drivers/hwmon/lm70.c

   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 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/kernel.h>
  30 #include <linux/device.h>
  31 #include <linux/err.h>
  32 #include <linux/sysfs.h>
  33 #include <linux/hwmon.h>
  34 #include <linux/mutex.h>
  35 #include <linux/mod_devicetable.h>
  36 #include <linux/spi/spi.h>
  37
  38
  39 #define DRVNAME         "lm70"
  40
  41 #define LM70_CHIP_LM70          0       /* original NS LM70 */
  42 #define LM70_CHIP_TMP121        1       /* TI TMP121/TMP123 */
  43
  44 struct lm70 {
  45         struct device *hwmon_dev;
  46         struct mutex lock;
  47         unsigned int chip;
  48 };
  49
  50 /* sysfs hook function */
  51 static ssize_t lm70_sense_temp(struct device *dev,
  52                 struct device_attribute *attr, char *buf)
  53 {
  54         struct spi_device *spi = to_spi_device(dev);
  55         int status, val = 0;
  56         u8 rxbuf[2];
  57         s16 raw=0;
  58         struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
  59
  60         if (mutex_lock_interruptible(&p_lm70->lock))
  61                 return -ERESTARTSYS;
  62
  63         /*
  64          * spi_read() requires a DMA-safe buffer; so we use
  65          * spi_write_then_read(), transmitting 0 bytes.
  66          */
  67         status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
  68         if (status < 0) {
  69                 printk(KERN_WARNING
  70                 "spi_write_then_read failed with status %d\n", status);
  71                 goto out;
  72         }
  73         raw = (rxbuf[0] << 8) + rxbuf[1];
  74         dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
  75                 rxbuf[0], rxbuf[1], raw);
  76
  77         /*
  78          * LM70:
  79          * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
  80          * complement value. Only the MSB 11 bits (1 sign + 10 temperature
  81          * bits) are meaningful; the LSB 5 bits are to be discarded.
  82          * See the datasheet.
  83          *
  84          * Further, each bit represents 0.25 degrees Celsius; so, multiply
  85          * by 0.25. Also multiply by 1000 to represent in millidegrees
  86          * Celsius.
  87          * So it's equivalent to multiplying by 0.25 * 1000 = 250.
  88          *
  89          * TMP121/TMP123:
  90          * 13 bits of 2's complement data, discard LSB 3 bits,
  91          * resolution 0.0625 degrees celsius.
  92          */
  93         switch (p_lm70->chip) {
  94         case LM70_CHIP_LM70:
  95                 val = ((int)raw / 32) * 250;
  96                 break;
  97
  98         case LM70_CHIP_TMP121:
  99                 val = ((int)raw / 8) * 625 / 10;
 100                 break;
 101         }
 102
 103         status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
 104 out:
 105         mutex_unlock(&p_lm70->lock);
 106         return status;
 107 }
 108
 109 static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL);
 110
 111 static ssize_t lm70_show_name(struct device *dev, struct device_attribute
 112                               *devattr, char *buf)
 113 {
 114         struct lm70 *p_lm70 = dev_get_drvdata(dev);
 115         int ret;
 116
 117         switch (p_lm70->chip) {
 118         case LM70_CHIP_LM70:
 119                 ret = sprintf(buf, "lm70\n");
 120                 break;
 121         case LM70_CHIP_TMP121:
 122                 ret = sprintf(buf, "tmp121\n");
 123                 break;
 124         default:
 125                 ret = -EINVAL;
 126         }
 127         return ret;
 128 }
 129
 130 static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL);
 131
 132 /*----------------------------------------------------------------------*/
 133
 134 static 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 for both LM70 and TMP121 */
 141         if (spi->mode & (SPI_CPOL | SPI_CPHA))
 142                 return -EINVAL;
 143
 144         /* 3-wire link (shared SI/SO) for LM70 */
 145         if (chip == LM70_CHIP_LM70 && !(spi->mode & SPI_3WIRE))
 146                 return -EINVAL;
 147
 148         /* NOTE:  we assume 8-bit words, and convert to 16 bits manually */
 149
 150         p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL);
 151         if (!p_lm70)
 152                 return -ENOMEM;
 153
 154         mutex_init(&p_lm70->lock);
 155         p_lm70->chip = chip;
 156
 157         /* sysfs hook */
 158         p_lm70->hwmon_dev = hwmon_device_register(&spi->dev);
 159         if (IS_ERR(p_lm70->hwmon_dev)) {
 160                 dev_dbg(&spi->dev, "hwmon_device_register failed.\n");
 161                 status = PTR_ERR(p_lm70->hwmon_dev);
 162                 goto out_dev_reg_failed;
 163         }
 164         dev_set_drvdata(&spi->dev, p_lm70);
 165
 166         if ((status = device_create_file(&spi->dev, &dev_attr_temp1_input))
 167          || (status = device_create_file(&spi->dev, &dev_attr_name))) {
 168                 dev_dbg(&spi->dev, "device_create_file failure.\n");
 169                 goto out_dev_create_file_failed;
 170         }
 171
 172         return 0;
 173
 174 out_dev_create_file_failed:
 175         device_remove_file(&spi->dev, &dev_attr_temp1_input);
 176         hwmon_device_unregister(p_lm70->hwmon_dev);
 177 out_dev_reg_failed:
 178         dev_set_drvdata(&spi->dev, NULL);
 179         kfree(p_lm70);
 180         return status;
 181 }
 182
 183 static int __devexit lm70_remove(struct spi_device *spi)
 184 {
 185         struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
 186
 187         device_remove_file(&spi->dev, &dev_attr_temp1_input);
 188         device_remove_file(&spi->dev, &dev_attr_name);
 189         hwmon_device_unregister(p_lm70->hwmon_dev);
 190         dev_set_drvdata(&spi->dev, NULL);
 191         kfree(p_lm70);
 192
 193         return 0;
 194 }
 195
 196
 197 static const struct spi_device_id lm70_ids[] = {
 198         { "lm70",   LM70_CHIP_LM70 },
 199         { "tmp121", LM70_CHIP_TMP121 },
 200         { },
 201 };
 202 MODULE_DEVICE_TABLE(spi, lm70_ids);
 203
 204 static struct spi_driver lm70_driver = {
 205         .driver = {
 206                 .name   = "lm70",
 207                 .owner  = THIS_MODULE,
 208         },
 209         .id_table = lm70_ids,
 210         .probe  = lm70_probe,
 211         .remove = __devexit_p(lm70_remove),
 212 };
 213
 214 static int __init init_lm70(void)
 215 {
 216         return spi_register_driver(&lm70_driver);
 217 }
 218
 219 static void __exit cleanup_lm70(void)
 220 {
 221         spi_unregister_driver(&lm70_driver);
 222 }
 223
 224 module_init(init_lm70);
 225 module_exit(cleanup_lm70);
 226
 227 MODULE_AUTHOR("Kaiwan N Billimoria");
 228 MODULE_DESCRIPTION("NS LM70 / TI TMP121/TMP123 Linux driver");
 229 MODULE_LICENSE("GPL");