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 #include <linux/init.h> 28 #include <linux/module.h> 29 #include <linux/kernel.h> 30 #include <linux/device.h> 31 #include <linux/err.h> 32 #include <linux/sysfs.h> 33 #include <linux/hwmon.h> 34 #include <linux/mutex.h> 35 #include <linux/mod_devicetable.h> 36 #include <linux/spi/spi.h> 37 38 39 #define DRVNAME "lm70" 40 41 #define LM70_CHIP_LM70 0 /* original NS LM70 */ 42 #define LM70_CHIP_TMP121 1 /* TI TMP121/TMP123 */ 43 44 struct lm70 { 45 struct device *hwmon_dev; 46 struct mutex lock; 47 unsigned int chip; 48 }; 49 50 /* sysfs hook function */ 51 static ssize_t lm70_sense_temp(struct device *dev, 52 struct device_attribute *attr, char *buf) 53 { 54 struct spi_device *spi = to_spi_device(dev); 55 int status, val = 0; 56 u8 rxbuf[2]; 57 s16 raw=0; 58 struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev); 59 60 if (mutex_lock_interruptible(&p_lm70->lock)) 61 return -ERESTARTSYS; 62 63 /* 64 * spi_read() requires a DMA-safe buffer; so we use 65 * spi_write_then_read(), transmitting 0 bytes. 66 */ 67 status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2); 68 if (status < 0) { 69 printk(KERN_WARNING 70 "spi_write_then_read failed with status %d\n", status); 71 goto out; 72 } 73 raw = (rxbuf[0] << 8) + rxbuf[1]; 74 dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n", 75 rxbuf[0], rxbuf[1], raw); 76 77 /* 78 * LM70: 79 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's 80 * complement value. Only the MSB 11 bits (1 sign + 10 temperature 81 * bits) are meaningful; the LSB 5 bits are to be discarded. 82 * See the datasheet. 83 * 84 * Further, each bit represents 0.25 degrees Celsius; so, multiply 85 * by 0.25. Also multiply by 1000 to represent in millidegrees 86 * Celsius. 87 * So it's equivalent to multiplying by 0.25 * 1000 = 250. 88 * 89 * TMP121/TMP123: 90 * 13 bits of 2's complement data, discard LSB 3 bits, 91 * resolution 0.0625 degrees celsius. 92 */ 93 switch (p_lm70->chip) { 94 case LM70_CHIP_LM70: 95 val = ((int)raw / 32) * 250; 96 break; 97 98 case LM70_CHIP_TMP121: 99 val = ((int)raw / 8) * 625 / 10; 100 break; 101 } 102 103 status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */ 104 out: 105 mutex_unlock(&p_lm70->lock); 106 return status; 107 } 108 109 static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL); 110 111 static ssize_t lm70_show_name(struct device *dev, struct device_attribute 112 *devattr, char *buf) 113 { 114 struct lm70 *p_lm70 = dev_get_drvdata(dev); 115 int ret; 116 117 switch (p_lm70->chip) { 118 case LM70_CHIP_LM70: 119 ret = sprintf(buf, "lm70\n"); 120 break; 121 case LM70_CHIP_TMP121: 122 ret = sprintf(buf, "tmp121\n"); 123 break; 124 default: 125 ret = -EINVAL; 126 } 127 return ret; 128 } 129 130 static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL); 131 132 /*----------------------------------------------------------------------*/ 133 134 static int __devinit lm70_probe(struct spi_device *spi) 135 { 136 int chip = spi_get_device_id(spi)->driver_data; 137 struct lm70 *p_lm70; 138 int status; 139 140 /* signaling is SPI_MODE_0 for both LM70 and TMP121 */ 141 if (spi->mode & (SPI_CPOL | SPI_CPHA)) 142 return -EINVAL; 143 144 /* 3-wire link (shared SI/SO) for LM70 */ 145 if (chip == LM70_CHIP_LM70 && !(spi->mode & SPI_3WIRE)) 146 return -EINVAL; 147 148 /* NOTE: we assume 8-bit words, and convert to 16 bits manually */ 149 150 p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL); 151 if (!p_lm70) 152 return -ENOMEM; 153 154 mutex_init(&p_lm70->lock); 155 p_lm70->chip = chip; 156 157 /* sysfs hook */ 158 p_lm70->hwmon_dev = hwmon_device_register(&spi->dev); 159 if (IS_ERR(p_lm70->hwmon_dev)) { 160 dev_dbg(&spi->dev, "hwmon_device_register failed.\n"); 161 status = PTR_ERR(p_lm70->hwmon_dev); 162 goto out_dev_reg_failed; 163 } 164 dev_set_drvdata(&spi->dev, p_lm70); 165 166 if ((status = device_create_file(&spi->dev, &dev_attr_temp1_input)) 167 || (status = device_create_file(&spi->dev, &dev_attr_name))) { 168 dev_dbg(&spi->dev, "device_create_file failure.\n"); 169 goto out_dev_create_file_failed; 170 } 171 172 return 0; 173 174 out_dev_create_file_failed: 175 device_remove_file(&spi->dev, &dev_attr_temp1_input); 176 hwmon_device_unregister(p_lm70->hwmon_dev); 177 out_dev_reg_failed: 178 dev_set_drvdata(&spi->dev, NULL); 179 kfree(p_lm70); 180 return status; 181 } 182 183 static int __devexit lm70_remove(struct spi_device *spi) 184 { 185 struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev); 186 187 device_remove_file(&spi->dev, &dev_attr_temp1_input); 188 device_remove_file(&spi->dev, &dev_attr_name); 189 hwmon_device_unregister(p_lm70->hwmon_dev); 190 dev_set_drvdata(&spi->dev, NULL); 191 kfree(p_lm70); 192 193 return 0; 194 } 195 196 197 static const struct spi_device_id lm70_ids[] = { 198 { "lm70", LM70_CHIP_LM70 }, 199 { "tmp121", LM70_CHIP_TMP121 }, 200 { }, 201 }; 202 MODULE_DEVICE_TABLE(spi, lm70_ids); 203 204 static struct spi_driver lm70_driver = { 205 .driver = { 206 .name = "lm70", 207 .owner = THIS_MODULE, 208 }, 209 .id_table = lm70_ids, 210 .probe = lm70_probe, 211 .remove = __devexit_p(lm70_remove), 212 }; 213 214 static int __init init_lm70(void) 215 { 216 return spi_register_driver(&lm70_driver); 217 } 218 219 static void __exit cleanup_lm70(void) 220 { 221 spi_unregister_driver(&lm70_driver); 222 } 223 224 module_init(init_lm70); 225 module_exit(cleanup_lm70); 226 227 MODULE_AUTHOR("Kaiwan N Billimoria"); 228 MODULE_DESCRIPTION("NS LM70 / TI TMP121/TMP123 Linux driver"); 229 MODULE_LICENSE("GPL"); 230