_show_current, NULL, ltc4245_cmd_idx)

#define LTC4245_POWER(name, ltc4245_cmd_idx) \
    static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
    ltc4245_show_power, NULL, ltc4245_cmd_idx)

#define LTC4245_ALARM(name, mask, reg) \
    static SENSOR_DEVICE_ATTR_2(name, S_IRUGO, \
    ltc4245_show_alarm, NULL, (mask), reg)

#define LTC4245_GPIO_VOLTAGE(name, gpio_num) \
    static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
    ltc4245_show_gpio, NULL, gpio_num)

/* Construct a sensor_device_attribute structure for each register */

/* Input voltages */
LTC4245_VOLTAGE(in1_input,          LTC4245_12VIN);
LTC4245_VOLTAGE(in2_input,          LTC4245_5VIN);
LTC4245_VOLTAGE(in3_input,          LTC4245_3VIN);
LTC4245_VOLTAGE(in4_input,          LTC4245_VEEIN);

/* Input undervoltage alarms */
LTC4245_ALARM(in1_min_alarm,    (1 << 0),   LTC4245_FAULT1);
LTC4245_ALARM(in2_min_alarm,    (1 << 1),   LTC4245_FAULT1);
LTC4245_ALARM(in3_min_alarm,    (1 << 2),   LTC4245_FAULT1);
LTC4245_ALARM(in4_min_alarm,    (1 << 3),   LTC4245_FAULT1);

/* Currents (via sense resistor) */
LTC4245_CURRENT(curr1_input,            LTC4245_12VSENSE);
LTC4245_CURRENT(curr2_input,            LTC4245_5VSENSE);
LTC4245_CURRENT(curr3_input,            LTC4245_3VSENSE);
LTC4245_CURRENT(curr4_input,            LTC4245_VEESENSE);

/* Overcurrent alarms */
LTC4245_ALARM(curr1_max_alarm,  (1 << 4),   LTC4245_FAULT1);
LTC4245_ALARM(curr2_max_alarm,  (1 << 5),   LTC4245_FAULT1);
LTC4245_ALARM(curr3_max_alarm,  (1 << 6),   LTC4245_FAULT1);
LTC4245_ALARM(curr4_max_alarm,  (1 << 7),   LTC4245_FAULT1);

/* Output voltages */
LTC4245_VOLTAGE(in5_input,          LTC4245_12VOUT);
LTC4245_VOLTAGE(in6_input,          LTC4245_5VOUT);
LTC4245_VOLTAGE(in7_input,          LTC4245_3VOUT);
LTC4245_VOLTAGE(in8_input,          LTC4245_VEEOUT);

/* Power Bad alarms */
LTC4245_ALARM(in5_min_alarm,    (1 << 0),   LTC4245_FAULT2);
LTC4245_ALARM(in6_min_alarm,    (1 << 1),   LTC4245_FAULT2);
LTC4245_ALARM(in7_min_alarm,    (1 << 2),   LTC4245_FAULT2);
LTC4245_ALARM(in8_min_alarm,    (1 << 3),   LTC4245_FAULT2);

/* GPIO voltages */
LTC4245_GPIO_VOLTAGE(in9_input,         0);
LTC4245_GPIO_VOLTAGE(in10_input,        1);
LTC4245_GPIO_VOLTAGE(in11_input,        2);

/* Power Consumption (virtual) */
LTC4245_POWER(power1_input,         LTC4245_12VSENSE);
LTC4245_POWER(power2_input,         LTC4245_5VSENSE);
LTC4245_POWER(power3_input,         LTC4245_3VSENSE);
LTC4245_POWER(power4_input,         LTC4245_VEESENSE);

/*
 * Finally, construct an array of pointers to members of the above objects,
 * as required for sysfs_create_group()
 */
static struct attribute *ltc4245_std_attributes[] = {
    &sensor_dev_attr_in1_input.dev_attr.attr,
    &sensor_dev_attr_in2_input.dev_attr.attr,
    &sensor_dev_attr_in3_input.dev_attr.attr,
    &sensor_dev_attr_in4_input.dev_attr.attr,

    &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
    &sensor_dev_attr_in2_min_alarm.dev_attr.attr,
    &sensor_dev_attr_in3_min_alarm.dev_attr.attr,
    &sensor_dev_attr_in4_min_alarm.dev_attr.attr,

    &sensor_dev_attr_curr1_input.dev_attr.attr,
    &sensor_dev_attr_curr2_input.dev_attr.attr,
    &sensor_dev_attr_curr3_input.dev_attr.attr,
    &sensor_dev_attr_curr4_input.dev_attr.attr,

    &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
    &sensor_dev_attr_curr2_max_alarm.dev_attr.attr,
    &sensor_dev_attr_curr3_max_alarm.dev_attr.attr,
    &sensor_dev_attr_curr4_max_alarm.dev_attr.attr,

