ltc2978.c

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/*
 * Hardware monitoring driver for LTC2978 and LTC3880
 *
 * Copyright (c) 2011 Ericsson AB.
 *
 * 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 "pmbus.h"

enum chips { ltc2978, ltc3880 };

/* LTC2978 and LTC3880 */
#define LTC2978_MFR_VOUT_PEAK       0xdd
#define LTC2978_MFR_VIN_PEAK        0xde
#define LTC2978_MFR_TEMPERATURE_PEAK    0xdf
#define LTC2978_MFR_SPECIAL_ID      0xe7

/* LTC2978 only */
#define LTC2978_MFR_VOUT_MIN        0xfb
#define LTC2978_MFR_VIN_MIN     0xfc
#define LTC2978_MFR_TEMPERATURE_MIN 0xfd

/* LTC3880 only */
#define LTC3880_MFR_IOUT_PEAK       0xd7
#define LTC3880_MFR_CLEAR_PEAKS     0xe3
#define LTC3880_MFR_TEMPERATURE2_PEAK   0xf4

#define LTC2978_ID_REV1         0x0121
#define LTC2978_ID_REV2         0x0122
#define LTC3880_ID          0x4000
#define LTC3880_ID_MASK         0xff00

/*
 * LTC2978 clears peak data whenever the CLEAR_FAULTS command is executed, which
 * happens pretty much each time chip data is updated. Raw peak data therefore
 * does not provide much value. To be able to provide useful peak data, keep an
 * internal cache of measured peak data, which is only cleared if an explicit
 * "clear peak" command is executed for the sensor in question.
 */
struct ltc2978_data {
    enum chips id;
    int vin_min, vin_max;
    int temp_min, temp_max;
    int vout_min[8], vout_max[8];
    int iout_max[2];
    int temp2_max[2];
    struct pmbus_driver_info info;
};

#define to_ltc2978_data(x)  container_of(x, struct ltc2978_data, info)

static inline int lin11_to_val(int data)
{
    s16 e = ((s16)data) >> 11;
    s32 m = (((s16)(data << 5)) >> 5);

    /*
     * mantissa is 10 bit + sign, exponent adds up to 15 bit.
     * Add 6 bit to exponent for maximum accuracy (10 + 15 + 6 = 31).
     */
    e += 6;
    return (e < 0 ? m >> -e : m << e);
}

static int ltc2978_read_word_data_common(struct i2c_client *client, int page,
                     int reg)
{
    const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
    struct ltc2978_data *data = to_ltc2978_data(info);
    int ret;

    switch (reg) {
    case PMBUS_VIRT_READ_VIN_MAX:
        ret = pmbus_read_word_data(client, page, LTC2978_MFR_VIN_PEAK);
        if (ret >= 0) {
            if (lin11_to_val(ret) > lin11_to_val(data->vin_max))
                data->vin_max = ret;
            ret = data->vin_max;
        }
        break;
    case PMBUS_VIRT_READ_VOUT_MAX:
        ret = pmbus_read_word_data(client, page, LTC2978_MFR_VOUT_PEAK);
        if (ret >= 0) {
            /*
             * VOUT is 16 bit unsigned with fixed exponent,
             * so we can compare it directly
             */
            if (ret > data->vout_max[page])
                data->vout_max[page] = ret;
            ret = data->vout_max[page];
        }
        break;
    case PMBUS_VIRT_READ_TEMP_MAX:
        ret = pmbus_read_word_data(client, page,
                       LTC2978_MFR_TEMPERATURE_PEAK);
        if (ret >= 0) {
            if (lin11_to_val(ret) > lin11_to_val(data->temp_max))
                data->temp_max = ret;
            ret = data->temp_max;
        }
        break;
    case PMBUS_VIRT_RESET_VOUT_HISTORY:
    case PMBUS_VIRT_RESET_VIN_HISTORY:
    case PMBUS_VIRT_RESET_TEMP_HISTORY:
        ret = 0;
        break;
    default:
        ret = -ENODATA;
        break;
    }
    return ret;
}

static int ltc2978_read_word_data(struct i2c_client *client, int page, int reg)
{
    const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
    struct ltc2978_data *data = to_ltc2978_data(info);
    int ret;

