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 #include <linux/of_device.h>
  41
  42
  43 #define DRVNAME         "lm70"
  44
  45 #define LM70_CHIP_LM70          0       /* original NS LM70 */
  46 #define LM70_CHIP_TMP121        1       /* TI TMP121/TMP123 */
  47 #define LM70_CHIP_LM71          2       /* NS LM71 */
  48 #define LM70_CHIP_LM74          3       /* NS LM74 */
  49 #define LM70_CHIP_TMP122        4       /* TI TMP122/TMP124 */
  50
  51 struct lm70 {
  52         struct spi_device *spi;
  53         struct mutex lock;
  54         unsigned int chip;
  55 };
  56
  57 /* sysfs hook function */
  58 static ssize_t temp1_input_show(struct device *dev,
  59                                 struct device_attribute *attr, char *buf)
  60 {
  61         struct lm70 *p_lm70 = dev_get_drvdata(dev);
  62         struct spi_device *spi = p_lm70->spi;
  63         int status, val = 0;
  64         u8 rxbuf[2];
  65         s16 raw = 0;
  66
  67         if (mutex_lock_interruptible(&p_lm70->lock))
  68                 return -ERESTARTSYS;
  69
  70         /*
  71          * spi_read() requires a DMA-safe buffer; so we use
  72          * spi_write_then_read(), transmitting 0 bytes.
  73          */
  74         status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
  75         if (status < 0) {
  76                 dev_warn(dev, "spi_write_then_read failed with status %d\n",
  77                          status);
  78                 goto out;
  79         }
  80         raw = (rxbuf[0] << 8) + rxbuf[1];
  81         dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
  82                 rxbuf[0], rxbuf[1], raw);
  83
  84         /*
  85          * LM70:
  86          * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
  87          * complement value. Only the MSB 11 bits (1 sign + 10 temperature
  88          * bits) are meaningful; the LSB 5 bits are to be discarded.
  89          * See the datasheet.
  90          *
  91          * Further, each bit represents 0.25 degrees Celsius; so, multiply
  92          * by 0.25. Also multiply by 1000 to represent in millidegrees
  93          * Celsius.
  94          * So it's equivalent to multiplying by 0.25 * 1000 = 250.
  95          *
  96          * LM74 and TMP121/TMP122/TMP123/TMP124:
  97          * 13 bits of 2's complement data, discard LSB 3 bits,
  98          * resolution 0.0625 degrees celsius.
  99          *
 100          * LM71:
 101          * 14 bits of 2's complement data, discard LSB 2 bits,
 102          * resolution 0.0312 degrees celsius.
 103          */
 104         switch (p_lm70->chip) {
 105         case LM70_CHIP_LM70:
 106                 val = ((int)raw / 32) * 250;
 107                 break;
 108
 109         case LM70_CHIP_TMP121:
 110         case LM70_CHIP_TMP122:
 111         case LM70_CHIP_LM74:
 112                 val = ((int)raw / 8) * 625 / 10;
 113                 break;
 114
 115         case LM70_CHIP_LM71:
 116                 val = ((int)raw / 4) * 3125 / 100;
 117                 break;
 118         }
 119
 120         status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
 121 out:
 122         mutex_unlock(&p_lm70->lock);
 123         return status;
 124 }
 125
 126 static DEVICE_ATTR_RO(temp1_input);
 127
 128 static struct attribute *lm70_attrs[] = {
 129         &dev_attr_temp1_input.attr,
 130         NULL
 131 };
 132
 133 ATTRIBUTE_GROUPS(lm70);
 134
 135 /*----------------------------------------------------------------------*/
 136
 137 #ifdef CONFIG_OF
 138 static const struct of_device_id lm70_of_ids[] = {
 139         {
 140                 .compatible = "ti,lm70",
 141                 .data = (void *) LM70_CHIP_LM70,
 142         },
 143         {
 144                 .compatible = "ti,tmp121",
 145                 .data = (void *) LM70_CHIP_TMP121,
 146         },
 147         {
 148                 .compatible = "ti,tmp122",
 149                 .data = (void *) LM70_CHIP_TMP122,
 150         },
 151         {
 152                 .compatible = "ti,lm71",
 153                 .data = (void *) LM70_CHIP_LM71,
 154         },
 155         {
 156                 .compatible = "ti,lm74",
 157                 .data = (void *) LM70_CHIP_LM74,
 158         },
 159         {},
 160 };
 161 MODULE_DEVICE_TABLE(of, lm70_of_ids);
 162 #endif
 163
 164 static int lm70_probe(struct spi_device *spi)
 165 {
 166         const struct of_device_id *match;
 167         struct device *hwmon_dev;
 168         struct lm70 *p_lm70;
 169         int chip;
 170
 171         match = of_match_device(lm70_of_ids, &spi->dev);
 172         if (match)
 173                 chip = (int)(uintptr_t)match->data;
 174         else
 175                 chip = spi_get_device_id(spi)->driver_data;
 176
 177         /* signaling is SPI_MODE_0 */
 178         if (spi->mode & (SPI_CPOL | SPI_CPHA))
 179                 return -EINVAL;
 180
 181         /* NOTE:  we assume 8-bit words, and convert to 16 bits manually */
 182
 183         p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
 184         if (!p_lm70)
 185                 return -ENOMEM;
 186
 187         mutex_init(&p_lm70->lock);
 188         p_lm70->chip = chip;
 189         p_lm70->spi = spi;
 190
 191         hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev,
 192                                                            spi->modalias,
 193                                                            p_lm70, lm70_groups);
 194         return PTR_ERR_OR_ZERO(hwmon_dev);
 195 }
 196
 197 static const struct spi_device_id lm70_ids[] = {
 198         { "lm70",   LM70_CHIP_LM70 },
 199         { "tmp121", LM70_CHIP_TMP121 },
 200         { "tmp122", LM70_CHIP_TMP122 },
 201         { "lm71",   LM70_CHIP_LM71 },
 202         { "lm74",   LM70_CHIP_LM74 },
 203         { },
 204 };
 205 MODULE_DEVICE_TABLE(spi, lm70_ids);
 206
 207 static struct spi_driver lm70_driver = {
 208         .driver = {
 209                 .name   = "lm70",
 210                 .of_match_table = of_match_ptr(lm70_of_ids),
 211         },
 212         .id_table = lm70_ids,
 213         .probe  = lm70_probe,
 214 };
 215
 216 module_spi_driver(lm70_driver);
 217
 218 MODULE_AUTHOR("Kaiwan N Billimoria");
 219 MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
 220 MODULE_LICENSE("GPL");