    &sensor_dev_attr_in5_input.dev_attr.attr,
    &sensor_dev_attr_in6_input.dev_attr.attr,
    &sensor_dev_attr_in7_input.dev_attr.attr,
    &sensor_dev_attr_in8_input.dev_attr.attr,

    &sensor_dev_attr_in5_min_alarm.dev_attr.attr,
    &sensor_dev_attr_in6_min_alarm.dev_attr.attr,
    &sensor_dev_attr_in7_min_alarm.dev_attr.attr,
    &sensor_dev_attr_in8_min_alarm.dev_attr.attr,

    &sensor_dev_attr_in9_input.dev_attr.attr,

    &sensor_dev_attr_power1_input.dev_attr.attr,
    &sensor_dev_attr_power2_input.dev_attr.attr,
    &sensor_dev_attr_power3_input.dev_attr.attr,
    &sensor_dev_attr_power4_input.dev_attr.attr,

    NULL,
};

static struct attribute *ltc4245_gpio_attributes[] = {
    &sensor_dev_attr_in10_input.dev_attr.attr,
    &sensor_dev_attr_in11_input.dev_attr.attr,
    NULL,
};

static const struct attribute_group ltc4245_std_group = {
    .attrs = ltc4245_std_attributes,
};

static const struct attribute_group ltc4245_gpio_group = {
    .attrs = ltc4245_gpio_attributes,
};

static int ltc4245_sysfs_create_groups(struct i2c_client *client)
{
    struct ltc4245_data *data = i2c_get_clientdata(client);
    struct device *dev = &client->dev;
    int ret;

    /* register the standard sysfs attributes */
    ret = sysfs_create_group(&dev->kobj, &ltc4245_std_group);
    if (ret) {
        dev_err(dev, "unable to register standard attributes\n");
        return ret;
    }

    /* if we're using the extra gpio support, register it's attributes */
    if (data->use_extra_gpios) {
        ret = sysfs_create_group(&dev->kobj, &ltc4245_gpio_group);
        if (ret) {
            dev_err(dev, "unable to register gpio attributes\n");
            sysfs_remove_group(&dev->kobj, &ltc4245_std_group);
            return ret;
        }
    }

    return 0;
}

static void ltc4245_sysfs_remove_groups(struct i2c_client *client)
{
    struct ltc4245_data *data = i2c_get_clientdata(client);
    struct device *dev = &client->dev;

    if (data->use_extra_gpios)
        sysfs_remove_group(&dev->kobj, &ltc4245_gpio_group);

    sysfs_remove_group(&dev->kobj, &ltc4245_std_group);
}

static bool ltc4245_use_extra_gpios(struct i2c_client *client)
{
    struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev);
#ifdef CONFIG_OF
    struct device_node *np = client->dev.of_node;
#endif

    /* prefer platform data */
    if (pdata)
        return pdata->use_extra_gpios;

#ifdef CONFIG_OF
    /* fallback on OF */
    if (of_find_property(np, "ltc4245,use-extra-gpios", NULL))
        return true;
#endif

    return false;
}

static int ltc4245_probe(struct i2c_client *client,
             const struct i2c_device_id *id)
{
    struct i2c_adapter *adapter = client->adapter;
    struct ltc4245_data *data;
    int ret;

    if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
        return -ENODEV;

    data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
    if (!data)
        return -ENOMEM;

    i2c_set_clientdata(client, data);
    mutex_init(&data->update_lock);
    data->use_extra_gpios = ltc4245_use_extra_gpios(client);

    /* Initialize the LTC4245 chip */
    i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00);
    i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00);

    /* Register sysfs hooks */
    ret = ltc4245_sysfs_create_groups(client);
    if (ret)
        return ret;

    data->hwmon_dev = hwmon_device_register(&client->dev);
    if (IS_ERR(data->hwmon_dev)) {
        ret = PTR_ERR(data->hwmon_dev);
        goto out_hwmon_device_register;
    }

    return 0;

out_hwmon_device_register:
    ltc4245_sysfs_remove_groups(client);
    return ret;
}

static int ltc4245_remove(struct i2c_client *client)
{
    struct ltc4245_data *data = i2c_get_clientdata(client);

    hwmon_device_unregister(data->hwmon_dev);
    ltc4245_sysfs_remove_groups(client);

    return 0;
}

static const struct i2c_device_id ltc4245_id[] = {
    { "ltc4245", 0 },
    { }
};
MODULE_DEVICE_TABLE(i2c, ltc4245_id);

/* This is the driver that will be inserted */
static struct i2c_driver ltc4245_driver = {
    .driver = {
        .name   = "ltc4245",
    },
    .probe      = ltc4245_probe,
    .remove     = ltc4245_remove,
    .id_table   = ltc4245_id,
};

module_i2c_driver(ltc4245_driver);

MODULE_AUTHOR("Ira W. Snyder <[email protected]>");
MODULE_DESCRIPTION("LTC4245 driver");
MODULE_LICENSE("GPL");