    switch (reg) {
    case PMBUS_VIRT_READ_VIN_MIN:
        ret = pmbus_read_word_data(client, page, LTC2978_MFR_VIN_MIN);
        if (ret >= 0) {
            if (lin11_to_val(ret) < lin11_to_val(data->vin_min))
                data->vin_min = ret;
            ret = data->vin_min;
        }
        break;
    case PMBUS_VIRT_READ_VOUT_MIN:
        ret = pmbus_read_word_data(client, page, LTC2978_MFR_VOUT_MIN);
        if (ret >= 0) {
            /*
             * VOUT_MIN is known to not be supported on some lots
             * of LTC2978 revision 1, and will return the maximum
             * possible voltage if read. If VOUT_MAX is valid and
             * lower than the reading of VOUT_MIN, use it instead.
             */
            if (data->vout_max[page] && ret > data->vout_max[page])
                ret = data->vout_max[page];
            if (ret < data->vout_min[page])
                data->vout_min[page] = ret;
            ret = data->vout_min[page];
        }
        break;
    case PMBUS_VIRT_READ_TEMP_MIN:
        ret = pmbus_read_word_data(client, page,
                       LTC2978_MFR_TEMPERATURE_MIN);
        if (ret >= 0) {
            if (lin11_to_val(ret)
                < lin11_to_val(data->temp_min))
                data->temp_min = ret;
            ret = data->temp_min;
        }
        break;
    case PMBUS_VIRT_READ_IOUT_MAX:
    case PMBUS_VIRT_RESET_IOUT_HISTORY:
    case PMBUS_VIRT_READ_TEMP2_MAX:
    case PMBUS_VIRT_RESET_TEMP2_HISTORY:
        ret = -ENXIO;
        break;
    default:
        ret = ltc2978_read_word_data_common(client, page, reg);
        break;
    }
    return ret;
}

static int ltc3880_read_word_data(struct i2c_client *client, int page, int reg)
{
    const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
    struct ltc2978_data *data = to_ltc2978_data(info);
    int ret;

    switch (reg) {
    case PMBUS_VIRT_READ_IOUT_MAX:
        ret = pmbus_read_word_data(client, page, LTC3880_MFR_IOUT_PEAK);
        if (ret >= 0) {
            if (lin11_to_val(ret)
                > lin11_to_val(data->iout_max[page]))
                data->iout_max[page] = ret;
            ret = data->iout_max[page];
        }
        break;
    case PMBUS_VIRT_READ_TEMP2_MAX:
        ret = pmbus_read_word_data(client, page,
                       LTC3880_MFR_TEMPERATURE2_PEAK);
        if (ret >= 0) {
            if (lin11_to_val(ret)
                > lin11_to_val(data->temp2_max[page]))
                data->temp2_max[page] = ret;
            ret = data->temp2_max[page];
        }
        break;
    case PMBUS_VIRT_READ_VIN_MIN:
    case PMBUS_VIRT_READ_VOUT_MIN:
    case PMBUS_VIRT_READ_TEMP_MIN:
        ret = -ENXIO;
        break;
    case PMBUS_VIRT_RESET_IOUT_HISTORY:
    case PMBUS_VIRT_RESET_TEMP2_HISTORY:
        ret = 0;
        break;
    default:
        ret = ltc2978_read_word_data_common(client, page, reg);
        break;
    }
    return ret;
}

static int ltc2978_clear_peaks(struct i2c_client *client, int page,
                   enum chips id)
{
    int ret;

    if (id == ltc2978)
        ret = pmbus_write_byte(client, page, PMBUS_CLEAR_FAULTS);
    else
        ret = pmbus_write_byte(client, 0, LTC3880_MFR_CLEAR_PEAKS);

    return ret;
}

static int ltc2978_write_word_data(struct i2c_client *client, int page,
                    int reg, u16 word)
{
    const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
    struct ltc2978_data *data = to_ltc2978_data(info);
    int ret;

