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