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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * lm70.c4 *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 Bus9 * interface. The complete datasheet is available at TI's website10 * here:11 * https://www.ti.com/product/LM7012 */13 14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt15 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 39struct lm70 {40 struct spi_device *spi;41 struct mutex lock;42 unsigned int chip;43};44 45/* sysfs hook function */46static 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 use60 * 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's75 * complement value. Only the MSB 11 bits (1 sign + 10 temperature76 * 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, multiply80 * by 0.25. Also multiply by 1000 to represent in millidegrees81 * 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 is94 * followed by 9 temperature bits (D13..D5) in 2's complement95 * 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 */119out:120 mutex_unlock(&p_lm70->lock);121 return status;122}123 124static DEVICE_ATTR_RO(temp1_input);125 126static struct attribute *lm70_attrs[] = {127 &dev_attr_temp1_input.attr,128 NULL129};130 131ATTRIBUTE_GROUPS(lm70);132 133/*----------------------------------------------------------------------*/134 135#ifdef CONFIG_OF136static 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};163MODULE_DEVICE_TABLE(of, lm70_of_ids);164#endif165 166static 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 194static 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};203MODULE_DEVICE_TABLE(spi, lm70_ids);204 205static 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 214module_spi_driver(lm70_driver);215 216MODULE_AUTHOR("Kaiwan N Billimoria");217MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");218MODULE_LICENSE("GPL");219