linux/drivers/hwmon/lm70.c
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   1/*
   2 * lm70.c
   3 *
   4 * The LM70 is a temperature sensor chip from National Semiconductor (NS).
   5 * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com>
   6 *
   7 * The LM70 communicates with a host processor via an SPI/Microwire Bus
   8 * interface. The complete datasheet is available at National's website
   9 * here:
  10 * http://www.national.com/pf/LM/LM70.html
  11 *
  12 * This program is free software; you can redistribute it and/or modify
  13 * it under the terms of the GNU General Public License as published by
  14 * the Free Software Foundation; either version 2 of the License, or
  15 * (at your option) any later version.
  16 *
  17 * This program is distributed in the hope that it will be useful,
  18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 * GNU General Public License for more details.
  21 *
  22 * You should have received a copy of the GNU General Public License
  23 * along with this program; if not, write to the Free Software
  24 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  25 */
  26
  27#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  28
  29#include <linux/init.h>
  30#include <linux/module.h>
  31#include <linux/kernel.h>
  32#include <linux/device.h>
  33#include <linux/err.h>
  34#include <linux/sysfs.h>
  35#include <linux/hwmon.h>
  36#include <linux/mutex.h>
  37#include <linux/mod_devicetable.h>
  38#include <linux/spi/spi.h>
  39#include <linux/slab.h>
  40
  41
  42#define DRVNAME         "lm70"
  43
  44#define LM70_CHIP_LM70          0       /* original NS LM70 */
  45#define LM70_CHIP_TMP121        1       /* TI TMP121/TMP123 */
  46#define LM70_CHIP_LM71          2       /* NS LM71 */
  47#define LM70_CHIP_LM74          3       /* NS LM74 */
  48
  49struct lm70 {
  50        struct device *hwmon_dev;
  51        struct mutex lock;
  52        unsigned int chip;
  53};
  54
  55/* sysfs hook function */
  56static ssize_t lm70_sense_temp(struct device *dev,
  57                struct device_attribute *attr, char *buf)
  58{
  59        struct spi_device *spi = to_spi_device(dev);
  60        int status, val = 0;
  61        u8 rxbuf[2];
  62        s16 raw = 0;
  63        struct lm70 *p_lm70 = spi_get_drvdata(spi);
  64
  65        if (mutex_lock_interruptible(&p_lm70->lock))
  66                return -ERESTARTSYS;
  67
  68        /*
  69         * spi_read() requires a DMA-safe buffer; so we use
  70         * spi_write_then_read(), transmitting 0 bytes.
  71         */
  72        status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
  73        if (status < 0) {
  74                pr_warn("spi_write_then_read failed with status %d\n", status);
  75                goto out;
  76        }
  77        raw = (rxbuf[0] << 8) + rxbuf[1];
  78        dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
  79                rxbuf[0], rxbuf[1], raw);
  80
  81        /*
  82         * LM70:
  83         * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
  84         * complement value. Only the MSB 11 bits (1 sign + 10 temperature
  85         * bits) are meaningful; the LSB 5 bits are to be discarded.
  86         * See the datasheet.
  87         *
  88         * Further, each bit represents 0.25 degrees Celsius; so, multiply
  89         * by 0.25. Also multiply by 1000 to represent in millidegrees
  90         * Celsius.
  91         * So it's equivalent to multiplying by 0.25 * 1000 = 250.
  92         *
  93         * LM74 and TMP121/TMP123:
  94         * 13 bits of 2's complement data, discard LSB 3 bits,
  95         * resolution 0.0625 degrees celsius.
  96         *
  97         * LM71:
  98         * 14 bits of 2's complement data, discard LSB 2 bits,
  99         * resolution 0.0312 degrees celsius.
