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 #include <linux/slab.h>
  38
  39
  40 #define DRVNAME         "lm70"
  41
  42 #define LM70_CHIP_LM70          0       /* original NS LM70 */
  43 #define LM70_CHIP_TMP121        1       /* TI TMP121/TMP123 */
  44
  45 struct lm70 {
  46         struct device *hwmon_dev;
  47         struct mutex lock;
  48         unsigned int chip;
  49 };
  50
  51 /* sysfs hook function */
  52 static ssize_t lm70_sense_temp(struct device *dev,
  53                 struct device_attribute *attr, char *buf)
  54 {
  55         struct spi_device *spi = to_spi_device(dev);
  56         int status, val = 0;
  57         u8 rxbuf[2];
  58         s16 raw=0;
  59         struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
  60
  61         if (mutex_lock_interruptible(&p_lm70->lock))
  62                 return -ERESTARTSYS;
  63
  64         /*
  65          * spi_read() requires a DMA-safe buffer; so we use
  66          * spi_write_then_read(), transmitting 0 bytes.
  67          */
  68         status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
  69         if (status < 0) {
  70                 printk(KERN_WARNING
  71                 "spi_write_then_read failed with status %d\n", status);
  72                 goto out;
  73         }
  74         raw = (rxbuf[0] << 8) + rxbuf[1];
  75         dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
  76                 rxbuf[0], rxbuf[1], raw);
  77
  78         /*
  79          * LM70:
  80          * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
  81          * complement value. Only the MSB 11 bits (1 sign + 10 temperature
  82          * bits) are meaningful; the LSB 5 bits are to be discarded.
  83          * See the datasheet.
  84          *
  85          * Further, each bit represents 0.25 degrees Celsius; so, multiply
  86          * by 0.25. Also multiply by 1000 to represent in millidegrees
  87          * Celsius.
  88          * So it's equivalent to multiplying by 0.25 * 1000 = 250.
  89          *
  90          * TMP121/TMP123:
  91          * 13 bits of 2's complement data, discard LSB 3 bits,
  92          * resolution 0.0625 degrees celsius.
  93          */
  94         switch (p_lm70->chip) {
  95         case LM70_CHIP_LM70:
  96                 val = ((int)raw / 32) * 250;
  97                 break;
  98
  99         case LM70_CHIP_TMP121:
 100                 val = ((int)raw / 8) * 625 / 10;
 101                 break;
 102         }
 103
 104         status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
 105 out:
 106         mutex_unlock(&p_lm70->lock);
 107         return status;
 108 }
 109
 110 static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL);
 111
 112 static ssize_t lm70_show_name(struct device *dev, struct device_attribute
 113                               *devattr, char *buf)
 114 {
 115         struct lm70 *p_lm70 = dev_get_drvdata(dev);
 116         int ret;
 117
 118         switch (p_lm70->chip) {
 119         case LM70_CHIP_LM70:
 120                 ret = sprintf(buf, "lm70\n");
 121                 break;
 122         case LM70_CHIP_TMP121:
 123                 ret = sprintf(buf, "tmp121\n");
 124                 break;
 125         default:
 126                 ret = -EINVAL;
 127         }
 128         return ret;
 129 }
 130
 131 static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL);
 132
 133 /*----------------------------------------------------------------------*/
 134
 135 static int __devinit lm70_probe(struct spi_device *spi)
 136 {
 137         int chip = spi_get_device_id(spi)->driver_data;
 138         struct lm70 *p_lm70;
 139         int status;
 140
 141         /* signaling is SPI_MODE_0 for both LM70 and TMP121 */
 142         if (spi->mode & (SPI_CPOL | SPI_CPHA))
 143                 return -EINVAL;
 144
 145         /* 3-wire link (shared SI/SO) for LM70 */
 146         if (chip == LM70_CHIP_LM70 && !(spi->mode & SPI_3WIRE))
 147                 return -EINVAL;
 148
 149         /* NOTE:  we assume 8-bit words, and convert to 16 bits manually */
 150
 151         p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL);
 152         if (!p_lm70)
 153                 return -ENOMEM;
 154
 155         mutex_init(&p_lm70->lock);
 156         p_lm70->chip = chip;
 157
 158         /* sysfs hook */
 159         p_lm70->hwmon_dev = hwmon_device_register(&spi->dev);
 160         if (IS_ERR(p_lm70->hwmon_dev)) {
 161                 dev_dbg(&spi->dev, "hwmon_device_register failed.\n");
 162                 status = PTR_ERR(p_lm70->hwmon_dev);
 163                 goto out_dev_reg_failed;
 164         }
 165         dev_set_drvdata(&spi->dev, p_lm70);
 166
 167         if ((status = device_create_file(&spi->dev, &dev_attr_temp1_input))
 168          || (status = device_create_file(&spi->dev, &dev_attr_name))) {
 169                 dev_dbg(&spi->dev, "device_create_file failure.\n");
 170                 goto out_dev_create_file_failed;
 171         }
 172
 173         return 0;
 174
 175 out_dev_create_file_failed:
 176         device_remove_file(&spi->dev, &dev_attr_temp1_input);
 177         hwmon_device_unregister(p_lm70->hwmon_dev);
 178 out_dev_reg_failed:
 179         dev_set_drvdata(&spi->dev, NULL);
 180         kfree(p_lm70);
 181         return status;
 182 }
 183
 184 static int __devexit lm70_remove(struct spi_device *spi)
 185 {
 186         struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
 187
 188         device_remove_file(&spi->dev, &dev_attr_temp1_input);
 189         device_remove_file(&spi->dev, &dev_attr_name);
 190         hwmon_device_unregister(p_lm70->hwmon_dev);
 191         dev_set_drvdata(&spi->dev, NULL);
 192         kfree(p_lm70);
 193
 194         return 0;
 195 }
 196
 197
 198 static const struct spi_device_id lm70_ids[] = {
 199         { "lm70",   LM70_CHIP_LM70 },
 200         { "tmp121", LM70_CHIP_TMP121 },
 201         { },
 202 };
 203 MODULE_DEVICE_TABLE(spi, lm70_ids);
 204
 205 static struct spi_driver lm70_driver = {
 206         .driver = {
 207                 .name   = "lm70",
 208                 .owner  = THIS_MODULE,
 209         },
 210         .id_table = lm70_ids,
 211         .probe  = lm70_probe,
 212         .remove = __devexit_p(lm70_remove),
 213 };
 214
 215 static int __init init_lm70(void)
 216 {
 217         return spi_register_driver(&lm70_driver);
 218 }
 219
 220 static void __exit cleanup_lm70(void)
 221 {
 222         spi_unregister_driver(&lm70_driver);
 223 }
 224
 225 module_init(init_lm70);
 226 module_exit(cleanup_lm70);
 227
 228 MODULE_AUTHOR("Kaiwan N Billimoria");
 229 MODULE_DESCRIPTION("NS LM70 / TI TMP121/TMP123 Linux driver");
 230 MODULE_LICENSE("GPL");