    switch (reg) {
    case PMBUS_VIRT_RESET_IOUT_HISTORY:
        data->iout_max[page] = 0x7fff;
        ret = ltc2978_clear_peaks(client, page, data->id);
        break;
    case PMBUS_VIRT_RESET_TEMP2_HISTORY:
        data->temp2_max[page] = 0x7fff;
        ret = ltc2978_clear_peaks(client, page, data->id);
        break;
    case PMBUS_VIRT_RESET_VOUT_HISTORY:
        data->vout_min[page] = 0xffff;
        data->vout_max[page] = 0;
        ret = ltc2978_clear_peaks(client, page, data->id);
        break;
    case PMBUS_VIRT_RESET_VIN_HISTORY:
        data->vin_min = 0x7bff;
        data->vin_max = 0;
        ret = ltc2978_clear_peaks(client, page, data->id);
        break;
    case PMBUS_VIRT_RESET_TEMP_HISTORY:
        data->temp_min = 0x7bff;
        data->temp_max = 0x7fff;
        ret = ltc2978_clear_peaks(client, page, data->id);
        break;
    default:
        ret = -ENODATA;
        break;
    }
    return ret;
}

static const struct i2c_device_id ltc2978_id[] = {
    {"ltc2978", ltc2978},
    {"ltc3880", ltc3880},
    {}
};
MODULE_DEVICE_TABLE(i2c, ltc2978_id);

static int ltc2978_probe(struct i2c_client *client,
             const struct i2c_device_id *id)
{
    int chip_id, i;
    struct ltc2978_data *data;
    struct pmbus_driver_info *info;

    if (!i2c_check_functionality(client->adapter,
                     I2C_FUNC_SMBUS_READ_WORD_DATA))
        return -ENODEV;

    data = devm_kzalloc(&client->dev, sizeof(struct ltc2978_data),
                GFP_KERNEL);
    if (!data)
        return -ENOMEM;

    chip_id = i2c_smbus_read_word_data(client, LTC2978_MFR_SPECIAL_ID);
    if (chip_id < 0)
        return chip_id;

    if (chip_id == LTC2978_ID_REV1 || chip_id == LTC2978_ID_REV2) {
        data->id = ltc2978;
    } else if ((chip_id & LTC3880_ID_MASK) == LTC3880_ID) {
        data->id = ltc3880;
    } else {
        dev_err(&client->dev, "Unsupported chip ID 0x%x\n", chip_id);
        return -ENODEV;
    }
    if (data->id != id->driver_data)
        dev_warn(&client->dev,
             "Device mismatch: Configured %s, detected %s\n",
             id->name,
             ltc2978_id[data->id].name);

    info = &data->info;
    info->write_word_data = ltc2978_write_word_data;

    data->vout_min[0] = 0xffff;
    data->vin_min = 0x7bff;
    data->temp_min = 0x7bff;
    data->temp_max = 0x7fff;

    switch (id->driver_data) {
    case ltc2978:
        info->read_word_data = ltc2978_read_word_data;
        info->pages = 8;
        info->func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_STATUS_INPUT
          | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
          | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP;
        for (i = 1; i < 8; i++) {
            info->func[i] = PMBUS_HAVE_VOUT
              | PMBUS_HAVE_STATUS_VOUT;
            data->vout_min[i] = 0xffff;
        }
        break;
    case ltc3880:
        info->read_word_data = ltc3880_read_word_data;
        info->pages = 2;
        info->func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN
          | PMBUS_HAVE_STATUS_INPUT
          | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
          | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT
          | PMBUS_HAVE_POUT | PMBUS_HAVE_TEMP
          | PMBUS_HAVE_TEMP2 | PMBUS_HAVE_STATUS_TEMP;
        info->func[1] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
          | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT
          | PMBUS_HAVE_POUT
          | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP;
        data->vout_min[1] = 0xffff;
        break;
    default:
        return -ENODEV;
    }

    return pmbus_do_probe(client, id, info);
}

/* This is the driver that will be inserted */
static struct i2c_driver ltc2978_driver = {
    .driver = {
           .name = "ltc2978",
           },
    .probe = ltc2978_probe,
    .remove = pmbus_do_remove,
    .id_table = ltc2978_id,
};

module_i2c_driver(ltc2978_driver);

MODULE_AUTHOR("Guenter Roeck");
MODULE_DESCRIPTION("PMBus driver for LTC2978 and LTC3880");
MODULE_LICENSE("GPL");