 100         */
 101        switch (p_lm70->chip) {
 102        case LM70_CHIP_LM70:
 103                val = ((int)raw / 32) * 250;
 104                break;
 105
 106        case LM70_CHIP_TMP121:
 107        case LM70_CHIP_LM74:
 108                val = ((int)raw / 8) * 625 / 10;
 109                break;
 110
 111        case LM70_CHIP_LM71:
 112                val = ((int)raw / 4) * 3125 / 100;
 113                break;
 114        }
 115
 116        status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
 117out:
 118        mutex_unlock(&p_lm70->lock);
 119        return status;
 120}
 121
 122static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL);
 123
 124static ssize_t lm70_show_name(struct device *dev, struct device_attribute
 125                              *devattr, char *buf)
 126{
 127        return sprintf(buf, "%s\n", to_spi_device(dev)->modalias);
 128}
 129
 130static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL);
 131
 132/*----------------------------------------------------------------------*/
 133
 134static int __devinit lm70_probe(struct spi_device *spi)
 135{
 136        int chip = spi_get_device_id(spi)->driver_data;
 137        struct lm70 *p_lm70;
 138        int status;
 139
 140        /* signaling is SPI_MODE_0 */
 141        if (spi->mode & (SPI_CPOL | SPI_CPHA))
 142                return -EINVAL;
 143
 144        /* NOTE:  we assume 8-bit words, and convert to 16 bits manually */
 145
 146        p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
 147        if (!p_lm70)
 148                return -ENOMEM;
 149
 150        mutex_init(&p_lm70->lock);
 151        p_lm70->chip = chip;
 152
 153        spi_set_drvdata(spi, p_lm70);
 154
 155        status = device_create_file(&spi->dev, &dev_attr_temp1_input);
 156        if (status)
 157                goto out_dev_create_temp_file_failed;
 158        status = device_create_file(&spi->dev, &dev_attr_name);
 159        if (status)
 160                goto out_dev_create_file_failed;
 161
 162        /* sysfs hook */
 163        p_lm70->hwmon_dev = hwmon_device_register(&spi->dev);
 164        if (IS_ERR(p_lm70->hwmon_dev)) {
 165                dev_dbg(&spi->dev, "hwmon_device_register failed.\n");
 166                status = PTR_ERR(p_lm70->hwmon_dev);
 167                goto out_dev_reg_failed;
 168        }
 169
 170        return 0;
 171
 172out_dev_reg_failed:
 173        device_remove_file(&spi->dev, &dev_attr_name);
 174out_dev_create_file_failed:
 175        device_remove_file(&spi->dev, &dev_attr_temp1_input);
 176out_dev_create_temp_file_failed:
 177        spi_set_drvdata(spi, NULL);
 178        return status;
 179}
 180
 181static int __devexit lm70_remove(struct spi_device *spi)
 182{
 183        struct lm70 *p_lm70 = spi_get_drvdata(spi);
 184
 185        hwmon_device_unregister(p_lm70->hwmon_dev);
 186        device_remove_file(&spi->dev, &dev_attr_temp1_input);
 187        device_remove_file(&spi->dev, &dev_attr_name);
 188        spi_set_drvdata(spi, NULL);
 189
 190        return 0;
 191}
 192
 193
 194static const struct spi_device_id lm70_ids[] = {
 195        { "lm70",   LM70_CHIP_LM70 },
 196        { "tmp121", LM70_CHIP_TMP121 },
 197        { "lm71",   LM70_CHIP_LM71 },
 198        { "lm74",   LM70_CHIP_LM74 },
 199        { },
 200};
 201MODULE_DEVICE_TABLE(spi, lm70_ids);
 202
 203static struct spi_driver lm70_driver = {
 204        .driver = {
 205                .name   = "lm70",
 206                .owner  = THIS_MODULE,
 207        },
 208        .id_table = lm70_ids,
 209        .probe  = lm70_probe,
 210        .remove = __devexit_p(lm70_remove),
 211};
 212
 213module_spi_driver(lm70_driver);
 214
 215MODULE_AUTHOR("Kaiwan N Billimoria");
 216MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
 217MODULE_LICENSE("GPL");
 218
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