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 50 struct lm70 { 51 struct spi_device *spi; 52 struct mutex lock; 53 unsigned int chip; 54 }; 55 56 /* sysfs hook function */ 57 static ssize_t lm70_sense_temp(struct device *dev, 58 struct device_attribute *attr, char *buf) 59 { 60 struct lm70 *p_lm70 = dev_get_drvdata(dev); 61 struct spi_device *spi = p_lm70->spi; 62 int status, val = 0; 63 u8 rxbuf[2]; 64 s16 raw = 0; 65 66 if (mutex_lock_interruptible(&p_lm70->lock)) 67 return -ERESTARTSYS; 68 69 /* 70 * spi_read() requires a DMA-safe buffer; so we use 71 * spi_write_then_read(), transmitting 0 bytes. 72 */ 73 status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2); 74 if (status < 0) { 75 pr_warn("spi_write_then_read failed with status %d\n", status); 76 goto out; 77 } 78 raw = (rxbuf[0] << 8) + rxbuf[1]; 79 dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n", 80 rxbuf[0], rxbuf[1], raw); 81 82 /* 83 * LM70: 84 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's 85 * complement value. Only the MSB 11 bits (1 sign + 10 temperature 86 * bits) are meaningful; the LSB 5 bits are to be discarded. 87 * See the datasheet. 88 * 89 * Further, each bit represents 0.25 degrees Celsius; so, multiply 90 * by 0.25. Also multiply by 1000 to represent in millidegrees 91 * Celsius. 92 * So it's equivalent to multiplying by 0.25 * 1000 = 250. 93 * 94 * LM74 and TMP121/TMP123: 95 * 13 bits of 2's complement data, discard LSB 3 bits, 96 * resolution 0.0625 degrees celsius. 97 * 98 * LM71: 99 * 14 bits of 2's complement data, discard LSB 2 bits, 100 * resolution 0.0312 degrees celsius. 101 */ 102 switch (p_lm70->chip) { 103 case LM70_CHIP_LM70: 104 val = ((int)raw / 32) * 250; 105 break; 106 107 case LM70_CHIP_TMP121: 108 case LM70_CHIP_LM74: 109 val = ((int)raw / 8) * 625 / 10; 110 break; 111 112 case LM70_CHIP_LM71: 113 val = ((int)raw / 4) * 3125 / 100; 114 break; 115 } 116 117 status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */ 118 out: 119 mutex_unlock(&p_lm70->lock); 120 return status; 121 } 122 123 static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL); 124 125 static struct attribute *lm70_attrs[] = { 126 &dev_attr_temp1_input.attr, 127 NULL 128 }; 129 130 ATTRIBUTE_GROUPS(lm70); 131 132 /*----------------------------------------------------------------------*/ 133 134 #ifdef CONFIG_OF 135 static const struct of_device_id lm70_of_ids[] = { 136 { 137 .compatible = "ti,lm70", 138 .data = (void *) LM70_CHIP_LM70, 139 }, 140 { 141 .compatible = "ti,tmp121", 142 .data = (void *) LM70_CHIP_TMP121, 143 }, 144 { 145 .compatible = "ti,lm71", 146 .data = (void *) LM70_CHIP_LM71, 147 }, 148 { 149 .compatible = "ti,lm74", 150 .data = (void *) LM70_CHIP_LM74, 151 }, 152 {}, 153 }; 154 MODULE_DEVICE_TABLE(of, lm70_of_ids); 155 #endif 156 157 static int lm70_probe(struct spi_device *spi) 158 { 159 const struct of_device_id *match; 160 struct device *hwmon_dev; 161 struct lm70 *p_lm70; 162 int chip; 163 164 match = of_match_device(lm70_of_ids, &spi->dev); 165 if (match) 166 chip = (int)(uintptr_t)match->data; 167 else 168 chip = spi_get_device_id(spi)->driver_data; 169 170 /* signaling is SPI_MODE_0 */ 171 if (spi->mode & (SPI_CPOL | SPI_CPHA)) 172 return -EINVAL; 173 174 /* NOTE: we assume 8-bit words, and convert to 16 bits manually */ 175 176 p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL); 177 if (!p_lm70) 178 return -ENOMEM; 179 180 mutex_init(&p_lm70->lock); 181 p_lm70->chip = chip; 182 p_lm70->spi = spi; 183 184 hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev, 185 spi->modalias, 186 p_lm70, lm70_groups); 187 return PTR_ERR_OR_ZERO(hwmon_dev); 188 } 189 190 static const struct spi_device_id lm70_ids[] = { 191 { "lm70", LM70_CHIP_LM70 }, 192 { "tmp121", LM70_CHIP_TMP121 }, 193 { "lm71", LM70_CHIP_LM71 }, 194 { "lm74", LM70_CHIP_LM74 }, 195 { }, 196 }; 197 MODULE_DEVICE_TABLE(spi, lm70_ids); 198 199 static struct spi_driver lm70_driver = { 200 .driver = { 201 .name = "lm70", 202 .of_match_table = of_match_ptr(lm70_of_ids), 203 }, 204 .id_table = lm70_ids, 205 .probe = lm70_probe, 206 }; 207 208 module_spi_driver(lm70_driver); 209 210 MODULE_AUTHOR("Kaiwan N Billimoria"); 211 MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver"); 212 MODULE_LICENSE("GPL"); 213