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 National's website
  10  * here:
  11  * http://www.national.com/pf/LM/LM70.html
  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/spi/spi.h>
  26 #include <linux/slab.h>
  27 #include <linux/of_device.h>
  28
  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
  38 struct lm70 {
  39         struct spi_device *spi;
  40         struct mutex lock;
  41         unsigned int chip;
  42 };
  43
  44 /* sysfs hook function */
  45 static ssize_t temp1_input_show(struct device *dev,
  46                                 struct device_attribute *attr, char *buf)
  47 {
  48         struct lm70 *p_lm70 = dev_get_drvdata(dev);
  49         struct spi_device *spi = p_lm70->spi;
  50         int status, val = 0;
  51         u8 rxbuf[2];
  52         s16 raw = 0;
  53
  54         if (mutex_lock_interruptible(&p_lm70->lock))
  55                 return -ERESTARTSYS;
  56
  57         /*
  58          * spi_read() requires a DMA-safe buffer; so we use
  59          * spi_write_then_read(), transmitting 0 bytes.
  60          */
  61         status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
  62         if (status < 0) {
  63                 dev_warn(dev, "spi_write_then_read failed with status %d\n",
  64                          status);
  65                 goto out;
  66         }
  67         raw = (rxbuf[0] << 8) + rxbuf[1];
  68         dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
  69                 rxbuf[0], rxbuf[1], raw);
  70
  71         /*
  72          * LM70:
  73          * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
  74          * complement value. Only the MSB 11 bits (1 sign + 10 temperature
  75          * bits) are meaningful; the LSB 5 bits are to be discarded.
  76          * See the datasheet.
  77          *
  78          * Further, each bit represents 0.25 degrees Celsius; so, multiply
  79          * by 0.25. Also multiply by 1000 to represent in millidegrees
  80          * Celsius.
  81          * So it's equivalent to multiplying by 0.25 * 1000 = 250.
  82          *
  83          * LM74 and TMP121/TMP122/TMP123/TMP124:
  84          * 13 bits of 2's complement data, discard LSB 3 bits,
  85          * resolution 0.0625 degrees celsius.
  86          *
  87          * LM71:
  88          * 14 bits of 2's complement data, discard LSB 2 bits,
  89          * resolution 0.0312 degrees celsius.
  90          */
  91         switch (p_lm70->chip) {
  92         case LM70_CHIP_LM70:
  93                 val = ((int)raw / 32) * 250;
  94                 break;
  95
  96         case LM70_CHIP_TMP121:
  97         case LM70_CHIP_TMP122:
  98         case LM70_CHIP_LM74:
  99                 val = ((int)raw / 8) * 625 / 10;
 100                 break;
 101
 102         case LM70_CHIP_LM71:
 103                 val = ((int)raw / 4) * 3125 / 100;
 104                 break;
 105         }
 106
 107         status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
 108 out:
 109         mutex_unlock(&p_lm70->lock);
 110         return status;
 111 }
 112
 113 static DEVICE_ATTR_RO(temp1_input);
 114
 115 static struct attribute *lm70_attrs[] = {
 116         &dev_attr_temp1_input.attr,
 117         NULL
 118 };
 119
 120 ATTRIBUTE_GROUPS(lm70);
 121
 122 /*----------------------------------------------------------------------*/
 123
 124 #ifdef CONFIG_OF
 125 static const struct of_device_id lm70_of_ids[] = {
 126         {
 127                 .compatible = "ti,lm70",
 128                 .data = (void *) LM70_CHIP_LM70,
 129         },
 130         {
 131                 .compatible = "ti,tmp121",
 132                 .data = (void *) LM70_CHIP_TMP121,
 133         },
 134         {
 135                 .compatible = "ti,tmp122",
 136                 .data = (void *) LM70_CHIP_TMP122,
 137         },
 138         {
 139                 .compatible = "ti,lm71",
 140                 .data = (void *) LM70_CHIP_LM71,
 141         },
 142         {
 143                 .compatible = "ti,lm74",
 144                 .data = (void *) LM70_CHIP_LM74,
 145         },
 146         {},
 147 };
 148 MODULE_DEVICE_TABLE(of, lm70_of_ids);
 149 #endif
 150
 151 static int lm70_probe(struct spi_device *spi)
 152 {
 153         const struct of_device_id *match;
 154         struct device *hwmon_dev;
 155         struct lm70 *p_lm70;
 156         int chip;
 157
 158         match = of_match_device(lm70_of_ids, &spi->dev);
 159         if (match)
 160                 chip = (int)(uintptr_t)match->data;
 161         else
 162                 chip = spi_get_device_id(spi)->driver_data;
 163
 164         /* signaling is SPI_MODE_0 */
 165         if (spi->mode & (SPI_CPOL | SPI_CPHA))
 166                 return -EINVAL;
 167
 168         /* NOTE:  we assume 8-bit words, and convert to 16 bits manually */
 169
 170         p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
 171         if (!p_lm70)
 172                 return -ENOMEM;
 173
 174         mutex_init(&p_lm70->lock);
 175         p_lm70->chip = chip;
 176         p_lm70->spi = spi;
 177
 178         hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev,
 179                                                            spi->modalias,
 180                                                            p_lm70, lm70_groups);
 181         return PTR_ERR_OR_ZERO(hwmon_dev);
 182 }
 183
 184 static const struct spi_device_id lm70_ids[] = {
 185         { "lm70",   LM70_CHIP_LM70 },
 186         { "tmp121", LM70_CHIP_TMP121 },
 187         { "tmp122", LM70_CHIP_TMP122 },
 188         { "lm71",   LM70_CHIP_LM71 },
 189         { "lm74",   LM70_CHIP_LM74 },
 190         { },
 191 };
 192 MODULE_DEVICE_TABLE(spi, lm70_ids);
 193
 194 static struct spi_driver lm70_driver = {
 195         .driver = {
 196                 .name   = "lm70",
 197                 .of_match_table = of_match_ptr(lm70_of_ids),
 198         },
 199         .id_table = lm70_ids,
 200         .probe  = lm70_probe,
 201 };
 202
 203 module_spi_driver(lm70_driver);
 204
 205 MODULE_AUTHOR("Kaiwan N Billimoria");
 206 MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
 207 MODULE_LICENSE("GPL");