drivers/hwmon/lm70.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * lm70.c
   4  *
   5  * The LM70 is a temperature sensor chip from National Semiconductor (NS).
   6  * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com>
   7  *
   8  * The LM70 communicates with a host processor via an SPI/Microwire Bus
   9  * interface. The complete datasheet is available at TI's website
  10  * here:
  11  * https://www.ti.com/product/LM70
  12  */
  13
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/init.h>
  17 #include <linux/module.h>
  18 #include <linux/kernel.h>
  19 #include <linux/device.h>
  20 #include <linux/err.h>
  21 #include <linux/sysfs.h>
  22 #include <linux/hwmon.h>
  23 #include <linux/mutex.h>
  24 #include <linux/mod_devicetable.h>
  25 #include <linux/of.h>
  26 #include <linux/property.h>
  27 #include <linux/spi/spi.h>
  28 #include <linux/slab.h>
  29
  30 #define DRVNAME         "lm70"
  31
  32 #define LM70_CHIP_LM70          0       /* original NS LM70 */
  33 #define LM70_CHIP_TMP121        1       /* TI TMP121/TMP123 */
  34 #define LM70_CHIP_LM71          2       /* NS LM71 */
  35 #define LM70_CHIP_LM74          3       /* NS LM74 */
  36 #define LM70_CHIP_TMP122        4       /* TI TMP122/TMP124 */
  37 #define LM70_CHIP_TMP125        5       /* TI TMP125 */
  38
  39 struct lm70 {
  40         struct spi_device *spi;
  41         struct mutex lock;
  42         unsigned int chip;
  43 };
  44
  45 /* sysfs hook function */
  46 static ssize_t temp1_input_show(struct device *dev,
  47                                 struct device_attribute *attr, char *buf)
  48 {
  49         struct lm70 *p_lm70 = dev_get_drvdata(dev);
  50         struct spi_device *spi = p_lm70->spi;
  51         int status, val = 0;
  52         u8 rxbuf[2];
  53         s16 raw = 0;
  54
  55         if (mutex_lock_interruptible(&p_lm70->lock))
  56                 return -ERESTARTSYS;
  57
  58         /*
  59          * spi_read() requires a DMA-safe buffer; so we use
  60          * spi_write_then_read(), transmitting 0 bytes.
  61          */
  62         status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
  63         if (status < 0) {
  64                 dev_warn(dev, "spi_write_then_read failed with status %d\n",
  65                          status);
  66                 goto out;
  67         }
  68         raw = (rxbuf[0] << 8) + rxbuf[1];
  69         dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
  70                 rxbuf[0], rxbuf[1], raw);
  71
  72         /*
  73          * LM70:
  74          * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
  75          * complement value. Only the MSB 11 bits (1 sign + 10 temperature
  76          * bits) are meaningful; the LSB 5 bits are to be discarded.
  77          * See the datasheet.
  78          *
  79          * Further, each bit represents 0.25 degrees Celsius; so, multiply
  80          * by 0.25. Also multiply by 1000 to represent in millidegrees
  81          * Celsius.
  82          * So it's equivalent to multiplying by 0.25 * 1000 = 250.
  83          *
  84          * LM74 and TMP121/TMP122/TMP123/TMP124:
  85          * 13 bits of 2's complement data, discard LSB 3 bits,
  86          * resolution 0.0625 degrees celsius.
  87          *
  88          * LM71:
  89          * 14 bits of 2's complement data, discard LSB 2 bits,
  90          * resolution 0.0312 degrees celsius.
  91          *
  92          * TMP125:
  93          * MSB/D15 is a leading zero. D14 is the sign-bit. This is
  94          * followed by 9 temperature bits (D13..D5) in 2's complement
  95          * data format with a resolution of 0.25 degrees celsius per unit.
  96          * LSB 5 bits (D4..D0) share the same value as D5 and get discarded.
  97          */
  98         switch (p_lm70->chip) {
  99         case LM70_CHIP_LM70:
 100                 val = ((int)raw / 32) * 250;
 101                 break;
 102
 103         case LM70_CHIP_TMP121:
 104         case LM70_CHIP_TMP122:
 105         case LM70_CHIP_LM74:
 106                 val = ((int)raw / 8) * 625 / 10;
 107                 break;
 108
 109         case LM70_CHIP_LM71:
 110                 val = ((int)raw / 4) * 3125 / 100;
 111                 break;
 112
 113         case LM70_CHIP_TMP125:
 114                 val = (sign_extend32(raw, 14) / 32) * 250;
 115                 break;
 116         }
 117
 118         status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
 119 out:
 120         mutex_unlock(&p_lm70->lock);
 121         return status;
 122 }
 123
 124 static DEVICE_ATTR_RO(temp1_input);
 125
 126 static struct attribute *lm70_attrs[] = {
 127         &dev_attr_temp1_input.attr,
 128         NULL
 129 };
 130
 131 ATTRIBUTE_GROUPS(lm70);
 132
 133 /*----------------------------------------------------------------------*/
 134
 135 #ifdef CONFIG_OF
 136 static const struct of_device_id lm70_of_ids[] = {
 137         {
 138                 .compatible = "ti,lm70",
 139                 .data = (void *) LM70_CHIP_LM70,
 140         },
 141         {
 142                 .compatible = "ti,tmp121",
 143                 .data = (void *) LM70_CHIP_TMP121,
 144         },
 145         {
 146                 .compatible = "ti,tmp122",
 147                 .data = (void *) LM70_CHIP_TMP122,
 148         },
 149         {
 150                 .compatible = "ti,tmp125",
 151                 .data = (void *) LM70_CHIP_TMP125,
 152         },
 153         {
 154                 .compatible = "ti,lm71",
 155                 .data = (void *) LM70_CHIP_LM71,
 156         },
 157         {
 158                 .compatible = "ti,lm74",
 159                 .data = (void *) LM70_CHIP_LM74,
 160         },
 161         {},
 162 };
 163 MODULE_DEVICE_TABLE(of, lm70_of_ids);
 164 #endif
 165
 166 static int lm70_probe(struct spi_device *spi)
 167 {
 168         struct device *hwmon_dev;
 169         struct lm70 *p_lm70;
 170         int chip;
 171
 172         chip = (kernel_ulong_t)spi_get_device_match_data(spi);
 173
 174         /* signaling is SPI_MODE_0 */
 175         if ((spi->mode & SPI_MODE_X_MASK) != SPI_MODE_0)
 176                 return -EINVAL;
 177
 178         /* NOTE:  we assume 8-bit words, and convert to 16 bits manually */
 179
 180         p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
 181         if (!p_lm70)
 182                 return -ENOMEM;
 183
 184         mutex_init(&p_lm70->lock);
 185         p_lm70->chip = chip;
 186         p_lm70->spi = spi;
 187
 188         hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev,
 189                                                            spi->modalias,
 190                                                            p_lm70, lm70_groups);
 191         return PTR_ERR_OR_ZERO(hwmon_dev);
 192 }
 193
 194 static const struct spi_device_id lm70_ids[] = {
 195         { "lm70",   LM70_CHIP_LM70 },
 196         { "tmp121", LM70_CHIP_TMP121 },
 197         { "tmp122", LM70_CHIP_TMP122 },
 198         { "tmp125", LM70_CHIP_TMP125 },
 199         { "lm71",   LM70_CHIP_LM71 },
 200         { "lm74",   LM70_CHIP_LM74 },
 201         { },
 202 };
 203 MODULE_DEVICE_TABLE(spi, lm70_ids);
 204
 205 static struct spi_driver lm70_driver = {
 206         .driver = {
 207                 .name   = "lm70",
 208                 .of_match_table = of_match_ptr(lm70_of_ids),
 209         },
 210         .id_table = lm70_ids,
 211         .probe  = lm70_probe,
 212 };
 213
 214 module_spi_driver(lm70_driver);
 215
 216 MODULE_AUTHOR("Kaiwan N Billimoria");
 217 MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
 218 MODULE_LICENSE("GPL");